Collagenase was isolated from fish waste (a mixture of haddock, herring, ground fish and flounder) using a Tris-buffer system. The proteins in the crude extract were precipitated using ammonium sulfate (40% - 80%) and...Collagenase was isolated from fish waste (a mixture of haddock, herring, ground fish and flounder) using a Tris-buffer system. The proteins in the crude extract were precipitated using ammonium sulfate (40% - 80%) and purified with gel-filtration chromatography using Sephadex G-100. The results showed that the collagenase enzyme was produced as a latent enzyme and was activated with bovine trypsin and potassium thiocyanate (KSCN). The enzyme activity was affected by pH and temperature. Optimal enzyme activities were found at 35?C and a pH of 7.5 when insoluble collagene type I was used as substrate and the liberated amino acids were measured in relation to L-leucine in the presence of ninhydrin. The enzyme activity was completely inhibited by the action of ethylenediaminetetraacetic acid (EDTA) suggesting that the collagenase enzyme isolated from the fish waste is a metalloproteinase enzyme requiring metal ions for enzyme activity. Dialysis against KSCN decreased the enzyme total activity and increased its specific activity. Sodium dodecyl sulphate polyacryla-mide gel electrophoresis (SDS-PAGE) indicated that the purified procollagenase enzyme have only one band at molecular weight of 50 kilodaltons (kDa). When the enzyme was cleaved with trypsin, it was found to consist of two subunits: a large unit with a molecular weight of 50 kDa and a small unit with a molecular weight of 10 kDa.展开更多
This research aims to study the bio-adsorption process of two dyes,Cibacron Green H3G(CG-H3G)and Terasil Red(TR),in a single system and to bring them closer to the industrial textile discharge by a binary mixture of t...This research aims to study the bio-adsorption process of two dyes,Cibacron Green H3G(CG-H3G)and Terasil Red(TR),in a single system and to bring them closer to the industrial textile discharge by a binary mixture of two dyes(TR+CG-H3G).The Cockle Shell(CS)was used as a natural bio-adsorbent.The characterizations of CS were investigated by Fourier transform infrared(FTIR),X-ray diffraction(XRD),scanning electron microscopy(SEM),energy-dispersive X-ray spectroscopy(EDX)and Brunauer–Emmett–Teller(BET).The adsorption potential of Cockle Shells was tested in two cases(single and binary system)and determined by:contact time(0–60 min),bio-adsorption dose(3–15 g/L),initial concentration(10–300 mg/L),temperature(22–61°C)and pH solution(2–12).The study of bio-adsorption(equilibrium and kinetics)was conducted at 22°C.The kinetic studies demon-strated that a pseudo-second-order adsorption mechanism had a good correlation coefficient(R2≥0.999).The Langmuir isotherm modeling provided a well-defined description of TR and CG-H3G bio-adsorption on cockle shells,exhibiting maximum capacities of 29.41 and 3.69 mg/g respectively at 22°C.The thermodynamic study shows that the reaction between the TR,CG-H3G dyes molecules and the bio-adsorbent is exothermic,spontaneous in the range of 22–31°C with the aleatory character decrease at the solid-liquid interface.The study of selectivity in single and binary systems has been performed under optimal operating conditions using the industrial textile rejection pH(pH=6.04).CG-H3G dye is found to have a higher selectivity than TR in single(0–60 min)and binary systems with a range of 6–45 min,as shown by the selectivity measurement.It was discovered that CS has the capability to remove both CG-H3G and TR dyes in both simple and binary systems,making it a superior bio-adsorbent.展开更多
The increase in oil prices and greenhouse gas emissions has led to the search for substitutes for fossil fuels. In Cameroon, the abundance of lignocellulosic resources is inherent to agricultural activity. Production ...The increase in oil prices and greenhouse gas emissions has led to the search for substitutes for fossil fuels. In Cameroon, the abundance of lignocellulosic resources is inherent to agricultural activity. Production of bioethanol remains a challenge given the crystallinity of cellulose and the presence of the complex. The pretreatment aimed to solubilize the lignin fraction and to make cellulose more accessible to the hydrolytic enzymes, was done using the organosolv process. A mathematical modeling was performed to point out the effect of the temperature on the kinetics of the release of the reducing sugars during the pretreatment. Two mathematical model was used, SAEMAN’s model and Response surface methodology. The first show that the kinetic parameters of the hydrolysis of the cellulose and reducing sugar are: 0.05089 min<sup>-1</sup>, 5358.1461 J·mol<sup>-1</sup>, 1383.03691 min<sup>-1</sup>, 51577.6100 J·mol<sup>-1</sup> respectively. The second model was used. Temperature is the factor having the most positive influence whereas, ethanol concentration is not an essential factor. To release the maximum, an organosolv pre-treatment of this sub-strate should be carried out at 209.08°C for 47.60 min with an ethanol-water ratio of 24.02%. Organosolv pre-treatment is an effective process for delignification of the lignocellulosic structure.展开更多
This paper compares three methods for natural gas dehydration that are widely applied in industry：（1） absorption by triethylene glycol, （2） adsorption on solid desiccants and （3） condensation. A comparison is m...This paper compares three methods for natural gas dehydration that are widely applied in industry：（1） absorption by triethylene glycol, （2） adsorption on solid desiccants and （3） condensation. A comparison is made according to their energy demand and suitability for use. The energy calculations are performed on a model where 105 Nm3/h water saturated natural gas is processed at 30 °C. The pressure of the gas varies from 7 to 20 MPa. The required outlet concentration of water in natural gas is equivalent to the dew point temperature of -10 °C at gas pressure of 4 MPa.展开更多
