When was the earliest glass produced in China? This has still been a question so far. Some archaeologists have thought that Yu Guo beads are real glass, the earliest glass(1100-771 B. C. ) in China. However, more deta...When was the earliest glass produced in China? This has still been a question so far. Some archaeologists have thought that Yu Guo beads are real glass, the earliest glass(1100-771 B. C. ) in China. However, more details of scientific investigations in this paper show that Yu Guo beads are mainly made of clastic quartz (>95%) with a small amount of clay and sintered under the low temperature(500-600℃). It is not a glassy body, but a kind of polycrystal ornaments.展开更多
The study was conducted on the status of the quality of wastewater from the tailings dam of Central Africa Gold Limited in Bibiani, Ghana, to ascertain the level of contamination of the wastewater. The tailings dam st...The study was conducted on the status of the quality of wastewater from the tailings dam of Central Africa Gold Limited in Bibiani, Ghana, to ascertain the level of contamination of the wastewater. The tailings dam stores process effluent from the gold extraction plant. Wastewater samples taken from the tailings dam were analyzed for physico-chemical characteristics. Arsenic, iron and cyanide were identified as the major pollutants in the tailings dam wastewater with average concentrations of 4.5, 25.2 and 11.1 mg.L1, respectively. Arsenic, iron and free CN （cyanide） concentrations in the process effluent exceeded the Ghana EPA discharge limits of 0.2, 2 and 0.2 mg.Ll, respectively. High conductivity, total dissolved solids, sulphate and ammonium were found in the wastewater studied. The tailings dam serves as a natural reservoir that removes most of the total suspended solids and the turbidity, resulting in the improvement in the aesthetic appeal of the wastewater. Nonetheless, arsenic, iron and cyanide concentrations were still high and hence the wastewater cannot be discharged into the environment without prior treatment.展开更多
The main aim of this research is to evaluate the water quality of King Abdullah Canal (KAC) using the water quality index method (WQI). For this purpose, nine different sampling sites were used in the calculation of W...The main aim of this research is to evaluate the water quality of King Abdullah Canal (KAC) using the water quality index method (WQI). For this purpose, nine different sampling sites were used in the calculation of WQI during the period of January to December 2012. The samples were analyzed for various physico-chemical parameters such as pH, electrical conductivity, total suspended solids, ions of Sodium, Potassium, Calcium, Magnesium, Fluorite, Chloride, Sulfate, Bicarbonate, and Nitrate in different seasons (winter, spring, summer and autumn). The analyzed results (by WQI method) have been used to suggest models for predicting water quality. The relative weight assigned to each parameter has a range from 1 to 5, based on the important parameters for drinking purposes. The computed WQI for the nine samples has a range from 46.66 to 542.08. The analysis reveals that the water quality status of the study area is varying from excellent to good in the upper part of the canal and from poor to very poor in the lower part of the canal. Comparing with the World Health Organization (WHO) and Jordan Standard (JS), the results indicate that the lower part of the canal is polluted. Therefore, the water is not safe for domestic use and needs further treatment, especially in the lower part of the canal.展开更多
The natural Salmonella abortus equi endotoxin(lipopolysaccharide) preparation was fractionated with organic solvents into smooth (S-) and rough(R-) fractions to prepare their corresponding lipid A moieties. The lipid ...The natural Salmonella abortus equi endotoxin(lipopolysaccharide) preparation was fractionated with organic solvents into smooth (S-) and rough(R-) fractions to prepare their corresponding lipid A moieties. The lipid A obtained from S-fraction(S-lip A) wa展开更多
This article describes the physico-chemical characterization of the sulfated zirconia catalysts prepared from zirconyl chloride, acetic acid and ammonium persulfate system under structure-directing-free and calcined a...This article describes the physico-chemical characterization of the sulfated zirconia catalysts prepared from zirconyl chloride, acetic acid and ammonium persulfate system under structure-directing-free and calcined at 650°C. The catalysts were characterized via an array of characterization techniques such as surface acidity and texture measurements, X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-VIS), scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDXS), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), thermogravimetric measurement (TG) coupled with a quadrupole mass spectrometer (MS), inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and/or mass spectrometry (ICP-MS). It is clear from TG-MS, ICP-AES, and IR analyses that the precursor of the catalyst is a sulphur species-doped zirconium oxy-hydroxyl acetate complex. The presence of zirconium-bound sulfate groups results in the superacidity of the catalyst and hence high activity in n-hexane isomerization. It is shown from nitrogen adsorption and desorption, FESEM, and HRTEM measurements that the materials exhibit mesoporous and nanocrystalline structure.展开更多
This work falls within the general framework of the valorization of the clays of Ivory Coast in order to propose innovative solutions in the resolution of certain problems related to development such as the depollutio...This work falls within the general framework of the valorization of the clays of Ivory Coast in order to propose innovative solutions in the resolution of certain problems related to development such as the depollution of water. Its main objective is therefore to study the physico-chemical properties of two Dabou clays with a view to using them in chemical processes for the treatment of dyeing wastewater. The results of the chemical analysis and the ray diffraction showed that the DAB 1 and DAB 2 samples are clays of the kaolinitic type consisting mainly of kaolinite with 51.17% for DAB 1 against 65.81% for DAB 2 and quartz with respectively 41.76% and 25.8% for DAB 1 and DAB 2. They also contain relatively large amounts of goethite with 9.96% for DAB 1 and 12.8% for DAB 2. The specific surfaces measured in both samples are greater than 25 m<sup>2</sup>/g. All the results of the physico-chemical characterization, in particular the presence in significant quantity of clay minerals, the presence of iron compounds and the large specific surface area of both samples, allow the conclusion that they can be used in adsorption studies and in the heterogeneous Fenton process for water treatment.展开更多
