bluuebunny/crossref_metadata_2025 huggingface dataset:
Combined control of voltage and frequency of multi‐area multisource system incorporating solar thermal power plant using LSA optimised classical controllers
Authors: Rajbongshi Rumi , Saikia Lalit Chandra
Published: January 2017

This study presents the combined model of automatic load frequency control (ALFC) and automatic voltage regulator (AVR) of a multisource multi‐area system for control of voltage, frequency and tie‐line power. Each area comprises of a solar thermal, thermal and diesel plant. A more realistic system is studied by considering generation rate constraint and governor dead band (GDB) for the thermal plant. Integral (I)‐double derivative (DD) controller with derivative (D) filter (IDDF) is proposed for the combined ALFC and AVR model by considering 1% step load perturbation in area1. The controller parameters are optimised using lightning search algorithm (LSA). The performance of proposed controller is compared with other conventional controllers such as proportional–I (PI), I–D and PI–D. The analysis reveals that the proposed controller outperforms the others in terms of settling time and peak deviations. The comparative performance of various performance indices shows that integral squared error is better than others. Analysis of the effect of GDB with IDDF controller and LSA indicates that the presence of GDB leads to more oscillations in the system dynamics. The sensitivity analysis against the change in magnitude and position of disturbance derived the robustness of the IDDF controller parameters obtained at nominal condition.
New phasor‐based approach for online and fast prediction of generators grouping using decision tree
Authors: Rezaeian Koochi Mohammad Hossein , Esmaeili Saeid , Fadaeinedjad Roohollah
Published: January 2017

Fast and accurate identification of coherent generator groups is helpful in dynamic and transient stability analysis as well as other applications such as controlled islanding. In this study, a new method is presented for predicting the generators’ grouping scheme based on the data measured before and in a short time after the disturbance occurrence. To do that, a classifier model is trained using a training dataset. In the training dataset, the input is the attributes, which are obtained directly or indirectly from the data measured by phasor measurement units. On the other hand, the target in the training dataset is the generators’ grouping, which in this study is calculated using a new method called subtractive technique. In subtractive technique, coherent generator groups are determined based on the generator density values. When the classifier model is built using the training dataset, it can be used for online applications. In this study, the well‐known 68‐bus, 16‐machine power system as well as the Iranian 400 and 230 kV south east regional grid are used as the test systems for investigating the efficiency of proposed coherent group prediction method. Results show that the proposed method can predict the generators’ grouping scheme with high accuracy.
C‐Band Linearly Polarised Textile‐Reflectarray (TRA) Using Conductive Thread
Authors: Tahseen Muhammad M. , Kishk Ahmed A.
Published: January 2017

A linearly polarised C‐band textile‐based reflectarray (TRA) is designed and fabricated using conductive thread. Three fabric samples are selected to be employed in the TRA design. The relative permittivity of the samples under test are extracted using resonance technique. The extracted material parameters are used in designing TRA elements. The reflected wave amplitude and phase curves are obtained by varying the size of the radiating element, resulting in a 340° reflected phase, which is adequate to design the C‐band TRA. A centre‐fed TRA consisting of elements, with antenna size of is intended for the analysis of broadside radiations. A wide band multi‐layer stacked circular patches are used as a feeder. The radiating elements of the TRA are made using the laying technique with conductive thread. The ground (GND) plane is made of shielded fabric. During measurements, it is observed that the shielded fabric is not suitable to be used as a large ground plane. The TRA antenna is measured at 5.8 GHz. The antenna provides a 1‐dB gain bandwidth of 9.3%, the 3‐dB gain bandwidth of more than 22%, SLL of −16 dB, and cross polarisation of −21 dB. A measured total field amplitude and phase distribution verify the planar wavefront conversion from the TRA.
Adaptive reference voltage‐based MPPT technique for PV applications
Authors: Lasheen Mohamed , Abdel Rahman Ali Kamel , Abdel‐Salam Mazen , Ookawara Shinichi
Published: January 2017

The constant voltage (CV) for maximum power point tracking (MPPT) technique is considered one of the most commonly used techniques in the photovoltaic (PV) applications. This study is aimed at proposing an adaptive reference voltage‐based MPPT technique (ARV) to improve the performance of the CV technique by making it adaptable to weather conditions. The RV for MPPT is adapted according to the measured radiation and temperature levels. The operating range of the radiation at a given temperature is divided into number of divisions and the corresponding RV is recorded off‐line in a truth table. The difference between the reference and measured PV voltages is compensated using proportional–integral controller to generate suitable duty ratio to the boost converter. Performance assessment of the CV technique after being improved covers time response, MPPT efficiency, oscillation and stability. The results present performance improvement by fast time response to reach steady‐state value, more stable operation with no oscillation and high MPPT efficiency as compared with the CV technique without the proposed improvement.
Efficient parameter sensitivity computation for spatially extended reaction networks
Authors: Lester C. , Yates C. A. , Baker R. E.
Published: January 2017

