bluuebunny/crossref_metadata_2025 huggingface dataset:
Producers' evaluation of an enhanced weather information service for the cotton industry in Australia
Authors: Anaman Kwabena A , Lellyett Stephen C
Published: June 2010

The study is concerned with producers' evaluation of an enhanced weather information service called the Cottonfields Weather Service produced by the Australian Bureau of Meteorology. The service has been in existence since the 1992/93 production year. It provides, at some cost to producers, the latest weather information for their locality, which is more detailed than the information obtained from the basic public weather service provided free of charge through the mass media. Access to the service is through a phone facsimile machine. The study involved a sample survey of 108 members of the Namoi Cotton Co‐operative, one of the largest cotton producing groups in Australia. Producers' assessment of the service was based on numerical scoring of key quality attributes of information for managerial decision making such as timeliness, ease of understanding, accuracy and overall usefulness. Results of the analysis indicated that about 51% of the members of the Co‐operative have adopted the service. Users generally considered the service to be of high quality, useful and effective. There was little variation in producers' assessment of various information quality attributes of the service. The level of formal education appeared to be the significant socio‐economic variable influencing the adoption of the service.
Severe weather in Mediterranean ports
Authors: Brand Sam , Englebretson Ronald , Gilmore Richard
Published: June 2010

Environmental phenomena such as strong winds, high waves, restrictions to visibility and thunderstorms can be hazardous to US Navy fleet operations. The Mediterranean region is an area where the complicated topography significantly influences these kind of environmental phenomena, particularly in the coastal regions. Because the US Navy recognised this as a concern to many ship captains, the Marine Meteorology Division of the Naval Research Laboratory, Monterey, California was asked to evaluate the severe weather suitability of 55 Mediterranean ports and document the results. The resulting analyses provide decision‐making guidance for ship captains as well as environmental information for operational forecasters. These port evaluations have been disseminated in hard copy form as individual port studies as well as in a compilation of all port studies in CD‐ROM format.
Sensitivity of trajectories to data resolution and its dependence on the starting point: In or outside a tropopause fold
Authors: Scheele M P , Siegmund P C , Van Velthoven P F J
Published: June 2010

Three‐dimensional ECMWF first‐guess wind fields at different horizontal (2.5° to 0.5°) and temporal (6h–3h) resolutions are used to investigate the sensitivity of five‐day backward trajectories, computed with the KNMI trajectory model, to the resolution of the wind data. This sensitivity, which is a measure for the accuracy of the computed trajectories, is investigated for two sets of trajectories: (a) a set starting in the small‐scale flow pattern of a tropopause fold occurring over De Bilt (52° N, 5° E) on 1 November 1994; (b) a set starting in the large‐scale flow outside this folding region. The sensitivity results for these two sets of trajectories show no significant differences. During the first two days the sensitivity to spatial and temporal data resolution is small for most of the trajectories, implying that for this period relatively reliable trajectories can be computed from relatively low‐resolution data for the situations considered in this study. After two days the sensitivity of many trajectories sharply increases, due to an extratropical cyclone that is encountered by these trajectories at that time.
Climatology of monthly and annual rainfall in Buenos Aires, Argentina
Authors: Penalba Olga C , Vargas Walter M
Published: June 2010

This paper examines the temporal and spatial variations of annual and monthly extreme precipitation for ten stations (1890–1980) in the central‐east of Argentina. Extremes of yearly and monthly rainfall are statistically defined. The time series of the annual and monthly rainfall anomalies are analysed. The dry years are concentrated in the beginning of the period of observation (before 1940) and the wet years are distributed throughout the whole period. The probability of having a wet or dry month is the same, and the probability of having two or more months with the same extreme condition is low. Harmonic analysis is applied to the monthly rainfall of the driest and wettest years to describe and analyse their different cycles. The annual cycle, for the driest years, tends to dominate over the whole region. The most important harmonic for the wettest years is the second one, associated with the advection of humidity.
The presentation of weather information via the media in Ethiopia
Authors: Sear C B , Tadesse T , Bettany B , Budgen P , Copley V , Griggs D
Published: June 2010

The Ethiopian National Meteorological Services Agency (NMSA) has been disseminating weather information and forecasts via the media since 1951. The quality and reach of the NMSA's broadcasts have improved markedly since 1993 after the installation by the Natural Resources Institute (NRI) of an NRI MEDIA System which combines ‘blue screen’ computer and video technologies in a low‐cost broadcasting package. The quality of Ethiopian weather forecasts and bulletins is now amongst the highest in Africa. Its success has raised the profile of the NMSA significantly. Recognising these benefits, the UK Meteorological Office (UKMO) has, under Voluntary Co‐operation Programme (VCP) funding, sponsored several other installations in Africa and elsewhere. In this paper we include a short history of Ethiopian weather broadcasts, discuss the present systems used and their national impact and outline the spread of similar services in other developing countries.
Thermal mapping: Reliability and repeatability
Authors: Shao J , Lister P J , Hart G D , Pearson H B
Published: June 2010

In winter road maintenance, accurate information as to the spatial variation in minimum road‐surface temperature is valuable for road authorities and organisations to decide where to target salting or gritting treatment. The process to record and quantify these patterns of temperature variation is called Thermal Mapping. The technique relies on the fact that the pattern of road‐surface temperature is reproduced from one night to the next similar night. This study establishes a valid statistical means of quantifying the similarity between temperature patterns captured during different Thermal Mapping surveys and is used to show that the Thermal Mapping process developed by the authors is reliable and that the pattern of temperature variation across a road network is reproduced under similar weather conditions.
Down syndrome risk calculation for a twin fetus taking account of the nuchal translucency in the co‐twin
Authors: Cuckle Howard , Maymon Ron
Published: June 2010

Objective

The objective of this study was to describe and illustrate a method for calculating fetus‐specific Down syndrome risk in twins, allowing for between‐fetus nuchal translucency (NT) correlation.

