bluuebunny/crossref_metadata_2025 huggingface dataset:
Microstructure Evolution and Stress Rupture Properties of DD6 Single Crystal Superalloy after Overheating
Authors: Liu Shi Zhong , Shi Zhen Xue , Han M. , Li Jia Rong
Published: June 2017

The second generation single crystal superalloy DD6 after standard heat treatment was respectively overheated at 1100°C, 1150°C, 1200°C, 1250°C, 1300°C, 1320°C for 1h and air cooled. The effect of overheating on the microstructure and stress rupture properties at 980°C/250MPa of the alloy was investigated. The results showed that the size of γ′ phase was slightly increased overheating at 1100°C, 1150°C and 1200°C. The size of γ′ phase had a big increase and its size distribution was very uneven after overheating at 1250°C. The small part of γ′ phase has serrated γ′/γ phase surface as a result of un-completely solution and the irregular small γ′ phase was in the majority when overheated at 1300°C. While all the irregular small γ′ phase precipitated again after completely solution when overheated at 1320°C. There was no fine second γ′ phase in the γ matrix channel of the alloy after standard heat treatment and overheating at 1320°C. But the fine second γ′ phase precipitated in the γ matrix channel after overheating at every temperature of 1100 °C~1300°C. No obvious change of the stress rupture life was found after overheating at 1100°C, 1150°C, 1200°C and 1250°C. The stress rupture life considerably reduced after overheating at 1300°C, whereas slightly reduced after overheating at 1320°C. The appearance of the raft had almost no change after overheating at 1100°C. With increasing of overheating temperature from 1100°C to 1250°C, the length of raft became shorter and the width thickening. The γ phase formed the wavy raft after overheating at 1300°C and 1320°C and the thickness of latter was larger than that of the former. Finally, the relationship between the microstructural evolution and stress rupture properties of the alloy after overheating was discussed.
Microstructure and Mechanical Properties of Mg-Er-Zn Alloys with LPSO Phase
Authors: Cui Shu Jing , Geng Hao Ran , Teng Xin Ying , Wu Xiang Wei , Jia Peng , Wu Chen
Published: June 2017

As-cast Mg-3Er-xZn (x = 0, 0.5, 1 and 2 at.%) alloys were prepared by a cast ingot metallurgy process. The effect of Zn contents on the microstructure and phase constitution of the alloys was investigated by optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and transmission electronic microscope (TEM). The results revealed that the as-cast Mg-3Er alloy mainly consisted of α-Mg phase and MgEr eutectic phase. Typically, a small amounts of LPSO phase was precipitated at grain boundaries by adding 0.5 at.% Zn into Mg-3Er alloy. With the addition of 1 at.%Zn, the volume fraction of LPSO phase increased obviously. When the addition of Zn increased to 2 at.%, the volume fraction of LPSO phase decreases and Mg8ZnEr phase forms at grain boundaries. Tensile test indicated that Mg-3Er-1Zn alloy exhibits the excellent mechanical properties. The tensile strength, yield strength and elongation of Mg-3Er-1Zn alloy are 213 MPa, 187.6 MPa and 5.52%, increased by 38.8%, 60% and 3.19%, respectively, corresponding to the alloy without Zn addition. The excellent mechanical properties could be attributed to the introduction of Zn element in alloys, which leads to the strengthening of LPSO phase and grain refinement of α-Mg.
Microstructure and Property Calculation of Three Typical Second Generation Single Crystal Superalloys
Authors: Yue Xiao Dai , Li Jia Rong , Wang Xiao Guang , Shi Zhen Xue
Published: June 2017

To theoretically evaluate three widely used second generation single crystal superalloys-PWA1484, ReneN5 and DD6, the alloy densities, phase graphs, TCP contents, d-electron energy, and creep rupture lives were calculated, and the calculation results were analyzed combined with actual data. Results showed that among the three alloys, PWA1484 had the greatest density, secondly was DD6, and ReneN5’s density was the lowest. The PWA1484 alloy was most likely to precipitate TCP due to its highest d-orbital energy level; the ReneN5 alloy had a medium d-orbital energy level, but its high Cr content induced it to precipitate the most TCP types; the DD6 alloy had the least chance to precipitate TCP phases because of its lowest d-orbital energy level as well as lowest Cr content. It is concluded that thermodynamic calculation had the ability to simulate TCP types and TCP content at steady states, while d-orbital energy concept was capable of exhibiting the alloys in sequence of TCP precipitation potential. Mere thermodynamic calculation will lead to comparatively conservative results, including more TCP types, higher TCP contents and lower rupture lives. Analyzing the thermodynamic and d-orbital energy calculations comprehensively, it can be considered that the DD6 alloy has the most stable microstructure among the three single crystal superalloys.
Temperature Memory Effect of Ti-Ni-Hf-Y High Temperature Shape Memory Alloy
Authors: Li Jun , Yi Xiao Yang , Gao Wei Hong , Song Wen Long , Meng Xiang Long
Published: June 2017

