石墨层间化合物成阶过程分析

主要从插层剂插入石墨、插层剂的扩散和阶结构的转变3个方面对石墨层间化合物成阶相关的过程进行讨论。从表面扩散、成核和电子转移3个方面介绍了插层剂进入石墨层间的过程;利用单相的方法分析了层内插层剂的扩散;从有无阶数变化两个方面讨论了阶结构的转化机制。

A NOVEL SCHEME FOR HIGH POWER HIGH EFFICIENCY INVERTERS

The pulse width modulation (PWM) scheme is used in the staircase waveform inverters. The control strategy and system characteristics are analyzed. While the single pulse width modulation is used, the 12 stairs waveform inverter can achieve the output voltage regulated in a wide range of input voltage as well as the perfect output waveform. A 1 500 V input 80 kVA inverter has been deve loped. Experiments of the 80kVA inverter resulted in that the scheme is a perfect method for the development of high power converters with high efficiency.

Genetic analysis of fruit shape traits at different maturation stages in sponge gourd

The fruit shape is important quantitative trait closely related to the fruit quality. However, the genetic model of fruit shapes has not been proposed. Therefore, in the present study, analysis of genetic effects for fruit shape traits （fruit length and fruit perimeter） in sponge gourd was conducted by employing a developmental genetic model including fruit direct effects and maternal effects. Analysis approaches of unconditional and conditional variances were applied to evaluate the genetic behavior of fruit shape traits at economical and physiological maturation times. The results of variance analysis indicated that fruit length and fruit perimeter were simultaneously affected by fruit direct genetic effects and maternal effects. Fruit direct genetic effects were relatively more important for fruit shape traits at whole developmental period. The gene expression was most active at the economical maturation stage （1-12 d after flowering） for two shape traits, and the activation of gene was mostly due to direct dominance effects at physiological maturation stage （13-60 datter flowering）. The coefficients due to different genetic effects, as well as the phenotypic correlation coefficients, varied significantly between fruit shape traits themselves at various maturation stages. The results showed that it was relatively easy to improve fruit shape traits for industrial purpose by carefully selecting the parents at economical maturation stage instead of that at physiological maturation stage.

Evaluation of Maturity and Flavor of Melons Using an Electronic Nose

In this work,an electronic nose was used to evaluate the different cultivars and mature stages of melons,so as to establish a scientific method to accurately distinguish the maturity and varieties of melons. Principal component analysis (PCA) and linear discriminant analysis (LDA ) showed that immature melons could be well distinguished from mature melons using electronic nose. When PCA method was used to analyze,electronic nose could completely classify and identify the maturity of melons. Meanwhile,the electronic nose could distinguish different varieties of melons with high discrimination value. The flavor of samples under cut or no cut conditions would slightly change,leading to the variation of discrimination value among different varieties. The samples with similar flavor under no cut condition could be analyzed through cutting mode. The research built a rapid and accurate method to judge the maturity of melons instead of man sense.

Diagnostic value of gadobenate dimeglumine-enhanced hepatocyte-phase magnetic resonance imaging in evaluating hepatic fibrosis and hepatitis

AIM To evaluate the diagnostic value of gadobenate dimeglumine(Gd-BOPTA)-enhanced hepatocyte-phase magnetic resonance imaging(MRI) in evaluating hepatic fibrosis and hepatitis.METHODS Hepatocyte-phase images of Gd-BOPTA-enhanced MRI were retrospectively evaluated in 76 patients with chronic liver disease. These patients were classified into five groups according to either the histopathological fibrosis stage(S0-S4) or the histopathological hepatitis grade(G0-G4). The relative enhancement ratio(RE) of the liver parenchyma in the T1-vibe sequence was calculated by measuring the signal intensity before(SI pre) and 90 min after(SI post) intravenous injection of Gd-BOPTA using the following formula: RE =(SI post-SI pre)/SI pre. One-way analysis of variance was used to compare the difference between the relative RE in the hepatocyte phase(REh) and the stage of hepatic fibrosis and the grade of hepatitis. Pearson's productmoment correlation analysis was used to evaluate the relationship between the REh and the levels of serologic liver functional parameters.RESULTS According to histopathological hepatic fibrosis stage, the 76 patients were classified into five groups: 16 in S0, 15 in S1, 21 in S2, 9 in S3, and 15 in S4 group. According to histopathological hepatitis grade, the 76 patients were also classified into five groups: 0 in G0, 44 in G1, 22 in G2, 8 in G3, and 2 in G3 group. With regard to the stage of hepatic fibrosis, REh showed significant differences between the S2 and S3 groups and between the S2 and S4 groups(P < 0.05), but no significant difference was observed between the other groups. With regard to the grade of hepatitis, REh showed significant differences between the G1 and G2 groups and between the G1 and G4 groups(P < 0.05), but no significant difference was observed between the other groups. Increased REh showed correlations with decreased serum levels of TB, ALT and AST(P < 0.05). CONCLUSION To some extent, measuring the REh using Gd-BOPTAenhanced MRI might be a noninvasive technique for assessing the stage of hepatic fibrosis. This method is able to differentiate no/mild hepatitis from advanced hepatitis. TB, ALT and AST levels can predict the degree of liver enhancement in the hepatocyte phase of Gd-BOPTA-enhanced MRI.

