bluuebunny/crossref_metadata_2025 huggingface dataset:
Information processing without brains – the power of intercellular regulators in plants
Authors: Busch Wolfgang , Benfey Philip N.
Published: March 2010

Plants exhibit different developmental strategies than animals; these are characterized by a tight linkage between environmental conditions and development. As plants have neither specialized sensory organs nor a nervous system, intercellular regulators are essential for their development. Recently, major advances have been made in understanding how intercellular regulation is achieved in plants on a molecular level. Plants use a variety of molecules for intercellular regulation: hormones are used as systemic signals that are interpreted at the individual-cell level; receptor peptide-ligand systems regulate local homeostasis; moving transcriptional regulators act in a switch-like manner over small and large distances. Together, these mechanisms coherently coordinate developmental decisions with resource allocation and growth.
Direct activation of Shroom3 transcription by Pitx proteins drives epithelial morphogenesis in the developing gut
Authors: Chung Mei-I , Nascone-Yoder Nanette M. , Grover Stephanie A. , Drysdale Thomas A. , Wallingford John B.
Published: March 2010

Individual cell shape changes are essential for epithelial morphogenesis. A transcriptional network for epithelial cell shape change is emerging in Drosophila, but this area remains largely unexplored in vertebrates. The distinction is important as so far, key downstream effectors of cell shape change in Drosophila appear not to be conserved. Rather, Shroom3 has emerged as a central effector of epithelial morphogenesis in vertebrates, driving both actin- and microtubule-based cell shape changes. To date, the morphogenetic role of Shroom3 has been explored only in the neural epithelium, so the broad expression of this gene raises two important questions: what are the requirements for Shroom3 in non-neural tissues and what factors control Shroom3 transcription? Here, we show in Xenopus that Shroom3 is essential for cell shape changes and morphogenesis in the developing vertebrate gut and that Shroom3 transcription in the gut requires the Pitx1 transcription factor. Moreover, we show that Pitx proteins directly activate Shroom3 transcription, and we identify Pitx-responsive regulatory elements in the genomic DNA upstream of Shroom3. Finally, we show that ectopic expression of Pitx proteins is sufficient to induce Shroom3-dependent cytoskeletal reorganization and epithelial cell shape change. These data demonstrate new breadth to the requirements for Shroom3 in morphogenesis, and they also provide a cell-biological basis for the role of Pitx transcription factors in morphogenesis. More generally, these results provide a foundation for deciphering the transcriptional network that underlies epithelial cell shape change in developing vertebrates.
Cochlear outer hair cells undergo an apical circumference remodeling constrained by the hair bundle shape
Authors: Etournay Raphaël , Lepelletier Léa , de Monvel Jacques Boutet , Michel Vincent , Cayet Nadège , Leibovici Michel , Weil Dominique , Foucher Isabelle , Hardelin Jean-Pierre , Petit Christine
Published: March 2010

Epithelial cells acquire diverse shapes relating to their different functions. This is particularly relevant for the cochlear outer hair cells (OHCs), whose apical and basolateral shapes accommodate the functioning of these cells as mechano-electrical and electromechanical transducers, respectively. We uncovered a circumferential shape transition of the apical junctional complex (AJC) of OHCs, which occurs during the early postnatal period in the mouse, prior to hearing onset. Geometric analysis of the OHC apical circumference using immunostaining of the AJC protein ZO1 and Fourier-interpolated contour detection characterizes this transition as a switch from a rounded-hexagon to a non-convex circumference delineating two lateral lobes at the neural side of the cell, with a negative curvature in between. This shape tightly correlates with the ‘V’-configuration of the OHC hair bundle, the apical mechanosensitive organelle that converts sound-evoked vibrations into variations in cell membrane potential. The OHC apical circumference remodeling failed or was incomplete in all the mouse mutants affected in hair bundle morphogenesis that we tested. During the normal shape transition, myosin VIIa and myosin II (A and B isoforms) displayed polarized redistributions into and out of the developing lobes, respectively, while Shroom2 and F-actin transiently accumulated in the lobes. Defects in these redistributions were observed in the mutants, paralleling their apical circumference abnormalities. Our results point to a pivotal role for actomyosin cytoskeleton tensions in the reshaping of the OHC apical circumference. We propose that this remodeling contributes to optimize the mechanical coupling between the basal and apical poles of mature OHCs.
Actomyosin contractility and Discs large contribute to junctional conversion in guiding cell alignment within the Drosophila embryonic epithelium
Authors: Simone Robert P. , DiNardo Stephen
Published: March 2010