It is necessary to understand all the prerequisites, which result in gas hydrate formation for safe design and control of a variety of processes in petroleum industry. Thermodynamic hydrate inhibitors (THIs) are norma...It is necessary to understand all the prerequisites, which result in gas hydrate formation for safe design and control of a variety of processes in petroleum industry. Thermodynamic hydrate inhibitors (THIs) are normally used to preclude gas hydrate formation by shifting hydrate stability region to lower temperatures and higher pressures. Sometimes, it is difficult to avoid hydrate formation and hydrates will form anyway. In this situation, kinetic hydrate inhibitors (KHIs) can be used to postpone formation of gas hydrates by retarding hydrate nucleation and growth rate. In this study, two kinetic parameters including natural gas hydrate formation induction time and the rate of gas consumption were experimentally investigated in the presence of monoethylene glycol (MEG), L-tyrosine, and polyvinylpyrrolidone (PVP) at various concentrations in aqueous solutions. Since hydrate formation is a stochastic phenomenon, the repeatability of each kinetic parameter was evaluated several times and the average values for the hydrate formation induction times and the rates of gas consumption are reported. The results indicate that from the view point of hydrate formation induction time, 2 wt% PVP and 20 wt% MEG aqueous solutions have the highest values and are the best choices. It is also interpreted from the results that from the view point of the rate of gas consumption, 20 wt% MEG aqueous solution yields the lowest value and is the best choice. Finally, it is concluded that the combination of PVP and MEG in an aqueous solution has a simultaneous synergistic impact on natural gas hydrate formation induction time and the rate of gas consumption. Furthermore, a semi-empirical model based on chemical kinetic theory is applied to evaluate the hydrate formation induction time data. A good agreement between the experimental and calculated hydrate formation induction time data is observed.展开更多
Jadomycin is an antibiotic that has shown activities against bacteria, yeasts and fungi as well as cytotoxic properties to cancer cells. Because of the wide range of its inhibitory actions, jadomycin shows promise as ...Jadomycin is an antibiotic that has shown activities against bacteria, yeasts and fungi as well as cytotoxic properties to cancer cells. Because of the wide range of its inhibitory actions, jadomycin shows promise as a novel antibiotic and cancer treatment drug. Streptomyces venezuelae are aerobic bacteria that produce jadomycin and the size of bacterial population can significantly affect the yield of jadomycin. Therefore, the bacterial population must be accurately measured in order to standardize the reproducibility of jadomycin production process. In this study, a dehydrogenase activity measurement test, using triphenyl tetrazolium chloride (TTC), was used to measure the dehydrogenase activity of Streptomyces venezuelae during growth in maltose-yeast extract-malt extract (MYM) broth. The aims were to evaluate the effectiveness of the test for measuring microbial growth and to study the effects of the test conditions (incubation time, incubation temperature and medium pH) on triphenyl formazan (TF) yield. The results showed that the TF yield was highly correlated to the optical density. The highest TF yield was observed at a pH of 6 at all incubation times and temperature. Lower TF yields were obtained at higher temperature (40 and 50oC) compared to those obtained at lower temperatures (22 and 30oC). The difference between the yields obtained at 22oC and 30oC were not significant. The differences between incubation time were also not significant. The recommended test conditions are an incubation time of 1 hour at a temperature of 30oC and a pH of 6 followed by three extractions using methanol.展开更多
Indentation and reciprocating wear tests are carried out to study dent and wear resistance of superelastic Ti-Ni alloys. The effect of loading rate on the superelastic behavior of TiNi under indentation loading is inv...Indentation and reciprocating wear tests are carried out to study dent and wear resistance of superelastic Ti-Ni alloys. The effect of loading rate on the superelastic behavior of TiNi under indentation loading is investigated and compared to a new generation of shape memory alloys, i.e., 60NiTi. Only limited amount of work has been done to investigate the dependency of superelasticity on loading rate of TiNi under localized compressive loads, but much work is directed towards understanding the effect of strain rate on tensile properties. Understanding the superelastic behavior helps to employ superelastic alloys in applications where high impact loading is expected as in bearings and gears. In the present study, it is found that dent resistance of Ti-Ni alloy is not significantly affected by loading rate (within the employed loading conditions). It has also been found that new-generation 60NiTi alloy exhibits superior wear and dent resistance, as well as higher hardness compared to equiatomic TiNi.展开更多
The effects of aeration rate and impeller speed on the concentrate sulfur grade and recovery for batch flotation of a complex sulphide ore were investigated. The relationships between the water recovery and solid entr...The effects of aeration rate and impeller speed on the concentrate sulfur grade and recovery for batch flotation of a complex sulphide ore were investigated. The relationships between the water recovery and solid entrainment were discussed. It is found that the solid entrainment is linearly related to the water recovery regardless of aeration rate and impeller speed, and the higher sulfur recovery at the aeration rate of 2 and 4 L/min for the impeller speed of 1 500 r/min is considered to be the contribution of true flotation. Finally, the sulfur recovery flux is correlated with the bubble surface area flux based on the froth image at the different aeration rates and impeller speeds.展开更多
The froth features in the batch flotation of a sulphide ore were investigated by using the digital image parameters of the froth, the small number emphasis(Nsne), the average grey level(Dagl) and the instability numbe...The froth features in the batch flotation of a sulphide ore were investigated by using the digital image parameters of the froth, the small number emphasis(Nsne), the average grey level(Dagl) and the instability number(Nins), under different conditions of impeller speeds and aeration rates. It is found that the value of Nsne is strongly dependent on the average bubble size of the froth and Dagl on the volume fraction of solid in the froth, and the froth features during the batch flotation are influenced by impeller speed and aeration rate. A kinetic model of the concentrate solid flux was developed which relates the flotation process to the image parameters, Nsne and Dagl of the froth and predictions are well consistent with the experimental data.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
