bluuebunny/crossref_metadata_2025 huggingface dataset:
Organoclay‐reinforced compatible blends of polypropylene with an amorphous polyamide
Authors: Aranburu Nora , Eguiazábal José I.
Published: December 2013

New nanocomposite materials based on a modified polypropylene (PP) and an amorphous polyamide (aPA)/organoclay nanocomposite were obtained in the melt state. Two aPA contents and organoclay contents in the dispersed phase that varied from 0 to 10 wt% were studied. All the fully exfoliated organoclay remained in the dispersed and minor aPA phase. While adhesive fracture occurred, the interfacial tension was rather low; this is believed to be due to the presence of PP subparticles within the dispersed aPA, creating a large contact surface area. The organoclay in the dispersed phase was seen to be just as capable of increasing the elasticity modulus as when it is dispersed in the matrix. This occurs as long as there is a minimum level of interfacial adhesion, and offers new versatility in the design of nanocomposite materials. POLYM. ENG. SCI., 54:2762–2769, 2014. © 2013 Society of Plastics Engineers
Improving the properties of polylactic acid by blending with low molecular weight polylactic acid‐g‐natural rubber
Authors: Thepthawat Apicha , Srikulkit Kawee
Published: December 2013

The low molecular weight (Mw) polylactic acid‐g‐natural rubber (PLA‐g‐NR) was synthesized by grafting the maleated natural rubber (MNR) with low molecular weight PLA at a weight ratio of 1:1 in toluene at 80°C. Two types of MNR (MNR10 and MNR20) having anhydride moieties of 10 and 20 wt%, respectively, were prepared. The reaction was followed by IR analysis. Next, the obtained PLA‐g‐NR was blended with pristine PLA using a twin‐screw extruder at PLA to PLA‐g‐NR weight ratios of 90:10, 80:20, 70:30, and 60:40 followed by compression to obtain specimens for testing. In case of 10 wt% PLA‐g‐NR having MNR10, it was found that blending of PLA with PLA‐g‐NR resulted in a 200% improvement in impact strength and twofold percent elongation at break (flexibility). Further SEM analysis confirmed that PLA‐g‐NR was compatible with PLA matrix. In contrast, NR was present as disperse particles which exhibited poor adhesion to PLA. From these findings, it was also found that PLA‐g‐NR was capable of improving the properties of PLA more than NR due to the fact that it exhibited higher compatibility. POLYM. ENG. SCI., 54:2770–2776, 2014. © 2013 Society of Plastics Engineers
A renewable agricultural waste material for the synthesis of the novel thermal stability epoxy resins
Authors: Ding Na , Wang Xiaofeng , Tian Yumei , Yang Liu , Chen Hongzhuo , Wang Zichen
Published: December 2013

Lignin has received wide attention due to the enormous renewable supply and potential use of this inexpensive organic raw material. We used straw lignin to partly replace bisphenol A for preparing epoxy resins. This process not only greatly reduces the environmental pollution caused by lignin, but also decreases the production cost of epoxy resins. The lignin coming from agricultural waste was modified by Mannich reaction. At the beginning, we would get the mixture after diethanolamine was reacted with formaldehyde for 2 hr. Then the modified lignin was prepared by adding dropwise the mixture into lignin solution. The contents of active groups, including phenolic hydroxyl and hydroxymethyl, in modified lignin by Mannich reaction had been improved effectively. In addition, lignin‐based epoxy resins which we prepared by modified lignin have good thermal stability. POLYM. ENG. SCI., 54:2777–2784, 2014. © 2013 Society of Plastics Engineers
Antibacterial materials: structure–bioactivity relationship of epoxy–amine resins containing quaternary ammonium compounds covalently attached
Authors: Mondrzyk Adam , Fischer Julian , Ritter Helmut
Published: December 2013

Bifunctional aminoalkyldimethylpropylammonium salts (N‐(3‐aminopropyl)‐N,N‐dimethylpentylammonium chloride, N‐(3‐aminopropyl)‐N,N‐dimethyloctylammonium chloride, N‐(3‐aminopropyl)‐N,N‐dimethyldecylammonium chloride, N‐(3‐aminopropyl)‐N,N‐dimethyldodecylammonium chloride) are synthesized and their structure‐dependent antibacterial effect against Gram‐negative Escherichia coli and Gram‐positive Lactococcus lactis is investigated. To this end, resins prepared from bisphenol A diglycidyl ether (2,2‐bis[4‐(glycidyloxy)phenyl]propane) and diethylenetriamine (2,2′‐diaminodiethylamine) as matrix and the bifunctional aminoalkyldimethylpropylammonium salts in a ratio of 6 mol% compared to epoxy components are used. A dependence of antibacterial effect on alkyl chain length of the quaternary ammonium compounds is observed for both species. Furthermore, resins with N‐(3‐aminopropyl)‐N,N‐dimethyldecylammonium chloride in varying concentrations up to 16 mol% for both organisms show a concentration‐dependent antibacterial effect of the quaternary ammonium salt. The antibacterial materials are characterized by differential scanning calorimetry, infrared spectroscopy and rheological studies. © 2013 Society of Chemical Industry
Quantitative proteomics of fractionated membrane and lumen exosome proteins from isogenic metastatic and nonmetastatic bladder cancer cells reveal differential expression of EMT factors
Authors: Jeppesen Dennis Kjølhede , Nawrocki Arkadiusz , Jensen Steffen Grann , Thorsen Kasper , Whitehead Bradley , Howard Kenneth A. , Dyrskjøt Lars , Ørntoft Torben Falck , Larsen Martin R. , Ostenfeld Marie Stampe
Published: December 2013