Reaction-diffusion models are widely used to study spatially extended chemical reaction systems. In order to understand how the dynamics of a reaction-diffusion model are affected by changes in its input parameters, efficient methods for computing parametric sensitivities are required. In this work, we focus on the stochastic models of spatially extended chemical reaction systems that involve partitioning the computational domain into voxels. Parametric sensitivities are often calculated using Monte Carlo techniques that are typically computationally expensive; however, variance reduction techniques can decrease the number of Monte Carlo simulations required. By exploiting the characteristic dynamics of spatially extended reaction networks, we are able to adapt existing finite difference schemes to robustly estimate parametric sensitivities in a spatially extended network. We show that algorithmic performance depends on the dynamics of the given network and the choice of summary statistics. We then describe a hybrid technique that dynamically chooses the most appropriate simulation method for the network of interest. Our method is tested for functionality and accuracy in a range of different scenarios.
Enhancement of canonical sampling by virtual-state transitions
Authors: Higo Junichi , Kasahara Kota , Dasgupta Bhaskar , Nakamura Haruki
Published: January 2017

A novel method was developed to enhance canonical sampling. A system is divided into virtually introduced sub-states, called “virtual states,” which does not exist in reality. The configuration sampling is achieved by a standard canonical sampling method, the Metropolis Monte Carlo method, and confined in a virtual state for a while. In contrast, inter-virtual state motions are controlled by transition probabilities, which can be set arbitrarily. A simple recursive equation was introduced to determine the inter-virtual state transition probabilities, by which the sampling is enhanced considerably. We named this method “virtual-system coupled canonical Monte Carlo (VcMC) sampling.” A simple method was proposed to reconstruct a canonical distribution function at a certain temperature from the resultant VcMC sampling data. Two systems, a one-dimensional double-well potential and a three-dimensional ligand-receptor binding/unbinding model, were examined. VcMC produced an accurate canonical distribution much more quickly than a conventional canonical Monte Carlo simulation does.
Instability of standing waves for a generalized Choquard equation with potential
Authors: Cheng Zhipeng , Shen Zifei , Yang Minbo
Published: January 2017

We are going to study the standing waves for a generalized Choquard equation with potential −i∂tu−Δu+V(x)u=(1xμ*up)up−2u, in ℝ × ℝ3, where V(x) is a real function, 0 < μ < 3, 2 − μ/3 < p < 6 − μ, and * stands for convolution. Under suitable assumptions on the potential and appropriate frequency ω, the instability of the standing waves u = eiωtφ(x) is investigated.
A simple model for electron dissipation in trapped ion turbulence
Authors: Lesur M. , Cartier-Michaud T. , Drouot T. , Diamond P. H. , Kosuga Y. , Réveillé T. , Gravier E. , Garbet X. , Itoh S.-I. , Itoh K.
Published: January 2017

Trapped ion resonance-driven turbulence is investigated in the presence of electron dissipation in a simplified tokamak geometry. A reduced gyrokinetic bounce-averaged model for trapped ions is adopted. Electron dissipation is modeled by a simple phase-shift δ between density and electric potential perturbations. The linear eigenfunction features a peak at the resonant energy, which becomes stronger with increasing electron dissipation. Accurately resolving this narrow peak in numerical simulation of the initial-value problem yields a stringent lower bound on the number of grid points in the energy space. Further, the radial particle flux is investigated in the presence of electron dissipation, including kinetic effects. When the density gradient is higher than the temperature gradient, and the phase-shift is finite but moderate (δ≈0.02), the particle flux peaks at an order-of-magnitude above the gyro-Bohm estimate. Slight particle pinch is observed for δ<0.003.
Bulk water freezing dynamics on superhydrophobic surfaces
Authors: Chavan S. , Carpenter J. , Nallapaneni M. , Chen J. Y. , Miljkovic N.
Published: January 2017

In this study, we elucidate the mechanisms governing the heat-transfer mediated, non-thermodynamic limited, freezing delay on non-wetting surfaces for a variety of characteristic length scales, Lc (volume/surface area, 3 mm < Lc < 6 mm) using carefully designed freezing experiments in a temperature-controlled, zero-humidity environment on thin water slabs. To probe the effect of surface wettability, we investigated the total time for room temperature water to completely freeze into ice on superhydrophilic (θaapp→  0°), hydrophilic (0° < θa < 90°), hydrophobic (90° < θa < 125°), and superhydrophobic (θaapp→  180°) surfaces. Our results show that at macroscopic length scales, heat conduction through the bulk water/ice layer dominates the freezing process when compared to heat conduction through the functional coatings or nanoscale gaps at the superhydrophobic substrate-water/ice interface. In order to verify our findings, and to determine when the surface structure thermal resistance approaches the water/ice resistance, we fabricated and tested the additional substrates coated with commercial superhydrophobic spray coatings, showing a monotonic increase in freezing time with coating thickness. The added thermal resistance of thicker coatings was much larger than that of the nanoscale superhydrophobic features, which reduced the droplet heat transfer and increased the total freezing time. Transient finite element method heat transfer simulations of the water slab freezing process were performed to calculate the overall heat transfer coefficient at the substrate-water/ice interface during freezing, and shown to be in the range of 1–2.5 kW/m2K for these experiments. The results shown here suggest that in order to exploit the heat-transfer mediated freezing delay, thicker superhydrophobic coatings must be deposited on the surface, where the coating resistance is comparable to the bulk water/ice conduction resistance.
On the existence of optical vortex solitons propagating in saturable nonlinear media
Authors: Medina Luciano
Published: January 2017

