蒸汽爆破过程中生物质固相得率的试验测定方法

生物质在蒸汽爆破过程中各类成分会发生多种物理化学变化,造成固相质量的理论减少;固液混合物可能被气流带出或飞溅出回收仓,造成固相质量的非理论减少。这两种因素使生物质爆破前后的物料衡算难以实现。通过对青贮玉米秸秆、小麦秸秆、玉米秸秆、玉米芯、花生壳五种生物质进行多种处理方式的对比试验,我们发现青贮玉米秸秆经2.0MPa\10min、2.4MPa\5min、2.8MPa\3min三种饱和蒸汽蒸煮工艺处理后,再以550℃\4h灼烧后的总灰分相对原料平均变化率分别为0.68%、0.38%和0.34%,其它四种生物质在蒸煮过程中灰分含量也保持了相对稳定,表明在2.8MPa压力以下的不同蒸煮工艺对不同生物质总灰分的绝对质量影响基本没有,所发生的物理化学变化基本不改变总灰分的质量。由于同温度下的蒸煮过程与汽爆过程所发生的物理化学变化类型基本相同,因此对灰分含量影响可以在很大程度上相互参照。只要保证灰分在固相中是均匀分布的,就可以通过汽爆前后总灰分或酸不溶性灰分在固相中的相对含量f0与f1确定出爆后总的固相得率v=f0/f1,并计算出固相中每种成分的爆后得率。从而为汽爆工艺优化与过程分析提供一种更为准确可靠的物料衡算分析方法。

Exopolysaccharides from Marine Bacteria

Microbial polysaccharides represent a class of important products of growing interest for many sectors of indus- try. In recent years, there has been a growing interest in isolating new exopolysaccharides (EPSs)-producing bacteria from marine environments, particularly from various extreme marine environments. Many new marine microbial EPSs with novel chemical compositions, properties and structures have been found to have potential applications in fields such as adhesives, textiles, Pharmaceuticals and medicine for anti-cancer, food additives, oil recovery and metal removal in mining and indus- trial waste treatments, etc This paper gives a brief summary of the information about the EPSs produced by marine bacteria, including their chemical compositions, properties and structures, together with their potential applications in industry.

Study of Constituents of Fractionated Extraction from Datong Coal

Datong coal was extracted with CS2, n-hexane, benzene, methanol, acetone, tetrahydro-furan（THF） and THF/methanol（1：3,v/v） mixed solvent sequentially. The extracts were analyzed with GC/MS. It is presented that group seperation of soluble organic compounds in the coal can be achieved by fractionated extraction using different solvents. The results show that CS2 was effective for extracting arenes from the coal sample, n-Hexane extractable fraction from Datong coal mainly consists of n-alkanes. A great variety of oxygen-containing compounds are dominant in the components of methanol-soluble fraction. Acyclic isoprenoids, pentecyclic triterpanes and a series of cyclohexanes with long-chain alkyl-substitutes are detected in acetone-soluble fraction. Dicyclic aramatic hydrocarbons are identified in benzene-soluble fraction and 4-6 cyclic condensed aramatic hydrocarbons are identified in THF-soluble fraction. The molecular structures detection of 1,2-dichlorobenzene, 2,4-dibromophnol, 2,4,6-tribromophenol and 4-chlorobenzophenone firstly provide information for existence form of bromine and chlorine in coal.

Nutrient composition,mineral content and the solubility of the proteins of palm weevil,Rhynchophorus phoenicis f.(Coleoptera:Curculionidae)

Adult (ADS) and larva stages of palm weevil Rhynchophorus phoenicis were analyzed for their nutritional potentials using proximate and mineral contents as indices. The early larva stage (ELS) contains the highest moisture content of 11.94% while ADS has the least value of 4.79%. The late larva stage (LLS) has the highest protein content of 10.51% while ADS contains 8.43%. Ash content is highest in ELS with a value of 2.37% and lowest in ADS with a value of 1.43%. ELS and LLS have the highest (22.14%) and lowest (17.22%) fibre contents respectively. The values of potassium, magnesium and iron in ELS were (455.00±21.21), (60.69±2.57) and (6.50±3.40) mg/kg while LLS recorded (457.50±10.61), (43.52±1.37) and (6.00±1.10) mg/kg and ADS recorded (372.50±24.75), (53.31±1.88) and (22.90±3.70) mg/kg. Chromium, phosphorus, nickel, calcium, lead, man- ganese and zinc were also detected. Copper was not detected in any of the samples. In all the developmental stages the protein solubilities were pH dependent with the minimum protein solubilities occurring at acidic pH while the maximum protein solu- bilities occurred at alkaline pH.