Cancer cells secrete soluble factors and various extracellular vesicles, including exosomes, into their tissue microenvironment. The secretion of exosomes is speculated to facilitate local invasion and metastatic spread. Here, we used an in vivo metastasis model of human bladder carcinoma cell line T24 without metastatic capacity and its two isogenic derivate cell lines SLT4 and FL3, which form metastases in the lungs and liver of mice, respectively. Cultivation in CLAD1000 bioreactors rather than conventional culture flasks resulted in a 13‐ to 16‐fold increased exosome yield and facilitated quantitative proteomics of fractionated exosomes. Exosomes from T24, SLT4, and FL3 cells were partitioned into membrane and luminal fractions and changes in protein abundance related to the gain of metastatic capacity were identified by quantitative iTRAQ proteomics. We identified several proteins linked to epithelial–mesenchymal transition, including increased abundance of vimentin and hepatoma‐derived growth factor in the membrane, and casein kinase II α and annexin A2 in the lumen of exosomes, respectively, from metastatic cells. The change in exosome protein abundance correlated little, although significant for FL3 versus T24, with changes in cellular mRNA expression. Our proteomic approach may help identification of proteins in the membrane and lumen of exosomes potentially involved in the metastatic process.
Proteomic differences between microvascular endothelial cells and the EA.hy926 cell line forming three‐dimensional structures
Authors: Ma Xiao , Sickmann Albert , Pietsch Jessica , Wildgruber Robert , Weber Gerhard , Infanger Manfred , Bauer Johann , Grimm Daniela
Published: December 2013

Proteomic changes of two types of human endothelial cells (ECs) were determined and compared to morphological alterations occurring during the scaffold‐free in vitro formation of 3D structures resembling vascular intimas. The EA.hy926 cell line and human microvascular ECs (HMVECs) were cultured on a random positioning machine or static on ground (normal gravity) for 5 and 7 days, before their morphology was examined and their protein content was analysed by MS after free‐flow electrophoretic separation. A total of 1175 types of proteins were found in EA.hy926 cells and 846 in HMVEC forming 3D structures faster than the EA.hy926 cells. Five hundred and eighty‐four of these kinds of proteins were present in both types of cells. They included a number of metabolic enzymes, of structure‐related and stress proteins. Comparing proteins of EA.hy926 cells growing either adherently on ground or in 3D aggregates on the random positioning machine revealed that ribosomal proteins were enhanced, while tubes are formed and various components of 26S proteasomes remained prevalent in static normal gravity control cells only. The fast developing tube‐like 3D structures of HMVEC suggested a transient augmentation of ribosomal proteins during the 3D assembling of ECs.
Signatures of n→π* interactions in proteins
Authors: Newberry Robert W. , Bartlett Gail J. , VanVeller Brett , Woolfson Derek N. , Raines Ronald T.
Published: December 2013

The folding of proteins is directed by a variety of interactions, including hydrogen bonding, electrostatics, van der Waals' interactions, and the hydrophobic effect. We have argued previously that an n→π* interaction between carbonyl groups be added to this list. In an n→π* interaction, the lone pair (n) of one carbonyl oxygen overlaps with the π* antibonding orbital of another carbonyl group. The tendency of backbone carbonyl groups in proteins to engage in this interaction has consequences for the structures of folded proteins that we unveil herein. First, we employ density functional theory to demonstrate that the n→π* interaction causes the carbonyl carbon to deviate from planarity. Then, we detect this signature of the n→π* interaction in high‐resolution structures of proteins. Finally, we demonstrate through natural population analysis that the n→π* interaction causes polarization of the electron density in carbonyl groups and detect that polarization in the electron density map of cholesterol oxidase, further validating the existence of n→π* interactions. We conclude that the n→π* interaction is operative in folded proteins.
Resistance to antibiotics targeted to the bacterial cell wall
Authors: Nikolaidis I. , Favini‐Stabile S. , Dessen A.
Published: December 2013

Peptidoglycan is the main component of the bacterial cell wall. It is a complex, three‐dimensional mesh that surrounds the entire cell and is composed of strands of alternating glycan units crosslinked by short peptides. Its biosynthetic machinery has been, for the past five decades, a preferred target for the discovery of antibacterials. Synthesis of the peptidoglycan occurs sequentially within three cellular compartments (cytoplasm, membrane, and periplasm), and inhibitors of proteins that catalyze each stage have been identified, although not all are applicable for clinical use. A number of these antimicrobials, however, have been rendered inactive by resistance mechanisms. The employment of structural biology techniques has been instrumental in the understanding of such processes, as well as the development of strategies to overcome them. This review provides an overview of resistance mechanisms developed toward antibiotics that target bacterial cell wall precursors and its biosynthetic machinery. Strategies toward the development of novel inhibitors that could overcome resistance are also discussed.
Functional analysis of glaucoma data
Authors: Hosseini‐Nasab Mohammad , Mirzaei K. Zahra
Published: December 2013

