bluuebunny/crossref_metadata_2025 huggingface dataset:
Flaxseed Cyclolinopeptides: Analysis and Storage Stability
Authors: Aladedunye Felix , Sosinska Ewa , Przybylski Roman
Published: November 2012

Fourteen cyclolinopeptides (CLPs) from flaxseed oil and meal were separated, identified and quantified by HPLC coupled to an Orbitrap MS. The oxidative stability of the cyclolinopeptides was assessed during storage of flaxseed oil and meal. A significant decrease in the amounts of the methionine containing CLPs, namely CLP‐B, CLP‐J and CLP‐M, and a concurrent increase in the amounts of methionine sulfoxide containing CLPs, such as CLP‐C, CLP‐E and CLP‐G were observed. The cyclolinopeptides with two methionine units, CLP‐L and CLP‐M, exhibited the greatest decrease, followed by CLP‐J, the major flaxseed oil bitter taste precursor, and CLP‐B, a biologically active cyclolinopeptide. At the end of the storage period, the amount of the bitter CLP‐E increased fourfold in the oil while the immunosuppressive cyclolinopeptides A remained unchanged. No significant changes in the amount of each of the CLPs were observed in the stored flaxseed meals. A fast and reliable procedure has been developed for quantitative analysis of cyclolinopeptides. Due to the high predisposition of methionine containing cyclolinopeptides to oxidation and the easiness of CLPs’ quantification with the proposed method, it is possible to reliably assess the extent of flaxseed meal and oil oxidation.
NTPDase and 5′‐nucleotidase activities from synaptosomes and platelets of rats exposed to cadmium and treated with N‐acetylcysteine
Authors: Gonçalves Jamile F. , Spanevello Roselia M. , Fiorenza Amanda M. , Mazzanti Cinthia M. , Bagatini Margarete D. , da Rosa Cíntia S. , Becker Lara V. , da Costa Pauline , Abdalla Fátima H. , Morsch Vera M. , Schetinger Maria Rosa C.
Published: November 2012

The purpose of the present investigation was to evaluate the hydrolysis of adenine nucleotides on synaptosomes and platelets obtained from rats exposed to cadmium (Cd) and treated with N‐acetylcysteine (NAC). Rats received Cd (2 mg/kg) and NAC (150 mg/kg) by gavage every other day for 30 days. Animals were divided into four groups (n = 4–6): control/saline, NAC, Cd, and Cd/NAC. The results of this study demonstrated that NTPDase and 5′‐nucleotidase activities were increased in the cerebral cortex synaptosomes of Cd‐poisoned rats, and NAC co‐treatment reversed these activities to the control levels. In relation to hippocampus synaptosomes, no differences on the NTPDase and 5′‐nucleotidase activities of Cd‐poisoned rats were observed and only the 5′‐nucleotidase activity was increased by the administration of NAC per se. In platelets, Cd‐intoxicated rats showed a decreased NTPDase activity and no difference in the 5′‐nucleotidase activity; NAC co‐treatment was inefficient in counteracting this undesirable effect. Our findings reveal that adenine nucleotide hydrolysis in synaptosomes and platelets of rats were altered after Cd exposure leading to a compensatory response in the central nervous system and acting as a modulator of the platelet activity. NAC was able to modulate the purinergic system which is interesting since the regulation of these enzymes could have potential therapeutic importance. Thus, our results reinforce the importance of the study of the ecto‐nucleotidases pathway in poisoning conditions and highlight the possibility of using antioxidants such as NAC as adjuvant against toxicological conditions.
Predictors of Patient‐Reported Recovery From Motor or Sensory Deficits Two Years After Acute Symptomatic Lumbar Disk Herniation
Authors: Suri Pradeep , Rainville James , Gellhorn Alfred
Published: November 2012

Objective

To determine the prevalence of patient‐reported recovery from motor or sensory deficits over 2 years of follow‐up after acute symptomatic lumbar disk herniation and to identify predictors of perceived recovery.

Design

A prospective inception cohort.

Setting

An outpatient spine clinic.

Patients

Consecutive adults with lumbosacral radicular syndrome (onset ≤12 weeks) due to symptomatic lumbar disk herniation, confirmed by magnetic resonance imaging: 95 patients with a baseline motor deficit by physical examination and 59 patients with a baseline sensory deficit by physical examination.

Methods

The patients received individualized nonsurgical treatment or, in a minority of cases, surgical treatment. All of the patients underwent a standardized baseline neurologic examination, including motor and sensory testing. Patients with a motor or sensory deficit at the baseline examination reported on whether they perceived persisting weakness or sensory deficits at 1‐ and 2‐year follow‐up. We calculated the 1‐ and 2‐year prevalence of patient‐reported persisting weakness or sensory deficits. We examined factors associated with perceived recovery from motor or sensory deficits by using bivariate analyses and multivariate logistic regression.

Results

Among patients with a baseline motor deficit, the prevalence of patient‐reported continuing weakness was 38% at 1 year and 25% at 2 years. Among patients with a baseline sensory deficit, the prevalence of patient‐reported continuing sensory deficits was 53% at 1 year and 47% at 2 years. A positive straight leg raise test (odds ratio [OR] 0.26 [95% confidence interval (CI) 0.08‐0.83]) and opioid use (OR 0.24 [95% CI 0.06‐0.83]) were independently and negatively predictive of patient‐reported motor recovery. Female gender was independently and negatively predictive of patient‐reported sensory recovery (OR 0.20 [95% CI 0.04‐0.99]).

