表干型保温冒口的研制及应用

表干型保温冒口的研制及应用广西大学梧州分校（梧州５４３００２）萧泽新强化冒口补缩是保证铸件质量的重要工艺措施之一。普通冒口只有１４％～２０％的金属液能够有效地用于补缩铸件，而保温冒口的金属利用率可提高到３０％～５０％，铸件的工艺出品率明显提高。我国从...

表干型保温冒口的研究与应用

本文介绍一种以膨胀珍珠岩、菱苦土、石英砂和粘结剂(工业糖浆或水玻璃)为原料研制成功的一种新型保温冒口.它突出的创新点是现配现用,表面干燥后即可浇注.从而能有效地缩短铸件生产周期,提高生产效率,有较显著的经济效益与推广价值.

铸铁件表干型铸造的质量控制

我公司应用表干型生产铸铁件质量基本稳定，废品率在5．8％以下，铸铁件的表面和内在质量完全可以和烘干型相媲美。表干型铸造生产要求具有较高的技术和经验，否则铸件易产生多肉（大包、凸起）、夹砂、气孔及砂眼等缺陷。下面简述表干型在铸造生产中的质量控制及应用要点。

强化剂表干型粘土砂的应用实践

本文介绍了强化剂表干型粘土砂的应用技术.实践表明,采用该型砂对于改善铸件表面质量,特别是消除夹砂、结疤缺陷,具有显著效果.

表干型用简易喷枪

采用表干型铸造,既可缩短生产周期,又能节约燃料。我们厂在生产400×100炼胶机底座大型铸件(重2.1t,外形尺寸:3800×1600×450mm)时,采用自制简易喷枪将干型铸造改为表干型铸造,结果缩短生产周期1/2,降低能源消耗65%,收到良好的经济效益。

Evaluation of the WRF Model with Different Land Surface Schemes: A Drought Event Simulation in Southwest China during 2009–10

The authors examined the performance of version 3.4.1 of the Weather Research and Forecasting Model(WRF) with various land surface schemes in simulating a severe drought event in Southwest China. Five numerical experiments were completed using the Noah land surface scheme, the Pleim-Xiu land surface scheme, the Noah-MP land surface schemes, the Noah- MP scheme with dynamic vegetation, and the Noah-MP scheme with dynamic vegetation and groundwater processes. In general, all the simulations reasonably reproduced the spatial and temporal variations in precipitation, but significant bias was also found, especially for the spatial pattern of simulated precipitation. The WRF simulations with the Noah-MP series land surface schemes performed slightly better than the WRF simulation with the Noah and Pleim-Xiu land surface schemes in reproducing the severe drought events in Southwest China. The leaf area index(LAI) simulated by the different land surface schemes showed significant deviations in Southwest China. The Pleim-Xiu scheme overestimated the value of LAI by a factor of two. The Noah-MP scheme with dynamical vegetation overestimated the magnitude of the annual cycle of the LAI, although the annual mean LAI was close to observations. The simulated LAI showed a long-term lower value from autumn 2009 to spring 2010 relative to normal years. This indicates that the LAI is a potential indictor to monitor drought events.

Epithelial cells with hepatobiliary phenotype:Is it another stem cell candidate for healthy adult human liver?

AIM： To investigate the presence and role of liver epithelial cells in the healthy human adult liver. METHODS： Fifteen days after human hepatocyte primary culture, epithelial like cells emerged and started proliferating. Cell colonies were isolated and sub- cultured for more than 160 d under specific culture conditions. Cells were analyzed for each passage using immunofluorescence, flow cytometry and reverse transcription-polymerase chain reaction （RT-PCR）. RESULTS： Flow cytometry analysis demonstrated that liver epithelial cells expressed common markers for hepatic and stem cells such as CD90, CD44 and CD29 but were negative for CD34 and CDl17. Using immunofluorescence we demonstrated that liver epithelial cells expressed not only immature （α-fetoprotein） but also differentiated hepatocyte （albumin and CK-18） and biliary markers （CK-7 and 19）, whereas they were negative for OV-6. RT-PCR analysis confirmed immunofluorescence data and revealed that liver epithelial cells did not express mature hepatocyte markers such as CYP2B6, CYP3A4 and tyrosine amino-transferase. Purified liver epithelial cells were transplanted into SCID mice. One month after transplantation, albumin positive cell foci were detected in the recipient mouse parenchyma. CONCLUSION： According to their immature and bipotential phenotype, liver epithelial cells might represent a pool of precursors in the healthy human adult liver other than oval cells.

