bluuebunny/crossref_metadata_2025 huggingface dataset:
A better channel coding for a Link‐16 waveform in pulsed‐noise interference
Authors: Kao Chi‐Han
Published: September 2012

Link‐16 is a tactical data link currently used by North Atlantic Treaty Organization (NATO) countries, the United States and its allies. The Link‐16 waveform features Reed–Solomon codes for channel coding, cyclic code‐shift keying for 32‐ary baseband symbol modulation, minimum‐shift keying for waveform modulation, and frequency hopping for transmission security. In addition to the original errors‐only decoding of Reed–Solomon codes, both an errors‐and‐erasures decoding (EED) and a special concatenated coding are proposed in this paper to determine a better channel coding scheme for a Link‐16 waveform with noncoherent detection in the presence of pulsed‐noise interference (PNI). The investigation is first carried out both analytically and by simulation for the original Link‐16 waveform transmitted over AWGN. It is then accomplished analytically for the proposed waveforms in both AWGN and PNI. The results show that EED achieves the best error rate performance for a Link‐16 waveform in both AWGN and PNI when the signal‐to‐noise ratio is relatively small. When both the signal‐to‐noise ratio is sufficiently large and the fraction active time of PNI is small, the proposed concatenated coding outperforms both EED and errors‐only decoding. Copyright © 2012 John Wiley & Sons, Ltd.
The influence of spatiotemporal variability and adaptations to hypoxia on empirical relationships between soil acidity and vegetation
Authors: Cirkel Dirk Gijsbert , Witte Jan‐Philip M. , van Bodegom Peter M. , Nijp Jelmer J. , van der Zee Sjoerd E. A. T. M.
Published: September 2012

Soil acidity is well known to affect the species composition of natural vegetation. The physiological adaptations of plants to soil acidity and related toxicity effects and nutrient deficiencies are, however, complex, manifold and hard to measure. Therefore, generally applicable quantifications of mechanistic plant responses to soil acidity are still not available. An alternative is the semi‐quantitative and integrated response variable ‘indicator value for soil acidity’ (Rm). Although relationships between measured soil pH and Rm from various studies are usually strong, they often show systematic bias and still contain high residual variances. On the basis of a well‐documented national dataset consisting of 91 vegetation plots and a dataset with detailed, within‐plot, pH measurements taken at three periods during the growing season, it is shown that strong spatiotemporal variation of soil pH can be a critical source of systematic errors and statistical noise. The larger part of variation, however, could be explained by the moisture status of plots. For instance, Spearman's rho decreased from 93% for dry plots and 87% for moist plots to 59% for wet plots. The loss of relation between soil pH and Rm in the moderately acid to alkaline range at increasingly wetter plots is probably due to the establishment of aerenchyma‐containing species, which are able to control their rhizosphere acidity. Adaptation to one site factor (oxygen deficit) apparently may induce indifference for other environmental factors (Fe2+, soil pH). For predictions of vegetation response to soil acidity, it is thus important to take the wetness of plots into account. Copyright © 2012 John Wiley & Sons, Ltd.
Polymorphonuclear neutrophils promote dyshesion of tumor cells and elastase‐mediated degradation of E‐cadherin in pancreatic tumors
Authors: Gaida Matthias M. , Steffen Thomas Große , Günther Frank , Tschaharganeh Darjus F. , Felix Klaus , Bergmann Frank , Schirmacher Peter , Hänsch Gertrud M.
Published: September 2012

Pancreatic ductal adenocarcinoma (PDAC) presenting with a micropapillary growth pattern is frequently associated with a prominent neutrophil infiltration into the tumor. The relevance of neutrophil infiltrates for tumor progression, however, is still debated. To gain insight into the role of polymorphonuclear neutrophils (PMNs) in PDAC, we assessed their effect on pancreatic tumor cells grown in vitro as monolayers. Time‐lapse video microscopy showed a PMN‐induced dyshesion of the tumor cells, and subsequent experiments revealed that this dyshesion was due to PMN elastase‐mediated degradation of E‐cadherin, an adhesion molecule that mediates the intercellular contact of the tumor cells. E‐cadherin degradation by elastase or — (for comparison) down‐modulation by specific siRNA, significantly increased the migratory capacity of the pancreatic tumor cells, leading to the hypothesis that PMNs could contribute to the invasive tumor growth. To address this issue, biopsies of patients with PDAC (n = 112) were analyzed. We found that E‐cadherin expression correlated negatively with PMN infiltration, compatible with the notion that E‐cadherin is cleaved by PMN‐derived elastase, which in turn could result in the dispersal of the tumor cells, enhanced migratory capacity and thus invasive tumor growth.
Domino Reactions Initiated by Enantioselective Cu‐Catalyzed Conjugate Addition
Authors: Galeštoková Zuzana , Šebesta Radovan
Published: September 2012

Enantioselective copper‐catalyzed 1,4‐additions of organometallic reagents are useful components of domino reactions. Enolates resulting from such additions readily react with a range of electrophilic reagents, such as aldehydes and acetals, alkyl and allyl halides and halide surrogates, epoxides, imines, nitroalkenes, and α,β‐unsaturated carbonyl compounds. The aim of this review is to give an overview of domino transformations based on Cu‐catalyzed conjugate addition. Special emphasis is placed on the most recent work and also on that utilized in the synthesis of complex target molecules.
A Highly Nucleophilic Multifunctional Chiral Phosphane‐Catalyzed Asymmetric Intramolecular Rauhut–Currier Reaction
Authors: Zhang Xiao‐Nan , Shi Min
Published: September 2012

