bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Sandblasting Process on Mechanical Properties of ASTM A516 Grade 70 Steel
Authors: Isa Mohd Rashdan , Zaroog Omar Suliman , Yunus Muhammad Aiman , Bavu Vignesh Rao Sanny , Rosmi Norzulhilmi
Published: March 2018

Sandbalsting is a method used for surface treatment and at the same time this process also improves the mechanical properties of the material. ASTM A516 Grade 70 is widely used in industrial sector as it provides very good mechanical properties in tough conditions. The main usage of this material is in moderate and low operating services. This paper focus on the effect of sandblasting process on ASTM A516 Grade 70 on improving the mechanical properties and fatigue life of this material. Samples have been blasted with sand grade SAE G-80. The focus of this paper is the result of the microhardness, tensile and fatigue test before and after the sandblasting process to study the improvement in mechanical properties as well as the fatigue life. The research was extent to the microstructure analysis using SEM to study the change in microstructure after sandblasting process and fatigue test. Result shows that the hardness increases with respect to blasting time. Result also shows 2.3% increment in tensile strength after sandblasting and there is significant increment in fatigue life. Result also shows that the sandblasting process decreases the grain size of the material. It was proven that the sandblasting process will increase the hardness and decrease the grain size of the material with respect to sandblasting time. At the same time, there is a significant improvement in mechanical properties and fatigue life by applying sandblasting process on the tested material.
Evaluation for Chaos in EDM Generated Surface Topography
Authors: Aich Ushasta , Banerjee Simul
Published: March 2018

Machined surface carries the inherent features of machining process. Investigation of surface topography generated by machining process is helpful to extract the features of surface development process. In the present study, roughness profiles measured on machined surface generated by EDM are considered as time series and used for extraction of inherent features of surface topography through phase space reconstruction. Presence of self-similarity in surface topography is assessed by estimating a second order fractal dimension, called as correlation dimension. Saturation of correlation exponents with the increase of embedding dimension indicates the presence of chaos in surface topography.
Relationship between Compressive Residual Stress Relaxation and Microhardness Reduction after Cyclic Loads on Shotpeened ASTM A516 Grade 70 Steel
Authors: Isa Mohd Rashdan , Zaroog Omar Suliman , Ali Fareg S.
Published: March 2018

Shot peening process is a cold performed function to enhance the mechanical properties which is widely used in many industries. This process introduces compressive residual stress which was proven to increase the fatigue life, geometry stability and corrosion resistance. However, the benefit of the residual stress is still unstable due to the relaxation during the operation. This paper will study on the trend of the relaxation of residual stress against cyclic loading as well as the change in the hardness. The material used in this study is carbon steel ASTM A516/ SA 516 Grade 70. Shot peening process with steel shots was applied to the samples to introduce compressive residual stress in the samples. Cyclic load was applied to samples after shot peening process with low load of 52Mpa (20% of Yield Strength) and high load of 208Mpa (80% of Yield Strength). The measurement of residual stress using X-Ray diffraction and hardness test was done on the samples to study the trend of the relaxation of residual stress and the change in hardness values. The result shows that more relaxation of residual stress occurs if the applied cyclic load is higher. The change of hardness trend is found non-sequenced in this study due to random coverage of shot peening.
Calculation Method of Curvature Radius and Bending Deformation of Titanium Alloy under Multiple Laser Shocks
Authors: Zhu Ran , Zhang Yong Kang , Sun Gui Fang , Li Pu , Su Bo Yong , Xu Pei , Zhao Yong , Huang Jian Yun
Published: March 2018

TC4 titanium alloy plate was processed under multiple laser shocks and bending deformation was studied. A method was proposed to determine the curvature radius of bending deformation of metal plate under multiple laser shocks based on the theoretical model of curvature radius of bending deformation and the eigenstrain field was calculated by a modified finite element analysis method. Effect of shock wave peak pressure and the number of impacts on the curvature radius was studied. Results show that bending deformation increases rapidly at the beginning and then it stops growing. Bending deformation increases rapidly with the increase of the number of impacts and it cannot increase after three impacts.
Sintering Effect on Magnetite-to-Hematite Structural Conversion of As-Prepared Fe2+Cr0.2Fe1.8O4 Nano-Ferrites
Authors: Amer M.A. , Matsuda Atsunori , Kawamura G. , Meaz Talaat , El-Shater Reda , Fakhry F.
Published: March 2018

This research presents effect of sintering temperature T and structural transition process on magnetic and optical properties of as-prepared magnetite Fe2+Cr0.2Fe1.8O4 nanoferrites which synthesized by Co-precipitation method and sintered at different T. Structural phase of crystal lattice was converted from-cubic magnetite-to-maghemite-to-hexagonal hematite with T. Specific surface area S revealed decrease against crystallite size R. Saturation magnetization MS proved dependence on R and porosity P. Strain behavior Ԑ enhanced band gap energy Eg.
Strength and Microstructural Properties of Mortar Containing Soluble Silica from Sugarcane Bagasse Ash
Authors: Kusbiantoro Andri , Embong Rahimah , Abd Aziz Azrina
Published: March 2018