Proper control of epithelial morphogenesis is vital to development and is often disrupted in disease. After germ band extension, the cells of the Drosophila ventral embryonic epidermis are packed in a two-dimensional polygonal array. Although epithelial cell rearrangements are being studied productively in several tissues, the ventral epidermis is of particular interest as the final cell arrangement is, uniquely, far from equilibrium. We show that over the course of several hours, a subset of cells within each parasegment adopts a rectilinear configuration and aligns into parallel columns. Live imaging shows that this is accomplished by the shrinkage of select cell interfaces, as three-cell junctions are converted to four-cell junctions. Additionally, we show that non-muscle Myosin II and the polarity proteins Discs large (Dlg) and Bazooka are enriched along cell interfaces in a complex but reproducible pattern that suggests their involvement in junctional conversion and cell alignment. Indeed, depletion of Myosin II or dlg disrupts these processes. These results show that tight spatial regulation of actomyosin contractility is required to produce this high-energy arrangement of cells.
CCM1 regulates vascular-lumen organization by inducing endothelial polarity
Authors: Lampugnani Maria Grazia , Orsenigo Fabrizio , Rudini Noemi , Maddaluno Luigi , Boulday Gwénola , Chapon Francoise , Dejana Elisabetta
Published: March 2010

Little is known about the molecular mechanisms that regulate the organization of vascular lumen. In this paper we show that lumen formation correlates with endothelial polarization. Adherens junctions (AJs) and VE-cadherin (VEC, encoded by CDH5) are required for endothelial apicobasal polarity in vitro and during embryonic development. Silencing of CDH5 gene expression leads to abrogation of endothelial polarity accompanied by strong alterations in lumenal structure. VEC co-distributes with members of the Par polarity complex (Par3 and PKCζ) and is needed for activation of PKCζ. CCM1 is encoded by the CCM1 gene, which is mutated in 60% of patients affected by cerebral cavernous malformation (CCM). The protein interacts with VEC and directs AJ organization and AJ association with the polarity complex, both in cell-culture models and in human CCM1 lesions. Both VEC and CCM1 control Rap1 concentration at cell-cell junctions. We propose that VEC, CCM1 and Rap1 form a signaling complex. In the absence of any of these proteins, AJs are dismantled, cell polarity is lost and vascular lumenal structure is severely altered.
Role of intramembrane charged residues in the quality control of unassembled T-cell receptor α-chains at the endoplasmic reticulum
Authors: Soetandyo Nia , Wang Qiuyan , Ye Yihong , Li Lianyun
Published: March 2010

Endoplasmic reticulum (ER)-associated degradation (ERAD) of unassembled T-cell receptor α-chain (TCRα) is reliant on the presence of two basic residues in the transmembrane (TM) segment of TCRα. The precise role of these residues in ER quality control is unclear. Here, we show that a TCRα mutant lacking these intramembrane charged residues has a tendency to form homooligomers through an interchain disulfide bond that involves a specific pair of cysteine residues. Covalent oligomerization of TCRα appears to stabilize it at the ER membrane. The presence of a single lysine residue at specific positions within the TCRα TM domain abolishes its oligomerization and causes its rapid degradation. Conversely, when TCRα oligomerization is induced by a bivalent compound, the degradation of TCRα is inhibited. Together, these results suggest that the intramembrane charged residues in TCRα do not function as a signal for substrate recognition in ERAD. Instead, their primary role is to reduce TCRα oligomerization, maintaining it in a retrotranslocation-competent state. Our results also suggest that the ERAD machinery is inefficient when coping with oligomerized substrates, indicating a requirement for chaperone-mediated protein disassembly in the ER lumen prior to retrotranslocation.
MRG15 binds directly to PALB2 and stimulates homology-directed repair of chromosomal breaks
Authors: Hayakawa Tomohiro , Zhang Fan , Hayakawa Noriyo , Ohtani Yasuko , Shinmyozu Kaori , Nakayama Jun-ichi , Andreassen Paul R.
Published: March 2010

PALB2 physically and functionally connects the proteins encoded by the BRCA1 and BRCA2 breast and ovarian cancer genes into a DNA-damage-response network. However, it remains unclear how these proteins associate with chromatin that contains damaged DNA. We show here that PALB2 binds directly to a conserved chromodomain protein, MRG15, which is a component of histone acetyltransferase-deacetylase complexes. This interaction was identified by analysis of purified MRG15- and PALB2-containing protein complexes. Furthermore, MRG15 interacts with the entire BRCA complex, which contains BRCA1, PALB2, BRCA2 and RAD51. Interestingly, MRG15-deficient cells, similarly to cells deficient in PALB2 or BRCA2, showed reduced efficiency for homology-directed DNA repair and hypersensitivity to DNA interstrand crosslinking agents. Additionally, knockdown of MRG15 diminished the recruitment of PALB2, BRCA2 and RAD51 to sites of DNA damage and reduced chromatin loading of PALB2 and BRCA2. These results suggest that MRG15 mediates DNA-damage-response functions of the BRCA complex in chromatin.
A Versatile Approach to 2-Substituted 3-Trifluoromethyl-1,3-diols Based on the Reaction of Trifluoroacetaldehyde Ethyl Hemiacetal with Enamines Derived from Aldehydes
Authors: Funabiki Kazumasa , Furuno Yudai , Sato Fumiaki , Gonda Hiroshi , Kubota Yasuhiro , Matsui Masaki
Published: March 2010

Treatment of trifluoroacetaldehyde ethyl hemiacetal with various enamines, derived from various aldehydes, at room temperature, followed by hydrolysis with 10% HCl aqueous solution and reduction with sodium borohydride in ethanol, gave 2-substituted 3-trifluoromethyl-1,3-diols in good yields with fair to good diastereoselectivities.
Cost-effectiveness of a programme to detect and provide better care for female victims of intimate partner violence
Authors: Norman Richard , Spencer Anne , Eldridge Sandra , Feder Gene
Published: March 2010

Objective:

Primary care clinicians often fail to detect women who are victims of intimate partner violence (IPV). Our aim wasto investigate the cost-effectiveness of a programme in primary care to detect and support such women.

