bluuebunny/crossref_metadata_2025 huggingface dataset:
Re-Engineering of an Inlet Air Filtration System for a 100MW Combined Cycle Cogeneration Power Plant
Authors: Dorschel Moritz , aus der Wiesche Stefan
Published: March 2012

Inlet air filtration systems are essential components for any power plant based on gas turbines, because poor air quality can significantly impact the operation and performance of the gas turbine. But higher pressure losses due to the filtration system have a negative impact to the power plant performance. In this paper, the field experience with a typical inlet air filtration system for a modern 100MW (electric) combined cycle cogeneration power plant (called “HKW Hafen”, Muenster, Germany) is discussed. The long-term observations demonstrated clearly the importance of the filtration system. A poor filtration performance was found for the initial system, and a re-design was initiated. With regard to this task, the use of computer-aided engineering tools (CAE) has proven its reliability. This approach enables an efficient tool for searching customized solutions for a specific power plant with a high confidence level. It was found that frequently used guidelines and supplier information are not completely sufficient for precise cost saving calculations.
Influence of the Structure of Micro Premixing Chamber on the Uniformity of Flow Distribution and Premixing Characteristics
Authors: Yan Yunfei , Zhang Li , Ran Jingyu , Zhang Jie
Published: March 2012

In micro combustors, the residence time of gas is dramatically reduced. It is much more important to improve combustion efficiency and stability of the micro-combustor by improving the uniformity of flow distribution and mixed results in micro premixing chamber. The flow distribution in micro premixing chamber is analyzed. The influence of micro premixing chamber structures (including the diameter of fuel inlet, numbers of arc-shaped and straight micro-channels, distance and numbers of subordinate fuel inlets) on the uniformity of flow distribution and premixing characteristics is numerical investigated. The influence of the different structure of micro premixing chamber is gained. It is an important guide for designing high efficient micro premixing devices.
Numerical Simulation of Unsteady Flow Phenomena and Exciting Force in Control Stage of Steam Turbine Under Multiple Working Conditions
Authors: Qu Huancheng , Zhang Di , Xie Yonghui , Cao Shouhong , Wu Qilin
Published: March 2012

Partial admission is applied wildly to regulate the power in turbomachinery. The prominent unsteady characteristic has a great effect on the aerodynamic performance and unit safety. The RNG k-ε turbulence model, dual time step method, sliding interface model and structural hexahedron mesh were adopted and the 3-D unsteady viscous model for the full annulus of the control stage of 300MW steam turbine with admission room and reinforced rib was constructed. The flow phenomena and exciting force were investigated detailed in multiple working conditions. The time-averaged unsteady wheel efficiency is over 3% lower than that from steady analysis with two different degrees of admission. The rotor blades experience large unsteady axial and tangential forces while passing the blocked channel. Spectrum analysis was performed and 50.0Hz is seen as the typical low frequencies. The largest amplitude of unsteady forces under the condition of three valves opened (ξ = 0.70) is at the first multiple rotational frequency due to the circumferential nonuniformities of flow domain, while the largest amplitude under the condition of two valves opened (ξ = 0.47) is at the second multiple rotational frequency due to the circumferential periodicities of flow domain. These provide essential parameters for strength and vibration analysis of blade. The pressure and static entropy plots show that the circumferential distributions are nonuniform and the nonuniformities decrease while moving towards the downstream sections in the two conditions. The entropy is significantly large, which means that the mixing and windage losses are huge resulting in the decrease of the blade power. The pressure drop moves towards the downsteam blade surface while rotor passing into the blocked channel. The pressure is recovering while rotor passing out the blocked channel.
Study on the Equivalent Stiffness of Heavy-Duty Gas Turbines Composite Rotor With Curvic Couplings and Spindle Tie-Bolts
Authors: Yuan Shuxia , Zhang Youyun , Zhu Yongsheng , Jiang Xiangjun
Published: March 2012

The difference between the composite rotor with curvic couplings & spindle tie-bolts and integrated one is contact interface. For the discontinuous of contact interface, equivalent stiffness deducted method of composite rotor with curvic couplings & spindle tie-bolts is not the same as integrated rotor. In this paper, the rotor was divided into continuous region and region affected by contact interface. And for the latter, the contact interface bear compression and spindle tie-bolts bear tension under bending moment. A method calculating the position of “neutral layer” and equivalent stiffness was obtained, the results were validated by the working process data of gas turbines. Some factors influencing the stiffness and dynamic characteristics of the rotor such as surface roughness, surface waviness and preload were evaluated. The results show that surface waviness has considerable effect on equivalent stiffness and dynamic characteristics, whereas surface roughness alone has minor effect on dynamic characteristics. The preload also affect equivalent stiffness to some extent, and the effect of preload is especially distinct when machining surface quality is poor, so the stiffness can be improved by increasing preload force. If mating surfaces are well grinded and there is no surface waviness, effect on stiffness of surface roughness can be ignored.
Numerical Investigations on the Aerodynamic Performance of Last Stage – Exhaust Hood for Steam Turbines
Authors: Yang Rui , Yang Jiandao , Peng Zeying , Shi Liqun , He Aping , Yang Hong , Zhou Daiwei , Li Jun , Li Zhigang , Yan Xin
Published: March 2012