Sugarcane bagasse is among the abundantly available waste in agriculture industry. The proportion of siliceous ashes after the incineration process is one of the attractive features in sugarcane bagasse. However, its low bulk density would result in an additional issue for further use as cement replacement material, since higher replacement volume will bring more hydrophilic particles of sugarcane bagasse ash into the mixture. Therefore this research aims to extract the reactive silica from sugarcane bagasse ash and increase its bulk density by converting it into soluble form. The process was divided into three stages, which were pre-treatment and incineration of sugarcane bagasse, conversion into soluble form, and production of mortar specimen. Soluble silica from sugarcane bagasse ash was used to partially replace cement content in mortar, hence its effect on the hydration process can be evaluated. Compression test and scanning electron microscope analysis were performed to observe its effect on the strength and microstructural development of mortar framework. The results show that the inclusion of soluble silica would enhance the early hydration rate and improve the consolidation of cement matrix via additional calcium silicate hydrate formation, which would increase the capability of internal mortar framework to distribute loads and achieve higher strength.
Durability of Sustainable Self-Consolidating Concrete
Authors: Mohamed Osama Ahmed , Al Hawat Waddah , Najm Omar Fawwaz
Published: March 2018

Supplementary cementitious materials such as fly ash, silica fume and ground granulated blast furnace slag (GGBS) have been used widely to partially replace cement in producing self-consolidating concrete (SCC). The production of cement is associated with emission of significant amounts of CO2 and increases the human footprint on the environment. Fly ash, silica fume, and GGBS are recycled industrial by-products that also impart favorable fresh and hardened properties on concrete. This study aims to assess the effect of the amounts of fly ash and silica fume on strength and chloride penetration resistance of concrete. Rapid Chloride Penetration Test (RCPT) was used to assess the ability of SCC to resist ingress of chlorides into concrete. SCC mixes with different dosages of fly ash and silica fume were developed and tested at different curing ages. Test results showed that replacing 20% of cement with fly ash produced the highest compressive strength of 67.96 MPa among all fly ash-cement binary mixes. Results also showed that replacing15% of cement with silica fume produced the highest compressive strength of 95.3 MPa among fly ash-cement binary mixes. Using fly ash and silica fume consistently increased the concrete resistance to chloride penetration at the early ages. Silica fume at all dosages results in low or very low levels of chloride penetration at all curing ages of concrete.
Effect of Construction Material on Greenhouse Gases Emission and Energy Use for Residential Buildings
Authors: Song Lih Yau , Tsai Meng Ting , Yadav Rina
Published: March 2018

This research work shows how building construction material effects environment, it is based on the performance of ecofriendly (mud) and non-ecofriendly (concrete) materials on the similar residential buildings, located in the climate of Delhi, India. Comparative study of Mud and concrete has been performed. The analysis of each case study includes the calculation of annual carbon emission and energy use, was simulated by using Autodesk Revit software (version2015). As per result, it is clearly visible that by using ecofriendly material we are able to save 93% annual energy cost.
Quantitative Determination of Calcium Hydroxide by Using Near-Infrared Spectroscopy
Authors: Sangpongpitthaya Tanyapa , Christy Alfred A. , Thorstensen Rein Terje
Published: March 2018

Calcium hydroxide (CH) is a by-product from hydration reaction of cement along with calcium silicate hydrate (C-S-H) gel. It helps to protect the steel reinforcements in concrete structures from corrosion process due to carbonation. The presence of calcium hydroxide provides a basic environment (pH˃10) that induces the formation of passive oxide film and keeps steel structures from corrosion. The detection and quantification of calcium hydroxide in concrete structures are important to understand the nature and state of the steel structures in concretes. In this research work, the variation of calcium hydroxide to calcium silicate ratios in cement were measured by using near-infrared spectroscopy (NIR). The first overtone of the OH groups in calcium hydroxide absorbs at 7082 cm-1 and this absorption peak can be used as a quantitative measure of calcium hydroxide in samples. Correlation plot between second derivative absorbance intensity at 7082 cm-1 with different mixtures of calcium hydroxide in calcium silicate base. The amount of calcium hydroxide in calcium silicate base was established. This calibration plot was used as basis for determining calcium hydroxide content in unknown concrete samples. Concrete samples for the quantitative determination of calcium hydroxide were prepared from standard cement samples and cement samples with or without pozzolan along with various water to cement ratios. The results show that all samples analyzed in this work contain calcium hydroxide in varying amounts. This variation reflects the composition of the cement and concrete samples.
Evaluation of the Influence of the Waste Originated by the Production of Titanium Dioxide (URM) on the Physical-Mechanical Properties of Coating Mortars
Authors: de Albuquerque Diana Dayse Mariano , Andrade Neto José , Amorim Júnior Nilson Santana , Santos Vitor Souza , Ribeiro Daniel Véras
Published: March 2018

Waste generation is one of the main problems of contemporary society, resulting in high economic costs and environmental impacts, such as the contamination of water sources, groundwater and soil. In this context, there is the unreacted mineral (URM), a waste originated by the production of titanium dioxide, which currently does not have an effective reuse plan, being deposited in a controlled landfill, generating a high economic expense for the generating company. In this way, the present work aims to evaluate the influence of URM on the properties of coating mortars. Firstly, it was carried out a physical, chemical and mineralogical characterization of the waste and, afterwards, coating mortar was prepared with additions of 0% (reference), 5%, 10% and 15% of the waste, in relation to the cement mass. The mortars were evaluated for density, porosity, capillary absorption by capillarity and mechanical strength. It was noted that the waste increased the mechanical strength of the mortars studied and did not significantly influence the other evaluated properties. Therefore, the incorporation of the waste into mortars is an interesting and feasible alternative for the destination of the URM.
Compressive Behavior of Circular Concrete Columns Confined by Basalt Fiber Reinforced Polymer (BFRP)
Authors: Suon Sakol , Saleem Shahzad , Pimanmas Amorn
Published: March 2018