Beverage industries are one of the most polluting industries producing huge amount of wastewater effluents. These industries have been recognized to cause pollution by discharging effluent into receiving environment e...Beverage industries are one of the most polluting industries producing huge amount of wastewater effluents. These industries have been recognized to cause pollution by discharging effluent into receiving environment especially to the nearby rivers. The aim of this study is to determine the status of waste water effluent discharge of beverage industry in Ethiopia. Samples were collected from 8 beverage industries’ wastewater effluent discharge end pipe and examined for different physico-Chemical parameters such as: COD, BOD5, TSS, ammonia, total nitrogen, PH and phosphate. The observed values were ranged between 9 - 397.5 mg/L for TSS, 0.185 - 69.7 mg/l for phosphate, 0.265 - 71 mg/l for ammonia, 226 - 1975 mg/l for COD, 15 - 576 mg/L for BOD, 4 - 86.6 mg/l for total nitrogen and 5.21 - 12.37 for PH. The finding of the study revealed that most of the beverage industries were extremely high amount of total suspended solids (TSS), BOD and COD effluent discharge were found above the Ethiopian beverage industry effluent discharge limit value. Half of the sampled beverage industries’ effluent discharge of PH, total nitrogen, ammonia and phosphate were found within the limit value while the rest of the industries are still discharging their effluent above the national standard limit value. The continuous discharge of effluents into rivers without any additional treatment raises the level of pollution and toxicity, which have significantly adverse impact on the aquatic environment.展开更多
The physico-chemical characteristics of ten permanently flowing rivers from Kahuzi Biega National Park (Democratic Republic of Congo) were examined in July 2007. Water samples were collected from ten sites between 180...The physico-chemical characteristics of ten permanently flowing rivers from Kahuzi Biega National Park (Democratic Republic of Congo) were examined in July 2007. Water samples were collected from ten sites between 1800 and 3200 m asl and analyzed for the following chemical parameters: biological oxygen demand, total and carbonate hardness, alkalinity, total phosphorus, nitrogen, nitrate, and ammonia. Discharge, current velocity, temperature, and oxygen saturation were analyzed on site. In general, the chemical parameters revealed relatively low concentrations compared to others rivers in the region. The rivers were cold (10℃ - 15℃), well oxygenated, had low conductivity (generally <100 μS/cm), and had pH values ranging between 5.5 and 7.6. Nitrogen and phosphorus were also low (0.086 - 0.25 μmol/L for phosphorus and 2.21 - 4.25 μmol/L for nitrogen) in all rivers. The main natural sources of nitrogen and other nutriaents are from rain and atmospheric deposition, organic matter decomposition, and fixation of molecular nitrogen from allochthonous inorganic material. In the forested rivers of Kahuzi-Biega National Park the terrestrial and riparian environments are the only sources of nitrogen and phosphorus to the river water.展开更多
The industrial chemistry of oils and fats is a mature technology, with decades of experience and refinement behind current practices, therefore some physico-chemical characteristics of eleven vegetable oils sunflower ...The industrial chemistry of oils and fats is a mature technology, with decades of experience and refinement behind current practices, therefore some physico-chemical characteristics of eleven vegetable oils sunflower oil （four different manufacturing companies）, olive oil （three different manufacturing companies）, corn oil, castor oil, coconut oil and canola oil in Iraqi Kurdistan region （Hawler city center） have been evaluated according to association of official analytical chemists （AOAC） （1995） official methods. The refractive index, viscosity, acid value, peroxide value, pH values, and values of specific gravity of the vegetable oil samples were measured at various different conditions. The results showed that some of the oil samples have unacceptable values in comparison with the standards.展开更多
The characterization of clay raw materials of three clay deposits from Northern Cameroon was investigated. The three deposits, located in Gaschiga, Sekandé and Boulgou, are locally used as building materials, but...The characterization of clay raw materials of three clay deposits from Northern Cameroon was investigated. The three deposits, located in Gaschiga, Sekandé and Boulgou, are locally used as building materials, but no data are available on these materials and they are relatively unknown. Mineralogical, geochemical and physico-chemical characteristics were studied, using X-ray diffraction, X-ray fluorescence and physico-chemical analyses. Mineralogically, quartz was the most abundant mineral in the studied raw materials. It is associated to abundant quantity of smectite, kaolinite and K-feldspars, and slightly abundant to traces of hematite and amphibole. Geochemically, those clayey soils are more siliceous (SiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">, 51% - 59%) with significant amount of aluminum (Al</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">, 15% - 19%) followed by iron oxides (Fe</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">, 3% - 10%). Other oxides (K</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O, MgO, TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">, Na</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O, MnO, CaO and P</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">5</span></sub><span style="font-family:Verdana;">) are in relatively lower proportion. High level of silica content explains the sandy nature of these clays. The results of granulometric analysis show that the studied raw material contain sand (39% - 68%) as major grain size followed by clay particles (17% - 38%), silt (1% - 36%) and gravels (0% - 16%). The studied clayey soils were moderately plastic, with plasticity index values ranging from 13% to 30%, and are also characterized by very high liquidity limits of 34% - 63%.展开更多
The coastal sedimentary basin in southern Benin consists of monoclinal layers divided into two plateau zones (North and South) which are separated by a longitudinal depression ESE-WNW. The valleys of the main N-S-orie...The coastal sedimentary basin in southern Benin consists of monoclinal layers divided into two plateau zones (North and South) which are separated by a longitudinal depression ESE-WNW. The valleys of the main N-S-oriented rivers (Ouémé, Couffo and Mono) set the bondaries of the different plateau of the BSC (Coastal Sedimentary Basin). The present study, based on geology, hydrochemistry, temperature and log data available on boreholes, makes a physico-chemical characterization of the waters of the gushing aquifers of the coastal sedimentary basin of Benin. The gushing water boreholes are shared between the valleys of the main rivers of the BSC. Some of these boreholes are </span><span style="font-family:Verdana;">thermal with a water temperature between 38 and 69 degrees Celsius. The</span><span style="font-family:Verdana;"> hydrogeological correlations established in the BSC in accordance to the North-</span></span></span><span><span><span style="font-family:""> </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">South direction in the valleys of the main streams (Couffo and Ouémé) reveal that the captured aquifers are sands, marls and limestones that respond either </span><span style="font-family:Verdana;">in major discordance (northern zone) or above the sedimentation gaps</span><span style="font-family:Verdana;"> (southern zone). Chemical analyses have shown that gushing thermal waters are mineralized in the south with a neutral to basic pH and are highly concentrated with bicarbonate, calcium and magnesium ions. In the North, on the other hand, thermal waters are acidic with a pH ranging from 4.8 to 5.9. The acidic nature of the northern waters is influenced by the crystalline base while the southern neutral to basic waters are influenced by the lithological nature (limestone and marl) of the aquifer. The random distribution of thermal water boreholes in the valleys of the main BSC streams is believed to be related to tectonic events.展开更多
