Boscia aqueous extract. senegalensis on hyperglycemia, hyperlipidemia and oxidative stress induced in rats. The aqueous extract was prepared from B. senegalensis seed powders under the extraction conditions: time (10 ...Boscia aqueous extract. senegalensis on hyperglycemia, hyperlipidemia and oxidative stress induced in rats. The aqueous extract was prepared from B. senegalensis seed powders under the extraction conditions: time (10 min), temperature (55˚C) and the ratio of mass of flour/volume of water (3/10 g/mL). Male wistar rats aged 6 to 8 weeks were acclimated and divided into 8 groups of 5 rats each: two normal control groups which received a normal standard diet (3810 kcal/kg), and six test groups which were subjected to a hyperlipidemic diet (5310 Kcal/kg). All groups of animals were fed in this manner for 8 weeks to induce hyperglycemia, hyperlipidemia and oxidative stress. After induction the animals were treated either with distilled water for the normal and negative control groups or with atorvastatin for the positive control group or with the extract of B. senegalensis. (125, 250 and 500 mg/kg) for the test groups. Fasting blood glucose was taken every 7 days during induction. After sacrifice, biochemical and oxidative stress parameters were measured. The aqueous extract of B. senegalensis significantly decreased (p B. senegalensis at a dose of 500 mg/kg has the capacity to reduce blood sugar, improve the quality of the lipid profile and reduce oxidative stress. Thus, the results reveal that the aqueous extract of B. senegalensis has powerful hypoglycemic, hypolipidemic and antioxidant properties.展开更多
Cardiovascular diseases are serious pathologies that affect an increasing number of people. Several preventive measures are generally used, including supplementing of oils in foods. Our objective was to compare the ef...Cardiovascular diseases are serious pathologies that affect an increasing number of people. Several preventive measures are generally used, including supplementing of oils in foods. Our objective was to compare the effects of Tetracarpidum conophorum oil (TC) and corn oil (CO) on serum lipid profiles of normal male rats. 42 Wistar rats were divided into 7 groups. Diets included TC oil (groups TC5, TC10 and TC20) and corn oil (groups CO5, CO10 and CO20) in proportions of 5%, 10% and 20%, with a control group (T). After 5 weeks of feeding, several parameters were measured during and after the study, including body weight, food intake and organ weights (kidney, liver and fat). Lipid profiles (total cholesterol, TG, HDL and LDL), glucose and protein levels were measured in the serum. The increase in body mass was inversely proportional to the amount of oil in the food. The decrease in body mass and adiposomatic index of group TC10 was significant (p < 0.05) compared with the other groups. The lowest glycaemia (64.17 ± 5.14 mg/dl) was noted with the diet containing 20% TC oil. A significant reduction in total cholesterol, LDL fraction and blood triglycerides was observed in the groups supplemented with TC and corn oils compared to controls. Results were also more beneficial for the TC10 group. HDL-cholesterol levels were significantly higher (p < 0.05) in the oil-supplemented groups than in the control group. Castelli’s risk indices decrease significantly (p < 0.05) with increasing oil content for TC. The oils had no impact on blood protein contents. One can conclude that a diet containing 10% crude oil from TC kernels could prevent or alleviate cardiovascular diseases and glycemia.展开更多
The production and consumption of avocado pears generates tons of wastes, mainly the pear peels which are usually discarded, although they have been reported to contain important phyto-chemicals with biological activi...The production and consumption of avocado pears generates tons of wastes, mainly the pear peels which are usually discarded, although they have been reported to contain important phyto-chemicals with biological activities. The adverse health effect associated with the consumption of saturated lipid based foods has ignited research on reformulation of lipid based foods to eliminate Trans Fatty Acids (TFAs). This study was thus aimed at the extraction and characterization of oil from Avocado Peels (APO) and evaluation of the quality of margarine produced from it. Five verities of pear were used for oil extraction by soxhlet method and physiochemical, oxidative, functional and antioxidant characterization was done. Margarines were formulated using a central composite design using oil blends of APO and Virgin Coconut Oil (VCO) with an oil ratio of 10:90, 40:60, 70:30 respectively, varied blending speed, blending time, and chitosan concentration. Samples were characterized and the effect of process parameters on the physiochemical and functional properties of the margarine studied. Optimized conditions were used to produce samples for sensory evaluation. Color, spreadability, aroma, taste and general acceptability was evaluated using ranking difference test. The results showed that the yield, density, and iodine values of APOs oils ranged from 14.91 ± 0.18 to 11.76 ± 0.46;0.93 ± 0.001 to 0.99 ± 0.1;46.63 ± 1.70 to 52.4 ± 0.63, their acid values, TBA and PV values ranged from 1.42 ± 0.39 to 1.97 ± 0.5;0.11 ± 0.002 to 0.18 ± 0.04;and 2.72 ± 0.14 to 4.43 ± 0.36 respectively, with Brogdon avocado peel variety having the overall best properties prepared blends of trans-free APO margarines showed that increase in APO ratio decreased melting point, increased oxidative stability and reduced moisture content of margarine samples. Chitosan addition leads to decrease moisture content and increase functional properties. VCO lead to increase in phenolic and flavonoid content of the margarines. Samples were spreadable and palatable with R20 being most palatable and the most accepted being R26 with a mean score of 7.07 ± 0.70. Decrease in color intensity increased acceptability. This study therefore demonstrated that avocado peel waste biomass can be valorized by using it as raw material for oil extraction, which can serve as good material for the production of trans-free margarines with good oxidative stability, functional and antioxidant properties.展开更多
The objective of this work is to improve the physical and mechanical properties of stabilized earth blocks (BTC) used in construction in the Ndé department of Cameroon. To achieve this, two stabilizers, cement an...The objective of this work is to improve the physical and mechanical properties of stabilized earth blocks (BTC) used in construction in the Ndé department of Cameroon. To achieve this, two stabilizers, cement and sawdust, were used at varying percentages of 0%, 4%, 6%, and 8%. Physical characterization tests, including natural water content, specific weight, jar test, Protor, and Atterberg limits, were conducted. Additionally, mechanical tests, such as compression and three-point bending, were performed. The results show that as the amount of stabilizer increases, the density of BTC decreases. The samples with 8% sawdust have the highest density, while those without stabilizers have the lowest. Porosity decreases as sawdust and cement content increases, with smaller values observed in samples with 8% sawdust or cement. Our tests indicate that blocks stabilized with cement have slightly higher compressive strength than those stabilized with sawdust. However, the water absorption rate increases with higher sawdust content.展开更多
