bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation of Costimulatory Signal in Maternal–Fetal Immune Tolerance
Authors: Jin Li‐Ping , Fan Deng‐Xuan , Li Da‐Jin
Published: January 2011

Citation  Jin L‐P, Fan D‐X, Li D‐J. Regulation of costimulatory signal in maternal‐fetal immune tolerance. Am J Reprod Immunol 2011; 66: 76–83

A pregnancy is associated with modifications in the immune status of the mother, but the mechanisms are not well understood. Several observations have indicated that CD28/CTLA‐4 and B7‐1/B7‐2 are involved in the maternal–fetal immune regulation. This review aims to recapitulate our current knowledge concerning the role of CD28/CTLA‐4 and B7‐1/B7‐2 in maternal–fetal immune regulation. Several studies suggest that up‐regulation of B7‐2 and/or CD28 and/or down‐regulation of CTLA‐4 are correlated with the occurrence of pregnancy loss. Therefore, an accurate expression of costimulatory molecules at the maternal–fetal interface may ensure that the decidual cells do not elicit a ‘danger’ signal to the maternal immune system, perhaps instead contributing to the establishment of immune tolerance in vivo. It is showed that costimulation blockade with anti‐B7 mAbs results in altered allogeneic T‐cell response and overcomes increased maternal rejection to the fetus, which improves fetus growth in the abortion‐prone system. These findings suggest that the anti‐B7‐treated T cells not only function as potent suppresser cells but also exert immunoregulatory effect on the maternal T cells. This procedure might be potentially useful to immunotherapy for human recurrent spontaneous abortion.
Expression Profiles of Peripheral CD160+ Lymphocytes During the Course of Healthy Human Pregnancy
Authors: Barakonyi Aliz , Weisdorn Renata , Miko Eva , Varga Peter , Bodis Jozsef , Szekeres‐Bartho Julia , Szereday Laszlo
Published: January 2011

Citation
 Barakonyi A, Weisdorn R, Miko E, Varga P, Bodis J, Szekeres‐Bartho J, Szereday L. Expression profiles of peripheral CD160+ lymphocytes during the course of healthy human pregnancy. Am J Reprod Immunol 2011; 66: 137–142

Problem  CD160 receptor is expressed by natural killer (NK) and T‐cell subsets, and after activation, it could enhance cytotoxicity or pro‐inflammatory cytokine production on NK cells. Here, we investigated the phenotype of peripheral CD160+ cells during healthy pregnancy.

Method of study  We analyzed the expression of CD69 activation marker, gamma/delta TCR, and NKG2A or NKG2D NK cell receptors on CD160+ lymphocytes of non‐pregnant and healthy pregnant women at four different stages of pregnancy by flow cytometry.

Results  In our hands, CD160 receptor‐positive lymphocytes were present during pregnancy; however, they had different characteristics depending on gestational age. During implantation, CD160+ cells showed low activation rate, decreased NK receptor expression while 40% of Vδ2 + T cells expressed CD160 receptor. In turn, all the above parameters increased as pregnancy proceeds.

Conclusion  Our results indicate that CD160+ lymphocytes could be able to play a role in the maintenance of healthy pregnancy.
Clinical appearance, differential diagnoses and therapeutical options of chondrodermatitis nodularis chronica helicis Winkler
Authors: Wagner Gunnar , Liefeith Jan , Sachse Michael Max
Published: January 2011

The article on chondrodermatitis nodularis chronica helicis summarizes various clinical pictures and differential diagnoses of this entity. This lesion is usually characterized by a solid or cystic nodule but ulcerations or crusts may also occur. The most common differential diagnoses include benign or malignant tumours, which are often confused with chondrodermatitis nodularis chronica helicis. The characteristic pain associated with this condition may serve as an important diagnostic clue in order to rule out other differential diagnoses. The therapy of chondrodermatitis nodularis chronica helices encompasses several conservative as well as surgical treatment options.
MAGNETIC RESONANCE ANATOMY OF THE CARPUS OF THE HORSE DESCRIBED FROM IMAGES ACQUIRED FROM LOW‐FIELD AND HIGH‐FIELD MAGNETS
Authors: NAGY ANNAMARIA , DYSON SUE
Published: January 2011

Cadaver carpi of 30 mature horses with no history of carpal or proximal metacarpal pain were examined using low‐field (0.27 T) and high‐field (1.5 T) magnetic resonance imaging (MRI). Normal MRI anatomy in transverse, sagittal, and dorsal plane images was determined by comparison with anatomical specimens and standard texts. Subchondral bone and cortical bone thickness measurements were obtained from standardised sites. There was variable subchondral bone thickness in the radius and carpal bones; subchondral bone thickness was consistently larger at dorsal compared with palmar sites in the proximal row of carpal bones. The endosteal surface of the subchondral bone was smooth. The shape of the ulnar carpal bone was variable and one or more small osseous fragments were identified palmar to the bone in 5/30 limbs. There was no evidence to suggest that these were pathological fractures or avulsions of the lateral palmar intercarpal ligament. The amount of muscle tissue in the superficial and deep digital flexor tendons in the proximal aspect of the carpus varied, but none was present at the level of the middle carpal joint and distally. Several structures could be evaluated that cannot be imaged using radiography, ultrasonography, or arthroscopy, including the transverse intercarpal ligaments, the radiocarpal ligament, the short palmar carpal ligaments, and the carpometacarpal ligaments. Anatomical variations not previously described were identified, including the layers of the medial aspect of the carpal fascia. Knowledge of the variation in MRI appearance of the carpus of nonlame horses is helpful for interpretation of MR images of lame horses.
Modulation of F0F1‐ATP synthase activity by cyclophilin D regulates matrix adenine nucleotide levels
Authors: Chinopoulos Christos , Konràd Csaba , Kiss Gergely , Metelkin Eugeniy , Töröcsik Beata , Zhang Steven F. , Starkov Anatoly A.
Published: January 2011