Methods

The between‐fetus correlation coefficient of log NT, in multiples of the median, was estimated from a series of 325 unaffected twins after adjustment for sonographer bias. A bivariate log Gaussian model was used to calculate likelihood ratios for discordant and concordant Down syndrome. Applying these to the prior maternal age‐specific risk yielded risks in monozygous and dizygous twins. The weighted average risk was then computed with weights relating to chorionicity, gender, assisted reproduction and ethnicity. The method was illustrated using examples.

Results

The correlation coefficient in unaffected pregnancies was 0.45 (P < 0.0001) and estimated to be 0.12 and 0.04 in discordant and concordant twins, respectively. The examples showed very large differences in the risks obtained when the extent of correlation in NT between fetuses is taken into account and when the measurements are treated as independent.

Conclusion

Fetus‐specific Down syndrome risks in twins should be calculated using its own NT value as well as that of the co‐twin. Copyright © 2010 John Wiley & Sons, Ltd.
The esophageal ‘pouch sign’: a benign transient finding
Authors: Solt Ido , Rotmensch Siegfried , Bronshtein Moshe
Published: June 2010

Objective

Sonographic finding of an esophageal pouch is considered pathognomonic for fetal esophageal atresia (EA). We investigated the clinical significance of this finding.

Methods

Longitudinal sonographic follow‐up in pregnancy and neonatal diagnostic work‐up was performed in six fetuses with an esophageal neck pouch referred for polyhydramnios and a small or absent stomach. Fetal swallowing and cyclic distension of the pouch were observed for at least 30 min, and follow‐up examinations were conducted at 2 to 3 weeks intervals.

Results

First visualization of the pouch occurred between 18 and 29 weeks of gestation. All pouches were located above the fetal clavicle. No additional anomalies were detected on detailed anatomic survey. Five fetuses had normal karyotypes. At 21 to 33 weeks of gestation, polyhydramnios had resolved, and the stomach was found to be normal in size and shape in all cases. The neonatal work‐up ruled out EA in all cases.

Conclusion

The fetal esophageal pouch sign occurs in structurally normal fetuses and should not be considered pathognomonic for EA or serve as the grounds for pregnancy termination. Copyright © 2010 John Wiley & Sons, Ltd.
A comparative study of thermotropic LCP and organoclay as fillers in high molecular mass polyethylene with different blending sequences
Authors: Tang Youhong , Gao Ping , Ye Lin , Zhao Chengbi
Published: June 2010

The influences of thermotropic liquid crystalline copolyester (TLCP) on viscosity reduction in high molecular mass polyethylene (HMMPE) filled with organoclay were investigated by controlling the blending sequence. The interactions between organoclay and TLCP in HMMPE create different morphologies and influence rheological properties of the clay/TLCP/HMMPE blends. When the organoclay was blended with TLCP first, large amounts of organoclay formed partially intercalated structures in TLCP, with phase separation occurring at the temperature when TLCP was in the nematic phase, corresponding an antagonistic effect which weakens viscosity reduction ability of TLCP for HMMPE. However, with first blending of TLCP with HMMPE and then adding organoclay into the blend, most of the organoclay enriched on TLCP surfaces in the blend. Such interaction prevents TLCP droplets from coalescing at high shear stresses, enlarging the processing window. A phenomenological model, originally for HMMPE/TLCP systems, was successfully adopted to predict the flow behaviors of clay/HMMPE/TLCP blends. POLYM. ENG. SCI., 50:1679–1688, 2010. © 2010 Society of Plastics Engineers
Preparation and characterization of nanoclay‐filled polyurethane/polypropylene blends
Authors: Kannan M. , Bhagawan S.S. , Jose Tomlal , Thomas Sabu , Joseph Kuruvilla
Published: June 2010

Ester‐based thermoplastic polyurethane (TPU) nanocomposites were prepared by melt blending at 190°C, using 3 wt% Cloisite 10A (organically modified montmorillonite clay) as the nanoscale reinforcement [TPU(C10A)]. The nanocomposites were subsequently melt‐blended with polypropylene (PP) using maleic anhydride–grafted polypropylene (MA‐g‐PP) as a compatibilizer [in the ratio of 70/30‐TPU/PP, 70/25/5‐TPU/PP/MA‐g‐PP, 70/25/5‐TPU (C10A)/PP/MA‐g‐PP]. Besides giving substantial increase in modulus, tensile strength, and other properties, organoclay reinforcement functions as a surface modifier for TPU hard segment resulting in improved dispersion. The morphology and other characteristics of the nanocomposite blends were investigated in terms of X‐ray diffraction, fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical analysis, tensile properties, scanning electron microscopy, and atomic force microscopy. The results indicate that the ester‐TPU(C10A)/PP/MA‐g‐PP exhibited better dispersion than other blend systems; abrasion resistance and water absorption resistance were also better for this system. POLYM. ENG. SCI., 50:1878–1886, 2010. © 2010 Society of Plastics Engineers
Numerical modeling of nonisothermal polymer crystallization kinetics: Flow and thermal effects
Authors: Zinet Matthieu , El Otmani Rabie , Boutaous M'hamed , Chantrenne Patrice
Published: June 2010