Information about the type of gene action governing the inheritance of cowpea seed flavonoid content and antioxidant activity is prerequisite for starting an effective breeding program for developing improved varietie...Information about the type of gene action governing the inheritance of cowpea seed flavonoid content and antioxidant activity is prerequisite for starting an effective breeding program for developing improved varieties. For this purpose, half-diallel crosses among seven diverse parents were made. The homozygous parents and 21 F1 hybrids were evaluated at Maroua in the Sudano-Sahelian zone of Cameroon using a randomized complete block design with three replicates. Flour samples produced from decorticated seeds were used for biochemical analysis. Analysis of variance showed significant differences(P < 0.001) among genotypes for the studied traits with ranges of 363.6–453.9 mg rutin equivalent per 100 g dry weight(DW) for total flavonoids, 13.38–30.73 mg ascorbic acid equivalent per 1 g DW for ferric iron reducing activity, 70.98–266.93 mg trolox equivalent per 100 g DW for 2,2-diphenyl-1-picrylhydrazyl(DPPH) free radical scavenging activity, and 90.93–370.62 mg trolox equivalent per 100 g DW for 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS) free radical scavenging activity. Both additive and non-additive gene effects were significant in the genetic control of these traits, but dominance variance was greater than additive variance. The traits were mainly controlled by overdominance model suggesting a selection in the delayed generations.Broad- and narrow-sense heritability estimates varied from 0.90 to 0.99 and from 0.12 to 0.45,respectively. The variances due to both general and specific combining ability were highly significant for all studied traits. Recessive alleles had positive effects on DPPH and ABTS scavenging activities, whereas dominant alleles had positive effects on flavonoid content and ferric iron reducing activity. These results could help cowpea breeders to improve the antioxidant potential of cowpea seeds by appropriate selection.展开更多
Maintenance of glycemic control is important in preventing diabetes and its associated complications. Considering the current recommended approach for the use of functional foods and their bioactive components in the ...Maintenance of glycemic control is important in preventing diabetes and its associated complications. Considering the current recommended approach for the use of functional foods and their bioactive components in the prevention and management of diabetes, the aim of this study was to determine the antihyperglycemic effect of Moringa oleifera functional tea in rat models and in normoglycemic human volunteers using the oral glucose tolerance test (OGTT). Moringa tea prepared by extracting Moringa leaf powder in distilled water (1:20 mg/ml) at 97°C for 30 min was administered at different doses to male Wistar rats and human volunteers prior to glucose loading. Blood glucose was measured at intervals of 30 min for 150 min. Consumption of Moringa tea prior to glucose loading suppressed the elevation in blood glucose in all cases compared to controls that did not receive the tea initially. The degree and pattern of decrease however, were dose dependent. In rats, intermediate doses of 20 ml/kg BW were more effective in reducing blood glucose overall (18.2%) vs 13.3% and 6% at doses of 10 and 30 ml/kg BW respectively. In humans, the final decrease in blood glucose was not significantly different for high 400 ml (19%) and low 200 ml (17%) doses. Of interest here was the pattern of decrease, being significantly higher (p < 0.05) at 30 min with 200 ml (22.8%) than with 400 ml (17.9%). It is suggested that low doses exert their antihyperglycemic effect more at intestinal level by inhibiting glucose absorption, whereas high doses exert their effect more in circulation. We conclude that Moringa oleifera tea has potential as a functional food in the management of hyperglycemia.展开更多
The project consists in the implementation of a biocomposite based on tannin resin and natural rubber matrices with the bast fibres of <i>Triumfetta cordifolia </i>A.Rich.“<i>Okong</i>” from ...The project consists in the implementation of a biocomposite based on tannin resin and natural rubber matrices with the bast fibres of <i>Triumfetta cordifolia </i>A.Rich.“<i>Okong</i>” from the equatorial region of Cameroon as reinforcement. A study of this still little known fibre is necessary. This paper evaluates the physico-chemical and mechanical characteristics of the fibers. The fibers are extracted by us. A series of experiments is conducted for this purpose: morphological observation with a scanning electron microscope (SEM);density evaluation with a helium pycnometer;absorption rate evaluation according to the protocol available in the literature, Fourier Transform Infrared Spectrometry (FT-IR), chemical composition evaluation according to ASTM 1972 and ASTM 1977 standards, thermogravimetric analysis (TGA) and tensile tests on fiber bundles according to NF T25-501-3. The results show that the fiber is made up of several elementary fibers with oval cross-sections. A density of 1.477g/cm<sup>3</sup> close to that of hemp. These fibers have a water absorption rate of 342.5%, which correlates with the presence of free hydroxyl functional groups obtained from the spectrometry study (FT-IR). Chemical analysis reveals that the fiber is made up of celluloses (44.4%), hemicelluloses (30.8%), lignins (18.9%), pectins (3.3%), waxes (0.5%) and minerals (2.1%). In addition, we learn that the fibers studied dehydrate at 11.49%, showinga notable thermal stability around 235°C with a peak thermal decomposition of cellulose located at 420°C. In terms of mechanical behaviour, the results reveal that the fibers offer a Young’s modulus in traction of 12.4 ± 6.9 GPa, a tensile strength of 526 ± 128 MPa and an elongation at break of 2.25%. The information thus obtained makes it possible to place these fibers in the same fiber group as flax and jute. They could therefore be used for the same types of applications. They also inform us that these fibers can withstand the temperatures of composite shaping by thermocompression.展开更多
The content of soluble sugar in cowpea(Vigna unguiculata L. Walp.) seeds is important for their acceptability to consumers. The objective of this study was to evaluate the genetic control of soluble sugar content in c...The content of soluble sugar in cowpea(Vigna unguiculata L. Walp.) seeds is important for their acceptability to consumers. The objective of this study was to evaluate the genetic control of soluble sugar content in cowpea using diallel analysis. For this purpose,half-diallel crosses were made among seven diverse parents. The amount of total soluble sugar was estimated by the phenol sulfuric acid reagent method and reducing sugar were measured by the DNS(3,5-dinitrosalicylic acid) reagent method. The total soluble sugar ranged from 11.12(VYA) to 40.79 mg g^(-1)(IT93 K-693-2) with a mean of 22.31 mg g^(-1).Reducing soluble sugar showed a mean value of 9.11 mg g^(-1) and ranged from 13.61(TVx3236) to 4.98 mg g^(-1)(Lori niebe). Diallel analysis showed that both additive and non-additive gene effects were significant in the genetic control of these traits. However,dominance variance was greater than additive variance for soluble sugar. The traits were controlled mainly by an overdominance model, suggesting the advantage of delaying selection to later generations. Soluble sugar content was found to be highly heritable, with broad-sense heritability ranging from 0.987 to 0.976. Narrow-sense heritability ranged from0.154 to 0.422 and revealed the lower importance of additive variance. Parents and F_1 hybrids differed significantly on the basis of their general and specific combining abilities,respectively. Recessive alleles had positive effects on total soluble sugar and reducing soluble sugar. These results could help cowpea breeders improve the acceptability of cowpea seeds and cowpea-based foods by appropriate selection.展开更多
Dried leaves of <i><span style="font-family:Verdana;">Eucalyptus</span></i> <i><span style="font-family:Verdana;">camaldulensis</span></i><span st...Dried leaves of <i><span style="font-family:Verdana;">Eucalyptus</span></i> <i><span style="font-family:Verdana;">camaldulensis</span></i><span style="font-family:Verdana;"> were finely grinded and fractionated</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> by sieving into four granulometric classes (<100 μm, 100 - 200 μm, 200 - 355 μm and >355 μm). The obtained powder fractions were used for essential oil (EO) extraction by hydrodistillation and their phytochemical profile and </span><i><span style="font-family:Verdana;">in</span></i> <i><span style="font-family:Verdana;">vitro</span></i><span style="font-family:Verdana;"> antioxidant activities were evaluated. The mother powder (unsieved powder) was used for comparison. Particle size exerted a significant influence (</span><i><span style="font-family:Verdana;">p</span></i><span style="font-family:Verdana;"> < 0.05) on the phytochemical composition and </span><i><span style="font-family:Verdana;">in</span></i> <i><span style="font-family:Verdana;">vitro</span></i><span style="font-family:Verdana;"> antioxidant prop</span><span><span style="font-family:Verdana;">erties of the EOs. Comparatively, the mother powder had the highest contents of </span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;">-pinene (55.6%), camphene (3.4%) and limonene (3.7%), while 1,8-cineole (26.6% and 22.4%), </span></span><span style="font-family:Verdana;">exo-fenchol (5.6% and 3.5%), </span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;">-campholenol (4.2% and 3.4%), L-trans-pinocarveol (5.5% and 2.7%), L-borneol (12.6% and 6.8%) and </span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;">-terpineol (16.4% and 7.6%) are the main compounds of EOs from the <100 μm and 100 - 200 μm fractions, respectively. The antioxidant activities of the EOs revealed higher radical-scavenging activities DPPH (90.62% and 70.46%) and ABTS (89.59% and 73.31%) for finer fractions (<100 μm and 100 - 200 μm, respectively). The best reducing power (36.15% and 34.27%) were also found in these finer powder fractions which improved by more than 2 times the value of mother powder (reducing power of 17.01%). These results suggest that grinding followed by sieve fractionation concentrates the majority of antioxidant phytochemicals in the EOs of the finer powder fractions of </span><i><span style="font-family:Verdana;">E.