bluuebunny/crossref_metadata_2025 huggingface dataset:
Active Control of Fabricating Nanofibrous Wavy/Helical Arrays Using Near-Field Electrospinning
Authors: You Xiangyu , Guo Ping
Published: September 2018

A novel and simple near-field electrospinning (NFES) method has been developed to fabricate wavy or helical nanofibrous arrays. By alternating the electrostatic signals applied on auxiliary-electrodes (AE), the structural parameters of deposited patterns can be actively controlled. Compared with the traditional electrospinning methods based on the bending and buckling effects or collector movement, the proposed method shows advantages in the controllability, accuracy, and minimal feature size. Forces operating on the electrospinning jet and the time-varying electric field distribution were analyzed to explain the kinematics of the jet. Nanoscale wavy and helical patterns with various structural parameters were fabricated. The effects of experimental process parameters on structural parameters of deposited patterns were analyzed to demonstrate the controllability of our method in fabricating wavy or helical nanofibrous structures. It is envisioned that this method will benefit the applications in the field of photovoltaic devices, sensors, transducers, resonators, and stretchable electronics.
Nickel/Alumina Metal Matrix Nanocomposites Obtained by High-Energy Ball Milling and Spark Plasma Sintering
Authors: Martínez-Franco Enrique , Li Ming , Cuenca Álvarez Ricardo , González Hernández Jesús , Ma Chao , Alvarado Orozco Juan Manuel
Published: September 2018

Metal matrix nanocomposites (MMNCs) are anticipated to offer significantly better performance than existing superalloys. Nickel/alumina nanocomposite samples were fabricated with a powder metallurgy method, combining high-energy ball milling (HEBM) and spark plasma sintering (SPS). The objective of this research is to determine the effect of alumina nanoparticle fraction and HEBM parameters on the powder preparation and sintering processes, and resultant microstructure and properties. Nickel-based powders containing various fractions (1, 5 and 15 vol.%) alumina nanoparticles were prepared by HEBM. The initial particle sizes were 44 μm and 50 nm for nickel and alumina, respectively. The milling process was conducted by starting with mixing at 250 rpm for 5 min, followed by cycling operation at high and low speeds (1200 rpm for 4 min and 150 rpm for 1 min). Samples at different milling times (30, 60, 90 and 120 min) of each composition were obtained. Scanning electron microscopy (SEM) was used to evaluate the dispersion of nanoparticles in the powders at different milling times. SPS technique was used for consolidation of the prepared powders. SEM images showed that alumina nanoparticles are homogeneously dispersed in the metal matrix in the sample containing 15 vol.% alumina. Hardness measurements in cross sections of SPSed samples showed higher values for Ni/Al2O3 MMNC compared to pure Ni.
Biomechanical Root Cause Analysis of Complications in Head Immobilization Devices for Pediatric Neurosurgery
Authors: Abdulhafez Moataz , Kadry Karim , Zaazoue Mohamed , Goumnerova Liliana C. , Bedewy Mostafa
Published: September 2018

Precise and firm fixation of the cranium is critical during craniotomy and delicate brain neurosurgery making head immobilization devices (HIDs) a staple instrument in brain neurosurgical operations today. However, despite their popularity, there is no standard procedure for their use and many complications arise from using HIDs in pediatric neurosurgery. In this paper, we identify biomechanical causes of complications and quantify risks in pin-type HIDs including clamping force selection, positioning and age effects. Based on our root cause analysis, we develop a framework to address the biomechanical factors that influence complications and understand the biomechanics of the clamping process. We develop an age-dependent finite element model (FEM) of a single pin on a cranial bone disc with the representative properties and skull thickness depending on age. This model can be utilized to reduce risk of complications by design as well as to provide recommendations for current practices.
Multi-Mode Particle Filter for Bearing Remaining Life Prediction
Authors: Wang Peng , Yan Ruqiang , Gao Robert X.
Published: September 2018

As a critical element in rotating machines, remaining useful life (RUL) prediction of rolling bearings plays an essential role in realizing predictive and preventative machine maintenance in modern manufacturing. The physics of defect (e.g. spall) initiation and propagation describes bearing’s service life as generally divided into three stages: normal operation, defect initiation, and accelerated performance degradation. The transition among the stages are embedded in the variations of monitored data, e.g., vibration. This paper presents a multi-mode particle filter (MMPF) that is aimed to: 1) automatically detect the transition among the three life stages; and 2) accurately characterize bearing performance degradation by integrating physical models with stochastic modeling method. In MMPF, a set of linear and non-linear modes (also called degradation functions) are first defined according to the physical/empirical knowledge as well as statistical analysis of the measured data (e.g. vibration). These modes are subsequently refined during the particle filtering (PF)-based bearing performance tracking process. Each mode corresponds to an individual performance scenario. A finite-state Markov chain switches among these modes, reflecting the transition between the service life stages. Case studies performed on two run-to-failure experiments indicate that the developed technique is effective in tracking the evolution of bearing performance degradation and predicting the remaining useful life of rolling bearings.
Experimental Determination of Thermal Conductivity of Cortical Bone With Heat Loss Estimation
Authors: Lee JuEun , Huh Seon Jeong , Lee Hee Joon
Published: September 2018

