bluuebunny/crossref_metadata_2025 huggingface dataset:
Fatigue Monitoring of Double Surface Defects Using PZT Based Electromechanical Impedance and Digital Image Correlation Methods
Authors: Annamdas Venu Gopal Madhav , Pang John Hock Lye , Chew You Xiang , Hoh Hsin Jen , Zhou Kun , Song Bin
Published: March 2014

Most of the engineering failures especially in mechanical and aerospace industry are due to the fatigue. Fatigue cracks and their propagation can be monitored by observing changes in the structural stiffness resulting from strength reduction as a function of the number of loading cycles. This monitoring can be observed using piezoceramic (PZT) transducer based electromechanical impedance (EMI) technique, and digital image correlation (DIC) system which uses variations on structural surface. The fatigue load usually aggravates the fracture if any defects pre-exist in the structure. The present work monitors multiple-crack emanating from electrode sparked multiple plane defects which are induced in to the specimens prior to the fatigue test, using EMI technique and DIC system. The fracture occurs much below the ultimate stress for the structures which already have defects as in the present case. EMI technique uses signature comparison of healthy and cracked state of the structure to depict crack growth. Initial detection of surface hair-line cracks from the corners of induced defects and their propagation till merging and subsequent failure were explained by signature variations and DIC techniques. Thus, a signal processing technique EMI, and image processing technology DIC were found to complement each other in prediction of early crack and their appearance on surface of the specimens.
Development of Low Temperature Nitriding Process and its Effects on the 4-Points Bending Fatigue Properties of Commercially Pure Titanium
Authors: Kikuchi Shoichi , Nakamura Yuta , Ueno Akira , Ameyama Kei
Published: March 2014

In order to improve both of the fatigue and tribological properties of commercially pure (CP) titanium, a low temperature nitriding process was developed. Cold rolling was introduced as pre-treatment of plasma nitriding to create fine grains which could accelerate the diffusion of nitrogen into the material. Surface microstructures of the nitrided specimens pre-treated with cold rolling were characterized using a micro-Vickers hardness tester, an optical microscope, a scanning electron microscope (SEM), X-ray diffraction (XRD) and electron backscatter diffraction technique (EBSD). Titanium-nitrides (TiN and Ti2N) were formed on the surface nitrided at the temperature greater than 600 °C. Moreover, thicker compound layer was formed in the nitrided CP titanium pre-treated with cold rolling in comparison to the only nitrided one, resulting in showing higher hardness. 4-points bending fatigue tests were performed for the specimens treated with low temperature nitriding (600 °C), which could suppress the grain-coarsening, under the stress ratio R = 0.1 at room temperature. In addition, fatigue fracture mechanism of nitrided CP titanium was discussed based on the observations of microstructure and fracture surface.
Influence of Shot Peening on the Fatigue Strength of Custom 465 Stainless Steel for Aeronautic Application
Authors: Bonora Rafael Gustavo , Voorwald Herman Jacobus Cornelis , Cioffi Maria Odila Hilário
Published: March 2014

This project was originated from the national aircraft industry requirements to reduce the use of coated materials with electroplated chromium or cadmium that produce waste, which is harmful to health or the environment. The selected material is a Custom 465 stainless steel used in the aeronautical field due to its high mechanical strength. Considering the load sustained by the wheel axis of the landing gear, the Custom 465 is tested in axial fatigue. The objective is to compare the behavior of the Custom 465 with plated AISI 4340 steel coated with cadmium. X-ray diffraction method was used to determine the residual stress field induced by shot peening.
Case Studies of Fatigue Failures in Defence Aircraft Components
Authors: Smith Cathy , Donnelly Drew
Published: March 2014

Components and systems of military aircraft are regularly subjected to severe operating conditions, which lead to the development of a wide range of failure modes. The Defence Science and Technology Organisations (DSTO) Forensic Engineering and Accident Investigation group investigates such failures for the Australian Defence Force (ADF). Correct diagnosis of these failures has provided the ADF with immediate advice that has contributed to increased aircraft safety, improved operational availability, and significant cost savings. This paper presents a number of case studies of recent fatigue failures which have occurred in Australian Defence aircraft. The case studies include examples of failures which occurred via differing fatigue initiating and driving mechanisms. Details of the forensic investigations relating to each case study are provided and the ensuing remedial actions discussed.
Stabilization of Raw Earth through Alkaline Activation
Authors: Santos de Oliveira Leandro , Barbosa Normando Perazzo , Santos Fabiana Silva , de Carvalho Carlos Maviael
Published: March 2014

Stabilization is important in earthen construction in order to improve mechanical strength, volumetric stability, workability and even ductility. Currently, the products used to stabilize the earth are lime, Portland cement and bitumen emulsions. Due to the environmental problems that the mankind faces nowadays, the use of earthen construction is increasing. Adobe is the most traditional type of block used in masonry. To improve strength against water, a new way to stabilize this kind of unburned earth block is proposed by the alkaline activation of earth. This paper presents the first results about the experimentation made in the stabilization of soil with alkali activator. Two cure temperatures were tested: room temperature and oven at 50°C. The amounts of stabilizer used were 3% and 6% activator by mass of earth. Results show that it is possible for adobe blocks to be resistant to water action using the alkaline activation.
Effect of Recycled Concrete Aggregates and Natural Pozzolana on Rheology of Self-Compacting Concrete
Authors: Kenai Said , Menadi Belkacem , Debbih Amina , Kadri El Hadj
Published: March 2014