Conclusions

Patient‐reported recovery from motor deficits after lumbar disk herniation occurs for 75% of patients over 2 years, but recovery from sensory deficits over this time frame occurs in only 53% of patients. A positive straight‐leg raise test and female gender may predict poor recovery from motor and sensory deficits, respectively.
Age and significance of the Quaternary cemented deposits of the Duje Valley (Picos de Europa, Northern Spain)
Authors: Villa Elisa , Stoll Heather , Farias Pedro , Adrados Luna , Edwards R. Lawrence , Cheng Hai
Published: November 2012

Cemented calcareous breccias appear in the Picos de Europa (Cantabrian Mountains, Spain) resting on glacially abraded surfaces and covered by moraines. U/Th dating of the calcite coating the clasts was successful in two samples, the oldest one indicating that the breccias accumulated during or prior to Marine Isotope Stage (MIS) 11, and the youngest indicating later cementation during MIS 8. The former introduces a limit for the age of the glaciation preceding the breccias, which cannot correspond to an event younger than MIS 12. This is the oldest absolute age so far obtained for intercalated glacial/interglacial deposits of the Iberian Peninsula.
The relationship between zinc intake and serum/plasma zinc concentration in adults: a systematic review and dose–response meta-analysis by the EURRECA Network
Authors: Lowe Nicola M. , Medina Marisol Warthon , Stammers Anna-Louise , Patel Sujata , Souverein Olga W. , Dullemeijer Carla , Serra-Majem Lluis , Nissensohn Mariela , Hall Moran Victoria
Published: November 2012

Dietary Zn recommendations vary widely across Europe due to the heterogeneity of approaches used by expert panels. Under the EURopean micronutrient RECommendations Aligned (EURRECA) consortium a protocol was designed to systematically review and undertake meta-analyses of research data to create a database that includes ‘best practice’ guidelines which can be used as a resource by future panels when setting micronutrient recommendations. As part of this process, the objective of the present study was to undertake a systematic review and meta-analysis of previously published data describing the relationship between Zn intake and status in adults. Searches were performed of literature published up to February 2010 using MEDLINE, Embase and the Cochrane Library. Data extracted included population characteristics, dose of Zn, duration of study, dietary intake of Zn, and mean concentration of Zn in plasma or serum at the end of the intervention period. An intake–status regression coefficient ($\circ {>\beta }$) was estimated for each individual study, and pooled meta-analysis undertaken. The overall pooled $\circ {>\beta }$ for Zn supplementation on serum/plasma Zn concentrations from randomised controlled trials and observational studies was 0·08 (95 % CI 0·05, 0·11; P < 0·0001; I2 84·5 %). An overall $\circ {>\beta }$ of 0·08 means that for every doubling in Zn intake, the difference in Zn serum or plasma concentration is $2^{ \circ {>\beta }}$ (20·08 = 1·06), which is 6 %. Whether the dose–response relationship, as provided in the present paper, could be used as either qualitative or quantitative evidence to substantiate the daily Zn intake dose necessary to achieve normal or optimal levels of biomarkers for Zn status remains a matter of discussion.
An in vitro investigation of species-dependent intestinal transport of selenium and the impact of this process on selenium bioavailability
Authors: Thiry Celine , Ruttens Ann , Pussemier Luc , Schneider Yves-Jacques
Published: November 2012

A range of Se species has been shown to occur in a variety of different foodstuffs. Depending on its speciation, Se is more or less bioavailable to human subjects. In the present study, the role of speciation as a determinant of Se bioavailability was addressed with an investigation of species-specific mechanisms of transport at the intestinal level. The present work focused on four distinct Se compounds (selenate (Se(VI)), selenite (Se(IV)), selenomethionine (SeMet) and methylselenocysteine (MeSeCys)), whose intestinal transport was mimicked through an in vitro bicameral model of enterocyte-like differentiated Caco-2 cells. Efficiency of Se absorption was shown to be species dependent (SeMet>MeSeCys>Se(VI)>Se(IV)). In the case of SeMet, MeSeCys and Se(VI), the highly polarised passage from the apical to basolateral pole indicated that a substantial fraction of transport was transcellular, whilst results for Se(IV) indicated paracellular diffusion. Passage of the organic Se species (SeMet and MeSeCys) became saturated after 3 h, but no such effect was observed for the inorganic species. In addition, SeMet and MeSeCys transport was significantly inhibited by their respective S analogues methionine and methylcysteine, which suggests a common transport system for both kinds of compounds.
Cigarette smoking, psychopathology and cognitive function in first-episode drug-naive patients with schizophrenia: a case-control study
Authors: Zhang X. Y. , Chen D. C. , Xiu M. H. , Haile C. N. , He S. C. , Luo X. , Zuo L. , Rosenheck R. , Kosten T. A. , Kosten T. R.
Published: November 2012

Background

Although patients with chronic schizophrenia have substantially higher smoking rates than either the general population or patients with other mental illnesses, drug-naive patients with a first episode of schizophrenia have received little systemic study. This study examined smoking rates, the association between smoking and symptom severity and cognitive function in Chinese first-episode schizophrenia (FES) patients using cross-sectional and case-control designs.

Method

Two hundred and forty-four drug-naive FES patients and 256 healthy controls matched for gender, age and education completed the Fagerström Test for Nicotine Dependence (FTND) and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Patients were also rated on the Positive and Negative Symptom Scale (PANSS).

