bluuebunny/crossref_metadata_2025 huggingface dataset:
Utilizing discarded plastic bags as matrix material for composites reinforced with chicken feathers
Authors: Yang Yiqi , Reddy Narendra
Published: March 2013

High‐ density polyethylene (HDPE) in used plastic bags was reinforced with chicken feathers to develop composites in an effort to add value and reduce the amount of the plastics and feathers disposed in landfills. Feathers are biodegradable, derived from renewable resource, and are inexpensive and HDPE in plastic bags is mostly discarded in landfills. Utilizing feathers as reinforcement for HDPE composites will provide an opportunity to develop environmentally friendly composites. In this research, HDPE plastic bags were reinforced with chicken feathers and the flexural, tensile and acoustic properties were studied. It was found that incorporating feathers substantially improved the flexural properties and tensile modulus. At the optimum condition, the HDPE‐feather (50/50) composites had flexural strength of 13.9 MPa and stiffness of 0.45 N/mm compared to 9.8 MPa and 0.29 N/mm for 100% HDPE. The 50/50 HDPE‐feather composite had similar tensile strength but more than twice the tensile modulus of neat HDPE. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Physicochemical Properties and Photodynamic Activity of Novel Derivatives of Triarylmethane and Thiazine
Authors: Montes de Oca María N. , Vara Jimena , Milla Laura , Rivarola Viviana , Ortiz Cristina S.
Published: March 2013

Triarylmethane and thiazine dyes have attracted attention as anticancer and antimicrobial agents, due to their structural features and selective localizations. Although these dyes have been initially explored in the context of photodynamic therapy, some of these such as New Fuchsin and Azure B have still not been extensively investigated. For this reason, we evaluated the chemical stability, aggregation effect, and lipophilicity, as well as the photodynamic activity against LM‐2 murine mammary carcinoma cells of five new brominated dyes of triarylmethane and thiazine. These cationic compounds were obtained at high purities and unequivocally characterized by conventional techniques. The introduction of bromine atoms into the chromophoric system of New Fuchsin and Azure B dyes gave rise to a moderate bathochromic shift and increased the lipophilicity, thereby improving their photophysical and photochemical properties for biomedical applications. Moreover, the in vitro photodynamic activity demonstrated that, as the degree of bromination increased, the phototoxicity remained unchanged or decreased. The lower efficiency to inactivate cultured tumor cells may be attributed to the formation of the colorless carbinol pseudobase and aggregation effects for triarylmethane and thiazine dyes, respectively. A promising strategy to reverse the biological activity decrease observed might be the design of third‐generation photosensitizers.
Serotonin Hypothesis of Autism: Implications for Selective Serotonin Reuptake Inhibitor Use during Pregnancy
Authors: Harrington Rebecca A. , Lee Li‐Ching , Crum Rosa M. , Zimmerman Andrew W. , Hertz‐Picciotto Irva
Published: March 2013

Serotonin, a neurotransmitter found throughout the brain and body, has long been of interest in autism. Repeated findings of elevated platelet serotonin levels in approximately one third of children with autism has led some to believe that dysfunctional serotonin signaling may be a causal mechanism for the disorder. Because serotonin is critical to fetal brain development, concerns have arisen regarding prenatal exposure to substances that manipulate serotonin levels, such as selective serotonin reuptake inhibitors (SSRIs). This review examines evidence regarding the serotonin system and autism spectrum disorders (ASD), as well as what the literature has reported thus far on developmental effects of prenatal exposure to SSRIs. Possible mechanisms by which SSRIs could affect the fetus during pregnancy and clinical implications are also discussed. Though the majority of studies conducted in infants and children suggest prenatal exposure to SSRIs does not affect neurodevelopment, interpretation must be tempered given small sample sizes. The only published study that focused on prenatal SSRI exposure and ASD found an increased risk with exposure to SSRIs, especially during the first trimester. Obstacles that will be faced in future research are isolating medication effects from maternal depression and, given the infrequent occurrence of exposure and outcome, obtaining an adequate sample size. Whether serotonin is an etiologic factor in ASD, and what it points to as a marker for subgrouping, remains unclear. Understanding how the development of ASD might be affected by prenatal factors that influence serotonin levels, such as SSRIs, could identify modifiable targets for prevention. Autism Res 2013, 6: 149–168. © 2013 International Society for Autism Research, Wiley Periodicals, Inc.
Isolation and characterization of a novel oxidant‐ and surfactant‐stable extracellular alkaline protease from Exiguobacterium profundumBK‐P23
Authors: Anbu Periasamy , Hur Byung Ki , Gyun Lee Choul
Published: March 2013

The novel protease from Exiguobacterium profundum BK‐P23 was partially purified by ammonium sulfate precipitation and further purified Mono Q 5/50 and Superdex 200 10/300 column chromatography. The enzyme was purified 10.23‐fold with a yield of 14%. The molecular weight was estimated to be 52 kDa by SDS‐PAGE. The enzyme was most active at a pH of 8.0 and temperature of 40°C and the enzyme was stable between a pH of 7 and 10 and up to a temperature of 50°C. The enzyme activity was enhanced by CaCl2 but was slightly inhibited by CoCl2, MgSO4, and AgNO3. In addition, this enzyme was completely inhibited by phenylmethylsulfonyl fluoride, indicating that this enzyme was a serine protease. Furthermore, the alkaline protease was more stable in the presence of surfactants such as Triton X‐100, which was followed by Tween 80 and SDS. Moreover, the enzyme was highly stable in the presence of 1% oxidizing agent (H2O2). The enzyme also has significant stability (70%–80%) in a few organic solvents. Thus, the increased stability of the enzyme in the presence of oxidizing agent, surfactants, and organic solvents may find potential applications in the detergent industry and peptide synthesis in nonaqueous media.
Exploring the potential of megaprimer PCR in conjunction with orthogonal array design for mutagenesis library construction
Authors: Tang Lixia , Zheng Kai , Liu Yu , Zheng Huayu , Wang Hu , Song Chunlei , Zhou Hong
Published: March 2013