Honey harvesting throughout beekeeping is a technology recently introduced in Gabon comparing to the other African countries well known in international honey trade. The purpose of this study is to contribute to the k...Honey harvesting throughout beekeeping is a technology recently introduced in Gabon comparing to the other African countries well known in international honey trade. The purpose of this study is to contribute to the knowledge of the quality of multi-flower honeys from the savannah-gallery forest complex and primary forest not well documented in Gabon. Physical and chemical parameters of different honeys were analyzed using the official methods of analysis of the Association of Official Analytical Chemists. The results of physico-chemical analysis show variations in pH (3.4 to 3.9), free acidity (37.12 to 76.65 meq∙kg−1), water content (17.49% to 21.21%), electrical conductivity (0.64 to 1.24 mS∙cm−1), density (1.02 to 1.03) and total sugar content (77% to 82%). These variations were significantly different (p < 0.05) between certain honeys, but independent of the type of ecosystem considered. The pH values confirmed the botanical origin of the five honeys. The physico-chemical parameters of the honeys show significant correlations (p < 0.05). Moisture content is negatively correlated with conductivity (r = −0.628), pH (r = −0.631), density (r = −0.552) and total sugar content (r = −0.890). Conductivity is positively correlated with free acidity (r = 0.688) and total sugar content (r = 0.776), and negatively correlated with water content (r = −0.628). All honeys were in line with Codex Alimentarius standards, except for 3 types of honey (M1, M2 and M4) for free acidity and electrical conductivity, showing possible fermentation of these honeys.展开更多
The study is focused on the post impact of oil spill contamination of groundwater in Bassambiri Nembe Bayelsa State. Groundwater samples were sampled from hand dug wells from eight stations including the control point...The study is focused on the post impact of oil spill contamination of groundwater in Bassambiri Nembe Bayelsa State. Groundwater samples were sampled from hand dug wells from eight stations including the control point for physico-chemical investigation using sterilized glass bottles. Standard methods were used for the analyses. The result of physico-chemical parameters analyzed shows that the values of the groundwater pH ranged between 5.90 - 6.35, electrical conductivity between 80.39 - 89.23 μS/cm, Salinity 23.3 - 28.69 mg/l, Turbidity 1.71 - 3.84 NTU, Biochemical Oxygen Demand (BOD) 1.12 - 1.36 mg/l, Alkalinity 8.56 - 12.12 mg/l, Total Hardness 11.8 - 14.47 mg/l and Temperature 26.1℃ - 27.3℃. Analysis of cations shows that Na ranged from 7.38 - 10.34 mg/l, K 0.26 - 0.49 mg/l, Calcium ion levels 2.56 - 3.59 mg/l and Mg 0.88 mg/l - 1.23 mg/l. The anions showed Potassium ion levels ranged from 0.01 mg/l - 0.02 mg/l, Chloride ion levels 12.29 mg/l - 15.88 mg/l, Fluoride ion levels 0.01 mg/l and Nitrates from 0.27 mg/l - 0.48 mg/l. Total Heterotopic Fungi population ranged from 15.26 - 48.55 Coliform Forming units/ml. The maximum permissible value of total coliforms in drinking water was exceeded. However, the Total Hydrocarbon Concentration (THC) across the groundwater sample points was less than 0.01 mg/l. The concentration of PAH and BTEX was 0.01 mg/l across the study area. The heavy metal concentrations in the groundwater samples were negligible with levels of 0.01 mg/l observed in the study area except for iron ranging from 0.20 - 0.56 mg/l levels above the WHO permissible limit. The physico-chemical parameters of groundwater indicate that they fall below WHO permissible limits. The cations and anions concentration indicate a stable and healthy water system which is relatively good. The groundwater system has high levels of iron in groundwater and bacterial contamination. Treatment is required to avoid acute and chronic iron overload resulting from consumption from drinking groundwater within the study area.展开更多
Geopolymers are an alternative to Portland cement, well known for their contribution to greenhouse gas emissions. Finding materials that can validly replace Portland cement is a challenge. It is in this logic that thi...Geopolymers are an alternative to Portland cement, well known for their contribution to greenhouse gas emissions. Finding materials that can validly replace Portland cement is a challenge. It is in this logic that this work was undertaken with the objective of characterizing two local clay resources of Togo as raw materials for geopolymers. The physico-chemical properties of these clays were determined by characterization using X-ray diffraction (XRD), Fourier transform infrared (FTIR), thermogravimetric (TGA) and elemental analysis (ICP-OES). The results show that these clays contain kaolinite and therefore can be used in the formulation of geopolymers. The characterized clays underwent heat treatments transforming the crystalline phases into more reactive amorphous phases and then were activated by an alkaline solution in order to formulate the geopolymer materials. These elaborated materials were analyzed by Fourier transform infrared to identify the types of bonds formed. The results of these analyses show that these two local clays are well suited to be used in synthesizing geopolymers. Our future work will focus on the constraints of consolidation as well as the mechanical properties of these geopolymer materials.展开更多
In this research work, fiber extracted from the bark of <i>Cola</i> <i>lepidota</i> (<i>CL</i>) plant, grown in the flora of Southern part of Cameroon, was investigated for composit...In this research work, fiber extracted from the bark of <i>Cola</i> <i>lepidota</i> (<i>CL</i>) plant, grown in the flora of Southern part of Cameroon, was investigated for composites reinforcement. The investigation was carried via evaluation of <span>water absorption capacity, moisture content, real density, porosity, chemical composition, chemical structure and thermal behaviour. It was discovered that the new fiber has relatively low moisture content and water absorption capacity similar to those of other investigated natural fibers such as flax, sisal, coconut, hemp and jute. Its porosity was found appropriate for composite production and the fiber was found to be thermally stable up to 230°C, with maximum degradation temperature of 325°C. The main constituents of the fibre include cellulose, hemicellulose and lignin. In conclusion, based on the properties investigated, this fiber is considered suitable for composite manufacture.展开更多