Results

The rate and quantity of smoking were not significantly higher among FES patients compared to the general population. Among patients, smokers scored higher than non-smokers on the total PANSS and the positive symptom subscale scores. There were no significant associations between cognitive function and smoking in either FES patients or healthy controls.

Conclusions

In contrast to studies in patients with chronic schizophrenia, drug-naive FES patients did not smoke more frequently than the general population. Furthermore, patients with psychotic disorders who smoked did not exhibit significant cognitive differences compared with those who did not smoke. However, smoking may have other detrimental effects on physical and mental health, for example on positive symptoms.
Facial emotion recognition in borderline personality disorder
Authors: Daros A. R. , Zakzanis K. K. , Ruocco A. C.
Published: November 2012

Background

Emotion dysregulation represents a core symptom of borderline personality disorder (BPD). Deficits in emotion perception are thought to underlie this clinical feature, although studies examining emotion recognition abilities in BPD have yielded inconsistent findings.

Method

The results of 10 studies contrasting facial emotion recognition in patients with BPD (n = 266) and non-psychiatric controls (n = 255) were quantitatively synthesized using meta-analytic techniques.

Results

Patients with BPD were less accurate than controls in recognizing facial displays of anger and disgust, although their most pronounced deficit was in correctly identifying neutral (no emotion) facial expressions. These results could not be accounted for by speed/accuracy in the test-taking approach of BPD patients.

Conclusions

Patients with BPD have difficulties recognizing specific negative emotions in faces and may misattribute emotions to faces depicting neutral expressions. The contribution of state-related emotion perception biases to these findings requires further clarification.
A NOTE ON ENDOGENOUS PROPAGATION IN ONE-SECTOR BUSINESS CYCLE MODELS WITH DYNAMIC COMPLEMENTARITIES
Authors: Hung Mao-Wei , Wu Shue-Jen
Published: November 2012

When the production function includes dynamic complementarities and a Cobb--Douglas form, dynamic complementarities are an endogenous propagation mechanism of shocks. The proposed model explains several stylized facts of aggregate variables of interest, including (i) hump-shaped impulse response functions, (ii) positively autocorrelated growth rates of aggregate variables, and (iii) correlation coefficients of forecastable movements in aggregate variables.
Circulation in Drake Passage revisited using new current time series and satellite altimetry: 1. The Yaghan Basin
Authors: Ferrari Ramiro , Provost Christine , Renault Alice , Sennéchael Nathalie , Barré Nicolas , Park Young‐Hyang , Lee Jae Hak
Published: November 2012

The complex bathymetry of the Drake Passage and the meridional extent of the Shackleton Fracture Zone, in particular, force the Subantarctic Front (SAF) and the Polar Front (PF) to veer to the north, and the flow of the Antarctic Circumpolar Current concentrates in the Yaghan Basin. We have studied the circulation in the Yaghan Basin, using 3 years of velocity data (January 2006–March 2009) at five mooring sites and 18 years of satellite altimetry data. Mean velocities at our mooring sites show a dominant eastward component which decreases with depth, as expected, with a notable exception in the center of the Yaghan Basin, where mean velocities reveal a dominant westward component increasing with depth. The mooring data suggest the existence of a permanent, strong deep cyclonic circulation over the Yaghan seafloor depression in the northeastern part of the Yaghan Basin. The in situ data provide the first opportunity to compare altimetry‐derived velocities with high temporal resolution near‐surface current meter velocities in a large eddy kinetic energy environment at high latitudes. Globally, altimetry‐derived velocities compare rather well with the in situ velocities at 500 m depth both in strength and direction. Correlations are high between the in situ velocities and the surface velocities derived from satellite altimetric data. Mean sea level estimates lead to reasonable mean surface velocities with, however, a slight underestimation of the mean velocity at the mean location of the SAF on the continental slope and a more important underestimation of the westward current in the center of the Yaghan Basin. A dominant mode of velocity variations (23% of the variance) is observed both in the in situ and satellite data, corresponding to a strong southward meander of the SAF upstream of the mooring line and a northward meander of the PF downstream of the latter. The 18 yearlong altimetry time series shows that the mode is robust and has a strong semiannual component.
Direct radiative effects of sea salt for the Mediterranean region under conditions of low to moderate wind speeds
Authors: Lundgren K. , Vogel B. , Vogel H. , Kottmeier Ch.
Published: November 2012

This study deals with the direct radiative effect of sea salt on the regional scale, within both the shortwave and longwave ranges. The COSMO‐ART model system has been extended and applied for a large part of Europe and adjacent waters within this investigation. For the radiation calculations, we determined the sea salt optical properties based on Mie calculations, giving the optical properties for the three sea salt modes and eight spectral intervals. The simulated sea salt aerosol optical depth is found to show strong dependence on the 10 m wind speed under cloud‐free conditions. This relation is best represented by a power law fit and compares well with satellite observations. For clear‐sky conditions, the simulated sea salt direct radiative effects on the shortwave and longwave radiative budgets are approximately of the same order of magnitude, but with opposite signs. This causes the net radiative effect to approach zero, which leads to a low impact on the temperature for this area.
On the formation and evolution of the Pannonian Basin: Constraints derived from the structure of the junction area between the Carpathians and Dinarides
Authors: Matenco L. , Radivojević D.
Published: November 2012