In this paper, an existence theory is established for ring-profiled optical vortex solitons. We consider such solitons in the context of an electromagnetic light wave propagating in a self-focusing nonlinear media and governed by a nonlinear Schrödinger type equation. A variational principle and constrained minimization approach is used to prove the existence of positive solutions for an undetermined wave propagation constant. We provide a series of explicit estimates related to the wave propagation constant, a prescribed energy flux, and vortex winding number. Further, on a Nehari manifold, the existence of positive solutions for a wide range of parameter values is proved. We also provide numerical analysis to illustrate the behavior of the soliton’s amplitude and wave propagation constant with respect to a prescribed energy flux and vortex winding number.
Magnetism in pristine and chemically reduced graphene oxide
Authors: Diamantopoulou Α. , Glenis S. , Zolnierkiwicz G. , Guskos N. , Likodimos V.
Published: January 2017

The evolution of magnetism for graphene oxide (GO) before and after chemical reduction was investigated by means of static magnetization and electron spin resonance (ESR) spectroscopy. Strong paramagnetism with a saturation magnetization of ∼1.2 emu/g and weak antiferromagnetic interactions were identified in pristine GO. Apart from spin-half defect centers, ESR spectroscopy indicated the excitation of high spin states, consistently with the high spin (S = 2) magnetic moments derived from the magnetization analysis, corroborating the formation of spatially “isolated” magnetic clusters in GO. A marked reduction of GO's magnetization (∼0.17 emu/g) along with an appreciable rise of diamagnetism (−2.4 × 10−6 emu/g Oe) was detected after chemical reduction by sodium borohydride, reflecting the drastic removal of paramagnetic defects and the concomitant growth of sp2 domains in reduced graphene oxide (rGO). ESR revealed a large drop of the spin susceptibility for rGO, which, in addition to the main paramagnetic Curie component, showed an appreciable Pauli contribution. The latter together with the g-factor shift and the broadening of the ESR line indicated the coupling of localized spins with conduction electrons. The rGO ESR signal presented a metallic line shape, which could be analyzed in terms of two separate spectral components, a broad one that may be related to defect states strongly coupled with itinerant spins within the sp2 clusters and a narrow one due to edge/vacancy defect spins, indicative of rGO's persistent structural inhomogeneity.
A time-dependent model of pulse-driven radio frequency capacitively coupled collisional plasma sheath
Authors: Rahman M. T. , Hossain M. Mofazzal
Published: January 2017

The time-dependent model of ion motion is used to propose an analytical model for dual frequency (DF) capacitively coupled plasma (CCP) sheath driven by a pulsed source and a radio-frequency source. In this model, the sheath is considered to be collisional. In this model, the time dependent terms of ion fluid equations are ignored, but the electric field, ion motion and ion density remain time dependent. Electron profile is assumed to be step-like. Analytical expressions for electron sheath width and sheath potential have been developed. The calculated sheath width and potential are compared with the dual radio frequency driven time dependent models of capacitively coupled plasma sheath. From the temporal evaluation of sheath motion and potential, it has been found that pulse driven sheath has higher sheath potential and sheath width than that of conventional radio frequency driven DF CCP. Moreover, it is also found that ion energy spread can be reduced using pulsed power. From the temporal investigation of sheath motion and potential, it has been found that the duty cycle of the pulse power significantly affects sheath width and sheath potential.
Determination of geometric and electronic structures of organic crystals from first principles: Role of the molecular configuration on the electronic structure
Authors: Yanagisawa Susumu , Hamada Ikutaro
Published: January 2017

We present a van der Waals density functional and many-body perturbation theory based study for accurate prediction of geometric and electronic structures of organic crystals. In addition to the determination of the crystal geometry and the quasiparticle energy, we demonstrate the role of the molecular configuration in organic crystals, which affects the transfer integrals between the frontier orbitals and the dynamical screening effect upon the injected charge. The result highlights the importance of obtaining accurate crystal geometry to elucidate the nature of the electronic state.
Temperature dependent forward current-voltage characteristics of Ni/Au Schottky contacts on AlGaN/GaN heterostructures described by a two diodes model
Authors: Greco Giuseppe , Giannazzo Filippo , Roccaforte Fabrizio
Published: January 2017

This paper reports on the temperature dependence of Ni/Au Schottky contacts on AlGaN/GaN heterostructures. The electrical properties of the Schottky barrier were monitored by means of forward current-voltage (I–V) measurements, while capacitance-voltage measurements were used to determine the properties of the two dimensional electron gas. The forward I–V characteristics of Schottky diodes revealed a strong deviation from the ideal behavior, which could not be explained by a standard thermionic emission model. Thus, the Ni/AlGaN/GaN system has been described by a “two diode model,” considering the presence of a second barrier height at the AlGaN/GaN heterojunction. Following this approach, the anomalous I–V curves could be explained and the value of the flat-band barrier height (at zero-electric field) could be correctly determined, thus resulting in good agreement with literature data based on photoemission measurements.
Magnetic glass-film based on single-nanosize 𝜺 -Fe2O3 nanoparticles
Authors: Yoshikiyo Marie , Namai Asuka , Nakagawa Kosuke , Ohkoshi Shin-ichi
Published: January 2017