Ten most popular brands of commercial Turkish set-type yoghurts were collected from local retail outlets in Hatay, Turkey for two separate periods, and analyzed for basic nutrients, physico-chemical properties, volati...Ten most popular brands of commercial Turkish set-type yoghurts were collected from local retail outlets in Hatay, Turkey for two separate periods, and analyzed for basic nutrients, physico-chemical properties, volatile aroma compounds and free fatty acid profiles to compare their differences among the yoghurt products. The results showed that there were significant differences (P<0.05, 0.01, or 0.001) and variations in physico-chemical indices, volatile aroma compounds and volatile free fatty acid profiles among the yoghurt brands, which ultimately influence the flavor quality of the product. Acetaldehyde was predominant volatile compound in yoghurts, which followed by acetone, acetoin, diacetyl and ethanol. The level of diacetly was inversely related to titratable acidity, acetaldehyde and ethanoic acid. From ketones with high carbones 2-undecanone and 2-pentadecanone were higher than 2-butanone, 2-nanonane and 2-tridecanone. These ketones are related to fat content of yoghurt. Among short chain free fatty acids, ethanoic (acetic) acid was the most abundant in yoghurts, followed by hexanoic, octanoic and butanoic acids. These differences in detected chemical compositions of volatile compounds and free fatty acids would be applicable to predict flavor, nutritional value, quality control or shelf-life of the commmercial set-type Turkish yoghurts.展开更多
The spatial distribution of physico-chemical parameters（sea surface temperature（SST）, p H, sea surface salinity（SSS）, dissolved oxygen（DO） and Secchi depth） along with filterable nutrients（dissolved inorganic...The spatial distribution of physico-chemical parameters（sea surface temperature（SST）, p H, sea surface salinity（SSS）, dissolved oxygen（DO） and Secchi depth） along with filterable nutrients（dissolved inorganic nitrate（DIN）,dissolved inorganic phosphate（DIP） and reactive silicate（DSi）） are measured in the winter months of November,December, January and February for four consecutive years from 2009–2010 to 2012–2013 on the shallow continental shelf（〈20 m bathymetry） of the coastal waters（up to 18 km away from shoreline） of the northern Bay of Bengal（n Bo B） during the highest high tide（HHT） and lowest low tide（LLT） hours for the first time. The variability of the coastal biogeochemical environment is assessed during the HHT and LLT hours and for this purpose, seawater samples are collected from seven different locations of a transect in the coastal region. Physicochemical parameters（except SST） show significant difference in magnitude during the HHT and LLT hours respectively. p H, SSS and DO are found to increase in the HHT hours and vice-versa. The data reveal that during the LLT hours, a relative increase of freshwater input in the n Bo B can have elevated the nutrient concentration compared with that observed during the HHT hours. The ratio of nutrient concentration is found to deviate significantly from the Redfield ratio. The abundance of DIP is much higher compared with that of DIN and DSi.The anthropogenic sources of DIP from the upstream flow（especially the domestic effluent of several metropolises） can be mainly attributed behind such an observation. In order to characterize and establish the trend of such variation in such an important bio-climatic region, long-term and systematic ecosystem monitoring in the coastal water of the n Bo B northern Bay of Bengal should be carried out throughout the year.展开更多
To contribute to the valorization of local materials, the physico-chemical and mineralogical characterization of two clay materials MJ and MN collected in the Mayo Tsanaga river which crosses the Makabaye district of ...To contribute to the valorization of local materials, the physico-chemical and mineralogical characterization of two clay materials MJ and MN collected in the Mayo Tsanaga river which crosses the Makabaye district of Maroua (Cameroon) was carried out. For this purpose, various methods of characterization have been used, namely granulometric analysis, Atterberg limits, X-ray fluorescence spectrometry and X-ray diffraction. It is apparent from the granulometry that the clay materials studied titrate 33.77% of clays for MJ against 44.13% for MN. The plasticity indices Ip with values IpMJ = 19.27% and IpMN = 23.4% place the materials in the plastic domain and offer them the possibility to being shaped into objects. The chemical composition of the MJ and MN materials reveals that the silicon oxide SiO2, the aluminumoxide Al2O3 and iron oxide Fe2O3 are their main constituents. The X-ray diffraction of the MJ and MN materials shows that they consist mainly of quartz with associated kaolinite, illite, montmorillonite, perlialite, dickite, nacrite, amesite, albite, brookite and anorthite. In addition to these, 2/1 minerals such as muscovite, nontronite, glauconite, and phlogopite are also identified in the MJ material. The peaks of sanidine, microcline and gismondine are also found in the MN material. The materials being rich in clay minerals 2/1 can be valorized in the adsorption and the absorption of the oils and greases and in the waterproofing of the grounds. The presence of quartz, kaolinite and illite is undoubtedly favorable for the manufacture of ceramic products in terracotta. These products will be obtained at a relatively lower temperature due to illite, feldspars and iron minerals that provide vitrification during firing by forming eutectics. The aluminosilicate amorphous phases contained in the studied materials can be exploited to produce geopolymer cements and concretes.展开更多
Thirty-one duplicate and similar named rice germplasms of Bangladesh were studied to assess the genetic variation for the agro-morphological and physico-chemical traits and simple sequence repeat banding patterns duri...Thirty-one duplicate and similar named rice germplasms of Bangladesh were studied to assess the genetic variation for the agro-morphological and physico-chemical traits and simple sequence repeat banding patterns during 2009–2012 at Bangladesh Rice Research Institute. The range of variations within the cultivar groups showed higher degree. The principal component analysis showed that the first five components with vector values > 1 contributed 82.90% of the total variations. The cluster analysis grouped the genotypes into four clusters, where no duplicate germplasm was found. The highest number(11) of genotypes was constellated in cluster I and the lowest(3) in cluster II. The intra- and inter-cluster distances were the maximum in cluster I(0.93) and between clusters I and IV(24.61), respectively, and the minimum in cluster IV(0.62) and between clusters I and III(5.07), respectively. The cluster mean revealed that the crosses between the genotypes of cluster I with those of clusters II and IV would exhibit high heterosis for maximum good characters. A total of 350 alleles varied from 3(RM277) to 14(RM21) with an average of 7.8 per locus were detected at 45 microsatellite loci across the 31 rice accessions. The gene diversity ranged from 0.48 to 0.90 with an average of 0.77, and the polymorphism information content values from 0.44(RM133) to 0.89(RM206) with an average of 0.74. RM206, RM21, RM55, RM258 and RM433 were considered as the best markers on the basis of their higher polymorphism information content values. The dendrogram from unweighted pair-group method with arithmetic average clustering also classified the genotypes into four groups, where group IV comprised of 20 genotypes and group III of one genotype, but no duplicate was found. Finally, similar and duplicate named rice germplasms need to be conserved in gene bank as are distinct from each other.展开更多