The aerodynamic performance and internal flow characteristics of the last stage and exhaust hood for steam turbines is numerically investigated using the Reynolds-Averaged Navier-Stokes (RANS) solutions based on the commercial CFD software ANSYS CFX. The full last stage including 66 stator blades and 64 rotor blades coupling with the exhaust hood is selected as the computational domain. The aerodynamic performance of last stage and static pressure recovery coefficient of exhaust hood at five different working conditions is conducted. The interaction between the last stage and exhaust hood is considered in this work. The effects of the non-uniform aerodynamic parameters along the rotor blade span on the static pressure recovery coefficient of the non-symmetric geometry of the exhaust hood are studied. The numerical results show that the efficiency of the last stage has the similar values ranges from 89.8% to 92.6% at different working conditions. In addition, the similar static pressure recovery coefficient of the exhaust hood was observed at five working conditions. The excellent aerodynamic performance of the exhaust hood was illustrated in this work.
LES of Pulverized Coal Combustion Furnaces
Authors: Yamamoto Kenji , Kina Daisuke , Okazaki Teruyuki , Taniguchi Masayuki , Okazaki Hirofumi , Ochi Kenichi
Published: March 2012

LES (large eddy simulation) is applied to combustion simulations of two large scale pulverized coal-fired furnaces. One application is a boiler furnace with the coal feed rate of 3,000 kg/h. The results of LES show good agreement in not only distributions of temperature, NO concentration, and CO concentration on the vertical center line but also NO and CO emissions and UBC (unburned carbon in ash). The calculation error of NO emission is 10%. The other application is a horizontal furnace with a low NOx burner with the coal feed rate of 560 kg/h. LES predicts temperatures and oxygen concentrations accurately; but the standard k-ε model does not. The flame width calculated by the standard k-ε model is narrower than that by LES. These calculated results indicate that the drawback of the standard k-ε model is its low calculation accuracy for the coal jet flame decay and lift-off height.
Start Time Control of Micro Gas Turbine CHP System With Heat Storage
Authors: Kurata Osamu , Iki Norihiko , Matsunuma Takayuki , Maeda Tetsuhiko , Hirano Satoshi , Kadoguchi Katsuhiko , Takeuchi Hiromi , Yoshida Hiro
Published: March 2012

Combined heat and power (CHP) systems are widely used considering the prevention of global climate change and the reduction of energy costs. In distributed CHP systems, both high efficiency of elements and good coordination of the systems are considered as the points to solve. We had been researched and demonstrated the micro gas turbine CHP system with heat storage at Sapporo City University from April 2006 to March 2010. At first, the start times of microturbine (MGT) and heat storage system (HST) was set up by schedule timers. In 2008 the schedule timers were substituted to a new programmable logic controller (PLC) and the start times of MGT and HST were calculated as the function of temperature outside and room temperature. Setting the start time of MGT at maximum 5 hours before 8:00 and interlocking relays of HST on MGT, the start times were calculated from temperature outside and room temperature at 21:00 the day before. Control of start time using PLC was demonstrated from Feb. 21, 2009 to June 1 and from Nov. 16 to Jan. 7, 2010. It is shown the time series data of temperature and analysis of the CHP with the original boiler heating system.
Operating Characteristics of a Small Cryogenic Stirling Engine With a Displacer
Authors: Otaka Toshio , Ito Masaru
Published: March 2012

The green house effect by carbon dioxide issue would make better recognizing the importance of efficient use of energy in terms of high energy conservation measures. Accordingly, attention is drawn to the Stirling cycle machine, which is a perfect Freon free and efficient machine. Most Stirling engines operate in temperature ranges in which the temperature difference between the heat source and heat sink is between 100 K and 700 K, with the room temperature being at the lower end of the operating temperature range. However, information available on engines that utilize the room temperature as the heat source and the ultra-low temperature of liquid nitrogen as the heat sink is scarce. Engines that operate within such temperature ranges are called cryogenic heat engines. If their practical applications are realized, energy that has hitherto been wasted during the use of ultra-low-temperature media can be recovered in the form of electrical energy. We have designed and developed a 500 W class Stirling machine as a cryogenic engine. This paper presents some operating characteristics.
A Formation of Distributed Energy Network and Energy Conservation in a University
Authors: Shimohara Kazuya , Notoji Yuu , Nakagawa Tsuguhiko
Published: March 2012

Recently, cutting the CO2 emissions has been the worldwide problem. In order to reduce the CO2 emissions, it is important to promote the energy conservation and introduce the sustainable natural energy. In this paper, we have been studied to develop a combination energy system of the energy conservation and the natural energy in the Okayama Prefectural University. We have a result that it is possible to cut off the 36% or more CO2 emission with the combination of (1) replacing the air-conditioner from the absorption type to a heat pump type, (2) introducing photovoltaic power generation and (3) changing the car that is used for commute from the internal-combustion engine type to an electric vehicle (EV). In addition to cut the CO2 emission, the studied combination energy system can be presented the high economically method.
Experimental Research on Surface Temperature Measurement of Steam Turbine Rotors Based on IR Thermometry
Authors: Lv Fangming , Wang Kun , Wu Bo , Huang Shuhong , He Guoqiang , Yang Tao
Published: March 2012