Self-compacting concrete (SCC) is a very fluid concrete in which its compaction can take place under the effect of its own weight, without vibration. SCC is characterized by its high volume of paste, and the use of superplasticizers. Very little work is reported in the literature on the use of recycled aggregates in SCC. The main objective of this paper is to study the effect of coarse and fine recycled concrete aggregates on the fresh properties of SCC, by substitution of either 100% or 50% of natural aggregates by recycled aggregates. The effect of substitution of 15% by weight of cement of natural pozzolana on the fresh properties of SCC is also studied. The results have shown that the substitution of 50% or 100% of natural aggregates by recycled concrete aggregates gives SCC with very comparable rheological properties to that of the reference SCC. However, SCC with recycled aggregates are less stable against bleeding. The addition of natural pozzolana decreases workability for both SCC with natural aggregates or with recycled aggregates.
Thermal, Moisture and Energy Performance of a Hempcrete Test Structure in the Northern Prairie Climate of Manitoba, Canada
Authors: Dick Kris J. , Pinkos Jeremy
Published: March 2014

The processing of industrial hemp, cannabis sativa, results in three basic constituents seed, fibre, and hurd. Within Manitoba the main focus is with seed and oil products. When considering the entire plant approximately 60-70% is the predominantly cellulose woody core called the hurd. A combination of hemp hurd, a binder and water in various proportions is used in the construction of buildings referred to as hempcrete. Hempcrete is used as an environmental barrier providing resistance to heat transfer and to manage moisture of the building envelope. Engineering and architectural designers practicing in the field of non-conventional material applications have clearly indicated a need for design data.
This paper presents a portion of research data collected over the past 18 months from a 23.8 m2 (256 ft2) test building on the campus of the University of Manitoba at the Alternative Village. The design temperatures for this location range from-35°C to +32°C. The structure was built using 300 mm thick pre-fabricated hempcrete panels. In addition to indoor and exterior ambient conditions, the temperature is monitored at 40 locations within the envelope - at the interior, middle and exterior providing a profile through the wall system. Similarly, the relative humidity is monitored within the wall and used in conjunction with a sorption isotherm to estimate the moisture content within the assembly. The building is kept at a constant temperature during the heating season with the energy consumption monitored continuously. This building is one of several on the test site that are all identical in terms of size and configuration. This paper will provide a comparison between the thermal, moisture and energy performance of the hempcrete structure and a conventional wood frame, batt-insulated building that represents the vernacular construction in Manitoba.
Fatigue Calculation of a Car Component Subjected to Random Vibrations
Authors: Razvan Curtean , Lupea Iulian
Published: March 2014

In this article, a random vibration simulation approach applied to a car component is presented. The main vibration sources which appear in the automotive body are mentioned as input for random analysis. By using finite element analysis, one can estimate the response of the structure in terms of the probability of the maximum displacement and stress. The normal distribution function was used in the analysis for the statistical interpretation of the results. By using the random vibration simulation method, the response of a structure excited by random vibrations can be estimated, with a good precision for various applications. The resulted stress it is used to perform fatigue evaluation by using Palmgren Miner method.
Stress and Displacements Analysis for Drilling Mast Elements Made of Rectangular Pipe under the Action of the Wind as a Hurricane
Authors: Stanciu Lavinia Silvia , Popa Ioan
Published: March 2014

According to API 4F, SR EN ISO 14693:2004, the action of wind as a hurricane, with a speed of 120 km/h, represents a special load the drilling masts, which are a part of the drilling rigs, are submitted to. By their construction, the masts are multiple statically indetermined structures, made of many welded ends beams, and are designed as a component of the hoisting system, having some main purposes as supporting devices as the crown block at the top, the crane, the rotary swivel etc and providing support for the drill pipes to be stacked vertically during the round trips operations. In the present paper was analyzed, from this point of view, a drilling mast made of rectangular pipes, rated for a maximum hook load of 300 kN. The authors calculated the wind pressures, in accordance with the formulae specified in the standards, and introduced this special loading as a distributed load, firstly on the transversal direction of the mast and then on the longitudinal direction, with respect to the spatial reference system attached to the analyzed mast. Using the Finite Element Method, the nodes displacements and mast`s elements stress were determined. The most important obtained values of the displacements and stress were graphically shown and commented and, also, interesting conclusions are presented concerning the drilling mast resistance in specific conditions that occur in case of the wind action as a hurricane.
Stress Distribution in an Artificial Cruciate Ligament during the Gait Cycle
Authors: Bogdan Lucian , Nes Cristian Sorin , Enkelhardt Angelica , Faur Nicolae , Sticlaru Carmen , Pătraşcu Jenel Marian
Published: March 2014

This paper presents a finite element analysis in order to determinate the stress distribution in an proposed model of the artificial cruciate ligament of the knee joint during the gait cycle.
Stress State Evaluation in Complete Denture by Electrical Resistance Strain Gage
Authors: Cernescu Anghel , Faur Nicolae , Bortun Cristina
Published: March 2014