</span></i> <i><span style="font-family:Verdana;">camaldulensis</span></i><span style="font-family:Verdana;"> leaves. Finer powders could be used as functional ingredients in food formulations for the management of chronic diseases.</span></span>展开更多
Computer grids are infrastructures in which heterogeneous and distributed resources offer very high computing or storage performance. If they offer extreme computing performance, they are also subject to the appearanc...Computer grids are infrastructures in which heterogeneous and distributed resources offer very high computing or storage performance. If they offer extreme computing performance, they are also subject to the appearance of many failures related to this type of architecture. While performing tasks, if the response time of a node in the system incomprehensibly exceeds the requirements of the specifications, the node experiences an omission failure. The task running in the failed node will be unavailable until the node resumes normal activity. Waiting not being a possible solution, many fault tolerance methods have been proposed. Despite this large number of fault tolerance methods on offer, computer grids are still prone to many failures by omission. In this work, a numerical study of the failures by omission which occur in the calculation grids during the execution of the tasks was carried out and a model allowing anticipating its failures was proposed with the formalism PDEVS (Parallel Discret EVent system Specification).展开更多
In African communities, traditional beer drinking remains a unifying factor within its populations both socially, commercially, culturally, politically, in health and nutrition and for some ritual practices. In this r...In African communities, traditional beer drinking remains a unifying factor within its populations both socially, commercially, culturally, politically, in health and nutrition and for some ritual practices. In this research a field survey was carried out to investigate the consumption of corn beer and in particular <i>Nkang</i> in the North-West Region of Cameroon. The tools that were employed to carry out these investigations included face-to-face interviews and the use of properly designed questionnaires. Results from the survey showed that three types of maize-based beverages are drunk in the North-West Region of Cameroon, which are locally called <i>Kwacha</i> (whitish, most viscous and most turbid), <i>Sha-ah</i> (cream white, viscous and turbid) and <i>Nkang</i> (dark brown, least viscous and least turbid) in terms of colour, viscosity and turbidity. The percentage awareness of the existence of these beers from the sampled population gave the following values;60.9% for <i>Kwacha</i>, 100% for <i>Sha-ah</i> and 89.1% for <i>Nkang</i>. Nonetheless, 54.5% of the 60.9% of those who were aware of the existence of <i>kwacha</i> had at least tasted it. Also 98.2% out of the 100% for <i>Sha-ah</i> and 85.5% out of 89.1% for <i>Nkang</i> had tasted them, too. <i>Nkang</i> was found to be the most preferred to <i>Sha-ah</i> then <i>Kwacha</i> in that order by the consumers since <i>Nkang</i> is very tasteful, least alcoholic, least turbid, least viscous, has the most attractive colour than the others, has a significant impact on the culture of some localities in this region and as well as it is natural and nutritious. However, <i>Nkang</i> as well as the other two has varying organoleptic properties, unsatisfactory conservation and short shelf-life. Hence are consumed within a short period of time from their production. Because of the low alcoholic content of <i>Nkang</i>, the beverage is consumed by both adults (most elderly), children, those who have health problems and it is mostly preferred by some Christians though not frequently seen in the markets. It was equally observed that the little quantity of <i>Nkang</i> found in the markets is of poor quality which keeps dropping everyday thus an indication of its risk becoming extinct. Therefore, if <i>Nkang</i> is clarified and its quality improved, the problems can be solved as even attested by the consumers who say they will buy at even a higher price if clarify. As well as those who want it for their cultural reasons do not want it to face out too.展开更多
This paper presents the optimization of the PV/battery system including extrapolation of the electrical demand. Matlab software was chosen to implement the algorithm. PVC, the number of PV modules and battery capacity...This paper presents the optimization of the PV/battery system including extrapolation of the electrical demand. Matlab software was chosen to implement the algorithm. PVC, the number of PV modules and battery capacity increase with increasing electrical demand. This makes it possible to predict the device according to the electrical demand. Particle swarm optimization is used to minimize the total cost of the system over 20</span><span style="font-size:10.0pt;font-family:""> </span><span style="font-size:10.0pt;font-family:"">year</span><span style="font-size:10.0pt;font-family:"">s</span><span style="font-size:10.0pt;font-family:"">. The average cost of energy is $0.369/kWh.展开更多
In this paper, we present a new robust hybrid algorithm combining successively chaotic encryption and blind watermarking of images based on the quaternionic wavelet transform (QWT) to ensure the secure transfer of dig...In this paper, we present a new robust hybrid algorithm combining successively chaotic encryption and blind watermarking of images based on the quaternionic wavelet transform (QWT) to ensure the secure transfer of digital data. The calculations of the different evaluation parameters have been performed in order to determine the robustness of our algorithm to certain attacks. The application of this hybrid algorithm on CFA (Color Filter Array) images, allowed us to guarantee the integrity of the digital data and to propose an autonomous transmission system. The results obtained after simulation of this successive hybrid algorithm of chaotic encryption and then blind watermarking are appreciated through the values of the evaluation parameters which are the peak signal-to-noise ratio (PSNR) and the correlation coefficient (CC), and by the visual observation of the extracted watermarks before and after attacks. The values of these parameters show that this successive hybrid algorithm is robust against some conventional attacks.展开更多