This paper presents an experimental study on the compressive behavior of circular concrete columns confined by a new class of composite materials originated from basalt rock, Basalt Fiber Reinforced Polymer (BFRP). The primary objective of this study is to observe the compressive behavior of BFRP-confined cylindrical concrete column specimens under the effect of different number of layers of basalt fiber as a study parameter (3, 6, and 9 layers). For this purpose, 8 small scale circular concrete specimens with no internal steel reinforcement were tested under monotonic axial compression to failure. The results of BFRP-confined concrete specimens of this study showed a bilinear stress-strain response with two ascending branches. Consequently, the performance of confined columns was improved as the number of BFRP layer was increased, in which all the specimens exhibited ductile behavior before failure with significant strength enhancement. The experimental results indicate the well-performing of basalt fiber in improving the concrete compression behavior with an increase in number of FRP layers.
Strength and Durability of High Performance Concrete Doped New Low Clinker Cementing Material
Authors: Huang Shuai , Lyu Yue Jun , Peng Yan Ju , Zhang Li Fang
Published: March 2018

A new low clinker cementing material applying to different concrete strength is developed in this paper. The experiential results show that standard consistency water consumption of the new material is less than the ordinary material; and the particle size is better than the ordinary material. And the cracking performance of the concrete made by the new material is far better than the performance of the concrete made by the ordinary material. Furthermore, the shrinkage of the concrete made by new material is less; and the resistance ability to carbonation is higher. Especially, our proposed new material could make the gel body dense and become six components of concrete into four, which simplifies the production process of concrete mixing station. At the same time, the prepared concrete made by the new material has better construction performance, volume stability and high durability. Unfortunately, the initial and final setting time of the new material are slightly longer. However, the initial and final setting time are still able to meet the national requirements. And most of all the new material meets the requirements of green high performance concrete.
Synthesis and Characterization of Sm1-xZrxFe1-yMgyO3 (x, y = 0.5, 0.7, 0.9) as Possible Electrolytes for SOFCs
Authors: Abdalla Abdalla Mohammed , Hossain Shahzad , Radenahmad Nikdalila , Petra Pg Mohammad Iskandar , Somalu Mahendra Rao , Rahman Seikh M.H. , Eriksson Sten G. , Azad Abul Kalam
Published: March 2018

The novel perovskite oxide series of Sm1-xZrxFe1-yMgyO3 (x,y = 0.5, 0.7, 0.9) were synthesized by solid state reaction method. X-ray diffraction (XRD), Rietveld refinement, scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and conductivity analysis were carried out. XRD patterns of sintered materials revealed the shifted Bragg reflection to higher angle for the higher content of Zr and Mg. This is related to the ionic size of the dopant elements. Rietveld refinement showed that all compounds crystallized in cubic space group of Fm-3m. SEM images showed that the grains were well defined with highly dense surfaces makes it potential as an electrolyte material in solid oxide fuel cells (SOFCs) or gases sensors. Impedance spectroscopy at 550-800 °C shows that conductivity is higher at higher temperature. Sm0.5Zr0.5Fe0.5Mg0.5O3 shows the highest conductivity of 5.451 × 10-3 S cm-1 at 800 °C. It was observed that 50% molar ratio of Mg and Zr doping performed highest conductivity.
Tensile Mechanical Properties of HTPB Propellant at Low Temperature
Authors: Chen Xiang Dong , Chang Xin Long , Zhang You Hong , Wang Bin , Zhang Qing , Zhang Xiang
Published: March 2018

To study the low temperature effects of tensile mechanical properties on Hydroxyl-terminated polybutadiene (HTPB) propellant, a quasi-static mechanical experiment was conducted. The results show that tensile mechanical parameters are closely related to strain rate and low temperature. With the decrease of temperature and increase of strain rate, the modulus and tensile strength of HTPB propellant increase obviously. Based on the time-temperature equivalence principle (TTEP), the master curves of tensile strength and initial modulus for HTPB propellant were obtained, which can facilitate the structural integrity analysis of the propellant. The damage of propellant is matrix tearing and dewetting between the filled particles and matrix.
UV Photopatternability and Electrical Properties of GnF/SU-8 Composites Controlled by GnF Concentration
Authors: Woo Seung Pyo , Park Sung Min , Nam Gyung Mok , Choi Young , Park Sang Heon , Yoon Sang Hee
Published: March 2018