Total dentures are made of acrylic resins and artificial teeth. Among the prevalent fracture types of the dentures, 29% was a mid-line fracture, in which 68% were observed in maxillary complete dentures and 28% in mandibular complete dentures. Due to the large number of failures recorded on the maxillary dentures, several studies were conducted to establish the causes that produce these failures but also to find solutions for their prevention. One source of information about the strength of a maxillary denture under the applied load, is represented by the establishment of the stress and strain state during the loading. Different methods have been used for investigating the strain or stress distribution during deformation of dentures. The purpose of this paper is to evaluate the stress and strain state of a maxillary denture loaded in compression until the final fracture. For this study, electrical resistance strain gage were used for evaluation the strain and stress distribution in the maxillary denture made of different acrylic resins. Based on observations from practice, the strain gages were applied on the middle line of the denture at the base of the incisors and respectively on the sides of the denture, under molars. The dentures were loaded until failure and were registered the strains in the located strain gages. Also, for each type of acrylic resin were determined separately the mechanical properties of elasticity and strength. Based on the tests conducted were determined the critical stress and strain in the areas of interest. In all the tests carried out the fracture occurred in the median area of the denture and the crack was initiated between the incisor teeth. The stress and strain field associated with the crack initiation mode showed a strong influence of geometry on the fracture strength of denture. Also the type of acrylic resin has a significant effect on the fracture strength of complete denture either by strength capacity but especially by their ability to elasticity. Based on this analysis have been established new criteria for selection of acrylic resins, not only for aesthetic reasons but also for elasticity and strength reasons.
Mechanical and Dynamic Characteristics of Laminated Glass Sheets Used for Staircases
Authors: Ghindea Cristian Lucian , Cretu Dan , Cruciat Radu , Bogdan Ovidiu
Published: March 2014

In case of laminated glass strips, the mechanical characteristics of the composite element are different from the values that are obtained for the same element from a homogeneous and isotropic material. The experimental tests presented in the paper aims to determine the mechanical characteristics of laminated glass strips used to make a staircase. For the experiment, quasi-static and dynamic tests were conducted on different glass stair steps, made from normal and tempered glass, with different number and thicknesses glass sheets. The paper presents the carrying out conditions for the experiments, the synthesis of data processing and comments on the experimental results. Experimental test results led to the constructive solution of the glass staircase steps. For staircase building up, tempered glass was chosen and the values obtained for the mechanical properties, strength and deformation capacity of the system were used in its design. Whole set of experimental tests led to a successful design and build-up of the glass staircase.
Fatigue Response of the Hybrid Joints Obtained by Hot Spot Welding and Bonding Techniques
Authors: Sadowski Tomasz , Kneć Marcin , Golewski Przeymysław
Published: March 2014

Hybrid joining of structural parts (e.g. [3-1) is relatively new approach to create more safe and reliable connection of the critical part of engineering structures. In this paper we consider hybrid joint consisting of 2 aluminum stripes and an angle bar (e.g. [7]) joined by 2 simple techniques: hot spot welding (HSW) and adhesive bonding (AB). The samples were subjected to fatigue tests in order to find fatigue response at different level of load amplitude. New method of plastic deformation measurement during fatigue was proposed with application of Digital Image Correlation (DIC) method.
Numerical analysis of the hybrid joint fatigue response was proposed in the paper taking into account both: gradual degradation of the bonding layer and plastic damage in the aluminium strips due to cyclic loading.
Evaluation of the Thermally Sprayed Cermet Coatings Adhesion by Scratch Test
Authors: Uţu Ion Dragos , Şerban Viorel Aurel
Published: March 2014

The paper presents a study regarding the evaluation of the adherence strength using scratch test of WC 12%Co coating deposited by high velocity oxygen fuel (HVOF) method onto the surface of a carbon steel substrate.The coating morphology was characterized by scanning electron microscopy (SEM).The scratching process of the WC Co coating was controlled and monitored using a Millennium 200 Technical Tribo equipment, the test being performed according to DIN EN 1071-3 Standard. The load required to cause the failure of the WC Co coating on the carbon steel substrate was determined. The points where the coating fails by cracking are taken as critical failure points.
Mechanical Behaviour of Nickel Based Amorphous Alloys during Tensile Test at Different Strain Rates
Authors: Cornea Florin Marian , Codrean Cosmin , Buzdugan Dragoş , Şerban Viorel Aurel
Published: March 2014

Nickel based amorphous alloys have been developed in ribbons form by planar flow casting method and were subjected to tensile tests. For this purpose, specimens with calibrated area were obtained by electroerosion cutting method and tested at tensile test with different strain rates. Following the results obtained during the tests, the mechanical properties have been determined and compared and the fracture behaviour has been analyzed by scanning electron microscopy.
Structural Solutions for Ship Hull Plates Strengthening, under Blast Loads
Authors: Chirica Ionel , Beznea Elena Felicia
Published: March 2014

The paper presents selected results of a study concerning the protective capacity of ship hull plates, made out of layered composite plates. A scenario to evaluate the behaviour of the ship structure plate under blast loading is presented. The nonlinear analysis on a 3-D FEM model by using composite elements was performed. The methodology for the blast pressure charging and the mechanism of the blast wave in free air are given. The space pressure variation is determined by using Friedlander exponential decay equation. According to the methods used in this paper an individual pressure-time history to each element based on its distance from the blast is assigned. The dynamic response of the composite plate is shown.
A Special Pipe Support Analysis
Authors: Ilinca Costin , Vasilescu Serban
Published: March 2014

