bluuebunny/crossref_metadata_2025 huggingface dataset:
Human bocavirus infection in children with acute gastroenteritis in Japan and Thailand
Authors: Pham Ngan Thi Kim , Trinh Quang Duy , Chan‐It Wisoot , Khamrin Pattara , Nishimura Shuichi , Sugita Kumiko , Maneekarn Niwat , Okitsu Shoko , Mizuguchi Masashi , Ushijima Hiroshi
Published: December 2010

A total of 329 fecal specimens, which had been known to be negative for rotavirus, adenovirus, norovirus, sapovirus, and astrovirus, and which were collected from infants and children with acute gastroenteritis in Japan and Thailand during 2005–2008 were screened for human bocavirus (HBoV). HBoV was detected by PCR with a primer pair that amplified the NP1 region of its genome and was genotyped by sequencing of the VP1/VP2 region. Of the 329 samples tested, 6 (1.8%) were positive for HBoV. Of these, five samples were collected from Japan and one sample was from Thailand, and the detection rates of HBoV in each country were 2% and 1.2%, respectively. For the detected HBoV, the capsid VP1/VP2 gene of all HBoV strains was successfully sequenced. Four Japanese HBoV strains studied were clustered into group 1, while the remaining Japanese strain and a unique Thai strain belonged to group 2. No severe acute gastroenteritis associated with HBoV was noted. This study provides better understanding on the epidemiology of HBoV infections in children with acute gastroenteritis in Japan and Thailand. J. Med. Virol. 83:286–290, 2011. © 2010 Wiley‐Liss, Inc.
Clinical performance of the CLART human papillomavirus 2 assay compared with the hybrid capture 2 test
Authors: Pista Angela , Verdasca Nuno , Oliveira Ana
Published: December 2010

Persistent infection by high‐risk human papillomavirus (HR‐HPV) is a cause of cervical cancer. The use of HPV detection in cervical screening programs may improve the ability to identify women at risk of cervical cancer. Therefore, the development of appropriate methods for the detection of HR‐HPV is essential. The aim of this study was to evaluate the clinical performance of the CLART Human Papillomavirus 2 assay (CLART) in comparison with the Hybrid Capture 2 test (HC2), using a clinical cut‐off of cervical intraepithelial neoplasia grade 2 or worse. Discrepant results were analyzed further by the PapilloCheck HPV genotyping system. In the 425 studied women, HR‐HPV positivity rates were similar by both tests (CLART‐13 HR‐HPV: 63.1%; CLART‐17 HR‐HPV: 64.7%; HC2: 64.5%). Agreement between CLART‐13 HR‐HPV (κ = 0.969; concordance level 98.6%), CLART‐17 HR‐HPV (κ = 0.974; concordance level 98.8%), and HC2 were very good. When 13 HR‐HPV types were considered, the two tests showed a clinical sensitivity of 96% (95% CI: 92.6–97.9). The clinical specificity of CLART‐13 HR‐HPV was 73.6% (95% CI: 66.7–79.5) for cervical intraepithelial neoplasia grade 2 or worse, which was comparable to HC2 (71.4%; 95% CI: 64.3–77.5). When all 17 HR‐HPV types were considered, CLART showed a clinical sensitivity of 96.9% (95% CI: 93.8–98.5) and a clinical specificity of 71.9% (95% CI: 64.9–78.0). In conclusion, the CLART assay is efficient, sensitive, reproducible, and has a similar performance to HC2 for cervical intraepithelial neoplasia grade 2 or worse. Furthermore, this assay has the advantage of detecting and genotyping 35 HPV types by a single test, which can provide additional information on the predictive value of infection with HR‐HPV. J. Med. Virol. 83:272–276, 2011. © 2010 Wiley‐Liss, Inc.
Soluble CD30: A serum marker for Epstein–Barr virus‐associated lymphoproliferative diseases
Authors: Haque Tanzina , Chaggar Turren , Schafers Jenna , Atkinson Claire , McAulay Karen A. , Crawford Dorothy H.
Published: December 2010

The soluble form of CD30 (sCD30), a member of tumor necrosis factor receptor superfamily, has been used as a marker of disease activity in various lymphomas. Epstein–Barr virus (EBV) is a potent stimulator of CD30 expression. The study aims to evaluate whether sCD30 can be used as a diagnostic marker for EBV‐associated infectious mononucleosis (IM) and post‐transplant lymphoproliferative disease (PTLD). Plasma from EBV seropositive healthy controls (N = 90), acute IM patients (n = 90), non‐PTLD heart/lung transplant recipients (N = 30) and EBV‐positive PTLD patients (N = 23) was tested for sCD30 using a commercially available ELISA kit. EBV DNA was tested by real time quantitative polymerase chain reaction assay. Significantly higher sCD30 levels were observed in acute IM patients (median 242.9 ng/ml) compared to EBV seropositive controls (median 15.7 ng/ml; P < 0.0001). These levels were highest in IM patients within 14 days of onset of illness. PTLD patients had significantly higher sCD30 levels (median 94 ng/ml) than healthy controls (P < 0.0001) and transplant patients (median 27 ng/ml; P = 0.0007). EBV DNA was detected mostly in acute IM and PTLD patients. In both cases there was a significant correlation between sCD30 and EBV DNA levels in plasma (P < 0.0001). This study demonstrates that sCD30 and EBV DNA levels can be used as potential markers for diagnosis of IM and PTLD. J. Med. Virol. 83:311–316, 2011. © 2010 Wiley‐Liss, Inc.
Etiological role of human papillomavirus infection for inverted papilloma of the bladder
Authors: Shigehara Kazuyoshi , Sasagawa Toshiyuki , Doorbar John , Kawaguchi Shohei , Kobori Yoshitomo , Nakashima Takao , Shimamura Masayoshi , Maeda Yuji , Miyagi Tohru , Kitagawa Yasuhide , Kadono Yoshifumi , Konaka Hiroyuki , Mizokami Atsushi , Koh Eitetsu , Namiki Mikio
Published: December 2010