The deterioration of water quality in lakes constitutes an environmental problem faced by humanity. The Nkolbisson artificial lake which is located downstream of the Abiergue and Mintotomo streams in Yaounde is under ...The deterioration of water quality in lakes constitutes an environmental problem faced by humanity. The Nkolbisson artificial lake which is located downstream of the Abiergue and Mintotomo streams in Yaounde is under the influence of various forms of pollution, mostly resulting from human activities. There is proliferation of algae on the lake surface that consumes the available oxygen in the lake. The main objective of the current study is to evaluate the different forms of pollutants in the lake, in order to propose efficient solutions for a suitable management strategy, basing on the physico-chemical and biological analysis. The lake retains an average of 2535.49 tons/year of suspended solids in the rainy season and 1438.05 tons/year in the dry season. The range of dissolved oxygen (5.2 - 3.8 mg/l);pH (7.8 - 6.8);temperature (23.9°C - 23.1°C);electrical conductivity (266.1 - 87.3 μS/cm);turbidity (22.3 - 10 UNT);suspended solid (240 - 40 mg/l);BOD (55 - 8 mg/l);COD (76 - 87.3 mg/l). Biologically, faecal coliforms fluctuates between (42 × 102 - 425 × 103 FCU/100 ml), faecal streptococci (8 × 103 - 158 × 103 FCU/100 ml) and total Coliform (15 × 103 - 78 × 106 FCU/100 ml) evidence that, the studied lake is highly polluted. Consequently the lake retains an average of 2888.7 tons/year of suspended matter.展开更多
文摘When was the earliest glass produced in China? This has still been a question so far. Some archaeologists have thought that Yu Guo beads are real glass, the earliest glass(1100-771 B. C. ) in China. However, more details of scientific investigations in this paper show that Yu Guo beads are mainly made of clastic quartz (>95%) with a small amount of clay and sintered under the low temperature(500-600℃). It is not a glassy body, but a kind of polycrystal ornaments.
文摘The study was conducted on the status of the quality of wastewater from the tailings dam of Central Africa Gold Limited in Bibiani, Ghana, to ascertain the level of contamination of the wastewater. The tailings dam stores process effluent from the gold extraction plant. Wastewater samples taken from the tailings dam were analyzed for physico-chemical characteristics. Arsenic, iron and cyanide were identified as the major pollutants in the tailings dam wastewater with average concentrations of 4.5, 25.2 and 11.1 mg.L1, respectively. Arsenic, iron and free CN （cyanide） concentrations in the process effluent exceeded the Ghana EPA discharge limits of 0.2, 2 and 0.2 mg.Ll, respectively. High conductivity, total dissolved solids, sulphate and ammonium were found in the wastewater studied. The tailings dam serves as a natural reservoir that removes most of the total suspended solids and the turbidity, resulting in the improvement in the aesthetic appeal of the wastewater. Nonetheless, arsenic, iron and cyanide concentrations were still high and hence the wastewater cannot be discharged into the environment without prior treatment.
文摘The main aim of this research is to evaluate the water quality of King Abdullah Canal (KAC) using the water quality index method (WQI). For this purpose, nine different sampling sites were used in the calculation of WQI during the period of January to December 2012. The samples were analyzed for various physico-chemical parameters such as pH, electrical conductivity, total suspended solids, ions of Sodium, Potassium, Calcium, Magnesium, Fluorite, Chloride, Sulfate, Bicarbonate, and Nitrate in different seasons (winter, spring, summer and autumn). The analyzed results (by WQI method) have been used to suggest models for predicting water quality. The relative weight assigned to each parameter has a range from 1 to 5, based on the important parameters for drinking purposes. The computed WQI for the nine samples has a range from 46.66 to 542.08. The analysis reveals that the water quality status of the study area is varying from excellent to good in the upper part of the canal and from poor to very poor in the lower part of the canal. Comparing with the World Health Organization (WHO) and Jordan Standard (JS), the results indicate that the lower part of the canal is polluted. Therefore, the water is not safe for domestic use and needs further treatment, especially in the lower part of the canal.
文摘The natural Salmonella abortus equi endotoxin(lipopolysaccharide) preparation was fractionated with organic solvents into smooth (S-) and rough(R-) fractions to prepare their corresponding lipid A moieties. The lipid A obtained from S-fraction(S-lip A) wa
文摘This article describes the physico-chemical characterization of the sulfated zirconia catalysts prepared from zirconyl chloride, acetic acid and ammonium persulfate system under structure-directing-free and calcined at 650°C. The catalysts were characterized via an array of characterization techniques such as surface acidity and texture measurements, X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-VIS), scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDXS), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), thermogravimetric measurement (TG) coupled with a quadrupole mass spectrometer (MS), inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and/or mass spectrometry (ICP-MS). It is clear from TG-MS, ICP-AES, and IR analyses that the precursor of the catalyst is a sulphur species-doped zirconium oxy-hydroxyl acetate complex. The presence of zirconium-bound sulfate groups results in the superacidity of the catalyst and hence high activity in n-hexane isomerization. It is shown from nitrogen adsorption and desorption, FESEM, and HRTEM measurements that the materials exhibit mesoporous and nanocrystalline structure.
文摘This work falls within the general framework of the valorization of the clays of Ivory Coast in order to propose innovative solutions in the resolution of certain problems related to development such as the depollution of water. Its main objective is therefore to study the physico-chemical properties of two Dabou clays with a view to using them in chemical processes for the treatment of dyeing wastewater. The results of the chemical analysis and the ray diffraction showed that the DAB 1 and DAB 2 samples are clays of the kaolinitic type consisting mainly of kaolinite with 51.17% for DAB 1 against 65.81% for DAB 2 and quartz with respectively 41.76% and 25.8% for DAB 1 and DAB 2. They also contain relatively large amounts of goethite with 9.96% for DAB 1 and 12.8% for DAB 2. The specific surfaces measured in both samples are greater than 25 m<sup>2</sup>/g. All the results of the physico-chemical characterization, in particular the presence in significant quantity of clay minerals, the presence of iron compounds and the large specific surface area of both samples, allow the conclusion that they can be used in adsorption studies and in the heterogeneous Fenton process for water treatment.