This paper presents an experimental measurement of the thermal conductivity of bovine cortical bone by an improved parallel plate method to increase the accuracy of the measurement. An experimental apparatus was designed to measure the thermal conductivity of the cortical bone using a reference material with a known thermal conductivity by the heat transfer through the samples. To improve the measurement accuracy, a reference material was selected as quartz, which is of the same order of magnitude of the thermal conductivity of bovine cortical bone reported in the existing literature. Additionally, the temperatures at the heat source and heat sink were set to ±5°C from the ambient temperature to reduce the inevitable heat loss in the measurement. The temperature offset was determined numerically. The current experimental measurement was validated by an in-house finite-difference numerical program. The heat loss in the measurement was predicted from the numerical program. The thermal conductivity of the bovine cortical bone was then determined to be 0.55 ± 0.02 W/mK with compensating heat loss.
Supercritical CO2 Pretreatment of Cellulosic Biomass for Biofuel Production: Effects of Biomass Particle Size
Authors: Yang Yang , Deines Timothy , Zhang Meng , Zhang Ke , Wang Donghai
Published: September 2018

Biofuel derived from cellulosic biomass is a sustainable alternative to petroleum-based fuel. Pretreatment is an essential step in biofuel production because it accounts for more than 20% of the inputs. Furthermore, particle size reduction as a preprocessing step prior to pretreatment exerts a substantial impact on all following processes. Many studies have investigated the effects of biomass particle size on sugar yield after conventional pretreatments of biomass such as alkaline and dilute acid pretreatments. The similar trends have shown that smaller biomass particle size results in higher sugar yield. Supercritical CO2 (SC-CO2) pretreatment has been applied at 1450 psi, 120 °C for 30 mins in this study as a pretreatment method for biofuel production from cellulosic biomass. As a recyclable green-chemistry method, SC-CO2 pretreatment offers many advantages such as no toxic chemicals added and low-cost input. The objective of this study is to understand the effects of particle size on sugar yield after SC-CO2 pretreatment. Three particle size: 1 mm, 2 mm, and 4 mm were used for size reduction of corn stover. Ethanol and water were used as co-solvents to enhance SC-CO2 pretreatment. Analysis of variance (ANOVA) was performed and it is found that, after SC-CO2 pretreatment, the sugar yields differ significantly between 1 mm and 2 mm, 1 mm and 4 mm. In contrast, there is no significant difference between 2 mm and 4 mm after SC-CO2 pretreatment. 1 mm particle produced the highest sugar yield of 0.115 g glucose per 1 g of dry biomass which is 16.62% and 10.39% higher than the 4 mm and 2 mm corn stover biomass produced.
Synthesis of Porous Noble Metal Films With Tunable Porosity by Timed Dealloying
Authors: Niauzorau Stanislau , Ferreira Placid , Azeredo Bruno
Published: September 2018

Nanoporous metal foams have an increasing importance in applications such as chemical catalysis, energy storage, and nanomedicine. This paper examines a simple strategy for controlling the pore volume fraction and pore size of nanoporous films synthesized by dealloying thin-films. By means of controlling the temperature and concentration of nitric acid in dealloying of AgAu thin-films, partially dealloyed AgAu nanoporous films are produced with a high degree of control over the pore size and pore volume fraction. Such capability enables the design of nanoporous metal catalysts materials with desired morphology.
Experimental Investigation of Charged Particles Emission in Machining: Towards Process Monitoring
Authors: Govindaraj Jagadeesh , Subbiah Sathyan
Published: September 2018

Charged particles are emitted when a material undergoes plastic deformation and failure. In machining, plastic deformation and shearing of work piece material takes place continuously; hence, emission of charged particles can be expected. In this work, an in-situ sensor has been developed to capture the emitted positively (positive ion) and negatively (electron and negative ion) charged particles in real time in an orthogonal machining process at atmospheric conditions without the use of coolant. The sensor consists of a Faraday plate, mounted on the flank face of the cutting tool, to collect the emitted ions and the intensity of emissions is measured with an electrometer. Positively and negatively charged particles are measured separately by providing suitable bias voltage supply to the Faraday plate. Ion emissions are measured during machining of three different work piece materials (mild steel, copper and stainless steel) using a carbide cutting tool. The experimental results show a strong correlation between the emission intensity and variation in machining parameters and material properties. Increasing material removal rate in machining increases the intensity of charged particle emissions because of increase in volume of material undergoing shear, fracture, and deformation. It is found that emission intensity is directly proportional to the resistivity and strength of workpiece material. Charged particles emission intensity is found to be very sensitive to the machining conditions which enables the use of this sensor as an alternate method of tool condition monitoring.
A Two-Layer Long Short-Term Memory Network for Bottleneck Prediction in Multi-Job Manufacturing Systems
Authors: Lai Xingjian , Shui Huanyi , Ni Jun
Published: September 2018