Temperature memory effect in the solution-treated Ti-Ni-Hf-Y high temperature shape memory alloy (HTSMA) was investigated. The results showed that the temperature memory effect induced by the partial cycling could be detected in the subsequent complete transformation cycling for the solution-treated Ti-Ni-Hf-Y alloy. The temperature memory effect is one-time phenomenon. However, the temperature memory effect could last at least 20 times when the sample was employed 10 times complete thermal cycles. Multiple-steps temperaure memory effect can be observed as the sample undergoes the lower temperature partial thermal cycle in sequence. The mechanisms of the temperature memory effect were discussed in this paper.
Effect of Y2O3 Coating on the Interface and Mechanical Properties of SiC Fiber Reinforced GH4738 Composites
Authors: Li Pei Huan , Zhang Yong , Qu Xuan Hui
Published: June 2017

To prevent the strong interfacial reactions in SiC fiber reinforced nickel-based superalloys matrix composites, yttrium oxide (Y2O3) was used as the barrier coating by reaction magnetron sputtering method. Compared with the composites without coating, after the high temperature hot isostatic pressing (HIP), Y2O3 coating effectively protected the SiC fibers from the interfacial reactions, and no element diffusion can be observed between the fibers and the matrix. The elevated temperature tensile tests were performed on both SiC/GH4738 and SiC/Y2O3/GH4738 composite. The results indicated that the strength of the composites with Y2O3 coating can increase about 35% in comparison with the composites without coating.
Non-Isothermal Crystallization Kinetics of Mg61Zn35Ca4 Glassy Alloy
Authors: Zhang Dao , Lu Wang Shu , Wang Xiao Yan , Yang Sen
Published: June 2017

The non-isothermal crystallization kinetics of Mg61Zn35Ca4 glassy alloy prepared via melt-spinning were studied by using isoconversion method. The crystalline characterization of Mg61Zn35Ca4 was examined by X-ray diffraction. Different scanning calorimeter was used to investigate the non-isothermal crystallization kinetics at different heating rates (3-60 K/min). The calculated value of Avrami exponent obtained by Matusita method indicated that the crystalline transformation for Mg61Zn35Ca4 is a complex process of nucleation and growth. The Kissinger-Akahira-Sunose method was used to investigate the activation energy. The activation energy of crystallization varies with the extent of crystallization and hence with temperature. The Sestak-Berggren model was used to describe the non-isothermal crystallization kinetics.
Diffusion of Ce-Al Melts Measured by Sliding Cell Technique
Authors: Chen Cheng , Hu Jin Liang , Zhong Lang Xiang , Zhang Bo
Published: June 2017

The diffusion behavior of Ce-Al alloy melt at three temperatures of 943K, 953K and 963K was investigated by sliding shear method. The inter-diffusion constants D show Arrhenius-type temperature dependence in the investigated regimes. Compared with the previous results achieved in Ce-Cu melt, liquid Ce-Al displays a much slower diffusion behavior and rather higher activation energy ED, which was caused by the strong interaction between Ce and Al.
Properties of Ni0.5Zn0.5Fe2O4/Fe76Si9B10P5 Bulk Soft Magnetic Composites by Annealing Treatment
Authors: Ren Ji Hang , Zhao Zhan Kui
Published: June 2017

Iron-based amorphous alloys have attracted technological and scientific interests due to their excellent soft magnetic properties. In the present study, Ni0.5Zn0.5Fe2O4/Fe76Si9B10P5 soft magnetic composites cylinder of 15 mm diameter and 3 mm thickness was prepared by spark plasma sintering at the temperature of 780 K. The amorphous Fe-based soft magnetic composites Ni0.5Zn0.5Fe2O4/Fe76Si9B10P5 exhibited good magnetic properties after annealing treatment at temperature ranging from 643 K to 743 K. The beneficial effects of treatment under different temperatures were discussed in terms of the improved magnetic performance of Ni0.5Zn0.5Fe2O4/Fe76Si9B10P5 soft magnetic composites.
Influence of Service Time on the Microstructure and High Temperature Mechanical Properties of T23 Boiler Tube
Authors: He Cheng , Shi Bao Liang , Li Wen Sheng , Zhao Jian Ping , Xu Kai , Liu Yang , Ren Ai , Li Yan
Published: June 2017

The influence of long time service on the microstructure and high temperature mechanical properties of T23 steel was studied by optical microscopy, scanning electron microscopy, transmission electron microscopy and tensile testing machine. Results showed that lathy bainite ferrite disappears with the increasing service time, both the size and number of the carbides increases, and M23C6 carbides transform into M6C carbides rich in W element. The service process also has a significant influence on the recovery. Sub-grains were found at the grain boundaries with little dislocations in the matrix after 27448 h service time. After running for 27448 h the microstructure degradation of T23 steel is serious. High temperature tensile properties of T23 are closely related to the alloy aging degree. The reasons for the decrease of high temperature mechanical properties after long time service included microstructure degradations such as the increase of both the size and quantity of M23C6 carbides, the transformation of M23C6 to M6C, the desolution of Cr,W,and Mo elements, the decrease of the dislocation density and the occurrence of the sub-grains.
Critical Crack Tip Opening Displacement for X70 and X80 Steels - A Parametric Study
Authors: Liu Xiao Ben , Duan Qing Quan , Wang Bao Dong , Zhang Hong
Published: June 2017