An asymmetric variant of the intramolecular Rauhut–Currier (RC) reaction can be achieved using a highly nucleophilic multifunctional chiral phosphane; the corresponding cyclopentene and cyclohexene derivatives are produced in moderate to good yields and with good to excellent enantioselectivities.
Evaluation of space–time point process models using super‐thinning
Authors: Clements Robert Alan , Schoenberg Frederic Paik , Veen Alejandro
Published: September 2012

Rescaling, thinning, and superposition are useful methods for the residual analysis of spatial‐temporal point processes. These techniques involve transforming the original point process into a new process that is a homogeneous Poisson process if and only if the fitted model is correct, so that one may inspect the residual process using standard tests for homogeneity as a means of assessing the goodness‐of‐fit of the model. Unfortunately, when the modeled conditional intensity of the original process is volatile, tests of homogeneity performed on residuals on the basis of these three residual methods tend to have low power. For such circumstances, we propose the method of super‐thinning, which combines thinned residuals and superposition. This technique involves the use of a tuning parameter, k, which controls how much thinning and superposition are performed to homogenize the process. The method is applied to the assessment of a parametric space–time point process model for the origin times and epicentral locations of recent major California earthquakes. Copyright © 2012 John Wiley & Sons, Ltd.
Impregnated charcoal cloth for the treatment of air polluted with hydrogen cyanide
Authors: Prasad G.K. , Kumar J. Praveen , Ramacharyulu P.V.R.K. , Singh Beer
Published: September 2012

Impregnated charcoal cloth was prepared by a novel single‐step method using water‐soluble salts such as copper nitrate, silver nitrate, and ammonium heptamolybdate. Impregnation was achieved by using simple, user‐friendly spraying technique. The obtained cloth samples were characterized by nitrogen adsorption technique. Kinetics of hydrogen cyanide adsorption were explored using charcoal cloth impregnated with copper(II), molybdenum(VI), and silver(I) salts. Modified Wheeler equation was used for analyzing adsorption kinetics, and the data were represented as kinetic saturation capacity and kinetic rate constant. Kinetic saturation capacity value was found to decrease from 0.01 to 0.003 g/g as the value of inlet concentration increased from 81 to 365 ppm. Kinetic rate constant value increased from 2018 to 5048 min−1 when the flow rate was increased from 400 to 1000 mL/min, whereas kinetic saturation capacity value was found to be invariant. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 715–720, 2013
Mechanisms to limit higher mode effects in a controlled rocking steel frame. 1: Concept, modelling, and low‐amplitude shake table testing
Authors: Wiebe Lydell , Christopoulos Constantin , Tremblay Robert , Leclerc Martin
Published: September 2012

Controlled rocking steel frames have been proposed as an efficient way to avoid the structural damage and residual deformations that are expected in conventional seismic force resisting systems. Although the base rocking response is intended to limit the force demands, higher mode effects can amplify member design forces, reducing the viability of the system. This paper suggests that seismic forces may be limited more effectively by providing multiple force‐limiting mechanisms. Two techniques are proposed: detailing one or more rocking joints above the base rocking joint and providing a self‐centring energy dissipative (SCED) brace at one or more levels. These concepts are applied to the design of an eight‐storey prototype structure and a shake table model at 30% scale. A simple numerical model that was used as a design tool is in good agreement with frequency characterization and low‐amplitude seismic tests of the shake table model, particularly when multiple force‐limiting mechanisms are active. These results suggest that the proposed mechanisms can enable better capacity design by reducing the variability of peak seismic force demands without causing excessive displacements. Similar results are expected for other systems that rely on a single location of concentrated nonlinearity to limit peak seismic loads. Copyright © 2012 John Wiley & Sons, Ltd.
Joint routing and channel assignment algorithms in cognitive wireless mesh networks
Authors: Zhang Guo‐an , Gu Jin‐yuan , Bao Zhi‐hua , Xu Chen , Zhang Shi‐bing
Published: September 2012

Multiple channels can increase network capacity by transmitting traffic on different channels in an interference area. To resolve the channel interference problem in cognitive wireless mesh networks, first, a new channel assignment algorithm based on hierarchy interference model for the cognitive wireless mesh networks is proposed in this paper. Second, a distributed capacity and interference based channel assignment and routing algorithm is proposed. Third, an efficient channel diversity based channel allocation algorithm is proposed. The main purpose of this channel allocation algorithm is to maintain the channel diversity in the neighborhood channels. Fourth, a novel joint multi‐path routing and channel assignment algorithm based on path crossing is proposed. On the basis of simulations, results show that compared with the link‐based channel allocation algorithm in wireless multi‐channel networks, the new four algorithms have an obvious advantage in the performance of delay and throughput, and the performance of the joint multi‐path routing and channel assignment algorithm is the best. Lastly, a channel merging algorithm is also proposed in the channel constrained situation. Simulation results also show that, after the implementation of the channel merging algorithm, the network average throughput and delay performance have been further improved significantly. Copyright © 2012 John Wiley & Sons, Ltd.
Operation Characteristic Analysis of a Direct Methanol Fuel Cell System Using the Methanol Sensor‐less Control Method
Authors: Chen C. Y. , Chang C. L. , Sung C. C.
Published: September 2012