We refer glaucoma to a category of eye disorders often associated with a dangerous buildup of intraocular pressure (IOP), which can damage the eyes’ optic nerve that transmits visual information to the brain. Because IOP changes over time, it is a function of time, and it is an advantage that we analyze the phenomenon using functional data analysis. In this paper, we treat the data related to the IOP of 35 patients with right eye glaucoma, collected in Rasul‐e‐Akram Hospital at Tehran, Iran, over the years 2007–2011. We shall explore the structure of the data in search of the features that describe them, and find the characteristics that give a comprehensible presentation of the structure of the variability in the data. We extract patterns of variation in the data by using a generalization of the smoothed functional principal component analysis to obtain the main factors causing glaucoma and then determine their importance. We also explore the correlation patterns between the IOP of right and left eyes, and then model the left eye IOP of the glaucoma patients at each time on the basis of their right eye IOP in a previous interval of time. We can use the model to predict the values of the former variable by using the latter one in a previous time interval. Copyright © 2013 John Wiley & Sons, Ltd.
Psychological Resilience, Affective Mechanisms and Symptom Burden in a Tertiary‐care Sample of Patients with Fibromyalgia
Authors: McAllister Samantha J. , Vincent Ann , Hassett Afton L. , Whipple Mary O. , Oh Terry H. , Benzo Roberto P. , Toussaint Loren L.
Published: December 2013

Research demonstrates that patients with fibromyalgia who have higher positive and lower negative affect have lower symptom burden. Affect has been shown to be associated with resilience. This study examined the relationship between affect, resilience and fibromyalgia symptom burden in a clinical sample of patients with fibromyalgia. We hypothesized that (a) positive and negative affect would be associated with fibromyalgia symptom burden; (b) resilience would be associated with positive and negative affect; (c) resilience would be associated with fibromyalgia symptom burden; and (d) the connection between resilience and fibromyalgia symptom burden would be mediated by both positive and negative affect. A sample of 858 patients with fibromyalgia completed questionnaires. Mediation modelling revealed statistically significant direct effects of resilience on fibromyalgia symptom burden (β = −0.10, P < 0.001) and statistically significant indirect effects of resilience on fibromyalgia symptom burden through affect (β = −0.36, P < 0.001), suggesting that both resilience and affect influence fibromyalgia symptom burden. Our results suggest that improving affect through resiliency training could be studied as a modality for improving fibromyalgia symptom burden. Copyright © 2013 John Wiley & Sons, Ltd.
Beyond institutional voids: Business groups, incomplete markets, and organizational form
Authors: Manikandan K. S. , Ramachandran J.
Published: December 2013

We extend the “institutional voids” perspective on business groups by examining the value‐adding potential of two of the characteristic features of business groups: their diverse portfolio and multi‐entity organizational form. We maintain that portfolio diversity affords affiliates privileged access to opportunities hidden by incomplete strategic factor markets. We hypothesize that the multi‐entity organizational form enables superior sensing and seizing of these growth opportunities by affiliate firms. We further suggest that, in the context of institutional reforms, these characteristics strengthen business group affiliates' ability to capitalize on the expanded set of opportunities made available by the reform program. Empirical analyses on a sample of Indian firms over the period 1994–2010 support our hypotheses. Implications for theory and future directions are discussed. Copyright © 2013 John Wiley & Sons, Ltd.
Simplicity‐first model‐based plug‐in development
Authors: Naujokat Stefan , Neubauer Johannes , Lamprecht Anna‐Lena , Steffen Bernhard , Jörges Sven , Margaria Tiziana
Published: December 2013

In this article, we present our experience with over a decade of strict simplicity orientation in the development and evolution of plug‐ins. The point of our approach is to enable our graphical modeling framework jABC to capture plug‐in development in a domain‐specific setting. The typically quite tedious and technical plug‐in development is shifted this way from a programming task to the modeling level, where it can be mastered also by application experts without programming expertise. We show how the classical plug‐in development profits from a systematic domain‐specific API design and how the level of abstraction achieved this way can be further enhanced by defining adequate building blocks for high‐level plug‐in modeling. As the resulting plug‐in models can be compiled and deployed automatically, our approach decomposes plug‐in development into three phases where only the realization phase requires plug‐in‐specific effort. By using our modeling framework jABC, this effort boils down to graphical, tool‐supported process modeling. Furthermore, we support the automatic completion of process sketches for executability. All this will be illustrated along the most recent plug‐in‐based evolution of the jABC framework, which witnessed quite some bootstrapping effects. Copyright © 2013 John Wiley & Sons, Ltd.
Pylorus‐Resecting Pancreaticoduodenectomy Offers Long‐Term Outcomes Similar to Those of Pylorus‐Preserving Pancreaticoduodenectomy: Results of a Prospective Study
Authors: Kawai Manabu , Tani Masaji , Hirono Seiko , Okada Ken‐ichi , Miyazawa Motoki , Yamaue Hiroki
Published: December 2013

Background

We showed in a previous study that pylorus‐resecting pancreaticoduodenectomy (PrPD), which divides the stomach adjacent to the pylorus ring, preserves more than 95 % of the stomach and significantly reduced the incidence of delayed gastric emptying (DGE) compared with pylorus‐preserving pancreaticoduodenectomy (PpPD). However, long‐term outcomes of PrPD and the adverse effect of early postoperative DGE on long‐term outcomes remain unclear.

Methods

A total of 130 patients enrolled in a previous study were followed for 24 months after surgery. Primary endpoint was whether PrPD is a better surgical procedure than PpPD regarding long‐term outcomes.