The surface temperature measurement of steam turbine rotors is of great importance to thermal stress monitoring and security evaluation. Traditionally, the temperature is calculated indirectly by empirical formulas with the vapors’ temperature measured by thermocouples. However, there is huge deviation among the results from different empirical formulas, and which may lead to inaccuracy that cannot be ignored to some extends. In this paper, the feasibility of surface temperature measurement of steam turbine rotors based on infrared radiation (IR) thermometry was discussed and verified experimentally considering the characteristics of the rotors (e.g. high speed rotation, vibration, high-temperature and high-pressure steam, and temperature variation). In the first experiment, the oxidation of alloy samples named refined 12%Cr steel was conducted in a high-pressure steam vessel, and the spectral emissivity of the samples were measured with a monochromatic pyrometer in 1.6μ m. The results shows that the compact oxidation film on the surface of samples had high emissivity, which fitted with a polynomial of third order to the temperature measurements. Then, in the second experiment, the monochromatic pyrometer was used to detect the surface temperature of metal, which was surrounded with high parameters steam(supercritical parameter: up to 25.7MPa and 395°C). The results indicate that the technology of infrared temperature measurement could be applied to the steam turbine rotors, and the deviation can be controlled under 5°C with appropriate infrared emissivity(e.g. assuming e = 0.85). At last, the uncertainty of the temperature measurements was discussed for further work.
Numerical Simulation Research on Optimizing Blended- Anthracites Combustion in W-Shaped Flame Boiler With Direct-Fired Pulverizing System
Authors: Zhu G. M. , Yao B. , Jiao Q. F. , Duan X. N. , Wu Z. J. , Bin Y. Y. , Chen Y. P.
Published: March 2012

Two modes could be adopted such as pulverizing coal in different mills’ and ‘blending before furnace’. When blending different kind of coal, for “blending before furnace ’that means the different coals are blended previously before they are transported into Coal bunker and different mills pulverize same raw coal; on the other hand, Pulverizing coal in different mills’ means that different raw coals enter different mills, that is to say, different mills pulverize different raw coal. It is often held that it is unnecessary to optimize coal-blending mode since there are no essential difference of combustion characteristic etc. between anthracites. To determine the necessity of optimize mode when blending one anthracite with another anthracite, numerical simulation is carried out under different conditions using dual-mixture fraction/PDF approach. The calculated result shows that the furnace temperature field, oxygen distribution and velocity field are quite symmetrical under the ‘blending before furnace mode. But In contrast of that on the mode of pulverizing coal in different mills, the burn-off degree of powder coal and furnace outlet temperature are much lower. Even if using the same ‘pulverizing coal in different mills’ mode, if the mills running mode is changed, the efficiency of the boiler exist a gap from one to another. The simulation results prove that ‘pulverizing coal in different mills’ can enhance the combustion efficiency of boiler greatly even when one kind of anthracite is blended with another kind of anthracite. The operation mode of the coal-mills affect the furnace temperature field clearly and it could decrease coking tendency when the coal which is prone to be coked and so it is arranged far from the side wall of furnace.
Combustion Monitoring and Control in a Reheating Furnace
Authors: Luo Zi-Xue , Ling Xiao , Zhang Xiang-Yu , Zheng Shu , Zhou Huai-Chun
Published: March 2012

In this paper, the combustion monitoring system at different inputs of burners in a reheating furnace by choosing the second heating section as the research subjects based on flame image processing technology has been discussed, and a linear temperature model has been developed for practical combustion control. In the linear model, the gas and air flow of burners in each section are mainly taken into account. The reheating furnace combustion control coefficients of the linear model from in-situ furnace combustion process by date acquisition system have been resolved.
Experimental Research on Environmental Crosswind Effects to Airflow Rate in Wet Cooling Tower
Authors: Gao Ming , Wang Nini , Shi Yuetao , Zhao Yuanbin , Sun Fengzhong
Published: March 2012

The circumferential inflow air distributing rules on the bottom of wet cooling tower are studied by thermal state model experiment under crosswind conditions. Researches showed the axisymmetric distribution of circumferential inlet wind is destroyed under crosswind conditions. And this phenomenon is very obvious when environmental crosswind velocity is more than 0.2m/s. Compared with windless conditions, when environmental wind velocity is about 0.4m/s, the circumferential inlet wind velocity in windward side is about 1.8 times of windless conditions, but the circumferential inlet wind velocity in leeward side is about 0.3 times of windless conditions. Thus, the environmental crosswind affects airflow rate entering into the cooling tower, and deteriorating the heat and mass transfer performance. In addition, the relationship of air gravity wind velocity and crosswind is received that can be acted as the theoretical basis of deep research.
Transient Analysis for Effect of TDFWP on the Operation of Main Equipments in Direct Air-Cooled Thermal Power Generating Unit
Authors: Yang Chen , Tang Shengli
Published: March 2012

For the air-cooled thermal power generating unit, specific climatic conditions exert fast and great impact on the condenser pressure. When equipping turbine driven feed water pumps (TDFWP), as the exhaust steam leaving the boiler feed pump turbine (BFPT) is directly discharged into the air-cooled system, the change of environmental conditions such as air temperature and wind speed will result in the distinct change of BFPT back-pressure both in scope and magnitude. For once-through boilers, such changes will cause disturbance to feed water, and further lead to the change of fuel and air feeding. The back-pressure of main steam turbine is much higher in summer climatic condition. In order to maintain rated or certain power load, steam supplied into the main steam turbine has to be increased. Meanwhile, it is necessary to increase the steam flux in the driving turbine to maintain the needed power for feed water pumps, so there is a conflict that the driving turbine for feed water pumps will compete for steam with the main steam turbine. A dynamical mathematical model of a 600MW direct air-cooled thermal power generating unit is built in this paper. The focus is on the transient analysis of the effect of TDFWP on main equipments when the back-pressure changes in the manners of slope and step mutations. Simulation results show that when the disturbance is smaller, the unit can be quickly adjusted to the operational status at given steam and feed water flow rates. The greater the magnate of back-pressure mutation, the greater the changing range of the parameters, and the longer time is needed for adjusting. Under the condition of the same change magnitude of back-pressure, when the back-pressure rise time is longer, the parameters fluctuation is smaller. When the disturbance is larger, the steam flow of TDFWP is gradually increased to its maximum value. With further increase in the back-pressure, the steam flux in the turbine of TDFWP is gradually decreased, so it is difficult to ensure the feed water flow in this case. The results in this study provide important theoretical significance and engineering reference for the implementation of utilizing direct cooling steam feed pump technology in the actual unit.
Performance Optimization of Silicon Cells by Solar Spectrum Splitting Technology
Authors: Wang Tao , Shou Chunhui , Wang Cheng , Luo Zhongyang , Ni Mingjiang , Cen Kefa
Published: March 2012