Methods:

We developed a Markov model to estimate the cost-effectiveness of education and support for primary care clinicians to increase their identification of survivors of IPV and to refer them to a specialist advocacy agency or a psychologist with specialist skills. The programme was implemented in three general practices in the United Kingdom (with an additional practice acting as a control) and provided cost data and rates of identification and referral. Other cost data and the effectiveness of IPV advocacy came from published sources.

Results:

The model gave an incremental cost-effectiveness ratio (ICER) of approximately £2,450 per quality adjusted life year (QALY). Although the ratio increased in some of the sensitivity analyses, most were under a conventional willingness to pay threshold (£30,000/QALY).

Conclusions:

While there is considerable uncertainty in the underlying parameters, a training programme for primary care teams to increase identification and referral of women experiencing IPV is likely to be cost-effective.
Ordering Behavior in Retail Stores and Implications for Automated Replenishment
Authors: van Donselaar Karel H. , Gaur Vishal , van Woensel Tom , Broekmeulen Rob A. C. M. , Fransoo Jan C.
Published: March 2010

Retail store managers may not follow order advices generated by an automated inventory replenishment system if their incentives differ from the cost-minimization objective of the system or if they perceive the system to be suboptimal. We study the ordering behavior of retail store managers in a supermarket chain to characterize such deviations in ordering behavior, investigate their potential drivers, and thereby devise a method to improve automated replenishment systems. Using orders, shipments, and point-of-sale data for 19,417 item–store combinations over five stores, we show that (i) store managers consistently modify automated order advices by advancing orders from peak to nonpeak days, and (ii) this behavior is explained significantly by product characteristics such as case pack size relative to average demand per item, net shelf space, product variety, demand uncertainty, and seasonality error. Our regression results suggest that store managers improve upon the automated replenishment system by incorporating two ignored factors: in-store handling costs and sales improvement potential through better in-stock. Based on these results, we construct a method to modify automated order advices by learning from the behavior of store managers. Motivated by the management coefficients theory, our method is efficient to implement and outperforms store managers by achieving a more balanced handling workload with similar average days of inventory.
Causal ordering of academic self‐concept and achievement: Effects of type of achievement measure
Authors: Pinxten Maarten , de Fraine Bieke , van Damme Jan , D'Haenens Ellen
Published: March 2010

Background. The relation between academic self‐concept and achievement has been examined in a large number of studies. The majority of these studies have found evidence for a reciprocal effects model. However, there is an ongoing debate on how students' achievement should be measured and whether the type of achievement indicator (grades, tests, teacher ratings) affects the causal pattern found in these studies.

Aims. The study aims at clarifying how the types of achievement measures and the way they are modelled can affect the results of causal ordering studies. In that sense, the study will yield recommendations for researchers in this domain and also provide some direction for practitioners seeking ways to enhance their students' achievement and/or academic self‐concept.

Sample. Repeated measures of academic self‐concept and achievement (standardized tests and teacher ratings) were examined in a sample of 1,753 students in Grades 7, 8, 10, and 12.

Method. Structural equation modelling was used. Several models (with different types and numbers of achievement measures) were compared.

Results. Only small differences were found between models using one or two indicators of achievement. All models generally supported the reciprocal effects model. However, the final model, wherein tests and teacher ratings were used as separate latent variables, showed different developmental patterns in the causal relation between academic self‐concept and achievement.

Conclusions. Researchers should interpret the results of causal ordering studies discerningly because the type of measure chosen as an indicator of achievement might affect the causal pattern between academic self‐concept and achievement.
Supporting early oral language skills for English language learners in inner city preschool provision
Authors: Dockrell Julie E. , Stuart Morag , King Diane
Published: March 2010

Background. A significant number of children now enter formal education in England with reduced levels of proficiency in oral language. Children who come from disadvantaged backgrounds and who are English language learners (ELL) are at risk of limited oral language skills in English which impacts on later educational achievement.

Aims. This paper reports the development of a theoretically motivated oral language intervention, Talking Time, designed to meet the needs of preschool children with poor language skills in typical preschool provision.

Sample. One hundred and forty‐two 4‐year‐old children attending three inner city preschools in a disadvantaged area of London, England.

Method. This is a quasi‐experimental intervention study comparing children exposed to Talking Time with children exposed to a contrast intervention and children receiving the statutory early years curriculum. Measures were taken of both targeted and non‐targeted language and cognitive skills.

Results. Data were analysed for the ELL. The intervention had a significant effect on vocabulary, oral comprehension, and sentence repetition but not narrative skills. As predicted, there were no effects on the skills which were not targeted.