Nanocapsules (NC) of antioxidant rich fraction of roasted <span>Moringa </span>leaves were prepared using emulsion coacervation technique with alginate (ALG) and/or chitosan (CTS) as biopolymers. NC were c...Nanocapsules (NC) of antioxidant rich fraction of roasted <span>Moringa </span>leaves were prepared using emulsion coacervation technique with alginate (ALG) and/or chitosan (CTS) as biopolymers. NC were characterized based on particle size, polydispersity index (PDI), zeta potential, encapsulation efficiency (EE) and loading capacity (LC). Substituting CTS with ALG in NC caused a reduction in particle size and PDI, and enhanced EE. Mean particle size dropped from 1209 nm in 1:3 to 413 nm in 3:1 ALG/CTS-NC;PDI decreased from 0.9% to 0.2% and zeta potential from </span></span><span><span><span style="font-family:"">-</span></span></span><span><span><span style="font-family:"">5.4 to </span></span></span><span><span><span style="font-family:"">-</span></span></span><span><span><span style="font-family:"">28.1 mV. </span></span></span><span><span><span style="font-family:"">The </span></span></span><span><span><span style="font-family:"">highest EE (87.6%) and LC (13%) were obtained with ALG-CTS-NC (3:1). ALG-NC were spherical while both CTS and ALG-CTS-NC were ovoid. ALG and ALG-CTS-NC were oil/water emulsions while CTS-NC formed water/oil emulsions. 60% and 70% of bioactives in ALG-CTS-NC (3:1) were released in simulated gastric and intestinal fluids respectively after 400 min. Release of antioxidants from NC is concentration-dependent (First order model) and involves simultaneously diffusion (Higuchi model), swelling (korsmeyer-Peppas model) and erosion (Hixson-Crowell model) mechanisms.展开更多
The JPEG2000 still image compression standard, while providing a remedy for the many shortcomings of its predecessor JPEG, is still slow to establish itself on the Internet. This problem is mainly due to the complexit...The JPEG2000 still image compression standard, while providing a remedy for the many shortcomings of its predecessor JPEG, is still slow to establish itself on the Internet. This problem is mainly due to the complexity of the COder-DECoder (CODEC) which implies its non-adoption by large firms and platforms in the field of image acquisition, processing and transmission. Indeed, the encoding and decoding process consumes a lot of CPU, memory and energy resources and takes a lot of computing time. The objective of this paper is to propose a model for decoding jpeg2000 on lightweight devices running on the Android mobile operating system. This implementation uses coroutines, which are a lightweight process model with reduced resource consumption costs compared to conventional AsyncTask threadsets. The model minimizes decoding time while minimizing CPU and memory usage, resulting in a fast and energetically economical decoded image. The results of integrating the coroutines from the main thread into the decoding process instead of the AsyncTask from the main thread produced better performance in terms of computation time, CPU and memory utilization. Indeed, the use of our model has led to a gain of around 23.41% in execution time, 9.8% in CPU utilization rate and 18.56% in memory utilization rate, compared to the model proposed in the literature which uses the threads.展开更多
Bio-glycerol was synthesized from Cameroon palm kernel oil (PKO) through the transesterification procedure. Palm kernel oil extracted from palm kernel seeds using mechanical expression and solvent extraction was purif...Bio-glycerol was synthesized from Cameroon palm kernel oil (PKO) through the transesterification procedure. Palm kernel oil extracted from palm kernel seeds using mechanical expression and solvent extraction was purified and characterized by physico-chemical methods and used in the transesterification process to give biodiesel and bio-glycerol. The biodiesel was purified and characterized as reported in previous articles. Our focus in this article is on glycerol, an important by-product of the transesterification process which has potential pharmaceutical, cosmetic and engineering applications. The bio-glycerol was purified by acidification and the purified glycerol was subjected to physical and chemical characterization. The specific gravity of glycerol was obtained as 1.2 kg/L, viscosity at 40°C gave 1500 cSt and 500 cSt at 100°C;pH was 7.4;the flash point was 160°C, and the ASTM color was 2.0 before purification and zero after purification. The sulfur content was 0.016%w/v. This sulfur content is low thus posing no environment threat. The chemical composition of the synthesized bio-glycerol determined using IR spectroscopy and gas chromatography-mass spectrometry (GC-MS) confirmed the known chemical structure of glycerol. The purification and analysis of bio-glycerol is important as it can find applications in the pharmaceutical, cosmetic and food industries inter alia.展开更多
The industrial production of most food and probiotic products often requires processing involving high temperatures and physiological stress causing loss of viability of probiotic microbial strains. The viability and ...The industrial production of most food and probiotic products often requires processing involving high temperatures and physiological stress causing loss of viability of probiotic microbial strains. The viability and stability of probiotic strains is a key determinant of their efficacy during administration in human and animal. Thermotolerance is actually a very important feature for probiotic undergoing industrial processing. This paper aimed at assessing the effect of some mineral salts on the thermotolerance and the probiotic properties of lactobacilli isolated from curded milk produced in Mezam Division, Cameroon. Lactobacilli were isolated by pour plate method on de Man Rogosa and Sharpe (MRS) agar. Lactobacilli were selected based on their ability to suppress in-vitro and in-vivo food borne pathogenic bacteria;Salmonella enterica serovar Enteridis and Esherichia coli. Inhibitory activities against these food borne pathogens were performed by disc diffusion method on Mueller Hinton agar. In-vivo inhibition of Salmonella was achieved using oral administration by gavage of (1.0 × 109 CFU/ml) of selected probiotic strain suspended in sterile water. Thermotolerance was assessed by measuring the survival rate of the strain after heating at various temperatures in the presence and absence of mineral salts. Resistance to bile was determined by measuring the survival rate of probiotics after incubation in the presence of oxgallbille and mineral salts. Two catalase negatives isolates were selected based on their capacity to exhibit inhibitory activities in-vitro and in-vivo against food borne pathogens. They were identified as strain of Lactobacillus casei (LS3) and Lactobacillus plantarum (LM4). These strains exhibited significant reduction (P Salmonella count in caeca swabs of infected chick model. The calcium and magnesium salts increased significantly (P < 0.05) the thermo-tolerance and resistance to bile of probiotic strains studied. These results suggested that calcium and magnesium could be used to monitor the viability of probiotic strains in probiotic products.展开更多
In this paper, a tractable solution is proposed to integrate, to a certain extent, market liquidity risk in the portfolio selection process. It is shown how an investor may take advantage of this additional risk sourc...In this paper, a tractable solution is proposed to integrate, to a certain extent, market liquidity risk in the portfolio selection process. It is shown how an investor may take advantage of this additional risk source within the standard mean-variance optimization framework, by in certain circumstances overcoming the pitfalls of illiquidity and in others seizing a liquidity premium. Bid prices appear effective to capture liquidity risk. The efficient frontier conceived with bid prices consists of mean-variance optimal allocations that cover more liquid stocks （large caps） under stressed market conditions and less liquid stocks （small caps） under normal conditions.展开更多
Particle size fractionation by sieving is used to optimize antioxydant potential of natural substances. The aim of the present study was to evaluate particle size effects on antioxidant and hepatoprotective potential ...Particle size fractionation by sieving is used to optimize antioxydant potential of natural substances. The aim of the present study was to evaluate particle size effects on antioxidant and hepatoprotective potential of Eucalyptus camaldulensis essential oils (EO) on CCl<sub>4</sub>-induced hepatic damage in Wistar rats. Animals were daily orally treated with the EOs extracted by hydrodistillation from powder sieved at four particle sizes (≥355, 200 - 355, 100 - 200, ≤100 μm) and those of the unsieved powder at dose of 50 mg/Kg for 7 days. Compounds that are evaluated for these activities are hydrocarbons and oxygenated terpenes that were identified and quantified by GC/MS. Activities of enzymes markers of hepatocellular damage in serum and antioxidant enzymes in the liver homogenates were measured. In this research, EOs significantly prevented the increase in serum ALT and AST (p < 0.05), total cholesterol, triglyceride and LDL-cholesterol level in acute liver damage induced by CCl<sub>4</sub> and significant increase level of plasma HDL-cholesterol. Also, significantly (p < 0.05) decreased the extent of malondialdehyde (MDA) formation and elevated the activities of superoxide dismutase (SOD) and catalase (CAT) liver in comparison to negative control group. The best antioxidant and hepatoprotective activities were those of EOs from two fine powder fractions (≤100 μm and 100 - 200 μm) was correlated to their high concentration in oxygenated terpenes (70.9% and 46.4%, respectively), when compared to the large particles (200 - 355 μm and ≥355 μm, with 33.3% and 41.8%, respectively) and unsieved powder (37.4%).展开更多