Although megaprimer PCR mutagenesis has been used routinely in protein directed evolution, users sometimes encounter technical hurdles, particularly inefficiency during amplification when large fragments are used or the template is difficult to be amplified. Instead of methodology development, here we simply overcome the limitation by optimizing megaprimer PCR conditions via orthogonal array design of the four PCR components in three levels of each: template, primer, Mg2+, and dNTPs. For this, only nine PCRs need to be performed. The strategy (termed as OptiMega) was not only successfully applied for the construction of one multiple‐site saturation mutagenesis library of halohydrin dehalogenase HheC, which failed to be constructed previously using the standard QuikChange™ protocol, but also expanded the construction of two high‐quality random mutagenesis libraries of HheA and HheC. Most importantly, OptiMega offers a quick and simple way of constructing random mutagenesis libraries by eliminating the ligation step. Our results demonstrated that the OptiMega strategy could greatly strengthen the potential of megaprimer PCR mutagenesis for library construction.
Covalent immobilization of xylanase produced from Bacillus pumilusSV‐85S on electrospun polymethyl methacrylate nanofiber membrane
Authors: Kumar Pankaj , Gupta Ashish , Dhakate Sanjay R. , Mathur Rakesh B. , Nagar Sushil , Gupta Vijay K.
Published: March 2013

Polymethyl methacrylate (PMMA) nanofiber membrane (NFM) was synthesized by an electrospinning technique. These membranes were utilized as a support for immobilization of xylanase enzyme to study its pH stability, thermal stability, and reusability. The morphology of aligned NFM was studied by optical microscopy and scanning electron microscopy. The PMMA NFM was functionalized with phenylenediamine and activated with glutaraldehyde to yield an aldehyde group on its surface for covalent immobilization of xylanase. The Fourier transform infrared analysis of the covalently immobilized xylanase confirmed that the enzyme was immobilized on PMMA NFM via amide linkages. The immobilization efficiency of covalently bound xylanase was found experimentally to be 90%. A forward shift in pH optima from 6.0–7.0 (soluble enzyme) to 7.0–9.0 (immobilized enzyme) was observed after xylanase immobilization. The pH and temperature stability of xylanase were enhanced upon its covalent immobilization. The immobilized enzyme was active on repeated use and retained ∼80% of its initial activity after 11 reaction cycles. The improved thermal and operational stability of the covalently immobilized enzyme on PMMA NFM might be advantageous for industrial applications.
A Review of Developmental and Reproductive Toxicity of CS2and H2S Generated by the Pesticide Sodium Tetrathiocarbonate
Authors: Silva Marilyn
Published: March 2013

BACKGROUND

Sodium tetrathiocarbonate (STTC) is an example of a pesticide that when prepared for use in aqueous solution releases two toxic products carbon disulfide (CS2) (active ingredient) and hydrogen sulfide (H2S) in ambient air in equimolar concentrations resulting in potential exposure to workers and bystanders. CS2and H2S are pollutants that are generated from several pesticides as well as in industrial settings.

METHODS

Registrant submitted reports and open literature studies for STTC, CS2and H2S were reviewed. Previous reports suggest that CS2was a concern as a developmental and reproductive toxicant. H2S was also examined since it is a neurotoxicant and potentially harmful to developing fetuses.

RESULTS

STTC did not induce developmental or reproductive effects in animal studies. CS2was a developmental neurobehavioral toxin in rat pups (inhalation no observed effect level [NOEL] = 0.01ppm). Reproductive effects occurred in male and female factory workers after CS2exposure (NOEL = 1ppm). H2S had developmental effects in rats at doses at or above those observed for nasal pathology (NOEL = 10ppm) but was not a reproductive or developmental toxin in humans.

CONCLUSIONS

The database for CS2indicates a strong potential for developmental neurotoxicity in animals at low doses but it is lacking in acceptable, well‐performed studies. There is also a lack of studies performed with CS2and H2S as a mixture.
Application of capillary electrophoresis coupling with electrochemiluminescence detection to estimate activity of leucine aminopeptidas
Authors: Su Ming , Wei Min , Zhou Zhixin , Liu Songqin
Published: March 2013

A new method to estimate the leucine aminopeptidase (LAP, EC 3.4.11.1) activity using capillary electrophoresis coupled with electrochemiluminescence (ECL) is described. The liberated proline produced by LAP catalyzing the hydrolysis reaction of leucin–proline was used as an ECL coreagent to enhance Ru(bpy)32+ECL signals efficiently. The detection limit for proline was 2.88 × 10−6 m(signal‐to‐noise ratio 3), which was equal to 9.60 × 10−8units of LAP being used to catalyze leucin–proline for 1 min. The Michaelis constantKm(2.07 × 10−2 mol/L) and the maximum reaction velocityVmax(1.06 × 10−5 mol/L/min) of LAP for leucin–proline are reported. The reaction conditions including the concentration of metal ions, incubation temperature and pH were optimized. This method was successfully applied to detect LAP activity in plasma and the results were in good agreement with that obtained by the clinical method. Copyright © 2013 John Wiley & Sons, Ltd.
A Computational Evaluation of the Evidence for the Synthesis of 1,3‐Dimethylcyclobutadiene in the Solid State and Aqueous Solution
Authors: Rzepa Henry S.
Published: March 2013