There are many cases in the usual engineering practice when the pipes have to be supported with special items like horizontal and vertical trunions on elbows. Usually these special supports have a geometrical configuration in which the ratio d/D has to be less than 1(d represents the main diameter of the trunion and D the main diameter of the elbows or pipes). In the paper is presented a special finite element analysis for trunions based on the requirements of the ASME Boiler and Pressure Vessel Cod, Section VIII, Division 2. The analysis is limited for the 1.5D bends. The study is realized in two main cases: when the boundary conditions are imposed to the end of a trunion with a limited length and when the boundary conditions are imposed at the end of the real length of the trunion. There are also analyzed some different geometries of trunions in order to obtain the most favorable ratio between the main diameters of the supports and elbows. The forces and moments imposed as boundary conditions for the trunions have been calculated using Coade Caesar 5.30 program. The analysis has been performed in the main load cases such as: sustained, expansion and occasional. The results obtained present the stresses and deflections both in elbows and trunions in order to compare the maximum equivalent stresses with the allowable values. The calculation of the trunions has been completed taking into consideration the heavy thermal loads on the pipes. Some cases of thermal distributions on the trunion have been considered in order to check the most dangerous situation. This study contains also the effect of the corrosion of the pipes and elbows that are connected directly with the trunions.
Bipolar Switching Properties of the Manganese Oxide Thin Film RRAM Devices
Authors: Kuan Min Chang , Yang Fann Wei , Cheng Chien Min , Chen Kai Huang , Lee Jian Tz
Published: March 2014

Up to now, the various non-volatile memory devices such as, ferroelectric random access memory (FeRAM), magnetron random access memory (MRAM), and resistance random access memory (RRAM) were widely discussed and investigated. For these nonvolatile memory devices, the resistance random access memory (RRAM) devices will play an important role because of its non-destructive readout, low operation voltage, high operation speed, long retention time, and simple structure. The resistance random access memory (RRAM) devices were only consisting of one resistor and one corresponding transistor.
The subject of this work was to study the characteristics of manganese oxide (MnO) thin films deposited on transparent conductive thin film using the rf magnetron sputtering method. The optimal sputtering conditions of as-deposited manganese oxide (MnO) thin films were the rf power of 80 W, chamber pressure of 20 mTorr, substrate temperature of 580°C, and an oxygen concentration of 40%. The basic mechanisms for the bistable resistance switching were observed. In which, the non-volatile memory and switching properties of the manganese oxide (MnO) thin film structures were reported and the relationship between the memory windows and electrical properties was investigated.
Synthesis of Porous Ti2SnC from TiH2-Sn-TiC/Graphite Powders in Tube Furnace
Authors: Li Zheng Yang , Wang Li Bo , Zhong Guo Cai , Li Sai Sai , Zhou Ai Guo
Published: March 2014

Titanium tin carbide (Ti2SnC) is a member a MAX phases, which are ternary carbides or nitrides with layered structure. Ti powders are normally used as Ti source to synthesize Ti2SnC. In this paper, TiH2, a relative cheaper Ti source, was used to synthesize Ti2SnC. Ti2SnC was synthesized from TiH2/Sn/TiC or TiH2/Sn/graphite powders by a tube furnace at different temperatures under Ar atmosphere. From the analysis of X-ray diffraction results, the lowest temperature to synthesize Ti2SnC was 1000 °C. Ti2SnC content increased with temperature, and high purity Ti2SnC was fabricated at 1200 °C. From scanning electron microscopy, as-synthesized Ti2SnC from TiH2/Sn/TiC was with plate-like structure. However, for Ti2SnC from graphite as carbon source, there was some stripe microstructure. Some large pores existed between the Ti2SnC particles. The existence of the pores make the mechanical properties of Ti2SnC block significantly reduced, its compressive strength was only 0.483 MPa or 0.35 MPa respectively for samples synthesized from TiC or graphite as carbon source. The low mechanical properties make the porous sample easy to be broken as powders.
Pressureless Sintering of Boron Carbide with Al2O3 and SiC as Sintering Aids
Authors: Li Xiao Guang , Jiang Dong Liang , Zhang Jing Xian , Lin Qing Ling , Chen Zhong Ming , Huang Zheng Ren
Published: March 2014

The effect of Al2O3 and SiC as the sintering additives for pressureless sintering boron carbide (B4C) was investigated. The aids were 10 wt% Al2O3 (10A), 10 wt% Al2O3 and 15 wt% SiC (10A15S), 10 wt% Al2O3 and 30 wt% SiC (10A30S), and 30 wt% SiC (30S) (all based on B4C). The sintering behavior, microstructure evolution and phase compositions of the samples were studied. 10A15S and 10A30S can effectively enhance the densification of B4C, comparing with 10A and 30S. The linear shrinkage rate of 14% for the 10A15S and 10A30S samples can be reached. The bending strength approaching 400MPa for the 10A30S sample sintered at 2170°C can be obtained.
Preparation of High Strength and Lightweight Wall Materials Using Oil Shale Ash as Raw Materials
Authors: Ning Lei , Li Jin Hong , Zhang Qi , Qian Ting Ting
Published: March 2014