Conclusions. Regular evidence‐based oral language interactions can make significant improvements in children's oral language. There is a need to examine the efficacy of more intensive interventions to raise language skills to allow learners to access the curriculum.
Theory of mind skills 1 year after traumatic brain injury in 6‐ to 8‐year‐old children
Authors: Chertkoff Walz Nicolay , Owen Yeates Keith , Gerry Taylor H. , Stancin Terry , Wade Shari L.
Published: March 2010

This study examined the longer‐term effects of traumatic brain injury (TBI) on theory of mind (ToM) skills of children who were between the ages of 5 and 7 years at the time of injury. Fifty‐two children with orthopaedic injury, 30 children with moderate TBI, and 12 children with severe TBI were evaluated approximately 1 year post‐injury (mean age=6.98 years, SD=0.59, range=6.02–8.26). Children with severe TBI did not engage in representation of first‐ and second‐order mental states at a developmental level comparable to their peers, suggesting stagnation or lack of development, as well as regression of putatively existing ToM skills. Age, task‐specific cognitive demands, and verbal abilities were strong predictors of ToM performance. However, even after taking those factors into account, children with severe TBI had poorer ToM performance than children with orthopaedic injuries.
A New Alternative for Estimation of Geotechnical Engineering Parameters in Reclaimed Clays by Using Shear Wave Velocity
Authors: Chang Ilhan , Cho Gye-Chun
Published: March 2010

The consolidation behavior of reclaimed clay can be categorized as large strain deformation. Findings from previous studies indicate that the effective stress and the void ratio are important geotechnical engineering parameters for the characterization of large strain consolidation behavior. However, existing in situ consolidation characterization methods of reclaimed clay cannot adequately estimate changes of the effective stress and void ratio during a consolidation process. This paper suggests an alternative method for estimating the geotechnical engineering parameters of reclaimed clays using a shear wave. An in situ self-weight consolidation process of reclaimed clay is simulated in laboratory while shear wave velocity is continuously measured. Experimental results show that there are single trends in relationships among the shear wave velocity, effective stress, void ratio, and geotechnical engineering parameters for a normally consolidated clay (e.g., reclaimed clay). As a practical application, the in situ parameters and the expected settlement are predicted by incorporating the obtained relationships with the in situ shear wave velocity. The predicted values are in good accordance with the values measured in field. Therefore, the proposed method can be used effectively for geotechnical engineering parameter estimations of reclaimed clay during/after self-weight consolidation with the aid of in situ seismic exploration techniques.
Improving the Thermal Resistance of Brick Masonry Systems
Authors: Sanders John P. , Brosnan Denis A.
Published: March 2010

Finite element modeling was used to relate the coring or cell configuration of brick to the heat flow through brick masonry wall systems. Core or cell configurations that minimize thermal bridging through the brick thickness substantially reduced the heat flow through the masonry. The effect of bed depth on heat flow was also investigated. Larger units with optimized coring designs resulted in substantial reductions in heat flow. Heat flow through the mortar joint was also compared to heat flow through the brick. Wall designs that minimize the mortar joint thickness also reduce the heat flow. From these simulations, it is clear that a masonry system can be optimized to reduce heat flow. The effect of core or cell filling with various materials was also studied. Insulating materials reduce heat flow primarily by displacing mortar in the cores or cells.
Coal and Coke Volatile Matter Determination and Reconciliation of Differences in Yields Determined by Two ASTM Methods
Authors: Riley John T. , Yanes Enrique G. , Marsh Mason , Lawrenz Dennis , Eichenbaum Liliane
Published: March 2010

For over 2 decades, fuel scientists have tried to reconcile the differences between the coal and coke volatile matter yields obtained using either a pre-heated (950°C) minimum volume vertical furnace (ASTM Method D3175) or a macro thermogravimetric analyzer (TGA) system heated to a final temperature of 950°C (macro TGA systems are those using 1 g or larger samples). This paper will describe experiments designed to help explain the differences in volatile matter yields. Parameters studied include sample heating rates, final temperatures, and pre-drying samples. Factors contributing to the differences between the two methods, such as observed differences between plastic and non-plastic coals and fixation of sulfur as sulfate in the pyrolysis residues, will be explained. Results from two interlaboratory studies, each involving over 10 laboratories, and other research projects were used to derive predictive equations to reconcile results from the two methods for determining volatile matter yields in coals.
Wright and Fisher on Inbreeding and Random Drift
Authors: Crow James F
Published: March 2010

Sewall Wright and R. A. Fisher often differed, including on the meaning of inbreeding and random gene frequency drift. Fisher regarded them as quite distinct processes, whereas Wright thought that because his inbreeding coefficient measured both they should be regarded as the same. Since the effective population numbers for inbreeding and random drift are different, this would argue for the Fisher view.
Accurate Prediction of Genetic Values for Complex Traits by Whole-Genome Resequencing
Authors: Meuwissen Theo , Goddard Mike
Published: March 2010