Statistical Characteristics of the Received Signal for Stochastic Surface Models

This paper describes the stochastic model of the scattered electromagnetic field.Unlike common_used functional_determined models the proposed is characterised by amplitude/phase fluctuation of the received signal.This paper derives the statistical characteristic of the input signal and describes algorithm for its estimation in post_processing and real_time processing modes.Achieved characteristics allow the mapping and estimation of the surface models more accurate,moreover,such processing increase space resolution of synthetic aperture radar.

Symbiotic and Phenotypic Characteristics of Rhizobia Nodulaing Cowpea （Vigna Unguiculata L. Walp） Grown in Arid Region of Libya （Fezzan）

Symbiotic and phenotypic characteristics of thirty rhiobial isolates obtained from root nodules of two cowpea （Vigna unguiculata L. Walp） cultivars that grown in different sites of Fezzan （Southern part of Libya） were studied. Cultural characteristics and cross-nodulation with Arachis hypogega and Faidherbia albida showed that they were slow-growing rhizobia. Each isolate was found to coexist with non-symbiotic bacteria similar in their cultural characteristics to fast-growing rhizobia. All isolates formed symbiosis with the test plants, but different in their nitrogen-fixation efficiency. Numerical analysis of phenotypic characteristics showed that at boundary level of 70% average similarity, the isolates formed four distinguished groups and two isolates remained separate. Most isolates exhibited wide tolerance to acidity, alkalinity and extreme temperatures. They also resistant to some heavy metals such as mercury, copper, zinc, lead, cadmium and aluminum at low concentrations and antibiotics like polymyxin, colistin, bacitracin and nalidixic acid. Isolates displayed different response to salinity ranging from sensitive, which unable to grow in 1% NaCI to resistant and grow at 2% NaCl or above. Urea was hydrolyzed by most of them and carbohydrates utilizations were different. Sucrose and maltose were metabolized by most of the test isolates, whereas, monosaccharide and sugar alcohols were poorly utilized.

Expression of bcl-2 protein in chronic hepatitis C:Effect of interferon alpha 2b with ribavirin therapy

AIM: Mechanisms responsible for persistence of HCV infection and liver damage in chronic hepatitis C are not clear. Apoptosis is an important form of host immune response against viral infections. Anti-apoptotic protein bcl-2 expression on liver tissue as well as the influence of interferon alpha 2b (IFNa2b) and ribavirin (RBV) were analyzed in patients with chronic hepatitis C. METHODS: In 30 patients with chronic hepatitis C (responders - R and non-responders - NR) treated with IFNα2b+RBV, protein bcl-2 was determined in hepatocytes and in liver associated lymphocytes before and after the treatment. RESULTS: The treatment diminished bcl-2 protein accumulation in liver cells in_patients with hepatitis C (P<0.05). Before and after the therapy, we detected bcl-2 protein in R in 87±15% and 83±20% of hepatocytes and in 28±18% and 26±10% of liver-associated lymphocytes, respectively. In NR, the values before treatment decreased from 94±32% to 88±21% of hepatocytes and 39±29% to 28±12% of lymphocytes with bcl-2 expression. There was no statistical correlation between bcl-2 expression on liver tissue with inflammatory activity, fibrosis and biochemical parameters before and after the treatment. CONCLUSION: IFNα2b+RBV treatment, by bcl-2 protein expression decrease, enables apoptosis of hepatocytes and associated liver lymphocytes, which in turn eliminate hepatitis C viruses.