Density functional calculations of 1H NMR spectra and reaction barriers at the ωB97XD/6‐311G(d,p)/continuum water level do not support the claimed identification of encarcerated 1,3‐dimethylcyclobutadiene in either the solid state or aqueous solution, as reported by Barboiu et al (Chem. Eur. 2011, 17, 10021). Instead, previous suggestions that the species identified in the solid state is in fact 2‐oxabicyclo[2.2.0]hex‐5‐en‐3‐one (the Dewar lactone Me22) are reaffirmed. Analysis of the ground‐state electronic structure of this species indicates an unusual π‐anomeric effect is promoting a Dunitz‐like chemical reaction pathway leading to the eventual elimination of carbon dioxide and formation of 1,3‐dimethylcyclobutadiene.
Synthesis, Structure, and Electronic Properties of Extended π‐Conjugated Group 6 Fischer Alkoxy–Bis(carbene) Complexes
Authors: Chu Gong M. , Fernández Israel , Sierra Miguel A.
Published: March 2013

The synthesis, structure and electronic properties of novel Group 6 Fischer alkoxy–bis(carbene) complexes are reported. The UV/Vis spectra of these species display two main absorptions at approximately 350 and 550 nm attributable to a ligand‐field (LF) and metal‐to‐ligand charge‐transfer (MLCT) transitions, respectively. The planarity of the system and the cooperative effect of both pentacarbonyl metal moieties greatly enhance the conjugation between the group at the end of the spacer and the metal carbene fragment provoking dramatic changes in the LF and MLCT absorptions. This is in contrast to related push–pull Fischer monocarbenes, where the position of the MLCT band remains mostly unaltered regardless the substituent attached to the donor fragment. In addition, the MLCT maxima can be tuned with subtle modifications of the electronic nature of the central aryl fragment in the novel A–π‐D–π‐A (A=acceptor, D=donor) systems. DFT and time‐dependent (TD) DFT quantum chemical calculations at the B3LYP/def2‐SVP level have also been performed to determine the minimum‐energy molecular structure of this family of compounds and to analyse the nature of the vertical one‐electron excitations associated to the observed UV/Vis absorptions as well as to rationalise their electrochemical behaviour. The ability of tuning up the electronic properties of the compounds studied herein may be of future use in material chemistry.
Macro‐ and Microkinetic Simulation of Diesel Oxidation Catalyst: Effect of Aging, Noble Metal Loading and Platinum Oxidation
Authors: Hauff Karin , Boll Willi , Tischer Steffen , Chan Denise , Tuttlies Ute , Eigenberger Gerhart , Deutschmann Olaf , Nieken Ulrich
Published: March 2013

In automotive exhaust aftertreatment simulation, both macro‐ and microkinetic models are commonly used. In this contribution both models are applied for the simulation of diesel oxidation catalysts (Pt/γ‐Al2O3) with different catalyst loading and degree of thermal aging. The study proves that the structure insensitive kinetics of the considered catalysts can be described with the same rate equations only by scaling the rate constants of the different reaction steps with the catalytically active Pt surface, which is accessible by CO adsorption or light‐off measurements. In addition, NO oxidation is strongly influenced by a reversible, slow transformation of Pt into Pt‐oxide.
Influence of Body Mass Index on Recurrence and Quality of Life in Atrial Fibrillation Patients After Catheter Ablation: A Meta‐Analysis and Systematic Review
Authors: Zhuang Jianhui , Lu Yuyan , Tang Kai , Peng Wenhui , Xu Yawei
Published: March 2013

Background

Accumulating evidence has demonstrated that overweight and obesity, expressed as high body mass index (BMI), are associated with the development of atrial fibrillation (AF) and quality of life (QoL) in AF patients. However, the role of high BMI as a risk factor for prognosis and QoL in AF patients undergoing ablation remains controversial.

Hypothesis

We hypothesized that elevated BMI was correlated with AF recurrence and QoL after an ablative procedure.

Methods

We performed a comprehensive search of PubMed, EMBASE, and the Cochrane Library. Studies were included if they investigated the association of BMI with AF recurrence and QoL after ablation.

Results

Of the 151 articles identified, 12 studies that enrolled 3286 individuals met the inclusion criteria. Overall, compared with normal‐BMI patients, AF recurrence occured more frequently in high‐BMI patients after ablation (odds ratio: 1.32, 95% confidence interval: 1.17‐1.5, P < 0.001). However, the pooled esimate of odds ratio adjusted for multiple confounders did not reach significance. The summary weighted mean difference of BMI between patients with and without recurrence was 0.43 (95% confidence interval: 0.05‐0.81, P = 0.027). In addition, QoL scores were significantly lower in high‐BMI than in normal‐BMI patients before the ablative procedure, whereas the gap of QoL between normal‐BMI and high‐BMI groups was decreased at follow‐up.

Conclusions

Results of this meta‐analysis suggest 2 points, namely that the tight association between overweight/obesity and AF recurrence after ablation may be partly due to other concomitant conditions, and that impaired QoL in high‐BMI groups is significantly improved after ablation.
Quantitation of the Mitral Tetrahedron in Patients With Ischemic Heart Disease Using Real‐Time Three‐Dimensional Echocardiography to Evaluate the Geometric Determinants of Ischemic Mitral Regurgitation
Authors: Hsuan Chin‐Feng , Yu Hsi‐Yu , Tseng Wei‐Kung , Lin Lung‐Chun , Hsu Kwan‐Lih , Wu Chau‐Chung
Published: March 2013

Background

Ischemic mitral regurgitation (IMR) is common in ischemic heart disease and results in poor prognosis. However, the exact mechanism of IMR has not been fully elucidated.