In this work, the effect of the presence of nickel and lead in thermal decomposition of olive tree pruning (OTP), OTP-char and OTP-ashes was studied by thermogravimetry. Experiments were conducted in two kinds of atmo...In this work, the effect of the presence of nickel and lead in thermal decomposition of olive tree pruning (OTP), OTP-char and OTP-ashes was studied by thermogravimetry. Experiments were conducted in two kinds of atmosphere (nitrogen atmosphere and oxidizing atmosphere with 20% of O2) at a heating rate of 10 ℃/min. This investigation describes the chemical, physical and fuel properties of the OTP, which shows a similar composition to other lignocellulosic materials such as hazelnut husk and wood sawdust. In addition, SEM analysis indicated that OTP-char surface is higher than OTP surface with plenty of holes and channels. It makes the char an ideal support for metal retention specially for Pb metal (OTP retained 8.55 mg/g whereas OTP char retained 11.57 mg/g). On the other hand, metal retention occurred by adsorption or ion exchange, according to the IR spectrum of the samples. The results of thermogravimetric tests proved that the presence of lead did not have a strong effect on the decomposition of the samples, since TG and DTG curves were very similar. However, nickel increased the mass loss rate, accelerating the decomposition process, showing higher peaks in DTG curves. Additionally, for temperatures higher than 360 ℃, the volatilization of the samples was improved in the nickel-polluted sample, achieving a higher mass loss, getting more energy from the biomass and reducing the quantity of residues left after the process.展开更多
In this work,the properties of biochar produced from green macroalga Ulva intestinalis by pyrolysis were studied at temperatures of 300,500,and 700°C.This biochar was characterized in terms of multielemental comp...In this work,the properties of biochar produced from green macroalga Ulva intestinalis by pyrolysis were studied at temperatures of 300,500,and 700°C.This biochar was characterized in terms of multielemental composition,BET surface area,total pore volume,and biosorption properties toward phosphate ions.Biochar produced at 700°C-25 m2/g had the highest surface area.The kinetics and isotherms of sorption processes of phosphate ions as sorbate by these sorbents were investigated.Modified biochar was able to remove 84.3%of phosphate ions from wastewater,whereas non-modified biochar-only 40.6%.Hence,biochar enriched with phosphate ions can serve as a valuable soil amendment.Pot experiments performed on winter wheat(Triticum aestivum)with a 3%addition of dry Ulva intestinalis,pristine biochar,and Mg-modified biochar enriched with phosphate ions showed that these amendments stimulated plant growth(length and fresh weight of plants)as well as enlarging the chlorophyll content in leaves.Our results indicate that the production of biochar(pristine and Mg-impregnated)is a sustainable option to valorize the biomass of seaweeds,and to recycle phosphorus from wastewater.展开更多
The sugarcane bagasse fuel is an energetic deposit opportunity for thermal and electricity generation in sugar society.Combustion behaviors,essential for effective operation of these devices are a necessity.A 3D numer...The sugarcane bagasse fuel is an energetic deposit opportunity for thermal and electricity generation in sugar society.Combustion behaviors,essential for effective operation of these devices are a necessity.A 3D numerical model has been developed in the commercial software Ansys Fluent.According to the fuel density and particle variable,this model took into account both suspension and grate model combustion.The realizable k-ε turbulent model with the P-1 model shows its advantage of describing such king problems and has been applied on the numerical model.The contour of the temperature,spices and the particle trajectory provided a clear understanding of bagasse fuel combustion in the furnace as well,bagasse particle goes through from initial heating to char combustion and its conversion to ash.The results obtained were in accordance with those of the literature.These results could be used to analyze this inexpensive combustion process for looking for the effect of design parameter change on the furnace performance.展开更多
The reactivity between charged Li(Li_(0.115)Mn_(0.529)Ni_(0.339)Al_(0.017))O_(2)(Li-rich),single crystal Li(Ni_(0.8)Mn_(0.1)Co_(0.1))O_(2)(SC-NMC811),LiFePO_(4)(LFP) and LiMn_(0.8)Fe_(0.2)PO_(4)(LMFP) positive electro...The reactivity between charged Li(Li_(0.115)Mn_(0.529)Ni_(0.339)Al_(0.017))O_(2)(Li-rich),single crystal Li(Ni_(0.8)Mn_(0.1)Co_(0.1))O_(2)(SC-NMC811),LiFePO_(4)(LFP) and LiMn_(0.8)Fe_(0.2)PO_(4)(LMFP) positive electrodes at different states of charge(SOCs) and traditional carbonate-based electrolyte at elevated temperatures is systematically studied using accelerating rate calorimetry(ARC).The results show that the SOC greatly affects the thermal stability of the Li-rich and SC-NMC811 when traditional carbonate-based electrolyte is used.Although an increase in the SOC increases the energy density of lithium-ion cells,it also increases the reactivity between charged Li-rich and SC-NMC811 samples with electrolyte at elevated temperatures.In comparison with SC-NMC811,the Li-rich samples are much more stable at elevated temperatures,and the latter have higher specific capacity.SC-NMC811 samples are less reactive than traditional polycrystalline NMC811.Both LFP and LMFP samples show excellent thermal stability at elevated temperatures.The substitution of Fe by Mn in the olivine series positive materials does not impact the reactivity with electrolyte.展开更多