文摘Beverage industries are one of the most polluting industries producing huge amount of wastewater effluents. These industries have been recognized to cause pollution by discharging effluent into receiving environment especially to the nearby rivers. The aim of this study is to determine the status of waste water effluent discharge of beverage industry in Ethiopia. Samples were collected from 8 beverage industries’ wastewater effluent discharge end pipe and examined for different physico-Chemical parameters such as: COD, BOD5, TSS, ammonia, total nitrogen, PH and phosphate. The observed values were ranged between 9 - 397.5 mg/L for TSS, 0.185 - 69.7 mg/l for phosphate, 0.265 - 71 mg/l for ammonia, 226 - 1975 mg/l for COD, 15 - 576 mg/L for BOD, 4 - 86.6 mg/l for total nitrogen and 5.21 - 12.37 for PH. The finding of the study revealed that most of the beverage industries were extremely high amount of total suspended solids (TSS), BOD and COD effluent discharge were found above the Ethiopian beverage industry effluent discharge limit value. Half of the sampled beverage industries’ effluent discharge of PH, total nitrogen, ammonia and phosphate were found within the limit value while the rest of the industries are still discharging their effluent above the national standard limit value. The continuous discharge of effluents into rivers without any additional treatment raises the level of pollution and toxicity, which have significantly adverse impact on the aquatic environment.
文摘The physico-chemical characteristics of ten permanently flowing rivers from Kahuzi Biega National Park (Democratic Republic of Congo) were examined in July 2007. Water samples were collected from ten sites between 1800 and 3200 m asl and analyzed for the following chemical parameters: biological oxygen demand, total and carbonate hardness, alkalinity, total phosphorus, nitrogen, nitrate, and ammonia. Discharge, current velocity, temperature, and oxygen saturation were analyzed on site. In general, the chemical parameters revealed relatively low concentrations compared to others rivers in the region. The rivers were cold (10℃ - 15℃), well oxygenated, had low conductivity (generally <100 μS/cm), and had pH values ranging between 5.5 and 7.6. Nitrogen and phosphorus were also low (0.086 - 0.25 μmol/L for phosphorus and 2.21 - 4.25 μmol/L for nitrogen) in all rivers. The main natural sources of nitrogen and other nutriaents are from rain and atmospheric deposition, organic matter decomposition, and fixation of molecular nitrogen from allochthonous inorganic material. In the forested rivers of Kahuzi-Biega National Park the terrestrial and riparian environments are the only sources of nitrogen and phosphorus to the river water.
文摘The industrial chemistry of oils and fats is a mature technology, with decades of experience and refinement behind current practices, therefore some physico-chemical characteristics of eleven vegetable oils sunflower oil （four different manufacturing companies）, olive oil （three different manufacturing companies）, corn oil, castor oil, coconut oil and canola oil in Iraqi Kurdistan region （Hawler city center） have been evaluated according to association of official analytical chemists （AOAC） （1995） official methods. The refractive index, viscosity, acid value, peroxide value, pH values, and values of specific gravity of the vegetable oil samples were measured at various different conditions. The results showed that some of the oil samples have unacceptable values in comparison with the standards.
文摘The characterization of clay raw materials of three clay deposits from Northern Cameroon was investigated. The three deposits, located in Gaschiga, Sekandé and Boulgou, are locally used as building materials, but no data are available on these materials and they are relatively unknown. Mineralogical, geochemical and physico-chemical characteristics were studied, using X-ray diffraction, X-ray fluorescence and physico-chemical analyses. Mineralogically, quartz was the most abundant mineral in the studied raw materials. It is associated to abundant quantity of smectite, kaolinite and K-feldspars, and slightly abundant to traces of hematite and amphibole. Geochemically, those clayey soils are more siliceous (SiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">, 51% - 59%) with significant amount of aluminum (Al</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">, 15% - 19%) followed by iron oxides (Fe</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">, 3% - 10%). Other oxides (K</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O, MgO, TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">, Na</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O, MnO, CaO and P</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">5</span></sub><span style="font-family:Verdana;">) are in relatively lower proportion. High level of silica content explains the sandy nature of these clays. The results of granulometric analysis show that the studied raw material contain sand (39% - 68%) as major grain size followed by clay particles (17% - 38%), silt (1% - 36%) and gravels (0% - 16%). The studied clayey soils were moderately plastic, with plasticity index values ranging from 13% to 30%, and are also characterized by very high liquidity limits of 34% - 63%.
文摘The coastal sedimentary basin in southern Benin consists of monoclinal layers divided into two plateau zones (North and South) which are separated by a longitudinal depression ESE-WNW. The valleys of the main N-S-oriented rivers (Ouémé, Couffo and Mono) set the bondaries of the different plateau of the BSC (Coastal Sedimentary Basin). The present study, based on geology, hydrochemistry, temperature and log data available on boreholes, makes a physico-chemical characterization of the waters of the gushing aquifers of the coastal sedimentary basin of Benin. The gushing water boreholes are shared between the valleys of the main rivers of the BSC. Some of these boreholes are </span><span style="font-family:Verdana;">thermal with a water temperature between 38 and 69 degrees Celsius. The</span><span style="font-family:Verdana;"> hydrogeological correlations established in the BSC in accordance to the North-</span></span></span><span><span><span style="font-family:""> </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">South direction in the valleys of the main streams (Couffo and Ouémé) reveal that the captured aquifers are sands, marls and limestones that respond either </span><span style="font-family:Verdana;">in major discordance (northern zone) or above the sedimentation gaps</span><span style="font-family:Verdana;"> (southern zone). Chemical analyses have shown that gushing thermal waters are mineralized in the south with a neutral to basic pH and are highly concentrated with bicarbonate, calcium and magnesium ions. In the North, on the other hand, thermal waters are acidic with a pH ranging from 4.8 to 5.9. The acidic nature of the northern waters is influenced by the crystalline base while the southern neutral to basic waters are influenced by the lithological nature (limestone and marl) of the aquifer. The random distribution of thermal water boreholes in the valleys of the main BSC streams is believed to be related to tectonic events.