Results

Weight loss > grade 2 (Common Terminology Criteria for Adverse Events, Version 4.03) at 24 months after surgery was significantly better in group PrPD (16.2 %) than in group PpPD (42.2 %) (p = 0.011). Nutritional status and late postoperative complications were similar for the two groups. The incidence of weight loss > grade 2 at 24 months was 63.6 % in DGE patients with DGE and 25.3 % in non‐DGE patients (p = 0.010). Tmax (time to peak 13CO2 content in 13C‐acetate breath test) at 24 months in DGE patients was significantly delayed compared with that in non‐DGE patients (27.9 ± 22.7 vs. 16.5 ± 10.1 min, p = 0.023). Serum albumin level at 24 months was higher in non‐DGE patients than in those with DGE (3.7 ± 0.6 vs. 4.1 ± 0.4 g/dl, p = 0.013).

Conclusions

PrPD offers long‐term outcomes similar to those of PpPD. DGE may be associated with weight loss and poor nutritional status in patients with long‐term outcomes.
Enhancing Surgical Performance Outcomes Through Process‐driven Care: A Systematic Review
Authors: Pucher Philip H. , Aggarwal Rajesh , Singh Pritam , Darzi Ara
Published: December 2013

Background

Recent evidence has demonstrated the variability in quality of postoperative care, as measured by rates of failure to rescue (FTR). The identification of structure‐ and process‐related factors affecting the quality of postoperative care is the first step towards understanding and improving outcomes. The aim of this review is to review current evidence for structure and process factors affecting postoperative care.

Methods

A systematic review was conducted. Studies were selected that examined structure or process variables affecting FTR rates and postoperative outcomes. Quality analysis with Jadad and Newcastle–Ottawa scales was conducted and poor‐quality studies were excluded.

Results

Thirty‐seven studies were included in final analysis. Of these, 23 were related to enhanced recovery protocols in seven surgical specialties. Twenty‐one of these 23 studies reported decreases in length of stay. Six studies also reported decreases in morbidity. No studies reported increases in stay duration or morbidity. Of the 16 studies that examined other structural and process factors, the strongest evidence was for the association between nursing ratios and FTR rates. The effects of hospital size, resources, and subspecialist care processes were less clear.

Conclusion

Process‐led care represents a clear, evidence‐based approach that can be integrated on a local scale, without necessitating major structural or organisational change, to improve outcomes and may also be cost effective. To foster success, process improvement must be driven on a local level and backed up by appropriate understanding, education, and multidisciplinary involvement.
Enhanced ethyl caproate production of Chinese liquor yeast by overexpressing EHT1 with deleted FAA1
Authors: Chen Yefu , Li Feng , Guo Jian , Liu Guangxin , Guo Xuewu , Xiao Dongguang
Published: December 2013

The fruity odor of Chinese liquor is largely derived from ester formation. Ethyl caproate, an ethyl ester eliciting apple-like flavor, is one of the most important esters in the strong aromatic Chinese liquor (or Luzhou-flavor liquor), which is the most popular and best-selling liquor in China. In the traditional fermentation process, ethyl caproate in strong aromatic liquor is mainly produced by aroma-producing yeast, bacteria, and mold with high esterification abilities in a mud pit at later fermentation stages at the expense of both fermentation time and grains rather than by the ethanol-fermenting yeast Saccharomyces cerevisiae. To increase the production of ethyl caproate by Chinese liquor yeast (S. cerevisiae AY15) and shorten the fermentation period, we constructed a recombinant strain EY15 by overexpressing EHT1 (encoding ethanol hexanoyl transferase), in which FAA1 (encoding acyl-CoA synthetases) was deleted. In liquid fermentation of corn hydrolysate and solid fermentation of sorghum, ethyl caproate production by EY15 was remarkably increased to 2.23 and 2.83 mg/L, respectively, which were 2.97- and 2.80-fold higher than those of the parental strain AY15. Furthermore, an increase in ethyl octanoate (52 and 43 %) and ethyl decanoate (61 and 40 %) production was observed. The differences in fermentation performance between EY15 and AY15 were negligible. This study resulted in the creation of a promising recombinant yeast strain and introduced a method that can be used for the clean production of strong aromatic Chinese liquor by ester-producing S. cerevisiae without the need for a mud pit.
Influence of polysorbate 80 and cyclopropane fatty acid synthase activity on lactic acid production by Lactobacillus casei ATCC 334 at low pH
Authors: Broadbent J R , Oberg T S , Hughes J E , Ward R E , Brighton C , Welker D L , Steele J L
Published: December 2013

Lactic acid is an important industrial chemical commonly produced through microbial fermentation. The efficiency of acid extraction is increased at or below the acid’s pKa (pH 3.86), so there is interest in factors that allow for a reduced fermentation pH. We explored the role of cyclopropane synthase (Cfa) and polysorbate (Tween) 80 on acid production and membrane lipid composition in Lactobacillus casei ATCC 334 at low pH. Cells from wild-type and an ATCC 334 cfa knockout mutant were incubated in APT broth medium containing 3 % glucose plus 0.02 or 0.2 % Tween 80. The cultures were allowed to acidify the medium until it reached a target pH (4.5, 4.0, or 3.8), and then the pH was maintained by automatic addition of NH4OH. Cells were collected at the midpoint of the fermentation for membrane lipid analysis, and media samples were analyzed for lactic and acetic acids when acid production had ceased. There were no significant differences in the quantity of lactic acid produced at different pH values by wild-type or mutant cells grown in APT, but the rate of acid production was reduced as pH declined. APT supplementation with 0.2 % Tween 80 significantly increased the amount of lactic acid produced by wild-type cells at pH 3.8, and the rate of acid production was modestly improved. This effect was not observed with the cfa mutant, which indicated Cfa activity and Tween 80 supplementation were each involved in the significant increase in lactic acid yield observed with wild-type L. casei at pH 3.8.
Algicidal metabolites produced by Bacillus sp. strain B1 against Phaeocystis globosa
Authors: Zhao Ling , Chen Lina , Yin Pinghe
Published: December 2013