We report a magnetic thin film of single-nanosize ε-Fe2O3 in SiO2 matrix. The glass-film was prepared by sintering a silica coated iron oxide hydroxide on a quartz substrate in air. The glass-film consists of ε-Fe2O3 of 8.8 nm size, and its thickness was 570 nm (0.57 μm) with a roughness of 10 nm (0.01 μm). UV-vis spectrum showed that the glass-film has small absorbance of 0.043 at 500 nm. The magneto-optical effect was investigated, and Faraday ellipticity showed a magnetic hysteresis loop with a coercive field of 3.0 ± 0.2 kOe. Furthermore, single-nanosize ε-Fe2O3 without silica was prepared as a reference sample, and ferroelectricity was observed. Therefore, the present thin glass-film consists of single-nanosize ferroelectric-ferromagnetic nanoparticles.
Modulation of light localization in the iridophores of the deep-sea highlight hatchetfish Sternoptyx pseudobscura under magnetic field
Authors: Iwasaka M. , Ohtsuka S.
Published: January 2017

Efficient light control by certain tissue in bioluminescent fish offers potential for new optical devices. In the world’s deep-seas, there are numerous fish species with such bioluminescence yet to be discovered. One such species, the deep-sea highlight hatchetfish Sternoptyx pseudobscura, which was found at depths of ca. 800–900 m in the neighboring waters off the Amami Islands, Japan, exhibits a new form of light-reflection produced in guanine crystal platelets present in the skin Strongly reflecting platelets in the dorsal and anterior-ventral region enhance its reflection in the presence of magnetic fields either in parallel or perpendicular to the incident light. A diamagnetic ordering of the platelet alignment is suggested in producing a small angular rotation of the platelets when placed in a magnetic field. The synchronized ordering of these platelets in parallel possibly modulates the localization of light in a multilayer structure inside the iridophore. The developed method should be useful for investigating the bio-ethological meaning of guanine crystal platelet arrangements in the deep sea fish reflecting light.
Effect of B-doping on the structure and magnetocaloric properties of plate-shaped La0.6Pr0.4Fe11.4Si1.6Hx sintered in high-pressure H2 atmosphere
Authors: Sun Naikun , Ren Zengxin , Guo Jie , Si Pingzhan , Sun Mingze
Published: January 2017

Plate-shaped La0.6Pr0.4Fe11.4Si1.6B0.2Hx bulk samples have been achieved with sintering in a high-purity H2 atmosphere at 50 MPa. The effect of B-doping on the structure, magnetism and magnetocaloric properties of the plate-shaped hydrides has been systematically explored. The results show that B-doping unfavorably leads to a remarkable increase of Fe2B during the sintering process and has not helped much in the 1:13 phase stabilization and/or in the magnetocaloric properties. At 340 K, a high-density sintered thin plate shows a large magnetic-entropy change ΔSm of 16.2 J/kg·K and a favorable small hysteresis of 0.6 J/kg for a field change from 0 to 5 T. High-resolution X-ray microtomography analysis shows that micropores exist in the thin plates causing a porosity of 0.26% and leading to a remarkable reduction of the hysteresis. This work opens an effective route for synthesizing thin magnetic refrigerants of La(Fe, Si)13Hx hydrides.
Comparison of one-way and two-way coupled analyses of electromagnetic machines considering magnetic and structural interactions
Authors: Nam Jahyun , Kang Chiho , Song Jeongyong , Jang Gunhee
Published: January 2017

We compared one-way and two-way coupled analyses of electromagnetic machines considering magnetic and structural interaction to identify the frequency components of magnetic excitation and to determine the structural coupling effects predicted only by the two-way coupled analysis. We developed finite element models of a C-core switch and an electric motor. In the two-way coupled analysis method, the magnetic force calculated by using the Maxwell stress tensor was applied to the structural finite element model to determine the elastic deformation, and the magnetic finite element model was rearranged by means of the moving mesh method to represent the structural elastic deformation. We showed that two-way coupled analysis predicted the excitation frequency of 80 Hz (4 times the input current frequency) of magnetic force in the C-core switch and the excitation frequency of 667 Hz (the first natural frequency of the rotor, corresponding to the translational mode) of magnetic force in the electric motor undergoing rotor eccentricity. We showed that two-way coupled analysis predicted magnetic excitation and its corresponding structural response more accurately than the one-way coupled analysis, especially for electromagnetic machines in which the structural deformation affects magnetic field through variation of the air gap length.
A workflow to build a model investigating coal cleat upscaling conditioned by the lithotype
Authors: Barbosa Karina , Esterle Joan , Ruest Marc
Published: January 2017