Cyclophilin D was recently shown to bind to and decrease the activity of F0F1‐ATP synthase in submitochondrial particles and permeabilized mitochondria [Giorgio V et al. (2009) J Biol Chem, 284, 33982–33988]. Cyclophilin D binding decreased both ATP synthesis and hydrolysis rates. In the present study, we reaffirm these findings by demonstrating that, in intact mouse liver mitochondria energized by ATP, the absence of cyclophilin D or the presence of cyclosporin A led to a decrease in the extent of uncoupler‐induced depolarization. Accordingly, in substrate‐energized mitochondria, an increase in F0F1‐ATP synthase activity mediated by a relief of inhibition by cyclophilin D was evident in the form of slightly increased respiration rates during arsenolysis. However, the modulation of F0F1‐ATP synthase by cyclophilin D did not increase the adenine nucleotide translocase (ANT)‐mediated ATP efflux rate in energized mitochondria or the ATP influx rate in de‐energized mitochondria. The lack of an effect of cyclophilin D on the ANT‐mediated adenine nucleotide exchange rate was attributed to the ∼ 2.2‐fold lower flux control coefficient of the F0F1‐ATP synthase than that of ANT, as deduced from measurements of adenine nucleotide flux rates in intact mitochondria. These findings were further supported by a recent kinetic model of the mitochondrial phosphorylation system, suggesting that an ∼ 30% change in F0F1‐ATP synthase activity in fully energized or fully de‐energized mitochondria affects the ADP–ATP exchange rate mediated by the ANT in the range 1.38–1.7%. We conclude that, in mitochondria exhibiting intact inner membranes, the absence of cyclophilin D or the inhibition of its binding to F0F1‐ATP synthase by cyclosporin A will affect only matrix adenine nucleotides levels.

Structured digital abstract

 F0F1‐ATPase beta and CypD physically interact by cross‐linking study (View interaction)
Oxylipins in fungi
Authors: Brodhun Florian , Feussner Ivo
Published: January 2011

In nearly every living organism, metabolites derived from lipid peroxidation, the so‐called oxylipins, are involved in regulating developmental processes as well as environmental responses. Among these bioactive lipids, the mammalian and plant oxylipins are the best characterized, and much information about their physiological role and biosynthetic pathways has accumulated during recent years. Although the occurrence of oxylipins and enzymes involved in their biosynthesis has been studied for nearly three decades, knowledge about fungal oxylipins is still scarce as compared with the situation in plants and mammals. However, the research performed so far has shown that the structural diversity of oxylipins produced by fungi is high and, furthermore, that the enzymes involved in oxylipin metabolism are diverse and often exhibit unusual catalytic activities. The aim of this review is to present a synopsis of the oxylipins identified so far in fungi and the enzymes involved in their biosynthesis.
Three years with adult human brown adipose tissue
Authors: Nedergaard Jan , Bengtsson Tore , Cannon Barbara
Published: January 2011

The presence of active brown adipose tissue in adult humans has been recognized in general physiology only since 2007. The intervening three years established that the depots originally observed by 18F‐fluoro‐deoxy‐glucose positron emission tomography (FDG PET) scanning techniques really are brown adipose tissue depots because they are enriched for uncoupling protein 1 (UCP1). Reports of low apparent prevalence of brown adipose tissue based on retrospective studies of hospital records of FDG PET scans markedly underestimate true prevalence because such studies only reflect acute activity state; consequently, such retrospective studies cannot be conclusively analysed for factors influencing activity and amount of brown adipose tissue. Dedicated studies show that the true prevalence is 30–100%, depending on cohort. Warm temperature during the investigation—as well as adrenergic antagonists—inhibit tissue activity. There is probably no sexual dimorphism in the prevalence of brown adipose tissue. Outdoor temperature may affect the amount of brown adipose tissue, and the amount is negatively correlated with age and obesity. The presence of brown adipose tissue is associated with cold‐induced nonshivering thermogenesis, and the tissue may be a major organ for glucose disposal. The decline in brown adipose tissue amount with increasing age may account for or aggravate middle‐age obesity. Maintained activation of brown adipose tissue throughout life may thus protect against obesity and diabetes.
Comparative study of cisplatin and epirubicin in transcatheter arterial chemoembolization for hepatocellular carcinoma
Authors: Yamanaka Kenya , Hatano Etsuro , Narita Masato , Taura Kojiro , Yasuchika Kentaro , Nitta Takashi , Arizono Shigeki , Isoda Hiroyoshi , Shibata Toshiya , Ikai Iwao , Sato Tosiya , Uemoto Shinji
Published: January 2011

Aim:  Transcatheter arterial chemoembolization (TACE) is an established treatment for unresectable hepatocellular carcinoma (HCC). However, it is unclear which chemotherapeutic agent should be selected for TACE. The aim of this study was to compare the efficacy of cisplatin (CDDP) with that of epirubicin (EPI) in TACE for patients with unresectable or relapsed HCC.

Methods:  We performed a historical cohort study involving 131 patients treated with a first TACE, defined as either an initial treatment for previously untreated HCC or a first treatment for relapsed HCC after curative resections or ablations. Efficacy was estimated as the response rate (RR) and it was adjusted for the confounding factors that were defined in this study.