Hypothesis

Quantitation of the mitral tetrahedron using three‐dimentianl (3D) echocardiography is capable of evaluating the geometric determinants and mechanisms of IMR.

Methods

Forty patients with a history of ST‐elevation myocardial infarction at least 6 months earlier were studied. Parameters of mitral deformation and global left ventricular (LV) function and shape were evaluated by 2‐dimensional echocardiography. The effective regurgitant orifice (ERO) of IMR was obtained by the quantitative continuous‐wave Doppler technique. Three‐dimensional (3D) echocardiography was applied to assess the mitral tetrahedron.

Results

Mitral valvular tenting area (P < 0.001), mitral annular area (P = 0.032), dilation of the LV in diastole, impairment of the LV ejection fraction, and volume of the spherically shaped LV in systole were greater in patients with an ERO ≥20 mm2 than in those with an ERO <20 mm2. In the mitral tetrahedron, only the interpapillary muscle roots distance showed a significant difference (P = 0.004). Multivariate analysis with the logistic regression model showed the systolic mitral tenting area (odds ratio [OR]: 280.49, 95% confidence interval [CI]: 4.59‐1.72 × 104, P = 0.007) and interpapillary muscle distance (OR: 1.50, 95% CI: 1.03‐2.19, P = 0.036) to be independent factors in predicting significant IMR (ERO ≥20 mm2).

Conclusions

3D echocardiography can be effectively applied in measuring the mitral tetrahedron and evaluating the mechanism of IMR. Mitral valvular tenting and interpapillary muscle distance are 2 independent factors of significant IMR.
Controversies in antiepidermal growth factor receptor therapy in metastatic colorectal cancer
Authors: Woo Janghee , Palmisiano Neil , Tester William , Leighton John C.
Published: March 2013

The randomized first‐line trials, including the CRYSTAL trial, the OPUS trial, and the PRIME trial, have demonstrated the significant efficacy of cetuximab or panitumumab in patients with v‐Ki‐ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) wild‐type tumors. The addition of an antiepidermal growth factor receptor (anti‐EGFR)‐directed monoclonal antibody to chemotherapy for these patients significantly improved progression‐free survival, response rates, and R0 resection rates to a greater extent than overall survival compared with patients who received chemotherapy alone. However, 2 recent randomized phase 3 trials, the MRC COIN trial and the Nordic VII trial, reported an unexpected lack of benefit from the addition of cetuximab to chemotherapy in the first‐line setting. In addition, recent retrospective analyses performed on a pooled data set from major clinical trials added more complexity, reporting an unexpected association of KRAS G13D mutation with a better clinical outcome compared with patients who had other KRAS mutations in the first‐line and salvage settings, whereas the other independent analysis failed to demonstrate a benefit from panitumumab in patients with the same KRAS G13D mutation. The anti‐EGFR monoclonal antibody‐associated skin toxicity and the controversial strategies of management also are discussed. In this review, the authors analyze the previous randomized clinical trials and more critically re‐evaluate recent trials and subgroup analyses to derive 3 factors that need to be taken into consideration regarding the addition of EGFR‐directed monoclonal antibodies to chemotherapy: the preclinical data on mechanisms of action between chemotherapy and anti‐EGFR antibodies along with mechanisms of resistance to anti‐EGFR antibodies, the role of cross‐over events in overall survival data, and the significant dose reductions of chemotherapeutic agents when combined with anti‐EGFR agents. Cancer 2013;119:1941–1950. © 2013 American Cancer Society.
Estrogen receptor‐positive/human epidermal growth factor receptor 2‐negative breast tumors
Authors: Groheux David , Hatt Mathieu , Hindié Elif , Giacchetti Sylvie , de Cremoux Patricia , Lehmann‐Che Jacqueline , Martineau Antoine , Marty Michel , Cuvier Caroline , Cheze‐Le Rest Catherine , de Roquancourt Anne , Visvikis Dimitris , Espié Marc
Published: March 2013

BACKGROUND

The objective of this prospective study was to evaluate the ability of 18F‐fluorodeoxyglucose (18F‐FDG) positron emission tomography/computed tomography (PET/CT) to predict chemosensitivity in patients with estrogen receptor (ER)‐positive/human epidermal growth factor receptor 2 (HER2)‐negative breast cancer.

METHODS

Sixty‐four consecutive patients underwent 18F‐FDG PET/CT scanning at baseline and after the second course of neoadjuvant chemotherapy (NAC). The evolution (Δ) between the 2 scans of image parameters (maximum standardized uptake value [SUVmax], SUVmean, metabolic tumor volume, and total lesion glycolysis [TLG]) was measured. Correlations between early changes in PET‐derived parameters and pathologic response observed in surgical specimens after the completion of 8 courses of NAC were estimated with Mann‐Whitney U tests. Response prediction on the basis of clinical data, histologic type, or molecular markers also was assessed (Fisher exact test). Receiver operating characteristic (ROC) analysis was used to compare the area under the curve (AUC) of each parameter.

RESULTS

The best prediction of chemosensitivity was obtained with ΔTLG (−49% ± 31% in nonresponders vs −73% ± 25% in responders; P < .0001). Among the biologic parameters, only negative progesterone receptor status (57% responders vs 31% nonresponders; P = .04) and luminal B subtype (63% responders vs 22% nonresponders; P = .02) were predictive of a pathologic response. ROC analysis resulted in an AUC of 0.81, 0.73, 0.71, and 0.63 for ΔTLG, ΔSUVmax, luminal subtype, and progesterone receptor status, respectively.