High strength line-pipe steels are widely used in long distance gas pipelines. Fracture toughness is one major parameter in the performance evaluation of these line-pipe steels. For high strength line-pipe steels, critical crack tip opening displacement (CTOD) is one typical quantity for fracture toughness. In this paper, a series of experimental studies were conducted to investigate the influences of steel property and specimen thickness on critical CTOD by three points bending tests for X70 and X80 line-pipe steel. Results showed that the critical CTOD is mainly depended on the plastic crack mouth opening displacement of the specimen. For the same size specimens, the critical CTOD of X80 steel was much less than X70 steel. The specimen thickness had a significant influence on the plastic crack mouth opening displacement. With the decrease of the specimen thickness, the critical CTOD increased.
Fatigue Crack Growth Rate of High Strength Pipe Steels
Authors: Wu Kai , Zhang Hong , Xia Meng Ying , Wu Jing Tian , Liu Xiao Ben
Published: June 2017

Fatigue crack growth rate is a significant mechanical property of high strength pipe. Some properties of fatigue crack propagation can be obtained by evaluating the mechanical performance of the material. In this study experiment studies were conducted with the fatigue crack growth rate test for two commonly used high strength pipe steels, X70 and X80 pipe steels, and the relationships between the length of the crack (a) and the number of the loading cycles (N) were derived. In addition, the crack tip opening displacement Δδ was calculated. Based on the experimental results, a regression equation was fitted for da/dN and Δδ. Results showed that the regression equation is similar to the Paris Formula, and X80 pipe steel has lower crack growth rate than the X70 pipe steel.
The Microstructure Stability of Super304H Steel Aging at 750°C
Authors: Gu Bao Lan , Dong Jian Xin , Xu Tong
Published: June 2017

The microstructure stability and the effect of microstructure evolution on the properties of Super304H steel aged at 750°C for different time were investigated. The results showed that the microstructure of the Super304H steel after aging at 750°C consists of primary matrix and large amount of precipitated phases. The main precipitates were Cu-rich phase, MX phase and M23C6 carbides in austenitic matrix during aging. The M23C6 carbides precipitate preferentially at grain boundaries, and then coarsening remarkably with increasing aging time. The MX phase was stable during the whole aging process. The Cu-rich particle is smaller than 10 nm at the initial aging stage, and then coarsen with increasing aging time. The strength and hardness increase obviously at the initial stage due to the interaction of Cu-rich phase, MX phase and M23C6 carbides precipitation strength, in which Cu-rich phase strengthen action is the dominant. Coarsening M23C6 carbides weaken the strength during aging.
Effect of Steel Properties on Buckling Pressure of Corroded Pipelines
Authors: Li Meng , Zhang Hong , Xia Meng Ying , Wu Kai , Wu Jing Tian , Liu Xiao Ben
Published: June 2017

Due to the harsh environment for submarine pipelines, corrosion damage of the pipeline steels is inevitable. After the corrosion damage, pipelines are prone to failure and may cause serious consequences. The analysis of the effects of different steel properties on the collapse pressure of pipelines with corrosion defects is of importance for the option of appropriate pipeline and avoiding accidents. Based on the finite element method, the finite element model of the pipeline with defects under external pressure was built. Firstly, the accuracy of the numerical model was validated by comparing with previous experimental results. The effects of yield strength and strain hardening exponent on collapse pressure of pipelines with different sizes of defect were discussed in detail. Results showed that the yield strength and strain hardening exponent have different influences on collapse pressure: the collapse pressure increases with the increasing yield strength, and the collapse pressure decreases with the increasing strain hardening exponent.
The Effect of Twice Thermal Cycle on the Microstructure and Mechanical Properties of Coarse Grain Region in X80 Pipeline Steel
Authors: Li Shuo , Guo Xiao Jiang , Li Ye Zheng , Sui Yong Li , You Zong Bin
Published: June 2017

Based on the multi-pass welding characteristics of X80 pipeline steel, the influence of twice thermal cycle on the microstructure and mechanical properties of coarse grain region in X80 pipeline steel was investigated. The thermal cycles of weld coarse grain region with different peak temperature for the second thermal cycle were simulated with the Gleeble-3500 thermal/mechanical simulator. The Charpy impact absorbed energy for toughness was measured, and the corresponding optical micrographs and electron micrographs were systematically investigated to study the effect of the peak temperature on microstructure and impact toughness in the coarse grain region. The results of simulated experiment showed that the microstructure in heat affected zone of coarse grain region is granular bainitic and bainitic ferrite. When the peak temperature of the second thermal cycle is 800°C, the types of microstructure and the grain size of original austenite have no change. However, it forms network microstructure with chain structure in grain boundary and the reduction of toughness may be affected by the M–A constituents. With the peak temperature of 1000°C, the micro structure is composed of granular bainitic and a little bainitic ferrite. In this case, the grain size of austenite can be significantly fined, being helpful to increase the impact toughness.
Hot Ductility of 20Cr13 Steel at High Temperature
Authors: Zhao Fan , Zhou Ning Bo , Liu Guang Lei , Wang Zhi Lin , Liu Ya Zheng
Published: June 2017