Cleats are natural macroscopic fractures in coalbeds. The distribution of cleats inside network patterns is an important attribute as it influences mechanical behaviour, effective permeability and gas production performance. Various publications on geological and geotechnical investigations show relationships between rank class, lithotype and cleat frequency, and it is well known that the block size of coalbeds affect coal strength. These attributes are commonly tested for and numerically modelled independently without regard for any natural sequence (e.g. dulling upward, brightening upward, randomly distributed) within the coalbed.
This paper presents a developing workflow with a methodology to set up a numerical modelling using the coal lithotype information as its basis. The contribution of each lithotype to the whole behaviour of the coalbed under transient stress conditions, and then to the larger rock mass, is considered a critical component. The main issues observed include:

reliable information exists for individual bright bands but not for mixed lithotypes;
neither a correlation between the individual bands and the lithotypes, nor between the lithotype and the coal seam, have been proposed;
derived geotechnical properties are not assumed to be conditioned by the individual lithotypes; and,
upscaling coal geotechnical properties from laboratory tests remains uncertain.

These matters, therefore, should be pursued to allow some quantification of the heterogeneous nature of coal and to capture the combined effects on coalbed strength. It is anticipated that the workflow still requires validation by running a set of numerical experiments for proposed scenarios.
Process safety common lead metrics: implementing and learning
Authors: Fogarty Steve
Published: January 2017

No matter which major accident event investigation is looked into, some common themes concerning the requirements for process safety metrics present themselves. For example, the recent Macondo investigation by the US Chemical Safety Board (CSB) examined both API 754 and IOGP 456, and re-iterated that metrics need to be developed to capture the health of barriers and management systems. The effectiveness of barriers and management systems needs to be assessed, as does the frequency that these barriers are being called upon to make sure that the risk is being properly managed.
Both API 754 and IOGP 456 use the four-tier system, where the top two tiers are lagging, and tiers three and four are more leading. Both standards focus on reporting and benchmarking the lagging metrics; however, the selection of leading metrics is left to be determined by individual companies.
Recent work completed by the IChemE Safety Centre (ISC) focuses on these leading metrics, but takes a different approach by developing a suite of 21 common lead metrics that allows for developments to occur. By having common metrics across companies and across industries, ISC and its member companies are at the groundbreaking point where benchmarking and identification of best practice can begin. APPEA is leading the charge with a unanimous agreement by the CEOs at the April CEO meeting to implement the common lead metrics across the APPEA companies.
Quadrant Energy is well underway with its journey, and this extended abstract discusses the process being undertaken to commence reporting on all 21 of these process safety common lead metrics.
Similarities and differences in the transcriptional control of expression of the mouse TSLP gene in skin epidermis and intestinal epithelium
Authors: Ganti Krishna Priya , Mukherji Atish , Surjit Milan , Li Mei , Chambon Pierre
Published: January 2017

Significance

Thymic stromal lymphopoietin (TSLP) is a critical immunoregulatory cytokine that plays important physiological functions in epithelial cells in skin and intestinal barriers. However, the molecular mechanisms controlling TSLP expression in vivo are still poorly understood. Using tissue-selective mutagenesis in mice, we have identified the involvement of multiple transcriptional factors, including several nuclear receptors and their cognate agonistic ligands, in the transcriptional regulation of TSLP in epidermal keratinocytes and intestinal epithelial cells. Importantly, this investigation also demonstrates that the retinoid X receptor (RXR) and retinoic acid receptor (RAR) isotypes are not functionally redundant in vivo. Taking our data together, the present study unveils the topological map and the combinatorial mechanisms involved in tissue-specific transcriptional regulation of TSLP expression in epidermal keratinocytes and intestinal epithelial cells.
Differential control of retrovirus silencing in embryonic cells by proteasomal regulation of the ZFP809 retroviral repressor
Authors: Wang Cheng , Goff Stephen P.
Published: January 2017

Significance

A key transcriptional silencer responsible for suppression of retroviral gene expression in embryonic stem cells is found to be regulated itself at the level of protein turnover, mediated by ubiquitinylation and proteasomal degradation. The implication is that the stem cell state is characterized not only by an unusual transcriptional profile but also by unusual posttranscriptional regulation.
Glucagon receptor inhibition normalizes blood glucose in severe insulin-resistant mice
Authors: Okamoto Haruka , Cavino Katie , Na Erqian , Krumm Elizabeth , Kim Sun Y. , Cheng Xiping , Murphy Andrew J. , Yancopoulos George D. , Gromada Jesper
Published: January 2017

Significance

Insulin and glucagon are key hormones controlling blood glucose levels. Insulin binding to its receptor promotes glucose disposal in peripheral tissues and suppresses hepatic glucose output. Patients with inactivating mutations in their insulin receptors experience severe insulin resistance and uncontrolled diabetes. No effective therapy is available. Here we demonstrate that glucagon receptor (GCGR) blockade with monoclonal antibody normalized blood glucose in a mouse model of extreme insulin resistance and hyperglycemia. A surprising finding was that compensatory expansions of α- and β-cell masses in settings of inhibited glucagon and insulin signaling occurred at normal glucose levels. The data show that GCGR antibody inhibition represents a potential therapeutic option for patients with extreme insulin-resistance syndromes.
Structural insights into the functional cycle of the ATPase module of the 26S proteasome
Authors: Wehmer Marc , Rudack Till , Beck Florian , Aufderheide Antje , Pfeifer Günter , Plitzko Jürgen M. , Förster Friedrich , Schulten Klaus , Baumeister Wolfgang , Sakata Eri
Published: January 2017