Throughput bottlenecks define and constrain the productivity of a production line. Prediction of future bottlenecks provides a great support for decision-making on the factory floor, which can help to foresee and formulate appropriate actions before production to improve the system throughput in a cost-effective manner. Bottleneck prediction remains a challenging task in literature. The difficulty lies in the complex dynamics of manufacturing systems. There are multiple factors collaboratively affecting bottleneck conditions, such as machine performance, machine degradation, line structure, operator skill level, and product release schedules. These factors impact on one another in a nonlinear manner and exhibit long-term temporal dependencies. State-of-the-art research utilizes various assumptions to simplify the modeling by reducing the input dimensionality. As a result, those models cannot accurately reflect complex dynamics of the bottleneck in a manufacturing system. To tackle this problem, this paper will propose a systematic framework to design a two-layer Long Short-Term Memory (LSTM) network tailored to the dynamic bottleneck prediction problem in multi-job manufacturing systems. This neural network based approach takes advantage of historical high dimensional factory floor data to predict system bottlenecks dynamically considering the future production planning inputs. The model is demonstrated with data from an automotive underbody assembly line. The result shows that the proposed method can achieve higher prediction accuracy compared with current state-of-the-art approaches.
Additively Manufactured Full-Density Stainless Steel 316L With Binder Jet Printing
Authors: Do Truong , Bauder Tyler J. , Suen Hawke , Rego Kristian , Yeom Junghoon , Kwon Patrick
Published: September 2018

Binder jet printing (BJP), one of the early metal 3D printing technologies, has distinct advantages over the other 3D printing processes that employ locally melting or welding to build 3D parts. Some of the advantages of BJP include printed parts free of residual stresses, build plate not being required, and less powder usage. However, the BJP technology has been adopted only in limited applications such as prototyping and sand molding because of its difficulty in achieving full-density parts. Based on our previous work on stainless steel (SS) 420, the same BJP protocol was used to attain full-density parts made of SS 316L. The effect of the particle size, mixture ratio, and sintering additives on the densities of printed and sintered parts is investigated for SS 316L powder. Three distinct sizes of SS 316L powders are mixed to improve the packing density. A systematic study of the binder burn-out procedure is conducted using thermogravimetric analysis, leading to a complete removal of binder phase without oxidizing SS 316L powder. The optimal sintering condition for some powder mixtures is determined to obtain the maximum density with the addition of small amounts of boron compounds as sintering additives. The quality of the fully-sintered SS 316L parts is evaluated using the various measurements including density, microstructure, hardness, and surface roughness. As we did with SS 420, the relative density of 99.6% is obtained for SS 316L without structural distortion. This is the first demonstration of such density for SS 316L using the BJP technology without any infiltration.
Friction Sintering of Copper Powder Using a New Rapid, Cost Effective and Energy Efficient Process
Authors: Sharma Vyas Mani , Maity Debanjan , Racherla Vikranth , Pal Surjya Kanta
Published: September 2018

Dendritic electrolytic copper powder was sintered using a newly developed friction sintering process. Green copper pellets of 14 mm height and 16 mm diameter were prepared at room temperature with 5-ton load and 60 seconds holding time. The pellets were sintered using a newly developed rapid, cost-effective, energy efficient, green friction sintering process that allows for easy and quick removal of sintered products. An aluminum plate of 14 mm thickness and 16.1 mm diameter through hole was used to hold green pellets during sintering. Frictional heat and pressure were applied on a top plate through a rotating 18 mm diameter, flat shoulder, WC tool. Sintering was performed at 12 kN axial load and 800 rpm tool rotational speed. Sintering temperatures were measured using K-type thermocouples. SEM (scanning electron microscope) images of fractured surfaces for sintered pellets show neck formation between copper particles. The neck formation is approximately uniform throughout the depth. This is in-line with hardness results along the thickness of the pellet. The process holds promise particularly for solid-state sintering of metal based powders.
Mask-Based Microsphere Photolithography
Authors: Qu Chuang , Kinzel Edward C.
Published: September 2018

Microsphere Photolithography (MPL) uses a self-assembled array of transparent microspheres to focus incident ultraviolet radiation and produce an array of photonic jets in photoresist. Typically, the microspheres are self-assembled directly on the photoresist layer and are removed after exposure during development. Reusing the microsphere array reduces the expense of the process. A mask is formed by transferring the self-assembled microsphere array to a transparent tape. This can be used for multiple exposures when pressed into contact with the photoresist. This paper demonstrates the use of this process to pattern infrared metasurface absorbers and discusses the effects of the mask-based MPL process on the metasurface performance.
Microstructure and Tensile Properties of SLM Graphene Reinforced Inconel 718 Alloy After Post Heat Treatment
Authors: Wang Yachao , Shi Jing
Published: September 2018

Graphene is an ideal reinforcement material for metal matrix composites (MMC) owing to its high strength, high ductility, light weight, as well as good bonding with metal matrix. Additive manufacturing such as selective laser melting (SLM) brings the advantages of low material waste, high flexibility, and short production lead cycle. In this study, graphene nano-platelets (GNPs) reinforced Inconel 718 composites are fabricated by SLM technique and processed under various post heat treatment schemes. It is found that fabrication of GNPs reinforced MMC using SLM technique is a viable approach. The obtained composite possesses dense microstructure and enhanced tensile strength. Post heat treatments at two levels of solution temperature (980 and 1220°C) for 1 hour followed by two-step aging are carried out. The experiment results indicate that addition of GNPs into Inconel 718 matrix results in significant strength improvement. At as-built condition, the ultimate tensile strengths are 997 and 1447 MPa, respectively at 0 and 4.4vol.% GNP content. Moreover, under as-built and solution treated condition, high content of GNPs results in overall higher UTS value and the strengthening effect is most significant at as-built condition. Meanwhile, γ′ and γ″ precipitation hardening is suppressed in the GNPs reinforced composite under aged condition due to the formation of MC carbide and depletion of Nb. Incorporating GNPs in Inconel 718 effectively inhibits the grain growth during post heat treatment.
Fast Computation of Thermal Field of Direct Metal Deposition: A Preliminary Study Based on Quiet Element Method
Authors: Wang Jin , Shi Jing , Wang Yi , Hu Yuli , Dai Jun , Xu Kewei
Published: September 2018