CONCLUSIONS

When patients responded to NAC, the majority of ER‐positive/HER2 negative tumors exhibited partial tumor shrinkage; and the PET parameters that combined volume and activity measurements, such as TLG, offered better accuracy for early prediction than the SUVmax. Negative progesterone receptor status and luminal B subtype had weaker predictive power than PET‐derived parameters. Cancer 2013;119:1960–1968. © 2013 American Cancer Society.
Electrochemical Oxygen Reduction Behavior of Selectively Deposited Platinum Atoms on Gold Nanoparticles
Authors: Sarkar A. , Kerr J. B. , Cairns E. J.
Published: March 2013

Carbon‐supported Pt@Au “core‐shell” nanoparticles with varying surface concentration of platinum atoms have been synthesized using a novel redox‐mediated synthesis approach. The synthesis technique allows for a selective deposition of platinum atoms on the surface of prefabricated gold nanoparticles. Energy dispersive spectroscopic analyses in a scanning electron microscope reveal that the platinum to gold atomic ratios are close to the nominal values, validating the synthesis scheme. X‐ray diffraction data indicate an un‐alloyed structure. The platinum to gold surface atomic ratio determined from cyclic voltammetry and copper under‐potential deposition experiments reveal good agreement with the calculated values at low platinum concentration. However, there is an increase in non‐uniformity in the deposition process upon increasing the platinum concentration. Koutecky–Levich analysis of the samples indicates a transition of the total number of electrons transferred (n) in the electrochemical oxygen reduction reaction from two to four electrons upon increasing the surface concentration of platinum atoms. Furthermore, the data indicate that isolated platinum atoms can reduce molecular oxygen but via a two‐electron route. Moreover, successful four‐electron reduction of molecular oxygen requires clusters of platinum atoms.
Two‐Pulse Control of Large‐Amplitude Vibrations in H2+
Authors: Chang Bo Y. , Shin Seokmin , Palacios Alicia , Martín Fernando , Sola Ignacio R.
Published: March 2013

A laser‐adiabatic manipulation of the bond (LAMB) scheme using moderately intense fields is proposed to induce and control large‐amplitude oscillations in nuclear wave packets. The present scheme involves an ultrashort UV pump pulse to initially create a wave packet in an excited electronic state of the hydrogen molecular ion and a low‐frequency control pulse, which is switched on after a given time, leading to controllable vibrational trapping. The choice of H2+ as the target exploits the larger dipole values that molecular ions present as the internuclear distance increases. The amplitude and oscillation period of the wave packet is tuned by the field parameters of the control pulse, and more importantly, significant dissociation and ionization losses are prevented by keeping the laser intensities below hundreds of Terawatts. Our numerical simulations, based on the solution of the time‐dependent Schrödinger equation, show that this control of the bond length is achieved in a wide range of moderate intensities and for relatively long pulse durations, from tens to hundreds of femtoseconds.
A Pedagogical Perspective on Ambipolar FETs
Authors: Kang Moon Sung , Frisbie C. Daniel
Published: March 2013

The operation of an ambipolar field‐effect transistor (FET) is described using a simple diagram depicting the gate voltage and channel potential profile relative to the injection threshold voltage of charge carriers. From this diagram, the transition between transistor‐operation regimes and the resulting current–voltage relations can be easily understood. Also, a practical guidance for the operation of an ambipolar FET is provided. In particular, conditions to achieve the true ambipolar regime, which is of particular interest for light‐emitting transistor operation, and a correct method to extract electron and hole mobilities from a given current–voltage curve are presented.
TripleFRET measurements in flow cytometry
Authors: Fábián Ákos , Horváth Gábor , Vámosi György , Vereb György , Szöllősi János
Published: March 2013

A frequently used method for viewing protein interactions and conformation, Förster (fluorescence) resonance energy transfer (FRET), has traditionally been restricted to two fluorophores. Lately, several methods have been introduced to expand FRET methods to three species. We present a method that allows the determination of FRET efficiency in three‐dye systems on a flow cytometer. TripleFRET accurately reproduces energy transfer efficiency values measured in two‐dye systems, and it can indicate the presence of trimeric complexes, which is not possible with conventional FRET methods. We also discuss the interpretation of energy transfer values obtained with tripleFRET in relation to spatial distribution of labeled molecules, specifically addressing the limitations of using total energy transfer to determine molecular distance. © 2013 International Society for Advancement of Cytometry
Response to multi‐generational selection under elevated [CO2] in two temperature regimes suggests enhanced carbon assimilation and increased reproductive output in Brassica napus L.
Authors: Frenck Georg , van der Linden Leon , Mikkelsen Teis Nørgaard , Brix Hans , Jørgensen Rikke Bagger
Published: March 2013