The large number and distribution of rollback systems in Mediterranean orogens infer the possibility of interacting extensional back‐arc deformation driven by different slabs. The formation of the Pannonian back‐arc basin is generally related to the rapid Miocene rollback of a slab attached to the European continent. A key area of the entire system that is neglected by kinematic studies is the connection between the South Carpathians and Dinarides. In order to derive an evolutionary model, we interpreted regional seismic lines traversing the entire Serbian part of the Pannonian Basin. The observed deformation is dominantly expressed by the formation of Miocene extensional detachments and (half) grabens. The extensional geometries and associated synkinematic sedimentation that migrated in time and space allow the definition of a continuous and essentially asymmetric early to late Miocene extensional evolution. This evolution was followed by the formation of few uplifted areas during the subsequent latest Miocene–Quaternary inversion. The present‐day extensional geometry changing the strike across the basin is an effect of the clockwise rotation of the South Carpathians and Apuseni Mountains in respect to the Dinarides. Our study infers that the Carpathian rollback is not the only mechanism responsible for the formation of the Pannonian Basin; an additional middle Miocene rollback of a Dinaridic slab is required to explain the observed structures. Furthermore, the study provides constraints for the pre‐Neogene orogenic evolution of this junction zone, including the affinity of major crustal blocks, obducted ophiolitic sequences and the Sava suture zone.
Cellular and molecular interactions of mesenchymal stem cells in innate immunity
Authors: Maria Spaggiari Grazia , Moretta Lorenzo
Published: November 2012

In recent years, human mesenchymal stem/stromal cells (MSC) have attracted major attention for their possible clinical applications. In addition to their tissue regenerative capacity, they display immune‐modulatory properties for which they have been used in the treatment of acute graft‐versus‐host disease and autoimmune diseases. Various studies have analyzed the inhibitory effect exerted by MSC on cells belonging to acquired or to innate immunity. In this context, MSC have been shown to inhibit proliferation and function of natural killer (NK) cells and to hinder the generation of dendritic cells and macrophages, thus interfering with inflammatory processes and with the generation of type I immune responses. In addition, MSC promote the differentiation of regulatory cells and participate in the regeneration of tissues damaged as a consequence of the inflammatory process. Different molecular mechanisms are involved in the immunosuppressive effect. Further investigation on the biology of MSC and on the regulatory events involved in their functional activities can help to optimize their use in clinical practice.
Statistical analysis of kinetic energy entrainment in a model wind turbine array boundary layer
Authors: Hamilton Nicholas , Suk Kang Hyung , Meneveau Charles , Bayoán Cal Raúl
Published: November 2012

For large wind farms, kinetic energy must be entrained from the flow above the wind turbines to replenish wakes and enable power extraction in the array. Various statistical features of turbulence causing vertical entrainment of mean-flow kinetic energy are studied using hot-wire velocimetry data taken in a model wind farm in a scaled wind tunnel experiment. Conditional statistics and spectral decompositions are employed to characterize the most relevant turbulent flow structures and determine their length-scales. Sweep and ejection events are shown to be the largest contributors to the vertical kinetic energy flux, although their relative contribution depends upon the location in the wake. Sweeps are shown to be dominant in the region above the wind turbine array. A spectral analysis of the data shows that large scales of the flow, about the size of the rotor diameter in length or larger, dominate the vertical entrainment. The flow is less incoherent below the array, causing decreased vertical fluxes there. The results show that improving the rate of vertical kinetic energy entrainment into wind turbine arrays is a standing challenge and would require modifying the large-scale structures of the flow. Such an optimization would in the future aid recovery of the wind turbine wake towards conditions corresponding to the undisturbed atmospheric boundary layer.
Fluorescence emission of Ca-atom from photodissociated Ca2 in Ar-doped helium droplets. I. Experimental
Authors: Masson A. , Briant M. , Hernando A. , Halberstadt N. , Mestdagh J.-M. , Gaveau M.-A.
Published: November 2012

The Ca2 → Ca(4s4p 1P) + Ca(4s2 1S) photodissociation was investigated in a He droplet isolation experiment where the droplets are doped by Ar atoms. Fluorescence spectra associated with the Ca(4s4p 1P → 4s2 1S) emission were recorded as a function of the average number of Ar atoms per droplet. Three contributions were observed depending on whether the emitting Ca atoms are free, bound to helium atoms or bound to argon atoms. Moreover, the full Ca(4s4p 1P → 4s2 1S) fluorescence emission was recorded as a function of the wavelength of the photodissociation laser, hence providing the action spectrum of the Ca2 → Ca(4s4p 1P) + Ca(4s2 1S) process. The latter spectrum suggests that in He droplets doped by argon, Ca atoms are attracted inside the droplet where they associate as Ca2. Full analysis of the spectra indicate that the emission of Ca bound to a single Ar atom is redshifted by 94 cm−1 with respect to the emission of free Ca.
Transport properties of suspensions–critical assessment of Beenakker-Mazur method
Authors: Makuch Karol , Cichocki Bogdan
Published: November 2012