The application of methanol sensor‐less control in a direct methanol fuel cell (DMFC) system eliminates most of the problems encountered when using a methanol sensor and is one of the major solutions currently used in commercial DMFCs. This study focuses on analyzing the effect of the operating characteristics of a DMFC system on its performance under the methanol sensor‐less control as developed by Institute of Nuclear Energy Research (INER). Notably, the influence of the dispersion of the methanol injected on the behavior of the system is investigated systematically. In addition, the mechanism of the methanol sensor‐less control is investigated by varying factors such as the timing of the injection of methanol, the cathode flow rate, and the anode inlet temperature. These results not only provide insight into the mechanism of methanol sensor‐less control but can also aid in the improvement and application of DMFC systems in portable and low‐power transportation.
Model verification and evaluation of the rich‐split process modification at an Australian‐based post combustion CO2 capture pilot plant
Authors: Cousins Ashleigh , Cottrell Aaron , Lawson Anthony , Huang Sanger , Feron Paul H.M.
Published: September 2012

The CSIRO is involved in three CO2 capture pilot plants operating at different coal‐fired power stations throughout Australia. The most recently completed of these is the Tarong CO2 capture pilot plant located at Tarong power station, Nanango, Queensland. The first phase of the experimental program with this pilot plant included operation with monoethanolamine (MEA). This involved parametric studies, process modifications, and finally implementation of 24 h operation. Operation of the pilot plant has shown MEA to be effective in capturing CO2 from the flue gas from Tarong Power Station. CO2 capture efficiencies of up to 94%, and regeneration energies as low as 3.6 MJ/kgCO2 have been achieved. The design of the pilot plant was completed using a commercially available process modeling software tool. Results obtained from the pilot plant were then compared to the model predictions including temperature, solvent CO2 loading, and CO2 gas concentration profiles through the absorber column. A good match has been obtained between the modeling and pilot plant data, verifying the software can be used to predict the performance of the pilot plant when operating on MEA. During this project, the rich‐split process modification was also evaluated. The results suggest that the rich‐split modification can achieve some reduction in reboiler duty and a considerable reduction in the condenser duty. The amount of reduction is dependent on plant design, particularly the efficiency of the lean/rich heat exchanger. © 2012 Society of Chemical Industry and John Wiley & Sons, Ltd
Network‐based analysis reveals stronger local diffusion‐based connectivity and different correlations with oral language skills in brains of children with high functioning autism spectrum disorders
Authors: Li Hai , Xue Zhong , Ellmore Timothy M. , Frye Richard E. , Wong Stephen T.C.
Published: September 2012

Neuroimaging has uncovered both long‐range and short‐range connectivity abnormalities in the brains of individuals with autism spectrum disorders (ASD). However, the precise connectivity abnormalities and the relationship between these abnormalities and cognition and ASD symptoms have been inconsistent across studies. Indeed, studies find both increases and decreases in connectivity, suggesting that connectivity changes in the ASD brain are not merely due to abnormalities in specific connections, but rather, due to changes in the structure of the network in which the brain areas interact (i.e., network topology). In this study, we examined the differences in the network topology between high‐functioning ASD patients and age and gender matched typically developing (TD) controls. After quantitatively characterizing the whole‐brain connectivity network using diffusion tensor imaging (DTI) data, we searched for brain regions with different connectivity between ASD and TD. A measure of oral language ability was then correlated with the connectivity changes to determine the functional significance of such changes. Whole‐brain connectivity measures demonstrated greater local connectivity and shorter path length in ASD as compared to TD. Stronger local connectivity was found in ASD, especially in regions such as the left superior parietal lobule, the precuneus and angular gyrus, and the right supramarginal gyrus. The relationship between oral language ability and local connectivity within these regions was significantly different between ASD and TD. Stronger local connectivity was associated with better performance in ASD and poorer performance in TD. This study supports the notion that increased local connectivity is compensatory for supporting cognitive function in ASD. Hum Brain Mapp 35:396–413, 2014. © 2012 Wiley Periodicals, Inc.
Tumors of the cervical sympathetic chain—Diagnosis and management
Authors: Langerman Alexander , Rangarajan Sanjeet V. , Athavale Sanjay M. , Pham Michelle Q. , Sinard Robert J. , Netterville James L.
Published: September 2012

Background

Tumors originating from the cervical sympathetic chain are uncommon but important entities in the differential diagnosis of parapharyngeal space masses.

Methods

We conducted a retrospective review of patients presenting with tumors of the cervical sympathetic chain.

Results

Twenty‐four patients presented between 1994 and 2010. Presenting symptoms were dysphagia (n = 7.29%), neck mass (n = 7.29%), throat fullness (n = 4.17%), and Horner syndrome (n = 2.8%). Although radiologic images showed classic lateral displacement of the carotid arteries in 10 patients (42%), in 9 patients (38%) the radiologic findings demonstrated splaying of the carotid arteries similar to carotid body tumor, and in 5 patients (20%), the findings were indeterminate. Twenty‐one patients underwent surgical removal of the tumors with pathology revealing 10 paragangliomas, 10 schwannomas, and 1 neurofibroma. Horner (57%) and first‐bite (33%) syndromes were the most common complications.

Conclusions

Although anterolateral displacement of the carotids is suggestive of a sympathetic tumor, absence of these findings does not rule out this entity. To this end, we have included in this review a guide to preoperative radiologic diagnosis of parapharyngeal space lesions. © 2012 Wiley Periodicals, Inc. Head Neck, 2013
Surgical management of inverted papilloma: Approaching a new standard for surgery
Authors: Carta Filippo , Blancal Jean‐Philippe , Verillaud Benjamin , Tran Hugo , Sauvaget Elisabeth , Kania Romain , Herman Philippe
Published: September 2012

Background

Inverted papilloma surgery is currently performed primarily with an endoscopic approach, a technique that has a recurrence rate of 12%. However, a recent study reported a recurrence rate of 5% with a strategy based on subperiosteal dissection of the tumor, with limited indications for using an external approach. The aim of this work was to evaluate whether different teams using the same surgical concepts could reproduce the excellent results that were recently reported.