RIVERINE INORGANIC CARBON DYNAMICS:OVERVIEW AND PERSPECTIVE

Inorganic carbon, the great part of the riverine carbon exported to the ocean, plays an important role in the global carbon cycle and ultimately impacts the coupled carbon-climate system. An overview was made on both methods and results of the riverine inorganic carbon researches. In addition to routine in situ survey, measurement and calculation, the direct precipitation method and the gas evolution technique were commonly used to analyze dissolved inorganic carbon in natural water samples. Soil CO2, carbonate minerals and atmospheric CO2 incorporated into riverine inorganic car- bon pool via different means, with bicarbonate ion being the dominant component. The concentration of inorganic carbon, the composition of carbon isotopes （8^13C and △^14C）, and their temporal or spatial variations in the streams were controlled by carbon input, output and changes of carbon biogeochemistry within the riverine system. More accurate flux es- timation, better understanding of different influential processes, and quantitative determination of various inputs or outputs need to be well researched in future.

Synthesis of ZnO whiskers via hydrothermal decomposition route

ZnO whiskers with a length of 30-40μm and a diameter of about 1μm were synthesized by co-precipitation of ZnSO 4 and Na2CO3 solution at room temperature followed by hydrothermal treatment of the as-prepared Zn5(CO3)2(OH)6 precursor at 160 ℃for 6 h.The increase of the initial solution pH promotes the hydrothermal conversion of the particulate Zn5(CO3)2(OH)6 to ZnO whiskers.The presence of minor amount of EDTA in the hydrothermal solution promotes the one dimensional growth of ZnO whiskers,leading to the formation of ZnO whiskers with a length of 50-60μm and a diameter of 1-2μm.

Synthesis, characterization of monodispersed MgO microspheres and thermal decomposition kinetics of its precusor

Monodispersed MgO microspheres were successfully synthesized by a simple solvothermal method using PEG-400 as solvent. The samples were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM). The results reveal that the precusor was monoclinic Mg5(CO3)4(OH)2·4H2O and composed of nanosheets with the thickness of about 250 nm. By calcining the precusor at 500 °C for 5 min, cubic MgO with similar morphology was obtained. According to the SEM images, it is found that the volume ratio of PEG-400 to deionized water is considered as a crucial factor in the evolution of the morphology. Based on the SEM images obtained under different experimental conditions, a possible growth mechanism which involves self-assembly process was proposed. The thermal decomposition process of MgO precusor was studied by thermogravimetry-differential thermogravimetry(TG-DTG) at different heating rates in air. Thermal analysis kinetics results show that the most probale mechanism models of MgO precusor are An and D3, respectively. In addition, isothermal prediction was studied to quantitatively characterize the thermal decomposition process.

Chemical Composition of Meat in Castrated Male Brahman Cattle in Venezuela

Chemical composition of Brahman cattle was studied and determined in this study. Fifty males had been castrated at birth, farmed semi-intensively on the Venezuelan plain and then slaughtered at the age of 31 months with an approximate weight of 500 kilograms. The average pH value of beef was 5,84 after obtained for 24 hours after staughtering, which matches the ~atue found in similar studies made on the same breed in Venezuela （5.8）. The moisture, crude protein and ash contents correspond to the expected values of cattle, while the intramuscular fat values are slightly higher than those of the different breeds ofBos indicus. The total collagen values found in this study are either similar or lower than those found by other researches from the different breeds ofBos indicus and their crossbreeds, while the collagen solubility value （39%） was higher than the one found in other studies on the Brahman breed.