Utilization of waste cellulose

Native outer, inner and whole bark, and paper mill waste bark have been studied and compared. Extraction with cold and warm water and different chemical pretreatments (H₂SO₄, NaOH, and NaClO) have been used to improve the accessibility of the cellulose fraction of the substrate to the enzymes and hence to increase the yield of formation of glucose.     

Effect of ultrasound power on HCl leaching kinetics of impurity removal of aphanitic graphite

This study aimed to investigate the effect of ultrasonic power and temperature on the impurity removal rate during conventional and ultrasonic-assisted leaching of aphanitic graphite. The results showed that the ash removal rate increased gradually (∼50 %) with the increase in ultrasonic power and temperature but deteriorated at high power and temperature. The unreacted shrinkage core model was found to fit the experimental results better than other models. The Arrhenius equation was used to calculate the finger front factor and activation energy under different ultrasonic power conditions. The ultrasonic leaching process was significantly influenced by temperature, and the enhancement of the leaching reaction rate constant by ultrasound was mainly reflected in the increase of the pre-exponential factor A. Ultrasound treatment improved the efficiency of impurity mineral removal by destroying the inert layer formed on the graphite surface, promoting particle fragmentation, and generating oxidation radicals. The poor reactivity of hydrochloric acid with quartz and some silicate minerals is a bottleneck limiting the further improvement of impurity removal efficiency in ultrasound-assisted aphanitic graphite. Finally, the study suggests that introducing fluoride salts may be a promising method for deep impurity removal in the ultrasound-assisted hydrochloric acid leaching process of aphanitic graphite.     

Laser Induced Breakdown Spectroscopy machine for online ash analyses in coal

Presently, online coal ash content monitoring is performed by PGNAA (Prompt Gamma Neutron Activation Analyses) machines. Laser Detect Systems has developed an online mineral analysis system using Laser Induced Breakdown Spectroscopy (LIBS). The main advantages of the system are that it is without a radioactive source, compact (1.5 m × 0.8 m × 1.3 m), comparatively light (250 kg) and easy to install. The main disadvantage is that a LIBS system analyzes surface chemistry of the mineral exclusively and not the volume. To prove the LIBS machine analytical ability for coal ash content evaluation, a trial was arranged at Optimum Colliery (South Africa). The LIBS machine was installed in line with a PGNAA machine and laboratory data served as a referee in the final assessment for analytical accuracy. The trial was carried out over a four month period. This paper presents the successful trial results achieved for accurate (at least +/− 0.5% mean absolute error) online coal ash content monitoring.     

Cytotoxic,antibacterial and antioxidant activities of extracts of the bark of Melia azedarach (China Berry)

Nature provides a variety of drugs and medicinal agents derived from plants. This study was conducted to determine antimicrobial, antioxidant and cytotoxic activities of extracts of Melia azedarach bark with methanol/water (9:1 v/v), chloroform, butanol, hexane, water and ethyl acetate. For the determination of the antimicrobial activities, the agar well diffusion method was employed. Cytotoxicity was studied by brine shrimp lethality assay; antioxidant activities were measured using 1,1-diphenyl-2-picrylhydrazyl. The chloroform extract was active against Enterobacter aerogenes and Proteus mirabilis, the ethyl acetate extract had highest antibacterial spectrum against Pseudomonas aeruginosa, the n-hexane extract had highest inhibition against E. aerogenes, the aqueous extract showed highest activities against P. mirabilis, the butanol fraction showed highest activities against E. aerogenes and the methanolic extract was highly active against P. mirabilis.     

比色法测定蒙药铜灰体系中产生的*OH自由基

根据细胞色素C的氧化特性,采用比色法测定蒙药铜灰体系中产生的·OH自由基。实验证明,以盐酸羟胺为还原剂,在磷酸二氢钾缓冲溶液中测定,效果较好。该体系不受β-胡萝卜素的抑制,仅受硫脲的抑制,说明蒙药铜灰可作为筛选抗·OH自由基的消除剂,并具有“燥脓、清肺、肝之热”等功能。     

(3R,4R)-欧洲榆小蠹聚集信息素的合成

欧洲榆小蠹原产欧洲榆树生长区,美国、加拿大及非洲北部也有分布,其成虫及幼虫蛀食榆树皮,并能传播榆疫病,从而影响榆树生长．Ｐｅａｒｃｅ等分离出其聚集信息素并鉴定其分子结构为（—）４甲基３庚醇（１）［１］,Ｍｏｒｉ等研究结果确定出其天然产物构型为...     