A numerical model able to simulate polymer crystallization under nonisothermal flows is developed. It is based on the assumption that the trace of the extra‐stress tensor, calculated according to a viscoelastic multimode Upper Convected Maxwell (UCM) model, is the driving force of the flow‐induced extra nucleation. Two distinct sets of Schneider equations are used to describe the growth of thermally and flow induced nuclei. The model is then coupled with the momentum equations and the energy equation. As an application, a shear flow configuration between two plates (Couette flow) is simulated. The relative influence of the mechanical and thermal phenomena on the crystallization development as well as the final morphology distribution is then analyzed as a function of the shearing intensity and the cooling kinetics, in terms of nucleation density and crystallite mean sizes. POLYM. ENG. SCI., 50:2044–2059, 2010. © 2010 Society of Plastics Engineers
Solid‐state microcellular polycarbonate foams. I. The steady‐state process space using subcritical carbon dioxide
Authors: Weller John E. , Kumar Vipin
Published: June 2010

The process parameters for production of solid‐state microcellular polycarbonate using subcritical CO2 were explored. Sufficiently long foaming times were used to produce foams, where cell growth had completed, resulting in steady‐state structures. A wide range of foaming temperatures and saturation pressures below the critical pressure of CO2 were investigated, establishing the steady state process space for this polymer–gas system. Processing conditions are presented that produce polycarbonate foams where both the foam density and the average cell size can be controlled. The process space showed that we could produce foams at a constant density, while varying the cell size by and order of magnitude. At a relative density of 0.5, the average cell size could be varied from 4 to 40 μm. The ability to produce such a family of foams opens the possibility to explore the effect of microstructure, like cell size on the properties of cellular materials. It was found that the minimum foaming temperature for a given concentration of CO2, determined from the process space, agrees well with the predicted glass transition temperature of the gas–polymer solution. A characterization of the average cell size, cell size distribution, and cell nucleation density for this system is also reported. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
Evaluating contrast gloss of textured polymeric surfaces
Authors: Ignell Sofie , Kleist Ulf , Rigdahl Mikael
Published: June 2010

The concept of contrast gloss and its relation to visually perceived gloss was examined for textured polymeric specimens. The specimens were injection‐molded plaques manufactured in three different polymers (acrylonitrile‐butadiene‐styrene copolymer, polypropylene, and a blend of polycarbonate and acrylonitrile‐butadiene‐styrene copolymer). A contrast gloss factor was determined from the reflectance data obtained with a conventional multiangle spectrophotometer. To evaluate the visual impression of gloss of the specimens a psychometric study was performed. The contrast gloss factor corresponded well with the visual assessment of the gloss and it was able to discern the visual differences between several specimens not significantly discriminated by their gloss values. These latter gloss values were obtained with a conventional glossmeter measuring specular gloss. In correspondence with the visual assessments and practical experience, the relation between the contrast gloss factor and the specular glossmeter measurements was found to depend on the type of polymer used. When evaluating gloss of specimens varying in color, the contrast gloss factor corresponded well with the visual assessments. This was in contrast to the specular glossmeter measurements which ranked the specimens essentially in the opposite order. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
Study on the packing effects of external gas‐assisted injection molding on part shrinkage in comparison with conventional injection molding
Authors: Chen Shia‐Chung , Lin Yi‐Chang , Huang Sung‐Wei
Published: June 2010

Applying gas pressure on the reverse side of the part that called external gas‐assisted injection molding (EGAIM) has the potential to solve shrinkage‐related molding problems. We investigate the packing effects of EGAIM on part shrinkage and sink mark under various rib design and compare it to that of conventional injection molding (CIM). It was found that EGAIM has uniformly distributed packing pressure within the entire mold cavity. To achieve equivalent part shrinkage, CIM requires 100 MPa packing pressure from the molding machine, whereas EGAIM requires only 9 MPa. EGAIM can further reduce part shrinkage if the gas pressure and gas packing time are both increased. EGAIM can also eliminate sink marks for rib designs of an aspect ratio (rib width /part thickness) up to 1.2, whereas CIM can achieve the same sink mark level only at an aspect ratio of less than 0.5. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
Acute lower respiratory tract infections by human metapneumovirus in children in Southwest China: A 2‐year study
Authors: Chen Xin , Zhang Zhi Yong , Zhao Yao , Liu En Mei , Zhao Xiao Dong
Published: June 2010