Significance

The 26S proteasome is a large multisubunit complex that executes the degradation of intracellular proteins marked for destruction by ubiquitylation. To understand the mechanistic details of the functional cycle of the 26S proteasome, it is necessary to elucidate the structural features of its “engine,” the AAA
+
ATPase module, which unfolds and translocates substrates into the 20S core particle, where proteolysis takes place. Here, we report cryo-electron microscopy reconstructions of the yeast 26S proteasome in the presence of different nucleotides and nucleotide analogs. Our results provide structural insights into the mechanism of substrate unfolding and translocation by the 26S proteasome.
Concept structuring in Persian PP-centric complex predicates
Authors: Moezzipour Farhad , Ghandhari Mina
Published: January 2017

Prepositions contribute to the schematic meanings in Persian complex predicates. Based on the Concept Structuring System (Talmy 2000), we argue that since the light verb and preverbal noun belong to different subsystems, they fulfill distinctive conceptual dimensions of the semantic representation. The preverbal noun, belonging to the open class system provides the content meaning, while the light verb, belonging to the closed class system, determines the schematic meanings of complex predicates. Analyzing some Persian data, we see (a) how the light verb and preposition are so well connected to each other and to the noun by their configuration (b) how they provide different schematic meanings for different complex predicates and (c) how the same noun can combine with a different light verb and a preposition to elicit a different meaning for the complex predicate.
Hot corrosion and mechanical properties of nanostructured Al2O3/CSZ composite TBCs
Authors: Keyvani A. , Bahamirian M.
Published: January 2017

The purpose of this research is to improve the quality and efficiency of yttria-stabilised zirconia (YSZ) thermal barrier coating (TBC) through replacing CSZ. Three types of top coats including conventional YSZ, CSZ and nanostructured Al2O3/CSZ composite were applied, by thermal spray technique, on IN738LC base metal and the results were compared to one another. In the present investigation, hot corrosion behaviours of the coatings were tested in a furnace containing a mixed environment of Na2SO4 and V2O5 salts at 1050°C. Nanoindentation tests were used to evaluate mechanical properties of the coatings. The experimental results confirmed that nanostructured Al2O3/CSZ composite coating had much hot corrosion resistance than those of conventional TBCs. The transformation of tetragonal zirconia to monoclinic ZrO2 and formation of YVO4 and CeVO4 crystals as hot corrosion products led to the degradation of the mentioned TBCs. Microstructural analysis indicated that the penetration of molten salt was much less in the nanostructured Al2O3/CSZ composite coating where the infiltration of both oxygen and aggressive molten salt was reduced. Mechanical results showed that the superior mechanical properties of nanostructured Al2O3/CSZ composite coating may be attributed to its structural stability.
Effects of plasma treatment, La content and temperature on the La–Ni–Mo–B catalysts for hydrogen production from NaBH4 hydrolysis
Authors: Şahin Ömer , Ekinci Arzu , Balbay Asım , Saka Cafer
Published: January 2017

La–Ni–Mo–B catalysts with 0.15, 0.21 and 0.30-mol La molar ratio are prepared by a mixing method followed by a plasma treatment, characterised and investigated for hydrogen production via sodium borohydride hydrolysis. XRD, SEM, Brunauer–Emmett–Teller and FTIR techniques are used for characterising the catalysts. The hydrogen generation rate at 60°C compared to 30°C using La–Ni–Mo–B under the same conditions is significantly different. The effect of temperature, plasma application time and different plasma gases on hydrogen generation from NaBH4 hydrolysis reaction using La0.21–Ni–Mo–B catalyst is investigated. It was found that the plasma-treated catalysts exhibited low activation energy for zero order (58 kJ mol−1).
Coatings to increase the corrosion behaviour of aluminium foam
Authors: Rossi S. , Fedel M. , Da Col L. , Deflorian F. , Petrolli S.
Published: January 2017

The aluminium foams present very interesting properties due to their low density. However, the presence of cells and the complex geometry are critical aspects considering the corrosion behaviour. A suitable method to increase the corrosion resistance is desirable. The cataphoretic deposited paint could be a useful way due to the possibility to obtain a protective and homogenous paint layer also with complex geometry. Other solution could be the application of an enamel layer, which shows high protection properties together with a good resistance at high temperature. The aim of this paper is the evaluation of the protection performance of these kinds of coatings. The corrosion behaviour of coated samples is evaluated by acetic acid salt spray exposure test and by electrochemical measurements. Both layers, organic coating and enamel, show a high increase of corrosion behaviour in comparison of uncoated aluminium foam.
Morphological characterisation and microstructure of silver films prepared by electrodeposition method
Authors: Nasehnejad M. , Nabiyouni G. , Shahraki M. G.
Published: January 2017

