Preparation and characteristics of biosilica derived from marine diatom biomass of Nitzschia closterium and Thalassiosira

In this study, biosilica of high purity was successfully prepared from marine diatom （Nitzschia closterium and Thalassiosira） biomass using an optimized novel method with acid washing treatment followed by thermal treatment of the biomass. The optimal condition of the method was 2% diluted HCl washing and baking at 600℃. The SiO2 contents of N. closterium biosilica and Thalassiosira biosilica were 92.23% and 91.52%, respectively, which were both higher than that of diatomite biosilica. The SiO2 morphologies of both biosilica are typical amorphous silica. Besides, IV. closterium biosilica possessed micropores and fibers with a surface area of 59.81 m^2/g. And Thalassiosira biosilica possessed a mesoporous hierarchical skeleton with a surface area of 9.91 m^2/g. The results suggest that the biosilica samples obtained in this study present highly porous structures. The prepared porous biosilica material possesses great potential to be used as drug delivery carrier, biosensor, biocatalyst as well as adsorbent in the future.

Production and Quality Evaluation of Pringles from Composite Flour of Cocoyam and Wheat Flour

Work assessed ＂Pringles＂ as an imitate snack produced from composite flour of cocoyam and wheat. This was carried out in order to exploit the nutritional and aesthetic value of cocoyam （Colocasia escullenta Vat.） to improve the overall quality of the Pringles as against its production from potato and wheat composite flour. Composite flour （100%：0%, 90%：10%, 80%：20%, 70%：30%, 60%：40% and 50%：50%） of cocoyam and wheat respectively as the major raw materials were adopted and used for the production of the Pringles. Physicochemical analysis （pH, water absorption capacity （WAC）, bulk density （BD） and swelling capacity （SC））; proximate analysis （protein, fats, ash, moisture and carbohydrate content） and sensory evaluation （colour, texture, taste and overall acceptability） were carried out on the samples produced using standard methods. Physicochemical analysis showed the pH of 5.48 to 6.61, WAC （12.00 to 17.50）, BD （1.43 to 1.56） and SW （1.03 to 1.38）. However, sample with 10% cocoyam and 90% wheat composite flour gave the best physicochemical properties of pH （5.98）, WAC （14.00）, BD （1.56） and SC （1.38）. The proximate analysis showed that carbohydrate content ranging between 53.36 to 61.12, and protein content （8.17 to 12.29）, fat content （16.67 to 23.97）, ash content （3.49 to 45.53）, fiber content （1.71 to 2.83） and moisture content （8.76 to 14.54）. Sample B equally gave the nutrient proximate combination of appreciable percentage on the average. The result of the sensory evaluation showed that there is no significant difference between the samples produced in terms of aroma. There is a significant different between samples A, B and the remaining samples in terms of colour and taste. On the overall acceptability, samples A, C and D showed no significant difference but the highest mean score was found with sample B. Conclusively, acceptable snack （Pringles） can be produced from cocoyam and wheat in ratio 90%： 10%, respectively.

Preparation and coking properties of coal maceral concentrates

The concentrates with different maceral contents were obtained from Kailuan coking coals with different coal ranks(Ro;ranvarying from 0.88%to 1.73%)by float–sink separation in lab.Then these concentrates were characterized by proximate analysis,ultimate analysis,petrography analysis and coking index determination.The results show that the vitrinite is characterized as nature of lower carbon content,higher hydrogen content,higher volatile matter and stronger caking property compared to inertinite.The relationships between variation rate of volatile matter and maximum volatile matter and coal ranks are identified,and a linear model is developed for fast determination of the maceral contents.Compared to inertinite-rich concentrate,the blending ratio of vitrinite-rich concentrate is increased by 13%,which is considered to be a potential technique based on maceral separation for expanding the coking coal resources.

Effect and quantitative evaluation of CO_2 derived from organic matter in coal on the formation of tight sandstone reservoirs

Tight reservoirs are widely distributed, especially in coal measure strata. Identification of the densification mechanism of the tight sandstone reservoirs is critical in effectively exploring and exploiting tight gasoil resources. In this study, the gas for mation from type III organic matter in coal was kinetically modeled for the whole diagenetic stage, from the shallow buried biogas generation stage to the deep buried thermal gas generation stage. The results demonstrated that during hydrocarbon formation, quantities of nonhydrocarbon gases, such as CO2, were generated. The proportion of CO2 is about 50%70% of that of the C15, which far exceeds the CO2 content （05%） in the natural gas in the sedimentary basins. Geological case study analysis showed that a considerable part of the ＂lost＂ gaseous CO2 was converted into carbonate cement under favorable envi ronments. Under the ideal conditions, the volume of the carbonate cement transformed from total CO2 generated by 1 m3 coal （Junggar Basin Jurassic, TOC 67%） can amount to 0.32 m3. Obviously, this process plays a very important role in the for mation of tight sandstone reservoirs in the coal measures. Our results also show that the kinetic generation processes of Ci5 and CO2 are asynchronous. There are two main stages of CO2 generation, one at the weak diagenetic stage and the other at the overmature stage, which are different from largescale multistage hydrocarbon gas generation. Therefore, we can understand the mechanism of tight gas charging by determining the filling time for a tight gas reservoir and the key period of CO2 genera tion. Further analysis and correlation studies of a specific region are of great significance for determining the mechanism and modeling gas charging in tight reservoirs. It should be noted that the formation of tight sandstone reservoirs is the combined result of complex organicinorganic and waterrockhydrocarbon interactions. The details of spatial and temporal distributions of the carbonate cement derived from the organic C02, which combines with metal ions （Ca/Mg/Fe） in the formation water, should be further investigated.

Phytosterol content and the campesterol:sitosterol ratio influence cotton fiber development: role of phytosterols in cell elongation

Phytosterols play an important role in plant growth and development, including cell division, cell elongation, embryogenesis, cellulose biosynthesis, and cell wall formation. Cotton fiber, which undergoes synchronous cell elongation and a large amount of cellulose synthesis, is an ideal model for the study of plant cell elongation and cell wall biogenesis. The role of phytosterols in fiber growth was investigated by treating the fibers with tfidemorph, a sterol biosynthetic inhibitor. The inhibition of phy- tosterol biosynthesis resulted in an apparent suppression of fiber elongation in vitro or in planta. The determination of phy- tosterol quantity indicated that sitosterol and campesterol were the major phytosterols in cotton fibers; moreover, higher con- centrations of these phytosterols were observed during the period of rapid elongation of fibers. Furthermore, the decrease and increase in campesterol：sitosterol ratio was associated with the increase and decease in speed of elongation, respectively, dur- ing the elongation stage. The increase in the ratio was associated with the transition from cell elongation to secondary cell wall synthesis. In addition, a number of phytosterol biosynthetic genes were down-regulated in the short fibers of ligon lintless-1 mutant, compared to its near-isogenic wild-type TM-1. These results demonstrated that phytosterols play a crucial role in cot- ton fiber development, and particularly in fiber elongation.