The bloom of Phaeocystis globosa has broken out frequently in the coastal areas of China in recent years, which has led to substantial economic losses. This study shows that Bacillus sp. strain B1, which was previously identified by our group, is effective in regulating P. globosa by excreting active metabolites. Heat stability, pH stability and molecular weight range of the algicidal compounds from strain B1 were measured and the results demonstrated that the algicidal activities of these compounds were not affected by pH or temperature variation. The algicidal compounds extracted with methanol were isolated and purified by ODS-A column chromatography and HPLC. The algicidal compounds corresponding to peaks 2–5 eluted from HPLC were further analysed by quadrupole time-of-flight mass spectrometry (Q-TOF–MS). PeakView™ Software determined the compounds corresponding to peaks 2–5 to be l-histidine, o-tyrosine, N-acetylhistamine and urocanic acid on the basis of the accurate mass information, the isotopic pattern and MS–MS spectra. Furthermore, these compounds were also able to eliminate Skeletonema costatum, Prorocentrum donghaiense and Heterosigma akashiwo. This is the first report of bacteria-derived algicidal compounds being identified only by Q-TOF–MS and PeakView™ Software, and these compounds may be used as the constituents of algicides in the future.
Stability of Essential Fatty Acids and Formation of Nutritionally Undesirable Compounds in Baking and Shallow Frying
Authors: Hrncirik Karel , Zeelenberg Manon
Published: December 2013

During cooking oils and fats are exposed to high temperatures that may affect the nutritional quality of foods that are prepared in this way. Concerns have been raised about the degradation of polyunsaturated fatty acids and the formation of potentially harmful compounds during deep frying, but relatively little is known about these changes in other cooking processes. In the present study sponge cakes and fried potatoes were prepared via standardised baking and shallow frying procedures by using different oils and fats (sunflower oil, rapeseed oil, various margarines or butter). The effect of cooking on the retention of two essential fatty acids (linoleic acid and α‐linolenic acid) and the formation of trans fatty acids (TFA) and polymerised triacylglycerols (PTG) was evaluated by analyzing fat extracted from the cooked food. It was found that over 95 % of essential fatty acids were retained upon completion of both cooking techniques. The formation of TFA was not significant. Polymerisation was noticeable only in shallow frying, although the final levels of PTG were negligible (<1.3 %). Overall, in contrast to deep frying, oil‐based media high in polyunsaturated fatty acids seem to be a good alternative for domestic cooking techniques as they increase the nutritional value of the prepared food.
Postbuckling behaviors of nanorods including the effects of nonlocal elasticity theory and surface stress
Authors: Thongyothee Chawis , Chucheepsakul Somchai
Published: December 2013

This paper is concerned with postbuckling behaviors of nanorods subjected to an end concentrated load. One end of the nanorod is clamped while the other end is fixed to a support that can slide in the slot. The governing equation is developed from static equilibrium and geometrical conditions by using the exact curvature corresponding to the elastica theory. The nonlocal elasticity, the effect of surface stress, and their combined effects are taken into account in Euler–Bernoulli beam theory. Differential equations in this problem can be solved numerically by using the shooting-optimization technique for the postbuckling loads and the buckled configurations. The results show that nanorods with the nonlocal elasticity effect undergo increasingly large deformation while the effect of surface stress in combination with nonlocal elasticity decreases the deflection of nanorods under the same postbuckling load.
Automation of a high-speed imaging setup for differential viscosity measurements
Authors: Hurth C. , Duane B. , Whitfield D. , Smith S. , Nordquist A. , Zenhausern F.
Published: December 2013

We present the automation of a setup previously used to assess the viscosity of pleural effusion samples and discriminate between transudates and exudates, an important first step in clinical diagnostics. The presented automation includes the design, testing, and characterization of a vacuum-actuated loading station that handles the 2 mm glass spheres used as sensors, as well as the engineering of electronic Printed Circuit Board (PCB) incorporating a microcontroller and their synchronization with a commercial high-speed camera operating at 10 000 fps. The hereby work therefore focuses on the instrumentation-related automation efforts as the general method and clinical application have been reported earlier [Hurth et al., J. Appl. Phys. 110, 034701 (2011)]. In addition, we validate the performance of the automated setup with the calibration for viscosity measurements using water/glycerol standard solutions and the determination of the viscosity of an “unknown” solution of hydroxyethyl cellulose.
Total reflection infrared spectroscopy of water-ice and frozen aqueous NaCl solutions
Authors: Walker Rachel L. , Searles Keith , Willard Jesse A. , Michelsen Rebecca R. H.
Published: December 2013