The status of human papillomavirus (HPV) infection in urothelial inverted papilloma was examined in the present study. Formalin‐fixed and paraffin‐embedded tissues from eight cases of inverted papilloma of the bladder were studied. The presence of HPV‐DNA was examined by modified GP5/6+PCR using archival tissue sections by microdissection. HPV genotype was determined with a Hybri‐Max HPV genotyping kit. Immunohistochemical analysis for p16‐INK4a, mcm7, HPV‐E4, and L1, and in situ hybridization for the HPV genome were performed. HPV was detected in seven of eight cases (87.5%) of inverted papilloma. Three cases were diagnosed as inverted papilloma with atypia, while the remaining five were typical cases. HPV‐18 was detected in two cases, including one inverted papilloma with atypia, and HPV‐16 was detected in four cases, including one inverted papilloma with atypia. Multiple HPV type infection was detected in one typical case and one atypical case. High‐risk HPV was present in all HPV‐positive cases. Cellular proteins, p16‐INK4a and mcm7, which are surrogate markers for HPV‐E7 expression, were detected in all HPV‐positive cases, and their levels were higher in inverted papilloma with atypia than in typical cases. In contrast, HPV‐E4 and L1, which are markers for HPV propagation, were observed in some parts of the typical inverted papilloma tissue. High‐risk HPV infection may be one of the causes of urothelial inverted papilloma, and inverted papilloma with atypia may have malignant potential. J. Med. Virol. 83:277–285, 2011. © 2010 Wiley‐Liss, Inc.
Epstein–barr virus in diffuse large B‐Cell lymphoma in immunocompetent patients in Japan is as low as in Western Countries
Authors: Wada Naoki , Ikeda Junichiro , Hori Yumiko , Fujita Shigeki , Ogawa Hiroyasu , Soma Toshihiro , Sugiyama Haruo , Fukuhara Shirou , Kanamaru Akihisa , Hino Masayuki , Kanakura Yuzuru , Morii Eiichi , Aozasa Katsuyuki
Published: December 2010

According to previous reports, the frequency of Epstein–Barr virus (EBV) positivity in diffuse large B‐cell lymphoma is higher in East Asia (approximately 9%) than in Western countries. The presence of the EBV genome was examined in diffuse large B‐cell lymphoma patients registered with the Osaka Lymphoma Study Group (OLSG) in Osaka, Japan, situated in East Asia. The EBV‐positive rate was examined with in situ hybridization (ISH) in 484 immunocompetent diffuse large B‐cell lymphoma patients registered with OLSG. The male‐to‐female ratio was 1.29, with ages ranging from 16 to 95 (median, 68) years. ISH with EBV‐encoded small RNAs (EBER) probes revealed positive signals in the nuclei of tumor cells: the frequency of positively stained cells among all tumor cells was almost none in 458 cases, 5–10% in 5, 10–20% in 5, 20–50% in 11, and >50% in 5. When the frequency was >20% or >50%, the EBV‐positive rate in the present series (3.3% or 1.0%) was rather similar to that reported in Western cases. Careful evaluation of patient backgrounds, including age distribution, type of lymphomas, exclusion of immunocompromised patients, and establishment of definite criteria for EBV positivity (>20%, >50%, or almost all tumor cells) are essential in comparing geographical differences. J. Med. Virol. 83:317–321, 2011. © 2010 Wiley‐Liss, Inc.
Variations in the functional domain of basal core promoter of hepatitis B virus among Eastern Indian patients with prevalence of genotypes A, C, and D among the same ethnic population
Authors: Biswas Avik , Banerjee Arup , Chandra Partha Kumar , Datta Sibnarayan , Panigrahi Rajesh , Dutta Deep , De Binay Krishna , Pal Manisha , Guha Subhashish Kamal , Chakrabarti Sekhar , Chakravarty Runu
Published: December 2010

Mutations in the basal core promoter (BCP) and precore (PC) regions are associated with persistent and intermittently high hepatitis B virus (HBV) replication in several patients. The variability in the functional domains of BCP and PC region of HBV and their association with disease progression and clinical outcome were assessed in Eastern India, an unique region where three HBV genotypes, A, D, and C are prevalent among the same ethnic group. PCR amplification and direct sequencing of BCP and PC region was done on sera obtained from 130 HBsAg positive subjects with different clinical presentations. Associations of the apparent risk factors with clinical advancement were evaluated by statistical methods including multiple logistic regression analyses (MLR). HBV genotype A was present in 33.08%, C in 25.38%, and D in 41.54% cases. Genotypes A and C were associated with higher rate of T1762/A1764 mutations than the most predominant genotype D. HBeAg negative state was associated with considerably higher rate of C1753 mutation. T1762/A1764 along with C1753 was common among cirrhosis and T1762/A1764 without C1753 was frequent among chronic liver disease cases. No significant association was found between A1896 point mutation and clinical status. Multivariate analysis revealed that T1762/A1764 double mutation, HBV/A, age ≥25 years, C1753 and A1899 were critical factors for clinical advancement while age ≥25 years and C1753 as significant predictor for cirrhosis in comparison with chronic liver disease. In conclusion, the analysis of the BCP variability may help in monitoring the progression towards advanced liver disease in Eastern Indian patients. J. Med. Virol. 83:253–260, 2011. © 2010 Wiley‐Liss, Inc.
Using detection of survivin‐expressing circulating tumor cells in peripheral blood to predict tumor recurrence following curative resection of gastric cancer
Authors: Cao Weiguo , Yang Weiping , Li Hao , Lou Guying , Jiang Jinsong , Geng Mei , Xi Wenqi , Ren Ruobing , Qu Qing , Jin Xiaolong , Zhu Yanbo , Jin Yening
Published: December 2010

Background and Objectives

The present study was designed to investigate the clinicopathological role of survivin‐expressing circulating tumor cells (CTCs) and to determine whether the presence of survivin‐expressing CTCs is an independent predictor of tumor recurrence following curative resection of gastric cancer.