Probiotic metabolites from Bacillus coagulans GanedenBC30^(TM) support maturation of antigen-presenting cells in vitro

AIM:To study the effects of probiotic metabolites on maturation stage of antigen-presenting immune cells.METHODS:Ganeden Bacillus coagulans 30(GBC30) bacterial cultures in log phase were used to isolate the secreted metabolite(MET) fraction.A second fraction was made to generate a crude cell-wall-enriched fraction,by centrifugation and lysis,followed by washing.A preparation of MET was subjected to size exclusion centrifugation,generating three fractions:< 3 kDa,3-30 kDa,and 30-200 kDa and activities were tested in comparison to crude MET and cell wall in primary cultures of human peripheral blood mononuclear cell(PBMC) as a source of antigen-presenting mononuclear phagocytes.The maturation status of mononuclear phagocytes was evaluated by staining with monoclonal antibodies towards CD14,CD16,CD80 and CD86 and analyzed by flow cytometry.RESULTS:Treatment of PBMC with MET supported maturation of mononuclear phagocytes toward both macrophage and dendritic cell phenotypes.The biological activity unique to the metabolites included a reduction of CD14+ CD16+ pro-inflammatory cells,and this property was associated with the high molecular weight metabolite fraction.Changes were also seen for the dendritic cell maturation markers CD80 and CD86.On CD14dim cells,an increase in both CD80 and CD86 expression was seen,in contrast to a selective increase in CD86 expression on CD14bright cells.The co-expression of CD80 and CD86 indicates effective antigen presentation to T cells and support of T helper cell differentiation.The selective expression of CD86 in the absence of CD80 points to a role in generating T regulatory cells.CONCLUSION:The data show that a primary mechanism of action of GBC30 metabolites involves support of more mature phenotypes of antigen-presenting cells,important for immunological decision-making.

Asymmetric Response of the South China Sea SST to El Nio and La Nia

The interannual variability of the sea surface temperature （SST） in the South China Sea （SCS） is investigated according to its relationship with E1 Nifio/La Nifia （EN/LN） using monthly products from ICOADS. The SCS SST bears two peaks associated with EN/LN and shows the asymmetric features. Coinciding with the mature phase of EN/LN, the first SST warming/cooling peaks in December（0）-February（1） （DJF（1）） and centers in the southern part. The major difference is in the amplitude associated with the strength of EN/LN. However, the SCS SST anomaly shows distinct difference after the mature phase of EN/LN. The EN SST warm- ing develops a mid-summer peak in June-August（1） （JJA（1）） and persists up to September-October（l）, with the same amplitude of the first warming peak. Whereas the LN SST cooling peaks in May（l）, it decays slowly until the end of the year, with amplitude much weaker. Comparing with SST and atmospheric circulations, the weak response and early termination of the second cooling is due to the failure of the cyclonic wind anomalies to develop in the northwest Pacific during JJA（1）.

Preparation and growth mechanism of plate-like basic magnesium carbonate by template-mediated/homogeneous precipitation method

In order to expand the application of the basic magnesium carbonate in the field of flame retardant,the plate-like basic magnesium carbonate(Mg5(CO3)4(OH)2.4H2O)was prepared successfully by template-mediated/homogeneous precipitation method,using magnesium chloride hexahydrate(MgCl2.6H2O)and urea(CO(NH2)2)as reaction materials.Phase and morphology of the product were characterized by X-ray diffraction(XRD),scanning electron microscope(SEM)and atomic force microscope(AFM),respectively.The results showed that well-crystallized plate-like Mg5(CO3)4(OH)2.4H2O can be prepared at the water bath temperature of 100°C,water bath time of 24 h,the aging time of 5 h after adding organic template agent.The investigation on organic template mediated mechanism shows that the template affects the crystal morphology by changing surface energy of different crystal plane.Through a preliminary study on the growth mechanism of the product,it is found that the generation of the plate-like Mg5(CO3)4(OH)2.4H2O could be explained by two-dimensional nucleation/step growth mechanism.