煤粉燃烧颗粒粒子云辐射特性的研究

分析了在560nm的测量波长处煤粉炉中炭粒和飞灰粒子云的辐射特性。利用Mie理论,分别计算了燃烧器出口和炉膛的上部颗粒粒子云的辐射特性,发现在燃烧器出口区,炭粒对颗粒总体辐射减弱系数的影响较大,占90%以上;而在炉膛的上部,飞灰的影响较大。从数值计算结果中可以看出,飞灰粒子云的散射率高达91.6%,其对辐射的散射作用比吸收更强,而炭粒子的散射率仅为50%。     

Phyto-Functionalized Silver Nanoparticles Derived from Conifer Bark Extracts and Evaluation of Their Antimicrobial and Cytogenotoxic Effects

Silver nanoparticles synthesized using plant extracts as reducing and capping agents showed various biological activities. In the present study, colloidal silver nanoparticle solutions were produced from the aqueous extracts of Picea abies and Pinus nigra bark. The phenolic profile of bark extracts was analyzed by liquid chromatography coupled to mass spectrometry. The synthesis of silver nanoparticles was monitored using UV-Vis spectroscopy by measuring the Surface Plasmon Resonance band. Silver nanoparticles were characterized by attenuated total reflection Fourier transform infrared spectroscopy, Raman spectroscopy, dynamic light scattering, scanning electron microscopy, energy dispersive X-ray and transmission electron microscopy analyses. The antimicrobial and cytogenotoxic effects of silver nanoparticles were evaluated by disk diffusion and Allium cepa assays, respectively. Picea abies and Pinus nigra bark extract derived silver nanoparticles were spherical (mean hydrodynamic diameters of 78.48 and 77.66 nm, respectively) and well dispersed, having a narrow particle size distribution (polydispersity index values of 0.334 and 0.224, respectively) and good stability (zeta potential values of −10.8 and −14.6 mV, respectively). Silver nanoparticles showed stronger antibacterial, antifungal, and antimitotic effects than the bark extracts used for their synthesis. Silver nanoparticles obtained in the present study are promising candidates for the development of novel formulations with various therapeutic applications.     

Composition dependent model for the prediction of syngas ash deposition in turbine gas hotpath

An improved physical model to predict flyash deposition is developed and discussed in this paper. This model differs from its predecessor ( [Rozati et al., in press] and [Sreedharan and Tafti, 2009] by accounting for deposition of syngas ash particles below the ash softening temperature. The modified deposition model is based on the critical viscosity approach. To test this model, deposition of ash particles impacted on a flat, 45° wedge shape geometry is computed and the results obtained from the numerical model are compared to Crosby et al. (2007). Large Eddy Simulation (LES) is used to model the flow field and flyash particles are modeled using a discrete Lagrangian framework. Results quantify deposition for 4 μm particles of various ash composition samples. Most of the deposition occurs at the stagnation region of the target plate. At 1456 K, out of all the ash samples considered in this study, WY and ND ash sample show the highest capture efficiency (15%) and KL1 ash sample exhibits the lowest capture efficiency (0.02%). In general, capture efficiencies for all ash samples followed an exponential trend with temperature. Additionally, this model is also compared to results obtained from the flat plate deposition experiments conducted here at Virginia Tech using PVC particles (Wood et al., 2010). In the case of PVC particles, the sticking probability in the deposition model assumed an exponential increase in deposition rate with temperature and was calibrated with one experimental data point. The results obtained from this model for PVC particles showed excellent agreement with the experimental measurements over a range of temperatures.     

Radiation and chemical pretreatment of cellulosic waste

RADIATION AND CHEMICAL PRETREATMENT OF CELLULOSIC WASTE. Combination pretreatment of cellulosic wastes such as corn stalk, cassava bark and peanut husk were studied using chemical and irradiation of electron beam. The effect of 2 % NaOH and irradiation at the doses of 100, 300 and 500 kGy on the cellulosic wastes were evaluated by measurement of the glucose yield in enzymatic hydrolysis. Irradiation was carried out with an electron beam machine EPS-300 (Energy 300 kev, current 50 mA). The result shows that the glucose yield were higher by increasing of dose irradiation and treated with 2 % of NaOH especially in corn stalk. The glucose yield of corn stalk were 20 % in untreated samples and increases to 43 % after treated with electron beam irradiation at the dose of 500 kGy and 2 % NaOH. Cassava bark and peanut husk show the glucose yield are only 3.5, and 2.5% respectively. The effect of E-beam current in enzymatic hydrolysis of corn stalk, and preliminary studied E-beam radiation pretreatment of cassava bark are also reported.