We propose and analyze an epidemiological model to evaluate the effectiveness of bed nets as a prophylactic measure in malaria-endemic areas. The main purpose in this work is the modeling of the aggressiveness of anop...We propose and analyze an epidemiological model to evaluate the effectiveness of bed nets as a prophylactic measure in malaria-endemic areas. The main purpose in this work is the modeling of the aggressiveness of anopheles mosquitoes relative to the way humans use to protect themselves against bites of mosquitoes. This model is a system of several differential equations: the number of equations depends on the particular assumptions of the model. We compute the basic reproduction number, and show that if, the disease free equilibrium (DFE) is globally asymptotically stable on the non-negative orthant. If, the system admits a unique endemic equilibrium (EE) that is globally and asymptotically stable. Numerical simulations are presented corresponding to scenarios typical of malaria-endemic areas, based on data collected in the literature. Finally, we discuss the relative effectiveness of different kinds of bed nets.展开更多
文摘Boscia aqueous extract. senegalensis on hyperglycemia, hyperlipidemia and oxidative stress induced in rats. The aqueous extract was prepared from B. senegalensis seed powders under the extraction conditions: time (10 min), temperature (55˚C) and the ratio of mass of flour/volume of water (3/10 g/mL). Male wistar rats aged 6 to 8 weeks were acclimated and divided into 8 groups of 5 rats each: two normal control groups which received a normal standard diet (3810 kcal/kg), and six test groups which were subjected to a hyperlipidemic diet (5310 Kcal/kg). All groups of animals were fed in this manner for 8 weeks to induce hyperglycemia, hyperlipidemia and oxidative stress. After induction the animals were treated either with distilled water for the normal and negative control groups or with atorvastatin for the positive control group or with the extract of B. senegalensis. (125, 250 and 500 mg/kg) for the test groups. Fasting blood glucose was taken every 7 days during induction. After sacrifice, biochemical and oxidative stress parameters were measured. The aqueous extract of B. senegalensis significantly decreased (p B. senegalensis at a dose of 500 mg/kg has the capacity to reduce blood sugar, improve the quality of the lipid profile and reduce oxidative stress. Thus, the results reveal that the aqueous extract of B. senegalensis has powerful hypoglycemic, hypolipidemic and antioxidant properties.
文摘Cardiovascular diseases are serious pathologies that affect an increasing number of people. Several preventive measures are generally used, including supplementing of oils in foods. Our objective was to compare the effects of Tetracarpidum conophorum oil (TC) and corn oil (CO) on serum lipid profiles of normal male rats. 42 Wistar rats were divided into 7 groups. Diets included TC oil (groups TC5, TC10 and TC20) and corn oil (groups CO5, CO10 and CO20) in proportions of 5%, 10% and 20%, with a control group (T). After 5 weeks of feeding, several parameters were measured during and after the study, including body weight, food intake and organ weights (kidney, liver and fat). Lipid profiles (total cholesterol, TG, HDL and LDL), glucose and protein levels were measured in the serum. The increase in body mass was inversely proportional to the amount of oil in the food. The decrease in body mass and adiposomatic index of group TC10 was significant (p < 0.05) compared with the other groups. The lowest glycaemia (64.17 ± 5.14 mg/dl) was noted with the diet containing 20% TC oil. A significant reduction in total cholesterol, LDL fraction and blood triglycerides was observed in the groups supplemented with TC and corn oils compared to controls. Results were also more beneficial for the TC10 group. HDL-cholesterol levels were significantly higher (p < 0.05) in the oil-supplemented groups than in the control group. Castelli’s risk indices decrease significantly (p < 0.05) with increasing oil content for TC. The oils had no impact on blood protein contents. One can conclude that a diet containing 10% crude oil from TC kernels could prevent or alleviate cardiovascular diseases and glycemia.
文摘The production and consumption of avocado pears generates tons of wastes, mainly the pear peels which are usually discarded, although they have been reported to contain important phyto-chemicals with biological activities. The adverse health effect associated with the consumption of saturated lipid based foods has ignited research on reformulation of lipid based foods to eliminate Trans Fatty Acids (TFAs). This study was thus aimed at the extraction and characterization of oil from Avocado Peels (APO) and evaluation of the quality of margarine produced from it. Five verities of pear were used for oil extraction by soxhlet method and physiochemical, oxidative, functional and antioxidant characterization was done. Margarines were formulated using a central composite design using oil blends of APO and Virgin Coconut Oil (VCO) with an oil ratio of 10:90, 40:60, 70:30 respectively, varied blending speed, blending time, and chitosan concentration. Samples were characterized and the effect of process parameters on the physiochemical and functional properties of the margarine studied. Optimized conditions were used to produce samples for sensory evaluation. Color, spreadability, aroma, taste and general acceptability was evaluated using ranking difference test. The results showed that the yield, density, and iodine values of APOs oils ranged from 14.91 ± 0.18 to 11.76 ± 0.46;0.93 ± 0.001 to 0.99 ± 0.1;46.63 ± 1.70 to 52.4 ± 0.63, their acid values, TBA and PV values ranged from 1.42 ± 0.39 to 1.97 ± 0.5;0.11 ± 0.002 to 0.18 ± 0.04;and 2.72 ± 0.14 to 4.43 ± 0.36 respectively, with Brogdon avocado peel variety having the overall best properties prepared blends of trans-free APO margarines showed that increase in APO ratio decreased melting point, increased oxidative stability and reduced moisture content of margarine samples. Chitosan addition leads to decrease moisture content and increase functional properties. VCO lead to increase in phenolic and flavonoid content of the margarines. Samples were spreadable and palatable with R20 being most palatable and the most accepted being R26 with a mean score of 7.07 ± 0.70. Decrease in color intensity increased acceptability. This study therefore demonstrated that avocado peel waste biomass can be valorized by using it as raw material for oil extraction, which can serve as good material for the production of trans-free margarines with good oxidative stability, functional and antioxidant properties.
文摘The objective of this work is to improve the physical and mechanical properties of stabilized earth blocks (BTC) used in construction in the Ndé department of Cameroon. To achieve this, two stabilizers, cement and sawdust, were used at varying percentages of 0%, 4%, 6%, and 8%. Physical characterization tests, including natural water content, specific weight, jar test, Protor, and Atterberg limits, were conducted. Additionally, mechanical tests, such as compression and three-point bending, were performed. The results show that as the amount of stabilizer increases, the density of BTC decreases. The samples with 8% sawdust have the highest density, while those without stabilizers have the lowest. Porosity decreases as sawdust and cement content increases, with smaller values observed in samples with 8% sawdust or cement. Our tests indicate that blocks stabilized with cement have slightly higher compressive strength than those stabilized with sawdust. However, the water absorption rate increases with higher sawdust content.