Diagenesis and porosity evolution of sandstone reservoirs in the East II part of Sulige gas field, Ordos Basin

It is becoming an important controlling factor of gas exploration and exploitation in the east part of Sulige gas field in the Ordos Basin where the reservoir of main gas formations is tight sandstones. Employing experimental methods of slice identification, casting slice, scan electron microscope, and X-ray diffrac- tions, we studied the characteristics of petrology and diagenesis on reservoirs in Shanl section of Shanxi formation and He8 section of Shihezi formation of the Permian system in the East II part of Sulige gas field. The results include： （1） the main sandstones in these areas are dominated by lithic sandstone and litbic silicarenite with low grade of maturity; （2） the diagenesis of sandstone in these areas mainly include compaction, cementation, corrosion and alteration. Conclusions are as follows： （1） the diagenetic stage reached period B of the middle diagenetic stage; （2） the early diagenetic compaction is one of the main factors to decreasing porosity; （3） the secondary pores formed by corrosion in acidity medium con- ditions in period A of the middle diagenetic stage can distinctly ameliorate the poor reservoir capability of sandstone and, （4） cementation in period B of the middle diagenetic stage is the most important factor leading; to poor physical property of sandstone reservoirs.

Sea surface temperature anomalies in the South China Sea during mature phase of ENSO

Based on the 18-year （1993-2010） National Centers for Environmental Prediction optimum interpolation sea surface temperature （SST） and simple ocean data assimilation datasets, this study investigated the patterns of the SST anomalies （SSTAs） that occurred in the South China Sea （SCS） during the mature phase of the E1 Nifio/Southem Oscillation. The most dominant characteristic was that of the out- of-phase variation between southwestern and northeastern parts of the SCS, which was influenced primarily by the net surface heat flux and by horizontal thermal advection. The negative SSTA in the northeastern SCS was caused mainly by the loss of heat to the atmosphere and because of the cold-water advection from the western Pacific through the Luzon Strait during E1 Nifio episodes. Conversely, it was found that the anomalous large-scale atmospheric circulation and weakened western boundary current during E1 Nifio episodes led to the development of the positive SSTA in the southwestern SCS.

Rock Weathering Tendency at Different Stages of Soil－Forming Processes in Fildes Peninsula， Antarctic

From the view of energy state of material, this paper introduces a concept of weathering potential in carrying out quantitative calculation of the relevant products at different stages of rock-weathering and primary soil-forming processes, elaborates respectively on weathering degree in the bio-weathering layer of rocks and during the formation of soil material and clay, and evaluats the further tendency of weathering in the above-mentioned stages. The authors have discovered that the scales of weathering potential of the materials increase successively in the three stages, which indicates that the products in the above-mentioned three stages must have undergone stronger and stronger weathering in the primitive forming process of soil in Fildes Peninsula, Antarctic. But, because of relatively weak chemical weathering, it is reasonable that there are much more skeleton grains and little clay in primary soils in this region. Meanwhile, the authors have also verified that the weathering potential of crude rock determines to some extent decrease in the products' weathering potential in the different stages in primary soil-forming, thereby plays an important role in the genesis and development of the primary soil in the studied area.

Physical simulation of hydrodynamic conditions in high rank coalbed methane reservoir formation

In order to select highly productive and enriched areas of high rank coalbed methane reservoirs, based on hydrologic geology as one of the main factors controlling coalbed methane （CBM） reservoir formations, the effect of hydrodynamic forces controlling CBM reservoir formations was studied by a physical simulation experiment in which we used CBM reservoir simulation facilities. The hydrodynamic conditions of high coal rank reservoirs in the Qinshui basin were analyzed. Our experiment shows the following results： under strong hydrodynamic alternating action, 6C~ of coalbed methane reservoir changed from the start at -2.95% ~ -3.66%, and the lightening process occurred in phases; the CI-I4 volume reduced from 96.35% to 12.42%; the CO2 vo- lume decreased from 0.75% in sample 1 to 0.68% in sample 2, then rose to 1.13% in sample 3; the N2 volume changed from 2.9% in sample 1 to 86.45% in sample 3. On one hand, these changes show the complexity of CBM reservoir formation; on the other hand, they indicate that strong hydrodynamic actions have an unfavorable impact on CBM reservoir formation. It was found that the gas volume and hydrodynamic intensity were negatively correlated and low hydrodynamic flow conditions might result in highly productive and enriched areas of high rank CBM.