Silicon cell is one of the promising technologies which can convert the incident solar radiation into electric power directly. Meanwhile, PV conversion is a highly spectrally dependent quantum process and most silicon PV cells have good spectral response from 400nm to 1100nm. In this paper, a solar beam splitting technology is introduced, which uses an optical thin-film filter that can be applied to hybrid solar system such as photovoltaic/thermal (PV/T) systems. In addition, we summarize the filter design theory and the performance of optical dielectric thin-film interference filter. The next parts of this paper involve the calculation of the cell temperature and efficiency including the analyze models and results. The final conclusion is that, at the same condition of incident solar radiation and cooling effect, the cell efficiency is higher in the solar splitting system compared to that without splitter.
Combining Fuel Rich/Lean Burner With the Small Heavy Oil Gun Ignition Techniques Makes Pulverized Coal-Fired Boiler More Efficient
Authors: Mo Guiyuan , Zhou Hao , Chen Feng , Yin Hong , Qiu Kunzan , Cen Kefa
Published: March 2012

The coal qualities changes very frequently in China, to make the flame stability under different operating conditions is difficult and it is important to prevent the furnace from the serious slagging while the coals with low ash fusion temperature are combusted, at the same time, the utility units now face the frequent load changing, how to save the oil at the low load or during the start up period becomes a very serious problem. In this work, the burner combing the fuel rich/lean separator and the small heavy oil gun ignition techniques were developed and then employed in a utility boiler. The detailed design of such a novel burner is introduced in this paper. Such a burner can achieve a 50% rated load and 70% heavy oil can be saved.
Electrical properties and radiation detector performance of free-standing bulk n-GaN
Authors: Lee In-Hwan , Polyakov A. Y. , Smirnov N. B. , Govorkov A. V. , Kozhukhova E. A. , Zaletin V. M. , Gazizov I. M. , Kolin N. G. , Pearton S. J.
Published: March 2012

Electrical properties and deep electron and hole trap spectra were measured for undoped n-GaN cut from a thick boule grown by hydride vapor phase epitaxy (HVPE). The material is characterized by a very low concentration of residual donors (1013–1014 cm−3) in the first 30 μm near the growth surface. The bulk electrical properties were similar to those of standard high quality undoped bulk HVPE n-GaN, with a net donor concentration of ∼1016 cm−3 and mobility ∼1000 cm2/V s. The strong decrease of electron concentration in the surface region of the high resistivity GaN was caused by the compensation of shallow residual donors by a high density (∼6 × 1015 cm−3) of hole traps with activation energy of 0.2 eV, confined to the compensated region. In addition, other hole traps H5 with activation energy 1.2 eV and concentration 5 × 1015 cm−3 were present. These latter traps had similar concentrations in both the high resistivity and standard conducting HVPE GaN. Radiation detectors prepared on the high resistivity material showed charge collection efficiency (CCE) close to 100% for spectrometry of α-particles with energy up to 5.1 MeV. The CCE dependence on voltage indicated a strong trapping of holes in the active region of detectors by the H5 hole traps.
Extrachromosomal MicroDNAs and Chromosomal Microdeletions in Normal Tissues
Authors: Shibata Yoshiyuki , Kumar Pankaj , Layer Ryan , Willcox Smaranda , Gagan Jeffrey R. , Griffith Jack D. , Dutta Anindya
Published: March 2012

MicroDNA, Microdeletion?

Extrachromosomal circular DNA (eccDNA) is widespread in eukaryotes.

Shibata
et al.

(p.
82
, published online 8 March) have found a new form of eccDNA—microDNA—in embryonic mouse brain, heart, and liver in adult mouse brain and in mouse and human cell lines. Unlike eccDNA, which is derived from repetitive sequences, transposable elements, or viral genomes, circular microDNA is derived from nonrepetitive genomic sequences and, very often, regions associated with genes. Length profiles—at 200 to 400 base pairs long—suggest that microDNA preferentially arises from regions of DNA occupied by nucleosomes. Furthermore, microDNA has very short regions of micro-homology at the beginning and ends of the circles. Analysis of several very common microDNAs indicates that their formation seems to result in microdeletions in somatic and germline genomes.
A Segmentation Clock with Two-Segment Periodicity in Insects
Authors: Sarrazin Andres F. , Peel Andrew D. , Averof Michalis
Published: March 2012

Tic-Toc Segmentation Clock

Molecular oscillators are an essential component of vertebrate segmentation, but whether they exist in segmented animals in general has been controversial for almost a decade.

Sarrazin
et al.