Results:  The RR were 62.5% (20/32) for the first TACE with CDDP and 51.5% (51/99) for that with EPI. In the adjusted analysis for a history of hepatectomy, percutaneous treatment combined with TACE and tumor factors, the odds ratio was 1.72 (95% confidence interval [CI] = 0.70–4.48). However, a test for interaction between the number of tumors and the chemotherapeutic agent was statistically significant (P = 0.016). In multiple HCC, the RR were 66.7% (10/17) for CDDP and 39.6% (30/46) for EPI. The odds ratio was 4.11 (95% CI = 1.14–17.2).

Conclusion:  CDDP may be more effective than EPI in TACE for multiple HCC. A randomized controlled study is needed to clarify the efficacy of CDDP in TACE in patients with multiple HCC.
Studies on virus kinetics using infectious fluorescence‐tagged hepatitis C virus cell culture
Authors: Yamamoto Machi , Sakamoto Naoya , Nakamura Tetsuya , Itsui Yasuhiro , Nakagawa Mina , Nishimura‐Sakurai Yuki , Kakinuma Sei , Azuma Seishin , Tsuchiya Kiichiro , Kato Takanobu , Wakita Takaji , Watanabe Mamoru
Published: January 2011

Aim:  Studies of the complete hepatitis C virus (HCV) life cycle have become possible with the development of a HCV‐JFH1 cell culture system.

Methods:  In this study, we constructed two fluorescence protein‐tagged recombinant JFH1 virus clones, JFH1‐EYFP and JFH1‐AsRed, as well as two corresponding clones with adaptive mutations, JFH1‐EYFP mutant and JFH1‐AsRed mutant, that and were as effective as JFH1 in producing infectious virus particles, and investigated their viral infection life cycles.

Results:  After infection of the fluorescence‐tagged mutant viruses, infected cells increased exponentially. In cells, EYFP or AsRed and NS5A were expressed as a fusion protein and co‐localized in core proteins. The rate of the cell–cell spread was dependent on the cell densities with a maximum of 102.5/day. Treatment of cells with interferon or a protease inhibitor suppressed expansion of virus‐positive cells.

Conclusion:  Taken together, these results indicate that fluorescence‐tagged HCV is a useful tool to study virus infection life cycles and to assist in the search for novel antiviral compounds.
No associations of polymorphisms in ADPRT with hepatitis B virus clearance and hepatocellular carcinoma occurrence in a Korean population
Authors: Lee Jin Sol , Kim Jeong‐Hyun , Park Byung‐Lae , Cheong Hyun Sub , Koh InSong , Kim Jason Yong‐ha , Park Tae Joon , Pasaje Charisse Flerida , Bae Joon Seol , Lee Hyo‐Suk , Kim Yoon Jun , Shin Hyoung Doo
Published: January 2011

Aim:  The human adenosine diphosphate ribosyl transferase (ADPRT) gene might significantly affect cancer by encoding poly(ADP‐ribose) polymerase 1 enzyme (PARP‐1) and promoting an important role in cellular responses to DNA damage, genomic stabilization and regulation of tumor suppressor genes. We explored whether polymorphisms of ADPRT affect clearance of hepatitis B virus (HBV) infection or risk of hepatocellular carcinoma (HCC) occurrence in a Korean HBV cohort.

Methods:  Genotyping was performed in a total of 1066 subjects composed of 434 spontaneously recovered (SR) subjects as normal controls and 632 chronic carriers (CC) of HBV who were further classified into 325 patients with liver cirrhosis (LC)/chronic hepatitis (CH) and 307 patients with HCC.

Results:  Logistic analyses of six common single nucleotide polymorphisms (SNP) and their haplotypes revealed that none of the polymorphisms were significantly associated with clearance of HBV infection and HCC occurrence, except for nominal evidence of association between haplotype 2 (ht2) with HBV clearance (P = 0.05). In the analysis of age of HCC occurrence which is an important factor in disease progression to HCC, results from Cox proportional hazards showed that none of the variants were significantly associated with onset age of HCC occurrence, although a nominal signal in ht4 (P = 0.03, but Pcorr > 0.05) was initially detected.

Conclusion:  Although ADPRT is an important gene for cellular responses and tumor regulations, our study provides evidence that ADPRT variations do not affect HBV clearance and HCC occurrence.
Neurological Causes of Diaphragmatic Paralysis in 11 Alpacas (Vicugna pacos)
Authors: Byers S. , Barrington G. , Nelson D. , Haldorson G. , Holt T. , Callan R.
Published: January 2011

Background:Diaphragmatic paralysis is a relatively uncommon medical condition in animals not reported in alpacas.

Objectives:Describe the signalment, physical examination, diagnostic testing, clinical, and histopathologic findings related to diaphragmatic paralysis in alpacas.

Animals:Eleven alpacas with spontaneous diaphragmatic paralysis.

Methods:A retrospective study examined medical records from a 10‐year period and identified 11 alpacas with confirmed diaphragmatic paralysis admitted to Washington State University and Colorado State University Veterinary Teaching Hospitals between September 2003 and October 2009.

Results:The 11 alpacas ranged in age from 2 to 12 months. Fluoroscopic imaging confirmed the presence of bilateral diaphragmatic paralysis in the 7 alpacas that were imaged. Arterial blood gas analyses showed hypercapnea, hypoxemia, and low oxygen saturation. Seven alpacas died or were euthanized between 2 and 60 days after onset of respiratory signs. Histopathologic examination of tissues found phrenic nerve degeneration in the 6 alpacas that were necropsied and additional long nerves examined demonstrated degeneration in 2 of these animals. Two animals had spinal cord lesions and 2 had diaphragm muscle abnormalities. No etiologic agent was identified in the alpacas.