Human metapneumovirus (hMPV) has been reported to cause both upper and lower respiratory tract diseases in susceptible populations, particularly in children and the elderly. In this study, we describe a hospital‐based epidemiological study of hMPV in patients presenting to a children's hospital and show the demographic and clinical characteristics associated with hMPV infection in China, retrospectively. Specimens were collected over a 2‐year period from children hospitalized with acute lower respiratory tract infections (ALRTI) and analyzed for the presence of hMPV using real‐time RT‐PCR assays. The presence of hMPV was detected in 227 (25.9%) of the 878 children studied and may circulate year‐round in the area, peaking during the winter–spring season. Younger children (aged less than 6 months) had the highest positive rate. Infections by hMPV showed similar epidemiology and clinical manifestations as for respiratory syncytial virus (RSV) and were found in high co‐infections with RSV. Subgroup A2 hMPV was the most predominant genotype identified during the study period. This study indicates that hMPV is one of the major respiratory pathogens found in children in southwest China and vaccine development should be under consideration. Pediatr. Pulmonol. 2010; 45:824–831. © 2010 Wiley‐Liss, Inc.
Dornase alfa improves the health‐related quality of life among Brazilian patients with cystic fibrosis—A one‐year prospective study
Authors: Rozov Tatiana , de Oliveira Viviane Ziebell , Santana Maria Angélica , Adde Fabíola Villac , Mendes Rita Heloisa , Paschoal Ilma Aparecida , Caldeira Reis Francisco J. , Higa Laurinda Yoko Shinzato , Toledo Antonio Carlos de Castro , Pahl Márcia ,   the Pulmozyme Study Group
Published: June 2010

Background

Health‐related quality of life (HRQOL) measurements provide valuable information about the psychological and social impact of treatment on patients with cystic fibrosis (CF). This study evaluated the HRQOL of Brazilian patients with CF and assessed the changes in HRQOL domains over 1 year after dornase alfa (Pulmozyme) introduction.

Patients and Methods

One hundred fifty‐six stable patients with CF and 89 caregivers answered the Portuguese‐validated version of the Cystic Fibrosis Questionnaire‐Revised (CFQ‐R) at baseline (T0), and at 3 (T1), 6 (T2), 9 (T3), and 12 (T4) months of follow‐up. Eighteen patients were excluded because they did not fulfill the inclusion criteria. The patients were analyzed in two groups: those aged 6–11 years and those aged 14 years and older. ANOVA for observed repeated results and the last observation carried forward (LOCF) method for missing data were used for the statistical analysis.

Results

After 1 year of follow‐up, there was significant improvement in respiratory symptoms (T4 − T0 = 8.1; 95% confidence interval (95% CI) = [2.1;14.0]; effect size (ES) = 0.35; P < 0.001), Emotional Functioning (T4 − T0 = 5.6; 95% CI = [1.1;10.1]; ES = 0.31; P < 0.05), Social Functioning (T4 − T0 = 6.0; 95% CI = [1.3;11.7]; ES = 0.31; P < 0.05), Body Image (T4 − T0 = 11.9; 95% CI = [4.1;19.7]; ES = 0.42; P < 0.05), and Treatment Burden (T4 − T0 = 5.3; 95% CI = [0.3;10.3]; ES = 0.24; P < 0.05) domains in the younger group. A significant improvement in Role Functioning (T4 − T0 = 6.1; 95% CI = [1.1;11.1]; ES = 0.40; P < 0.05), Body Image (T4 − T0 = 12.6; 95% CI = [3.5;21.7]; ES = 0.46; P < 0.05), and Weight (T4 − T0 = 11.7; 95% CI = [1.8;21.6]; ES = 0.40; P < 0.05) was obtained in the older group. The caregivers' CFQ‐R showed improvements in the Digestive Symptoms (T4 − T0 = 5.5; 95% CI = [1.5;9.4]; ES = 0.30; P < 0.05), Respiratory Symptoms (T4 − T0 = 7.6; 95% CI = [3.9;11.4]; ES = 0.48; P < 0.05), and Weight (T4 − T0 = 10.1; 95% CI = [1.6;18.6]; ES = 0.26; P < 0.05) domains.

Conclusion

The introduction of dornase alfa improved the HRQL of the patients with CF during the first year of treatment. Pediatr. Pulmonol. 2010; 45:874–882. © 2010 Wiley‐Liss, Inc.
Expression of cancer/testis antigens in prostate cancer is associated with disease progression
Authors: Suyama Takahito , Shiraishi Takumi , Zeng Yu , Yu Wayne , Parekh Nehal , Vessella Robert L. , Luo Jun , Getzenberg Robert H. , Kulkarni Prakash
Published: June 2010

BACKGROUND

The cancer/testis antigens (CTAs) are a unique group of proteins normally expressed in germ cells but aberrantly expressed in several types of cancers including prostate cancer (PCa). However, their role in PCa has not been fully explored.

METHODS

CTA expression profiling in PCa samples and cell lines was done utilizing a custom microarray that contained probes for two‐thirds of all CTAs. The data were validated by quantitative PCR (Q‐PCR). Functional studies were carried out by silencing gene expression with siRNA. DNA methylation was determined by methylation‐specific PCR.

RESULTS

A majority of CTAs expressed in PCa are located on the X chromosome (CT‐X antigens). Several CT‐X antigens from the MAGEA/CSAG subfamilies are coordinately upregulated in castrate‐resistant prostate cancer (CRPC) but not in primary PCa. In contrast, PAGE4 is highly upregulated in primary PCa but is virtually silent in CRPC. Further, there was good correlation between the extent of promoter DNA methylation and CTA expression. Finally, silencing the expression of MAGEA2 the most highly upregulated member, significantly impaired proliferation of prostate cancer cells while increasing their chemosensitivity.