Fabrication of stable,reproducible and reusable reference electrodes for low energy and high-temperature steam splitting is of great interest for hydrogen fuel production without anthropogenic carbon dioxide(CO2)emiss...Fabrication of stable,reproducible and reusable reference electrodes for low energy and high-temperature steam splitting is of great interest for hydrogen fuel production without anthropogenic carbon dioxide(CO2)emission.This study has been conducted for the detection of suitable material for the fabrication of novel reference electrode.In the present scenario,this research is designed to fabricate a novel nickel reference electrode by using operating conditions of eutectic molten hydroxide(NaOH-KOH,49-51 mol%)at temperature 300℃in an ion-conducting membrane of alumina and mullite tube.Afterwards,the designed nickel reference electrode has been examined for its reusability and stability by using electrochemical technique and cyclic voltammetry.Five scans of cyclic voltammetry are performed for both membrane fabricated reference electrode.A slight positive shift in oxidation peaks is observed for mullite membrane electrode(64 mV from scan 1 to 5).The stability measurements are noted by changing the scan rate between 50 and 150 mV s−1.Furthermore,the results show that the Ni/Ni(OH)2 reference electrode covered with a mullite membrane is stable and reusable at 300℃temperature without any deterioration.The stability and reusability of prepared nickel reference electrode covered by mullite tube in the eutectic molten hydroxide were up to 9 days to carry out an electrochemical investigation,while for alumina tube reference electrode the stability and reliability were up to 3 days.The internal electrolytic material and ionic conductance can play an important role for future studies with this reference electrode along with optimisation of temperature and scan rate parameters.展开更多
The understanding of ozonation in bubble columns is the first step to describe this process for organic and inorganic pollutants in water medium in this equipment.This paper developed mathematical models for decomposi...The understanding of ozonation in bubble columns is the first step to describe this process for organic and inorganic pollutants in water medium in this equipment.This paper developed mathematical models for decomposition of ozone in liquid phase,with analytical solution for zero,first and second-orders kinetics for different pH values,with and without gaseous phase mass transfer effect in the ozone transfer to the liquid phase.The results models are satisfactory when compared with experimental data,and indicate the importance to consider such effects.展开更多
Solar-driven carbon dioxide(CO_(2))conversion including photocatalytic(PC),photoelectrochemical(PEC),photovoltaic plus electrochemical(PV/EC)systems,offers a renewable and scalable way to produce fuels and high-value ...Solar-driven carbon dioxide(CO_(2))conversion including photocatalytic(PC),photoelectrochemical(PEC),photovoltaic plus electrochemical(PV/EC)systems,offers a renewable and scalable way to produce fuels and high-value chemicals for environment and energy sustainability.This review summarizes the basic fundament and the recent advances in the field of solar-driven CO_(2)conversion.Expanding the visible-light absorption is an important strategy to improve solar energy conversion efficiency.The separation and migration of photogenerated charges carriers to surface sites and the surface catalytic processes also determine the photocatalytic performance.Surface engineering including co-catalyst loading,defect engineering,morphology control,surface modification,surface phase junction,and Z-scheme photocatalytic system construction,have become fundamental strategies to obtain high-efficiency photocatalysts.Similar to photocatalysis,these strategies have been applied to improve the conversion efficiency and Faradaic efficiency of typical PEC systems.In PV/EC systems,the electrode surface structure and morphology,electrolyte effects,and mass transport conditions affect the activity and selectivity of electrochemical CO_(2)reduction.Finally,the challenges and prospects are addressed for the development of solar-driven CO_(2)conversion system with high energy conversion efficiency,high product selectivity and stability.展开更多
The present study was carried out to evaluate the effect of different rates of dried cassava leafs in diet as replacement of protein sources on the weight gain and carcass yield of guinea-pigs, as well as on the physi...The present study was carried out to evaluate the effect of different rates of dried cassava leafs in diet as replacement of protein sources on the weight gain and carcass yield of guinea-pigs, as well as on the physico-chemical and technological properties of guinea-pigs’ meat. A total of forty-eight (48) eight-week-old guinea-pigs were divided in a completely randomized experimental design, in four groups and fed with the experimental foods. These experimental foods were formulated as follows: cassava-leaf (Manihot esculenta) powder was incorporated at concentrations of 0%, 8%, 10% and 12% respectively in replacement of protein sources for R0, R1, R2 and R3. Each treatment consisted of a group of 12 guinea pigs per paddock (6 males and 6 females). The initial weight (IW), final weight (FW), daily weight gain (DWG) and total gain (TG) were evaluated. At the 22nd week, animals of each group were sacrificed by bleeding, then skinned and eviscerated. Carcasses were cut, and some parts (loin, thigh and shoulder) were collected, deboned and analysed. The highest FW and carcass yield (CY) were obtained with the use of 10% cassava leafs (R2): 556 g (FW), 42.65% (CY) for males and 529.17 g (FW), 37.39% (CY) for females. The incorporation of 8% (R1) and 12% (R3) cassava leafs led to a significant increase (P < 0.05) in protein levels in the loins (22.89%) and shoulders (22.43%) of females and the thighs (21.68%) and shoulders (21.09%) of males. However, protein levels of male fed with R3 in the various parts studied were higher than females fed with the same diet. The study of the technological parameters of guinea-pig’s meat showed that the incorporation of 8% and 12% cassava leafs in the diet resulted in a significant decrease in the water holding capacity and technological yield in the different parts studied. These results show that, the incorporation of cassava leafs in guinea-pigs’ diet made it possible to obtain good growth (R2) and meat of good technological quality.展开更多
Proposed a novel approach to detect changes in the product quality of process systems by using negative selection algorithms inspired by the natural immune system. The most important input variables of the process sys...Proposed a novel approach to detect changes in the product quality of process systems by using negative selection algorithms inspired by the natural immune system. The most important input variables of the process system was represented by artificial immune cells, from which product quality was inferred, instead of directly using the prod- uct quality which was hard to measure online, e.g. the ash content of coal flotation con- centrate. The experiment was presented and then the result was analyzed.展开更多