Conclusions and Clinical Importance:The etiology for diaphragmatic paralysis in these alpacas is unknown. A variety of medical treatments did not appear to alter the outcome.
Bronchoalveolar Lavage Fluid Cytology and Cytokine Messenger Ribonucleic Acid Expression of Racehorses with Exercise Intolerance and Lower Airway Inflammation
Authors: Lavoie J.P. , Cesarini C. , Lavoie‐Lamoureux A. , Moran K. , Lutz S. , Picandet V. , Jean D. , Marcoux M.
Published: January 2011

Background: There is limited information relating bronchoalveolar lavage (BAL) cytology and cytokine messenger ribonucleic acid (mRNA) expression in racehorses with inflammatory airway disease (IAD).

Hypothesis and Objective: We hypothesize that cytokine expression in BAL cells would correlate with cytology. Thus, we evaluated the mRNA expression of selected cytokines in BAL cells in racehorses with exercise intolerance and lower airway inflammation.

Animals: Thirty‐one client‐owned Standardbred racehorses with exercise intolerance.

Methods: Prospective, observational study. Cells were obtained by BAL, and mRNA expression of interleukin (IL)‐1β, IL‐4, IL‐8, tumor necrosis factor (TNF)‐α, and interferon (IFN)‐γ was determined by reverse transcription quantitative polymerase chain reaction (RT‐qPCR).

Results: Nine horses had normal BAL cell differential cytology (Controls), while 22 horses had evidence of IAD based on BAL fluid cytology. Relative expressions of TNF‐α/glyceraldehyde 3‐phosphate dehydrogenase (GAPDH; 0.0092 ± 0.010 versus 0.0045 ± 0.005, P= .034), IL‐4/GAPDH (0.001 ± 0.002 versus 0.0003 ± 0.0003, P= .029), and IFN‐γ/GAPDH (0.0027 ± 0.003 versus 0.0009 ± 0.001, P= .028) were greater in horses with IAD compared with controls. Furthermore, IL‐4/GAPDH (0.001 ± 0.002 versus 0.0002 ± 0.0003, P < .0001) and IFN‐γ/GAPDH (0.003 ± 0.003 versus 0.001 ± 0.001, P= .002) mRNA expression was increased in horses with increased metachromatic cell counts compared with horses with normal metachromatic cell counts. Only the mRNA expression of IL‐1β/GAPDH (1.1 ± 0.7 versus 0.3 ± 0.3, P= .045) was increased with airway neutrophilia.

Conclusions and Clinical Importance: Differences in gene expression were associated with the presence of IAD and with specific cell types present in airway secretions of Standardbred racehorses with poor performance. These findings suggest that different pathophysiological pathways are implicated in IAD.
Comparison of Water Manometry to 2 Commercial Electronic Pressure Monitors for Central Venous Pressure Measurement in Horses
Authors: Norton J.L. , Nolen‐Walston R.D. , Underwood C. , Slack J. , Boston R. , Dallap B.L.
Published: January 2011

Background: Central venous pressure (CVP) customarily has been measured in veterinary patients with water manometry. However, many institutions are now using stallside electronic monitors in both anesthesia and intensive care units for many aspects of patient monitoring.

Hypothesis: Electronic stall side monitoring devices will agree with water manometry for measurement of CVP in horses.

Animals: Ten healthy adult horses from the university research herd.

Methods: Central venous catheters were placed routinely, and measurements were obtained in triplicate with each of the 3 methods every 12 hours for 3 days. Data were analyzed by a Lin concordance correlation coefficient and modified Bland‐Altman limits of agreement, with all devices compared pairwise.

Results: Compared with water manometry, agreement (bias) of the Passport was −1.94 cmH2O (95% limits of agreement, −8.54 to 4.66 cmH2O) and of the Medtronic was −1.83 cmH2O (95% limits of agreement, −8.60 to 4.94 cmH2O). When compared with the Passport, agreement of the data obtained with the Medtronic was 0.27 cmH2O (95% limits of agreement, −4.39 to 4.93 cmH2O).

Conclusions and Clinical Importance: These data show that both electronic monitors systematically provide measurements that are approximately 2 cmH2O lower than water manometry, but differences between the 2 electronic devices are small enough (< 0.5 cmH2O) to be considered clinically unimportant. This discrepancy should be taken into account when interpreting data obtained with these monitoring devices.
Effect of Parvoviral Enteritis on Plasma Citrulline Concentration in Dogs
Authors: Dossin O. , Rupassara S.I. , Weng H.‐Y. , Williams D.A. , Garlick P.J. , Schoeman J.P.
Published: January 2011

Background: Plasma citrulline concentration is a reliable marker of global enterocyte mass in humans and is markedly decreased in diffuse small intestinal diseases. However, the relationship between acute intestinal damage and plasma citrulline concentration in dogs has never been documented.

Hypothesis: That dogs with parvoviral enteritis have a lower plasma citrulline concentration than healthy dogs and that plasma citrulline concentration is a predictor of death in puppies with parvoviral enteritis.

Animals: Sixty‐one dogs with spontaneous parvoviral enteritis and 14 healthy age‐matched control dogs.

Methods: Observational cohort study. Plasma citrulline concentration was measured by liquid chromatography and tandem mass spectrometry in blood samples collected at admission and each day until death or discharge from the hospital. Parvovirus enteritis was confirmed by electron microscopy on a fecal sample.