In this research, high strength and lightweight wall materials were made from oil shale ash (OSA) by grinding, mixing, casting molding, autoclave curing processes, et al. Factors influencing the bulk density and compressive strength of the wall materials were discussed in detail. X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) analysis were used to characterize the samples. The results indicated that the compressive strength can reach up to 13.42 MPa when the bulk density reduced to 1.11g/cm3 introduced 72.00 % of OSA, the wall materials showed thermal conductivity of 0.12~0.14 W/m k. The main hydration products of the wall materials were calcium hydroxide [Ca (OH)2], C-S-H gelation and hydrogrossular [Ca3Al2(SiO4)(OH)8]. These hydration products are prodominently C-S-H gelation bonded the solid raw materials together tightly and play a great contribution to the compressive strength of wall materials.
Study of Al/SiC Package Substrate for High Power LED
Authors: Wang Shuang Xi , Liu Gao Shan , Yan Jian Yu , Ye Jia Xing
Published: March 2014

LED is the fourth generation of the illumination light source. The light efficiency, lifetime and reliability will be reduced, if the heat generated in LED chips couldn’t be dissipated rapidly. Thus, thermal conductivity of the substrate material is a very key factor in the LED field. Silicon Carbide with Aluminum metal composites (Al/SiC) has high thermal conductivity and ideal thermal expansion coefficient. In this paper, the main kinds of substrates for high-power LED were introduced. Al/SiC composite substrate with excellent heat conduct performance was fabricated by pressureless infiltration technology. The microstructure of Al/SiC was observed by scanning electron microscope (SEM). The coefficients of thermal expansion and thermal conductivity of Al/SiC composite substrate, AlN ceramic substrate and Al2O3ceramic substrate were compared. The results showed that the coefficient of thermal expansion (CTE) of Al/SiC varied from 7.77×10-6K-1to 10.89×10-6K-1, which is compatible with Silicon. And the thermal conductivity of Al/SiC is as 9 times high as that of Al2O3.
Synthesis and Photo-Catalytic Properties of MOO3 Nanosheets
Authors: Zhang Lin , Tu Yue , Cui Jing Hui , Shi Wu Chao , Li Qiang
Published: March 2014

Layered Molybdenum trioxide MOO3, with a two-dimensional (2D) structure was successfully delaminated into colloidal nanosheets in n-butanol via a soft-chemical process involving intercalation of dodecylamine. X-ray diffration (XRD) showd that: after intercalation spacing of the layered material expend from 1.38nm to 2.69nm. Furthermore, stable nanosheet sol was obtained after exfoliation under ultrasonic condition, Characterizations by transmission electron microscopy (TEM) and scan electron microscopy (SEM) confirmed the formation of unilamellar 2D nanosheet crystallites with an average lateral size of 400 nm, those also suggests that the samples we got is Lamellar structured. Selected Area Electron Diffraction (SEDA) indicates that the obtained nanosheets were crystalline. And the obtained nanosheets exhibited photo-catalytic decolorization properties. Which was evaluated by monitoring the degradation of Methylene Blue, after 40 minutes 90% methylene blue was degradated.
Hot-Press Sintering Densification, Microstructure and Properties of SiC-TiB2/B4C Composites
Authors: Zhu Bao Xin , Zhang Yu Jun , Wang Hong Sheng , Wang Chong Hai , Yue Shuang Shuang
Published: March 2014

SiC-TiB2/B4C composites were fabricated by hot-press sintering B4C with silicon powder and tetrabutyl titanate (precursor of TiO2) as sintering and reinforcement agents. The influence of additives on hot-press sintering densification, microstructure and properties of composites were studied. The results showed that TiB2 and SiC generated by chemical reaction between additives and B4C matrix reinforced the sintering activity of the mixed powders and accelerated significantly the hot-press sintering densification rate of B4C from 1200 °C to 1700 °C. According to the SEM observation, the second phase of TiB2 and SiC particles synthetized in situ sited along the grain boundaries of B4C, meanwhile, those SiC particles of nanoscale size embedded into the B4C grains, and thereby, intra/inter-type ceramics formed. The maximum relative density of 98.1% was obtained with 9wt.% TiO2. The typical valus of Vickers hardness, bending strength and fracture toughness can reach 26.7 GPa, 580 MPa and 5.0 MPam1/2, respectively.
Modulating Release of Metoprolol Tartrate with Nanostructured Silica Particles
Authors: Jia Xiao Yun , Wu Ya Zhen , Cai Qing , Yang Xiao Ping , Liu De Ping , Lin Yuan Hua
Published: March 2014

To develop a kind of gastrointestinal timed-release preparation for Metoprolol Tartrate, nanostructured silica particles were chose for the purpose. Briefly, MCM-41 type mesoporous silica nanospheres with a size of 100-200 nm were synthesized through the reaction of tetraethyl orthosilicate (TEOS) in the water medium at 353 K, with introducing some cetyltrimethyl ammonium bromide (CTAB) as porogens. Various analytical methods, including FT-IR, XRD, TEM, N2 physisorption and thermal analysis, were applied to characterize the final products. Metoprolol Tartrate was then loaded into the mesoporous silica nanospheres by soaking. Results of the release of the drug in simulated gastric juice indicated that the drug can release up to 24 h and its maximum released amount was 4.5%. In the simulated intestinal juice the maximum cumulative released amount of metorprolol was 10.8%.In vitro release behavior revealed that the mesoporous silica were appropriate used as drug delivery system.
Effect of Ni Coated SiC on Mechanical Properties of SiC/Fe Composites
Authors: Wang Bin Bin , Fan Bing Bing , Li Wen , Wang Chen Yang , Sun Bing , Zhao Biao , Pian Xiao Xuan , Chen Hao , Zhang Rui
Published: March 2014