Functional plant traits are likely to adapt under the sustained pressure imposed by environmental changes through natural selection. Employing Brassica napus as a model, a multi‐generational study was performed to investigate the potential trajectories of selection at elevated [CO2] in two different temperature regimes. To reveal phenotypic divergence at the manipulated [CO2] and temperature conditions, a full‐factorial natural selection regime was established in a phytotron environment over the range of four generations. It is demonstrated that a directional response to selection at elevated [CO2] led to higher quantities of reproductive output over the range of investigated generations independent of the applied temperature regime. The increase in seed yield caused an increase in aboveground biomass. This suggests quantitative changes in the functions of carbon sequestration of plants subjected to increased levels of CO2 over the generational range investigated. The results of this study suggest that phenotypic divergence of plants selected under elevated atmospheric CO2 concentration may drive the future functions of plant productivity to be different from projections that do not incorporate selection responses of plants. This study accentuates the importance of phenotypic responses across multiple generations in relation to our understanding of biogeochemical dynamics of future ecosystems. Furthermore, the positive selection response of reproductive output under increased [CO2] may ameliorate depressions in plant reproductive fitness caused by higher temperatures in situations where both factors co‐occur.
Cellular‐FLIP, Raji isoform (c‐FLIPR) modulates cell death induction upon T‐cell activation and infection
Authors: Telieps Tanja , Ewald Frida , Gereke Marcus , Annemann Michaela , Rauter Yvonne , Schuster Marc , Ueffing Nana , von Smolinski Dorthe , Gruber Achim D. , Bruder Dunja , Schmitz Ingo
Published: March 2013

Dysregulation of apoptosis caused by an imbalance of pro‐ and anti‐apoptotic protein expression can lead to cancer, neurodegenerative, and autoimmune diseases. Cellular‐FLIP (c‐FLIP) proteins inhibit apoptosis directly at the death‐inducing signaling complex of death receptors, such as CD95, and have been linked to apoptosis regulation during immune responses. While the isoforms c‐FLIPL and c‐FLIPS are well characterized, the function of c‐FLIPR remains poorly understood. Here, we demonstrate the induction of endogenous murine c‐FLIPR in activated lymphocytes for the first time. To analyze c‐FLIPR function in vivo, we generated transgenic mice expressing murine c‐FLIPR specifically in hematopoietic cells. As expected, lymphocytes from c‐FLIPR transgenic mice were protected against CD95‐induced apoptosis in vitro. In the steady state, transgenic mice had normal cell numbers and unaltered frequencies of B cells and T‐cell subsets in lymphoid organs. However, when challenged with Listeria monocytogenes, c‐FLIPR transgenic mice showed less liver necrosis and better bacterial clearance compared with infected wild‐type mice. We conclude that c‐FLIPR expression in hematopoietic cells supports an efficient immune response against bacterial infections.
The capacity of Th2 lymphocytes to deliver B‐cell help requires expression of the transcription factor STAT3
Authors: Mari Nathalie , Hercor Mélanie , Denanglaire Sébastien , Leo Oberdan , Andris Fabienne
Published: March 2013

CD4+ T‐cell help for B cells is crucial for effective Ab responses. Although follicular T helper (Tfh) cells have emerged as the main providers of T‐cell help to B lymphocytes during the germinal center reaction, much less is known about the helper capacities of other effector CD4+ T cells. The purpose of the present study was to evaluate the acquisition of B‐cell help capacity of canonically derived T helper 2 (Th2) cells, a Th‐cell subset originally considered responsible for B‐cell help in vivo. We demonstrate herein that developing Th2 cells in mice co‐express activated forms of signal transducer and activator of transcription 6 (STAT6) and STAT3 and that STAT3 expression was required for the capacity of Th2 cells to provide B‐cell help. Thus, Th2 lymphocytes share a common, STAT3‐mediated activation program for the acquisition of optimal B‐cell help capacity with Tfh cells. Moreover, the expression of STAT3 in Th2 cells enhanced the IgG1‐to‐IgE class switch ratio in vivo, a finding with important implications for understanding the molecular basis of allergic diseases.
IL‐22 modulates IL‐17A production and controls inflammation and tissue damage in experimental dengue infection
Authors: Guabiraba Rodrigo , Besnard Anne‐Gaëlle , Marques Rafael E. , Maillet Isabelle , Fagundes Caio T. , Conceição Thais M. , Rust Naiara M. , Charreau Sandrine , Paris Isabelle , Lecron Jean‐Claude , Renauld Jean‐Christophe , Quesniaux Valérie , Da Poian Andrea T. , Arruda Luciana B. , Souza Danielle G. , Ryffel Bernhard , Teixeira Mauro M.
Published: March 2013

Dengue virus (DENV), a mosquito‐borne flavivirus, is a public health problem in many tropical countries. IL‐22 and IL‐17A are key cytokines in several infectious and inflammatory diseases. We have assessed the contribution of IL‐22 and IL‐17A in the pathogenesis of experimental dengue infection using a mouse‐adapted DENV serotype 2 strain (P23085) that causes a disease that resembles severe dengue in humans. We show that IL‐22 and IL‐17A are produced upon DENV‐2 infection in immune‐competent mice. Infected IL‐22−/− mice had increased lethality, neutrophil accumulation and pro‐inflammatory cytokines in tissues, notably IL‐17A. Viral load was increased in spleen and liver of infected IL‐22−/− mice. There was also more severe liver injury, as seen by increased transaminases levels and tissue histopathology. γδ T cells and NK cells are sources of IL‐17A and IL‐22, respectively, in liver and spleen. We also show that DENV‐infected HepG2 cells treated with rhIL‐22 had reduced cell death and decreased IL‐6 production. IL‐17RA−/− mice were protected upon infection and IL‐17A‐neutralizing‐Ab‐treatment partially reversed the phenotype observed in IL‐22−/−‐infected mice. We suggest that disrupting the balance between IL‐22 and IL‐17A levels may represent an important strategy to reduce inflammation and tissue injury associated with severe dengue infection.
Wettability Control on ZnO Nanowires Driven by Seed Layer Properties
Authors: Laurenti Marco , Cauda Valentina , Gazia Rossana , Fontana Marco , Rivera Vivian Farías , Bianco Stefano , Canavese Giancarlo
Published: March 2013