Direct metal deposition (DMD) is a major additive manufacturing (AM) process, which employs high energy beams as the heat source to melt and deposit metals in layerwise fashion so that complex structural components can be directly obtained. Similar to other metal AM processes, DMD is a complicated thermo-mechanical process, characterized by fast scan rates, large thermal gradients, rapid material phase transformations, and cyclic non-uniform temperature changes. Accurate and efficient computation of the thermal field during the DMD process is essential for understanding the fundamental microstructure evolution and developing the optimization strategy. In this paper, we aim to develop an open-source and fast computation tool for analyzing the heat transfer during the DMD process, which is based on the finite volume formulation and the quiet element method and allows development of customized functionalities at the source level. A computing tool is developed in MATLAB for fast prediction of the temperature field during metal additive manufacturing, and compared against the regular finite element analysis using a commercial software. The preliminary results show that for a system of 14400 cells, deposition of a single path takes 174 s using the commercial software, and 15.8s to 81s depending on the setting of convergence criterion using the in-house code. This represents a time reduction ranged from 90.9% to 53.4%, and the overall error is around 12.1%.
Viscous Shear Banding in Cutting of Metals
Authors: Sagapuram Dinakar , Viswanathan Koushik
Published: September 2018

Shear banding is a type of plastic flow instability with often adverse implications for cutting and deformation processing of metals. Here, we study the mechanics of plastic flow evolution within single shear bands in two different (Ti and Ni-based) alloy systems. The local shear band displacement profiles are quantitatively mapped at high resolution using a special micro-marker technique. The results show that shear bands, once nucleated, evolve by a universal viscous sliding mechanism that is independent of microstructural details. The evolution of local deformation around the band is accurately captured using a simple momentum diffusion model by assuming Bingham flow rheology for the band material. The predicted band viscosity is very small, comparable to those of liquid metals. A plausible explanation for this small viscosity and fluid-like behavior at the band, based on phonon drag, is presented.
Effects of Compression Force and Heating Power on Bipolar Tissue Welding
Authors: Li Xiaoran , Chen Roland K. , Li Wei
Published: September 2018

Bipolar tissue welding is often performed with a set of laparoscopic forceps in a minimal invasive surgery to achieve less bleeding and shorter recovery time. However, problems such as tissue sticking, thermal damage, and joint failure need to be solved before the process can be reliably used in more surgical procedures. In this study, experiments were conducted to examine the effect of process parameters and dynamic impedance for prediction of the size of denatured tissue zone during welding. A weld lobe that defines suitable process conditions was constructed. It is found that tissue denaturation starts from the center of the heated region. Dynamic impedance is strongly affected by the compression level and heating power. The size of denatured tissue zone can be predicted with the heating energy; however, the prediction is strongly dependent on the compression level.
Optimizing Process Conditions in Friction Stir-Diffusion Lap Welding of Aluminum Alloy With Cold Rolled Steel
Authors: Al-Badour Fadi , Merah Necar , Mohamed Omer , Bazoune Abdelaziz , Shuaib Abdelrahman
Published: September 2018

This paper deals with the development of friction stir diffusion bonding between 2 mm thick 5052 Aluminum alloy and Cold rolled Steel for cladding application. The investigation focuses on the effect of process conditions on tensile-shear strength of produced lap joint by considering four independent welding parameters: tool rotational speed, welding speed, tool axial force and tool offset in the consecutive pass. A short tool-pin was utilized to avoid tool penetration into the steel substrate and mechanical mixing between clad material and the substrate. In order to optimize the process parameters for maximum joint strength and minimize the number of tests, Taguchi orthogonal array L9 with four factors and three levels was used. Results revealed that tool rotational speed had the greatest influence on produced weld strength. On the other hand, the tool pin length or penetration depth was found to have more effect on weld strength than the axial force. Moreover, clamps’ rigidity had a great impact on joint strength. For the selected material and tool, the optimum welding conditions were found to be 1000 rpm rotational speed, 12 kN plunging force, 100 mm/min welding speed and 12 mm tool offset.
Residual Stresses in Bimetallic Weld Joint With Varying Buttering Layer Thickness
Authors: Chhibber Rahul , Arora Navneet , Dutta B. K.
Published: September 2018

The use of bimetallic weld joints is widespread in thermal and nuclear energy generation. It is evident from literature survey that the weld and ferritic steel HAZ region of bimetallic joints are prone to failures. The failures can be attributed to the generation of residual stresses in bimetallic welds. A typical bimetallic weld joint, representing a joint being tested for use in Indian Nuclear Reactors was fabricated between SA 516 Grade 65 and 304 austenitic stainless steel with and without the use of SS 309 L buttering layer. The buttering layer thickness was varied and surface and subsurface residual stresses were assessed using the hole drilling technique and neutron diffraction measurements. It was found that the SS 309 L buttering layer with thickness of around 6 mm employed in the bimetallic weld joint reduces the surface and sub-surface residual stresses in the critical region (ferritic steel HAZ) of the bimetallic weld joint.
Functional Redundancy in the Hydroxycinnamate Catabolism Pathways of the Salt Marsh Bacterium Sagittula stellata E-37
Authors: Frank Ashley M. , Chua Michelle J. , Gulvik Christopher A. , Buchan Alison
Published: September 2018