Methods

This study included 98 patients who underwent potentially curative resection. Reverse transcription polymerase chain reaction enzyme linked immunosorbent assay (RT‐PCR ELISA) was used to measure survivin mRNA in peripheral blood.

Results

Of the 98 patients studied, 45 (45.9%) were positive for survivin mRNA. Survivin mRNA expression correlated with Lauren classification (P < 0.001), pathological tumor (pT) stage (P < 0.001), pathological tumor node metastasis (pTNM) stage (P = 0.009), and degree of differentiation (P = 0.001). The pTNM stage and the status of survivin mRNA were independent prognostic factors of disease‐free survival (P = 0.007 and <0.001, respectively).

Conclusions

The detection of CTCs expressing survivin mRNA could be a good clinical biomarker used to predict the prognosis of patients with curatively resected gastric cancer. J. Surg. Oncol. 2011; 103:110–115. © 2010 Wiley‐Liss, Inc.
Esophageal cancer—the five year survivors
Authors: Kim Tad , Grobmyer Stephen R , Smith Reshelle , Ben‐David Kfir , Ang Darwin , Vogel Stephen B , Hochwald Steven N
Published: December 2010

Background

Esophageal cancer in the United States carries a poor prognosis with overall 5 year survival rate of approximately 10%. Due to this dismal outcome, data analyzing factors predictive of survival for greater than 5 years are not available.

Methods

Single institution retrospective review of esophageal resection for curative intent from 1984 to 2004. We identified 50 actual 5 year survivors (long term survivors, LTS) out of 266 patients (19%) with invasive esophageal cancer and, using multivariate logistic regression, compared characteristics between the LTS, and short‐term (<5 year) survivors (STS).

Results

There was no significant difference in clinical T stage or N stage by EUS (P = 0.81) or in the utilization of neoadjuvant therapy in the LTS versus STS (58% vs. 62%, respectively, P = 0.36). The LTS group was significantly more likely to have pathologic complete response (69% vs. 41%, P < 0.001), lower pathologic T stage, i.e., pT0, pTis, or pT1 (83% vs. 45%, P < 0.001), pN0 stage (97% vs. 68%, P < 0.001), favorable tumor differentiation (well or well to moderate, 39% vs. 13%, P < 0.001), and absence of angiolymphatic (88% vs. 69%, P < 0.01) or perineural invasion (95% vs. 83%, P = 0.04). In comparing the factors predictive of outcome in LTS versus the STS with increasing relative risk, absence of perineural invasion (RR 0.41 (0.27, 0.61)), negative margins (RR 0.41 (0.29, 0.57)), absence of angiolymphatic invasion (RR 0.39 (0.30, 0.51)), pN0 stage (RR 1.37 (1.23, 1.52)), pT0 or pT1 (RR 1.85 (1.64, 2.07)), pathologic complete response (RR 2.02 (1.76, 2.31)), and favorable tumor grade (RR 3.00 (2.49, 3.61)) were associated with improved survival.

Conclusion

Tumor biological factors including favorable tumor grade may be the most important influence on 5 year actual survival in esophageal cancer. J. Surg. Oncol. 2011; 103:179–183. © 2010 Wiley‐Liss, Inc.
Temperature‐dependent kinetics for the ozonolysis of selected chlorinated alkenes in the gas phase
Authors: Leather Kimberley E. , McGillen Max R. , Ghalaieny Mohamed , Shallcross Dudley E. , Percival Carl J.
Published: December 2010

The ozonolysis of olefinic species is an important tropospheric process impacting on climate and human health. However, few studies have investigated these reactions as a function of temperature and even less information is available upon the effects of alkene heteroatomic substitution on the Arrhenius parameters. The electron‐withdrawing capacity of substituents about the olefinic bond strongly influences the rate of alkene ozonolysis. To understand better the effect of these substitutions, the temperature‐dependence of a series of ozone–chloroalkene reactions is investigated. Experiments were conducted in the EXTreme RAnge (EXTRA) chamber, over the range of 292–409 K and 760 Torr. The experimentally determined rate coefficients were fitted using an Arrhenius‐type analysis to yield the following activation energies: 30.80 ± 0.79, 23.18 ± 0.59, 65.2 ± 2.8, 116.9 ± 5.6, 29.5 ± 1.8, and 18.67 ± 0.96 kJ mol−1and preexponentialA‐factors 1.22+0.39−0.29×10−15, 9.3+6.7−5.4×10−16, 1.6+2.5−1.0×10−10, 6+22−3.9×10−4, 1.7+1.6−0.8×10−14, and 4.2+1.9−1.3×10−15cm3molecule−1s−1forcis‐1,2‐dichloroethene,trans‐1,2‐dichloroethene, trichloroethene, tetrachloroethene, 2‐chloropropene, and 3‐chloro‐1‐butene, respectively. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 43: 120–129, 2011
Formation of H‐atoms in the pyrolysis of cyclohexane and 1‐hexene: A shock tube and modeling study
Authors: Peukert Sebastian , Naumann Clemens , Braun‐Unkhoff Marina , Riedel Uwe
Published: December 2010