Whole-genome resequencing technology has improved rapidly during recent years and is expected to improve further such that the sequencing of an entire human genome sequence for $1000 is within reach. Our main aim here is to use whole-genome sequence data for the prediction of genetic values of individuals for complex traits and to explore the accuracy of such predictions. This is relevant for the fields of plant and animal breeding and, in human genetics, for the prediction of an individual's risk for complex diseases. Here, population history and genomic architectures were simulated under the Wright–Fisher population and infinite-sites mutation model, and prediction of genetic value was by the genomic selection approach, where a Bayesian nonlinear model was used to predict the effects of individual SNPs. The Bayesian model assumed a priori that only few SNPs are causative, i.e., have an effect different from zero. When using whole-genome sequence data, accuracies of prediction of genetic value were >40% increased relative to the use of dense ∼30K SNP chips. At equal high density, the inclusion of the causative mutations yielded an extra increase of accuracy of 2.5–3.7%. Predictions of genetic value remained accurate even when the training and evaluation data were 10 generations apart. Best linear unbiased prediction (BLUP) of SNP effects does not take full advantage of the genome sequence data, and nonlinear predictions, such as the Bayesian method used here, are needed to achieve maximum accuracy. On the basis of theoretical work, the results could be extended to more realistic genome and population sizes.
Industry and Injury Related Hospital Contacts: A Follow‐up Study of Injuries among Working Men in Denmark
Authors: Pedersen Betina Holbæk , Hannerz Harald , Tüchsen Finn , Mikkelsen Kim Lyngby , Dyreborg Johnny
Published: March 2010

Industry and Injury Related Hospital Contacts: A Follow‐up Study of Injuries among Working Men in Denmark: Betina Holbæk Pedersen, et al. National Research Centre for the Working Environment, Denmark

Objectives

To estimate proportions of injuries that are attributable to the work environment (excess fractions) among economically active men and to identify industries associated with an elevated injury risk.

Methods

A follow‐up study was conducted among all economically active men in Denmark aged 20–59 yr 1 January 1999 (N=1,315,772) for first hospital contacts in the period 1999–2003 due to injury in five body regions. Age standardised hospital treatment ratios (SHR) were calculated by industry and excess fractions were estimated.

Results

The excess fractions by body region attributable to the work environment were: 22% (95% CI 18–26%) for lower extremities, 29% (95% CI 24–34%) for head and neck, 31% (95% CI 25–37%) for thorax, 36% (95% CI 30–43%) for upper extremities, and 39% (CI: 32–46%) for back injuries. We identified eight industries associated with significantly elevated risks for injuries to each of the five body regions. These were: “road contractors”, “bricklayer, joiner, and carpentry work”, “finishing (construction work)”, “transport of goods”, “fire service and salvage corps”, “stone‐works, pottery, and glass industry”, “cleaning, laundries, and dry cleaners”, and “slaughterhouse industry”.

Conclusions

There are substantial industrial inequalities in injury rates among male workers in Denmark. The size of the inequalities differs between body regions.
Multicenter Study of Repeat Epinephrine Treatments for Food-Related Anaphylaxis
Authors: Rudders Susan A. , Banerji Aleena , Corel Blanka , Clark Sunday , Camargo Carlos A.
Published: March 2010

OBJECTIVE:

We sought to establish the frequency of receiving >1 dose of epinephrine in children who present to the emergency department (ED) with food-related anaphylaxis.

PATIENTS AND METHODS:

We performed a medical chart review at Boston hospitals of all children presenting to the ED for food-related acute allergic reactions between January 1, 2001, and December 31, 2006. We focused on causative foods, clinical presentations, and emergency treatments.

RESULTS:

Through random sampling and appropriate weighting, the 605 reviewed cases represented a study cohort of 1255 patients. These patients had a median age of 5.8 years (95% confidence interval [CI]: 5.3–6.3), and the cohort was 62% male. A variety of foods provoked the allergic reactions, including peanuts (23%), tree nuts (18%), and milk (15%). Approximately half (52% [95% CI: 48–57]) of the children met diagnostic criteria for food-related anaphylaxis. Among those with anaphylaxis, 31% received 1 dose and 3% received >1 dose of epinephrine before their arrival to the ED. In the ED, patients with anaphylaxis received antihistamines (59%), corticosteroids (57%), epinephrine (20%). Over the course of their reaction, 44% of patients with food-related anaphylaxis received epinephrine, and among this subset of patients, 12% (95% CI: 9–14) received >1 dose. Risk factors for repeat epinephrine use included older age and transfer from an outside hospital. Most patients (88%) were discharged from the hospital. On ED discharge, 43% were prescribed self-injectable epinephrine, and only 22% were referred to an allergist.