Results: Median (interquartile range) plasma citrulline concentrations at admission were 2.8 μmol/L (range: 0.3, 49.0; P < .001 versus controls) in survivors (n = 49), 2.1 μmol/L (range: 0.5, 6.4, P < .001 versus controls) in nonsurvivors (n = 12) and 38.6 μmol/L (range: 11.4, 96.1) in controls (n = 14), respectively. There was no significant difference in plasma citrulline concentration between survivors and nonsurvivors within the parvovirus‐infected puppies, and plasma citrulline concentration was not significantly associated with outcome in parvoviral enteritis. There were no significant changes in plasma citrulline concentration over the 8‐day follow‐up period.

Conclusion and Clinical Importance: Parvovirus enteritis is associated with a severe decrease in plasma citrulline concentration that does not appear to have any significant prognostic value.
Density, porosity, and magnetic susceptibility of achondritic meteorites
Authors: MACKE Robert J. , BRITT Daniel T. , CONSOLMAGNO Guy J.
Published: January 2011

Abstract–

As part of a large‐scale survey of meteorite bulk and grain densities, porosities, and magnetic susceptibilities, we measured these properties for 174 stones from 106 achondritic meteorites. These include four lunar meteorites, 15 stones from 10 shergottites, nakhlites, and chassignites (SNCs), 96 stones from 56 howardites, eucrites, and diogenites (HEDs), 17 stones from nine aubrites, two angrites, and 16 stones from 10 ureilites, four stones of three acapulcoites, as well as four stones of three lodranites, and 15 stones from eight primitive achondrites. Those meteorites derived from basalts and crustal material of differentiated parent bodies have lower densities and magnetic susceptibilities, on an average, than the more primitive achondrites, which have a higher percentage metal. A notable exception is the one chassignite in the study (Chassigny), which has a high grain density of 3.73 ± 0.04 g cm−3. Ureilites have magnetic susceptibilities consistent with primitive achondrites, but lower grain densities. Porosities do not vary considerably between most of the groups, with most stones 5–14% porous, although on an average, ureilites and brachinites have lower porosities, with most stones less than 7% porous. For primitive achondrites, the higher metal content causes finds to exhibit weathering effects similar to what is observed in ordinary chondrites, with a reduction in grain density, magnetic susceptibility, and porosity as compared with unweathered falls. For lunites, SNCs, and HEDs, no such effect is observed. We also observe that grain density and magnetic susceptibility used in conjunction distinguish shergottites, nakhlites, and chassignites from each other. Shergottites and nakhlites have low grain densities (averaging 3.31 and 3.41 g cm−3, respectively) whereas Chassigny is 3.7 g cm−3. In magnetic susceptibility, shergottities and chassignites are similar (averaging 2.85 and 2.98 in log units of 10−9 m3 kg−1, respectively) with nakhlites averaging higher at 3.42.
Development of a General Dynamic Pressure Based Single-Phase Spray Cooling Heat Transfer Correlation
Authors: Abbasi Bahman , Kim Jungho
Published: January 2011

One of the main challenges of spray cooling technology is the prediction of local and average heat transfer coefficients on the heater surface. It is hypothesized that the local heat transfer coefficient can be predicted from the local normal pressure produced by the spray. In this study, hollow cone, full cone, and flat fan sprays, operated at three standoff distances, five spray pressures, and two nozzle orientations, were used to identify the relation between the impingement pressure and the heat transfer coefficient in the single-phase regime. PF-5060, PAO-2, and PSF-3 were used as test fluids, resulting in Prandtl number variation between 12 and 76. A microheater array operated at constant temperature was used to measure the local heat flux. A separate test rig was used to make impingement pressure measurements for the same geometry and spray pressure. The heat flux data were then compared with the corresponding impingement pressure data to develop a pressure-based correlation for spray cooling heat transfer. The maximum deviation between the experimental data and prediction was within ±25%.
Validation and Analysis of Numerical Results for a Varying Aspect Ratio Two-Pass Internal Cooling Channel
Authors: Shevchuk Igor V. , Jenkins Sean C. , Weigand Bernhard , von Wolfersdorf Jens , Neumann Sven Olaf , Schnieder Martin
Published: January 2011

Numerical results for an internal ribbed cooling channel including a 180 deg bend with a 2:1 inlet and a 1:1 aspect ratio outlet channel were validated against experimental results in terms of spatially resolved heat transfer distributions, pressure losses, and velocity distributions. The numerical domain consisted of one rib segment in the inlet channel and three ribs segments in the outlet channel to reduce the overall numerical effort and allow for an extensive parametric study. The results showed good agreement for both heat transfer magnitudes and spatial distributions, and the numerical results captured the predominate flow physics resulting from the 180 deg bend. The production of Dean vortices and acceleration of the flow in the bend produced strongly increased heat transfer on both the ribbed and unribbed walls in the outlet channel in addition to increases due to the ribs. Numerical simulations were performed for a wide range of divider wall-to-tip wall distances, which influenced the position of the highest heat transfer levels on the outlet walls and changed the shape of the heat transfer distribution on the tip wall. Analysis of section averages of heat transfer in the bend and outlet channel showed a strong influence of the tip wall distance, while no effect was seen upstream of the bend. A similarly large effect on pressure losses in the bend was observed with varying tip wall position. Trends in averaged heat transfer varied linearly with tip wall distance, while pressure losses followed a nonlinear trend, resulting in an optimum tip wall distance with respect to heat transfer efficiency.
Numerical Analysis of Specific Absorption Rate and Heat Transfer in the Human Body Exposed to Leakage Electromagnetic Field at 915 MHz and 2450 MHz
Authors: Wessapan Teerapot , Srisawatdhisukul Siramate , Rattanadecho Phadungsak
Published: January 2011