The electrodeposition method is used to prepare silver films at different thickness. In order to characterise the films, scaling law analysis was done using concept of fractal. We obtained a growth exponent, β = 0.61 and average roughness exponent, α = 0.62 using root mean square roughness and height–height correlation function. The results indicate that the films with higher thickness have higher surface roughness. However the fractal analysis using height–height correlation shows that the value of fractal dimension decreases from 2.45 to 2.33 depending on the thickness of films. On the other hand the increase of thickness influenced the lateral correlation length strongly. Thus, these features may be controlled by choosing an optimum film thickness.
Metallisation of polycarbonates using a low pressure cold spray method
Authors: Małachowska Aleksandra , Winnicki Marcin , Stachowicz Mateusz , Korzeniowski Marcin
Published: January 2017

In many industries, polymers are in great demand due to their low weight and good mechanical properties. However, films and coatings are sometimes applied to improve polymer surface properties. This work presents a study on the metallisation of polycarbonates using a low pressure cold spray (LPCS) method. Two types of commercial powders were selected for the deposition of coatings: (i) tin and (ii) aluminium. The coatings were applied (i) on an unmodified substrate and (ii) on a substrate with an interlayer, which enabled the formation of good adherent aluminium coatings. A light and scanning microscopy was used to analyse the microstructure of coatings. Electrical conductivity was determined using the four-probe method and is discussed in relation to the oxygen content. Moreover, bond strength and microhardness were investigated.
Want to promote tissue growth? There’s an App for that!
Authors: Short Ben
Published: January 2017

Study describes how a palmitoyltransferase regulates the Hippo pathway in flies.
The diagnostic accuracy of smartphones in the radiographic analysis of ankle fractures
Authors: Curatolo Evan , Reuter Matthew J. , Howard Roland , Willis Alexander R. , Ahmede Jamil M. , Kwak Andrew , Absatz Michael G.
Published: January 2017

Background:

Orthopaedic surgeons rely on radiographs to assist in the evaluation and treatment of patients. The technological advances of smartphones have allowed data to be transferred quickly and viewed from remote locations. The diagnostic accuracy of viewing radiographs on smartphones remains unproven. As such, this study aimed to evaluate the ability of smartphones to allow surgeons to correctly diagnose and interpret radiographs of ankle fractures on one of the most popular smartphones, an Apple iPhone 4S (Apple Inc, Cupertino, CA, USA).

Methods:

Using the smartphone, individual pictures were taken of anteroposterior, mortise, and lateral radiographs of 20 ankle fractures. These images were then evaluated through 10 questions that included acceptable quality, presence and displacement of fibula, medial malleolus, and posterior malleolar fractures, ankle subluxation, syndesmotic disruption, Lauge-Hansen classification, and the need for open reduction and internal fixation. Results were compared to the same radiographs viewed on a picture archiving and communication system (PACS) workstation.

Results:

Ten orthopaedic surgery residents and five orthopaedic surgery attendings evaluated the radiographs and answered a total of 6000 questions. When comparing the responses between those images viewed on the smartphone versus those viewed on the PACS workstation, 826 differences were found. After analysis of both interobserver and intraobserver reliability, a significant difference was found between viewing modalities, with the smartphone found to be not as reliable as the PACS workstation. However, when looking at the single question of whether or not the fracture would require operative fixation, no significant difference was found between the use of a smartphone or PACS workstation.

Conclusions:

The smartphone images demonstrated a reliable prediction of the proper treatment for the 20 ankle fractures despite noted differences between the two viewing modalities.
Arthroscopic management of small osteochondral lesions of the talus: drilling revisited
Authors: Abd-Ella Mohamed Mokhtar , Elshabrawy Waleed , Fayyad Tamer , Elzahlawy Hany , Abdeldayem Sherif Mostafa , Abdel Rahman Amr F. , Fahmy Hesham
Published: January 2017

Background:

The aim of the study was to evaluate the short-term clinical outcomes of arthroscopic drilling in the management of small osteochondral lesions of the talus (OLT).

Methods:

Thirty-two patients with small OLT (area <150 mm2 and cyst depth <7 mm as measured on CT and MRI) were treated by arthroscopic debridement and drilling. Four patients underwent simultaneous modified Broström procedures. Five patients required retrograde drilling, three because the overlying cartilage was intact and two because the lesion was posterior. Outcomes were measured using the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Scale and subjective patient satisfaction.

Results:

The mean age at surgery was 32±8 yr (range, 18-50 yr). There were 22 men (68.75%) and 10 women (31.25%). Four patients (12.5%) were playing sports regularly, one professionally and three recreationally. After a mean follow-up duration of 26 mo (range 12-48 mo), the mean AOFAS score improved from 71.78±11 (range 51-87) preoperatively to 91±7 (range 80-100). The results were excellent in 15 patients (46.9%), good in 12 (37.5%), fair in five(15.6%). According to the Saxena criteria 16 patients (50%) were very satisfied, nine patients (28.1%) were satisfied, six patients (18.8%) were satisfied with reservations and one patient (3.1%) was unsatisfied.