The Beenakker-Mazur method of calculation of transport coefficients for suspensions has been analyzed. The analysis relies on calculation of the hydrodynamic function and the effective viscosity with higher accuracy and comparison of these characteristics to the original Beennakker-Mazur results. Comparison to numerical simulations is also given. Our calculations go along with the idea of Beenakker and Mazur, but avoid unnecessary approximations. Our higher accuracy results differ significantly from results obtained initially by Beenakker and Mazur for volume fractions ϕ > 25%. Moreover, our results agree with the precise numerical simulations of Abade and Ladd for volume fractions ϕ < 15% and volume fractions ϕ ≈ 45%, whereas for volume fractions 15% < ϕ < 40%, we observe pronounced discrepancies.
Fumed silica concentration effect on structure and dielectric properties of a styrene-cross-linked unsaturated polyester resin
Authors: Gorelov B. M. , Polovina O. I. , Gorb A. M. , Dacko S. , Kostrzewa M. , Ingram A.
Published: November 2012

Concentration effects of a high-reactive-surface nanosized SiO2 filler on structure and dielectrical properties of a styrene-cross-linked polyester resin have been experimentally studied. Thermal desorption mass-spectroscopy, IR-spectroscopy, dielectric spectroscopy, and positron annihilation lifetime spectroscopy were used to determine an atomic content of thermal destruction products, IR-reflection spectra, complex dielectric permittivity, and a nature of positron traps as function of filler content in the polymer matrix. Interaction between active surface centers of SiO2-nanoparticles and atoms of polyester chains and styrene molecules gives the non-monotonous influence on the structure of polyester chains, macromolecule polarity, dielectric parameters and the number of positronium nanotraps.
General dislocation image stress of anisotropic cubic thin film
Authors: Wu Wenwang , Schäublin Robin , Chen Jiachao
Published: November 2012

A calculation method for accurately computing the displacement, image stress, and image energy induced by defects, such as cavities, precipitates, finite dislocation segments, and dislocation loops, in a free-standing anisotropic thin crystal film is presented. The anisotropic image stress is derived in the Fourier space from the standing Christoffel stress equilibrium equation for anisotropic materials, relying on the elastic parameters, the crystallographic orientation of the film and the considered defect. The image stress corresponds to the traction stress field, describing the stress field at the free surface. The latter is the stress induced by the same defects in an infinite medium evaluated at the location of the free surface. This method is applied to pure bcc Fe semi infinite single crystals and thin crystal films. The calculation results show that a stronger image stress induced in-plane and out-of plane displacement difference is produced with the anisotropic elasticity for bcc Fe, relative to the isotropic case, calculated by either Voigt or Reuss methods. It confirms that anisotropy has a strong influence on the image stress induced 3D displacement fields.
Broadband Purcell enhanced emission dynamics of quantum dots in linear photonic crystal waveguides
Authors: Laucht A. , Günthner T. , Pütz S. , Saive R. , Frédérick S. , Hauke N. , Bichler M. , Amann M.-C. , Holleitner A. W. , Kaniber M. , Finley J. J.
Published: November 2012

The authors investigate the spontaneous emission dynamics of self-assembled InGaAs quantum dots embedded in GaAs photonic crystal waveguides. For an ensemble of dots coupled to guided modes in the waveguide, we report spatially, spectrally, and time-resolved photoluminescence measurements, detecting normal to the plane of the photonic crystal. For quantum dots emitting in resonance with the waveguide mode, an ∼21× enhancement of photoluminescence intensity is observed as compared to dots in the unprocessed region of the wafer. This enhancement can be traced back to the Purcell enhanced emission of quantum dots into leaky and guided modes of the waveguide with moderate Purcell factors up to ∼4×. Emission into guided modes is shown to be efficiently scattered out of the waveguide within a few microns, contributing to the out-of-plane emission and allowing the use of photonic crystal waveguides as broadband, efficiency-enhancing structures for surface-emitting diodes or single photon sources.
Effect of uniaxial stress on electroluminescence, valence band modification, optical gain, and polarization modes in tensile strained p-AlGaAs/GaAsP/n-AlGaAs laser diode structures: Numerical calculations and experimental results
Authors: Bogdanov E. V. , Minina N. Ya. , Tomm J. W. , Kissel H.
Published: November 2012

The effects of uniaxial compression in [110] direction on energy-band structures, heavy and light hole mixing, optical matrix elements, and gain in laser diodes with “light hole up” configuration of valence band levels in GaAsP quantum wells with different widths and phosphorus contents are numerically calculated. The development of light and heavy hole mixing caused by symmetry lowering and converging behavior of light and heavy hole levels in such quantum wells under uniaxial compression is displayed. The light or heavy hole nature of each level is established for all considered values of uniaxial stress. The results of optical gain calculations for TM and TE polarization modes show that uniaxial compression leads to a significant increase of the TE mode and a minor decrease of the TM mode. Electroluminescence experiments were performed under uniaxial compression up to 5 kbar at 77 K on a model laser diode structure (p-AlxGa1−xAs/GaAs1−yPy/n-AlxGa1−xAs) with y = 0.16 and a quantum well width of 14 nm. They reveal a maximum blue shift of 27 meV of the electroluminescence spectra that is well described by the calculated change of the optical gap and the increase of the intensity being referred to a TE mode enhancement. Numerical calculations and electroluminescence data indicate that uniaxial compression may be used for a moderate wavelength and TM/TE intensity ratio tuning.
Effect of N2 dielectric barrier discharge treatment on the composition of very thin SiO2-like films deposited from hexamethyldisiloxane at atmospheric pressure
Authors: Reuter R. , Gherardi N. , Benedikt J.
Published: November 2012