A facile onestep in situ chemical deposition method was introduced to synthesize Ni coated SiC composite powders, which used NiCl2·6H2O as nickel source and N2H4·H2O as reductant, respectively. SiC(Ni)/Fe composites were prepared by current-vacuum hot-pressed sintering at 850°C, 40MPa for 30min. Scanning electronic microscope (SEM) and X-ray diffraction (XRD) were used to characterize the structure, morphology and composition of the prepared Ni/SiC core/shell composite powders. It is found that the Ni coated SiC is favorable to improve the dispersion and compatibility of SiC(Ni)/ Fe composites. By a series of contrast experiments, it is shown that the sintering sample with 5wt% of SiC(Ni) has the best mechanical properties. The relative density, Vickers hardness and bending strength is 91.67%, 4.72GPa and 508MPa, respectively.
Synthesis and Microstructure Characterization of Gd- and Sc-Co-Doped BaTiO3 Nanopowders via Sol-Gel Method
Authors: Yu Dan , Zhang Qi Long , Yang Hui , Zhou Jue Hui
Published: March 2014

The effects of rare-earth ions Sc3+ and Gd3+ on phase transition, microstructure and dielectric properties were investigated systematically. Gd-and Sc-co-doped nanopowders were synthesized via one-step sol-gel method. After xerogel was calcined at 800 °C for 2h, (1x)BaTiO3-xGdScO3 (0 x 0.06) nanopowders with narrow particle distribution was obtained. The nanopowders were then pressed into pellets and sintered at 1300~1450 °C respectively. The results indicated that the dielectric peaks of samples were broadened since double doping restrained the grain growth of BaTiO3 ceramics. For x = 0.06, pellets sintered at different temperatures can obtain a low curie temperature of 25 °C. Meanwhile, accompanied by an increasing sintering temperature, the dielectric loss of samples decreased gradually, achieving a optimal value of 1.1%.
Effects of ZnO Doping on Microstructure, Dielectric and Ferroelectric Properties of La2Ti2O7 Ceramics
Authors: Chen Gang , Peng Xiao Dong , Deng Chun Lin , Fu Chun Lin , Cai Wei , Deng Chun Yan , Li Xiao Shuang
Published: March 2014

The La2Ti2O7+xwt%ZnO(x=0, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5) ceramics were prepared by the conventional solid state reaction method, and effects of ZnO doped on the structure, dielectric and ferroelectric properties were investigated in detail. The X-ray diffraction patterns of La2Ti2O7ceramics doped by ZnO oxide showed that no second phase exists. The surface morphology is palte-like shape, the grains of La2Ti2O7ceramics increase with increasing the content of ZnO, and the result is to improve the density of La2Ti2O7ceramics. The dielectric constant and loss decreases with increasing frequency.When the content of ZnO is more than 0.05wt%, the dielectric constant and loss decreases with the amount of addition of ZnO oxide increasing. The ferroelectric hysteresis loop is not saturable, which is attributed to its large leakage current. The ferroelectric properties improve with the addition of ZnO oxide. .
Effect of Ti:Fe Ratios on the Phase Structures and Properties of Iron Titanium Oxides
Authors: Guo Mei , Xu Xing Ru , Wang Xi Xin , Yu Wei , Wang Si Yu , Zhao Jian Ling
Published: March 2014

Iron titanium oxides with different Ti:Fe ratios (molar ratio: 3:1, 2:1, 1:1, 1:2, 1:3) have been prepared by chemical coprecipitation process. The structures and properties of the samples have been characterized by X-ray diffraction, vibrating sample magnetometer and UV-vis spectrophotometer. Results show that the samples annealed at 460 °C have poor crystallinity. At 550 °C, the crystallinity of all the samples increased strikingly. The iron titanium oxides contained anatase TiO2, rutile TiO2, α-Fe2O3and/or Fe2TiO5. Ti:Fe ratios have a great influence on the detailed phase compositions of each sample. The iron titanium oxides exhibited paramagnetism and the intensity of magnetization increased with the increasing content of Fe. Band gap energies of the oxides changed slightly with increasing content of Fe with an average value of 2.0 eV, obviously lower than that of TiO2.
Electrical Characteristics in Transparent (Bi3.25Nd0.75)(Ti2.9V0.1)O12 Ferroelectric Thin Films
Authors: Yang Fann Wei , Cheng Chien Min , Chen Kai Huang
Published: March 2014

In this study, we investigated the structure and ferroelectric properties of the as-deposited (Bi3.25Nd0.75)(Ti2.9V0.1)O12ferroelectric thin films on ITO substrate fabricated by rf magnetron sputtering method. The electrical, ferroelectric and physical characteristics of as-deposited (Bi3.25Nd0.75)(Ti2.9V0.1)O12thin films were developed under different conditions to find the optimal deposited parameters. The crystalline structure of the prepared (Bi3.25Nd0.75)(Ti2.9V0.1)O12thin films was analyzed by X-ray diffraction (XRD). Field emission scanning electron microscopy (FESEM) was used to observe the film thickness and the surface morphology including grain size and porosity. Additionally, the remnant polarization of the as-deposited ferroelectric thin films was improved by neodymium and vanadium elements doped in this study. The remanent polarization of as-deposited ferroelectric thin films was 11 μC/cm2as the measured frequency of 1kHz. Finally, the polarization of as-deposited ferroelectric thin film capacitor was decreased by 9% after the fatigue test with 109switching cycles.
Influence of Bacteria Pseudomonas fluorescens on the Properties of Latvian Clay
Authors: Rundans Maris , Sperberga Ingunda , Sedmale Gaida , Vecstaudza Dagnija , Muter Olga
Published: March 2014