The GnF/SU-8 composites are new polymer matrix composites (PMCs) composed of graphite nanoflakes (GnFs) bound together by SU-8 photoresist. The PMCs therefore have excellent ultraviolet (UV) photopatternability and high electrical properties. In spite of the unique material properties of GnF/SU-8 composites, much still remains uncertain about their controllability in both UV photopatternability and electrical properties. Here, we investigate 7 kinds of GnF/SU-8 composites having different GnF concentrations of 5.0 to 25.0 wt.% to characterize the changes in the UV photopatternability (i.e., polymerized thickness and photopattern quality) and electrical conductivity of GnF/SU-8 composites caused by a variation in GnF concentration. The polymerized thickness of GnF/SU-8 composites is measured to be in the range of 4.06 to 23.99 μm, which is inversely proportional to GnF concentration and also directly proportional to UV dose (i.e., 345 to 3,450 mJ/cm2) because of the screening effect of GnF existed in the composites; the photopattern quality at the edge is in inverse proportion to GnF concentration. An increase in GnF concentration leads to a significant change in the electrical conductivity of GnF/SU-8 composites in a proportional way (up to 25.34 S/m). The GnF/SU-8 composites are expected to be widely used as UV photopatternable and electrically conductive PMCs for diverse engineering applications.
Conversion of Electric Arc Furnace Dust into Ceramics Using Thermodynamic Calculations and Experimental Work
Authors: Mostafa Ahmad , Shahtout Mohamed , Al Afeefi Tariq , Medraj Mamoun
Published: March 2018

Steelmaking is accompanied with releasing a large quantity of solid particle in the form of dust. Electric arc furnace dust (EAFD) is known to have high pH number and traces of heavy metals. The objective of this work was to find a suitable procedure for converting the dust waste into inert and useful byproducts using thermodynamic calculations and experimental investigation. The physical, chemical and mineralogical characteristics of initial EAFD were analyzed using different techniques, such as: X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), grain size analysis and metallography. The pH measurement procedure was carried out in accordance with the standard test method for pH of soils “ASTM 4972-95a”. The results of XRD, SEM and EDS analysis were consistent and showed that Fe2O3, CaO, Al2O3, SiO2, MgO, ZnO and traces of other oxides are in the main composition of the EAFD batches with different relative amounts. Furthermore, the particle size measurements revealed that the EAFD particles are in the 0.1 to 394 μm size range. The pH number was ranging between 11.15 and 12.21 for all measurements. The experimental results were used as input data for thermodynamic calculations and accordingly SiO2 and Al2O3 were among the candidates for making ceramic materials through forming glass regions that surround and encapsulate the iron oxide particles. SiO2 modified samples exhibited better apparent structural properties than other compositions. Whereas Al2O3-modified samples showed variation in the product color. Thus, it is concluded from this work that a mixture of EAFD can be modified by 5-20 wt.% of SiO2 and then fired at 1100°C to make inert ceramic materials with reasonable mechanical properties.
Synthesis of Silica Materials from the Slurry Waste
Authors: Shen Zih Yao , Lu Zhong Chen , Liu Yun Chi , Lee Maw Tien
Published: March 2018

In solar energy industry, large amount of slurry wastes were produced during the wafer dicing process. The slurry waste contains silicon, silicon carbide and cutting oil. In this study, silicon in the slurry waste was treated with sodium hydroxide to produce a liquid mixture of the sodium silicate. The residue of the reaction was silicon carbide. The liquid mixture was separated to be a sodium silicate solution and used as a silica precursor for producing the silica powder and a hydrophobic silica aerogel by using the sol-gel method. The products were characterized by Fourier transformation infrared spectroscopy (FTIR) and powder X-ray diffraction (pXRD). Experimental results show that the characteristics of the products produced from the slurry waste are similar to that obtained by using the pure sodium silicate solution. It indicates that the wafer dicing slurry waste has a high potential to be a resource for other industries.
Surface Functionalization of Two-Dimensional Vertically Aligned Semiconductor Heterojunctions
Authors: Zhuiykov Serge , Hai Zhen Yin
Published: March 2018

Large-scale fabrication of two-dimensional (2D) nanomaterials by vapor phase depostion enabled the establishment of vertically aligned semiconductor herterojunctions. However, the property modulation of 2D semiconductor heterojunctions remains chanlleging within such thin layers. Herein, we proposed a general strategy towards the surface functionlization of 2D semiconductor heterojunctions simply by two-step atomic layer deposition (ALD) process with following post-annealing. TiO2-WO3 heterojunction was taken as a typical case in this work and its electrochemical properties were significantly improved via the proposed strategy. This strategy may open a new pathway for facile functionalization of 2D nanomaterials for the energy conversion and storage devices.
Enhanced Formation of the Carbon Microcoils by the Stepwise Type Manipulation of CS2 Flow Injection
Authors: Lee Na Young , Kim Sung Hoon
Published: March 2018

Carbon coils were synthesized using C2H2 as source gas and CS2 as an incorporated additive gas under the thermal chemical vapor deposition system. The flow rate of CS2 varied according to the different reaction processes. Geometries of as-grown carbon nanomaterials were developed from vine-type into coil-type with increasing CS2 flow rate from 5 to 20sccm. Above 20sccm of CS2 flow rate, indeed, most of them were appeared as the tiny-sized wavelike nanocoil type geometries. To develop the double helix-type microcoils, namely the carbon microcoils, the injection of CS2 flow was manipulated as the stepwise type on/off-cycle manner. Under the specific condition of the on/off-cycle number, the density of the carbon microcoils was enhanced. The cause for the enhanced formation density of the carbon microcoils by the stepwise type manipulation of CS2 flow injection was suggested and discussed.
Memory Follicular Helper Invariant NKT Cells Recognize Lipid Antigens on Memory B Cells and Elicit Antibody Recall Responses
Authors: Chen Zuolong , Zhu Shasha , Wang Lu , Xie Di , Zhang Huimin , Li Xiang , Zheng Xihua , Du Zhiwei , Li Jie , Bai Li
Published: March 2018