The continuous deposition of thin SiO2-like films by means of a dielectric barrier discharge with helium or nitrogen gas with small admixture of hexamethyldisiloxane (HMDSO) has been compared to a layer-by-layer deposition process, in which a very thin (0.7 nm and 2.5 nm) films are deposited from HMDSO precursor and treated afterwards by a pure N2 dielectric barrier discharge (DBD). Presented results clearly show that a carbon-free SiO2-like films can be obtained in the latter process, even if the continuous deposition led to carbon-rich material. Surface reactions of N2-DBD generated excited species (metastables, ions, or possibly photons) with surface bonded carbon are responsible for this effect. Moreover, OH-free and oxidation-resistant films can be produced even at the room substrate temperature.
Trapping of free electrons in III-V superlattices
Authors: Laikhtman B.
Published: November 2012

Non-radiative trapping of electrons to deep traps in III-V superlattices is studied. An advancement in the technique of the calculation made it possible to avoid some approximation used in earlier calculation and to obtain a simpler, more precise, and clear results that extend applicability of the theory to narrow band gap materials and superlattices. It is shown that the non-radiative trapping rate in regular Huang-Rhys model has an activation temperature dependence with the activation energy equal to a portion of the phonon energy. The trapping to deep states can be accompanied with emission of phonons of different modes with different frequencies that can significantly reduce the activation energy. I argue that the role of superlattice phonons is relatively small except very low temperature where processes with their participation can have zero activation energy. A specific attention is paid in the paper to a qualitative explanation of every step of the calculation and details of the result. The theoretical results are used for understanding of recently measured temperature dependence of the minority carrier lifetime in InAs/GaSb superlattices.
Dynamic scaling in magnetophoretic separation
Authors: Amira Wael Ben , Malek Abid , Ali M'chirgui
Published: November 2012

Using numerical solutions of the Langevin equations, to simulate a magnetic separation of colloidal suspensions under an external magnetic-field gradient, we show the existence of a regime of dynamic scaling. We find that the separation time depends strongly on the size (or length) of aggregates taking place in the separation process. In the irreversible aggregation regime, we show that linear chains of particles steadily grow and their average size, S, increases with time as a power low. The chain-size (s) distribution-function (cs) approaches (for long times) the following scaling form cs(t)∝s−2f(s/S). The exponent, z, of the mean chain size S(t)∝tz is compatible with Smoluchowski's coagulation equation, with a homogeneous kernel, even if the separation is a process with particle migration. We also show that the regime corresponding to the dynamic scaling is limited in time due to the separation. Furthermore, we find a characteristic time, which we identify as a similarity variable, and we relate it to the separation time.
Understanding adsorption-induced structural transitions in metal-organic frameworks: From the unit cell to the crystal
Authors: Triguero Carles , Coudert François-Xavier , Boutin Anne , Fuchs Alain H. , Neimark Alexander V.
Published: November 2012

Breathing transitions represent recently discovered adsorption-induced structural transformations between large-pore and narrow-pore conformations in bi-stable metal-organic frameworks such as MIL-53. We present a multiscale physical mechanism of the dynamics of breathing transitions. We show that due to interplay between host framework elasticity and guest molecule adsorption, these transformations on the crystal level occur via layer-by-layer shear. We construct a simple Hamiltonian that describes the physics of host-host and host-guest interactions on the level of unit cells and reduces to one effective dimension due to the long-range elastic cell-cell interactions. We then use this Hamiltonian in Monte Carlo simulations of adsorption-desorption cycles to study how the behavior of unit cells is linked to the transition mechanism at the crystal level through three key physical parameters: the transition energy barrier, the cell-cell elastic coupling, and the system size.
An all optical mapping of the strain field in GaAsN/GaAsN:H wires
Authors: Geddo M. , Giulotto E. , Grandi M. S. , Patrini M. , Trotta R. , Polimeni A. , Capizzi M. , Martelli F. , Rubini S.
Published: November 2012

GaAsN/GaAsN:H heterostructures were made by an in-plane selective hydrogen incorporation controlled by H-opaque metallic masks. The strain field and hydrogen distributions in GaAsN micro-sized wires thus obtained have been mapped by an all optical procedure that combines micro-Raman scattering and photoreflectance spectroscopy. The strain field is related to the formation of N-H complexes along the hydrogen diffusion profile with an ensuing expansion of the GaAsN lattice whose patterning generates an anisotropic stress in the sample growth plane. These results highlight a powerful non-invasive tool to simultaneously determine both the H diffusion profile and the related strain field distribution.
Review of Spanish renewable energy policy to encourage investment in solar photovoltaic
Authors: Zeeshan Shirazi Sana , Mohammad Zeeshan Shirazi Syed
Published: November 2012

The Spanish renewable energy sector has experienced phenomenal growth over the past decade due to implementation of regulatory frameworks that have encouraged the rapid deployment of some renewable energy technologies particularly solar photovoltaic (PV), wind, and biomass. But the unstable regulatory frameworks, price, and quantity caps on renewable technologies and recent initiative of temporary suspension of subsidies for any new solar, wind, cogeneration or waste incineration projects have declined the growth of production of electricity from renewable energy sources (RES-E). The aim of this paper is to provide the current situation of promotion measurers for RES-E particularly for solar PV in Spain and regulatory changes since the feed-in-tariff was put in place in Spanish solar market. The paper also provides a critical analysis of the Spanish policy instruments and regulatory frameworks that contributed in the tremendous growth of solar PV. It also analyses the new policy instruments necessary to achieve declared 2020 RES-E targets.
Nonlinear charge transport in the helicoidal DNA molecule
Authors: Dang Koko A. , Tabi C. B. , Ekobena Fouda H. P. , Mohamadou A. , Kofané T. C.
Published: November 2012