Hydroxycinnamates (HCAs) are essential components of lignin and are involved in various plant functions, including defense. In nature, microbial degradation of HCAs is influential to global carbon cycling. HCA degradation pathways are also of industrial relevance, as microbial transformation of the HCA, ferulate, can generate vanillin, a valuable flavoring compound. Yet, surprisingly little is known of the genetics underlying bacterial HCA degradation. Here, we make comparisons to previously characterized bacterial HCA degraders and use a genetic approach to characterize genes involved in catabolism and uptake of HCAs in the environmentally relevant marine bacterium
Sagittula stellata
. We provide evidence of overlapping substrate specificity between HCA degradation pathways and uptake proteins. We conclude that
S. stellata
is uniquely poised to utilize HCAs found in the complex mixtures of plant-derived compounds in nature. This strategy may be common among marine bacteria residing in lignin-rich coastal waters and has potential relevance to biotechnology sectors.
Candida albicans Ras1 Inactivation Increases Resistance to Phagosomal Killing by Human Neutrophils
Authors: Salvatori Ornella , Pathirana Ruvini U. , Kay Jason G. , Edgerton Mira
Published: September 2018

Host phagocytic cells are crucial players in initial defense againstCandida albicansinfection.C. albicansutilizes MAP kinases and Ras1 stress response signaling pathways to protect itself from killing by immune cells.
A Subset of Exoribonucleases Serve as Degradative Enzymes for pGpG in c-di-GMP Signaling
Authors: Orr Mona W. , Weiss Cordelia A. , Severin Geoffrey B. , Turdiev Husan , Kim Soo-Kyoung , Turdiev Asan , Liu Kuanqing , Tu Benjamin P. , Waters Christopher M. , Winkler Wade C. , Lee Vincent T.
Published: September 2018

The bacterial bis-(3′-5′)-cyclic dimeric GMP (c-di-GMP) signaling molecule regulates complex processes, such as biofilm formation. c-di-GMP is degraded in two-steps, linearization into pGpG and subsequent cleavage to two GMPs. The 3′-to-5′ exonuclease oligoribonuclease (Orn) serves as the enzyme that degrades pGpG in
Pseudomonas aeruginosa
. Many phyla contain species that utilize c-di-GMP signaling but lack an Orn homolog, and the protein that functions to degrade pGpG remains uncharacterized. Here, systematic screening of genes encoding proteins containing domains found in exoribonucleases revealed a subset of genes encoded within the genomes of
Bacillus anthracis
and
Vibrio cholerae
that degrade pGpG to GMP and are functionally analogous to Orn. Feedback inhibition by pGpG is a conserved process, as strains lacking these genes accumulate c-di-GMP.
Novel Metabolic Pathways and Regulons for Hexuronate Utilization in Proteobacteria
Authors: Bouvier Jason T. , Sernova Natalia V. , Ghasempur Salehe , Rodionova Irina A. , Vetting Matthew W. , Al-Obaidi Nawar F. , Almo Steven C. , Gerlt John A. , Rodionov Dmitry A.
Published: September 2018

Hexuronate catabolic pathways and their transcriptional networks are highly variable among different bacteria. We identified novel transcriptional regulators that control the hexuronate and aldarate utilization genes in four families of proteobacteria. By regulon reconstruction and genome context analysis we identified several novel components of the common hexuronate/aldarate utilization pathways, including novel uptake transporters and catabolic enzymes. Two novel families of lactonases involved in the oxidative pathway of hexuronate catabolism were characterized. Novel transcriptional regulons were validated via
in vitro
binding assays and gene expression studies with
Polaromonas
and
Ralstonia
species. The reconstructed catabolic pathways are interconnected with each other metabolically and coregulated via the GguR regulons in proteobacteria.
Development of a Specific and Sensitive Enzyme-Linked Immunosorbent Assay as an
In Vitro
Diagnostic Tool for Detection of Bartonella henselae Antibodies in Human Serum
Authors: Jost Markus , Latz Andreas , Ballhorn Wibke , Kempf Volkhard A. J.
Published: September 2018

Bartonella henselae
causes cat scratch disease and several other clinical entities. Infections with
B. henselae
are frequently occurring; however, the infection is only rarely diagnosed, mainly due to a lack of knowledge in the medical community.
Phylogenetically Novel Uncultured Microbial Cells Dominate Earth Microbiomes
Authors: Lloyd Karen G. , Steen Andrew D. , Ladau Joshua , Yin Junqi , Crosby Lonnie
Published: September 2018

In the past few decades, it has become apparent that most of the microbial diversity on Earth has never been characterized in laboratory cultures. We show that these unknown microbes, sometimes called “microbial dark matter,” are numerically dominant in all major environments on Earth, with the exception of the human body, where most of the microbes have been cultured. We also estimate that about one-quarter of the population of microbial cells on Earth belong to phyla with no cultured relatives, suggesting that these never-before-studied organisms may be important for ecosystem functions.
Varicella causing remission of Cushing’s disease
Authors: Raj Henith , Kamalanathan Sadishkumar , Sahoo Jaya Prakash , Kadhiravan Tamilarasu
Published: September 2018