CONCLUSIONS:

Among children with food-related anaphylaxis who received epinephrine, 12% received a second dose. Results of this study support the recommendation that children at risk for food-related anaphylaxis carry 2 doses of epinephrine.
Redefining the Role of Intestinal Microbes in the Pathogenesis of Necrotizing Enterocolitis
Authors: Morowitz Michael J. , Poroyko Valeriy , Caplan Michael , Alverdy John , Liu Donald C.
Published: March 2010

Neonatal necrotizing enterocolitis (NEC) remains an important cause of morbidity and mortality among very low birth weight infants. It has long been suspected that intestinal microbes contribute to the pathogenesis of NEC, but the details of this relationship remain poorly understood. Recent advances in molecular biology and enteric microbiology have improved our ability to characterize intestinal microbes from infants with NEC and from healthy unaffected newborns. The lack of diversity within the neonatal intestine makes it possible to study gut microbial communities at a high level of resolution not currently possible in corresponding studies of the adult intestinal tract. Here, we summarize clinical and laboratory evidence that supports the hypothesis that NEC is a microbe-mediated disorder. In addition, we detail recent technologic advances that may be harnessed to perform high-throughput, comprehensive studies of the gut microbes of very low birth weight infants. Methods for characterizing microbial genotype are discussed, as are methods of identifying patterns of gene expression, protein expression, and metabolite production. Application of these technologies to biological samples from affected and unaffected newborns may lead to advances in the care of infants who are at risk for the unabated problem of NEC.
GaAs HEMT Reliability and Degradation Mechanisms after Long Term Stress Testing
Authors: Douglas Erica Ann , Cheney David P. , Chen Ke Hung P. , Chang Chih-Yang P. , Leu Lii-Cherng P. , Gila Brent P. , Abernathy Cammy R. , Pearton Stephen J.
Published: March 2010

GaAs based metamorphic and pseudomorphic high electron mobility transistors (HEMTs) under DC and thermal stress were studied. InAlAs/InGaAs MHEMTs grown on GaAs substrates were stressed at a drain voltage bias of 2.7V for 36 hours as well as thermally stressed at 250°C for 36 hours. Under both stress conditions, the drain current density decreased about 12.5%. The gate current, however, increased more after the thermal storage as opposed to DC bias. Reaction of the Ohmic contact with the underlying semiconductor was the main cause of degradation after thermal stressing. Transmission electron microscopy verified that gate sinking occurred in devices that underwent DC bias stressing. InGaAs pHEMTs that received a 1000 hour lifetime stress test from a commercial vendor showed similar degradation as virgin devices when stressed under DC bias for 24 hours. Virgin devices that were thermally stressed while undergoing DC bias showed minimal degradation up to 120°C, but exhibited catastrophic failure at 140°C.
Strain Induced Stoppage of the Emission Peak Blueshift of Annealed Bilayer Quantum Dot Structures Separated by Thin Spacer
Authors: Sengupta Saumya , Halder Nilanjan , Chakrabarti Subhananda
Published: March 2010

We have investigated the effect of post-growth rapid thermal annealing (RTA) at different temperature on two InAs/GaAs bilayer quantum dots samples with different spacer thicknesses (7.5nm and 8.5nm). It is found that when RTA temperature gradually increases, there is usual blue shift of ground state emission peak wavelength for the sample having thinner spacer but for the other sample the emission peak sustains at same peak wavelength position upto a higher annealing temperature. The dots inside the sample with less spacer thickness dissolute much earlier (beyond 700°C annealing temperature) in comparison to the other sample. The structural and optical characterization has been done by cross sectional transmission electron microscope (XTEM) and low temperature photoluminescence (PL) experiments respectively.
Ink Jet Printing Devices and Circuits
Authors: Ready Steven , Arias Ana , Sambandan Sanjiv , Street Robert
Published: March 2010

For several years there have been many efforts to employ ink jet technologies in the fabrication of consumer electronics. The potential of displacing large and expensive pieces of electronic fabrication equipment and processes with seemingly appropriately scaled inexpensive alternatives is attractive. However, of course, the devil is in the details. Feature size, accuracy, registration and materials all have sever impacts on design rules, processing, performance and the types of devices appropriate to the technology. Here we present a look at some of the materials and deposition challenges along with solutions developed at PARC. The discussion will include the defining of printed features >5μm with ±1.5μm drop placement and layer to layer alignment accuracy, the materials characteristics of the generally complex functional fluids of interest required for reliable jetting and device performance. Examples of ink jet fabricated integrated circuits, working displays, imagers and RGB color filters for LCD displays will be shared.
Growth of High Quality c-plane AlN on a-plane Sapphire
Authors: Miyagawa Reina , Wu Jiejun , Miyake Hideto , Hiramatsu Kazumasa
Published: March 2010

c-plane (0001) AlN layers were grown on sapphire (11-20) and (0001) substrates by hydride vapor phase epitaxy (HVPE) and metal-organic vapor phase epitaxy (MOVPE), respectively. The growth temperatures were adjusted from 1430-1500 °C and the reactor pressure was kept constant at 30 Torr. Mirror and flat c-plane AlN were obtained grown on both a-plane and c-plane sapphire. Crystalline quality and surface roughness are improved with increasing growth temperature, detected by high resolution X-ray diffraction (HRXRD) and atomic force microscopy (AFM). The Full widths at half maximum (FWHM) values of (10-12) diffraction are 519 and 1219 arcsec for c-plane AlN grown on a-plane sapphire and c-plane sapphire, respectively. It indicates that a-plane sapphire substrate benefits to decrease dislocations density.
Reliability and Performance of Pseudomorphic Ultraviolet Light Emitting Diodes on Bulk Aluminum Nitride Substrates
Authors: Gibb Shawn R. , Grandusky James R. , Cui Yongjie , Mendrick Mark C. , Schowalter Leo J.
Published: March 2010