Wide varieties of bacteria are able to produce extracellular polymeric substances (EPS) which are mostly composed of polysaccharides. It is suggested that EPS substances can alter certain clay soil properties due to their ability to adhere to the surface of mineral particles. Most common used microorganisms by the researchers for this purpose are of either genus Bacillus or genus Pseudomonas. In this study growth of bacteria P. fluorescens AM PS11 culture in locally obtained clay is studied for the purpose of establishing their influence on rheological properties of clay. An attempt to evaluate it has been made using FT-IR and XRD. Change in plasticity of clay using Atterberg limits method and coefficient of drying sensitivity has also been determined.
Determining the Number of Peaks of Rough Surfaces Necessary for Wear Calculation
Authors: Linins Oskars , Leitans Armands , Springis Guntis , Rudzitis Janis
Published: March 2014

The problem of evaluating the life period of different mechanisms is of great importance nowadays. This could be explained by the fact that the wear process is very complex and very many factors take place simultaneously. During the history a variety of theories that offered different methods of wear calculation models were developed. However still there is no exact wear calculation model that could be applied to all cases of wear processes. The offered method is dealing with the calculation of rough surface peaks that make the contact between two surfaces. Taking into account the number of these peaks and applying fatigue wear model based on 3D surface micro-topography, assessing the materials physical and mechanical characteristic quantities and considering definite service conditions of sliding friction pair it is possible to make the wear calculation of friction pair under definite working conditions.
Tribological Testing and Modeling of Elastomeric Materials
Authors: Vaajoki Antti , Laukkanen Anssi , Waudby Richard , Kivikytö-Reponen Päivi , Valtonen Kati , Kuokkala Veli Tapani
Published: March 2014

In applications which experience repeated impacts by hard abrasive particles at high or moderate strain rates, elastomers are commonly used. The goal of the current work is to develop a methodology involving scratch testing and modeling which would be simple and cost effective for capturing the failure and wear behavior of elastomeric materials. The high failure strains as well as the extremely good wear resistance of elastomers make this task a formidable challenge. Modeling of a scratch test, however, seems to be promising in this regard.
Is God (in)konsekwent? Heerskappy, oorweging en aanspreeklikheid in die Dawidsgeskiedenis in die boeke van Samuel
Authors: Helberg Jaap L.
Published: March 2014

As ’n eenheid openbaar die Samuelboeke die aanspreeklikheid van mense in hulle verhouding tot mekaar en tot God. Hierdie artikel ondersoek die vraag na God se konsekwentheid wat ook die vraag impliseer of alles onder sy heerskappy plaasvind. Die bevinding is dat alles onder God se allesoorkoepelende, vrymagtige en persoonlike heerskappy gebeur. Vir die beperkte menslike oorweging is dit geheel en al onpeilbaar anders. Dit is nie ’n nuutskepping oor sy Woord wat die lig bring nie, maar die nuutontdekking in sy Woord. Hy laat reg en geregtigheid geld, maar in ’n nog sterker mate ook sy genade. Uiteindelik is sy konsekwentheid – ‘die dwaasheid van die kruis’ – ten volle geopenbaar in die verwagte Messias, Jesus Christus. In die huidige stukkende werklikheid oefen God ook sy heerskappy uit deur persone wat hulle eie agendas het, selfs bose agendas. So laat Hy gelowiges tot selfontdekking, berou en bekering oor hulle sonde kom. Hulle leef met kinderlike vertroue op God en volgens die groot gebod van die liefde.The books of Samuel as a unity reveal the accountability of people in their relations to each other and to God. This article explores the issue of God’s consistency, including the question whether everything happens under his reign. The finding is that everything happens under his all-embracing, all-powerful and personal sovereignty, which is unfathomable by the limited human deliberation. It is not a new creation about his Word which brings the light, but the new discovery in his Word. He asserts justice, and to an even greater extent, his grace. His consistency – ‘the foolishness of the cross’ – is ultimately fully revealed in the expected Messiah, Jesus Christ. In the present broken reality God also asserts his sovereignty through people who have their own agendas, even evil agendas. Thus, He brings believers to self-discovery, remorse and repentance from their sins. They live with childlike trust in God and according to the great commandment of love.
Medical professionalism from a socio-cultural perspective
Authors: Ganasegeran K , Al-Dubai SAR
Published: March 2014

Context:

The practice of medicine requires good communication skills to foster excellent rapport in doctor patient relationship. Reports on communication skills learning attitude among medical professionals are key essentials toward improving patient safety and quality of care.

Aims:

We aimed to determine factors affecting communication skills learning attitudes among medical residents in Malaysia.

Settings and Design:

Cross-sectional survey, in a Malaysian public health hospital.