Cyclohexane (cC6H12) plays an important role in the combustion of practical liquid fuels, as a major component of naphthenic compounds. Therefore, the pyrolysis of cyclohexane was investigated by measuring the formation of H‐atoms. The thermal decomposition of 1‐hexene (1‐C6H12) was also studied, because of the assumption that 1‐hexene is the sole initial product of cyclohexane decomposition. For cyclohexane, the measurements were performed over a temperature range of 1320–1550 K, at pressures ranging from 1.8 to 2.2 bar; 1‐hexene experiments were done at temperatures between 1250 and 1380 K and pressures between 1.5 and 2.5 bar. For each experiment, the time‐dependent formation of H‐atoms was measured behind reflected shock waves by using the method of atomic resonance absorption spectrometry. For the dissociation of 1‐hexene to n‐propyl (C3H7) and allyl (C3H5) radicals, the following Arrhenius expression was derived: kR2(T) = 2.3 × 1016 exp(−36,672 K/T) s−1. For cyclohexane, overall rate coefficients (kov) were deduced for the global reaction cC6H12 → products + H from the H‐atom time profiles; the following temperature dependency was obtained: kov(T) = 4.7 × 1016 exp(−44,481 K/T) s−1. For both sets of rate coefficient values, an uncertainty of ±30% is estimated. Especially concerning the isomerization cC6H12 → 1‐C6H12, our experimental results are in excellent agreement with the rate coefficient values given by Tsang (Tsang, W. Int J Chem Kinet 1978, 10, 1119–1138). A reaction model was assembled that is able to reproduce the H‐atom profiles measured for both sets of experiments. According to this model, H‐atoms are mostly stemming from the thermal decomposition of allyl radicals (C3H5), which arise from the decomposition of 1‐hexene. Furthermore, it will be shown that the recombination of allyl radicals with H‐atoms to propene (C3H6) also represents a very important subsequent reaction. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 43: 107–119, 2011
Bioactivity and emerging role of short and medium chain fatty acids
Authors: Huth Peter J. , Fulgoni Victor , Jandacek Ronald J. , Jones Peter J. , St‐Onge Marie‐Pierre , Senanayake Vijitha
Published: December 2010

Cardiovascular disease (CVD) and insulin resistance are directly linked to overweight and obesity. Thus, any dietary strategy capable of causing weight reduction will lower CVD and diabetes risk. Oils rich in medium‐chain saturated fatty acids (MCFA) are among several dietary components that may have potential in the treatment of obesity. MCFA are less energy dense and highly ketogenic compared to long‐chain saturated and unsaturated fatty acids (LCFA). MCFA also differ from LCFA in their digestive and metabolic pathways, since they are easily oxidized and utilized as energy, with little tendency to deposit as body fat. The dietary intake of short (SCFA) and medium‐chain saturated fatty acids from natural food sources is approximately 2.4 g/day and accounts for about 9% of the total saturated fatty acid (SFA) intake. Although early clinical studies with high levels of MCFA resulted in increased levels of plasma triacylglycerols (TAG) and low‐density lipoprotein cholesterol (LDL‐C), and reduced levels of high‐density lipoprotein cholesterol (HDL‐C) compared to diets enriched in unsaturated LCFA, these adverse effects have not been observed in more recent studies with smaller more realistic amounts of MCFA. The lower caloric value of SCFA and MCFA and their unique metabolic features form the basis for their clinical use in enteral and parenteral nutrition and for novel reduced calorie lipids for use in conventional food products.
Using Spherical Harmonic Surface Property Representations for Ligand‐Based Virtual Screening
Authors: Pérez‐Nueno Violeta I. , Venkatraman Vishwesh , Mavridis Lazaros , Clark Tim , Ritchie David W.
Published: December 2010

Ligand‐based virtual screening (VS) techniques have become well established in the drug discovery process. However, despite their relative success, there still exists the problem of how to define the initial query compounds and which of their conformations should be used. Here, we propose a novel shape plus surface property approach using multiple local spherical harmonic (SH) functions. We also investigate the use of shape‐based and shape plus property‐based consensus SH queries calculated in several different ways. The utility of these approaches is compared using the 40 pharmaceutically relevant targets of the DUD database. Our results show that using a combination of SH‐based properties often gives better VS performance than using simple shape‐based queries. Shape‐based consensus queries also perform well, but we find that explicit 3D shape‐property conformations should be retained for highly flexible ligands.
An international urogynecological association (IUGA)/international continence society (ICS) joint terminology and classification of the complications related directly to the insertion of prostheses (meshes, implants, tapes) and grafts in female pelvic floor surgery
Authors: Haylen Bernard T. , Freeman Robert M. , Swift Steven E. , Cosson Michel , Davila G. Willy , Deprest Jan , Dwyer Peter L. , Fatton Brigitte , Kocjancic Ervin , Lee Joseph , Maher Chris , Petri Eckhard , Rizk Diaa E. , Sand Peter K. , Schaer Gabriel N. , Webb Ralph
Published: December 2010

Introduction and hypothesis

A terminology and standardized classification has yet to be developed for those complications arising directly from the insertion of synthetic (prostheses) and biological (grafts) materials in female pelvic floor surgery.