(p.
338
, published online 8 March; see the Perspective by

Roth and Panfilio

) demonstrate the existence of a segmentation clock in the growth zone of insects. Microsurgical manipulation and embryo culture revealed cyclic expression of the segmentation gene
Tc-odd
in the beetle
Tribolium castaneum
, which suggests that segmentation clocks are a widely shared mechanism that mediates animal segmentation.
Draft Genome Sequence of Sphingomonas echinoides ATCC 14820
Authors: Shin Seung Chul , Kim Su Jin , Ahn Do Hwan , Lee Jong Kyu , Park Hyun
Published: March 2012

Sphingomonas
is a Gram-negative, yellow-pigmented, chemoheterotrophic, strictly aerobic bacterium. The bacterium is known to be metabolically versatile and can utilize a wide range of natural compounds as well as some types of environmental contaminants, such as creosote, polychlorinated biphenyls, etc. Here, we report the draft genome sequence of
Sphingomonas echinoides
ATCC 14820, which will provide additional information to enhance our understanding of metabolic versatility of
Sphingomonas
.
Genome Sequence of
Pseudomonas
sp. Strain PAMC 25886, Isolated from Alpine Glacial Cryoconite
Authors: Shin Seung Chul , Kim Su Jin , Hong Soon Gyu , Ahn Do Hwan , Lee Yung Mi , Lee Hyoungseok , Lee Jungeun , Park Hyun
Published: March 2012

Pseudomonas
spp. have shown characteristics of efficiently metabolizing environmental pollutants and also producing exopolysaccharides known as biofilms. Here we present the draft genome sequence of
Pseudomonas
sp. strain PAMC 25886, which was isolated from glacier cryoconite in the Alps mountain permafrost region and which may provide further insight into biodegradative and/or biofilm-producing mechanisms in a cold environment.
Genome Sequence of a Serotype b Non-JP2 Aggregatibacter actinomycetemcomitans Strain, ANH9381, from a Periodontally Healthy Individual
Authors: Chen Casey , Kittichotirat Weerayuth , Chen Weizhen , Downey Jennifer S. , Bumgarner Roger
Published: March 2012

Gram-negative
Aggregatibacter actinomycetemcomitans
can be distinguished (based on the promoter structure of the leukotoxin operon) into JP2 and non-JP2 genotypes, with the former found to be more pathogenic than the latter. Here we report the first complete genome sequence of a serotype b non-JP2 strain of
A. actinomycetemcomitans
.
Ablation of MMP9 induces survival and differentiation of cardiac stem cells into cardiomyocytes in the heart of diabetics: a role of extracellular matrix
Authors: Mishra Paras Kumar , Chavali Vishalakshi , Metreveli Naira , Tyagi Suresh C.
Published: March 2012

The contribution of extracellular matrix (ECM) to stem cell survival and differentiation is unequivocal, and matrix metalloproteinase-9 (MMP9) induces ECM turn over; however, the role of MMP9 in the survival and differentiation of cardiac stem cells is unclear. We hypothesize that ablation of MMP9 enhances the survival and differentiation of cardiac stem cells into cardiomyocytes in diabetics. To test our hypothesis, Ins2+/− Akita, C57 BL/6J, and double knock out (DKO: Ins2+/−/MMP9−/−) mice were used. We created the DKO mice by deleting the MMP9 gene from Ins2+/−. The above 3 groups of mice were genotyped. The activity and expression of MMP9 in the 3 groups were determined by in-gel gelatin zymography, Western blotting, and confocal microscopy. To determine the role of MMP9 in ECM stiffness (fibrosis), we measured collagen deposition in the histological sections of hearts using Masson’s trichrome staining. The role of MMP9 in cardiac stem cell survival and differentiation was determined by co-immunoprecipitation (co-IP) of MMP9 with c-kit (a marker of stem cells) and measuring the level of troponin I (a marker of cardiomyocytes) by confocal microscopy in the 3 groups. Our results revealed that ablation of MMP9 (i) reduces the stiffness of ECM by decreasing collagen accumulation (fibrosis), and (ii) enhances the survival (elevated c-kit level) and differentiation of cardiac stem cells into cardiomyocytes (increased troponin I) in diabetes. We conclude that inhibition of MMP9 ameliorates stem cell survival and their differentiation into cardiomyocytes in diabetes.
Islet protective and insulin secretion property of Murraya koenigii and Ocimum tenuflorum in streptozotocin-induced diabetic mice
Authors: Dusane Menakshi Bhat , Joshi Bimba N.
Published: March 2012

The present study investigates the antidiabetogenic effects of Murraya koenigii (L.) Spr. and Ocimum tenuflorum  L. on streptozotocin-induced diabetic Swiss mice. Treatment with extracts of M. koenigii (chloroform; MKC) and O. tenuflorum (aqueous; OTA) resulted in proper glucose utilization with an increase in liver glucose-6-phosphate dehydrogenase enzyme activity, and normal glycogenesis in hepatic and muscle tissues. Pancreatic and intestinal glucosidase inhibitory activity observed with MKC and OTA treatment indicated beneficial effects in reducing postprandial hyperglycemia with concomitant improvement in glucose metabolism. The glucosidase inhibition was prolonged, even after discontinuation of MKC and OTA treatment. Normalization of plasma insulin and C-peptide levels was observed in diabetic mice, indicating endogenous insulin secretion after treatment. The histochemical and immunohistochemical analysis of pancreatic islets suggests the role of MKC and OTA in pancreatic β-cell protection and the functional pancreatic islets that produce insulin. The study demonstrates the significance of MKC and OTA in glucosidase inhibition and islet protection in the murine diabetic model. These findings suggest the potential of the extracts in adjuvant therapy for the treatment of diabetes and the possible development of potential neutraceuticals.
NUCLEON EFFECTIVE MASS IN COLD DENSE MATTER
Authors: WANG QING-WU , LI XIAO-YA , LÜ XIAO-FU
Published: March 2012