Methods

This study is a retrospective chart review of 71 consecutive patients with inverted papilloma who were treated during the last 10 years.

Results

In all, 80% of the patients were treated using a purely endoscopic approach. The mean follow‐up period was 31.6 months. The recurrence rate was 3.3% for cases with at least a 12‐month follow‐up.

Conclusions

This work confirms the results described in recent literature and further supports transnasal endoscopic surgery to manage inverted papilloma. © 2012 Wiley Periodicals, Inc. Head Neck 35: 1415–1420, 2013
Inflammatory and regulatory T cells contribute to a unique immune microenvironment in tumor tissue of colorectal cancer patients
Authors: Girardin Adam , McCall John , Black Michael A. , Edwards Francesca , Phillips Vicky , Taylor Edward S , Reeve Anthony E , Kemp Roslyn A
Published: September 2012

Colorectal cancer is one of the five leading causes of cancer mortality worldwide. The mechanisms of pathogen clearance, inflammation and regulation by T cells in the healthy bowel are also important in controlling tumor growth. The majority of studies analyzing T cells and their relationship to colorectal tumor growth have focused on individual T cell markers or gene clusters and thus the complexity of the T cell response contributing to the growth of the tumor is not clear. We have studied the T cells in colorectal cancer patients and have defined a unique T cell signature for colorectal tumor tissue. Using a novel analytical flow cytometric approach in concert with confocal microscopy, we have shown that the tumor has a lower frequency of effector T cells (CD69+), but a higher frequency of both regulatory (CD25hi Foxp3+) and inflammatory T cells (IL‐17+) compared with associated nontransformed bowel tissue. We have also identified minor populations of T cells expressing conventional markers of both inflammatory and regulatory T cells (CD4+IL‐17+Foxp3+) in the tumor tissue. These cells may represent intermediate populations or they may dictate an inflammatory versus regulatory function in surrounding T cells. Together, these data describe an immune microenvironment in colorectal cancer unique to the tumor tissue and distinct from the surrounding healthy bowel tissue, and this distinct environment is reflected by a gradient of T cells expressing markers of multiple T cell populations. These findings may be used to improve diagnosis and prognosis of colorectal cancer patients.
Nanoelectroablation of human pancreatic carcinoma in a murine xenograft model without recurrence
Authors: Nuccitelli Richard , Huynh Joanne , Lui Kaying , Wood Ryan , Kreis Mark , Athos Brian , Nuccitelli Pamela
Published: September 2012

We have identified an effective nanoelectroablation therapy for treating pancreatic carcinoma in a murine xenograft model. This therapy initiates apoptosis in a nonthermal manner by applying low energy electric pulses 100 ns long and 30 kV/cm in amplitude to the tumor. We first identified the minimum pulse number required for complete ablation by treating 30 tumors. We found that the minimum number of pulses required to ablate the tumor with a single treatment is between 250 and 500 pulses. We settled on a single application of either 500 or 1,000 pulses to treat pancreatic carcinomas in 19 NIH‐III mice. Seventeen of the 19 treated tumors exhibited complete regression without recurrence. Three mice died of unknown causes within 3 months after treatment but 16 lived for 270–302 days at which time we sacrificed them for histological analysis. In the 17 untreated controls, the tumor grew so large that we had to sacrifice all of them within 4 months.
Soluble c‐Met protein as a susceptible biomarker for gastric cancer risk: A nested case‐control study within the Korean Multicenter Cancer Cohort
Authors: Yang Jae Jeong , Yang Ji Hyun , Kim Jungkon , Ma Seung Hyun , Cho Lisa Y. , Ko Kwang‐Pil , Shin Aesun , Choi Bo Youl , Kim Hyun Ja , Han Dong Soo , Eun Chang Soo , Song Kyu Sang , Kim Yong Sung , Chang Soung‐Hoon , Shin Hai‐Rim , Kang Daehee , Yoo Keun‐Young , Park Sue K.
Published: September 2012

This study was conducted to evaluate the relevance of the soluble form of c‐Met protein, a truncated form of the c‐Met membrane receptor involved in the CagA pathway, as a potential biomarker for gastric cancer. Among 290 gastric cancer case‐control sets selected from the Korean Multicenter Cancer Cohort, the plasma concentrations of soluble c‐Met protein were measured with enzyme‐linked immunosorbent assays. Using analysis of variance and covariance models with age, sex, smoking, Helicobacter pylori infection, and CagA seropositivity, the mean concentrations of soluble c‐Met protein between cases and controls were compared. To evaluate the association between gastric cancer and a c‐Met protein level, odds ratios and 95% confidence intervals were estimated using conditional logistic regression models. Interactions between CagA‐related genes and the soluble c‐Met protein concentration were also investigated. The overall median plasma concentration of soluble c‐Met among cases was significantly lower than those of controls (1.390 vs. 1.610 ng/mL, p < 0.0001). Closer to the onset of gastric cancer, the soluble c‐Met protein level decreased linearly in a time‐dependent manner (p for trend = 0.0002). The combined effects between the CagA‐related genes and the soluble c‐Met protein concentration significantly intensified risks for gastric cancer. Restricted analyses including cases that had been diagnosed within 1 year after entering the cohort had a fair degree of ability (area under the receiver operating characteristic curve of 0.73–0.77) to discriminate gastric cancer cases from normal controls. Our findings demonstrate the potential of the soluble form of c‐Met protein as a novel biomarker for gastric cancer. The beneficial effects of a high soluble c‐Met concentration in human plasma are strongly supported.
Preparation and characterization of collagen‐nanohydroxyapatite biocomposite scaffolds by cryogelation method for bone tissue engineering applications
Authors: Rodrigues Sandra C. , Salgado Christiane L. , Sahu Abhishek , Garcia Monica P. , Fernandes Maria H. , Monteiro Fernando J.
Published: September 2012