Charge transport in the twist-opening model of DNA is explored via the modulational instability of a plane wave. The dynamics of charge is shown to be governed, in the adiabatic approximation, by a modified discrete nonlinear Schrödinger equation with next-nearest neighbor interactions. The linear stability analysis is performed on the latter and manifestations of the modulational instability are discussed according to the value of the parameter α, which measures hopping interaction correction. In so doing, increasing α leads to a reduction of the instability domain and, therefore, increases our chances of choosing appropriate values of parameters that could give rise to pattern formation in the twist-opening model. Our analytical predictions are verified numerically, where the generic equations for the radial and torsional dynamics are directly integrated. The impact of charge migration on the above degrees of freedom is discussed for different values of α. Soliton-like and localized structures are observed and thus confirm our analytical predictions. We also find that polaronic structures, as known in DNA charge transport, are generated through modulational instability, and hence reinforces the robustness of polaron in the model we study.
High quality AlN grown on double layer AlN buffers on SiC substrate for deep ultraviolet photodetectors
Authors: Al tahtamouni T. M. , Lin J. Y. , Jiang H. X.
Published: November 2012

High quality AlN epilayers were grown on SiC substrates using double layer AlN buffers growth method by metal organic chemical vapor deposition and exploited as active deep ultraviolet optoelectronic materials through the demonstration of AlN Schottky barrier photodetectors. The grown AlN epilayers have smooth surfaces, low etch-pit density, narrow width of x-ray rocking curves, and strong band edge photoluminescence emission with low impurity emissions. AlN Schottky photodetectors are shown to possess outstanding features including extremely low dark current and high breakdown voltage.
Magneto-resistance up to 60 Tesla in topological insulator Bi2Te3 thin films
Authors: Zhang S. X. , McDonald R. D. , Shekhter A. , Bi Z. X. , Li Y. , Jia Q. X. , Picraux S. T.
Published: November 2012

We report magneto-transport studies of topological insulator Bi2Te3 thin films grown by pulsed laser deposition. A non-saturating linear-like magneto-resistance (MR) is observed at low temperatures in the magnetic field range from a few Tesla up to 60 Tesla. We demonstrate that the strong linear-like MR at high field can be well understood as the weak antilocalization phenomena described by Hikami-Larkin-Nagaoka theory. Our analysis suggests that in our system, a topological insulator, the elastic scattering time can be longer than the spin-orbit scattering time. We briefly discuss our results in the context of Dirac Fermion physics and “quantum linear magnetoresistance.”
Use of solar thermal energy in the hydrodistillation of essential oil
Authors: Maiti Subarna , Bhatt Chitrangi , Patel Pankaj , Ghosh Pushpito K.
Published: November 2012

There has been rising demand in recent years for environment friendly technologies which has spurred interest in sustainable energy solutions. The use of solar radiation in place of fossil fuel-derived thermal energy to extract essential oils in decentralized manner is one such potentially attractive proposition. The present work reports such a study for hydrodistillation of essential oil from fresh orange peels. The distillation was carried out in the absorber tube of a square parabolic trough concentrator of 1.3 m2 collector aperture area. 400–500 g of fresh peels was processed per batch and the limonene content in the crude oil was in the range of 86% to 90% while the yield of the oil varied from 0.49% to 2.16% (w/w). The volume of distillate was found to correlate nicely with the average absorber tube temperature over the duration of the experiment and the maximum hydrodistillation efficiency was computed to be 8.37%. The yield of oil also showed a good correlation with the absorber tube temperature. The tube temperature, in turn, was controlled by the beam radiation, ambient temperature and wind speed.
Interplay between non-bridging oxygen, triclusters, and fivefold Al coordination in low silica content calcium aluminosilicate melts
Authors: Jakse N. , Bouhadja M. , Kozaily J. , Drewitt J. W. E. , Hennet L. , Neuville D. R. , Fischer H. E. , Cristiglio V. , Pasturel A.
Published: November 2012

In the present work the structural properties of low silica content calcium aluminosilicate melts with concentration ratio CaO/Al2O3 = 1 are investigated in the liquid and undercooled states by neutron diffraction experiments and ab initio molecular dynamics simulations. The results show the presence of AlO5 units and triclusters as well as non-bridging oxygen in the fully charge balanced compositions. Moreover, our findings allow us to identify a possible interplay between these structural units. Finally, we discuss the influence of these defective structural units on the properties of tetrahedral network and more particularly their implication on the evolution of the viscosity and the fragility.
Rare earth doped Si-rich ZnO for multiband near-infrared light emitting devices
Authors: Francesco Pecora Emanuele , Murphy Thomas I. , Dal Negro Luca
Published: November 2012