Invariant NKT (iNKT) cells have been shown to help B cells in a cognate or noncognate manner; however, whether cognate iNKT cell help induces B cell memory responses remains controversial, and the underlying mechanisms are still unclear. In this study, we demonstrated that, in the absence of follicular helper T cells, cognate iNKT cell help could promote B cell memory responses in mice that were dependent on the formation of memory follicular helper iNKT (iNKTFH) cells and their interactions with memory B cells in recall responses. Generation of memory iNKTFH cells required lipid Ag presentation by dendritic cells but not by B cells. Upon rechallenge, memory iNKTFH cells recognized lipid Ags presented by memory B cells, which recalled iNKTFH effector cells and elicited B cell memory responses. However, LPS, which promoted the synthesis of self-lipids, failed to elicit recall responses in the absence of exogenous lipid Ags.
Deregulated Mucosal Immune Surveillance through Gut-Associated Regulatory T Cells and PD-1+ T Cells in Human Colorectal Cancer
Authors: Fujimoto Hanae , Saito Yoriko , Ohuchida Kenoki , Kawakami Eiryo , Fujiki Saera , Watanabe Takashi , Ono Rintaro , Kaneko Akiko , Takagi Shinsuke , Najima Yuho , Hijikata Atsushi , Cui Lin , Ueki Takashi , Oda Yoshinao , Hori Shohei , Ohara Osamu , Nakamura Masafumi , Saito Takashi , Ishikawa Fumihiko
Published: March 2018

Disturbed balance between immune surveillance and tolerance may lead to poor clinical outcomes in some malignancies. In paired analyses of adenocarcinoma and normal mucosa from 142 patients, we found a significant increase of the CD4/CD8 ratio and accumulation of regulatory T cells (Tregs) within the adenocarcinoma. The increased frequency of Tregs correlated with the local infiltration and extension of the tumor. There was concurrent maturation arrest, upregulation of programmed death-1 expression, and functional impairment in CD8+ T cells (CTLs) isolated from the adenocarcinoma. Adenocarcinoma-associated Tregs directly inhibit the function of normal human CTLs in vitro. With histopathological analysis, Foxp3+ Tregs were preferentially located in stroma. Concurrent transcriptome analysis of epithelial cells, stromal cells, and T cell subsets obtained from carcinomatous and normal intestinal samples from patients revealed a distinct gene expression signature in colorectal adenocarcinoma–associated Tregs, with overexpression of CCR1, CCR8, and TNFRSF9, whereas their ligands CCL4 and TNFSF9 were found upregulated in cancerous epithelium. Overexpression of WNT2 and CADM1, associated with carcinogenesis and metastasis, in cancer-associated stromal cells suggests that both cancer cells and stromal cells play important roles in the development and progression of colorectal cancer through the formation of a tumor microenvironment. The identification of CTL anergy by Tregs and the unique gene expression signature of human Tregs and stromal cells in colorectal cancer patients may facilitate the development of new therapeutics against malignancies.
Thermal Performance Evaluation of a New Close-Coupled Cooling Solution including Cooling Failure Analysis
Authors: Sahini Manasa , Agonafer Dereje
Published: March 2018

The objective of this work is to introduce and evaluate a new end-of-aisle cooling design which consists of three cooling configurations. The key objectives of close-coupled cooling are to enable controlled cooling of information technology (IT) equipment, flexible and modular design, and the containment of hot air exhaust from the cold air. The thermal performance of the proposed solution is evaluated using computational fluid dynamics modeling. A computational model of a small size data center room has been developed. The room is modeled to be a hot aisle containment setup, i.e., the hot air exhaust exiting for each row is contained and directed within a specific volume. The cold aisle is separated from the hot aisle by means of banks of heat exchangers (HXs) placed on either side of the containment aisle. Based on the placement of rack fans, the design is divided into three sub-designs—Case 1: passive HXs with rack fan walls; Case 2: active HXs (coupled with fans) with rack fan walls; Case 3: active HXs (coupled with fans) with no rack fans. The cooling performance is calculated based on the thermal and flow parameters obtained for all three configurations. The computational data obtained has shown that the Case 1 is used only for lower system resistance IT. However, Cases 2 and 3 can handle denser IT systems. Case 3 is the design that can consume lower fan energy and handle denser IT systems. The article also discusses the cooling behavior of each type of design under cooling failure conditions with Case 2 showing better cooling redundancy compared with other two cases.
Evaluation of different atlas selection strategies for multi-atlas segmentation of low-dose computed tomographic images of whole-body positron emission tomography/computed tomography
Authors: Wang Hongkai , Zhang Nan , Huo Li , Zhang Bin
Published: March 2018

ABSTRACT

Background and Objectives:

The increasing clinical use of torso positron emission tomography/computed tomography (PET/CT) demands automated segmentation of torso organs from PET/CT images. We attempt to use the multi-atlas segmentation approach for trunk organ segmentation from the low-dose CT images of PET/CT. Since atlas selection is a prerequisite step for multi-atlas segmentation, this study focuses on evaluating the performance of different atlas selection strategies for torso organ segmentation.