We study the effective mass of nucleon from chiral perturbation theory in the finite chemical potential. By including in the chiral Lagrangian a chemical potential conjugating to the baryon number density, the calculation of integration over meson momentum has to face complex plain which gives the chemical potential dependence of nucleon mass in dense matter. The results indicate that the interaction between nucleons is attractive at first and then repulsive as the chemical potential increases.
STRUCTURAL AND OPTICAL PROPERTIES OF ZnO THIN FILMS PREPARED BY SPIN COATING METHOD — INFLUENCE OF CONCENTRATION AND SPIN RATE
Authors: LAKSHMIPRIYA V. , NATARAJAN B. , JEYAKUMARAN N. , PRITHIVIKUMARAN N.
Published: March 2012

ZnO thin films were prepared onto the glass substrates by the sol–gel spin coating method for various Zn concentrations and at different spin rates. The influence of concentration of zinc and spin rate on the structural and optical properties of the ZnO thin films were investigated. It was observed that the zinc concentration and spin rate influence the grain size and morphology of the ZnO thin films. The optical band gap energy was found to increase with decrease of Zn concentration and increase in spin speed. The photoluminescence peaks show green radiation at ~485 nm. It was also observed that the enrichment of zinc and variation in spin speed influence the intensity of luminescence peaks.
STRUCTURAL PHASE TRANSITION, ELASTIC AND ELECTRONIC PROPERTIES OF CuXSe2(X = In, Ga) CHALCOPYRITE
Authors: BOUGUETAIA T. , ABIDRI B. , BENBAHI B. , RACHED D. , HIADSI S. , RABAH M.
Published: March 2012

The structural, elastic and electronic properties of chalcopyrite compound CuInSe2 and CuGaSe2 have been investigated using the full-potential linearized muffin-tin orbital method (FP-LMTO) within the frame of density functional theory (DFT). In this approach, the local density approximation is used for the exchange-correlation potential using Perdew–Wang parametrization. The equilibrium lattice parameters, bulk modulus, transition pressure, elastic constants and their related parameters such as Poisson's ratio, Young modulus, shear modulus and Debye temperature were calculated and compared with available experimental and theoretical data. They are in reasonable agreement. In this paper the electronic properties are treated with GGA + U approach, which brings out the important role played by the d-state of noble metal (Cu) and give the correct nature of the energy band gap. Our obtained results show that both compounds exhibit semi-conductor behaviour with direct band gap.
PHOTOCATALYTIC ACTIVITY AND PHOTOCURRENT PROPERTIES OF TiO2 NANOTUBE ARRAYS INFLUENCED BY CALCINATION TEMPERATURE AND TUBE LENGTH
Authors: HOU JIAN , ZHANG MIN , YAN GUOTIAN , YANG JIANJUN
Published: March 2012

In this article, titanium oxide nanotube arrays (TiO2–NTAs) were fabricated by anodic oxidation in an ethylene glycol (EG) electrolyte solution containing 0.25 wt.% NH4F. By varying anodized time and annealed temperature, the obtained nanotube arrays behaved different photocatalytic (PC) activities and photocurrent properties. These samples were characterized by scanning electronic microscope (SEM), X-ray powder diffraction (XRD). It was indicated in SEM images that TiO2 nanotube manifests highly ordered structure which, however, has been completely destroyed when the temperature comes to 800°C. XRD manifested that TiO2 nanotubes with various kinds of length all possessed anatase crystallite when annealed at 500°C; meanwhile, with certain length, TiO2–NTAs annealed at series calcination temperature range of 300–600°C also presented anatase crystallite, which is gradually enhanced with the increment of temperature. At 700°C, mixed structure was observed which was made up of proportions of overwhelming anatase and toothful rutile. Methyl blue (MB) degradation and photocurrent measurement testified that TiO2–NTAs under 4 h oxidation and 3 h of 600°C calcination manifested the highest activity and photocurrent density.
INITIAL PRESTRESS DISTRIBUTION AND NATURAL VIBRATION ANALYSIS OF TENSEGRITY STRUCTURES BASED ON GROUP THEORY
Authors: CHEN YAO , FENG JIAN
Published: March 2012

As conventional approaches for morphology and natural vibration analysis do not make full use of the symmetry of structures, the computational cost is significantly raised with increasing number of nodes. In this paper, we propose a simplified technique used to analyze initial prestress distribution and natural vibration of tensegrity structures based on group theory. First, the conditions of symmetry and equilibrium equations for tensegrity structures were established on the basis of the symmetry-adapted coordinate systems found by group theory. Then the initial prestress modes could be found from the null space of the independent sub-matrix of symmetry-adapted equilibrium matrix. Subsequently, the tangent stiffness matrix and the lumped mass matrix were block-diagonalized using symmetry. The generalized eigenvalue problems were simplified by solving the mutually independent subspaces, with the corresponding natural frequencies and vibration modes obtained. Two illustrative examples demonstrate the general procedure, and show the superiority in reducing the difficulty of initial prestress distribution and natural vibration analysis. When compared with numerical results obtained by Abaqus and those of Murakami, the proposed method is shown to be more accurate and efficient.
EDITORIAL — CULTURAL EVOLUTION IN SPATIALLY STRUCTURED POPULATIONS: A REVIEW OF ALTERNATIVE MODELING FRAMEWORKS
Authors: KANDLER ANNE , PERREAULT CHARLES , STEELE JAMES
Published: March 2012