CONCLUSIONS

Considered together, the remarkable stage‐specific expression patterns of the CT‐X antigens strongly suggests that these CTAs may serve as unique biomarkers that could potentially be used to distinguish men with aggressive disease who need treatment from men with indolent disease not requiring immediate intervention. The data also suggest that the CT‐X antigens may be novel therapeutic targets for CRPC for which there are currently no effective therapeutics. Prostate 70: 1778–1787, 2010. © 2010 Wiley‐Liss, Inc.
Expression analysis of putative stem cell markers in human benign and malignant prostate
Authors: Ugolkov Andrey V. , Eisengart Laurie J. , Luan Chunyan , Yang Ximing J.
Published: June 2010

BACKGROUND

Stem cells were suggested to be present in human prostate cancer as a small population of distinct cells, which may contribute to carcinogenesis, tumor recurrence, and chemoresistance. To identify potential prostatic stem cells, we analyzed the expression of several potential stem cell markers in benign prostate and prostatic adenocarcinoma.

METHODS

CD44, CD133, Oct4, SOX2, and EZH2 expression was detected by immunohistochemical (IHC) staining using tissue microarray assays (TMA) composed of benign (non‐neoplastic) prostatic tissue, high grade prostatic intraepithelial neoplasia (HGPIN), and prostatic adenocarcinoma. Positive staining was defined as 1+ (<10%), 2+ (10–50%), or 3+ (>50%).

RESULTS

We found CD44 staining in 97% and 72% of benign + HGPIN and malignant lesions, respectively. CD133 staining was detected in a small fraction (4 of 67) of prostate carcinomas. We found that Oct4 nuclear expression was strongly associated with benign lesions and HGPIN but not prostate cancer (P < 0.05). In most cases, nuclear expression of EZH2 and SOX2 was detected in less than 10% of cells in non‐neoplastic prostate glands, HGPINs or prostate adenocarcinomas. Moreover, 27 of 33 SOX2 1+ prostate cancers were also EZH2 1+, whereas all 33 of these cases were CD44+.

CONCLUSIONS

Expression of CD44 and Oct4 identified large populations of benign and malignant cells in the prostate, which did not fit the definition of stem cells as a small fraction of the total cell population. Our results suggest that combined expression of embryonic stem cell markers EZH2 and SOX2 might identify potential cancer stem cells as a minor (<10%) subgroup in CD44+ prostatic adenocarcinoma. Prostate 71: 18–25, 2011. © 2010 Wiley‐Liss, Inc.
Serum Mac‐2BP does not distinguish men with high grade, large volume prostate cancer from men with benign prostatic hyperplasia
Authors: Peehl Donna M. , Chen Zuxiong , Nolley Rosalie
Published: June 2010

BACKGROUND

Mac‐2 binding protein (Mac‐2BP) is a secreted protein that has been used as a serum prognostic marker for several types of cancers. A previous study showed that serum Mac‐2BP was significantly higher (∼2‐fold) in men with prostate cancer compared to healthy men. We investigated whether serum Mac‐2BP could distinguish men with high grade, large volume prostate cancer from men with benign prostatic hyperplasia (BPH).

METHODS

A commercially available ELISA kit was used to measure Mac‐2BP in paired pre‐ and post‐prostatectomy sera from 10 men with high grade, large volume prostate cancer, in pre‐operative sera from 50 untreated men with high grade, large volume prostate cancer, and in sera from 50 men with clinical symptoms of BPH and biopsy‐negative for prostate cancer. Results were analyzed by Student's t‐test and receiver operating characteristic (ROC) curves.

RESULTS

Levels of Mac‐2BP did not decrease in post‐prostatectomy sera, and Mac‐2BP values were not significantly different in the sera of men with prostate cancer versus those with BPH.

CONCLUSION

Serum Mac‐2BP does not appear to originate in the prostate and it is unlikely that Mac‐2BP can be used for the differential diagnosis of prostate cancer versus BPH. Prostate 71: 26–31, 2011. © 2010 Wiley‐Liss, Inc.
Homology modelling of Drosophila cytochrome P450 enzymes associated with insecticide resistance
Authors: Jones Robert T , Bakker Saskia E , Stone Deborah , Shuttleworth Sally N , Boundy Sam , McCart Caroline , Daborn Phillip J , ffrench‐Constant Richard H , van den Elsen Jean MH
Published: June 2010

BACKGROUND: Overexpression of the cytochrome P450 gene Cyp6g1 confers resistance against DDT and a broad range of other insecticides in Drosophila melanogaster Meig. In the absence of crystal structures of CYP6G1 or complexes with its substrates, structural studies rely on homology modelling and ligand docking to understand P450–substrate interactions.

RESULTS: Homology models are presented for CYP6G1, a P450 associated with resistance to DDT and neonicotinoids, and two other enzymes associated with insecticide resistance in D. melanogaster, CYP12D1 and CYP6A2. The models are based on a template of the X‐ray structure of the phylogenetically related human CYP3A4, which is known for its broad substrate specificity. The model of CYP6G1 has a much smaller active site cavity than the template. The cavity is also ‘V’‐shaped and is lined with hydrophobic residues, showing high shape and chemical complementarity with the molecular characteristics of DDT. Comparison of the DDT–CYP6G1 complex and a non‐resistant CYP6A2 homology model implies that tight‐fit recognition of this insecticide is important in CYP6G1. The active site can accommodate differently shaped substrates ranging from imidacloprid to malathion but not the pyrethroids permethrin and cyfluthrin.