Hot ductility of 20Cr13 steel at high temperature was investigated through tensile test. The main phases of the steel in temperature range of 600-1400 °C were calculated with thermodynamic software. The fracture morphologies and microstructure were observed by scanning electron microscopy. The steel showed good hot ductility in temperature range of 1000-1200 °C, and the area reduction was 82 % or more. In temperature range of 800-950 °C, the M23C6 precipitated at the grain boundary of austenite, and it fractured in the tensile process. Thus the micro-crack or micro-hole formed at the grain boundary of austenite, and the area reduction was 52-68 %. The ferrite precipitated at 800 or 1250 °C, and the micro-voids formed at interface of ferrite and austenite because of the discordant deformation of two phases, which was harmful to hot ductility. Moreover, quasi-cleavage fracture happened at 800 °C because of the ferrite cleavage, which further decreased hot ductility of the steel.
Modeling the Precipitation Kinetics of Cementite in Bainite in 0.17% Carbon Steel
Authors: Yang Yong , Wang Bin , Wang Zhao Dong , Li Yan Mei , Wang Guo Dong , Misra R.D.K.
Published: June 2017

Nanoscale cementite can be obtained in 0.17% carbon steel during isothermal treatment at 500oC after ultra fast cooling (UFC) and thermo-mechanical treatment. The precipitation strengthening contribution to yield strength was more than 250 MPa, when the heat treatment time was less than 20 min. The carbon diffusion is impacted by Mn and Si, which are redistributed during the precipitation process. All the effects induced by substitutional elements can be manifested through the restricted carbon diffusion, which is equal to the carbon diffusion multiplied by adjustable parameters. Based on this, a kinetic model has been adapted to simulate the precipitation behaviors of cementite involving the evolution of the number density per unit volume, radius of cementite over time, and the evolution of carbon concentration in matrix. An excellent agreement in mean radius of particles between the predictions of the model and experimental observations was obtained. It was found that the nucleation period of cementite was very short and did not exceed 0.2 s, and there was an overlap between the nucleation period and the growth period, and the coarsening period began at about 1s. In the growth stage, the carbon concentration in the matrix dropped rapidly and the mean radius of particles increased quickly. In the coarsening stage, the carbon concentration remained unchanged and the number of particles per unit volume fell sharply.
Effects of Interstitial Nitrogen Atoms on Atomic Oxygen Adsorption on Fe (001) Surface from Ab Initio Calculations
Authors: Ye Fei , Wang Ya Kun , Xu Fei Fan , Tong Ke
Published: June 2017

The effects of interstitial nitrogen atoms on the adsorption of atomic oxygen on fcc Fe (001) surface have been studied using ab initio density functional theory calculations to understand the initial stage of oxidation on nitrogenous austenitic stainless steel. It has been found out that the N atoms can improve the adsorption ability of the O atom at the hollow site on the surface, and thus promote the rapid passivation of nitrogenous austenitic stainless steel. This improvement is possibly because the Coulombic interactions between the O atom and the neighboring Fe and Cr atoms are enhanced due to the electron transfer from the Fe and Cr atoms to the N atoms.
Comparison of Residual Stress Measured by Diffraction Method and Matrix Etching Method in SiC Fiber Reinforced Titanium Matrix Composites
Authors: Wen Mao , Huang Hao , Li Hu , Wu Ming , Hu Chao Quan , Zhang Kan , Zheng Wei Tao
Published: June 2017

Measurement and modeling of residual stresses in SiC fiber reinforced titanium matrix composites (SiCf/Ti) are still a challenge. Diffraction method and matrix etching method can characterize the strains of matrix and fiber, respectively. A In this work, SiCf/Ti samples with perpendicular and parallel cross-sections to the fibers have been fabricated, and the residual stresses were measured by X-ray diffraction and matrix etching. The results showed that the axial matrix stress in sample with perpendicular cross-sections to the fibers was larger than that in sample with parallel cross-sections to the fibers, while the axial matrix stress calculated from etching was consistent with that from X-ray diffractions based on triaxle stress model, confirming the reliability of triaxle stress model.
Analyzing Hysteresis and Thermal Expansion Coefficient of M40/AZ91D during Thermal Cycling
Authors: Song Mei Hui , Zhang Yu , Li Yan Chun , Chen Guo Qin , Xiu Zi Yang
Published: June 2017

In this work, AZ91D composite reinforced with M40 fiber was prepared by pressure impregnation method. Expansion behaviors of M40/AZ91D composite were studied with thermal expansion instrument in 25-150 °C and 25-150 °C temperature ranges of internal heat circulation, and then analyzed the influence law of hysteresis, residual strain and coefficient of thermal expansion (CTE) by different temperature change rate. The results revealed that residual stress and strain in process of pressure impregnation would lead to strain hysteresis and residual strain of composite in thermal cycling. At the same time, the CTE of the composites decreased with the increase of cycle times. Residual strain of the composite went up with the rise of temperature changed rate of the thermal cycling and CTE decreased with temperature change rate ascending in the 25-150°C temperature range. The CTE of the composites decreased with the increase of temperature during the heating process, which cut down with the increase of temperature in process of heating and cooling in the 25-495°C temperature range.
Effect of Rare-Earth Element Y on the Microstructure and Mechanical Properties of the Mg-6.0wt.%Zn-0.5wt.%Zr Alloy
Authors: Liu Yu , Zhou Ji Xue , Liu Yun Teng , Tang Shou Qiu
Published: June 2017