In recent years, society has increased utilization of electromagnetic radiation in various applications. This radiation interacts with the human body and may lead to detrimental effects on human health. However, the resulting thermophysiologic response of the human body is not well understood. In order to gain insight into the phenomena occurring within the human body with temperature distribution induced by electromagnetic field, a detailed knowledge of absorbed power distribution is necessary. In this study, the effects of operating frequency and leakage power density on distributions of specific absorption rate and temperature profile within the human body are systematically investigated. This study focuses attention on organs in the human trunk. The specific absorption rate and the temperature distribution in various tissues, obtained by numerical solution of electromagnetic wave propagation coupled with unsteady bioheat transfer problem, are presented.
Modeling of the Effect of Machining Parameters on Maximum Thickness of Cut in Ultrasonic Elliptical Vibration Cutting
Authors: Nath Chandra , Rahman Mustafizur , Neo Ken Soon
Published: January 2011

In recent years, the ultrasonic elliptical vibration cutting (UEVC) technique has been found to be an efficient method for the ultraprecision machining of hard and brittle materials. During the machining at a given nominal depth of cut (DOC), the UEVC technique, because of its inherent mechanism, effectively reduces the thickness of cut (TOC) of the workpiece material through overlapping vibration cycles. For the ductile machining of hard and brittle materials, this TOC plays a critical role. However, the relationships between the nominal DOC, the TOC, and the relevant machining parameters have not yet been studied. In this study, the role playing machining parameters for the TOC are firstly investigated and then theoretical relations are developed for predicting the maximum TOC (TOCm) with respect to the relevant machining parameters. It is found that four machining parameters, namely, workpiece cutting speed, tool vibration frequency, and tangential and thrust directional vibration amplitudes, influence the TOCm. If the speed ratio (ratio of the workpiece cutting speed to the maximum tool vibration speed in the tangential direction) is within a critical value 0.12837, then a reduced TOCm can be obtained. It is also realized that if the TOCm can be kept lower than the critical DOC (DOCcr), then ductile finishing of brittle materials can be achieved. The above phenomenon has been substantiated by experimental findings while machining a hard and brittle material, sintered tungsten carbide. The findings suggest that the same concept can be applied for the ductile cutting of other hard and brittle materials.
Sequential Laser Mechanical Microdrilling of Inconel 718 Alloy
Authors: Okasha M. M. , Mativenga P. T. , Li L.
Published: January 2011

Mechanical microdrilling of nickel-based aerospace alloys suffers from premature drill breakage due to the fragile nature of the microdrill. Additionally, burr size reduction in both macro- and microscales has become one of the key problems in the drilling process. This paper presents a new method to microdrill Inconel 718 alloy using laser followed by mechanical drilling (sequential drilling). The aim of this research was to understand and evaluate the capability of using sequential laser mechanical drilling method as an effective and efficient method in drilling difficult-to-cut metals. Two new approaches were developed, namely, a two-step process of laser pilot drilling followed by twist drilling and a three-step process of laser pilot hole drilling followed by mechanical pilot drilling and then twist drilling. The holes produced by the new approaches were compared with those by mechanical microdrilling (pilot drilling and then twisting drilling). The results show that mechanical drilling eliminates the laser drilling defects. Furthermore, while large nonuniform burrs with attached cap were found in pure mechanical drilling, 75% reduction in burr size was achieved with the complimentary sequential drilling technology. Additionally, when compared with purely mechanical microdrilling, the new drilling method resulted in 240–430% tool life increase. Thus, the new drilling method presents an opportunity for industry to extend tool life and decrease burr.
Robust Design for Dynamic System Under Model Uncertainty
Authors: Lu XinJiang , Li Han-Xiong
Published: January 2011

In real-world applications, a nominal model is often used to approximate the design of an industrial system. This approximation could make the traditional design method less effective due to the existence of model uncertainty. In this paper, a novel stability-based approach is proposed to design the system ensuring robust stability under model uncertainty. First, the design variables and their variation bounds are configured to make the system stable. Then, a robust design is developed to incorporate system eigenvalues that are less sensitive to model uncertainty. Finally, the tolerance of the design space will be maximized under given performance constraints. A simulation example is conducted to demonstrate the effectiveness of the proposed robust design method.
Defects in m-plane ZnO epitaxial films grown on (112) LaAlO3 substrate
Authors: Wang Wei-Lin , Peng Chun-Yen , Ho Yen-Teng , Chuang Shu-Chang , Chang Li
Published: January 2011

The crystallographic orientations of m-plane ZnO on (112) LaAlO3 (LAO) substrate are [1¯21¯0]ZnO∥[111¯]LAO and [0001]ZnO∥[1¯10]LAO. The defects in m-plane ZnO have been systematically investigated using cross section and plan-view transmission electron microscopy (TEM). High-resolution TEM observations in cross section show misfit dislocations and basal stacking faults (BSFs) at the ZnO/LAO interface. In the films, threading dislocations (TDs) with 1/3⟨112¯0⟩ Burgers vectors are distributed on the basal plane, and BSFs have 1/6⟨202¯3⟩ displacement vector. The densities of dislocations and BSFs are estimated to be 5.1×1010 cm−2 and 4.3×105 cm−1, respectively. In addition to TDs and BSFs, plan-view TEM examination also reveals that stacking mismatch boundaries mainly lie along the m-planes and they connect with planar defect segments along the r-planes.
Molecular beam epitaxy growth of InGaN-GaN superlattices for optoelectronic devices
Authors: Boney Chris , Starikov David , Hernandez Ivan , Pillai Rajeev , Bensaoula Abdelhak
Published: January 2011