An Estimation of the Diet of the Species Serranus Scriba （Linnaeus, 1758） in the Area of Nisiopi, in South-West Lesvos

The current study examines the diet of Serranus scriba （Osteichtyes of the family Serranidae）. This species of fish was collected using gillnets at the sea near the village of Sigri which is located in the South-West side of the island of Lesvos. Based on the results, Serranus scriba is characterized as carnivorous with a preference in Decapods. Also, the GSI （Gonado Somatic Index）, HSI （Hepato Somatic Index） and CF （Condition Factor） index were calculated, with the estimation of numbers of females and males and separation of mature stages using the scale Nikolsky. Majority of the individuals of this species are females with a ratio of 88% versus male with 12%. And based on the calculation of indicators they are characterized quite mature, with good percentage of stored energy and good condition of healthiness. Moreover, it is concluded, based on the above analysis, in the area there was plenty of food for the individuals of this species in their breeding season （April-August breeding season）.

Development of Weed Management Strategies for Cashew Cultivation in Ghana

Three field trials, one for establishment and two for mature phases respectively, were conducted to develop weed management strategies for cashew cultivation in Ghana. The treatments for the establishment phase consisted of hoe weeding of whole plot, hoe weeding of cashew lines and slashing of inter-rows, herbicide application with glyphosate of whole plot or cashew lines with slashing of inter-rows, relay cropping of the cashew plot with sorghum and a legume and intercropping with a legume. In one trial of the mature phase, the treatments were hoe weeding of whole plot two or three times a year, high slashing of whole plot three times a year, herbicide application （glyphosate） of whole plot and ring application of herbicide （glyphosate） plus high slashing of inter-rows twice a year. In the other trial, which was carried out on farmers＇ fields, glyphosate （Roundup） at 2.0 l/ha was tested against manual slashing. In the study of the establishment phase, neither the girth nor height of the cashew seedlings was significantly affected by the treatments. The first year and four year cumulative cashew yields were significantly affected by treatments with the intercrops giving higher yields than the glyphosate-treated plots. Intercropping as a weed control measure was generally more costly than glyphosate application or manual weeding. In the mature trials, chemical weed control slightly improved cashew nut yield and was cheaper to apply. It is recommended to adopt chemical weed control in cashew cultivation in Ghana.

Effect of Ripening Stages on Basic Deep-Fat Frying Qualities of Plantain Chips

Plantains （Musa paradisiaca L.） are a major food staple in West Africa and are cooked in various forms. The objective of this work was to evaluate the frying characteristics of plantains at different stages of ripening. The plantains used in the study were at the unripe stage through four different ripening stages. The samples were peeled and sliced into 2 mm thickness and blanched in hot water at 70 ℃ for 3 min. The slices were then deep flied in canola oil at 180 ℃. The result showed that ripening stage significantly affected moisture loss and fat absorption profiles of the plantain chips. Fully ripened plantain absorbed up to 34% （db） oil during 4 min frying, much higher than unripe plantain. The oil uptake and moisture loss during frying of the plantain chip samples were modelled using 1st order kinetics. The kinetic parameters including rates of moisture loss and oil uptake varied according to the different stages of ripening. Ripening had a significant effect on the colour lightness （L） of the chips. Similarly, the redness （a）, the yellowness （b） and textural characteristics were significantly affected by ripening stage.

Debt Rating Initiations： Natural Evolution or Opportunistic Behavior？

The authors examine a firm＇s decision to begin issuing debt in public bond markets and find that it is a function of both life cycle influences and opportunistic timing. Defining life cycle factors to encompass both a firm＇s age in years and its underlying characteristics, the authors confirm that bond market participation is generally restricted to large, mature firms. Summary statistics show that finns obtain their initial bond ratings on average 9.5 years after their equity initial public offering （IPO） and 11.8 years after initiating dividend payments. Growth rates, capital expenditures, and cash flow volatility all decline as the firm accesses public debt markets, consistent with entry into the mature phase of its life cycle. With respect to opportunistic timing, it is asked whether entry into public bond markets follows strong performance （or precedes weak performance） at both the firm and market levels. At the firm level, the authors find that the debt IPO occurs following periods of strong operating performance and high excess stock returns. At the market level, entry coincides with favorable interest rates and default spreads. The benefits of careful timing result in firms receiving initial bond ratings that are stronger than what would be predicted; however, there is no evidence of abnormal numbers of downgrades for these firms in subsequent years.