基金supported in part by funds from the International Foundation for Science (IFS) (agreement number C/5262-1)
文摘Information about the type of gene action governing the inheritance of cowpea seed flavonoid content and antioxidant activity is prerequisite for starting an effective breeding program for developing improved varieties. For this purpose, half-diallel crosses among seven diverse parents were made. The homozygous parents and 21 F1 hybrids were evaluated at Maroua in the Sudano-Sahelian zone of Cameroon using a randomized complete block design with three replicates. Flour samples produced from decorticated seeds were used for biochemical analysis. Analysis of variance showed significant differences(P < 0.001) among genotypes for the studied traits with ranges of 363.6–453.9 mg rutin equivalent per 100 g dry weight(DW) for total flavonoids, 13.38–30.73 mg ascorbic acid equivalent per 1 g DW for ferric iron reducing activity, 70.98–266.93 mg trolox equivalent per 100 g DW for 2,2-diphenyl-1-picrylhydrazyl(DPPH) free radical scavenging activity, and 90.93–370.62 mg trolox equivalent per 100 g DW for 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS) free radical scavenging activity. Both additive and non-additive gene effects were significant in the genetic control of these traits, but dominance variance was greater than additive variance. The traits were mainly controlled by overdominance model suggesting a selection in the delayed generations.Broad- and narrow-sense heritability estimates varied from 0.90 to 0.99 and from 0.12 to 0.45,respectively. The variances due to both general and specific combining ability were highly significant for all studied traits. Recessive alleles had positive effects on DPPH and ABTS scavenging activities, whereas dominant alleles had positive effects on flavonoid content and ferric iron reducing activity. These results could help cowpea breeders to improve the antioxidant potential of cowpea seeds by appropriate selection.
文摘Maintenance of glycemic control is important in preventing diabetes and its associated complications. Considering the current recommended approach for the use of functional foods and their bioactive components in the prevention and management of diabetes, the aim of this study was to determine the antihyperglycemic effect of Moringa oleifera functional tea in rat models and in normoglycemic human volunteers using the oral glucose tolerance test (OGTT). Moringa tea prepared by extracting Moringa leaf powder in distilled water (1:20 mg/ml) at 97°C for 30 min was administered at different doses to male Wistar rats and human volunteers prior to glucose loading. Blood glucose was measured at intervals of 30 min for 150 min. Consumption of Moringa tea prior to glucose loading suppressed the elevation in blood glucose in all cases compared to controls that did not receive the tea initially. The degree and pattern of decrease however, were dose dependent. In rats, intermediate doses of 20 ml/kg BW were more effective in reducing blood glucose overall (18.2%) vs 13.3% and 6% at doses of 10 and 30 ml/kg BW respectively. In humans, the final decrease in blood glucose was not significantly different for high 400 ml (19%) and low 200 ml (17%) doses. Of interest here was the pattern of decrease, being significantly higher (p < 0.05) at 30 min with 200 ml (22.8%) than with 400 ml (17.9%). It is suggested that low doses exert their antihyperglycemic effect more at intestinal level by inhibiting glucose absorption, whereas high doses exert their effect more in circulation. We conclude that Moringa oleifera tea has potential as a functional food in the management of hyperglycemia.
文摘The project consists in the implementation of a biocomposite based on tannin resin and natural rubber matrices with the bast fibres of <i>Triumfetta cordifolia </i>A.Rich.“<i>Okong</i>” from the equatorial region of Cameroon as reinforcement. A study of this still little known fibre is necessary. This paper evaluates the physico-chemical and mechanical characteristics of the fibers. The fibers are extracted by us. A series of experiments is conducted for this purpose: morphological observation with a scanning electron microscope (SEM);density evaluation with a helium pycnometer;absorption rate evaluation according to the protocol available in the literature, Fourier Transform Infrared Spectrometry (FT-IR), chemical composition evaluation according to ASTM 1972 and ASTM 1977 standards, thermogravimetric analysis (TGA) and tensile tests on fiber bundles according to NF T25-501-3. The results show that the fiber is made up of several elementary fibers with oval cross-sections. A density of 1.477g/cm<sup>3</sup> close to that of hemp. These fibers have a water absorption rate of 342.5%, which correlates with the presence of free hydroxyl functional groups obtained from the spectrometry study (FT-IR). Chemical analysis reveals that the fiber is made up of celluloses (44.4%), hemicelluloses (30.8%), lignins (18.9%), pectins (3.3%), waxes (0.5%) and minerals (2.1%). In addition, we learn that the fibers studied dehydrate at 11.49%, showinga notable thermal stability around 235°C with a peak thermal decomposition of cellulose located at 420°C. In terms of mechanical behaviour, the results reveal that the fibers offer a Young’s modulus in traction of 12.4 ± 6.9 GPa, a tensile strength of 526 ± 128 MPa and an elongation at break of 2.25%. The information thus obtained makes it possible to place these fibers in the same fiber group as flax and jute. They could therefore be used for the same types of applications. They also inform us that these fibers can withstand the temperatures of composite shaping by thermocompression.
基金supported in part by funds from International Foundation for Science(C/5262-1)
文摘The content of soluble sugar in cowpea(Vigna unguiculata L. Walp.) seeds is important for their acceptability to consumers. The objective of this study was to evaluate the genetic control of soluble sugar content in cowpea using diallel analysis. For this purpose,half-diallel crosses were made among seven diverse parents. The amount of total soluble sugar was estimated by the phenol sulfuric acid reagent method and reducing sugar were measured by the DNS(3,5-dinitrosalicylic acid) reagent method. The total soluble sugar ranged from 11.12(VYA) to 40.79 mg g^(-1)(IT93 K-693-2) with a mean of 22.31 mg g^(-1).Reducing soluble sugar showed a mean value of 9.11 mg g^(-1) and ranged from 13.61(TVx3236) to 4.98 mg g^(-1)(Lori niebe). Diallel analysis showed that both additive and non-additive gene effects were significant in the genetic control of these traits. However,dominance variance was greater than additive variance for soluble sugar. The traits were controlled mainly by an overdominance model, suggesting the advantage of delaying selection to later generations. Soluble sugar content was found to be highly heritable, with broad-sense heritability ranging from 0.987 to 0.976. Narrow-sense heritability ranged from0.154 to 0.422 and revealed the lower importance of additive variance. Parents and F_1 hybrids differed significantly on the basis of their general and specific combining abilities,respectively. Recessive alleles had positive effects on total soluble sugar and reducing soluble sugar. These results could help cowpea breeders improve the acceptability of cowpea seeds and cowpea-based foods by appropriate selection.