An 18-year-old male with Cushing’s disease presented with generalised skin eruptions and backache. He was diagnosed with varicella infection. During the course of the illness, he developed persistent vomiting. Hormonal evaluation suggested adrenal insufficiency. MRI of brain showed features of pituitary apoplexy. Initially, he required hydrocortisone replacement. Later on his hypothalamic–pituitary–adrenal axis recovered and he is currently asymptomatic without any treatment.
On a knife-edge: clinical uncertainty with an extensive knife blade in situ in the craniofacial region
Authors: Dai Dairui , Meyer Silke , Kaltheuner Lars Christian , Plani Frank
Published: September 2018

A 25-year-old man presented to the trauma department following a penetrating stab wound to his left infraorbital margin with retained knife blade causing superoposterior displacement of the globe. Plain skull X-ray revealed an extensive retained blade with subsequent CT imaging revealing the tip of the blade had reached the right styloid process with no neurovascular compromise. Initial concern was primarily for the left eye leading to ophthalmology being the first specialty requested to review the patient. However, once the extent of the injury was established, ophthalmology requested further review from maxillofacial, ENT and neurosurgery. This resulted in an 84 hours wait between the initial injury and the removal of the knife blade. Incredibly, the patient had no initial sequelae from such an extensive injury and had an unremarkable recovery with no further complications aside from a laceration to the left inferior rectus muscle that was conservatively managed.
Skin metastasis: a rare presentation in testicular germ cell tumour
Authors: Vanidassane Ilavarasi , Mittal Abhenil , Kumar Chandan , Tanwar Pranay , Sahoo Ranjit Kumar , Batra Atul
Published: September 2018

A 35-year-old man presented with a history of cough, haemoptysis, weight loss for 2 months along with ulceroproliferative lesions on the chin and the scalp. On evaluation he was found to have non-seminomatous germ cell tumour, stage 3 c, poor risk with Eastern Cooperative Oncology Group Performance Status of 4. The skin lesions were proven to be metastasis by fine-needle aspiration cytology. He showed significant improvement with a 3-day protocol of abbreviated etoposide and cisplatin chemotherapy and is planned for 4 cycles of VIP. This case describes an uncommon presentation of germ cell tumour in the form of skin metastasis with excellent response to chemotherapy.
Nut consumption and incidence of seven cardiovascular diseases
Authors: Larsson Susanna C , Drca Nikola , Björck Martin , Bäck Magnus , Wolk Alicja
Published: September 2018

Background

Nut consumption has been found to be inversely associated with cardiovascular disease mortality, but the association between nut consumption and incidence of specific cardiovascular diseases is unclear. We examined the association between nut consumption and incidence of seven cardiovascular diseases.

Methods

This prospective study included 61 364 Swedish adults who had completed a Food Frequency Questionnaire and were followed up for 17 years through linkage with the Swedish National Patient and Death Registers.

Results

Nut consumption was inversely associated with risk of myocardial infarction, heart failure, atrial fibrillation and abdominal aortic aneurysm in the age-adjusted and sex-adjusted analysis. However, adjustment for multiple risk factors attenuated these associations and only a linear, dose–response, association with atrial fibrillation (ptrend=0.004) and a non-linear association (pnon-linearity=0.003) with heart failure remained. Compared with no consumption of nuts, the multivariable HRs (95% CI) of atrial fibrillation across categories of nut consumption were 0.97 (0.93 to 1.02) for 1–3 times/month, 0.88 (0.79 to 0.99) for 1–2 times/week and 0.82 (0.68 to 0.99) for ≥3 times/week. For heart failure, the corresponding HRs (95% CI) were 0.87 (0.80 to 0.94), 0.80 (0.67 to 0.97) and 0.98 (0.76 to 1.27). Nut consumption was not associated with risk of aortic valve stenosis, ischaemic stroke or intracerebral haemorrhage.

Conclusions

These findings suggest that nut consumption or factors associated with this nutritional behaviour may play a role in reducing the risk of atrial fibrillation and possibly heart failure.

Trial registration number

NCT01127711 and NCT01127698; Results.
Antiplatelet Therapy in Acute Mild-Moderate Ischemic Stroke (ATAMIS): a parallel, randomised, open-label, multicentre, prospective study
Authors: Hou Xiaowen , Li Xiaoqiu , Wang Xinhong , Chen Huisheng
Published: September 2018

Background

A recent study shows that dual antiplatelet therapy with clopidogrel plus aspirin is superior to aspirin monotherapy for minor stroke, which is defined as a National Institutes of Health Stroke Scale (NIHSS)score of ≤3. However, acute mild-moderate ischaemic stroke (4≤NIHSS≤10) still needs aggressive antiplatelet intervention to prevent deterioration and recurrence of stroke. The efficacy and safety of dual antiplatelet therapy versus aspirin monotherapy in the population are not clear. A multicentre clinical trial is designed to evaluate the efficacy and safety of clopidogrel plus aspirin therapy versus aspirin monotherapy within 48 hours of symptom onset of mild-moderate ischaemic stroke.