This study proposes a way to control the wettability of zinc oxide nanowires (NWs) by properly selecting the kind of seed layer used to promote the growth of the wires. ZnO seed layers were synthesized on silicon and conductive substrates by a physical vapor deposition approach and a wet‐chemical route, namely, the radio frequency magnetron sputtering and the spin‐coating techniques, respectively. ZnO NWs were grown by a hydrothermal method on each kind of seed layer and the results were compared. The morphologies and crystallographic orientations of the seed layers and the resulting NWs were investigated with the aim of correlating the characteristics of the underlying seed layer to those of the resulting NWs. Additional insights were obtained by performing optical contact angle (OCA) measurements on ZnO seed layers to study their wettability behavior immediately after the synthesis processes and two weeks later. Hydrophilic behavior was observed in both sputtered and spin‐coated fresh seed layers. After two weeks of aging, a change in the wettability and a net transition from hydrophilic to hydrophobic behavior was observed in sputtered seed layers, whereas in the spin‐coated films this transition was not so pronounced and was found to be dependent on the precursor concentration. OCA measurements carried out on ZnO NWs showed that the wettability of the NWs is strictly related to the nature of the underlying seed layers and does not depend on the aging time, in contrast to the behavior of the seed layers. Depending on the deposition method, we therefore obtained either highly hydrophilic or superhydrophobic nanowires, which demonstrates the possibility to strongly control the final wetting behavior of these nanostructures for the desired application, such as self‐cleaning surfaces, antireflection coatings, or substrates to anchor biofunctional agents.
Enzymatic production of modified 2‐dodecyl‐sophorosides (biosurfactants) and their characterization
Authors: Recke Verena Kerstin , Gerlitzki Melanie , Hausmann Rudolf , Syldatk Christoph , Wray Victor , Tokuda Harukuni , Suzuki Nobutaka , Lang Siegmund
Published: March 2013

Alkyl sophorosides, a special type of sophorolipids, can be produced using Candida bombicola cultures with glucose as main carbon source and 2‐dodecanol as co‐substrate. The dominating component, 2‐dodecyl‐sophoroside SL‐E2‐12, was purified via medium pressure liquid chromatography (MPLC) and used as substrate for further enzymatic modifications. Using β‐glucuronidase in aqueous media the first modification gave a glycosidic cleavage of the acetyl glucose unit leading to 2‐dodecyl‐glucoside GL‐A2‐12. In a subsequent lipase‐catalyzed acylation with sebacic acid in toluene this compound was functionalized regioselectively at the primary C‐6′ position of glucose. Similar lipase‐catalyzed reactions in toluene, but now using SL‐E2‐12 as acyl acceptor and unusual hydroxyl fatty acids – 3‐hydroxy decanoic acid and 17‐hydroxy stearic acid – as acyl donors, resulted in mono‐ and diacylations of primary hydroxyl positions of the sophorose unit (C‐6′ and C‐6′′) as shown by NMR and MS studies. In physicochemical characterization experiments the new glycoconjugates lowered the surface tension of water from 72 to 27–32 mN/m. Moreover it was observed that the new products inhibit the growth of particular Gram‐positive bacteria. Additionally they indicate potential for anti‐tumor promoting activity.

Practical applications: According to literature data 2‐alkyl‐sophorosides can be produced using Candida bombicola cultures with yields of more than 20 g/L. Based on this starting material, 2‐dodecyl‐sophoroside, several regioselective enzymatic modifications were performed. Initially, β‐glucuronidase catalysis in aqueous buffer solution gave 2‐dodecyl‐glucoside which was then successfully acylated at the C‐6 position of glucose by lipase catalysis using a common dicarboxylic acid, sebacic acid. The resulting free carboxylic function of the acidic derivative opens up the possibility of achieving additional chemo‐enzymatic reactions at this position for conversion, for instance, into polyesters. In addition lipase catalysis in organic solvents of 2‐dodecyl‐sophoroside allows acylation with unusual hydroxyl fatty acids of microbial origin. Physicochemical studies showed that these new glycoconjugates may be of interest for the cosmetic industry due to moisture conservation of the skin. For practical applications the conditions of the above biocatalytic reactions have been improved and scaled up.
Tropos, Nevertheless Conformationally Stable Biphenyl Derivatives
Authors: Haberhauer Gebhard , Tepper Christina , Wölper Christoph , Bläser Dieter
Published: March 2013

Biphenyl derivatives with small substituents in the ortho and ortho′ positions are called tropos. Due to the low rotation barrier around the C–C bond connecting the two phenyl units, the isolation of only one conformer is not possible; thus they are conformationally unstable. Using DFT calculations, we were able to show that using a suitable peptidic bridging unit, biphenyl systems can become conformationally stable. This stabilization should be independent of the type of substituent in the ortho and ortho′ positions. Some of the proposed biphenyl derivatives were successfully synthesized and studied in solution and solid state. The recorded VT‐NMR, 2D‐NMR and CD spectra show that all biphenyl derivatives exhibit the P conformation. The preference for the P conformation is confirmed by the structure of a biphenyl derivative in solid state.
The Palos Verdes anticlinorium along the Los Angeles, California coast: Implications for underlying thrust faulting
Authors: Sorlien Christopher C. , Seeber Leonardo , Broderick Kris G. , Luyendyk Bruce P. , Fisher Michael A. , Sliter Ray W. , Normark William R.
Published: March 2013