CONCLUSION: The CYP6G1, CYP12D1 and CYP6A2 homology models can provide a structural insight into insecticide resistance in flies overexpressing P450 enzymes with broad substrate specificities. Copyright © 2010 Society of Chemical Industry
Process of epitaxial crystal growth for CaSO4 · 0.5H2O on a surface of dissolving fluorapatite crystals studied by scanning electron microscopy
Authors: Dorozhkin S. V.
Published: June 2010

A process for the epitaxial crystal growth for CaSO4· 0.5H2O on a surface of dissolving natural fluorapatite (FAP) crystals under conditions of wet‐process phosphoric acid production has been studied by scanning electron microscopy (SEM). With the SEM working in a secondary electron mode, we were able to establish the main stages of the coating formation, including direct measurements of its thickness and growing rate values for individual needle‐like CaSO4· 0.5H2O crystals. Confirmation of an aggregate mechanism for CaSO4· 0.5H2O epitaxial crystals growth, established earlier under conditions of chemical crystallization, was achieved for the first time. The mechanism includes the following steps: (1) ultramicrocrystals of CaSO4· 0.5H2O were formed, (2) they coalesced into needle‐like crystals by means of mutual aggregation, (3) the needle‐like crystals united into star‐like and besom‐like aggregates, and (4) the latter formed macro‐aggregates. We have found that these steps occur simultaneously, resulting in multilayer coating formation. During the investigation, the phenomenon of FAP crystals aggregation by means of mutual intergrowing of epitaxial CaSO4· 0.5H2O coatings and the peculiarities of the etching process for the FAP crystal surface under conditions of CaSO4· 0.5H2O coatings formation were also studied.
Observation of the retina using the tandem scanning confocal microscope
Authors: Mathers William , Littlefield Timothy , Lakes Roderic , Lane James A. , Daley Thomas E.
Published: June 2010

A tandem scanning confocal microscope (TSCM) is currently being used to obtain high‐resolution images of the human cornea in vivo. Advantages of confocal microscopy for in vivo imaging include optical sectioning and increased contrast through removal of scattered light. We have adapted the TSCM to view the retina in vivo by constructing an applanating lens and fitting the microscope with an imaging‐intensifying camera of increased sensitivity. The microscope uses a spinning disc with 40,000 holes, each of 30 microns diameter, and a 100 W mercury arc lamp light source with a 455 nm long pass filter. The applanating lens is composed of three elements, two of which are movable for focusing. Images of a rabbit retina were obtained in vivo revealing the nerve fiber layer and blood vessels around the optic disc. The power density at the retina was calculated to be 3 mW/cm2, which is well below the power levels of a direct or indirect ophthalmoscope. Magnification of the retinal image was approximately 60x and a 1 mm wide area of retina was in view. This prototype TSCM system demonstrates that images of a retina in vivo are obtainable with confocal microscopy and that the sharpness is comparable to standard fundus camera photography. Further modifications to improve the light level and alterations in the design of the objective should improve the quality of the images obtained and achieve the enhanced resolution of which, in theory, the confocal microscope is capable.
The mechanisms of formation of ohmic contacts to AlGaAs: A microstructural, elemental diffusion and electrical investigation
Authors: Cole M. W. , Han W. Y. , Casas L. M. , Eckart D. W. , Monahan T. , Jones K. A.
Published: June 2010

Interfacial microstructure and phase composition of PtTiGePd ohmic contacts to heavily C‐doped AlGaAs were investigated as a function of annealing temperatures. Results of the material analyses were used to explain the specific contact resistances measured for each thermal treatment. Evidence of interdiffusion and compound formation between AlGaAs and Pd was visible in a Ga‐rich Pd‐Ga‐As reaction zone prior to heat treatment. As the annealing temperature was raised from 530 to 600°C, As began to out‐diffuse. At 600°C, this As out‐diffusion, which is critical to the formation of good p‐type ohmic contacts, contributed to the creation and development of the laterally continous two‐phase interfacial region, TiAs/Pd12Ga2Ge5, overlying the AlGaAs substrate. The minimum specific contact resistance was also achieved at this temperature. As the annealing temperature was elevated to 650°C, the specific contact resistance degraded in response to intensive chemical diffusion and development of a broad, nonuniform multiphased interfacial region.
Multiphase analysis of Bi‐Sr‐Ca‐Cu‐O high Tc superconductors with x‐ray compositional mapping
Authors: Marinenko R. B. , Bright D. S. , Bernik S.
Published: June 2010

Ba‐Sr‐Ca‐Cu‐O (BSCCO) high Tc superconductor specimens were prepared as part of a solid‐solubility study in the region of the 2223 phase. The identification and determination of the amount of each phase in the final products were necessary. Quantitative digital x‐ray compositional mapping with the electron microprobe was done with five wavelength spectrometers, one for each of the cations. To facilitate phase identification and quantification, image processing rules were developed for the nine possible phases, with each assigned a unique color. Using this procedure, at least six different phases were identified. Examples are cited in color.
Angular‐dependent energy distributions for backscattered electrons—Calculation of the surface ionization
Authors: Andrae M. , Rührbacher K. , Klein P. , Rnisch J. W.
Published: June 2010

An equation for angular‐dependent energy distributions of backscattered electrons is presented. Extensive Monte Carlo simulations lead to a simple description for the energy distribution. A comparison of the new expression with experimentally derived curves, Monte Carlo results, and an analytical model is performed. The newly derived energy distributions are used for the calculation of the surface ionization ϕ0 for oblique angle of incidence. For normal incidence, a comparison with several published experimental data leads to a mean value for the deviation of < 4%. For tilted specimens the results are compared with findings of other authors.
New expressions for angular distributions
Authors: Klein P. , Andrae M. , Röhrbacher K. , Wernisch J.
Published: June 2010