The extruded Mg-6.0wt.%Zn-0.5wt.%Zr (ZK60) alloys with 0.5wt.% and 1.0wt.% Y additions were prepared. The microstructures and tensile properties of the alloys aged in different conditions were investigated. The results show that the specimen with 1.0wt.% Y additions and aged at 453K for 15 h had the best tensile strength. The ultimate tensile strength and yield strength reached 365MPa and 352MPa, respectively. The grain refinement, the formation of the fine dispersed Mg-Zn particles and the W-Mg3Zn3Y2 ternary phase may be the main reasons for the improvement. The average grain size reached to ~ 3μm. The size of the fine and dispersed particles was only several nanometers and the particle number density (Nv) was very high. The crystallographic characteristics of the ternary W-Mg3Zn3Y2 phase were studied by the transmission electron microscope and selected area electron diffraction techniques. The crystallographic orientation relationship between the W phase and the α-Mg matrix is identified as: [2 0]α//[ ]w, (0002)α plane near parallel to the (220)w plane with a 3.5 degree angle difference. This orientation relationship has rarely been studied and reported.
Morphology of Intermetallic Compound and Interface Bonding State in Pure Al/Steel Clad Plates after 645°C/1h Diffusion Annealing
Authors: Gao Kun Yuan , Yan Xiao Lei , Ding Yu Sheng , Wen Sheng Ping , Huang Hui , Wu Xiao Lan , Yang Qian , Nie Zuo-Ren
Published: June 2017

The correlation between intermetallic compound (IMC) and interface bonding state of the pure Al/08Al steel clad plate after 645°C/1h diffusion annealing was studied using the SEM. The results indicated that after 645°C/1h diffusion annealing for the pure Al/08Al steel clad plate, the IMC grew continuously along the interface with the thickness of 2-6 μm, while, at some regions grew abnormally with the thickness up to 10-30 μm. Moreover, some intrinsic defects at the interface, such as voids in the abnormally grown IMC and micro cracks along the interface were observed. The voids were possibly caused by huge difference of Al and Fe in diffusion coefficient, which is known as Kirkendall effect. On the other hand, the micro cracks could be attributed to the thermal stress during the cooling process because of larger difference of thermal expansion rate between Al and Al-Fe IMC. The intrinsic defects at the interface of Al/Steel could supply a novel way to correlate the morphology of IMC and interface bonding strength.
Effect of Si Content of Matrix Alloy on the Microstructure and Properties of Sip/Al-Si-Mg Composites Prepared by Pressure Infiltration Method
Authors: Liang Jiao Yan , Hou Xue Wei
Published: June 2017

Si particles reinforced Al matrix composites (Sip/Al) have been widely used in the electronic packaging filed, and the higher mechanical and themo-physical properties are required for their application. In the present work, the effect of Si content (from 0.28 to 6.95 wt. %) in the matrix alloy on the microstructure, mechanical and thermo-physical properties of Sip/Al-Si-Mg composites have been investigated. Sip/Al-Si-Mg composites with 55 vol. % Si particles were prepared by pressure infiltration method. It has been found that the increment of Si content led to the improvement of relative density of composites. Moreover, the bending strength and thermal conductivity of Sip/Al-Si-Mg composites reached its maximum at Si content of 1.98 wt.%, which were 238.8MPa and 159.5W/(m∙K), respectively. Furthermore, the coefficient of thermal expansion (CTE) of Sip/Al-Si-Mg composites decreased with the increase of Si content. The mechanism of Si content on the microstructure of performance of Sip/Al-Si-Mg composites has been discussed.
Albumin Cobalt Binding or Ischaemia Modified Albumin: A test of great prognostic value in malaria
Authors: Ghosh Kinjalka , Muddeshwar M G , Lokhande Monoj , Ghosh Kanjaksha
Published: June 2017

Background :  We evaluated albumin cobalt binding (ACB) assay as a prognostic marker for severe malaria  in a medical college setting .Methods :Consecutive adult patients admitted with both vivax and falciparum malaria were evaluated with ACB assay at the time of admission. Detailed work up and individual patient directed management were instituted in addition to immediate artemisin based antimalarial therapy.Results :100 consecutive patient ( 50 with vivax and 50 with falciparum malaria ) were evaluated . Reference range for ACB assay was established using 50 adult healthy ( 25 male and 25 female ) individuals . 16 out of 50 p. falciparum infected developed complicated malaria. All malaria infected patients had high ACB levels ( P<0.0001). There was step wise increase in ACB levels from healthy volunteers to different category of malaria( P<0.0001 ) without any overlap.  Conclusion: ACB can be used as a robust simple and cheap prognostic marker for organ dysfunction in  severe malaria.
Evaluation of accuracy of shade selection using two spectrophotometer systems: Vita Easyshade and Degudent Shadepilot
Authors: Kalantari Mohammad Hassan , Ghoraishian Seyed Ahmad , Mohaghegh Mina
Published: June 2017

Objective: The aim of this In vitro study was to evaluate the accuracy of shade matching using two spectrophotometric devices. Materials and Methods: Thirteen patients who require a full coverage restoration for one of their maxillary central incisors were selected while the adjacent central incisor was intact. 3 same frameworks were constructed for each tooth using computer-aided design and computer-aided manufacturing technology. Shade matching was performed using Vita Easyshade spectrophotometer, Shadepilot spectrophotometer, and Vitapan classical shade guide for the first, second, and third crown subsequently. After application, firing, and glazing of the porcelain, the color was evaluated and scored by five inspectors. Results: Both spectrophotometric systems showed significantly better results than visual method (P < 0.05) while there were no significant differences between Vita Easyshade and Shadepilot spectrophotometers (P < 0.05). Conclusion: Spectrophotometers are a good substitute for visual color selection methods.
Anterosuperior rehabilitation with metal-free fixed prosthesis based on zirconia
Authors: Cenci Sthelen Nayara , Gontarsky Igor Alessandro , Moro Marcella Goetz , Pinheiro Lidia Olga Bach , Bührer Samra Adriana Postiglione
Published: June 2017