We consider the dynamics of cultural evolution in spatially-structured populations. Most spatially explicit modeling approaches can be broadly divided into two classes: micro- and macro-level models. Macro-level models study cultural evolution at the population level and describe the average behavior of the considered system. Conversely, micro-level models focus on the constituent units of the system, and study the evolutionary dynamics that emerge out of the interaction between these units. In this paper, we give an overview of the general properties of micro- and macro-level models using the examples of agent-based simulations and of continuum models based in diffusion theory; we highlight how both frameworks account for spatially-dependent processes. We argue that both micro- and macro-level models are well-suited to describe the process of cultural evolution in spatial settings and stress that micro- and macro-level models should not be considered as competing alternatives, but rather as complementary tools that can provide different insights into cultural evolutionary dynamics. Although adding spatial components to any model increases its complexity, we argue (based on the findings presented by contributors to this Special Issue of Advances in Complex Systems), that the incorporation of space into the evolutionary framework is a necessary step towards a more complete understanding of the process of cultural evolution.
IODINE/IODIDE-FREE AND POLYMER HETEROJUNCTION-SENSITIZED HYBRID SOLAR CELL
Authors: YUE GENTIAN , WU JIHUAI , HUANG YUNFANG , XIAO YAOMING XIAOMING , LAN ZHANG
Published: March 2012

An iodine/iodide-free and polymer heterojunction-sensitized hybrid solar cell is fabricated by using 6,6-phenyl- C61 -butyric acid methyl ester (PCBM) as electronic acceptor, poly(3-hexylthiophene) (P3HT) as donor and TiO2 film as substrate. The PCBM–P3HT heterojunction can harvest ultraviolet-visible light, transport charge carriers, replacing the dyes and electrolytes in dye-sensitized solar cell. The cell with a PCBM/P3HT ratio of 1:2 shows a short circuit current of 5.47 mA⋅cm-2, an open circuit voltage of 0.849 V, a fill factor of 0.640 and a light-to-electric energy conversion efficiency of 2.97% under a simulated solar light irradiation of 100 mW⋅cm-2.
DEVELOPMENT OF MICROSPHERES COVERED WITH HYDROXYAPATITE NANOCRYSTALS AS CELL SCAFFOLD FOR ANGIOGENESIS
Authors: IWAMOTO TAKASHI , TERADA TAKAHIRO , KOGAI YASUMICHI , OKADA MASAHIRO , FUJII SYUJI , FURUZONO TSUTOMU
Published: March 2012

We prepared poly(L-lactide-co-glycolide) cell scaffolds coated with hydroxyapatite (HAp) nanocrystals with 50–100 nm in diameter via the Pickering emulsion method. Our cell scaffolds were composed of biodegradable polymers and HAp nanocrystals as a core and shell, respectively. The scaffolds were spherical but displayed uneven shapes when altering a shear speed of homogenization during syntheses. The surface coverage of HAp nanocrystals was examined because the HAp-coating ratio for the scaffolds was an important factor as cell scaffolds in order to enhance cell adhesion. On the basis of scanning electron microscopy observations and thermogravimetric analyses, it was found that the cell scaffolds showed distorted morphologies, and the HAp-coating ratio decreased with increasing the shear speed in the synthesis because shear stress influenced shapes of the scaffolds.
In-situ X-ray Photoemission Spectroscopy Study of Atomic Layer Deposition of TiO2 on Silicon Substrate
Authors: Lee Seung Youb , Jeon Cheolho , Kim Seok Hwan , Kim Yooseok , Jung Woosung , An Ki-Seok , Park Chong-Yun
Published: March 2012

In-situ X-ray photoemission spectroscopy (XPS) has been used to investigate the initial stages of TiO2 growth on a Si(001) substrate by atomic layer deposition (ALD). The core level spectra of Si 2p, C 1s, O 1s, and Ti 2p were measured at every half reaction in the titanium tetra-isopropoxide (TTIP)–H2O ALD process. The ligand exchange reactions were verified using the periodic oscillation of the C 1s concentration, as well as changes in the hydroxyl concentration. XPS analysis revealed that Ti2O3 and Si oxide were formed at the initial stages of TiO2 growth. A stoichiometric TiO2 layer was dominantly formed after two cycles and was chemically saturated after four cycles.
Photoluminescence Study of Defect Levels in CuInS2 Thin Films Grown by Sulfurization Using Ditertiarybutylsulfide
Authors: Liu Xiaohui , Fujiwara Chika , Dou Xiaoming , Chichibu Shigefusa F. , Sugiyama Mutsumi
Published: March 2012

The defect-related photoluminescence (PL) levels of CuInS2 thin films prepared by sulfurization using ditertiarybutylsulfide [(t-C4H9)2S: DTBS] have been investigated. The PL spectra exhibit three low-energy peaks at 1.37, 1.34, and 1.24 eV. On the basis of these PL spectra observed at different excitation intensities, the emissions are attributed to donor–acceptor pair transitions. The ionization energies of donors in CuInS2 thin films are determined to be 125, 150, and 280 meV, which are, respectively, due to indium atom-occupied copper vacancies (InCu), sulfur vacancies (VS), and sulfur atom-occupied copper vacancies (SCu); whereas that of the acceptor is determined to be 100 meV and has been reported to the copper vacancy (VCu). Using these data, a band diagram for the defect levels of CuInS2 thin films prepared by sulfurization is proposed.
Material Properties of Barium Titanate Single Crystal from Modified Time-Dependent Devonshire–Ginzburg–Landau Model
Authors: Imanaga Syunji , Miura Kaoru
Published: March 2012