Liquid-like and liquid water at and near the surface of water-ice and frozen aqueous sodium chloride films were observed using attenuated total reflection infrared spectroscopy (ATR-IR). The concentration of NaCl ranged from 0.0001 to 0.01 M and the temperature varied from the melting point of water down to 256 K. The amount of liquid brine at the interface of the frozen films with the germanium ATR crystal increased with salt concentration and temperature. Experimental spectra are compared to reflection spectra calculated for a simplified morphology of a uniform liquid layer between the germanium crystal and the frozen film. This morphology allows for the amount of liquid observed in an experimental spectrum to be converted to the thickness of a homogenous layer with an equivalent amount of liquid. These equivalent thickness ranges from a nanometer for water-ice at 260 K to 170 nm for 0.01 M NaCl close to the melting point. The amounts of brine observed are over an order of magnitude less than the total liquid predicted by equilibrium thermodynamic models, implying that the vast majority of the liquid fraction of frozen solutions may be found in internal inclusions, grain boundaries, and the like. Thus, the amount of liquid and the solutes dissolved in them that are available to react with atmospheric gases on the surfaces of snow and ice are not well described by thermodynamic equilibrium models which assume the liquid phase is located entirely at the surface.
Propensity approach to nonequilibrium thermodynamics of a chemical reaction network: Controlling single E-coli β-galactosidase enzyme catalysis through the elementary reaction steps
Authors: Das Biswajit , Banerjee Kinshuk , Gangopadhyay Gautam
Published: December 2013

In this work, we develop an approach to nonequilibrium thermodynamics of an open chemical reaction network in terms of the elementary reaction propensities. The method is akin to the microscopic formulation of the dissipation function in terms of the Kullback-Leibler distance of phase space trajectories in Hamiltonian system. The formalism is applied to a single oligomeric enzyme kinetics at chemiostatic condition that leads the reaction system to a nonequilibrium steady state, characterized by a positive total entropy production rate. Analytical expressions are derived, relating the individual reaction contributions towards the total entropy production rate with experimentally measurable reaction velocity. Taking a real case of Escherichia coli β-galactosidase enzyme obeying Michaelis-Menten kinetics, we thoroughly analyze the temporal as well as the steady state behavior of various thermodynamic quantities for each elementary reaction. This gives a useful insight in the relative magnitudes of various energy terms and the dissipated heat to sustain a steady state of the reaction system operating far-from-equilibrium. It is also observed that, the reaction is entropy-driven at low substrate concentration and becomes energy-driven as the substrate concentration rises.
Synchrotron-based far infrared study of the rotation-vibration-inversion spectrum of silacyclobutane below 500 cm−1: The ν29 and ν30 bands
Authors: Chen Ziqiu , van Wijngaarden Jennifer
Published: December 2013

Fourier transform spectra of the four-membered heterocycle silacyclobutane (c-C3H8Si) were recorded in the far infrared region from 100 to 500 cm−1 with a maximum resolution of 0.000959 cm−1 using synchrotron radiation from the Canadian Light Source. The two fundamental bands observed in this region correspond to motions best described as the out-of-plane modes related to ring puckering (ν30) at ∼158 cm−1 and SiH2 rocking (ν29) at ∼410 cm−1. Both bands exhibit complex, dense spectral patterns that arise from ring inversion tunneling of the puckered SCB ring through a planar (C2v) intermediate configuration. Analysis of these patterns revealed rotation-vibration transitions between states of the same inversion symmetry as well as rotation-vibration-inversion transitions that connect states of different inversion symmetry. Infrared ground state combination differences from 1871 pairs of P and R branch transitions were used to accurately determine the spectroscopic parameters for the tunneling-doubled ground state based on a broad range of quantum levels. With the ground state energy levels well-determined, 8255 infrared transitions were assigned and analyzed to derive the band centers, rotational and centrifugal distortion constants for the inversion split ν29 and ν30 vibrational states. Comparison with the band centers predicted via DFT (B3LYP) and MP2 calculations [6-311++G(2d,2p)] suggests that anharmonic corrections found via perturbation theory typically agree within 2% when compared with the observed spectrum of SCB.
A united event grand canonical Monte Carlo study of partially doped polyaniline
Authors: Byshkin M. S. , Correa A. , Buonocore F. , Di Matteo A. , Milano G.
Published: December 2013

A Grand Canonical Monte Carlo scheme, based on united events combining protonation/deprotonation and insertion/deletion of HCl molecules is proposed for the generation of polyaniline structures at intermediate doping levels between 0% (PANI EB) and 100% (PANI ES). A procedure based on this scheme and subsequent structure relaxations using molecular dynamics is described and validated. Using the proposed scheme and the corresponding procedure, atomistic models of amorphous PANI-HCl structures were generated and studied at different doping levels. Density, structure factors, and solubility parameters were calculated. Their values agree well with available experimental data. The interactions of HCl with PANI have been studied and distribution of their energies has been analyzed. The procedure has also been extended to the generation of PANI models including adsorbed water and the effect of inclusion of water molecules on PANI properties has also been modeled and discussed. The protocol described here is general and the proposed United Event Grand Canonical Monte Carlo scheme can be easily extended to similar polymeric materials used in gas sensing and to other systems involving adsorption and chemical reactions steps.
Aspects of the inverse problem for the Toda chain
Authors: Kozlowski K. K.
Published: December 2013