The loss of upper front dental elements causes functional and psychosocial problems to the affected individuals. In this case report, the treatment planning considered hard and soft tissue loss for a complex fixed partial denture (FPD) rehabilitation. The six-element, all-ceramic FPD was manufactured using a computer-aided design/computer-aided manufacturing system with zirconia framework, veneered with leucite-reinforced ceramic. Ceramic artificial gum was also produced to guarantee tooth-facial proportions as well as lip support, promoting both esthetics and phonetics. The material's mechanical properties allowed for the coupling of the esthetic and mechanical requirements, proving an alternative to the well-established metal-ceramic technology, optimizing biomimetic. One of the endodontic-treated abutment teeth required a radicular retainer with cast metal post, but because of the opacity of zirconia, the esthetics of the prosthesis was not compromised. The low silica content of high resistance ceramics such as zirconia hampers the adhesive cementation, with numerous studies advocating for different cementation protocols, with no clear scientific consensus so far. In the present case, the internal surface of the FPD was initially blasted with aluminum oxide, followed by the application of a universal adhesive system containing 10-methacryloyloxydecyl dihydrogen phosphate. Finally, cementation to the dental structure was conducted with dual-cure self-adhesive resin cement.
Dental treatment considerations for a pediatric patient with incontinentia pigmenti (Bloch-Sulzberger syndrome)
Authors: Chen Amy Yi-Cheng , Chen Kevin
Published: June 2017

Incontinentia pigmenti (IP) is a uncommon gene disorder, heritage with X-linked dominant mode. IP patients have a characteristic dentition varying from marked hypodontia to delayed eruption and conical crowns on both dentitions. A 5½-year-old girl, whose mother and younger sister were also diagnosed with IP, has the whirling-like pigmented skin lesion over her trunk and four extremities. Four primary teeth and multiple permanent tooth germs were found to be congenital missing. Dental considerations of further treatment were discussed with her parents including the preservation of primary molars, possible interim prosthesis in mixed or permanent dentition, full mouth rehabilitation with orthodontic and prosthodontic combined treatment, and implant therapy in adulthood. Early and longitudinal involvement of pediatric dentist to deal with the dental complications of IP can not only solve the esthetic problem and oral function but also maintain the oral health of children with IP to adulthood.
Локальные предельные теоремы для одного класса распределений вероятностной комбинаторики
Authors: Timashev Aleksandr Nikolaevich
Published: June 2017

Рассматривается функция $f(z)$, разлагающаяся в степенной ряд с неотрицательными коэффициентами, сходящийся в круге положительного радиуса $R.$ Пусть при $|z|<R$ случайная величина $\xi_n$, $n=1,2,\ldots$, имеет распределение $$P\{\xi_n=N\}=\frac{\mathrm{coeff}_{z^n}(\frac{(f(z))^N}{N!})}{\mathrm{coeff}_{z^n}(\exp(f(z)))}, N=0,1,\ldots$$ (если знаменатель дроби положителен). Приводятся примеры использования таких распределений в вероятностной комбинаторике. Доказаны локальные нормальные теоремы для распределения $\xi_n$ в двух случаях: когда при $|z|<1$ $$f(z)=(1-z)^{-\lambda}, \lambda=\mathrm{const}\in(0,1],$$ а также при условии, что множество $A$ номеров положительных коэффициентов разложения $f(z)$ в степенной ряд имеет вид $$A=\{m^r / m\in\mathbb N\}, r=\mathrm{const}\in\mathbb N, r\ge2$$ (сами эти коэффициенты считаются равными 1). В качестве гипотезы сформулирована общая локальная нормальная теорема для случайных величин $\xi_n.$ Указаны случаи, когда утверждение этой теоремы оказывается справедливым.
Биортогональные вейвлет-коды с заданным кодовым расстоянием
Authors: Soloviev Alexander Artemovich , Chernikov Dmitry Vladimirovich
Published: June 2017

Предложена схема построения 2-циркулянтных кодов c заданным кодовым расстоянием на основе биортогональных фильтров со свойством точного восстановления над конечным полем нечетной характеристики. Приведенный алгоритм построения биортогональных фильтров использует алгоритм Евклида нахождения НОД многочленов.
Disseminating Innovations in Teaching Value-Based Care Through an Online Learning Network
Authors: Gupta Reshma , Shah Neel T. , Moriates Christopher , Wallingford September , Arora Vineet M.
Published: June 2017

Background 

A national imperative to provide value-based care requires new strategies to teach clinicians about high-value care.

Objective 

We developed a virtual online learning network aimed at disseminating emerging strategies in teaching value-based care.

Methods 

The online Teaching Value in Health Care Learning Network includes monthly webinars that feature selected innovators, online discussion forums, and a repository for sharing tools. The learning network comprises clinician-educators and health system leaders across North America. We conducted a cross-sectional online survey of all webinar presenters and the active members of the network, and we assessed program feasibility.