文摘Honey harvesting throughout beekeeping is a technology recently introduced in Gabon comparing to the other African countries well known in international honey trade. The purpose of this study is to contribute to the knowledge of the quality of multi-flower honeys from the savannah-gallery forest complex and primary forest not well documented in Gabon. Physical and chemical parameters of different honeys were analyzed using the official methods of analysis of the Association of Official Analytical Chemists. The results of physico-chemical analysis show variations in pH (3.4 to 3.9), free acidity (37.12 to 76.65 meq∙kg−1), water content (17.49% to 21.21%), electrical conductivity (0.64 to 1.24 mS∙cm−1), density (1.02 to 1.03) and total sugar content (77% to 82%). These variations were significantly different (p < 0.05) between certain honeys, but independent of the type of ecosystem considered. The pH values confirmed the botanical origin of the five honeys. The physico-chemical parameters of the honeys show significant correlations (p < 0.05). Moisture content is negatively correlated with conductivity (r = −0.628), pH (r = −0.631), density (r = −0.552) and total sugar content (r = −0.890). Conductivity is positively correlated with free acidity (r = 0.688) and total sugar content (r = 0.776), and negatively correlated with water content (r = −0.628). All honeys were in line with Codex Alimentarius standards, except for 3 types of honey (M1, M2 and M4) for free acidity and electrical conductivity, showing possible fermentation of these honeys.
文摘The study is focused on the post impact of oil spill contamination of groundwater in Bassambiri Nembe Bayelsa State. Groundwater samples were sampled from hand dug wells from eight stations including the control point for physico-chemical investigation using sterilized glass bottles. Standard methods were used for the analyses. The result of physico-chemical parameters analyzed shows that the values of the groundwater pH ranged between 5.90 - 6.35, electrical conductivity between 80.39 - 89.23 μS/cm, Salinity 23.3 - 28.69 mg/l, Turbidity 1.71 - 3.84 NTU, Biochemical Oxygen Demand (BOD) 1.12 - 1.36 mg/l, Alkalinity 8.56 - 12.12 mg/l, Total Hardness 11.8 - 14.47 mg/l and Temperature 26.1℃ - 27.3℃. Analysis of cations shows that Na ranged from 7.38 - 10.34 mg/l, K 0.26 - 0.49 mg/l, Calcium ion levels 2.56 - 3.59 mg/l and Mg 0.88 mg/l - 1.23 mg/l. The anions showed Potassium ion levels ranged from 0.01 mg/l - 0.02 mg/l, Chloride ion levels 12.29 mg/l - 15.88 mg/l, Fluoride ion levels 0.01 mg/l and Nitrates from 0.27 mg/l - 0.48 mg/l. Total Heterotopic Fungi population ranged from 15.26 - 48.55 Coliform Forming units/ml. The maximum permissible value of total coliforms in drinking water was exceeded. However, the Total Hydrocarbon Concentration (THC) across the groundwater sample points was less than 0.01 mg/l. The concentration of PAH and BTEX was 0.01 mg/l across the study area. The heavy metal concentrations in the groundwater samples were negligible with levels of 0.01 mg/l observed in the study area except for iron ranging from 0.20 - 0.56 mg/l levels above the WHO permissible limit. The physico-chemical parameters of groundwater indicate that they fall below WHO permissible limits. The cations and anions concentration indicate a stable and healthy water system which is relatively good. The groundwater system has high levels of iron in groundwater and bacterial contamination. Treatment is required to avoid acute and chronic iron overload resulting from consumption from drinking groundwater within the study area.
文摘Geopolymers are an alternative to Portland cement, well known for their contribution to greenhouse gas emissions. Finding materials that can validly replace Portland cement is a challenge. It is in this logic that this work was undertaken with the objective of characterizing two local clay resources of Togo as raw materials for geopolymers. The physico-chemical properties of these clays were determined by characterization using X-ray diffraction (XRD), Fourier transform infrared (FTIR), thermogravimetric (TGA) and elemental analysis (ICP-OES). The results show that these clays contain kaolinite and therefore can be used in the formulation of geopolymers. The characterized clays underwent heat treatments transforming the crystalline phases into more reactive amorphous phases and then were activated by an alkaline solution in order to formulate the geopolymer materials. These elaborated materials were analyzed by Fourier transform infrared to identify the types of bonds formed. The results of these analyses show that these two local clays are well suited to be used in synthesizing geopolymers. Our future work will focus on the constraints of consolidation as well as the mechanical properties of these geopolymer materials.
文摘In this research work, fiber extracted from the bark of <i>Cola</i> <i>lepidota</i> (<i>CL</i>) plant, grown in the flora of Southern part of Cameroon, was investigated for composites reinforcement. The investigation was carried via evaluation of <span>water absorption capacity, moisture content, real density, porosity, chemical composition, chemical structure and thermal behaviour. It was discovered that the new fiber has relatively low moisture content and water absorption capacity similar to those of other investigated natural fibers such as flax, sisal, coconut, hemp and jute. Its porosity was found appropriate for composite production and the fiber was found to be thermally stable up to 230°C, with maximum degradation temperature of 325°C. The main constituents of the fibre include cellulose, hemicellulose and lignin. In conclusion, based on the properties investigated, this fiber is considered suitable for composite manufacture.
文摘Ten most popular brands of commercial Turkish set-type yoghurts were collected from local retail outlets in Hatay, Turkey for two separate periods, and analyzed for basic nutrients, physico-chemical properties, volatile aroma compounds and free fatty acid profiles to compare their differences among the yoghurt products. The results showed that there were significant differences (P<0.05, 0.01, or 0.001) and variations in physico-chemical indices, volatile aroma compounds and volatile free fatty acid profiles among the yoghurt brands, which ultimately influence the flavor quality of the product. Acetaldehyde was predominant volatile compound in yoghurts, which followed by acetone, acetoin, diacetyl and ethanol. The level of diacetly was inversely related to titratable acidity, acetaldehyde and ethanoic acid. From ketones with high carbones 2-undecanone and 2-pentadecanone were higher than 2-butanone, 2-nanonane and 2-tridecanone. These ketones are related to fat content of yoghurt. Among short chain free fatty acids, ethanoic (acetic) acid was the most abundant in yoghurts, followed by hexanoic, octanoic and butanoic acids. These differences in detected chemical compositions of volatile compounds and free fatty acids would be applicable to predict flavor, nutritional value, quality control or shelf-life of the commmercial set-type Turkish yoghurts.