We generalize Babelon's approach to equations in dual variables so as to be able to treat new types of operators which we build out of the sub-constituents of the model's monodromy matrix. Further, we also apply Sklyanin's recent monodromy matrix identities so as to obtain equations in dual variables for yet other operators. The schemes discussed in this paper appear to be universal and thus, in principle, applicable to many models solvable through the quantum separation of variables.
Development of fast cooling pulsed magnets at the Wuhan National High Magnetic Field Center
Authors: Peng Tao , Sun Quqin , Zhao Jianlong , Jiang Fan , Li Liang , Xu Qiang , Herlach Fritz
Published: December 2013

Pulsed magnets with fast cooling channels have been developed at the Wuhan National High Magnetic Field Center. Between the inner and outer sections of a coil wound with a continuous length of CuNb wire, G10 rods with cross section 4 mm × 5 mm were inserted as spacers around the entire circumference, parallel to the coil axis. The free space between adjacent rods is 6 mm. The liquid nitrogen flows freely in the channels between these rods, and in the direction perpendicular to the rods through grooves provided in the rods. For a typical 60 T pulsed magnetic field with pulse duration of 40 ms, the cooling time between subsequent pulses is reduced from 160 min to 35 min. Subsequently, the same technology was applied to a 50 T magnet with 300 ms pulse duration. The cooling time of this magnet was reduced from 480 min to 65 min.
A reduced moment-based model for oxygen precipitation in silicon
Authors: Trzynadlowski Bart C. , Dunham Scott T.
Published: December 2013

A model for the precipitation of oxygen and associated dislocation loops in Czochralski-grown silicon is presented. Beginning with kinetic rate equations describing the growth and dissolution of oxide precipitates, a reduced model based on the moments of the precipitate size distribution is developed and validated against experimental data. The complete model source code is provided. Comparisons with the full, rate equation-based model show that the reduced version is comparably accurate, while requiring significantly less computational power. The formation of dislocation loops due to silicon interstitial ejection during precipitate growth is modeled using a simple, moment-based approach. An analysis of the sensitivity of the oxygen model to parameters is included.
A 350 mK, 9 T scanning tunneling microscope for the study of superconducting thin films on insulating substrates and single crystals
Authors: Kamlapure Anand , Saraswat Garima , Ganguli Somesh Chandra , Bagwe Vivas , Raychaudhuri Pratap , Pai Subash P.
Published: December 2013

We report the construction and performance of a low temperature, high field scanning tunneling microscope (STM) operating down to 350 mK and in magnetic fields up to 9 T, with thin film deposition and in situ single crystal cleaving capabilities. The main focus lies on the simple design of STM head and a sample holder design that allows us to get spectroscopic data on superconducting thin films grown in situ on insulating substrates. Other design details on sample transport, sample preparation chamber, and vibration isolation schemes are also described. We demonstrate the capability of our instrument through the atomic resolution imaging and spectroscopy on NbSe2 single crystal and spectroscopic maps obtained on homogeneously disordered NbN thin film.
Self-focusing of a high current density ion beam extracted with concave electrodes in a low energy region around 150 eV
Authors: Hirano Y. , Kiyama S. , Koguchi H. , Sakakita H.
Published: December 2013

Spontaneous self-focusing of ion beam with high current density (Jc ∼ 2 mA/cm2, Ib ∼ 65 mA) in low energy region (∼150 eV) is observed in a hydrogen ion beam extracted from an ordinary bucket type ion source with three electrodes having concave shape (acceleration, deceleration, and grounded electrodes). The focusing appears abruptly in the beam energy region over ∼135–150 eV, and the Jc jumps up from 0.7 to 2 mA/cm2. Simultaneously a strong electron flow also appears in the beam region. The electron flow has almost the same current density. Probably these electrons compensate the ion space charge and suppress the beam divergence.
Photoluminescence, recombination rate, and gain spectra in optically excited n-type and tensile strained germanium layers
Authors: Virgilio M. , Manganelli C. L. , Grosso G. , Schroeder T. , Capellini G.
Published: December 2013

We theoretically investigate the optical properties of photo-excited biaxially strained intrinsic and n-type doped Ge semi-infinite layers using a multi-valley effective mass model. Spatial inhomogeneity of the excess carrier density generated near the sample surface is considered. Strain effects on the band edges, on the band dispersions, and on the orbital compositions of the near gap states involved in radiative recombinations are fully taken into account. We obtain, as a function of the distance from the sample surface, the energy resolved absorption/gain spectra resulting from the contribution of the radiative direct and phonon-assisted band-to-band transitions and from the intra-band free carrier absorption. Photoluminescence spectra are calculated from the spatially dependent spontaneous radiative recombination rate, taking into account energy-dependent self-absorption effects. For suitable combinations of doping density, strain magnitude, pump power, and emitted photon polarization, we find gain values up to 5800 cm−1.
Note: Tesla based pulse generator for electrical breakdown study of liquid dielectrics
Authors: Veda Prakash G. , Kumar R. , Patel J. , Saurabh K. , Shyam A.
Published: December 2013

In the process of studying charge holding capability and delay time for breakdown in liquids under nanosecond (ns) time scales, a Tesla based pulse generator has been developed. Pulse generator is a combination of Tesla transformer, pulse forming line, a fast closing switch, and test chamber. Use of Tesla transformer over conventional Marx generators makes the pulse generator very compact, cost effective, and requires less maintenance. The system has been designed and developed to deliver maximum output voltage of 300 kV and rise time of the order of tens of nanoseconds. The paper deals with the system design parameters, breakdown test procedure, and various experimental results. To validate the pulse generator performance, experimental results have been compared with PSPICE simulation software and are in good agreement with simulation results.
Low-noise low-jitter 32-pixels CMOS single-photon avalanche diodes array for single-photon counting from 300 nm to 900 nm
Authors: Scarcella Carmelo , Tosi Alberto , Villa Federica , Tisa Simone , Zappa Franco
Published: December 2013