An electron scattering model (multiple reflections) based on physical quantities only is refined and extended. New expressions for the most probable scattering angle, for the angular distribution of transmitted electrons, and for the angular distribution of backscattered electrons under oblique incidence, derived by fitting to already published data or to Monte Carlo results, are presented and compared with well‐established formulae. The mean path‐elongation factor for a multiple reflection model is calculated by introducing a correlation of angular distributions. The value of the new path elongation factor is compared with already existing fits.
A computer program to illustrate macro topography on electron backscattering
Authors: Howell P. G. T.
Published: June 2010

This paper describes a computer program which enables the trajectories of an electron to be followed inside a solid sample and its pathway if it is successful to exit the sample's surface, and to be considered a backscattered electron (BSE). The simulation aids to understand the backscattering process and the effect of the sample that has other than an ideal flat surface topography. Several types of surface for the sample are simulated: a flat surface which can be tilted, a rough surface represented by a sine wave, and a circular surface to represent filamentous structures. The target material is entered as its empirical formula so that its mean atomic number may be calculated. It is covered with a layer of conductive coating, and it may be structured with vertical or horizontal layers of a second‐phase material. Where appropriate, the position of the electron beam impacting on the target may be moved in relation to the underlying structures. The passage of the electron through the substrate is displayed on the computer monitor in high‐resolution graphics. Information about those electrons which return to the sample surface and are backscattered is stored for later analysis. The paths of these BSEs are replotted to show the volume of the sample from which the image‐forming data are derived. Further graphic output provides histograms of the energy distribution and of the BSEs exit direction.
Vascular regression during amphibian metamorphosis—A scanning electron microscope study of vascular corrosion casts of the ventral velum in tadpoles of Xenopus laevis Daudin
Authors: Aichhorn Heidi , Lametschwandtner Alois
Published: June 2010

We used scanning electron microscopy and vascular casting to study gross arterial supply, venous drainage, and microvascular patterns of the fully developed ventral velum of tadpoles of Xenopus laevis Daudin and analyzed changes of the velar vascular bed from prometamorphosis to metamorphic climax in a qualitative and quantitative manner. The multilayered, highly secretory ventral velum is supplied bilaterally by an anterior and a posterior velar artery, branches of the external carotid artery. Velar arterioles branch mainly dichotomously and form a flat two‐dimensional capillary meshwork overlying the tops of filterplates I‐IV. Thymopharyngeal veins, dorsal branches of the filter plates veins, and the internal jugular veins drain the velum toward the venous sinus of the heart. Location, architecture, and the drainage of the velar microvascular bed into the venous sinus make a significant contribution of the velar capillaries to gas exchange unlikely. Instead, velar capillaries rather serve the nutrition of the secretory epithelium. The overall morphology of velar vessels from prometamorphosis to metamorphic climax—deduced from vascular corrosion casts—points to atonic vessels with increased leakage indicated by adhering globular extravasations, and to obstructed or blind ending vessels evidenced by the tapered and/or rounded blind ending cast vessels. The significant decrease in the size of the ventral velum during the metamorphic cycle was paralleled by a miniaturization of the velar vascular bed. We hypothetize that this miniaturization occurs by a shortening and fusion of capillary mesh elements. Our findings in corrosion casts, particularly the miniaturization of the velar microvascular bed and the morphology of the regressing capillaries, point to profound morphologic and ultrastructural changes in velar vessels; a study on the fine structure of the microvascular bed of the ventral velum in metamorphic tadpoles is in progress.
Imaging deep holes in structures with gaseous secondary electron detection in the environmental scanning electron microscope
Authors: Newbury Dale E.
Published: June 2010

The gaseous secondary electron detector (GSED) in the environmental scanning electron microscope (ESEM) permits collection of electron signals from deep inside blind holes in both conducting and insulating materials. The placement of the GSED as the final pressure‐limiting aperture of the ESEM creates a situation of apparent illumination along the line of sight of the observer. In principle, any point struck by the primary beam can be imaged. Image quality depends on the depth of the hole. In brass, features at the bottom of a 1.5 mm diameter hole that was 8 mm deep were successfully imaged.
A new method for low‐magnification in the environmental scanning electron microscope
Authors: Taylor M. E. , Wight S. A.
Published: June 2010

A device has been developed and used successfully on two models of the environmental scanning electron microscope that allows low‐magnification imaging of about 30x, significantly better than the original 200x low‐magnification imaging limit. This was achieved by using an additional aperture to limit the pressure at a point where it will not block the electron beam, and a larger aperture plate for the combination final aperture/secondary electron signal collection surface that also does not block the electron beam significantly.
Environmental scanning electron microscope observations of H2S attack on the protective oxide on an Ni‐Fe alloy
Authors: Pirttiaho Lauuri , Blakely Jack
Published: June 2010