Effect of interferon-γ and tumor necrosis factor-α on hepatitis B virus following lamivudine treatment

AIM： To evaluate anti-hepatitis B virus （HBV） activity and cytotoxicity of interferon-α, （IFN-3,） and tumor ne- crosis factor-α （TNF-α） following lamivudine treatment of HepG2.2.15 cells. METHODS： HepG2.2.15 cells were treated with 2 pmol/L lamivudine for 16 d （lamivudine group）, cultured for 10 d, followed by 5 ng/ml TNF-α and 1000 U/mL IFN-γ, for 6 d （cytokine group）, or treated with 2 ~tmol/L lami- vudine for 10 d followed by 5 ng/mL TNF-α and 1000 U/mL IFN-γ, for 6 d （sequential group）, or cultured without additions for 16 d （control group）. Intracellular DNA was extracted from 3 ×10^ HepG2.2.15 cells from each group. The extracted DNA was further purified with mung bean nuclease to remove HBV relaxed circu- lar DNA that may have remained. Both HBV covalently closed circular DNA （cccDNA） and HBV DNA were exam- ined with real-time polymerase chain reaction. The titers of hepatitis B surface antigen （HBsAg） and hepatitis B e antigen （HBeAg） were quantified with enzyme-linkedimmunosorbent assay. Cell viability was measured with the cell counting kit-8 assay. RESULTS： Compared to lamivudine alone （22.63%±0.12%）, both sequential （51.50% ± 0.17%, P = 0.034） and cytokine treatment （49.66% ± 0.06%, P = 0.041） showed a stronger inhibition of HBV cccDNA; the dif- ference between the.sequential and cytokine groups was not statistically significant （51.50% ± 0.17% vs 49.66% ± 0.06%, P = 0.88）. The sequential group showed less inhibition of HBV DNA replication than the lamivudine group （67.47% ±0.02% vs 82.48% ± 0.05%, P = 0.014）; the difference between the sequen- tial and cytokine groups was not statistically significant （67.47% ± 0.02% vs 57.45% ± 0.07%, P = 0.071）. The levels of HBsAg and HBeAg were significantly de- creased in the sequential treatment group compared to the other groups [HBsAg： 3.48 ± 0.04 （control）, 3.09 ± 0.08 （lamivudine）, 2.55± 0.13 （cytokine）, 2.32 ± 0.08 （sequential）, P = 0.042 for each between-group comparison; HBeAg 3.48 ± 0.01 （control）, 3.08 ± 0.08 （lamivudine）, 2.57 ± 0.15 （cytokine）, 2.34 ± 0.12 （se- quential）, P = 0.048 for each between-group compari- son]. Cell viability in the cytokine group was reduced to 58.03% ± 8.03% compared with control cells （58.03% ± 8.03% vs 100%, P = 0.000）. Lamivudine pretreat- ment significantly reduced IFN-γ, ± TNF-αmediated toxicity of HepG2.2.15 cells [85.82% =1= 5.43% （sequen- tial） vs 58.03% ± 8.03% （cytokine）, P = 0.002]. CONCLUSION： Sequential treatment overcame the lower ability of lamivudine alone to inhibit cccDNA and precluded the aggressive cytotoxicity involving IFN-y and TNF-α by decreasing the viral load.

Understanding the Safety, Health and Environmental （SHE） Challenges of Xenobiotics and Their Remedial Approaches

With the use of over 100,000 industrially produced chemicals, there have been several concerns on human health and environment. Most of these chemicals are exposed into the natural environment during the life cycles of their production, transportation, storage, consumption, and as by-products and wastes. The rising rates of cancer, obesity, and infertility suggests that there are compounds recently introduced to the environment that have altered the chemistry of the human body, and it is only with the monitoring of xenobiotics such as Bisphenol A （BPA）, nonyphenols, estrogen （natural and synthetic） and other endocrine-disrupting compounds （EDCs） that patterns and links could be drawn. This paper investigates the safety, environmental and health （SHE） impacts caused by BPA, nonyphenols and estrogens. Derived from petroleum, bisphenol A is used in manufacturing plastic consumer products, including certain water bottles, in dental sealants for children＇s teeth, and in resins used to line tin cans. Nonyphenol is one of the by-products of alkylphenolpolyethoxilates which is widely used as nonionic surfactants. Synthetic estrogen used for birth control pills as well as natural estrogen excreted by women through urine enters the domestic wastewater streams. These compounds are considered to be EDCs and have severe SHE concerns. In this paper, the challenges of entry of these compounds （xenobiotics） into nature, health and environmental issues and their remediation have been reviewed in detail.