Pancreatic neuroendocrine neoplasms: Magnetic resonance imaging features according to grade and stage

AIMTo describe magnetic resonance (MR) imaging features of pancreatic neuroendocrine neoplasms (PanNENs) according to their grade and tumor-nodes-metastases stage by comparing them to histopathology and to determine the accuracy of MR imaging features in predicting their biological behavior.METHODSThis study was approved by our institutional review board; requirement for informed patient consent was waived due to the retrospective nature of the study. Preoperative MR examinations of 55 PanNEN patients (29 men, 26 women; mean age of 57.6 years, range 21-83 years) performed between June 2013 and December 2015 were reviewed. Qualitative and quantitative features were compared between tumor grades and stages determined by histopathological analysis.RESULTSIll defined margins were more common in G2-3 and stage III-IV PanNENs than in G1 and low-stage tumors (P < 0.001); this feature had high specificity in the identification of G2-3 and stage III-IV tumors (90.3% and 96%, 95%CI: 73.1-97.5 and 77.7-99.8). The mean apparent diffusion coefficient value was significantly lower in G2-3 and stage III-IV lesions compared to well differentiated and low-stage tumors (1.09 × 10-3 mm2/s vs 1.45 × 10-3 mm2/s and 1.10 × 10-3 mm2/s vs 1.53 × 10-3 mm2/s, P = 0.003 and 0.001). Receiving operator characteristic analysis determined optimal cut-offs of 1.21 and 1.28 × 10-3 mm2/s for the identification of G2-3 and stage III-IV tumors, with sensitivity and specificity values of 70.8/80.7% and 64.5/64% (95%CI: 48.7-86.6/60-92.7 and 45.4-80.2/42.6-81.3).CONCLUSIONMR features of PanNENs vary according to their grade of differentiation and their stage at diagnosis and could predict the biological behavior of these tumors.

The Puritan Culture and Entrepreneurial Education Idea in American Universities

The USA is one of the very developed countries with entrepreneurship education in colleges and universities.After more than half a century of development,it has reached a mature stage,and the formation of the concept of entrepreneurial education has advanced.In this paper, through the analysis of entrepreneurship education thought by Jeffrey Timmons as the representative of the America University entrepreneurship education idea, it finds out the Puritan culture factors,in order to better understand the basis and provides the reference of college enterprise education in China.

Geochemistry of solvable organic matter from source rocks in Shangkuli Formation of Labudalin Basin

A suit of lacustrine source rocks are developed in volcanic deposits in the Shangkuli Formation of the Cretaceous. However, it is poor to understand the characteristics of source rocks due to the low degree of exploration, thus the exploration is severely constrained in this area. Based on the geochemical analysis, the analytic technique of GC and GC-MS, combined with the characteristics of solvable organic matter and biomarkers of the source rocks, the authors discussed the depositional environment, the derivation of the matrix and the maturity characteristics of the organic material of the Shangkuli Formation in Cretaceous. The results show that the organic matter mainly belongs to type Ⅱ1 kerogen, whose abundance is relatively high; it was formed in reductive surrounding where was deep-lake; the hydrocarbon is characterized by mixed-source of organic matter. The thermal evolution of source rocks had reached maturation stage.

Studies on the community characteristics of major arthropods in summer maize fields

This study is to integrate pest management （IPM） of maize insect pest. The paper reports the current condition of species diversity of maize field in Nanning, Guangxi Province. All exper/mcntal materials were collected dur/ng the stages of tasseling, blister, milk, maturity and after reaping respectively from 5 plots from April to July, 2007. The Shannon-Wiener index（H）, Simpson index（H＇）, Brillouin index（J）, species evenness（E） and richness index （Dmc） were used into analysis of abundance and distribution characteristics of communities and populations of major arthropods in maize fields. Result showed that a total of 19 arthropods, belonged to 10 orders and 18 families, were obtained from maize fields. Of which there are 12 pest insects, 3 natural enemy insects, 2 spiders and 2 middle insects. All of the community diversity indices were the highest in maize fields after reaping. No significant difference was found between other 4 various stages i.t. tasseling, blister, milk and maturity stages. The results of this study will help to carry out the IPM of maize field pest insect.