Protective oxide layers on metals are frequently attacked by corroding agents. In this study, the attack of H2S on the protective oxide on 60 wt‐%Ni‐40 wt‐%Fe was studied. The oxide layer was prepared in a UHV system and the sulphidation was done in an environmental scanning electron microscope at an elevated temperature. The single crystal Ni‐Fe sample had a (100) surface which was oxidized by O2 exposure at about 800 K to produce an epitaxial Fe2O3 film. The breakup of the oxide was found to begin by pitting along surface features which are believed to correspond to atomic steps or step bunches. The areas where the oxide was more uniform were found to show better resistance toward the sulphidation.
Investigation of cholesterol, bilirubin, and protein distribution in human gallstones by color cathodoluminescence scanning electron microscopy and transmission electron microscopy
Authors: Loginov A. S. , Chebanov S. M. , Petrakov A. V. , Saparin G. V. , Obyden S. K. , Ivannikov P. V.
Published: June 2010

The application of color cathodoluminescent scanning electron microscopy (CCL‐SEM) for qualitative luminescence analysis of cholesterol, bilirubin, and protein in human gallstones was demonstrated. Images of these deposits (cholesterol, bilirubin, and protein) were formed in real colors (blue—cholesterol, red, orange—bilirubin, yellow, green—protein) in accordance with the cathodoluminescent spectrum for each control material. The other method described for transmission electron microscopy (TEM) of ultra‐thin sections provides more detailed characterization of the ultrastructure of cholesterol‐containing regions and their spatial interrelations with bilirubin‐containing regions. Using CCL‐SEM combined with TEM permits the receipt of more complete information about the chemical composition and ultrastructure of gallstones and may lead to more effective understanding of the pathogenesis of cholesterol cholelithiasis.
Changes in the microstructural and electrical behavior of poly‐Si films subjected to ion implantation and annealing process modifications
Authors: Cole M. W.
Published: June 2010

Polycrystalline silicon (poly‐Si) films implanted with arsenic using beam currents of 500 μA (400°C) and 230 μA (room temperature) have been investigated via transmission electron microscopy (TEM), secondary ion mass spectrometry (SIMS), and spreading resistance analysis (SRA). Experimental observations demonstrated the annealed high beam current‐implanted poly‐Si to possess inferior electrical properties compared with that implanted at a lower beam current. The reduced electrical activity of the high beam current‐versus the low beam current‐implanted poly‐Si was directly related to the postimplant microstructure (small grains ∼140 nmvs. amorphous) and the mechanism of the subsequent anneal (grain growth vs. recrystallization). The recrystallization mechanism augmented the electrical activation of the As dopant (decreased sheet resistivity) via a reduction of total grain boundary area. Further improvement in the electrical performance of the low beam current‐implanted poly‐Si, a resistivity decrease of up to 28%, was incurred via a two‐step annealing process. This process induced grain growth, which in turn minimized total grain boundary area and dopant trapping.
Monte Carlo simulation of electron backscattering from compounds with low mean atomic number
Authors: Howell P. G. T. , Boyde A.
Published: June 2010

This paper reports a Monte Carlo simulation where a single atom scattering model is adopted. The element taking part in each electron‐atom interaction is selected on the basis of its contribution eitherto the total elastic cross section or to the electron's mean free path. Both Rutherford and Mott scattering are considered, with the continuous slowing down process of Bethe used to calculate the energy loss to the system. The backscattered electron coefficients show good agreement with experimental results from a large group of low atomic number materials when using a model which selects the scattering atom by its contribution to the whole compound calculated from its atomic fraction of the total elastic cross‐section.
Particle development in apple juice determined by light scattering and electron microscopy
Authors: Beveridge T. , Harrison J. H. , Dalgleish D. G.
Published: June 2010

Light scattering was used to detect the kinetic development of particles in apple juices produced with and without oxidation and in procyanidin extracts prepared from these two juices. Particle size developed exponentially inboth oxidized and unoxidized juices, suggesting an enzymatic origin for the particle forming reactions. The procyanidin extract from oxidized juices produced particles which grew linearly, suggesting diffusion‐controlled aggregation or coalescence of particles. Procyanidins from unoxidized juice showed no particle development over at least 60 days of storage. Electron microscopy showed particles similar to those seen previously and some newly described morphologies. The mechanism of haze particle development is discussed in the light of the light scattering and electron microscopic results.
Reproducibility and accuracy of spatial measurements from digitally captured images in the environmental scanning electron microscope
Authors: Cousens D. R. , Kinaev N. N. , Ranasinghe M.
Published: June 2010

Accurate spatial measurements in a scanning electron microscope (SEM) require calibration of the magnification as a function of working distance and microscope operating conditions. This work presents the results of the calibration of an environmental SEM for the accurate spatial measurement of dimensions and areas in experiments, both for the measurement of strain in steel specimens under applied loads and the measurement of dimensional changes in timber with changes in relative humidity.
Improvements to differential voltage contrast and light and electron scanning beam analysis of solar cells
Authors: Therrien J. , Mil'Shtein S.
Published: June 2010

Differential voltage contrast (DVC) in conjunction with light and electron beam scanning (LEBEAMS) technique were used for measuring the electric potential, field, and charge distribution in solar cells. The DVC is based on enhancement or retardation of secondary electron emission, generated by an electron beam, due to local changes in the potential of a semiconductor device. The information provided by this technique is invaluable to the development of any device. Solar cells have been studied by the DVC technique, both under electrical bias (DVC) and under illumination (DVC in conjunction with LEBEAMS); however, the conditions of the previous did not replicate the normal illumination conditions of a solar cell. The goal of this research was to redesign and expand the previous LEBEAMS experiments to produce accurate profiles of quasi Fermi energies on solar cells.