Methods

This report on the above terminology and classification combines the input of members of the Standardization and Terminology Committees of two International Organizations, the International Urogynecological Association (IUGA) and the International Continence Society (ICS) and a Joint IUGA/ICS Working Group on Complications Terminology, assisted at intervals by many expert external referees. An extensive process of 11 rounds of internal and external review took place with exhaustive examination of each aspect of the terminology and classification. Decision‐making was by collective opinion (consensus).

Results

A terminology and classification of complications related directly to the insertion of prostheses and grafts in female pelvic floor surgery has been developed, with the classification based on category (C), time (T) and site (S) classes and divisions, that should encompass all conceivable scenarios for describing insertion complications and healing abnormalities. The CTS code for each complication, involving three (or four) letters and three numerals, is likely to be very suitable for any surgical audit or registry, particularly one that is procedure‐specific. Users of the classification have been assisted by case examples, colour charts and online aids (www.icsoffice.org/complication).

Conclusion

A consensus‐based terminology and classification report for prosthesis and grafts complications in female pelvic floor surgery has been produced, aimed at being a significant aid to clinical practice and research. Neurourol. Urodynam. 30:2–12, 2011. © 2010 Wiley‐Liss
Resource allocation by means of project networks: Dominance results
Authors: Leus Roel
Published: December 2010

This article investigates the relationship between resource allocation and early‐start policies (ES‐policies), which are a type of scheduling policies introduced for stochastic scheduling and which can be represented by a directed acyclic graph. We present a formal treatment of resource flows as a representation of resource‐allocation decisions, extending the existing literature. Our results lead to suggestions for efficiency enhancements to enumeration algorithms for ES‐policies. © 2010 Wiley Periodicals, Inc. NETWORKS, Vol. 58(1), 50–58 2011
GRASP with path relinking heuristics for the antibandwidth problem
Authors: Duarte A. , Martí R. , Resende M.G.C. , Silva R.M.A.
Published: December 2010

This article proposes a linear integer programming formulation and several heuristics based on GRASP and path relinking for the antibandwidth problem. In the antibandwidth problem, one is given an undirected graph with n nodes and must label the nodes in a way that each node receives a unique label from the set {1, 2,…,n}, such that, among all adjacent node pairs, the minimum difference between the node labels is maximized. Computational results show that only small instances of this problem can be solved exactly (to optimality) with a commercial integer programming solver and that the heuristics find high‐quality solutions in much less time than the commercial solver. © 2010 Wiley Periodicals, Inc. NETWORKS, Vol. 58(3), 171–189 2011
On LP relaxations for the pattern minimization problem
Authors: Aloisio Alessandro , Arbib Claudio , Marinelli Fabrizio
Published: December 2010

We discuss two formulations of the pattern minimization problem: (1) introduced by Vanderbeck, and (2) obtained adding setup variables to the cutting stock formulation by Gilmore‐Gomory. Let z(u) be the bound given by the linear relaxation of (i) under a given vector u of parameters. We show that z(u) ≥ z(u) and provide a class of instances for which the inequality holds strict. We observe that the linear relaxation of both formulations can be solved by the same column generation procedure and discuss the critical role of parameter u. The article is completed by a numerical test comparing the lower bounds obtained through (1) and (2) for different values of u. © 2011 Wiley Periodicals, Inc. NETWORKS, 2011
Influence of diamond nanoparticles on the thermal properties of benzocyclobutene (BCB)
Authors: Gracias A. , Tokranova N. , Thelen B. C. M. , Castracane J.
Published: December 2010

This paper describes the influence of diamond nanoparticles on the modification of the thermal properties of benzocyclobutene (BCB) which is used for three‐dimensional (3D) wafer‐to‐wafer integration. Hybrid nanocomposites containing mixtures of 0.5–10 weight% (wt.%) diamond nanoparticles [average particle size (APS): 10 nm] in BCB were analyzed using thermal gravimetric analysis (TGA) and flash diffusivity techniques. Measurements show that the addition of nanoparticles significantly increases the decomposition temperature. Diffusivity measurements and subsequent calculations of thermal conductivity suggest that the inclusion of nanoparticles only slightly improves the conductivity.
Highly indistinguishable photons from a quantum dot in a microcavity
Authors: Weiler Stefanie , Ulhaq Ata , Ulrich Sven M. , Reitzenstein Stephan , Löffler Andreas , Forchel Alfred , Michler Peter
Published: December 2010

We investigated the indistinguishability of photons emitted by single self‐assembled (In,Ga)As/GaAs quantum dots (QDs) coupled to the fundamental mode (FM) of a pillar microcavity. By systematic pre‐characterization, optimum conditions with respect to fast radiative decay (Purcell enhancement), long coherence time, and close to background‐free single‐photon emission have been derived. For different spectral detunings between QD and FM emission, Hong‐Ou‐Mandel‐type (HOM) two‐photon interference has been measured as a function of temporal photon wavepacket overlap. Detailed analysis of our data (under consideration of setup limitations) anticipates the generation of highly indistinguishable photons with up to VHOM = 0.82 visibility.
Evidence of two disorder scales in Ga(AsBi)
Authors: Imhof Sebastian , Wagner Christian , Chernikov Alexej , Koch Martin , Kolata Kolja , Köster Niko S. , Chatterjee Sangam , Koch Stephan W. , Lu Xiangfeng , Johnson Shane R. , Beaton Daniel A. , Tiedje Thomas , Rubel Oleg , Thränhardt Angela
Published: December 2010