Methods:

We evaluated two criteria for atlas selection, including image similarity and body mass index (BMI) difference between the atlas and the target image. Based on the two criteria, ten atlases are selected and registered to the target image, followed by the label fusion step to achieve final segmentation.

Results:

The BMI criterion yields comparable segmentation accuracy to the image similarity criterion but with much less computation time. All the evaluated atlas selection methods have Dice >0.9 for the lungs, heart, and liver and Dice < 0.85 for the skeleton, spleen, and kidneys. The inter-method differences are not significant for the high-contrast and big-sized organs such as skeleton, lungs, heart, and liver. For the low-contrast and smaller-sized organs such as spleen and kidneys, none of the atlas selection methods significantly outperforms random atlas selection.

Conclusions:

BMI is an effective and efficient atlas selection criterion for low-dose torso CT images. The spleen and kidneys are difficult to get good segmentation, no matter which atlas selection method is used. It is important to develop more effective atlas selection methods for the spleen and kidneys.
Immunohistochemical expression of hypoxia-inducible factor-1α in stromal cells of vaginal tissue in post-menopausal women with pelvic organ prolapse
Authors: Jakus Ivana Alujević , Jakus Dora , Aračić Nađa , Stipić Ivica , Vilović Katarina
Published: March 2018

Background & objectives:

Pelvic organ prolapse (POP) is a common medical condition that affects adult women of different ages. The support of a normal pelvic floor is the result of complex interactions between ligaments, muscles, connective tissue and vaginal walls. Hypoxia and oxidative stress can reduce protein synthesis in the pelvic muscles that may contribute to muscular atrophy. Hypoxia-inducible factor-1α (HIF-1α) is a transcriptional activator which, expressed in response to hypoxia, activates a number of genes involved in cellular response to hypoxia. However, a potential role of hypoxia and oxidative stress in pathogenesis of POP is not known. This study was aimed to compare the level of HIF-1α immunohistochemical expression in the vaginal stromal cells of postmenopausal women with and without POP.

Methods:

Samples of the vaginal tissue from 120 menopausal women were obtained during surgery, and immunohistochemical expression of HIF-1α was assessed. There were 60 women with POP while 60 women in the control group were without prolapse but with benign gynaecological diseases.

Results:

In post-menopausal women with prolapse, significant differences were observed in the number of HIF-1α-positive stromal cells in the vaginal tissue compared to the control group. There was a significant increase in the number of HIF-1α in the stromal cells of the vaginal tissue in women with prolapse.

Interpretation & conclusions:

Difference in expression of HIF-1α in stromal cells of the vaginal tissue in the post-menopausal women with and without POP suggests that prolonged hypoxia probably has an important role in the aetiopathogenesis of POP.
Effect of bone bank processing on bone mineral density, histomorphometry & biomechanical strength of retrieved femoral head
Authors: Lakhwani O.P. , Jindal M. , Kaur Omkar , Chandoke R.K. , Kapoor S.K.
Published: March 2018

Background & objectives:

Standard processing of the bone grafts involves deep-freezing and sterilization with gamma irradiation which may alter mechanical properties of the bone graft. This study was aimed at measuring the effect of bone bank processing on the mechanical properties of bone allograft and its correlation with bone mineral density [BMD, dual-energy X-ray absorptiometry (DEXA Scan)] and histomorphometric indices.

Methods:

Femoral heads retrieved from patients undergoing hip replacement surgeries were used as the material. Twenty femoral heads were under taken in the study. Each femoral head was cut into two equal cubes. One cube was subjected to BMD measurement using DEXA Scan followed by unilateral compression test. Histomorphometric indices such as trabecular number (Tb. N.), trabecular separation (Tb. S.), trabecular thickness (Tb. T.) and bone volume (B.V.) were calculated on the same specimen by a computer software. The other cube was kept in deep freezer (−76°C) for a minimum of three weeks, followed by gamma irradiation and subjected to similar tests.

Results:

Results were compared in pre- and post-processed bone specimens. A significant loss of biomechanical strength (P<0.001) with mean a loss of 18.90 per cent was found in post-processed samples in uniaxial compression tests. Similarly, BMD (mean decrease by 13.8%, P<0.01) and histomorphometric indices such as Tb. T. (mean decrease by 12.37%, P<0.01), Tb. S. (mean increase by 12.60%, P<0.001) and B.V. (mean decrease by 20.84%, P<0.01) were found. However, Tb. N. was not significantly affected.

Interpretation & conclusions:

The current method of processing of bone allografts i.e. deep-freezing and gamma irradiation appeared to cause a significant reduction in the biomechanical strength of allogenic bone which was more suitable to be use in the morselized form. Appropriate consideration for decreased strength needs to be given when using allogenic bone graft as a structural graft.
Impact of attendance in a daycare centre on depression among elderly in rural Puducherry
Authors: Sarkar Sonali , Kattimani Shivanand , Premarajan K.C. , Roy Gautam
Published: March 2018

Background & objectives:

Depression is higher in the elderly and in the rural areas in India. There is a need for interventions to reduce depression among the elderly and improve their quality of life (QOL). This study was conducted to assess the impact of attendance at a community-based daycare centre in rural Puducherry, India, on depression, cognitive impairment (CI) and QOL of the elderly.