The effect of essential oils from Syzygium aromaticum and Cymbopogon citratus on the lipid oxidation and microbial growth in beef patties was investigated in the present study. Essential oils were incorporated into th...The effect of essential oils from Syzygium aromaticum and Cymbopogon citratus on the lipid oxidation and microbial growth in beef patties was investigated in the present study. Essential oils were incorporated into the beef patties at 0.1% and 0.2% (w/w). The beef patties were then inoculated with cultures of E. coli and S. aureus and stored at 4°C. The control patties were processed without essential oil but inoculated with E. coli or S. aureus. The proximate composition, lipid oxidation and microbial counts were carried out after 7, 14, 21 and 28 days. Results showed that the incorporation of essential oils in beef patties did not significantly (P S. aromaticum at 0.2% reduced the E. coli growth by 1.48 log CFU/g and that of S. aureus by 6.52 log CFU/g while the incorporation of C. citratus at 0.2% reduced the E. coli growth by 1.21 log CFU/g and that of S. aureus by 1.4 log CFU/g after 28 days of storage. The pH measurement during the storage period showed a slight drop during the first 7 days of storage and an increase during the last 21 days in all samples. The sensory test of the beef patties showed that the consumers accepted patties formulated with the two essential oils. But the one made with 0.1% essential oil of S. aromaticum was the most accepted. The analysis of the color of beef patties between 0 and 28 days of storage revealed that the incorporation of essential oils retarded the degradation of the color of patties. Results obtained in the present study indicate the possibility of exploiting Syzygium aromaticum and Cymbopogon citratus essential oils to protect beef patties against lipid oxidation and microbial growth.展开更多
文摘Collagenase was isolated from fish waste (a mixture of haddock, herring, ground fish and flounder) using a Tris-buffer system. The proteins in the crude extract were precipitated using ammonium sulfate (40% - 80%) and purified with gel-filtration chromatography using Sephadex G-100. The results showed that the collagenase enzyme was produced as a latent enzyme and was activated with bovine trypsin and potassium thiocyanate (KSCN). The enzyme activity was affected by pH and temperature. Optimal enzyme activities were found at 35?C and a pH of 7.5 when insoluble collagene type I was used as substrate and the liberated amino acids were measured in relation to L-leucine in the presence of ninhydrin. The enzyme activity was completely inhibited by the action of ethylenediaminetetraacetic acid (EDTA) suggesting that the collagenase enzyme isolated from the fish waste is a metalloproteinase enzyme requiring metal ions for enzyme activity. Dialysis against KSCN decreased the enzyme total activity and increased its specific activity. Sodium dodecyl sulphate polyacryla-mide gel electrophoresis (SDS-PAGE) indicated that the purified procollagenase enzyme have only one band at molecular weight of 50 kilodaltons (kDa). When the enzyme was cleaved with trypsin, it was found to consist of two subunits: a large unit with a molecular weight of 50 kDa and a small unit with a molecular weight of 10 kDa.
基金supported by the University Salah Boubnider-Constantine 3 (Algeria).
文摘This research aims to study the bio-adsorption process of two dyes,Cibacron Green H3G(CG-H3G)and Terasil Red(TR),in a single system and to bring them closer to the industrial textile discharge by a binary mixture of two dyes(TR+CG-H3G).The Cockle Shell(CS)was used as a natural bio-adsorbent.The characterizations of CS were investigated by Fourier transform infrared(FTIR),X-ray diffraction(XRD),scanning electron microscopy(SEM),energy-dispersive X-ray spectroscopy(EDX)and Brunauer–Emmett–Teller(BET).The adsorption potential of Cockle Shells was tested in two cases(single and binary system)and determined by:contact time(0–60 min),bio-adsorption dose(3–15 g/L),initial concentration(10–300 mg/L),temperature(22–61°C)and pH solution(2–12).The study of bio-adsorption(equilibrium and kinetics)was conducted at 22°C.The kinetic studies demon-strated that a pseudo-second-order adsorption mechanism had a good correlation coefficient(R2≥0.999).The Langmuir isotherm modeling provided a well-defined description of TR and CG-H3G bio-adsorption on cockle shells,exhibiting maximum capacities of 29.41 and 3.69 mg/g respectively at 22°C.The thermodynamic study shows that the reaction between the TR,CG-H3G dyes molecules and the bio-adsorbent is exothermic,spontaneous in the range of 22–31°C with the aleatory character decrease at the solid-liquid interface.The study of selectivity in single and binary systems has been performed under optimal operating conditions using the industrial textile rejection pH(pH=6.04).CG-H3G dye is found to have a higher selectivity than TR in single(0–60 min)and binary systems with a range of 6–45 min,as shown by the selectivity measurement.It was discovered that CS has the capability to remove both CG-H3G and TR dyes in both simple and binary systems,making it a superior bio-adsorbent.
文摘The increase in oil prices and greenhouse gas emissions has led to the search for substitutes for fossil fuels. In Cameroon, the abundance of lignocellulosic resources is inherent to agricultural activity. Production of bioethanol remains a challenge given the crystallinity of cellulose and the presence of the complex. The pretreatment aimed to solubilize the lignin fraction and to make cellulose more accessible to the hydrolytic enzymes, was done using the organosolv process. A mathematical modeling was performed to point out the effect of the temperature on the kinetics of the release of the reducing sugars during the pretreatment. Two mathematical model was used, SAEMAN’s model and Response surface methodology. The first show that the kinetic parameters of the hydrolysis of the cellulose and reducing sugar are: 0.05089 min<sup>-1</sup>, 5358.1461 J·mol<sup>-1</sup>, 1383.03691 min<sup>-1</sup>, 51577.6100 J·mol<sup>-1</sup> respectively. The second model was used. Temperature is the factor having the most positive influence whereas, ethanol concentration is not an essential factor. To release the maximum, an organosolv pre-treatment of this sub-strate should be carried out at 209.08°C for 47.60 min with an ethanol-water ratio of 24.02%. Organosolv pre-treatment is an effective process for delignification of the lignocellulosic structure.