We developed a single-photon counting multichannel detection system, based on a monolithic linear array of 32 CMOS SPADs (Complementary Metal-Oxide-Semiconductor Single-Photon Avalanche Diodes). All channels achieve a timing resolution of 100 ps (full-width at half maximum) and a photon detection efficiency of 50% at 400 nm. Dark count rate is very low even at room temperature, being about 125 counts/s for 50 μm active area diameter SPADs. Detection performance and microelectronic compactness of this CMOS SPAD array make it the best candidate for ultra-compact time-resolved spectrometers with single-photon sensitivity from 300 nm to 900 nm.
Two-step laser ionization schemes for in-gas laser ionization and spectroscopy of radioactive isotopes
Authors: Kudryavtsev Yu. , Ferrer R. , Huyse M. , Van den Bergh P. , Van Duppen P. , Vermeeren L.
Published: December 2013

The in-gas laser ionization and spectroscopy technique has been developed at the Leuven isotope separator on-line facility for the production and in-source laser spectroscopy studies of short-lived radioactive isotopes. In this article, results from a study to identify efficient optical schemes for the two-step resonance laser ionization of 18 elements are presented.
High current H2+ and H3+ beam generation by pulsed 2.45 GHz electron cyclotron resonance ion source
Authors: Xu Yuan , Peng Shixiang , Ren Haitao , Zhao Jie , Chen Jia , Zhang Ailin , Zhang Tao , Guo Zhiyu , Chen Jia'er
Published: December 2013

The permanent magnet 2.45 GHz electron cyclotron resonance ion source at Peking University can produce more than 100 mA hydrogen ion beam working at pulsed mode. For the increasing requirements of cluster ions (H2+ and H3+) in linac and cyclotron, experimental study was carried out to further understand the hydrogen plasma processes in the ion source for the generation of cluster ions. The constituents of extracted beam have been analyzed varying with the pulsed duration from 0.3 ms to 2.0 ms (repetition frequency 100 Hz) at different operation pressure. The fraction of cluster ions dramatically increased when the pulsed duration was lower than 0.6 ms, and more than 20 mA pure H3+ ions with fraction 43.2% and 40 mA H2+ ions with fraction 47.7% were obtained when the operation parameters were adequate. The dependence of extracted ion fraction on microwave power was also measured at different pressure as the energy absorbed by plasma will greatly influence electron temperature and electron density then the plasma processes in the ion source. More details will be presented in this paper.
Nonexistence of global solution to Chern-Simons-Higgs system
Authors: Yuan Jianjun
Published: December 2013

In this paper, we show that for a class of Higgs potentials V, the 2+1-dimensional Chern-Simons-Higgs system with negative energy or zero energy together with \documentclass[12pt]{minimal}\begin{document}$(\frac{d}{dt}\int |\phi (t,x)|^2dx)(0)>0$\end{document}(ddt∫|ϕ(t,x)|2dx)(0)>0 blows up in finite time.
On the essential spectrum of certain non-commutative oscillators
Authors: Parmeggiani Alberto , Venni Alberto
Published: December 2013

We show here that the spectrum of the family of non-commutative harmonic oscillators \documentclass[12pt]{minimal}\begin{document}$Q_{(\alpha ,\beta )}^\mathrm{w}(x,D)$\end{document}Q(α,β)w(x,D) for \documentclass[12pt]{minimal}\begin{document}$\alpha ,\beta \in \mathbb {R}_+$\end{document}α,β∈R+ in the range αβ = 1 is [0, +∞) and is entirely essential spectrum. The previous existing results concern the case αβ > 1 (case in which \documentclass[12pt]{minimal}\begin{document}$Q_{(\alpha ,\beta )}^\mathrm{w}(x,D)$\end{document}Q(α,β)w(x,D) is globally elliptic with a discrete spectrum whose qualitative properties are being extensively studied), and ours therefore extend the picture to the range of parameters αβ ⩾ 1.
Phase transformations, heat evolution, and atomic diffusion during slow heating of Al-rich Al/Zr multilayered foils
Authors: Fisher Kaitlynn , Barron S. C. , Bonds M. A. , Knepper R. , Livi K. J. T. , Campbell G. H. , Browning N. D. , Weihs T. P.
Published: December 2013

We describe the energy and sequence of phase transformations in multilayered Al/Zr foils with atomic ratios of 3 Al:1 Zr during low temperature (<350 °C) heat treatments in a differential scanning calorimeter. The initial phase formed is an Al-rich amorphous phase that appears to grow by Zr diffusion through the amorphous phase. The subsequent nucleation and growth of tetragonal Al3Zr along the Al/amorphous layer interface is mediated by Al diffusion through the crystalline intermetallic phase. Diffusion coefficients associated with these processes are higher than expected from reports of diffusivities measured at higher temperatures. The inferred heat of formation of the tetragonal Al3Zr phase is 1240 ± 40 J/g (53 ± 2 kJ/mol atom). No anomalous variation in the energy or sequence of phase transformations is found with bilayer thickness for samples with bilayer thickness in the range of 17 nm to 90 nm despite anomalies in the bilayer dependence of self-propagating reaction velocities in the same foils.