Low dislocation density epitaxial layers of AlxGa1-xN can be grown pseudomorphically on c-face AlN substrates prepared from high quality, bulk crystals. Here, we will report on initial characterization results from deep ultraviolet (UV) light emitting diodes (LEDs) which have been fabricated and packaged from these structures. As reported previously, pseudomorphic growth and atomically smooth surfaces can be achieved for a full LED device structure with an emission wavelength between 250 nm and 280 nm.

A benefit of pseudomorphic growth is the ability to run the devices at high input powers and current densities. The high aluminum content AlxGa1-xN (x∼70%) epitaxial layer can be doped n-type to obtain sheet resistances < 200 Ohms/sq/μm due to the low dislocation density. Bulk crystal growth allows for the ability to fabricate substrates of both polar and non-polar orientations. Non-polar substrates are of particular interest for nitride growth because they eliminate electric field due to spontaneous polarization and piezoelectric effects which limit device performance. Initial studies of epitaxial growth on non-polar substrates will also be presented.
Compact and Efficient HFCVD for Electronic Grade Diamond and Related Materials
Authors: Vispute R. , Seiser Andrew , Lee Geun , Dozier Jaurette , Feldman Jeremy , Robinson Lance , Zayac Bradley , Grobicki Alden
Published: March 2010

A compact and efficient hot filament chemical vapor deposition system has been designed for growing electronic-grade diamond and related materials. We report here the effect of substrate rotation on quality and uniformity of HFCVD diamond films on 2” wafers, using two to three filaments with power ranging from 500 to 600 Watt. Diamond films have been characterized using x-ray diffraction, Raman Spectroscopy, scanning electron microscopy and atomic force microscopy. Our results indicate that substrate rotation not only yields uniform films across the wafer, but crystallites grow larger than without sample rotation. Well-faceted microcrystals are observed for wafers rotated at 10 rpm. We also find that the Raman spectrum taken from various locations indicate no compositional variation in the diamond film and no significant Raman shift associated with intrinsic stresses. Results are discussed in the context of growth uniformity of diamond film to improve deposition efficiency for wafer-based electronic applications.
Patterned Growth of Long and Clean Boron Nitride Nanotubes on Substrates
Authors: Lee Chee Huei , Xie Ming , Wang Jiesheng , Cook Russell E. , Yap Yoke Khin
Published: March 2010

For the first time, patterned growth of boron nitride nanotubes (BNNTs) on Si substrates has been achieved by catalytic chemical vapor deposition (CCVD). Following the boron oxide chemical pathway and our growth vapor trapping approach, high quality and quantity BNNTs can be produced. Effective catalysts have been found to facilitate the growth of BNNTs, while some critical parameters of the synthesis have also been identified to control the quality and density. The success of patterned growth of high quality BNNTs not only explains the roles of the effective catalysts during the synthesis process, but could also be of technologically important for future device fabrication.
Effects of Carbon Ion on Glassy Carbon Electrode as Chemical Sensor
Authors: Chhay Bopha , Bowman Lynn , Ila Daryush
Published: March 2010

Glassy polymeric carbon (GPC) is a material commonly used for making electrodes for cyclic voltammetric (CV) and amperometric measurements. Previous work done at Alabama A&M University (AAMU) has shown that high energy ion beams can be used to improve the physical properties of GPC in general. In this work, we fabricated a glassy polymeric carbon electrode and we used carbon ions to activate it. Surface analyses including Raman spectroscopy, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) were performed to compare the changes in surface morphology and structure before and after carbon ion bombardment.
Improvement of Carbon Nanotube Films on SiC formed by Surface Decomposition by Hydrogen Peroxide Purification
Authors: Maruyama Takahiro , Nakahama Fumiya , Naritsuka Shigeya
Published: March 2010

We studied the effects of annealing in H2O2 on the morphologies and structures of “as grown” high-density, well-aligned multi-walled carbon nanotube (MWNT) films formed by surface decomposition of SiC. After annealing in H2O2 solution at 100°C for 3 h, the G/D ratio increased from 1.44 to 2.33, the FWHM of the G band peak became narrower, and a D′ shoulder peak appeared. Transmission electron microscopy (TEM) revealed that the dispersion of MWNTs in dimethylformamide (DMF) solution was improved, suggesting that film impurities were reduced and that damage to the MWNTs was negligible. After annealing for 9 h, the G/D ratio decreased to 1.57, and exfoliation of some MWNTs was observed. In addition, several functional groups such as carboxylic (-COOH) and hydroxyl (-OH) were formed on the surface of the MWNTs. From these results, we conclude that annealing in H2O2 under proper conditions can effectively purify “as grown” MWNT films formed by surface decomposition of SiC.
The Effect of Nanoparticle Coating on the Thermal Conductivity of Nanofluids
Authors: Fornasiero Michael John , Borca-Tasciuc Diana-Andra
Published: March 2010