Conclusions:

Arthroscopic drilling for small OLT is safe and easy with results comparable to microfracture but with the advantages of deeper penetration and the ability to drill retrograde into posterior lesions or lesions with intact cartilage.
Combat-related pelvic ring fractures in survivors
Authors: Purcell Richard L. , McQuade Maximilian G. , Kluk Matthew W. , Gordon Wade T. , Lewandowski Louis R.
Published: January 2017

Background:

Pelvic fractures have been associated with rates of mortality up to 20%, with open injuries approaching rates up to 50%. This study compares differences in patients with open and closed pelvic ring injuries sustained during combat.

Methods:

Retrospective review of 114 patients who sustained a pelvic ring fracture and were alive upon presentation to the United States. We collected demographics, associated injuries, transfusion requirements, and outcomes to include residual bowel or bladder dysfunction and ambulatory status.

Results:

There were 114 patients, 98% male, with 75 closed and 39 open injuries. Average age was 26.6 yr. An average of 8.1 and 28.1 units of red blood cells were transfused in closed and open injuries, respectively (P<0.0001). Bilateral lower extremity amputations occurred in 11% of closed and 59% of open injuries (P<0.0001). Unstable fracture patterns occurred in 39% of closed fractures compared to 51% in open fractures (P=0.233). The time to weight bearing was 93 and 126 days for closed and open injuries (P=0.039). At latest follow-up, abnormal bladder and bowel function both occurred in 10% of closed and, respectively, 39% and 33% of open injuries (P=0.006). The rate of ambulation was 94% for closed injuries and 89% for open injuries (P=0.439).

Conclusions:

In the largest report of combat-related pelvic fractures in surviving patients, the incidence of open fractures was 34%. Although there are significant differences in associated injuries, transfusion requirements and time to weight bearing, patients with open pelvic fractures are able to return to a similar level of ambulatory function as those with closed fractures.
Protecting the trunnion during isolated acetabular component revision total hip arthroplasty: a technical note
Authors: Shemesh Shai , Velkes Steven , Kosashvili Yona , Cohen Nir
Published: January 2017

Corrosion at the trunnion-taper junction of the femoral component in total hip arthroplasty has been identified as a potential concern. Failure of the trunnion-taper junction can be initiated by surface micromotions caused by surface contamination. This technique is to be used in cases of isolated acetabular component revision total hip surgeries. Since the prosthetic head is removed during revision of the acetabular component to optimize exposure, the trunnion remains exposed in the surgical field and, therefore, is subjected to scratching and intimate contact with surgical instruments and accumulation of biologic debris. Use of a plastic sleeve protects the trunnion against intraoperative scratching and contamination.
Optimizing the treatment of osteomyelitis with antimicrobial drugs: current concepts
Authors: Oliveira Priscila Rosalba , Carvalho Vladimir Cordeiro , Lima Ana Lucia Munhoz
Published: January 2017

The success of osteomyelitis treatment, particularly in cases related to implants, depends on extensive surgical debridement and adequate and effective antibiotic therapy. Direct administration of antimicrobial agents through their incorporation into orthopaedic cement is an important adjuvant therapy. The capacity for biofilm to form by causative agents of osteomyelitis is an obstacle to antimicrobial treatment of these infections. Bacteria present in biofilm usually has greater bacterial resistance and higher expression of virulence factors than sessile bacteria, as well as mechanisms to escape the host immune response. The ability of causative agents of infection, particularly Staphylococcus aureus, to form small colony variants (SCV), a phenotype capable of invading and infecting osteoblasts, is another important mechanism that contributes to exacerbation of osteomyelitis to a chronic state. To optimize the antimicrobial treatment of osteomyelitis and improve patients’ prognosis, it is fundamental to consider these complicating factors, as well as the antimicrobial susceptibility profile of the causative microorganisms. Rifampicin should always be considered as part of the therapeutic regimen because it presents good bone concentration and has proven capacity to act on strains present in biofilm and in SCV.
From mechanism to therapies in systemic lupus erythematosus
Authors: Paley Michael A. , Strand Vibeke , Kim Alfred H.J.
Published: January 2017

Purpose of review

Systemic lupus erythematosus (SLE) is a disabling and deadly disease. Development of novel therapies for SLE has historically been limited by incomplete understanding of immune dysregulation. Recent advances in lupus pathogenesis, however, have led to the adoption or development of new therapeutics, including the first Food and Drug Administration–approved drug in 50 years.

Recent findings

Multiple cytokines (interferon, B lymphocyte stimulator, IL-6, and IL-17), signaling pathways (Bruton's Tyrosine Kinase, Janus kinase/signal transducer and activator of transcription), and immune cells are dysregulated in SLE. In this review, we cover seminal discoveries that demonstrate how this dysregulation is integral to SLE pathogenesis and the novel therapeutics currently under development or in clinical trials. In addition, early work suggests metabolic derangements are another target for disease modification. Finally, molecular profiling has led to improved patient stratification in the heterogeneous SLE population, which may improve clinical trial outcomes and therapeutic selection.

Recent advances in the treatment of SLE have directly resulted from improved understanding of this complicated disease. Rheumatologists may have a variety of novel agents and more precise targeting of select lupus populations in the coming years.