Temperature‐dependent photoluminescence in a Ga(AsBi) structure is modelled in an excitonic hopping model and compared to experiment. It is shown that theory and experiment cannot be brought into agreement when using a single energy scale. Thus, a second energy scale is introduced, resulting in a good agreement between theory and experiment. The two scales are identified with spatially large alloy disorder and additional cluster states subdividing this first scale.
A semiconductor model for the single quantum dot laser
Authors: Gies C. , Florian M. , Gartner P. , Jahnke F.
Published: December 2010

The emission properties of a single quantum‐dot laser are studied on the basis of a semiconductor model. Coulomb interaction and excitation‐induced effects like dephasing and screening lead to an interplay of excitonic and biexcitonic emission contributions at the cavity frequency. In the input/output curve and photon statistics, this leads to novel features that cannot be explained in terms of atomic models for a single‐emitter laser. Rather, they are a result of the particular properties of the QD emitter.
First‐principles modeling of the interactions of iron impurities with graphene and graphite
Authors: Boukhvalov Danil W.
Published: December 2010

Results of first‐principles modeling of interactions of graphene and graphite with iron impurities predict the colossal difference between these two carbon allotropes. Insertion of the iron atoms between the planes of graphite is much more energetically favorable than adsorption of the iron ad atom at the graphite or graphene surface. High mobility of iron ad atom over graphite surface and within bulk graphite is reported. Calculated values of formation energies for the substitutional iron impurities suggest that iron is more destructive for graphite than for graphene. This effect caused formation of a uniform carbon environment of the iron atom inside the multilayer system. In contrast to graphene, segregation of the substitutional iron impurities in graphite under ambient conditions is not energetically favorable. Enhancement of interlayer bonding in contaminated graphite and purity of graphene from iron impurities are also reported.

magnified image

Interstitial iron ad atom (left) and pair of substitutional iron ad atoms (right) inside bulk graphite.
Study of microwave surface resistance of type‐II superconductors carrying transport current
Authors: Yıldız Şükrü , İnanır Fedai , Kölemen Uğur
Published: December 2010

We investigate the microwave surface resistance of an infinitely long type‐II superconductor in the critical state carrying transport DC current, in the absence and in the presence of external magnetic fields. Calculations include both different cooling processes and various current and field arrangements. Theoretical results in field‐cooled sample show that the microwave surface resistance exhibits an initial slow variation followed by a faster one above a threshold current value. This occurs when the current induced magnetic field generates fluxons of opposite directions on the two sample edges.
Hydrogen‐related defects in boron doped p‐type silicon
Authors: Malmbekk H. , Vines L. , Monakhov E. V. , Svensson B. G.
Published: December 2010

The interaction between hydrogen and irradiation‐induced defects in boron‐doped silicon has been investigated in search of a passivation procedure for intrinsic defects, applicable for the solar cell industry. Deep level transient spectroscopy (DLTS) and minority carrier transient spectroscopy (MCTS) have been applied for defect characterization of proton implanted p‐type Fz and Cz‐Si, with a boron concentration of 2x1016 cm–3 and 4x1014 cm–3, respectively. MCTS reveals a dominant electron trap located 0.22 eV below the conduction band edge (Ec) which is commonly ascribed to a boron‐interstitial oxygen‐interstitial complex (BiOi). DLTS reveals several hole traps at 0.09, 0.18, 0.25, 0.35, 0.46 and 0.52 eV above the valence band edge (Ev). The levels at 0.09, 0.18 and 0.35 eV are identified as the carbon‐interstitial carbon‐substitutional pair (CiCs), the divacancy center (V2) and the carbon‐interstitial oxygen‐interstitial pair (K‐center), while the levels located at 0.25 and 0.52 eV have previously been suggested to result from defect complexes containing hydrogen. After annealing at 100‐200 °C for 30 min the measurements show that the H(0.25) level increases in amplitude, while V2 and the K‐center decrease in amplitude. Heat treatment at 125 °C leads to almost complete disappearance of V2 and the K‐center in the Fz samples. The obtained results suggest that the loss of V2 and the K‐center is due to interaction with H. A possible identification of the Ev+0.2 5eV level will be discussed. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dry texturing of mc‐Si wafers
Authors: Agarwal Garima , De Iuliis Simona , Serenelli Luca , Salza Enrico , Tucci Mario
Published: December 2010

Texturing of mc‐Si is a prevailing research topic to improve solar cell efficiency in production. Surface texturing for enhanced absorption in Si has been historically obtained by creating randomly distributed pyramids using anisotropic etchants; but this preferential etching works only on single crystalline silicon because of its crystallographic orientations. A low‐cost, large area, random, mask‐less texturing scheme is expected to significantly impact terrestrial PV technology and reduce the amount of wet‐chemical waste. We propose an approach based on randomly etched mc‐Si by RIE system using NF3 instead of SF6 or CF4 to reduce the detrimental formation of carbonaceous or sulfurous contamination at the silicon surface, which results in a surface recombination. To obtain a fast process we have investigated the effect of the chemical etching due to the NF3 radicals and the ion bombardment induced by Ar. We have found that Arions promote a helpful surface pre‐conditioning, while fluorine radicals, produced by NF3 dissociation, are needed to increase the Si etching rate. Different combinations of flux ratios, gas pressures and RF power have been explored. Efforts have been devoted in obtaining a homogeneous texture on large area wafers, which is inescapable for industrialization. After 10 minutes process effective reflectance values have been measured within the range of 12‐14%, and with a‐Si/SiNx the value reduced to 7%. Post‐processing minority carrier lifetime values in the range of 10 microseconds have been measured without applying any further chemical cleaning. Additionally, microscopic analysis has been performed to evaluate the surface microstructure morphology (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulations of silicon nanocrystals embedded in oxide for nanoelectronic applications
Authors: Armeanu Dumitru , Leroy Yann , Cordan Anne‐Sophie
Published: December 2010

The purpose of this paper is to report the results of a study on single electron charging of a nanocrystal floating gate in a metal‐oxide‐semiconductor transistor. Our model is based on the geometrical and physical parameters of hypothetically spherical nanocrystals embedded in oxide (nanocrystal radius, distance between nanocrystals, oxide thickness, bulk band structure). This model can be numerically solved through a two‐dimensional finite element approach.