Methods/Design

The study is a randomised, open-label, multicentre, prospective trial with a target enrolment of 2700 patients from 60 centres in Northeast China. A treatment allocation identification number to each enrolled patient will be provided by a random number generator. The follow-up time for the clopidogrel plus aspirin and aspirin monotherapy groups is 90 days. The primary efficacy endpoint is a stroke progression event, which is defined as ≥4 point increase in the NIHSS score in 48 hours. The second efficacy endpoints include new ischaemic stroke within 90 days, change in the NIHSS score within 14 days, modified Rankin Scale score on day 90 and other vascular or death events within 90 days. The safety endpoints include mucocutaneous haemorrhage, organ haemorrhage and intracranial haemorrhage, adverse events and severe adverse events. χ2test, t-test (or Mann-Whitney test), survival analysis and Cox proportional hazards models will be conducted. The findings of the study may provide an important evidence for clinical practice for these patients.

Discussion

The trial will be conducted under a rational design and will provide valuable evidence on the appropriate treatment for this population.

Ethics and dissemination

The study was reviewed and approved by the Ethics Committee of the General Hospital of Shen-Yang Military Region (no K(2016) 6).

Trial registration number

NCT02869009; Pre-results.
A hybrid computational approach for option pricing
Authors: Zhu Song-Ping , He Xin-Jiang
Published: September 2018

In this paper, we propose a novel numerical approach for option pricing with the combination of the MC (Monte Carlo) simulation and the PDE (partial differential equation) approach. Our motivation originates from the fact that within a finite life time of an option contract, the underlying price as well as the range of volatility are expected to vary within a relatively small region centered around the current value of the underlying and the volatility and hence there is no need to compute option prices for the underlying and the volatility values beyond this region. Thus, our hybrid approach takes the advantage of both the MC simulation and PDE approach to form an approach that takes the MC simulation as a special case with the region being extremely small and the PDE approach as another special case with the region being extremely large. Through numerical experiments, we demonstrate that such a hybrid approach enhances computational efficiency, while maintaining the same level of accuracy when either the MC simulation or the PDE approach is used alone for the option prices computed within a suitably chosen interested region.
Pricing multi-asset American option under Heston stochastic volatility model
Authors: Samimi Oldouz , Mehrdoust Farshid
Published: September 2018

In this paper, we employ the Least-Squares Monte-Carlo (LSM) algorithm regarding three discretization schemes, namely, the Euler–Maruyama discretization scheme, the Milstein scheme and the Quadratic Exponential (QE) scheme to price the multiple assets American put option under the Heston stochastic volatility model. Some numerical results are presented to demonstrate the effectiveness of the proposed methods.
Pore space characteristics of the Upper Visean ‘Rudov Beds’: insights from broad ion beam scanning electron microscopy and organic geochemical investigations
Authors: Misch D. , Klaver J. , Gross D. , Rustamov J. , Sachsenhofer R. F. , Schmatz J. , Urai J. L.
Published: September 2018

This study gives valuable insights into the microstructure and pore space characteristics of 17 compositionally variable Visean shale samples from the Ukrainian Dniepr-Donets Basin (the ‘Rudov Beds’). The representative imaging area varies considerably (from 10 000 to >300 000 µm
2
) as a function of the mineralogy and diagenetic overprinting. The pores hosted in organic matter (OM) are restricted to secondary solid bitumen. Based on high-resolution maps from broad ion beam scanning electron microscopy combined with organic geochemical and bulk mineralogical data, we propose that the amount of OM-hosted porosity responds to the availability of pore space, enabling the accumulation of an early oil phase, which is then progressively transformed to a porous solid bitumen residue. The type of OM porosity (pendular/interface v. spongy) is reflected in the individual pore size distributions: the spongy pores are usually smaller (<50 nm) than the pendular or OM–mineral interface pores. The OM-hosted porosity coincides with differences in the composition of the extract, with high amounts of extractable OM and saturated/aromatic compound ratios indicative of abundant porous solid bitumen. The average circularity and aspect ratio of the mineral matrix pores correlate with the corresponding values for the OM-hosted pores, which show a preferred bedding-parallel orientation, suggesting that compaction influenced both types of pore.
Vibration Analysis of Thin Plate Structures Subjected to a Moving Force Using Frequency‐Domain Spectral Element Method
Authors: Kim Taehyun , Lee Usik
Published: September 2018

A frequency‐domain spectral element method (SEM) is proposed for the vibration analysis of thin plate structures subjected to a moving point force. The thin plate structures may consist of multiple rectangular thin plates with arbitrary boundary conditions that form multispan thin plate structures, such as bridges. The time‐domain point force moving on a thin rectangular plate with arbitrary trajectory is transformed into a series of stationary point forces in the frequency domain. The vibration responses induced by the moving point force are then obtained by superposing all vibration responses excited by each stationary point force. For the vibration response of a specific stationary point force, the plate subjected to the specific stationary point force is represented by four spectral finite plate elements, which were developed in the authors’ previous work. The SEM‐based vibration analysis technique is first presented for single‐span thin plate structures and then extended to the multispan thin plate structures. The high accuracy and computational efficiency of the proposed SEM‐based vibration analysis technique are verified by comparison with other well‐known solution methods, such as the exact theory, integral transform method, finite element method, and the commercial finite element analysis package ANSYS.
Vibration Characteristics Analysis of Convalescent‐Wheelchair Robots Equipped with Dynamic Absorbers
Authors: Wang Song , Zhao Leilei , Hu Yanzhu , Yang Fuxing
Published: September 2018