基金Indian National Centre for Ocean Information Services(INCOIS)of the Ministry of Earth Science of Indiathe INSPIRE fellowship of Department of Science and Technology of India
文摘The spatial distribution of physico-chemical parameters（sea surface temperature（SST）, p H, sea surface salinity（SSS）, dissolved oxygen（DO） and Secchi depth） along with filterable nutrients（dissolved inorganic nitrate（DIN）,dissolved inorganic phosphate（DIP） and reactive silicate（DSi）） are measured in the winter months of November,December, January and February for four consecutive years from 2009–2010 to 2012–2013 on the shallow continental shelf（〈20 m bathymetry） of the coastal waters（up to 18 km away from shoreline） of the northern Bay of Bengal（n Bo B） during the highest high tide（HHT） and lowest low tide（LLT） hours for the first time. The variability of the coastal biogeochemical environment is assessed during the HHT and LLT hours and for this purpose, seawater samples are collected from seven different locations of a transect in the coastal region. Physicochemical parameters（except SST） show significant difference in magnitude during the HHT and LLT hours respectively. p H, SSS and DO are found to increase in the HHT hours and vice-versa. The data reveal that during the LLT hours, a relative increase of freshwater input in the n Bo B can have elevated the nutrient concentration compared with that observed during the HHT hours. The ratio of nutrient concentration is found to deviate significantly from the Redfield ratio. The abundance of DIP is much higher compared with that of DIN and DSi.The anthropogenic sources of DIP from the upstream flow（especially the domestic effluent of several metropolises） can be mainly attributed behind such an observation. In order to characterize and establish the trend of such variation in such an important bio-climatic region, long-term and systematic ecosystem monitoring in the coastal water of the n Bo B northern Bay of Bengal should be carried out throughout the year.
文摘To contribute to the valorization of local materials, the physico-chemical and mineralogical characterization of two clay materials MJ and MN collected in the Mayo Tsanaga river which crosses the Makabaye district of Maroua (Cameroon) was carried out. For this purpose, various methods of characterization have been used, namely granulometric analysis, Atterberg limits, X-ray fluorescence spectrometry and X-ray diffraction. It is apparent from the granulometry that the clay materials studied titrate 33.77% of clays for MJ against 44.13% for MN. The plasticity indices Ip with values IpMJ = 19.27% and IpMN = 23.4% place the materials in the plastic domain and offer them the possibility to being shaped into objects. The chemical composition of the MJ and MN materials reveals that the silicon oxide SiO2, the aluminumoxide Al2O3 and iron oxide Fe2O3 are their main constituents. The X-ray diffraction of the MJ and MN materials shows that they consist mainly of quartz with associated kaolinite, illite, montmorillonite, perlialite, dickite, nacrite, amesite, albite, brookite and anorthite. In addition to these, 2/1 minerals such as muscovite, nontronite, glauconite, and phlogopite are also identified in the MJ material. The peaks of sanidine, microcline and gismondine are also found in the MN material. The materials being rich in clay minerals 2/1 can be valorized in the adsorption and the absorption of the oils and greases and in the waterproofing of the grounds. The presence of quartz, kaolinite and illite is undoubtedly favorable for the manufacture of ceramic products in terracotta. These products will be obtained at a relatively lower temperature due to illite, feldspars and iron minerals that provide vitrification during firing by forming eutectics. The aluminosilicate amorphous phases contained in the studied materials can be exploited to produce geopolymer cements and concretes.
文摘Thirty-one duplicate and similar named rice germplasms of Bangladesh were studied to assess the genetic variation for the agro-morphological and physico-chemical traits and simple sequence repeat banding patterns during 2009–2012 at Bangladesh Rice Research Institute. The range of variations within the cultivar groups showed higher degree. The principal component analysis showed that the first five components with vector values > 1 contributed 82.90% of the total variations. The cluster analysis grouped the genotypes into four clusters, where no duplicate germplasm was found. The highest number(11) of genotypes was constellated in cluster I and the lowest(3) in cluster II. The intra- and inter-cluster distances were the maximum in cluster I(0.93) and between clusters I and IV(24.61), respectively, and the minimum in cluster IV(0.62) and between clusters I and III(5.07), respectively. The cluster mean revealed that the crosses between the genotypes of cluster I with those of clusters II and IV would exhibit high heterosis for maximum good characters. A total of 350 alleles varied from 3(RM277) to 14(RM21) with an average of 7.8 per locus were detected at 45 microsatellite loci across the 31 rice accessions. The gene diversity ranged from 0.48 to 0.90 with an average of 0.77, and the polymorphism information content values from 0.44(RM133) to 0.89(RM206) with an average of 0.74. RM206, RM21, RM55, RM258 and RM433 were considered as the best markers on the basis of their higher polymorphism information content values. The dendrogram from unweighted pair-group method with arithmetic average clustering also classified the genotypes into four groups, where group IV comprised of 20 genotypes and group III of one genotype, but no duplicate was found. Finally, similar and duplicate named rice germplasms need to be conserved in gene bank as are distinct from each other.
文摘The deterioration of water quality in lakes constitutes an environmental problem faced by humanity. The Nkolbisson artificial lake which is located downstream of the Abiergue and Mintotomo streams in Yaounde is under the influence of various forms of pollution, mostly resulting from human activities. There is proliferation of algae on the lake surface that consumes the available oxygen in the lake. The main objective of the current study is to evaluate the different forms of pollutants in the lake, in order to propose efficient solutions for a suitable management strategy, basing on the physico-chemical and biological analysis. The lake retains an average of 2535.49 tons/year of suspended solids in the rainy season and 1438.05 tons/year in the dry season. The range of dissolved oxygen (5.2 - 3.8 mg/l);pH (7.8 - 6.8);temperature (23.9°C - 23.1°C);electrical conductivity (266.1 - 87.3 μS/cm);turbidity (22.3 - 10 UNT);suspended solid (240 - 40 mg/l);BOD (55 - 8 mg/l);COD (76 - 87.3 mg/l). Biologically, faecal coliforms fluctuates between (42 × 102 - 425 × 103 FCU/100 ml), faecal streptococci (8 × 103 - 158 × 103 FCU/100 ml) and total Coliform (15 × 103 - 78 × 106 FCU/100 ml) evidence that, the studied lake is highly polluted. Consequently the lake retains an average of 2888.7 tons/year of suspended matter.