Results 

Six months after the program launched, there were 277 learning community members in 22 US states. Of the 74 active members, 50 (68%) completed the evaluation. Active members represented independently practicing physicians and trainees in 7 specialties, nurses, educators, and health system leaders. Nearly all speakers reported that the learning network provided them with a unique opportunity to connect with a different audience and achieve greater recognition for their work. Of the members who were active in the learning network, most reported that strategies gleaned from the network were helpful, and some adopted or adapted these innovations at their home institutions. One year after the program launched, the learning network had grown to 364 total members.

Conclusions 

The learning network helped participants share and implement innovations to promote high-value care. The model can help disseminate innovations in emerging areas of health care transformation, and is sustainable without ongoing support after a period of start-up funding.
OzFlux data: network integration from collection to curation
Authors: Isaac Peter , Cleverly James , McHugh Ian , van Gorsel Eva , Ewenz Cacilia , Beringer Jason
Published: June 2017

Abstract. Measurement of the exchange of energy and mass between the surface and the atmospheric boundary-layer by the eddy covariance technique has undergone great change in the last 2 decades. Early studies of these exchanges were confined to brief field campaigns in carefully controlled conditions followed by months of data analysis. Current practice is to run tower-based eddy covariance systems continuously over several years due to the need for continuous monitoring as part of a global effort to develop local-, regional-, continental- and global-scale budgets of carbon, water and energy. Efficient methods of processing the increased quantities of data are needed to maximise the time available for analysis and interpretation. Standardised methods are needed to remove differences in data processing as possible contributors to observed spatial variability. Furthermore, public availability of these data sets assists with undertaking global research efforts. The OzFlux data path has been developed (i) to provide a standard set of quality control and post-processing tools across the network, thereby facilitating inter-site integration and spatial comparisons; (ii) to increase the time available to researchers for analysis and interpretation by reducing the time spent collecting and processing data; (iii) to propagate both data and metadata to the final product; and (iv) to facilitate the use of the OzFlux data by adopting a standard file format and making the data available from web-based portals. Discovery of the OzFlux data set is facilitated through incorporation in FLUXNET data syntheses and the publication of collection metadata via the RIF-CS format. This paper serves two purposes. The first is to describe the data sets, along with their quality control and post-processing, for the other papers of this Special Issue. The second is to provide an example of one solution to the data collection and curation challenges that are encountered by similar flux tower networks worldwide.
Hydration Status and Diurnal Trophic Interactions Shape Microbial Community Function in Desert Biocrusts
Authors: Kim Minsu , Or Dani
Published: June 2017

Abstract. Biological soil crusts (biocrusts) are self-organised thin assemblies of microbes, lichens and mosses ubiquitous in arid regions serving as important ecological and biogeochemical hotspots. Biocrust ecological function is intricately shaped by strong gradients of water, light, oxygen and dynamics in abundance and spatial organisation of the microbial community within a few millimetres of the soil surface. We report a mechanistic model that links biophysical and chemical processes that shape the functioning of biocrust representative microbial community that interacts trophically and responds dynamically to cycles of hydration, light, and temperature. The model captures key features of observed microbial activity and distribution (during early stages of biocrust establishment) and associated dynamics of biogeochemical fluxes. The study offers new insights into the highly dynamic and localised processes that shape biocrust functioning and elude quantification based on averaged representation of such delicate and globally important ecological assembly.
Volcanic stratospheric sulphur injections and aerosol optical depth
from 500 BCE to 1900 CE
Authors: Toohey Matthew , Sigl Michael
Published: June 2017

Abstract. The injection of sulphur into the stratosphere by explosive volcanic eruptions is the cause of significant climate variability. Based on sulphate records from a suite of ice cores from Greenland and Antarctica, the eVolv2k database includes estimates of the magnitudes and approximate source latitudes of major volcanic stratospheric sulphur injection (VSSI) events from 500 BCE to 1900 CE, constituting an update of prior reconstructions and an extension of the record by 1000 years. The VSSI estimates incorporate improvements to the ice core records in terms of synchronization and dating, refinements to the methods used to estimate VSSI from ice core records, and includes first estimates of the random uncertainties in VSSI values. VSSI estimates for many of the largest eruptions, including Samalas (1257), Tambora (1815) and Laki (1783) are within 10% of prior estimates. A number of strong events are included in eVolv2k which are largely underestimated or not included in earlier VSSI reconstructions, including events in 540, 574, 682 and 1108 CE. The long term annual mean VSSI from major volcanic eruptions is estimated to be ∼ 0.5 Tg [S] yr−1, ∼ 50 % greater than a prior reconstruction, due to the identification of more events and an increase in the magnitude of many intermediate events. A long-term, latitudinally and monthly resolved stratospheric aerosol optical depth (SAOD) time series is reconstructed from the eVolv2k VSSI estimates, and the resulting global mean SAOD is found to be similar (within 33%) to a prior reconstruction for most of the largest eruptions. The long-term (500 BCE–900 CE) average global mean SAOD estimated from the eVolv2k VSSI estimates and including a constant "background" injection of stratospheric sulphur is ∼ 0.014, 30 % greater than a prior reconstruction. These new long-term reconstructions of past VSSI and SAOD variability give context to recent volcanic forcing, suggesting that the 20th century was a period of somewhat weaker than average volcanic forcing, with current best estimates of 20th century mean VSSI and SAOD values being 25 and 14 % less, respectively, than the mean of the 500 BCE to 1900 CE period. The reconstructed VSSI and SAOD data are available at https://doi.org/10.1594/WDCC/eVolv2k_v2>.
Moving beyond the cost–loss ratio: economic assessment of streamflow forecasts for a risk-averse decision maker
Authors: Matte Simon , Boucher Marie-Amélie , Boucher Vincent , Fortier Filion Thomas-Charles
Published: June 2017