Nanofluids are engineered colloidal suspensions of nanometer-sized particles in a carrier fluid and are receiving significant attention because of their potential applications in heat transfer area. Theoretical investigations have shown that the enhanced thermal conductivity observed in nanofluids is due to nanoparticle clustering and networking. This provides a low resistance path to the heat flowing through the fluid. However, the surface coating of the nanoparticles, which is often used to provide stable dispersion over the long term, may act as a thermal barrier, reducing the effective thermal conductivity of the nanofluid. Moreover, nanofluids with the same type of nanoparticles may exhibit different effective thermal conductivities, depending upon the thermal properties and thickness of the coating. In this context, thermal conductivity characterization of well dispersed iron oxide nanoparticles with two different surface coatings was carried out employing the transient hot wire technique. The diameter of the iron oxide core was 35 nm and the coatings used were aminosilane and carboxymethyl-dextran (CMX) of 7nm in thickness. Preliminary results suggest that effective thermal conductivity of CMX coated nanoparticle suspensions is slightly higher than that of aminosilane coated nanoparticles. In both cases, the effective thermal conductivity is higher than that predicted by the Maxwell model for composite media.
Temporal response of the optically generated electric field in InAs/GaAs coupled quantum dots
Authors: Wijesundara Kushal C. , Garrido Mauricio , Ramanathan Swati , Stinaff Eric A. , Bracker Allan S. , Gammon Daniel
Published: March 2010

Coupled quantum dots (CQDs) can provide a sensitive probe of the electric field within a device. With non-resonant excitation above the wetting layer (WL) energy, optical generation of an electric field within the CQD structure was observed. By alternating this non-resonant excitation the temporal response of the optically generated electric field was measured. Decay of this field was measured to be on the order of 110-140 μsec whereas the onset of the optically generated electric field was observed to be less than the temporal resolution of our experiment (7.5 μsec). This may provide a means for fast, non-contact, electric field modulation techniques.
Study of Tb-doped Li2O-LaF3-Al2O3-SiO2 Glasses Containing Silver Nanoparticles
Authors: Pan Zhengda , Crosby A , Obadina O , Ueda A. , Aga R. , Mu R. , Morgan S. H.
Published: March 2010

Tb-doped Li2O-LaF3-Al2O3-SiO2 (LLAS) glasses containing silver were fabricated using melt-quenching technique. Silver nanoparticles (NPs) in glass matrix were confirmed by optical absorption and X-ray diffraction (XRD). The nucleation of silver NPs was controlled by heat-treatment. A broad absorption band peaked at about 420 nm was observed due to surface plasmon resonance (SPR) of the silver NPs. This SPR absorption of silver NPs increases with the time of heat-treatment. Photoluminescence (PL) emission and excitation spectra were measured on Tb-doped LLAS glasses with and without silver NPs. Strong Tb3+ luminescence was observed. For excitation at 325 nm, luminescence of Tb3+ ions increases for the glass containing silver NPs compared to that in the glass without silver NPs. After further heat-treatment at 520 °C for 5 hours, Tb3+ luminescence decreased. Our luminescence results suggest that there are two competitive effects, enhancement and quenching effects, acting on Tb3+ luminescence in the glass containing silver NPs. The enhancement of Tb3+ luminescence is attributed to local field effects due to the excitation of SPR of silver NPs. The quenching effect in the presence of Ag NPs suggests an energy transfer from Tb3+ ions to silver NPs exists, which may provide an additional non-radiative relaxation pathway for the excited Tb3+ ions.
Improvement of the Pt/Graphene Interface Adhesion by Metallic Adatoms for Fuel Cell Applications
Authors: Sen Fatih Gurcag , Qi Yue , Alpas Ahmet T
Published: March 2010

The degradation of carbon supported Pt catalyst used in polymer electrolyte membrane fuel cells is a significant durability problem affected by the agglomeration and detachment of Pt particles from carbon support. The bond between Pt and carbon must be significantly strengthened in order to prevent performance loss. In this work, first principles calculations were carried out in an attempt to understand the role that metallic adatoms play in the enhancement of the Pt/carbon interface adhesion. Metallic adatoms including all first row transition metals as well as Li, Al, Zr, Nb, and Au were inserted into a Pt(111)/graphene interface. The work of separation required to break the interface between Pt-adatom or carbon-adatom bond was then calculated for each configuration, revealing that the carbon-adatom bond was weaker than the Pt-adatom bond, making it easier to break the interface from the carbon-adatom bond side. While Sc, Ti, Zr, and Nb displayed strong binding to both Pt and graphene surfaces, at the Pt/graphene interface, the bond with graphene was weakened. The strength of the Pt-adatom bond was proportional to the amount of charge transferred from the adatom to the graphene. Co, Ni and V were the most promising metals for strengthening the Pt/graphene interface. These metals donated charges that were distributed evenly between carbon and Pt and formed strong covalent bonds with carbon and moderate bonding to Pt.