The Palos Verdes anticlinorium (PVA) is a 70 km‐wide, NW‐trending Pliocene‐Quaternary transpressional high that separates the onshore Los Angeles basin from the offshore San Pedro basin. The PVA southwest limb underlies a 70 km‐long SW facing seafloor escarpment. This escarpment is separated into two segments by a 6 km right step. It overlies two levels of NE dipping low‐angle thrust faults. These faults project beneath Los Angeles toward known SW verging blind thrust faults and may be the same regional faults. These conclusions are based on a detailed geometric representation constructed from a regional analysis of 5000 km of multichannel seismic reflection profiles, logs, and paleontology from 19 wells, published seafloor geology, and multibeam bathymetric data. Patterns of sedimentation and erosion indicate that folding of PVA initiated during Pliocene time and propagated southward, with folding of part of the southern PVA occurring during the Quaternary. Structural relief continues to grow with regional long‐term rock uplift of the PVA crest and ongoing subsidence in the adjacent basins. The low‐angle NE‐dipping faults beneath the PVA must be late Quaternary active in order to maintain hanging wall rock uplift above subsiding footwalls. Structural geometry requires that the underlying faults have slipped at 1.1–1.6 mm/yr over Quaternary time.
Computerised cognitive behavioural therapy for depression and anxiety with older people: a pilot study to examine patient acceptability and treatment outcome
Authors: McMurchie William , Macleod Fiona , Power Kevin , Laidlaw Ken , Prentice Neil
Published: March 2013

Objective

The study objective was to determine the acceptability and treatment outcome of using Beating the Blues (BTB) with older people (65+ years). Specific aims included identifying the treatment uptake and drop‐out rate, and describing the role of basic demographics in therapy uptake.

Method

Fifty‐eight participants, experiencing symptoms of depression, were given a free choice of receiving treatment as usual (TAU) plus BTB (TAU + BTB) or TAU alone. All participants completed demographic questionnaires and a range of outcome measures at baseline, 2 months after baseline (end of treatment) and 3 months after baseline (follow‐up).

Results

Thirty‐three participants (56.9%) opted to receive BTB and reported having more experience and confidence using a computer than those who declined BTB. Twenty‐four participants (72.7%) went on to complete all eight BTB sessions. Statistical analysis found significant differences between the two treatment groups, with the TAU + BTB group showing greater improvements in their symptoms of depression and anxiety than the TAU group by the end of treatment and at follow‐up. Furthermore, the TAU + BTB group had a significantly higher percentage of participants who met criteria for clinically significant improvement in their symptoms of depression by the end of treatment and at follow‐up.

Conclusion

Although further research is required, including a randomised controlled trial, the results of this initial pilot study provide evidence that BTB may offer an acceptable and effective treatment option for older people. Copyright © 2013 John Wiley & Sons, Ltd.
The dependence of peak electron density in the ionosphere of Mars on solar irradiance
Authors: Girazian Z. , Withers P.
Published: March 2013

Previous studies of the Mars ionosphere have concluded that increased solar flux leads to increased peak electron densities. Many have described this relationship as Nm ∝ Fk, where Nmis the peak electron density, F, the ionizing flux, is represented by either F10.7 or E10.7, and k is an exponent. The derived exponents have varied greatly, but have a mean value of k ≃ 0.35. Here, we explore this relationship using solar spectra measurements from the TIMED‐SEE instrument and Mars Global Surveyor radio occultation data. Our derived exponents, k ≃ 0.50, are larger than those found by previous studies that used F10.7or E10.7and are close to the theoretical prediction of simplistic Chapman theory.
Isomap nonlinear dimensionality reduction and bimodality of Asian monsoon convection
Authors: Hannachi A. , Turner A.G.
Published: March 2013

It is known that the empirical orthogonal function method is unable to detect possible nonlinear structure in climate data. Here, isometric feature mapping (Isomap), as a tool for nonlinear dimensionality reduction, is applied to 1958–2001 ERA‐40 sea‐level pressure anomalies to study nonlinearity of the Asian summer monsoon intraseasonal variability. Using the leading two Isomap time series, the probability density function is shown to be bimodal. A two‐dimensional bivariate Gaussian mixture model is then applied to identify the monsoon phases, the obtained regimes representing enhanced and suppressed phases, respectively. The relationship with the large‐scale seasonal mean monsoon indicates that the frequency of monsoon regime occurrence is significantly perturbed in agreement with conceptual ideas, with preference for enhanced convection on intraseasonal time scales during large‐scale strong monsoons. Trend analysis suggests a shift in concentration of monsoon convection, with less emphasis on South Asia and more on the East China Sea.
Climate impacts of a large‐scale biofuels expansion
Authors: Hallgren Willow , Schlosser C. Adam , Monier Erwan , Kicklighter David , Sokolov Andrei , Melillo Jerry
Published: March 2013

A global biofuels program will potentially lead to intense pressures on land supply and cause widespread transformations in land use. These transformations can alter the Earth climate system by increasing greenhouse gas (GHG) emissions from land use changes and by changing the reflective and energy exchange characteristics of land ecosystems. Using an integrated assessment model that links an economic model with climate, terrestrial biogeochemistry, and biogeophysics models, we examined the biogeochemical and biogeophysical effects of possible land use changes from an expanded global second‐generation bioenergy program on surface temperatures over the first half of the 21st century. Our integrated assessment model shows that land clearing, especially forest clearing, has two concurrent effects—increased GHG emissions, resulting in surface air warming; and large changes in the land's reflective and energy exchange characteristics, resulting in surface air warming in the tropics but cooling in temperate and polar regions. Overall, these biogeochemical and biogeophysical effects will only have a small impact on global mean surface temperature. However, the model projects regional patterns of enhanced surface air warming in the Amazon Basin and the eastern part of the Congo Basin. Therefore, global land use strategies that protect tropical forests could dramatically reduce air warming projected in these regions.