基金supported by the Inovation and Optimalization of Technologies for Natural Gas Dehydration(No.FR-TI1/173)
文摘This paper compares three methods for natural gas dehydration that are widely applied in industry：（1） absorption by triethylene glycol, （2） adsorption on solid desiccants and （3） condensation. A comparison is made according to their energy demand and suitability for use. The energy calculations are performed on a model where 105 Nm3/h water saturated natural gas is processed at 30 °C. The pressure of the gas varies from 7 to 20 MPa. The required outlet concentration of water in natural gas is equivalent to the dew point temperature of -10 °C at gas pressure of 4 MPa.
文摘It is necessary to understand all the prerequisites, which result in gas hydrate formation for safe design and control of a variety of processes in petroleum industry. Thermodynamic hydrate inhibitors (THIs) are normally used to preclude gas hydrate formation by shifting hydrate stability region to lower temperatures and higher pressures. Sometimes, it is difficult to avoid hydrate formation and hydrates will form anyway. In this situation, kinetic hydrate inhibitors (KHIs) can be used to postpone formation of gas hydrates by retarding hydrate nucleation and growth rate. In this study, two kinetic parameters including natural gas hydrate formation induction time and the rate of gas consumption were experimentally investigated in the presence of monoethylene glycol (MEG), L-tyrosine, and polyvinylpyrrolidone (PVP) at various concentrations in aqueous solutions. Since hydrate formation is a stochastic phenomenon, the repeatability of each kinetic parameter was evaluated several times and the average values for the hydrate formation induction times and the rates of gas consumption are reported. The results indicate that from the view point of hydrate formation induction time, 2 wt% PVP and 20 wt% MEG aqueous solutions have the highest values and are the best choices. It is also interpreted from the results that from the view point of the rate of gas consumption, 20 wt% MEG aqueous solution yields the lowest value and is the best choice. Finally, it is concluded that the combination of PVP and MEG in an aqueous solution has a simultaneous synergistic impact on natural gas hydrate formation induction time and the rate of gas consumption. Furthermore, a semi-empirical model based on chemical kinetic theory is applied to evaluate the hydrate formation induction time data. A good agreement between the experimental and calculated hydrate formation induction time data is observed.
文摘Jadomycin is an antibiotic that has shown activities against bacteria, yeasts and fungi as well as cytotoxic properties to cancer cells. Because of the wide range of its inhibitory actions, jadomycin shows promise as a novel antibiotic and cancer treatment drug. Streptomyces venezuelae are aerobic bacteria that produce jadomycin and the size of bacterial population can significantly affect the yield of jadomycin. Therefore, the bacterial population must be accurately measured in order to standardize the reproducibility of jadomycin production process. In this study, a dehydrogenase activity measurement test, using triphenyl tetrazolium chloride (TTC), was used to measure the dehydrogenase activity of Streptomyces venezuelae during growth in maltose-yeast extract-malt extract (MYM) broth. The aims were to evaluate the effectiveness of the test for measuring microbial growth and to study the effects of the test conditions (incubation time, incubation temperature and medium pH) on triphenyl formazan (TF) yield. The results showed that the TF yield was highly correlated to the optical density. The highest TF yield was observed at a pH of 6 at all incubation times and temperature. Lower TF yields were obtained at higher temperature (40 and 50oC) compared to those obtained at lower temperatures (22 and 30oC). The difference between the yields obtained at 22oC and 30oC were not significant. The differences between incubation time were also not significant. The recommended test conditions are an incubation time of 1 hour at a temperature of 30oC and a pH of 6 followed by three extractions using methanol.
文摘Indentation and reciprocating wear tests are carried out to study dent and wear resistance of superelastic Ti-Ni alloys. The effect of loading rate on the superelastic behavior of TiNi under indentation loading is investigated and compared to a new generation of shape memory alloys, i.e., 60NiTi. Only limited amount of work has been done to investigate the dependency of superelasticity on loading rate of TiNi under localized compressive loads, but much work is directed towards understanding the effect of strain rate on tensile properties. Understanding the superelastic behavior helps to employ superelastic alloys in applications where high impact loading is expected as in bearings and gears. In the present study, it is found that dent resistance of Ti-Ni alloy is not significantly affected by loading rate (within the employed loading conditions). It has also been found that new-generation 60NiTi alloy exhibits superior wear and dent resistance, as well as higher hardness compared to equiatomic TiNi.
基金Project supported by Postdoctoral Fellowship of South Africa
文摘The effects of aeration rate and impeller speed on the concentrate sulfur grade and recovery for batch flotation of a complex sulphide ore were investigated. The relationships between the water recovery and solid entrainment were discussed. It is found that the solid entrainment is linearly related to the water recovery regardless of aeration rate and impeller speed, and the higher sulfur recovery at the aeration rate of 2 and 4 L/min for the impeller speed of 1 500 r/min is considered to be the contribution of true flotation. Finally, the sulfur recovery flux is correlated with the bubble surface area flux based on the froth image at the different aeration rates and impeller speeds.
文摘The froth features in the batch flotation of a sulphide ore were investigated by using the digital image parameters of the froth, the small number emphasis(Nsne), the average grey level(Dagl) and the instability number(Nins), under different conditions of impeller speeds and aeration rates. It is found that the value of Nsne is strongly dependent on the average bubble size of the froth and Dagl on the volume fraction of solid in the froth, and the froth features during the batch flotation are influenced by impeller speed and aeration rate. A kinetic model of the concentrate solid flux was developed which relates the flotation process to the image parameters, Nsne and Dagl of the froth and predictions are well consistent with the experimental data.
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.