In the absence of native substrates for InGaN films, the achievement of thick InGaN films of high structural quality remains a challenge. The investigation of InGaN-GaN superlattice (SL) structures is one potential way to increase optical absorption at energies below the GaN bandgap while reducing the formation of detrimental defects. In this article the authors evaluate the structural and optical properties of InGaN-GaN superlattices grown by plasma assisted molecular beam epitaxy with indium compositions of up to 38% and periods from 8 to 20 nm. Of primary concern was the degree of film relaxation as determined by x-ray diffraction (XRD) reciprocal space mapping as a function of indium content and thickness of the InGaN layers. Indium well fractions of up to 0.15 were found to exhibit little or no relaxation for the structures tested by x-ray diffraction. For indium well fractions near ∼0.2, relaxations of the superlattices were in the range of 35% depending on total layer thickness. The samples with indium fractions of 0.33 and 0.38 had relaxations near 30%. For all of the superlattice layers, the onset of absorption began at significantly lower energy if one compares the average indium fraction in the SL to a uniform InGaN film of the same fraction. p-n photodiode structures based on superlattice layers were fabricated and tested for I-V characteristics and spectral response. The high indium content superlattice devices exhibited a substantial spectral response extension down to ∼2.3 eV. However, the I-V behavior was leaky at both forward and reverse biases, which is in a good agreement with the XRD analysis showing that material relaxation and defect generation occur in the SL layers with higher indium content.
Novel VIM Metallo-β-Lactamase Variant, VIM-24, from a Klebsiella pneumoniae Isolate from Colombia
Authors: Montealegre Maria Camila , Correa Adriana , Briceño David F. , Rosas Natalia C. , De La Cadena Elsa , Ruiz Sory J. , Mojica Maria F. , Camargo Ruben Dario , Zuluaga Ivan , Marin Adriana , Quinn John P. , Villegas Maria Virginia ,   the Colombian Nosocomial Resistance Study Group
Published: January 2011

We report the emergence of a novel VIM variant (VIM-24) in a
Klebsiella pneumoniae
isolate in Colombia. The isolate displays MICs for carbapenems below the resistance breakpoints, posing a real challenge for its detection. The
bla
VIM-24
gene was located within a class 1 integron carried on a large plasmid. Further studies are needed to clarify its epidemiological and clinical impact.
Properties of a Nitrogen-Related Hole Trap Acceptor-Like State in p-Type GaAsN Grown by Chemical Beam Epitaxy
Authors: Bouzazi Boussairi , Suzuki Hidetoshi , Kojima Nobuaki , Ohshita Yoshio , Yamaguchi Masafumi
Published: January 2011

The properties of a nitrogen (N)-related hole trap HC2, located approximately 0.15 eV above the valence band maximum of GaAsN, and their relationship with the density of ionized acceptors (N
A) in p-type GaAsN grown by chemical beam epitaxy are investigated using deep level transient spectroscopy and on the basis of the temperature dependence of the junction capacitance. At room temperature, N
A is found to show a linear dependence on N concentration under N- and H-rich growth conditions. Furthermore, a N-dependent sigmoid increase in junction capacitance is observed in a specific temperature range from 70 to 100 K, which is the same as in the case where HC2 is recorded. Such behavior is explained by the thermal ionization of HC2, whose density affects in great part the magnitude order of N
A, essentially for a N concentration higher than 0.15%. Concerning its origin, HC2 is strongly considered to act as N–H related acceptor state.
Effects of Hydrogen Doping on the Electrical Properties of Zinc–Tin–Oxide Thin Films
Authors: Kim Hye-Ri , Kim Dong-Ho , Byon Eungsun , Lee Goo-Hyun , Lee Gun-Hwan , Song Pung-Keun
Published: January 2011

Transparent conducting oxide films composed of ZnO and SnO2 were prepared on glass substrates by co-sputtering method. After surveying the electrical properties of the films according to the cationic composition and process conditions, we investigated the influences of hydrogen doping on the films' characteristic properties. With a moderate addition of H2 in sputtering gas, carrier concentration of the films increased from 3.32×1019 to 5.22×1019 cm-3, and the resistivity decreased from 7.23×10-3 to 5.29×10-3 Ω·cm. The increase in carrier concentration with H2 can be attributed to the presence of hydrogen shallow donors as well as the formation of oxygen vacancies. However, the hydrogen addition contributed to the formation of SnO local states in Zn–Sn–O films, resulting in the decreases in carrier mobility and optical transmittance. Furthermore, changes in the electrical properties of the films upon annealing in vacuum or reducing atmosphere were investigated to elucidate the state of hydrogen atoms incorporated in Zn–Sn–O films.
Exciton Luminescence Dynamics in ZnO Crystal Observed under One- and Two-Photon Excitation
Authors: Yamamoto Sekika , Sakuma Hikari , Mishina Tomobumi
Published: January 2011

Free-exciton luminescence dynamics at the surface and deep inside of a ZnO single crystal are investigated by one- and two-photon excitation mothods. The free-exciton lifetime is carefully evaluated at each position by considering the excitonic diffusion effect and the trapping process inside the sample. The obtained temperature dependence of the lifetime indicates that the photon recycling effect dominates the exciton lifetime inside the sample while the K-selection rule determines the lifetime at the surface.
Theoretical Optimization of Base Doping Concentration for Radiation Resistance of InGaP Subcells of InGaP/GaAs/Ge Based on Minority-Carrier Lifetime
Authors: Elfiky Dalia , Yamaguchi Masafumi , Sasaki Takuo , Takamoto Tatsuya , Morioka Chiharu , Imaizumi Mitsuru , Ohshima Takeshi , Sato Shin-ichiro , Elnawawy Mohamed , Eldesoky Tarek , Ghitas Ahmed
Published: January 2011