Recent efforts of bone repair focus on development of porous scaffolds for cell adhesion and proliferation. Collagen‐nanohydroxyapatite (HA) scaffolds (70:30; 50:50; and 30:70 mass percentage) were produced by cryogelation technique using 1‐ethyl‐3‐(3‐dimethyl aminopropyl) carbodiimide hydrochloride/N‐hydroxysuccinimide as crosslinking agents. A pure collagen scaffold was used as control. Morphology analysis revealed that all cryogels had highly porous structure with interconnective porosity and the nanoHA aggregates were randomly dispersed throughout the scaffold structure. Chemical analysis showed the presence of all major peaks related to collagen and HA in the biocomposites and indicated possible interaction between nanoHA aggregates and collagen molecules. Porosity analysis revealed an enhancement in the surface area as the nanoHA percentage increased in the collagen structure. The biocomposites showed improved mechanical properties as the nanoHA content increased in the scaffold. As expected, the swelling capacity decreased with the increase of nanoHA content. In vitro studies with osteoblasts cells showed that they were able to attach and spread in all cryogels surfaces. The presence of collagen‐nanoHA biocomposites resulted in higher overall cellular proliferation compared to pure collagen scaffold. A statistically significant difference between collagen and collagen‐nanoHA cryogels was observed after 21 day of cell culture. These innovative collagen‐nanoHA cryogels could have potentially appealing application as scaffolds for bone regeneration. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
Water‐stable electrospun collagen fibers from a non‐toxic solvent and crosslinking system
Authors: Jiang Qiuran , Reddy Narendra , Zhang Simeng , Roscioli Nicholas , Yang Yiqi
Published: September 2012

Cytocompatible and water‐stable ultrafine collagen fibers were electrospun by dissolving collagen in a low corrosive ethanol–water solvent and crosslinked by citric acid (CA) with glycerol as the crosslinking extender. Conventional solvents used for electrospinning of collagen either cause denaturation or contain more than 50% salt potentially leading to poor mechanical properties and water stability of the scaffolds. Collagen scaffolds have to be modified by techniques, such as, crosslinking to overcome the limitations in strength and stability. However, the existing crosslinking methods are either cytotoxic or ineffective. In this research, a benign ethanol‐water solvent system and an extender‐aided CA crosslinking method were developed. The native collagen conformation was retained after electrospinning, and the dry/wet strengths and water stability of fibers were substantially enhanced after crosslinking. The crosslinked electrospun scaffolds could maintain their fibrous structure for up to 30 days in phosphate‐buffered saline at 37°C. Cells exhibited better attachment and growth on the CA crosslinked collagen fibers than on the glutaraldehyde crosslinked scaffolds. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
Improving the packing density of calcium phosphate coating on a magnesium alloy for enhanced degradation resistance
Authors: Kannan M. Bobby
Published: September 2012

In this study, an attempt was made to improve the packing density of calcium phosphate (CaP) coating on a magnesium alloy by tailoring the coating solution for enhanced degradation resistance of the alloy for implant applications. An organic solvent, ethanol, was added to the coating solution to decrease the conductivity of the coating solution so that hydrogen bubble formation/bursting reduces during the CaP coating process. Experimental results confirmed that ethanol addition to the coating solution reduces the conductivity of the solution and also decreases the hydrogen evolution/bubble bursting. In vitro electrochemical experiments, that is, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization showed that CaP coating produced in 30% (v/v) ethanol containing coating solution (3E) exhibits significantly higher degradation resistance (i.e., ∼50% higher polarization resistance and ∼60% lower corrosion current) than the aqueous solution coating. Scanning electron microscope (SEM) analysis of the coatings revealed that the packing of 3E coating was denser than that of aqueous coating, which can be attributed to the lower hydrogen evolution in the former than in the latter. Further increase in the ethanol content in the coating solution was not beneficial; in fact, the coating produced in 70% (v/v) ethanol containing solution (7E) showed degradation resistance much inferior to that of the aqueous coating, which is due to low thickness of 7E coating. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
Synthesis of (−)‐3‐Carene‐2,5‐dione via Allylic Oxidation of (+)‐3‐Carene
Authors: Sun Xiaoling , Zhao Xiaoyan , Jiang Ying , Xu Bochun
Published: September 2012

Activated carbon‐supported CuCl2 (CuCl2/AC) is a heterogeneous catalyst for the liquid‐phase selective allylic oxidation of (+)‐3‐carene with tert‐butyl hydroperoxide (TBHP) and O2 to produce (−)‐3‐carene‐2,5‐dione. The possible reaction mechanism and the effects of different factors on the allylic oxidation were investigated. The optimal conditions are as follows: reaction temperature, 45 °C; molar ratio of CuCl2 to (+)‐3‐carene, 1%; volume ratio of (+)‐3‐carene to TBHP, 1:3; and reaction time, 12 h. Under the optimal conditions, the conversion of (+)‐3‐carene reached 100%, whereas the selectivity for (−)‐3‐carene‐2,5‐dione reached 78%. The CuCl2/AC catalyst was characterized via X‐ray diffraction, and the chemical structure of the target compound was identified via infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, mass spectrometry, and optical analysis.
A Theoretical Investigation of the Decomposition Reactions of Ethyl Formate in the S0 State
Authors: Chou Yung‐Ching
Published: September 2012