Materials and Methods:

A total of 191 medical residents across medical and surgical based rotations were included. We assessed the validated communication skills attitude scale among medical residents from different rotations.

Statistical Analysis:

Statistical Package of Social Sciences (SPSS®) (version 16.0, IBM, Armonk, NY) was used. Cronbach's alpha was used to test the internal consistency of the scale. Descriptive analysis was conducted for all variables. Bivariate analysis was employed across the socio-demographic variables.

Results:

Majority of the residents believed that communication skills training should be made compulsory in Malaysia (78.5%). Medical residents agreed that acquiring good communication skills is essential to be a good doctor. However, the majority cited time pressures for not being able to learn communication skills. Significant differences in communication skills learning attitude scores were found between Malays and Chinese.

Conclusion:

The majority of medical residents had a positive attitude toward communication skills learning. Socio-demographic factors influenced communication skills learning attitude among medical residents. Incorporating communicative skills modules during hospital Continuous Medical Education for medical residents is essential to cultivate communicative skills attitudes for effective doctor-patient relationship during the routine medical encounters.
Unusual way of loosened total hip arthroplasty treatment with an Austin Moore endoprosthesis
Authors: Erceg M , Becic K
Published: March 2014

A 65-year-old female patient with aseptic loosening of total cemented hip endoprosthesis and pathologic fracture of the femur at the level of the stem of endoprosthesis was presented. As no appropriate endoprosthesis was available due to the war in Croatia and war priority, the problem was managed by femur osteosynthesis and implantation of a partial Austin Moore hip endoprosthesis. The endoprosthesis is still functioning well (for 20 years). To the best of the author's knowledge, nobody has ever treated problem like this using this alternative, an unconventional method, with an Austin Moore endoprosthesis.
Therapy-related acute promyelocytic leukemia following etoposide-based chemotherapy in non-seminomatous germ cell tumor
Authors: Kumar TN , Krishnamani  , Gandhi LV , Raghunadharao D , Sadashivudu G
Published: March 2014

Therapy related AML (t- AML) accounts for 10-20% of all cases of AML. Cytotoxic agents implicated are alkylating agents, topoisomerase II inhibitors and rarely anti metabolites and anti tubulin agents. A growing incidence of therapy related acute promyelocytic leukemia (t-APL) has been reported over the last few decades in malignant and non malignant conditions. To the best of our knowledge this is the first t-APL case report to be reported in NSGCT post etoposide based therapy.
Unsaturated Flow Characterization Utilizing Water Content Data Collected within the Capillary Fringe
Authors: Baehr Arthur L. , Reilly Timothy J.
Published: March 2014

An analysis is presented to determine unsaturated zone hydraulic parameters based on detailed water content profiles, which can be readily acquired during hydrological investigations. Core samples taken through the unsaturated zone allow for the acquisition of gravimetrically determined water content data as a function of elevation at 3 inch intervals. This dense spacing of data provides several measurements of the water content within the capillary fringe, which are utilized to determine capillary pressure function parameters via least-squares calibration. The water content data collected above the capillary fringe are used to calculate dimensionless flow as a function of elevation providing a snapshot characterization of flow through the unsaturated zone. The water content at a flow stagnation point provides an in situ estimate of specific yield. In situ determinations of capillary pressure function parameters utilizing this method, together with particle-size distributions, can provide a valuable supplement to data libraries of unsaturated zone hydraulic parameters. The method is illustrated using data collected from plots within an agricultural research facility in Wisconsin.
Assessment of Particulate Matter Levels in Vulnerable Communities in North Charleston, South Carolina prior to Port Expansion
Authors: Svendsen Erik R. , Reynolds Scott , Ogunsakin Olalekan A. , Williams Edith M. , Fraser-Rahim Herb , Zhang Hongmei , Wilson Sacoby M.
Published: March 2014

Introduction

The Port of Charleston, one of the busiest US ports, currently operates five terminals. The fifth terminal is being planned for expansion to accommodate container ships from the proposed Panama Canal expansion. Such expansion is expected to increase traffic within local vulnerable North Charleston neck communities by at least 7,000 diesel truck trips per day, more than a 70% increase from the present average rate of 10,000 trucks per day. Our objective was to measure the current particulate matter (PM) concentrations in North Charleston communities as a baseline to contrast against future air pollution after the proposed port expansion.

Methods

Saturation study was performed to determine spatial variability of PM in local Charleston neck communities. In addition, the temporal trends in particulate air pollution within the region were determined across several decades. With the BGI sampler, PM samples were collected for 24 hours comparable to the federal reference method protocol. Gravimetric analysis of the PM filter samples was conducted following EPA protocol.

Results

The range of the PM10 annual average across the region from 1982 to 2006 was 17.0-55.0 μg/m3. On only two occasions were the records of PM10 averaged above the 50.0 μg/m3 national standard. In the case of PM2.5, the annual average for 1999-2006 ranged from 11.0 to 13.5 μg/m3 and no annual average exceeded the 15.0 μg/m3 PM2.5 annual standard.

Conclusions

Although ambient PM levels have fallen in the Charleston region since the 1960s due to aggressive monitoring by the stakeholders against air pollution, local air pollution sources within the North Charleston neck communities have consistently contributed to the PM levels in the region for several decades. This baseline assessment of ambient PM will allow for comparisons with future assessments to ascertain the impact of the increased truck and port traffic on PM concentrations.