One of the fundamental objectives for research and development of space solar cells is to improve their radiation resistance. InGaP solar cells with low base carrier concentrations under low-energy proton irradiations have shown high radiation resistances. In this study, an analytical model for low-energy proton radiation damage to InGaP subcells based on a fundamental approach for radiative and nonradiative recombinations has been proposed. The radiation resistance of InGaP subcells as a function of base carrier concentration has been analyzed by using the radiative recombination lifetime and damage coefficient K for the minority-carrier lifetime of InGaP. Numerical analysis shows that an InGaP solar cell with a lower base carrier concentration is more radiation-resistant. Satisfactory agreements between analytical and experimental results have been obtained, and these results show the validity of the analytical procedure. The damage coefficients for minority-carrier diffusion length and carrier removal rate with low-energy proton irradiations have been observed to be dependent on carrier concentration through this study. As physical mechanisms behind the difference observed between the radiation-resistant properties of various base doping concentrations, two mechanisms, namely, the effect of a depletion layer as a carrier collection layer and generation of the impurity-related complex defects due to low-energy protons stopping within the active region, have been proposed.
Effect of Base Doping Concentration on Radiation-Resistance for GaAs Sub-Cells in InGaP/GaAs/Ge
Authors: Elfiky Dalia , Yamaguchi Masafumi , Sasaki Takuo , Takamoto Tatsuya , Morioka Chiharu , Imaizumi Mitsuru , Ohshima Takeshi , Sato Shin-ichiro , Elnawawy Mohamed , Eldesuky Tarek , Ghitas Ahmed
Published: January 2011

GaAs solar cells with the lower base carrier concentration under low energy proton irradiations had shown experimentally the better radiation-resistance. Analytical model based on fundamental approach for radiative and non-radiative recombination has been proposed for radiation damage in GaAs sub-cells. The radiation resistance of GaAs sub-cells as a function of base carrier concentration has been analyzed by using radiative recombination lifetime and damage coefficient for minority carrier lifetime. Numerical analysis shows good agreement with experimental results. The effect of carrier concentration upon the change of damage constant and carrier removal rate have been studied.
Micro Defect Size in Si Single Crystal Grown by Czochralski Method
Authors: Moon Byeong-Sam , Sim Bok-Cheol , Park Jea-Gun
Published: January 2011

Single crystals for 300 mm wafer are grown by horizontal magnetic Czochralski method. 300 mm wafers are made from the vertical samples cut from crystal along ingot axial direction. Micro defects in various defect regions are investigated with various measurement methods. In order to investigate the size of the defects, the locations of defects are identified, the wafers with the defects are cut in cross-sectional direction, and the sizes of the defects are measured by transmission electron microscopy (TEM). The voids more than 20 nm size exist in vacancy-rich region. Any as-grown defect is not observed by any available measurement tools in the region having nuclei of oxidation-induced stacking fault (P-band), pure silicon in a vacancy-dominant crystal region (Pv), and pure silicon in an interstitial-silicon-dominant crystal region (Pi). High sensitive laser scattering tomography system with the detection limit of 20 nm size is used to investigate as-grown defects in P-band, Pi, and Pv regions. It is concluded that there are no as-grown defects more than 20 nm size in P-band, Pi, and Pv regions.
Structural Characterization of Sputtered Silicon Thin Films after Rapid Thermal Annealing for Active-Matrix Organic Light Emitting Diode
Authors: Mugiraneza Jean de Dieu , Miyahira Tomoyuki , Sakamoto Akinori , Chen Yi , Okada Tatsuya , Noguchi Takashi , Itoh Taketsugu
Published: January 2011

The microcrystalline phase obtained by adopting a two-step rapid thermal annealing (RTA) process for rf-sputtered silicon films deposited on thermally durable glass was characterized. The optical properties, surface morphology, and internal stress of the annealed Si films are investigated. As the thermally durable glass substrate allows heating of the deposited films at high temperatures, micro-polycrystalline silicon (micro-poly-Si) films of uniform grain size with a smooth surface and a low internal stress could be obtained after annealing at 750 °C. The thermal stress in the Si films was 100 times lower than that found in the films deposited on conventional glass. Uniform grains with an average grain size of 30 nm were observed by transmission electron microscopy (TEM) in the films annealed at 800 °C. These micro-poly-Si films have potential application for fabrication of uniform and reliable thin film transistors (TFTs) for large scale active-matrix organic light emitting diode (AMOLED) displays.
Modeling of Defects Generation in 300 mm Silicon Monocrystals during Czochralski Growth
Authors: Lee Sang Hun , Song Do Won , Oh Hyun Jung , Kim Do Hyun
Published: January 2011

Defect generation was usually predicted by using the V/G (where V is growth rate and G is axial temperature gradient at the interface of melt/solid) theory, but it was hard to get appropriate critical V/G value and the value could not show the distribution of grown-in defects. Otherwise, direct defect simulation is a very useful method of interpreting initial point defect behavior and micro void generation. In this research, the direct defect simulation was preformed with variable process parameters and optimized by comparing with experiment results. With optimized direct defect analysis, the critical V/G value was modified as 0.00155 cm2 min-1 K-1. The critical pulling rate range was defined as that has low residual point defect concentration in silicon crystal, thus a high-quality wafer can be obtained at the critical pulling rate. The initial point defect distribution and the critical pulling rate range were analyzed by using direct defect model. Additionally, the generation of micro void density was also calculated with variable pulling rates and compared with experiment results. In this research, the initial point defect incorporation and the tendency of micro void generation were well explained by using direct defect model.