Methods:

This was a before and after intervention study with a daycare centre set up in the village Thondamanatham in Puducherry, India, between January 2013 and January 2014. Socializing activities were held at the centre with psychological counselling. Depression was measured using Geriatric Depression Scale (GDS, short form), CI using the Hindi Mini-Mental Status Examination and QOL using WHO QOL BREF.

Results:

There were 99 males and 164 females; of whom 42.2 per cent attended the daycare centre at least once a month. Significantly higher proportions of elderly had depression among those with lower frequency of attendance at the daycare centre. Irrespective of the pre-intervention status, attendance at the daycare centre reduced the probability of depression by about 51 per cent. There was an improvement in the WHO QOL scores in the social domain among those who attended more than once a month.

Interpretation & conclusions:

GDS scores decreased and WHO QOL scores increased with increasing attendance at the daycare centre. Thus, the intervention was found to be effective in reducing depression and improving QOL of the elderly.
Synthesis and Characterization of Core-Shell Silica-Phosphor Nanoparticles via Sol-Gel Process
Authors: Shin Weon Ho , Kim Seyun , Jeong Hyung Mo
Published: March 2018

Cost-effective functional phosphor nanoparticles are prepared by introducing low-cost SiO2 spheres to rareearth phosphor (YVO4:Eu3+, YVO4:Er3+, and YVO4:Nd3+) shells using a sol-gel synthetic method. These functional nanoparticles are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and general photoluminescence spectra. The SiO2 sphere occupying the interior of the conventional phosphor is advantageous in significantly reducing the cost of expensive rare-earth phosphor nanoparticles. The sol-gel process facilitates the core–shell structure formation; the rare-earth shell phosphor has strong interactions with chelating agents on the surfaces of SiO2 nanoparticles and thus forms layers of several nanometers in thickness. The photoluminescence wavelength is simply tuned by replacing the active materials of Eu3+, Er3+, and Nd3+. Moreover, the photoluminescent properties of the core–shell nanoparticles can be optimized by manipulating the specific contents of active materials in the phosphors. Our simple approach substitutes low-cost SiO2 for expensive rare-earth-based phosphor materials to realize cost-effective phosphor nanoparticles for various applications.
Fabrication of Al2O3 Dispersed Porous Cu by Freeze Drying of CuO-Al2O3/Camphene Slurry
Authors: Kang Hyunji , Riu Doh-Hyung , Oh Sung-Tag
Published: March 2018

Porous Cu with a dispersion of nanoscale Al2O3 particles is fabricated by freeze-drying CuO-Al2O3/camphene slurry and sintering. Camphene slurries with CuO-Al2O3 contents of 5 and 10 vol% are unidirectionally frozen at -30°C, and pores are generated in the frozen specimens by camphene sublimation during air drying. The green bodies are sintered for 1 h at 700°C and 800°C in H2 atmosphere. The sintered samples show large pores of 100 μm in average size aligned parallel to the camphene growth direction. The internal walls of the large pores feature relatively small pores of ~10 μm in size. The size of the large pores decreases with increasing CuO-Al2O3 content by the changing degree of powder rearrangement in the slurry. The size of the small pores decreases with increasing sintering temperature. Microstructural analysis reveals that 100-nm Al2O3 particles are homogeneously dispersed in the Cu matrix. These results suggest that a porous composite body with aligned large pores could be fabricated by a freeze-drying and H2 reducing process.
Recent Developments in H2 Production Photoelectrochemical Electrode Materials by Atomic Layer Deposition
Authors: Han Jeong Hwan
Published: March 2018

The design and fabrication of photoelectrochemical (PEC) electrodes for efficient water splitting is important for developing a sustainable hydrogen evolution system. Among various development approaches for PEC electrodes, the chemical vapor deposition method of atomic layer deposition (ALD), based on self-limiting surface reactions, has attracted attention because it allows precise thickness and composition control as well as conformal coating on various substrates. In this study, recent research progress in improving PEC performance using ALD coating methods is discussed, including 3D and heterojunction-structured PEC electrodes, ALD coatings of noble metals, and the use of sulfide materials as co-catalysts. The enhanced long-term stability of PEC cells by ALD-deposited protecting layers is also reviewed. ALD provides multiple routes to develop improved hydrogen evolution PEC cells.
Аффинные системы функций типа Уолша в симметричных пространствах
Authors: Astashkin Sergei Vladimirovich , Terekhin Pavel Aleksandrovich
Published: March 2018

Изучаются аффинные системы функций типа Уолша в симметричных пространствах. Показано, что такая система может быть безусловным базисом только в $L^2$. В то же время каждая бесселева аффинная система, порожденная функцией $f$ из пространства Зигмунда-Орлича $\operatorname{Exp}L^p$, $p>0$, является системой случайной безусловной сходимости в симметричном пространстве $X$, если и только если $(\operatorname{Exp}L^q)^0\subset X\subset L^2$, где $(\operatorname{Exp}L^q)^0$ - замыкание $L^\infty$ в $\operatorname{Exp}L^q$ и $q=2p/(p+2)$.
Библиография: 20 названий.
Приложения теории сумм произведений к множествам, избегающим несколько линейных уравнений
Authors: Shkredov Ilya Dmitrievich
Published: March 2018