This study revisits the stability of the possible conformations and the decomposition reactions of ethyl formate in the S0 state using the (U)MP2, MP4SDTQ, CCSD(T), and (U)B3LYP methods with various basis sets. The transition states of the decomposition channels to HCOOH + C2H4, CO + CH3CH2OH, CH2O + CH3CHO, HCOH + CH3CHO, C2H6 + CO2, and H2 + CH2CHOCHO are determined. The microcanonical rate constants derived from the RRKM theory are calculated for each of the decomposition reactions. The high‐pressure limit rate constants are calculated for the decomposition channels to HCOOH + C2H4, CO + CH3CH2OH, and CH2O + CH3CHO.
Pore‐forming technology and performance of MEA for direct methanol fuel cells
Authors: Liu Gui‐Cheng , Wang Yi‐Tuo , Zhang Jing , Wang Meng , Zhang Chao‐Jie , Wang Xin‐Dong
Published: September 2012

BACKGROUND: The commercialization of DMFCs is seriously restricted by its relatively low power density. Lots of work has been concentrated on catalysts with high activity, the optimization of flow path design, development of new kinds of proton exchange membrane and modification of Nafion membrane. Meanwhile, very few reports have involved the structure optimization of the membrane electrode assembly (MEA). To improve the performance of direct methanol fuel cells (DMFCs), the catalyst layer (CL) structures of anode and cathode were optimized by utilizing ammonium carbonate as pore forming agent.

RESULTS: The polarization curves showed that in catalyst slurry the optimal content of ammonium carbonate was 50 wt%, and the DMFC performance was enhanced from 75.65 mW cm−2 to 167.42 mW cm−2 at 55 °C and 0.2 MPa O2. Electrochemical impedance spectroscopy and electrochemical active surface area (EASA) testing revealed that the improved performance of optimized MEAs could be mainly attributed to the increasing EASA and the enhanced mass transfer rate of CLs. But poor methanol crossover limited the performance enhancement of MEAs with porous anodes.

CONCLUSION: With regard to improving cell performance, this pore‐forming technology is better applied to the cathode catalyst layer to improve its structure rather than the anode catalyst layer. © 2012 Society of Chemical Industry
Resolution of N‐hydroxymethyl vince lactam catalyzed by lipase in organic solvent
Authors: Xun Erna , Wang Jiaxin , Zhang Hong , Chen Ge , Yue Hong , Zhao Jimin , Wang Lei , Wang Zhi
Published: September 2012

BACKGROUND: The enantiomers of N‐hydroxymethyl vince lactam are important intermediates during the synthesis of chiral drugs. The preparation of its single enantiomer can be performed through enzymatic resolution. The aim of this work is to obtain (1S, 4R)‐N‐hydroxymethyl vince lactam with high enantiomeric purity via lipase‐catalyzed enantioselective transesterification in organic solvents. To achieve this, effects of various reaction conditions (including lipase sources, acyl donor, substrate molar ratio, organic solvent, temperature, and water activity) on the enzyme activity as well as enantioselectivity were investigated.

RESULTS: The results of the study showed that the enantiopreference for all the selected enzymes was (4S, 1R)‐N‐hydroxymethyl vince lactam in enantioselective transesterification of racemic N‐hydroxymethyl vince lactam. Under the selected optimum conditions, the highest enantioselectivity (E = 33.8) was obtained with a higher enzyme activity (20.3 µmol g−1 min−1) for Mucor miehei lipase (MML) when vinyl valerate was used as the acyl donor. Besides, the remained (1S, 4R)‐N‐hydroxymethyl vince lactam with high enantiomeric purity (ee > 99%) was obtained when the conversion was about 60%.

CONCLUSION: The results obtained clearly demonstrated potential for industrial application of lipase in resolution of N‐hydroxymethyl vince lactam through enantioselective transesterification. © 2012 Society of Chemical Industry
Cognitive enhancement and neuroprotection by catechin‐rich oil palm leaf extract supplement
Authors: Mohamed Suhaila , Lee Ming Tan , Jaffri Juliana Md
Published: September 2012

BACKGROUND: Catechin‐rich oil palm (Elaeis guineensis) leaf extract (OPLE) has good cardiovascular and phytoestrogenic properties. The OPLE (0.5 g day−1) was supplemented to young, healthy, adult human volunteers, and their cognitive learning abilities were compared to placebo‐controlled groups (N = 15). Their short‐term memories, spatial visualisations, processing speeds, and language skills, were assessed over 2 months by cognitive tests computer programs.

RESULTS: Relative to the controls, volunteers taking OPLE had improved (P < 0.05) short‐term memory, after 1 month of intervention which became highly significant (P < 0.005) after 2 months. The spatial visualisation ability and processing speed improved (P < 0.05) after 2 months consumption. The dietary OPLE showed neuroprotection in nitric oxide‐deficient rats. The mechanisms involved systemic and cellular modulations that eventually enhance neuron survival. The longer the duration of OPLE consumption, the more significant was the enhancement, as shown for short‐term memory.