The channel and gate electrodes are described through energy subbands, and the silicon nanocrystal through discrete energy levels. Two types of tunnel transport are considered here: indirect tunneling from the channel to the nanocrystal and then from the nanocrystal to the gate, and direct tunneling from the channel to the gate. We show that the latter type can be neglected for the current range of nanocrystal densities used for memory applications (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Scanning tunneling microscopy investigations of the epitaxial growth of ZrB2 on Si(111)
Authors: Fleurence Antoine , Yamada‐Takamura Yukiko
Published: December 2010

By means of Scanning Tunneling Microscopy (STM), elongated structures observed in ZrB2 thin films epitaxially grown on Si(111) have been determined to be ZrB2 crystallites misoriented from the dominant orientation of ZrB2(0001)//Si(111). The epitaxial relationships ZrB2(11$ \bar 2 $0)//Si(111) and ZrB2(1$ \bar 1 $00)//Si(111) were identified together with the in‐plane ZrB2[0001]//Si[1$ \bar 1 $0] orientation. The surface of these crystallites exhibits a well‐defined ZrB2 (1$ \bar 1 $00) – (2 × 6) surface re‐ construction, which is observed for the first time. The presence of large ZrB2(1$ \bar 1 $00) facets indicates that this surface contributes significantly to the growth of misoriented ZrB2 crystallites as well as to their elongated shape. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Research on efficiency limiting defects and defect engineering in silicon solar cells ‐ results of the German research cluster SolarFocus
Authors: Riepe Stephan , Reis Isolde E. , Kwapil Wolfram , Falkenberg Marie Aylin , Schön Jonas , Behnken Herfried , Bauer Jan , Kreßner‐Kiel Denise , Seifert Winfried , Koch Wolfgang
Published: December 2010

Defects in multicrystalline silicon for photovoltaic applications and their impact on solar cell parameters have been investigated in the material research network project SolarFocus. A series of multicrystalline silicon ingots of ultrapure feedstock material were cast with intentional addition of typical transition metal impurities (Fe, Cu, Cr) and Ge as doping elements. The results of lifetime measurements, NAA and FTIR analysis, solar cell processing and microscopic investigations are presented in this study. For ingots intentionally contaminated with transition metals, the combined analysis reveals that despite the overall high impurity content, good solar cell efficiencies can be reached. A strong influence of the in‐diffusion of metal impurities from the crucible as well as the back‐diffusion from the top region of the ingot ca still be observed. All metals show a strong precipitation behaviour throughout the whole ingot. The solar cell efficiency is both limited by multiple recombination active defects and shunts, induced by a high metal contamination via indirect mechanisms. Solar cells with efficiencies up to 15.2% for material contaminated with 20 ppma Fe in the melt, 15.7% for 20 ppma Cu and 15.1% for 20 ppma Cr were processed. A positive effect of Cu added to the feedstock could not be found. Ge‐rich ingots showed strong effects of increasing silicon carbide and silicon nitride formation with increasing Ge content larger than 0.5 wt.% thus reducing solar cell efficiency. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Chemical characterization of SiC and Si3N4 precipitates in multicrystalline silicon by NIR microscopy and ToF‐SIMS
Authors: Richter Susanne , Kaufmann Kai , Hagendorf Christian
Published: December 2010

During the crystallization process of multicrystalline silicon precipitates may be formed, which can cause electrical and mechanical problems in the later manufacturing process of solar cells. Typical precipitates in multicrystalline silicon (mc‐Si) ingots are SiC and Si3N4, the exact chemical composition is not known until now, especially regarding dopants. After localization with near infrared (NIR) microscopy, we used Time‐of‐Flight Secondary Ion Mass Spectrometry (ToF‐SIMS) for chemical investigations. Reproducible fingerprints of the elemental composition for several SiC and Si3N4 precipitates were determined and it is shown that characteristic polyatomic fragments can be assigned to each type of precipitate. Doping elements in the different precipitates explain the origin of the electrical conductivity. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
FEM for modelling 193 nm excimer laser treatment of SiO2/Si/Si(1‐x)Gex heterostructures on SOI substrates
Authors: Conde J. C. , Martín E. , Chiussi S. , Gontad F. , González P.
Published: December 2010

Research on epitaxial crystaline silicon (c‐Si) and silicon‐germanium (Si1‐xGex) alloys growth and annealing for microelectronic purposes, such as Micro‐ or Nano‐Electro‐Mechanical Systems (MEMS or NEMS) and Silicon–On‐Nothing (SON) devices is continuously in progress. Laser assisted annealing techniques using commercial ArF Excimer Laser sources are based on ultra‐rapid heating and cooling cycles induced by the 193 nm pulses of 20 ns, which are absorbed in the near surface region of the heterostructures. During and after the absorption of these laser pulses, complex physical processes appear that strongly depend on sample structure and applied laser pulse energy densities. The control of the experimental parameters is therefore a key task for obtaining high quality alloys. The Finite ElementsMethod (FEM) is a powerful tool for the optimization of such treatments, because it provides the spatial and temporal temperature fields that are produced by the laser pulses. In this work, we have used a FEM commercial software, to predict the temperatures gradients induced by ArF excimer laser over a wide energy densities range, 0.1<Φ <0.4 J/cm2, on different SiO2/Si/Si(1‐x)Ge(x) thin films deposited on SOI substrate. These numerical results allow us to predict the threshold energies needed to reach the melting point (MP) of the Si and SiGe alloy without oxidation of the thin films system. Therefore, it is possible to optimize the conditions to achieve high quality epitaxy films. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The source of room temperature ferromagnetism in granular GaMnAs layers with zinc blende clusters
Authors: Lawniczak‐Jablonska K. , Libera J. , Wolska A. , Klepka M. T. , Dluzewski P. , Sadowski J. , Wasik D. , Twardowski A. , Kwiatkowski A. , Sato K.
Published: December 2010