We demonstrate a light emitting material platform based on rare-earth doping of Si-rich ZnO thin films by magnetron sputtering, and we investigate the near-infrared emission properties under both optical and electrical injection. Er and Nd radiative transitions were simultaneously activated due to energy transfer via the ZnO direct bandgap and its luminescent defect centers. Moreover, by incorporating Si atoms, we demonstrate Si-mediated enhancement of photoluminescence in Er-doped ZnO and electroluminescence. These results pave the way to novel Si-compatible light emitters that leverage the optically transparent and electrically conductive ZnO matrix for multiband near-IR telecom and bio-compatible applications.
Spin-wave propagation and transformation in a thermal gradient
Authors: Obry Björn , Vasyuchka Vitaliy I. , Chumak Andrii V. , Serga Alexander A. , Hillebrands Burkard
Published: November 2012

The influence of a thermal gradient on the propagation properties of externally excited dipolar spin waves in a magnetic insulator waveguide is investigated. It is shown that spin waves propagating towards a colder region along the magnetization direction continuously reduce their wavelength. The wavelength increase of a wave propagating into a hotter region was utilized to realize its decomposition in the partial waveguide modes which are reflected at different locations. This influence of temperature on spin-wave properties is mainly caused by a change in the saturation magnetization and yields promising opportunities for the manipulation of spin waves in spin-caloritronic applications.
Graphene-GaAs/AlxGa1−xAs heterostructure dual-function field-effect transistor
Authors: Tang Chiu-Chun , Li Ming-Yang , Li L. J. , Chi C. C. , Chen Jeng-Chung
Published: November 2012

We have integrated chemical vapor-deposited graphene and GaAs/AlxGa1−xAs heterostructure into a hybrid field effect transistor (FET). Depending on the operation scheme, graphene can be utilized either as a gate electrode for a GaAs-based high electron mobility transistor (HEMT) or as a channel material gated by two dimensional electron gas (2DEG) formed in the interface of a heterojunction. Our studies reveal that 2DEG can function as an effective back-electrode to tune the ambipolar effect of graphene. The performance of graphene FET (GFET) is limited by the interface band bending of the heterojunction associated with the gating voltages and the intrinsic surface morphology of GaAs substrate. Our results bode a way to implement HEMT/GEFT-based bi-FET integrated circuits.
Commentary: Powering America with sustainable energy in the 21st century
Authors: Philippidis George
Published: November 2012

The United States continues to rely heavily on foreign oil and coal-based electricity for its transportation and power generation needs, respectively. The perennial lack of a national energy policy has deprived the United States of strong direction towards the development of sustainable domestic energy resources, which are abundantly available, enhance the country's energy security, and reduce its carbon footprint. Technology innovation and economies of scale in the last ten years have made wind, solar thermal, biomass, and natural gas viable and cost-competitive alternatives to highly polluting coal. Biomass and natural gas can produce base-load electricity, whereas wind and solar can address peak demand, when combined with fossils or with energy storage systems like batteries. In vehicles, biofuels and electric motors can rather seamlessly replace gasoline and reduce significantly our dependence on foreign oil. While each form of alternative energy has its own advantages, they can all contribute to economic growth in the 21st century by attracting investment, creating jobs, generating tax revenues, and making the entire US economy more sustainable.
First-principles study on the differences of possible ferroelectric behavior and magnetic exchange interaction between Bi2NiMnO6 and La2NiMnO6
Authors: Jian Zhao Hong , Ming Chen Xiang
Published: November 2012

The differences of possible ferroelectric behavior and magnetic exchange interaction between Bi2NiMnO6 and La2NiMnO6 have been investigated by first-principles calculation. Paying attention to the electronic structures, bonding interaction, and Born effective charges of the two compounds, the calculations reveal that ferroelectric distortion occurs only in Bi2NiMnO6 rather than La2NiMnO6. The calculation also indicates that the Ni-Mn ferromagnetic exchange interaction is weakened in Bi2NiMnO6 compared with that in La2NiMnO6. Thus the present work explains why Bi2NiMnO6 has a lower Curie temperature compared with La2NiMnO6. The mechanism why Bi2NiMnO6 has weaker Ni-Mn ferromagnetic exchange interaction than La2NiMnO6 is explored by considering the Kugel-Khomskii model. Finally, the electric polarizations of Bi2NiMnO6 with ferromagnetic and ferrimagnetic order are estimated to be 18.05 and 19.01 μC/cm2, respectively, indicating the anomaly of electric polarization near the Curie temperature of Bi2NiMnO6.
Nucleosome-depleted chromatin gaps recruit assembly factors for the H3.3 histone variant
Authors: Schneiderman Jonathan I. , Orsi Guillermo A. , Hughes Kelly T. , Loppin Benjamin , Ahmad Kami
Published: November 2012

Most nucleosomes that package eukaryotic DNA are assembled during DNA replication, but chromatin structure is routinely disrupted in active regions of the genome. Replication-independent nucleosome replacement using the H3.3 histone variant efficiently repackages these regions, but how histones are recruited to these sites is unknown. Here, we use an inducible system that produces nucleosome-depleted chromatin at the
Hsp70
genes in
Drosophila
to define steps in the mechanism of nucleosome replacement. We find that the Xnp chromatin remodeler and the Hira histone chaperone independently bind nucleosome-depleted chromatin. Surprisingly, these two factors are only displaced when new nucleosomes are assembled. H3.3 deposition assays reveal that Xnp and Hira are required for efficient nucleosome replacement, and double-mutants are lethal. We propose that Xnp and Hira recognize exposed DNA and serve as a binding platform for the efficient recruitment of H3.3 predeposition complexes to chromatin gaps. These results uncover the mechanisms by which eukaryotic cells actively prevent the exposure of DNA in the nucleus.