Biological features of mesenchymal stem cells from human bone marrow

Objective To study the biological characteristics of mesenchymal stem cells (MSCs) from human bone marrow. Methods A culture of mesenchymal stem cells was initiated from bone marrow low-density mononuclear cells separated by Percoll Centrifugation and maintained in low-glucose Dulbecco's modified Eagle's medium (DMEM) with 10% selected fetal calf serum. Cell growth pattern and its responses to cytokines were evaluated by trypan blue exclusion and MTT test, respectively. Cell cycle and surface antigenic features were analyzed by flow cytometry technique. Cytochemistry characteristics of MSCs were determined. Results Easy-handling methods to isolate and culture expand MSCs were developed in this study. MSCs were unique in their phenotypes. They were positive for CD29, CD44, CD166, and negative for CD34, CD45, HLA-DR and Ulex europaeus. Cytochemistry evaluation showed that MSCs were homogeneously positive for acid α-naphthl acetate esterase (ANAE), glycogen (periodic acid Schiff reaction, PAS), and negative for acid phosphatase (ACP) and the Sudan black reaction (SB). Around 5% of them were positive for alkaline phosphatase (ALP). The cells had a population doubling time of 30 hours and cell cycle analysis showed that approximately 10% of them were in S phase. MSCs grew at significantly different rates when incubated in the presence of various recombinant human cytokines, of which interferon γ, tumor necrosis factor α, stem cell factor and insulin-like growth factor promoted the proliferation of MSCs dramatically, while others tested had no effects on cell growth. Conclusions MSCs are a homogenous population of cells that have unique growth, phenotypical and cytochemical characteristics. Furthermore, the diverse responses of MSCs to different cytokines provide a clue for the selection of optimal expansion and maintenance of MSCs.

A comparative study of the specific surface area and pore structure of different shales and their kerogens

The pore structures and controlling factors of several different Paleozoic shales from Southern China and their kerogens were studied using nitrogen adsorption and scanning electron microscopy methods. The results indicate that： 1） The specific surface area is 2.22-3.52 m2/g and has no correlation with the TOC content of the Permian Dalong Formation shales, nanopores are extremely undeveloped in the Dalong Formation kerogens, which have specific surface areas of 20.35-27.49 me/g; 2） the specific surface area of the Silurian Longmaxi Formation shales is in the range of 17.83-29.49 m2/g and is positively correlated with TOC content, the kerogens from the Longmaxi Formation have well-developed nanopores, with round or elliptical shapes, and the specific surface areas of these kerogens are as high as 279.84-300.3 m2/g; 3） for the Niutitang Formation shales, the specific surface area is 20.12-29.49 m2/grock and increases significantly with increasing TOC and smectite content. The Niuti- tang Formation kerogens develop a certain amount of nanopores with a specific surface area of 161.2 m2/g. Oil shale was also examined for comparison, and was found to have a specific surface area of 19.99 m2/g. Nanopores are rare in the Youganwo Formation kerogen, which has a specific surface area of only 5.54 m2/g, suggesting that the specific surface area of oil shale is due mainly to the presence of smectite and other clay minerals. The specific surface area and the number of pores present in shales are closely related to TOC, kerogen type and maturity, smectite content, and other factors. Low-maturity kerogen has very few nanopores and therefore has a very low specific surface area, whereas nanopores are abundant in mature to over- mature kerogen, leading to high specific surface areas. The Longmaxi Formation kerogen has more developed nanopores and a higher specific surface area than the Niutitang Formation kerogen, which may be due to differences in the kerogen type and maceral components. A high content of smectite may also contribute to shale surface area. The pore volume and specific sur- face area of low-maturity kerogens are mainly attributable to pores with diameters above 10 nm. By contrast, the pore volume of mature kerogens consists predominantly of pores with diameters above 10 nm with some contribution from about 4 nm diameter pores, while the specific surface area is due mainly to pores with diameters of less than 4 nm. Through a comparative study of the specific surface area and pore structure characteristics of different shales and their kerogens, we conclude that the Longmaxi Formation shales and Niutitang Formation shales have greater sorption capacities than the Dalong Formation shales.