CONCLUSION: This is the first report on the cognitive‐enhancing effects of dietary OPLE in humans. The computer‐assisted cognitive tests were simple, low in cost, errors and man hours, and hence are better than conventional cognitive test methods. In rats, the equivalent OPLE dose showed brain antioxidant enzymes modulating properties and neuroprotection under nitric oxide deficiency, with possibly neurogenesis in normal rats. This supported the effects in humans. © 2012 Society of Chemical Industry
Removal of endotoxins from plasmid DNA: Analysis of aggregative interaction of mobile divalent metal cations with endotoxins and plasmid DNA
Authors: Ongkudon Clarence M. , Hodges Emma , Murphy Kathleen , Danquah Michael K.
Published: September 2012

Endotoxin lipopolysaccharide removal from plasmid DNA‐based vaccine remains a very challenging task for bioprocess engineers. This paper examined the potential use and advantages of divalent cation (Zn2+, Ca2+, Mg2+) induced aggregation as a plasmid DNA purification method for lipopolysaccharide removal. Analysis of zeta potential, hydrodynamic size, percentage of aggregation; UV‐Vis spectroscopy and electron microscopy were performed to determine the optimal cation for preferential aggregation of lipopolysaccharide over plasmid DNA. The results from the hydrodynamic size analysis showed that the addition of Zn2+ resulted in the maximum theoretical number of lipopolysaccharide molecules per aggregate particle. Dynamic light scattering analysis showed that plasmid DNA aggregates formed a larger maximum hydrodynamic size when it was treated with Ca2+ than the other two cations. The Km value for lipopolysaccharide‐Zn2+ was substantially low (0.28 M) and considerably large (>2 M) for plasmid DNA‐Zn2+. Scatchard plots for plasmid DNA cations showed positive slopes indicating that there was a minimum concentration of plasmid DNA or cations before a significant aggregation occurred. This work concluded that Zn2+ had the most preferential aggregative interaction with lipopolysaccharide compared to Mg2+ and Ca2+.
Efficient protocol for isolation and purification of different soyasaponins from soy hypocotyls
Authors: Zhao Dayun , Yan Mingxia , Huang Yuai , Sun Xiangjun
Published: September 2012

Soyasaponins are naturally occurring triterpenoid glycosides associated with many biological activities. The aim of the present study was to develop an effective method for isolation and purification of differently glycosylated, acetylated, and 2,3‐dihydro‐2,5‐dihydroxy‐6‐methyl‐4H‐pyran‐4‐one (DDMP)‐conjugated soyasaponins from soy hypocotyls. Both gel filtration using Sephadex LH‐20 chromatography (Amersham Pharmacia Biotech AB; elution phase: methanol, flow rate: 3.0 mL/min, sample loading: 60 mg) and high‐speed countercurrent chromatography (stationary phase: n‐butanol–acetic acid (5.0%, v/v), mobile phase: water flow rate: 3.0 mL/min, sample loading: 100 mg) could effectively fractionate isoflavones and soyasaponins from the crude extract with yield of soyasaponin complexes 20.5 mg and 22.3 mg, respectively. After fractionation, the soyasaponin complexes could be purified further using preparative HPLC to separate individuals. A total of nine soyasaponins, triacetyl soyasaponin Ab (yield 1.55%, HPLC purity >98%), Aa (2.68%, >99%), Ab (18.53%, >98%), Ae (0.85%, >98%), Ba (0.63%, >91%), Af (1.12%, >85%), Bb (3.45%, >98%) and Be (0.59%, >76.8%) were obtained. DDMP‐conjugated groups, αg (2.06%, >85%), βg (7.59%, >85%), and γg (0.29%, >85%) that were very labile even in mild conditions, were also collected. The method described here can be used as an effective protocol to separate different soyasaponins occurring in the original sample.
Computer‐assisted design and rapid prototype modeling in microvascular mandible reconstruction
Authors: Hanasono Matthew M. , Skoracki Roman J.
Published: September 2012

Objectives/Hypothesis:

To evaluate the use of computer‐assisted design and rapid prototype modeling to improve the speed and accuracy of mandibular reconstruction.

Study Design:

Case‐control study.

Methods:

Between 2005 and 2011, 38 subjects underwent fibula free flap mandibular reconstruction using computer‐assisted design and rapid prototype modeling. Titanium plates were prebent using the models prior to surgery. Direct plate bending on the native mandible to accurately restore occlusion would not have been possible in 11 patients with exophytic tumors, nine patients with pathologic fractures, and 10 patients with a prior segmental mandibulectomy. Computer‐generated cutting guides were utilized to facilitate fibular osteotomies.

Results:

The mean operative time for subjects was 8.8 ± 1.0 hours compared to the mean operative time defect‐matched control group, for whom computer‐assisted design and models were not used, of 10.5 ± 1.4 hours (P = .0006). Comparison of the preoperative and postoperative mandibles demonstrated that the mean change in position of selected bony landmarks (condyles, gonions, and gnathion) was less in the subject group than in the control group (4.11 ± 3.09 mm vs. 6.92 ± 5.64 mm, respectively; P = .001) Comparison of postoperative mandibles with preoperative virtual plans showed a mean deviation of 2.40 ± 2.06 mm from planned fibular segment lengths and 3.51 ± 2.69° from planned angles between fibular segments.