文摘Dried leaves of <i><span style="font-family:Verdana;">Eucalyptus</span></i> <i><span style="font-family:Verdana;">camaldulensis</span></i><span style="font-family:Verdana;"> were finely grinded and fractionated</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> by sieving into four granulometric classes (<100 μm, 100 - 200 μm, 200 - 355 μm and >355 μm). The obtained powder fractions were used for essential oil (EO) extraction by hydrodistillation and their phytochemical profile and </span><i><span style="font-family:Verdana;">in</span></i> <i><span style="font-family:Verdana;">vitro</span></i><span style="font-family:Verdana;"> antioxidant activities were evaluated. The mother powder (unsieved powder) was used for comparison. Particle size exerted a significant influence (</span><i><span style="font-family:Verdana;">p</span></i><span style="font-family:Verdana;"> < 0.05) on the phytochemical composition and </span><i><span style="font-family:Verdana;">in</span></i> <i><span style="font-family:Verdana;">vitro</span></i><span style="font-family:Verdana;"> antioxidant prop</span><span><span style="font-family:Verdana;">erties of the EOs. Comparatively, the mother powder had the highest contents of </span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;">-pinene (55.6%), camphene (3.4%) and limonene (3.7%), while 1,8-cineole (26.6% and 22.4%), </span></span><span style="font-family:Verdana;">exo-fenchol (5.6% and 3.5%), </span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;">-campholenol (4.2% and 3.4%), L-trans-pinocarveol (5.5% and 2.7%), L-borneol (12.6% and 6.8%) and </span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;">-terpineol (16.4% and 7.6%) are the main compounds of EOs from the <100 μm and 100 - 200 μm fractions, respectively. The antioxidant activities of the EOs revealed higher radical-scavenging activities DPPH (90.62% and 70.46%) and ABTS (89.59% and 73.31%) for finer fractions (<100 μm and 100 - 200 μm, respectively). The best reducing power (36.15% and 34.27%) were also found in these finer powder fractions which improved by more than 2 times the value of mother powder (reducing power of 17.01%). These results suggest that grinding followed by sieve fractionation concentrates the majority of antioxidant phytochemicals in the EOs of the finer powder fractions of </span><i><span style="font-family:Verdana;">E.</span></i> <i><span style="font-family:Verdana;">camaldulensis</span></i><span style="font-family:Verdana;"> leaves. Finer powders could be used as functional ingredients in food formulations for the management of chronic diseases.</span></span>
文摘Computer grids are infrastructures in which heterogeneous and distributed resources offer very high computing or storage performance. If they offer extreme computing performance, they are also subject to the appearance of many failures related to this type of architecture. While performing tasks, if the response time of a node in the system incomprehensibly exceeds the requirements of the specifications, the node experiences an omission failure. The task running in the failed node will be unavailable until the node resumes normal activity. Waiting not being a possible solution, many fault tolerance methods have been proposed. Despite this large number of fault tolerance methods on offer, computer grids are still prone to many failures by omission. In this work, a numerical study of the failures by omission which occur in the calculation grids during the execution of the tasks was carried out and a model allowing anticipating its failures was proposed with the formalism PDEVS (Parallel Discret EVent system Specification).
文摘In African communities, traditional beer drinking remains a unifying factor within its populations both socially, commercially, culturally, politically, in health and nutrition and for some ritual practices. In this research a field survey was carried out to investigate the consumption of corn beer and in particular <i>Nkang</i> in the North-West Region of Cameroon. The tools that were employed to carry out these investigations included face-to-face interviews and the use of properly designed questionnaires. Results from the survey showed that three types of maize-based beverages are drunk in the North-West Region of Cameroon, which are locally called <i>Kwacha</i> (whitish, most viscous and most turbid), <i>Sha-ah</i> (cream white, viscous and turbid) and <i>Nkang</i> (dark brown, least viscous and least turbid) in terms of colour, viscosity and turbidity. The percentage awareness of the existence of these beers from the sampled population gave the following values;60.9% for <i>Kwacha</i>, 100% for <i>Sha-ah</i> and 89.1% for <i>Nkang</i>. Nonetheless, 54.5% of the 60.9% of those who were aware of the existence of <i>kwacha</i> had at least tasted it. Also 98.2% out of the 100% for <i>Sha-ah</i> and 85.5% out of 89.1% for <i>Nkang</i> had tasted them, too. <i>Nkang</i> was found to be the most preferred to <i>Sha-ah</i> then <i>Kwacha</i> in that order by the consumers since <i>Nkang</i> is very tasteful, least alcoholic, least turbid, least viscous, has the most attractive colour than the others, has a significant impact on the culture of some localities in this region and as well as it is natural and nutritious. However, <i>Nkang</i> as well as the other two has varying organoleptic properties, unsatisfactory conservation and short shelf-life. Hence are consumed within a short period of time from their production. Because of the low alcoholic content of <i>Nkang</i>, the beverage is consumed by both adults (most elderly), children, those who have health problems and it is mostly preferred by some Christians though not frequently seen in the markets. It was equally observed that the little quantity of <i>Nkang</i> found in the markets is of poor quality which keeps dropping everyday thus an indication of its risk becoming extinct. Therefore, if <i>Nkang</i> is clarified and its quality improved, the problems can be solved as even attested by the consumers who say they will buy at even a higher price if clarify. As well as those who want it for their cultural reasons do not want it to face out too.
文摘This paper presents the optimization of the PV/battery system including extrapolation of the electrical demand. Matlab software was chosen to implement the algorithm. PVC, the number of PV modules and battery capacity increase with increasing electrical demand. This makes it possible to predict the device according to the electrical demand. Particle swarm optimization is used to minimize the total cost of the system over 20</span><span style="font-size:10.0pt;font-family:""> </span><span style="font-size:10.0pt;font-family:"">year</span><span style="font-size:10.0pt;font-family:"">s</span><span style="font-size:10.0pt;font-family:"">. The average cost of energy is $0.369/kWh.
文摘In this paper, we present a new robust hybrid algorithm combining successively chaotic encryption and blind watermarking of images based on the quaternionic wavelet transform (QWT) to ensure the secure transfer of digital data. The calculations of the different evaluation parameters have been performed in order to determine the robustness of our algorithm to certain attacks. The application of this hybrid algorithm on CFA (Color Filter Array) images, allowed us to guarantee the integrity of the digital data and to propose an autonomous transmission system. The results obtained after simulation of this successive hybrid algorithm of chaotic encryption and then blind watermarking are appreciated through the values of the evaluation parameters which are the peak signal-to-noise ratio (PSNR) and the correlation coefficient (CC), and by the visual observation of the extracted watermarks before and after attacks. The values of these parameters show that this successive hybrid algorithm is robust against some conventional attacks.
文摘Nanocapsules (NC) of antioxidant rich fraction of roasted <span>Moringa </span>leaves were prepared using emulsion coacervation technique with alginate (ALG) and/or chitosan (CTS) as biopolymers. NC were characterized based on particle size, polydispersity index (PDI), zeta potential, encapsulation efficiency (EE) and loading capacity (LC). Substituting CTS with ALG in NC caused a reduction in particle size and PDI, and enhanced EE. Mean particle size dropped from 1209 nm in 1:3 to 413 nm in 3:1 ALG/CTS-NC;PDI decreased from 0.9% to 0.2% and zeta potential from </span></span><span><span><span style="font-family:"">-</span></span></span><span><span><span style="font-family:"">5.4 to </span></span></span><span><span><span style="font-family:"">-</span></span></span><span><span><span style="font-family:"">28.1 mV. </span></span></span><span><span><span style="font-family:"">The </span></span></span><span><span><span style="font-family:"">highest EE (87.6%) and LC (13%) were obtained with ALG-CTS-NC (3:1). ALG-NC were spherical while both CTS and ALG-CTS-NC were ovoid. ALG and ALG-CTS-NC were oil/water emulsions while CTS-NC formed water/oil emulsions. 60% and 70% of bioactives in ALG-CTS-NC (3:1) were released in simulated gastric and intestinal fluids respectively after 400 min. Release of antioxidants from NC is concentration-dependent (First order model) and involves simultaneously diffusion (Higuchi model), swelling (korsmeyer-Peppas model) and erosion (Hixson-Crowell model) mechanisms.