We simulated and compared the material properties of barium titanate for five states, namely, (1) the orthorhombic state, (2) the orthorhombic state near the orthorhombic–tetragonal phase boundary, (3) the tetragonal state near the orthorhombic–tetragonal phase boundary, (4) the tetragonal state, and (5) the tetragonal state near the tetragonal–cubic phase boundary by using a modified time-dependent Devonshire–Ginzburg–Landau model. We reproduced reasonable variations in piezoelectric coefficients, dielectric susceptibilities, and elastic compliance constants for the above-mentioned five states, especially for the phase boundary states. Moreover, we simulated the hysteresis curves of the dependence of electric polarization and strain on electric field and the dependence of the hysteresis curves on compressive stress. The obtained simulation results are well explained by the polarization rotation or extension, which is made easy by the free energy flattening induced by temperature or electric field.
Characterization of Ionic Impurities Adsorbed onto a 5° SiOx Alignment Film
Authors: Huang Yi , Bhowmik Achintya , Bos Philip J.
Published: March 2012

Dielectric spectroscopy is used to clarify the ion adsorption on a 5° SiO
x
alignment film. The results show that both ion concentration and dc conductivity decrease after ion adsorption. The decrease in ions concentration mainly comes from large ionic impurities, possibly corresponding to the colloids formed by ions associated with water. Also, it is found by simulating the voltage holding ratio (VHR) that the long-term voltage decay is determined by the dc conductivity of liquid crystal (LC), which corresponds to ions whose concentration is kept constant. This is interpreted as evidence for the assumption that ion concentration is determined by the solubility of LCs, which is determined by the water concentration in LCs.
A Study on the Sensitivity of a Spin Valve with Conetic-Based Free Layers
Authors: Son Jangyup , Lim Jongkoo , Ko Jungho , Kim Sanghoon , Lee Soogil , Hong Jongill
Published: March 2012

An exchange-biased spin valve with Conetic-based free layers of Co90Fe10, Co90Fe10/Conetic and Conetic was investigated. The spin valve with the Co90Fe10 free layer showed the highest giant magnetoresistance (GMR) ratio of 4% but showed the lowest normalized sensitivity of 0.02 Oe-1. The GMR ratio of 3% and the normalized sensitivity of 0.07 Oe-1 were obtained for the spin valve with the Co90Fe10/Conetic free layer after annealing. The spin valve having the Conetic free layer showed softer magnetic properties and well-defined smaller anisotropy than the other spin valves. Though the spin valve showed the lowest GMR of 0.4% after annealing, it showed the highest normalized sensitivity of 0.14 Oe-1. Our study shows that further improvement in MR response of spin valves with Conetic-based free layers can make a spin valve sensor promising for detecting extremely low fields.
Characterization of ZnO Nanowire Field Effect Transistors by Fast Hydrogen Peroxide Solution Treatment
Authors: Kwon Taehyeon , Park Woojin , Choe  , Yoon Jongwon , Park Sangsu , Lee Sangchul , Hwang Hyunsang , Lee Takhee
Published: March 2012

This study demonstrates a simple and fast method of the operation mode control for ZnO nanowire field effect transistors (FETs) with hydrogen peroxide (H2O2, 10%) solution treatment for 5–10 s. With this H2O2 treatment, the surface of ZnO nanowires was roughened as confirmed by transmission electron microscopy images and the defect level-related emission was increased from photoluminescence (PL) data. Correspondingly, the threshold voltage of H2O2-treated ZnO nanowire FETs shifted to the positive gate bias direction, leading a transition of the operation mode from depletion-mode to enhancement-mode. This H2O2 solution treatment can be a useful method for controlling the operation mode of ZnO nanowire FETs with a wide threshold voltage shift in a few second solution treatment.
Beam Characteristics of Positively and Negatively Charged Droplets Generated by Vacuum Electrospray of an Ionic Liquid
Authors: Fujiwara Yukio , Saito Naoaki , Nonaka Hidehiko , Ichimura Shingo
Published: March 2012

To develop a vacuum-electrospray beam source for secondary ion mass spectrometry (SIMS), beam characteristics of charged droplets electrosprayed in vacuum were investigated in the negative-ion mode as well as the positive-ion mode. A quaternary ammonium ionic liquid was tested. Experimental results showed that there are differences as well as similarities between the positive-ion mode and the negative-ion mode. Beam current changed greatly with capillary voltage and the flow rate of the ionic liquid. Transient response analysis showed that the vacuum electrospray generated a mixed beam consisting of charged particles of smaller m/z values (m/z∼103) and charged droplets of larger m/z values (m/z∼105 to 106). It turned out that the m/z values of the charged droplets diminished with increasing capillary voltage. Using a three-dimensional positioning stage, the capillary position dependence on the beam characteristics was measured. It proved to be of great importance to align the central axis of a capillary with those of apertures in order to maximize the current component of the charged droplets of the larger m/z values and minimize the ratio of the current component of the smaller m/z values. A high alignment accuracy proved to be required at small gap lengths between a capillary tip and a counter electrode.