Conclusions:

Computer‐assisted design and rapid prototype modeling have the potential to increase the speed and accuracy of mandibular reconstruction. We believe these technologies are particularly useful for cases in which the original architecture of the mandible has been distorted or destroyed. Laryngoscope, 2013
Projected future increase in aging hepatitis C virus–infected liver transplant candidates: A potential effect of hepatocellular carcinoma
Authors: Biggins Scott W. , Bambha Kiran M. , Terrault Norah A. , Inadomi John , Shiboski Stephen , Dodge Jennifer L. , Gralla Jane , Rosen Hugo R. , Roberts John P.
Published: September 2012

In the United States, the peak hepatitis C virus (HCV) antibody prevalence of 4% occurred in persons born in the calendar years 1940-1965. The goal of this study was to examine observed and projected age-specific trends in the demand for liver transplantation (LT) among patients with HCV-associated liver disease stratified by concurrent hepatocellular carcinoma (HCC). All new adult LT candidates registered with the Organ Procurement and Transplantation Network for LT between 1995 and 2010 were identified. Patients who had primary, secondary, or text field diagnoses of HCV with or without HCC were identified. There were 126,862 new primary registrants for LT, and 52,540 (41%) had HCV. The number of new registrants with HCV dramatically differed by the age at calendar year, and this suggested a birth cohort effect. When the candidates were stratified by birth year in 5-year intervals, the birth cohorts with the highest frequency of HCV were as follows (in decreasing order): 1951-1955, 1956-1960, 1946-1950, and 1941-1945. These 4 birth cohorts, spanning from 1941 to 1960, accounted for 81% of all new registrants with HCV. A 4-fold increase in new registrants with HCV and HCC occurred between the calendar years 2000 and 2010 in the 1941-1960 birth cohorts. By 2015, we anticipate that an increasing proportion of new registrants with HCV will have HCC and be ≥60 years old (born in or before 1955). In conclusion, the greatest demand for LT due to HCV-associated liver disease is occurring among individuals born between 1941 and 1960. This demand appears to be driven by the development of HCC in patients with HCV. During the coming decade, the projected increase in the demand for LT from an aging HCV-infected population will challenge the transplant community to reconsider current treatment paradigms. Liver Transpl, 2012. © 2012 AASLD.
Antimicrobial Hydantoin‐grafted Poly(ε‐caprolactone) by Ring‐opening Polymerization and Click Chemistry
Authors: Tan Licheng , Maji Samarendra , Mattheis Claudia , Chen Yiwang , Agarwal Seema
Published: September 2012

Novel degradable and antibacterial polycaprolactone‐based polymers are reported in this work. The polyesters with pendent propargyl groups are successfully prepared by ring‐opening polymerization and subsequently used to graft antibacterial hydantoin moieties via click chemistry by a copper(I)‐catalyzed azide‐alkyne cycloaddition reaction. The well‐controlled chemical structures of the grafted copolymers and its precursors are verified by FT‐IR spectroscopy, NMR spectroscopy, and GPC characterizations. According to the DSC and XRD results, the polymorphisms of these grafted copolymers are mostly changed from semicrystalline to amorphous depending on the amount of grafted hydantoin. Antibacterial assays are carried out with Bacillus subtilis and two strains of Escherichia coli and show fast antibacterial action.

magnified image
Effect of Degree of Branching on Properties of Photosensitive Nanoparticles as Drug‐Delivery Carriers
Authors: Shi Dongjian , Matsusaki Michiya , Chen Mingqing , Akashi Mitsuru
Published: September 2012

Hyperbranched copolymers with different degrees of branching (DBs), poly(3,4‐dihydroxycinnamic acid)‐co‐poly(4‐hydroxycinnamic acid) (PCA), were prepared by polycondensation. Amphiphilic PCA–DTT copolymers were prepared by grafting dithiothreitiol (DTT) into PCA by the Michael addition. PCA–DTT nanoparticles were self‐assembled by additional water into a DMSO solution of PCA–DTT. The diameter and photoresponsivity of the PCA–DTT nanoparticles were influenced by the DB, and they increased with increasing the DB. Bovine serum albumin (BSA) as a model protein was successfully encapsulated into the PCA–DTT nanoparticles, and the release behavior of BSA was affected by the DB in PBS. These biodegradable and photoresponsive nanoparticles would be useful as functional carriers for drug delivery systems.
Biological, Chemical, and Electronic Applications of Nanofibers
Authors: Nguyen Luong T. H. , Chen Shilin , Elumalai Naveen K. , Prabhakaran Molamma P. , Zong Yun , Vijila Chellappan , Allakhverdiev Suleyman I. , Ramakrishna Seeram
Published: September 2012

With their high‐surface‐to‐volume ratio, nanofibers have been postulated to increase interactions between nanofibrous materials and targeted substrates, which are helpful to overcome many obstacles and enhance the efficiency in a diverse number of applications. Over the past decade, many studies have been published on the fabrication of nanofibers and their applications in various fields. In this review, novel biological, chemical, and electrical characteristics of nanofibers as well as their recent status and achievements in medicine, chemistry, and electronics are analyzed. It is found that nanofibers can induce fast regeneration of many tissues/organs in medical applications and improve the efficiency of many chemical and electronics applications.

magnified image
Ceramic fibre reinforced refractory castables for very high temperature superplastic forming
Authors: Mazzoni A. , Bernhart G. , Cutard T.
Published: September 2012

In the frame of the development of very high temperature die material solutions, two grades of alumina based ceramic fibres with a diameter close to 12 μm have been investigated as reinforcement solutions for an andalusite refractory castable. High temperature mechanical tests were performed up to 1200°C in four‐point bending conditions: rupture tests at high temperature and anisothermal creep tests. After testing, microstructural and rupture surface were observed in order to get information on deformation mechanisms and rupture processes. Results show that significant mechanical improvement were obtained up to 1100°C when compared to non reinforced refractory castables.