文摘The JPEG2000 still image compression standard, while providing a remedy for the many shortcomings of its predecessor JPEG, is still slow to establish itself on the Internet. This problem is mainly due to the complexity of the COder-DECoder (CODEC) which implies its non-adoption by large firms and platforms in the field of image acquisition, processing and transmission. Indeed, the encoding and decoding process consumes a lot of CPU, memory and energy resources and takes a lot of computing time. The objective of this paper is to propose a model for decoding jpeg2000 on lightweight devices running on the Android mobile operating system. This implementation uses coroutines, which are a lightweight process model with reduced resource consumption costs compared to conventional AsyncTask threadsets. The model minimizes decoding time while minimizing CPU and memory usage, resulting in a fast and energetically economical decoded image. The results of integrating the coroutines from the main thread into the decoding process instead of the AsyncTask from the main thread produced better performance in terms of computation time, CPU and memory utilization. Indeed, the use of our model has led to a gain of around 23.41% in execution time, 9.8% in CPU utilization rate and 18.56% in memory utilization rate, compared to the model proposed in the literature which uses the threads.
文摘Bio-glycerol was synthesized from Cameroon palm kernel oil (PKO) through the transesterification procedure. Palm kernel oil extracted from palm kernel seeds using mechanical expression and solvent extraction was purified and characterized by physico-chemical methods and used in the transesterification process to give biodiesel and bio-glycerol. The biodiesel was purified and characterized as reported in previous articles. Our focus in this article is on glycerol, an important by-product of the transesterification process which has potential pharmaceutical, cosmetic and engineering applications. The bio-glycerol was purified by acidification and the purified glycerol was subjected to physical and chemical characterization. The specific gravity of glycerol was obtained as 1.2 kg/L, viscosity at 40°C gave 1500 cSt and 500 cSt at 100°C;pH was 7.4;the flash point was 160°C, and the ASTM color was 2.0 before purification and zero after purification. The sulfur content was 0.016%w/v. This sulfur content is low thus posing no environment threat. The chemical composition of the synthesized bio-glycerol determined using IR spectroscopy and gas chromatography-mass spectrometry (GC-MS) confirmed the known chemical structure of glycerol. The purification and analysis of bio-glycerol is important as it can find applications in the pharmaceutical, cosmetic and food industries inter alia.
文摘The industrial production of most food and probiotic products often requires processing involving high temperatures and physiological stress causing loss of viability of probiotic microbial strains. The viability and stability of probiotic strains is a key determinant of their efficacy during administration in human and animal. Thermotolerance is actually a very important feature for probiotic undergoing industrial processing. This paper aimed at assessing the effect of some mineral salts on the thermotolerance and the probiotic properties of lactobacilli isolated from curded milk produced in Mezam Division, Cameroon. Lactobacilli were isolated by pour plate method on de Man Rogosa and Sharpe (MRS) agar. Lactobacilli were selected based on their ability to suppress in-vitro and in-vivo food borne pathogenic bacteria;Salmonella enterica serovar Enteridis and Esherichia coli. Inhibitory activities against these food borne pathogens were performed by disc diffusion method on Mueller Hinton agar. In-vivo inhibition of Salmonella was achieved using oral administration by gavage of (1.0 × 109 CFU/ml) of selected probiotic strain suspended in sterile water. Thermotolerance was assessed by measuring the survival rate of the strain after heating at various temperatures in the presence and absence of mineral salts. Resistance to bile was determined by measuring the survival rate of probiotics after incubation in the presence of oxgallbille and mineral salts. Two catalase negatives isolates were selected based on their capacity to exhibit inhibitory activities in-vitro and in-vivo against food borne pathogens. They were identified as strain of Lactobacillus casei (LS3) and Lactobacillus plantarum (LM4). These strains exhibited significant reduction (P Salmonella count in caeca swabs of infected chick model. The calcium and magnesium salts increased significantly (P < 0.05) the thermo-tolerance and resistance to bile of probiotic strains studied. These results suggested that calcium and magnesium could be used to monitor the viability of probiotic strains in probiotic products.
文摘In this paper, a tractable solution is proposed to integrate, to a certain extent, market liquidity risk in the portfolio selection process. It is shown how an investor may take advantage of this additional risk source within the standard mean-variance optimization framework, by in certain circumstances overcoming the pitfalls of illiquidity and in others seizing a liquidity premium. Bid prices appear effective to capture liquidity risk. The efficient frontier conceived with bid prices consists of mean-variance optimal allocations that cover more liquid stocks （large caps） under stressed market conditions and less liquid stocks （small caps） under normal conditions.
文摘Particle size fractionation by sieving is used to optimize antioxydant potential of natural substances. The aim of the present study was to evaluate particle size effects on antioxidant and hepatoprotective potential of Eucalyptus camaldulensis essential oils (EO) on CCl<sub>4</sub>-induced hepatic damage in Wistar rats. Animals were daily orally treated with the EOs extracted by hydrodistillation from powder sieved at four particle sizes (≥355, 200 - 355, 100 - 200, ≤100 μm) and those of the unsieved powder at dose of 50 mg/Kg for 7 days. Compounds that are evaluated for these activities are hydrocarbons and oxygenated terpenes that were identified and quantified by GC/MS. Activities of enzymes markers of hepatocellular damage in serum and antioxidant enzymes in the liver homogenates were measured. In this research, EOs significantly prevented the increase in serum ALT and AST (p < 0.05), total cholesterol, triglyceride and LDL-cholesterol level in acute liver damage induced by CCl<sub>4</sub> and significant increase level of plasma HDL-cholesterol. Also, significantly (p < 0.05) decreased the extent of malondialdehyde (MDA) formation and elevated the activities of superoxide dismutase (SOD) and catalase (CAT) liver in comparison to negative control group. The best antioxidant and hepatoprotective activities were those of EOs from two fine powder fractions (≤100 μm and 100 - 200 μm) was correlated to their high concentration in oxygenated terpenes (70.9% and 46.4%, respectively), when compared to the large particles (200 - 355 μm and ≥355 μm, with 33.3% and 41.8%, respectively) and unsieved powder (37.4%).
文摘We propose and analyze an epidemiological model to evaluate the effectiveness of bed nets as a prophylactic measure in malaria-endemic areas. The main purpose in this work is the modeling of the aggressiveness of anopheles mosquitoes relative to the way humans use to protect themselves against bites of mosquitoes. This model is a system of several differential equations: the number of equations depends on the particular assumptions of the model. We compute the basic reproduction number, and show that if, the disease free equilibrium (DFE) is globally asymptotically stable on the non-negative orthant. If, the system admits a unique endemic equilibrium (EE) that is globally and asymptotically stable. Numerical simulations are presented corresponding to scenarios typical of malaria-endemic areas, based on data collected in the literature. Finally, we discuss the relative effectiveness of different kinds of bed nets.