Abstract. A large effort has been made over the past 10 years to promote the operational use of probabilistic or ensemble streamflow forecasts. Numerous studies have shown that ensemble forecasts are of higher quality than deterministic ones. Many studies also conclude that decisions based on ensemble rather than deterministic forecasts lead to better decisions in the context of flood mitigation. Hence, it is believed that ensemble forecasts possess a greater economic and social value for both decision makers and the general population. However, the vast majority of, if not all, existing hydro-economic studies rely on a cost–loss ratio framework that assumes a risk-neutral decision maker. To overcome this important flaw, this study borrows from economics and evaluates the economic value of early warning flood systems using the well-known Constant Absolute Risk Aversion (CARA) utility function, which explicitly accounts for the level of risk aversion of the decision maker. This new framework allows for the full exploitation of the information related to a forecasts' uncertainty, making it especially suited for the economic assessment of ensemble or probabilistic forecasts. Rather than comparing deterministic and ensemble forecasts, this study focuses on comparing different types of ensemble forecasts. There are multiple ways of assessing and representing forecast uncertainty. Consequently, there exist many different means of building an ensemble forecasting system for future streamflow. One such possibility is to dress deterministic forecasts using the statistics of past error forecasts. Such dressing methods are popular among operational agencies because of their simplicity and intuitiveness. Another approach is the use of ensemble meteorological forecasts for precipitation and temperature, which are then provided as inputs to one or many hydrological model(s). In this study, three concurrent ensemble streamflow forecasting systems are compared: simple statistically dressed deterministic forecasts, forecasts based on meteorological ensembles, and a variant of the latter that also includes an estimation of state variable uncertainty. This comparison takes place for the Montmorency River, a small flood-prone watershed in southern central Quebec, Canada. The assessment of forecasts is performed for lead times of 1 to 5 days, both in terms of forecasts' quality (relative to the corresponding record of observations) and in terms of economic value, using the new proposed framework based on the CARA utility function. It is found that the economic value of a forecast for a risk-averse decision maker is closely linked to the forecast reliability in predicting the upper tail of the streamflow distribution. Hence, post-processing forecasts to avoid over-forecasting could help improve both the quality and the value of forecasts.
On the resonance hypothesis of storm surge and surf beat run-up
Authors: Postacioglu Nazmi , Özeren M. Sinan , Canlı Umut
Published: June 2017

Abstract. Resonance has recently been proposed as the fundamental underlying mechanism that shapes the amplification in coastal run-up for storm surges and surf beats, which are long-wavelength disturbances created by fluid velocity differences between the wave groups and the regions outside the wave groups. It is without doubt that the resonance plays a role in run-up phenomena of various kinds; however, we think that the extent to which it plays its role has not been completely understood. For incident waves, which we assume to be linear, the best approach to investigate the role played by the resonance would be to calculate the normal modes by taking radiation damping into account and then testing how those modes are excited by the incident waves. Such modes diverge offshore, but they can still be used to calculate the run-up. There are a small number of previous works that attempt to calculate the resonant frequencies, but they do not relate the amplitudes of the normal modes to those of the incident wave. This is because, by not including radiation damping, they automatically induce a resonance that leads to infinite amplitudes, thus preventing them from predicting the exact contribution of the resonance to coastal run-up. In this study we consider two different coastal geometries: an infinitely wide beach with a constant slope connecting to a flat-bottomed deep ocean and a bay with sloping bottom, again, connected to a deep ocean. For the fully 1-D problem we find significant resonance if the bathymetric discontinuity is large.The linearisation of the seaward boundary condition leads to slightly smaller run-ups. For the 2-D ocean case the analysis shows that the wave confinement is very effective when the bay is narrow. The bay aspect ratio is the determining factor for the radiation damping. One reason why we include a bathymetric discontinuity is to mimic some natural settings where bays and gulfs may lead to abrupt depth gradients such as the Tokyo Bay. The other reason is, as mentioned above, to test the role played by the depth discontinuity for resonance.
Detection of collapsed buildings due to the 2016 Kumamoto, Japan, earthquake from Lidar data
Authors: Moya Luis , Yamazaki Fumio , Liu Wen , Yamada Masumi
Published: June 2017

Abstract. The 2016 Kumamoto earthquake sequence was triggered by an Mw 6.2 event at 21:26 on April 14. Approximately 28 hours later, at 1:25 on April 16, an Mw 7.0 event (the mainshock) followed. The epicenters of both events were located 10 near the residential area of Mashiki town and the region nearby. Due to very strong seismic ground motion, the earthquake produced extensive damage to buildings and infrastructure. In this paper, collapsed buildings were detected using a pair of digital surface models (DSMs), taken before and after the April 16 mainshock by airborne light detection and ranging (Lidar) flights. Different methods for extracting the collapsed buildings from the data were evaluated, and the change of average elevations within a building footprint was found to be the most important feature. Finally, the distribution of collapsed 15 buildings in the study area was presented, and the result was consistent with that of a building damage survey performed after the earthquake.