С помощью теории сумм произведений показано, что для произвольного $\kappa \le 1/3$ любое подмножество $\mathbf{F}_p$, избегающее $t$ линейных уравнений
с тремя переменными, имеет мощность, равную $O(p/t^\kappa)$.
Библиография: 26 названий.
La Máscara Refugio o la mirada arquitectónica de John Hejduk
Authors: Ros-García Juan Manuel
Published: March 2018

La arquitectura de John Hejduk se sitúa al margen de reglas convencionales para el análisis proyectual en un momento de acelerada complejidad. Contexto y programa son reinterpretados dentro de un marco actual de transformación global que supera cualquier observación elemental. La realidad de su obra dibujada queda representada a través del poder de la memoria y del proceso dinamizador de la colectividad social, participando en su configuración sin pretender alcanzar necesariamente su materialidad final. Así, en la Máscara Refugio de Buenos Aires construida en 1998 congela el movimiento de su ideación, ejemplificando con ello la libertad ubicumque de toda su obra.
Vers un nouveau Surréalisme. Las fantasías arquitectónicas de Jim Kazanjian.
Authors: Lus Arana Luis Miguel
Published: March 2018

Desde la aparición del movimiento en la primera mitad de los años 20, el maridaje de surrealismo y fotografía ha tenido a la arquitectura como uno de sus objetos privilegiados, produciendo imposibles fantasías arquitectónicas revestidas por el velo de lo real. Con la llegada de los métodos de foto-manipulación digital, esta experimentación se ha multiplicado, dando lugar a una enorme variedad de aproximaciones que juegan con la imagen fotográfica para producir escenarios arquitectónicos imposibles pero fascinantes. El artículo centra su mirada en la obra de Jim Kazanjian, un autor procedente del mundo de la construcción digital que, actuando desde los márgenes de la disciplina, ha producido a lo largo de la última década una obra que combina la pericia técnica con su interés por las atmósferas sombrías de los relatos de H.P. Lovecraft o Algernon Blackwood para producir improbables objetos arquitectónicos de oscura pero delicada belleza.
El análisis de la forma en el diseño arquitectónico: desde el proyecto a la ejecución
Authors: Rossi Adriana , Palmero Luis , De Gregorio Stefania
Published: March 2018

Para cada conjunto de datos de coordenadas experimentales, existen unos datos de partida que van en función de aquellos que consideramos objetivos si nos ocupamos de especificar las tolerancias de las herramientas empleadas. La interpretación del modelo geométrico requiere reflexiones metodológicas fundadas. En la presente investigación, la pregunta podría ser: ¿cuál fue la configuración de los elementos proyectados de fachada? El cálculo matemático apoya la hipótesis, pero es el ensayo con instrumentos el que legitima lo que hemos elegido, ya que determina la diferencia entre el modelo experimental numérico y el más abstracto de las ideas. Estas informaciones permiten definir hipótesis sobre conflictos generados durante los trabajos en ejecución.
Docencia colaborativa en BIM. Desde la tradición y dirigida por la expresión gráfica arquitectónica
Authors: León Cascante Íñigo , Pérez Martínez José Javier
Published: March 2018

La inclusión de la metodología BIM (Building Information Modeling) en los estudios de Grado de Arquitectura es un hecho ineludible. Esta implantación afecta, especialmente, al modo de plantear la docencia en Expresión Gráfica Arquitectónica (EGA). Tras el estudio de los congresos y publicaciones más relevantes en la materia, se ha desarrollado un Proyecto de Innovación Educativa basado en la colaboración entre asignaturas y dirigido por el Área EGA. Se definen las características de la implantación, en la que se concluye que la clave está en la colaboración, donde EGA tiene un papel líder. Se trata de plantear metodologías docentes innovadoras para BIM, sin rechazar ciertas técnicas tradicionales imprescindibles de EGA.
La perspectiva curvilínea como resultado de la medición arquitectónica y de los condicionantes espaciales en la obra de Antonio López
Authors: Serrano León David
Published: March 2018

Este estudio pretende demostrar que la perspectiva curvilínea en la obra de Antonio López es obtenida, exclusivamente, a través de la medición de la realidad. También la arquitectura juega un papel decisivo pues su naturaleza rectilínea evidencia la distorsión de las formas que depende de los condicionantes espaciales que utilice el artista. El resultado es un espacio pictórico que aúna principios geométricos, metodológicos y ópticos.
Luz estructurada en la reconstrucción digital de detalles arquitectónicos
Authors: León Robles Carlos , Reinoso Gordo Juan Francisco , Mataix Sanjuán Jesús
Published: March 2018

El interés en la catalogación del patrimonio histórico ha supuesto un creciente desarrollo de las técnicas de escaneado en tres dimensiones en los últimos años. En el presente trabajo se introduce la técnica de luz estructurada como un método de digitalización que, a pesar de sus limitaciones, es una potente herramienta para el levantamiento de detalles arquitectónicos.

Los resultados obtenidos con la luz estructurada en el levantamiento arquitectónico del Hospital Real de la Universidad de Granada han sido satisfactorios como sustitutivo o complemento al escáner láser y la fotogrametría digital.