基金the financial support provided by“Plan Propio” of the University of Granada(Spain)by mean a “Researching Grant for Master’s Students”the financial support provided by the Ministry of Education(Spain)through Research Grant FPU16/00223
文摘In this work, the effect of the presence of nickel and lead in thermal decomposition of olive tree pruning (OTP), OTP-char and OTP-ashes was studied by thermogravimetry. Experiments were conducted in two kinds of atmosphere (nitrogen atmosphere and oxidizing atmosphere with 20% of O2) at a heating rate of 10 ℃/min. This investigation describes the chemical, physical and fuel properties of the OTP, which shows a similar composition to other lignocellulosic materials such as hazelnut husk and wood sawdust. In addition, SEM analysis indicated that OTP-char surface is higher than OTP surface with plenty of holes and channels. It makes the char an ideal support for metal retention specially for Pb metal (OTP retained 8.55 mg/g whereas OTP char retained 11.57 mg/g). On the other hand, metal retention occurred by adsorption or ion exchange, according to the IR spectrum of the samples. The results of thermogravimetric tests proved that the presence of lead did not have a strong effect on the decomposition of the samples, since TG and DTG curves were very similar. However, nickel increased the mass loss rate, accelerating the decomposition process, showing higher peaks in DTG curves. Additionally, for temperatures higher than 360 ℃, the volatilization of the samples was improved in the nickel-polluted sample, achieving a higher mass loss, getting more energy from the biomass and reducing the quantity of residues left after the process.
基金framework of grant:“Eco-friendly technologies for the management of seaweed biomass for products useful for sustainable agriculture and biosorbents used for the removal of heavy metal ions from the environment”(2019/33/B/NZ9/01844)from the National Science Centre in Poland.
文摘In this work,the properties of biochar produced from green macroalga Ulva intestinalis by pyrolysis were studied at temperatures of 300,500,and 700°C.This biochar was characterized in terms of multielemental composition,BET surface area,total pore volume,and biosorption properties toward phosphate ions.Biochar produced at 700°C-25 m2/g had the highest surface area.The kinetics and isotherms of sorption processes of phosphate ions as sorbate by these sorbents were investigated.Modified biochar was able to remove 84.3%of phosphate ions from wastewater,whereas non-modified biochar-only 40.6%.Hence,biochar enriched with phosphate ions can serve as a valuable soil amendment.Pot experiments performed on winter wheat(Triticum aestivum)with a 3%addition of dry Ulva intestinalis,pristine biochar,and Mg-modified biochar enriched with phosphate ions showed that these amendments stimulated plant growth(length and fresh weight of plants)as well as enlarging the chlorophyll content in leaves.Our results indicate that the production of biochar(pristine and Mg-impregnated)is a sustainable option to valorize the biomass of seaweeds,and to recycle phosphorus from wastewater.
文摘The sugarcane bagasse fuel is an energetic deposit opportunity for thermal and electricity generation in sugar society.Combustion behaviors,essential for effective operation of these devices are a necessity.A 3D numerical model has been developed in the commercial software Ansys Fluent.According to the fuel density and particle variable,this model took into account both suspension and grate model combustion.The realizable k-ε turbulent model with the P-1 model shows its advantage of describing such king problems and has been applied on the numerical model.The contour of the temperature,spices and the particle trajectory provided a clear understanding of bagasse fuel combustion in the furnace as well,bagasse particle goes through from initial heating to char combustion and its conversion to ash.The results obtained were in accordance with those of the literature.These results could be used to analyze this inexpensive combustion process for looking for the effect of design parameter change on the furnace performance.
文摘The reactivity between charged Li(Li_(0.115)Mn_(0.529)Ni_(0.339)Al_(0.017))O_(2)(Li-rich),single crystal Li(Ni_(0.8)Mn_(0.1)Co_(0.1))O_(2)(SC-NMC811),LiFePO_(4)(LFP) and LiMn_(0.8)Fe_(0.2)PO_(4)(LMFP) positive electrodes at different states of charge(SOCs) and traditional carbonate-based electrolyte at elevated temperatures is systematically studied using accelerating rate calorimetry(ARC).The results show that the SOC greatly affects the thermal stability of the Li-rich and SC-NMC811 when traditional carbonate-based electrolyte is used.Although an increase in the SOC increases the energy density of lithium-ion cells,it also increases the reactivity between charged Li-rich and SC-NMC811 samples with electrolyte at elevated temperatures.In comparison with SC-NMC811,the Li-rich samples are much more stable at elevated temperatures,and the latter have higher specific capacity.SC-NMC811 samples are less reactive than traditional polycrystalline NMC811.Both LFP and LMFP samples show excellent thermal stability at elevated temperatures.The substitution of Fe by Mn in the olivine series positive materials does not impact the reactivity with electrolyte.
文摘Fabrication of stable,reproducible and reusable reference electrodes for low energy and high-temperature steam splitting is of great interest for hydrogen fuel production without anthropogenic carbon dioxide(CO2)emission.This study has been conducted for the detection of suitable material for the fabrication of novel reference electrode.In the present scenario,this research is designed to fabricate a novel nickel reference electrode by using operating conditions of eutectic molten hydroxide(NaOH-KOH,49-51 mol%)at temperature 300℃in an ion-conducting membrane of alumina and mullite tube.Afterwards,the designed nickel reference electrode has been examined for its reusability and stability by using electrochemical technique and cyclic voltammetry.Five scans of cyclic voltammetry are performed for both membrane fabricated reference electrode.A slight positive shift in oxidation peaks is observed for mullite membrane electrode(64 mV from scan 1 to 5).The stability measurements are noted by changing the scan rate between 50 and 150 mV s−1.Furthermore,the results show that the Ni/Ni(OH)2 reference electrode covered with a mullite membrane is stable and reusable at 300℃temperature without any deterioration.The stability and reusability of prepared nickel reference electrode covered by mullite tube in the eutectic molten hydroxide were up to 9 days to carry out an electrochemical investigation,while for alumina tube reference electrode the stability and reliability were up to 3 days.The internal electrolytic material and ionic conductance can play an important role for future studies with this reference electrode along with optimisation of temperature and scan rate parameters.