Granular GaAs:(Mn,Ga)As films were prepared by annealing the Ga0.985Mn0.015As/GaAs layers at 500 °C or 600 °C. It is commonly accepted that this processing should result in the formation of cubic or hexagonal MnAs clusters, respectively. We demonstrate that such a priori assumption is not justified. If in the as grown sample there are not many defects with the interstitial Mn atoms, only small cubic clusters can be formed even after annealing at 600 °C. Moreover, in a sample containing solely cubic GaMnAs clusters, the Mn ions are ferromagnetically coupled at room temperature. This fact was explained by the existence of GaMnAs solid solution in the clusters, with content of Mn close to 20% (higher than ever found in the layers) as was confirmed by experiment and theory. Extended X‐ray absorption spectroscopy studies excluded the possibility of formation of the hypothetic zinc blende MnAs clusters. Not more than one Mn atom was detected in the second shell around central Mn atom. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
New developments at the recent update of the IIW recommendations for fatigue of welded joints and components
Authors: Hobbacher Adolf F.
Published: December 2010

The International Institute of Welding (IIW) has published its first comprehensive recommendation on fatigue design of welded structures in 1996. The document appeared in English, French, German and Japanese. The idea was to describe the fatigue properties of welded joints and components independently from application groups with their specific preferences and interests. So, a comprehensive code was established, which covered all current methods of verification, such as component testing, nominal stress, structural stress, notch stress method as well as fracture mechanics assessment procedures. Detailed guidance for assessment of weld imperfections was also given. The outlined safety philosophy covers the different strategies and provides a detailed choice for the designer. The document had a considerable impact on code making bodies and thus it became an important source for the Eurocode. After more than one decade, a new update of the IIW recommendations has been published. The main areas of update are firstly a new consideration of high cycle fatigue in the grid of the Woehler S‐N curves, a standardized meshing for the structural hot‐spot stress concept, which allows now an economic and coarser meshing in finite element analysis, further on the extension of the effective notch stress concept to welded aluminium structures, followed by a numerical assessment of post weld treatments for improving the fatigue properties, and finally a new approach to cumulative damage in connection with multi‐axial stress. The update is a result of a worldwide collaboration of leading research institutions and it is expected that the new update will have the same impact on design and codes as the preceding document.
A longitudinal examination of positioning strategies in a liberalized developing African economy: The case of Ghana
Authors: Blankson Charles , Strutton David
Published: December 2010

This article examines the nature of positioning strategies pursued by companies (domestic and foreign) conducting business in a liberalized developing African economy, Ghana, over a ten‐year period. Specifically, this research deals with the aggregate behaviors of firms operating in Ghana's post‐SAP (structural adjustment program)‐induced environment. The findings reveal that the dominant positioning strategies are the brand name (branding tactics) and value for money (affordability). However, more recently, attractiveness, which implies elegance about the offering, has also emerged as a prominent positioning strategy. Evidence that supports the robustness of companies' adoption of positioning strategies within sub‐Saharan African economies is also developed. The results also suggest that firms doing business in sub‐Saharan African marketplaces characterized by an open and liberalized business climate have no choice but to become competitive in their positioning and with the aim of targeting the mass market and the lower‐middle‐class target audiences. © 2011 Wiley Periodicals, Inc.
Laparoscopic Organ‐Sparing Resection of Von Hippel‐Lindau Disease‐Associated Pancreatic Neuroendocrine Tumors
Authors: von Dücker Laura , Walz Martin K. , Voss Christian , Arnold Georg , Eng Charis , Neumann Hartmut P. H.
Published: December 2010

Background

Pancreatic neuroendocrine tumors (PNETs) are a characteristic feature of the tumor syndromes multiple endocrine neoplasia type 1 (MEN‐1) and von Hippel‐Lindau disease (VHL). With VHL, about 10% of the patients exhibit PNETs by age 40 years. Metastatic potential is high if the tumors have grown to >3 cm in diameter. Optimal surgical treatment is still a challenge.

Methods

We report three cases, all women, ages 22, 30, and 39 years, respectively, who had known VHL, confirmed by classic organ manifestations and germline mutations of the VHL gene. All were diagnosed, in an asymptomatic stage, with solid tumors of the pancreatic tail or tail/corpus area measuring 2.9–5.6 cm diameter. All accepted the offer of laparoscopic organ‐sparing removal of the tumors.

Results

In all three cases, the tumor was entirely removed. In two cases, resection of the spleen was also necessary as dissection of the tumor from the major splenic vessels was impossible. Operating time was 215–365 min, and blood loss was 200–700 ml. Histolopathology revealed benign PNETs in two cases, but the third patient had regional lymph node metastases. There were no complications, and the hospital stay was 4–7 days.

Conclusions

Organ‐sparing laparoscopic surgery is an important option for treating VHL‐associated PNETs of the pancreatic tail.