To provide a theoretical guidance for the vibration isolation design, the vibration responses characteristics for the convalescent‐wheelchair robot with DA (dynamic absorber) undergoing the random road were revealed. Firstly, the vibration model of the convalescent‐wheelchair system with DA was created. The frequency response functions of the road excitation velocity to the convalescent acceleration, the wheelchair body acceleration, and the tire dynamic deflection were deduced. Then, the numerical calculation method of the PSD (power spectral density) and the RMS (root mean square) responses were proposed. Thirdly, the vibration isolation performances of the wheelchair robot with DA and without DA were compared. Finally, the sensitivity analysis of the vibration responses to the mass ratios, the damping ratios, and the natural frequencies was carried out to reveal the effects of the parameters on the vibration responses. The results show that the DA can partly suppress the vibration of the convalescent and the wheelchair body, especially in the resonance area of the wheelchair body. However, the DA cannot successfully improve the tire contact behavior.
Immobilization of a Laccase/2,2’-azino-bis-(3-ethylbenzothiazoline)-6-sulfonic Acid System to Layered Double Hydroxide/Alginate Biohybrid Beads for Biodegradation of Malachite Green Dye
Authors: Huang Juan , Yang Yun , Wang Yaokun , Zhang Mingyang , Liu Youxun
Published: September 2018

The application of laccase-mediator-based catalysis is limited owing to the high cost of laccases and mediators and the potential toxicity of free mediators. Here, a novel biocatalyst (Im-LMS) was fabricated by immobilizing both laccase and a mediator (2,2’-azino-bis-[3-ethylbenzothiazoline]-6-sulfonic acid) on layered double hydroxide/alginate biohybrid beads. The catalytic activity of Im-LMS was evaluated for dye decolorization using malachite green. The decolorization yields of malachite green by Im-LMS and the free laccase-mediator system were 92% within 120 min and 90% within 90 min. Malachite green solution was detoxified completely after biodegradation by Im-LMS. Following eight reuse cycles of Im-LMS for dye treatment, a decolorization yield of 79% was obtained. The activity of Im-LMS was almost completely stable after being stored for 10 days. The recyclability and stability of Im-LMS will be helpful for reducing the running cost and potential toxicity associated with mediators to facilitate practical applications.
Seroprevalence of Malaria and Hepatitis B Coinfection among Pregnant Women in Tamale Metropolis of Ghana: A Cross-Sectional Study
Authors: Helegbe Gideon Kofi , Aryee Paul Armah , Mohammed Baba Sulemana , Wemakor Anthony , Kolbila David , Abubakari Abdul-Wahid , Askanda Salam , Alhassan Rashid , Barnie Collins , Donkoh Afua Aboagyewaa , Ofosu Ernest
Published: September 2018

Background. Coinfections are becoming common risk factors that may contribute to the increased burden of morbidity in pregnancy. The aim of this study was to assess the seroprevalence of coinfections of malaria, hepatitis B (HBV), human immunodeficiency virus (HIV), and syphilis among pregnant women attending antenatal clinics (ANC) in the Tamale Metropolis. Methods. By means of rapid diagnostic tests (RDTs), pregnant women attending the Tamale Teaching Hospital (TTH) were screened for malaria, HBV infection, HIV infection, and syphilis from March 2013 to February 2015. Haemoglobin (Hb) values, sickling, and glucose-6-phosphate dehydrogenase deficiency (G6PDd) statuses were also assessed using full blood count (FBC), sodium metabisulphite, and methaemoglobin reduction tests, respectively. Logistic regression analysis was performed to estimate the risks/odds ratios (ORs) for the coinfections and other variables (age, gravidity, and time of the first ANC visit) with 95% confidence intervals (CIs) and set p values for accepting any differences at <0.05. Results. Within the two-year study period, data were collected from 3,127 pregnant women. The mean age (SD) of the pregnant women was 28.5 (±5.0) years. Of the total number, seroprevalence was high for malaria (11.6%) and HBV infection (4.2%) and low for HIV infection (1.0%) and syphilis (0.4%) monoinfections. Mal/HBV coinfection was higher (0.7%) when compared with Mal/HIV (0.1%), Mal/syphilis (0.0%), HBV/HIV (0.0%), HBV/syphilis (0.1%), and HIV/syphilis (0.0%) coinfections. The mean Hb (g/dl) for the women with the four monoinfections was significantly different from one another (p=0.009). Pregnant women with malaria infection were about 2 times more likely to be coinfected with HBV even after adjusting for potential confounders (adjusted odds ratio (AOR) = 1.66, 95% CI = 1.04–2.65, p=0.031). Those in their third trimester and visiting the ANC for the first time were significantly less likely to be infected with HBV (AOR = 0.45, 95% CI = 0.28–0.73, p=0.001), with malaria/HBV coinfection (AOR = 0.09, 95% CI = 0.01–0.68, p=0.020), and with any coinfection (AOR = 0.19, 95% CI = 0.06–0.63, p=0.007). Conclusion. A comparatively high seroprevalence of malaria and its coinfection with HBV in pregnant women was observed in this study. Considering the effects that both malaria and HBV have on the liver, it would be expedient to conduct further studies to assess liver function among malaria/HBV-infected individuals, while interventions to prevent coinfections among pregnant women are intensified.