文摘The understanding of ozonation in bubble columns is the first step to describe this process for organic and inorganic pollutants in water medium in this equipment.This paper developed mathematical models for decomposition of ozone in liquid phase,with analytical solution for zero,first and second-orders kinetics for different pH values,with and without gaseous phase mass transfer effect in the ozone transfer to the liquid phase.The results models are satisfactory when compared with experimental data,and indicate the importance to consider such effects.
基金supported by the National Natural Science Foundation of Chinathe Pioneer Initiative Action Project of the Chinese Academy of Sciences。
文摘Solar-driven carbon dioxide(CO_(2))conversion including photocatalytic(PC),photoelectrochemical(PEC),photovoltaic plus electrochemical(PV/EC)systems,offers a renewable and scalable way to produce fuels and high-value chemicals for environment and energy sustainability.This review summarizes the basic fundament and the recent advances in the field of solar-driven CO_(2)conversion.Expanding the visible-light absorption is an important strategy to improve solar energy conversion efficiency.The separation and migration of photogenerated charges carriers to surface sites and the surface catalytic processes also determine the photocatalytic performance.Surface engineering including co-catalyst loading,defect engineering,morphology control,surface modification,surface phase junction,and Z-scheme photocatalytic system construction,have become fundamental strategies to obtain high-efficiency photocatalysts.Similar to photocatalysis,these strategies have been applied to improve the conversion efficiency and Faradaic efficiency of typical PEC systems.In PV/EC systems,the electrode surface structure and morphology,electrolyte effects,and mass transport conditions affect the activity and selectivity of electrochemical CO_(2)reduction.Finally,the challenges and prospects are addressed for the development of solar-driven CO_(2)conversion system with high energy conversion efficiency,high product selectivity and stability.
文摘The present study was carried out to evaluate the effect of different rates of dried cassava leafs in diet as replacement of protein sources on the weight gain and carcass yield of guinea-pigs, as well as on the physico-chemical and technological properties of guinea-pigs’ meat. A total of forty-eight (48) eight-week-old guinea-pigs were divided in a completely randomized experimental design, in four groups and fed with the experimental foods. These experimental foods were formulated as follows: cassava-leaf (Manihot esculenta) powder was incorporated at concentrations of 0%, 8%, 10% and 12% respectively in replacement of protein sources for R0, R1, R2 and R3. Each treatment consisted of a group of 12 guinea pigs per paddock (6 males and 6 females). The initial weight (IW), final weight (FW), daily weight gain (DWG) and total gain (TG) were evaluated. At the 22nd week, animals of each group were sacrificed by bleeding, then skinned and eviscerated. Carcasses were cut, and some parts (loin, thigh and shoulder) were collected, deboned and analysed. The highest FW and carcass yield (CY) were obtained with the use of 10% cassava leafs (R2): 556 g (FW), 42.65% (CY) for males and 529.17 g (FW), 37.39% (CY) for females. The incorporation of 8% (R1) and 12% (R3) cassava leafs led to a significant increase (P < 0.05) in protein levels in the loins (22.89%) and shoulders (22.43%) of females and the thighs (21.68%) and shoulders (21.09%) of males. However, protein levels of male fed with R3 in the various parts studied were higher than females fed with the same diet. The study of the technological parameters of guinea-pig’s meat showed that the incorporation of 8% and 12% cassava leafs in the diet resulted in a significant decrease in the water holding capacity and technological yield in the different parts studied. These results show that, the incorporation of cassava leafs in guinea-pigs’ diet made it possible to obtain good growth (R2) and meat of good technological quality.
文摘Proposed a novel approach to detect changes in the product quality of process systems by using negative selection algorithms inspired by the natural immune system. The most important input variables of the process system was represented by artificial immune cells, from which product quality was inferred, instead of directly using the prod- uct quality which was hard to measure online, e.g. the ash content of coal flotation con- centrate. The experiment was presented and then the result was analyzed.
文摘The effect of essential oils from Syzygium aromaticum and Cymbopogon citratus on the lipid oxidation and microbial growth in beef patties was investigated in the present study. Essential oils were incorporated into the beef patties at 0.1% and 0.2% (w/w). The beef patties were then inoculated with cultures of E. coli and S. aureus and stored at 4°C. The control patties were processed without essential oil but inoculated with E. coli or S. aureus. The proximate composition, lipid oxidation and microbial counts were carried out after 7, 14, 21 and 28 days. Results showed that the incorporation of essential oils in beef patties did not significantly (P S. aromaticum at 0.2% reduced the E. coli growth by 1.48 log CFU/g and that of S. aureus by 6.52 log CFU/g while the incorporation of C. citratus at 0.2% reduced the E. coli growth by 1.21 log CFU/g and that of S. aureus by 1.4 log CFU/g after 28 days of storage. The pH measurement during the storage period showed a slight drop during the first 7 days of storage and an increase during the last 21 days in all samples. The sensory test of the beef patties showed that the consumers accepted patties formulated with the two essential oils. But the one made with 0.1% essential oil of S. aromaticum was the most accepted. The analysis of the color of beef patties between 0 and 28 days of storage revealed that the incorporation of essential oils retarded the degradation of the color of patties. Results obtained in the present study indicate the possibility of exploiting Syzygium aromaticum and Cymbopogon citratus essential oils to protect beef patties against lipid oxidation and microbial growth.
