共查询到20条相似文献,搜索用时 31 毫秒
1.
Jürgen Mimkes 《Physica A》2010,389(8):1665-1676
Economic growth depends on capital and labor and two-dimensional calculus has been applied to economic theory. This leads to Riemann and Stokes integrals and to the first and second laws of production and growth. The mathematical structure is the same as in thermodynamics, economic properties may be related to physical terms: capital to energy, production to physical work, GDP per capita to temperature, production function to entropy. This is called econophysics. Production, trade and banking may be compared to motors, heat pumps or refrigerators. The Carnot process of the first law creates two levels in each system: cold and hot in physics; buyer and seller, investor and saver, rich and poor in economics. The efficiency rises with the income difference of rich and poor. The results of econophysics are compared to neoclassical theory. 相似文献
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The formation of ohmic contacts to n- and p-type ZnSe is reviewed. The mechanisms for forming reasonable low-resistance ohmic contacts to n-ZnSe are well understood. This results from the fact that the Fermi energy level of ZnSe is unpinned and metals with sufficiently large work functions can make contact to n-type material. However, the situation is reversed for p-ZnSe where a large band gap and large electron affinity make it impossible to find metals with sufficiently large work functions to create an ohmic contact. Instead, the use of HgSe to form low barrier height Schottky contacts and of ZnSe/ZnTe multiple quantum wells (MQWs) to form ohmic contacts is reviewed. Although the MQWs can be used to form ohmic contacts to p-ZnSe, they degrade at high temperatures and high current densities. This is reviewed and shown to be a serious problem for applications to laser diodes. 相似文献
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M. Campbell J. A. Cosgrove C. A. Greated S. Jack D. Rockliff 《Optics & Laser Technology》2000,32(7-8):629-639
A review of laser Doppler anemometry (LDA) and particle image velocimetry (PIV) with their application to the measurement of sound is presented. The fundamental principles behind LDA and PIV are discussed and extended to the application of sound measurement. Special attention is paid to analysis of LDA signals including the Hilbert transform, which enables amplitude information to be obtained about various frequency components of a signal and wavelet analysis, which allows non-stationary signals to be accurately analysed. The influence of the refractive index variations in a medium due to a sound wave on the laser beams of an LDA signal is discussed. Attention is also paid to acoustic streaming which arises due to high-intensity sound, and PIV results are presented to demonstrate the effect. 相似文献
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Carl A. Batt Anna M. Waldron Natalie Broadwater 《Journal of nanoparticle research》2008,10(7):1141-1148
Nanotechnology will be an increasing part of the everyday lives of most people in the world. There is a general recognition
that few people understand the implications of the technology, the technology itself or even the definition of the word. This
lack of understanding stems from a lack of knowledge about science in general but more specifically difficulty in grasping
the size scale and symbolism of nanotechnology. A potential key to informing the general public is establishing the ability
to comprehend the scale of nanotechnology. Transitioning from the macro to the nanoscale seems to require an ability to comprehend
scales of one-billion. Scaling is a skill not common in most individuals and tests of their ability to extrapolate size based
upon scaling a common object demonstrates that most individuals cannot scale to the extent needed to make the transition to
nanoscale. Symbolism is another important vehicle to providing the general public with a basis to understand the concepts
of nanotechnology. With increasing age, individuals are able to draw representations of atomic scale objects, but these tend
to be iconic and the different representations not easily translated. Ball and stick models are most recognized by the public,
which provides an opportunity to present not only useful symbolism but also a reference point for the atomic scale. 相似文献
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Samuel A. Cushman 《Entropy (Basel, Switzerland)》2021,23(12)
Several methods have been recently proposed to calculate configurational entropy, based on Boltzmann entropy. Some of these methods appear to be fully thermodynamically consistent in their application to landscape patch mosaics, but none have been shown to be fully generalizable to all kinds of landscape patterns, such as point patterns, surfaces, and patch mosaics. The goal of this paper is to evaluate if the direct application of the Boltzmann relation is fully generalizable to surfaces, point patterns, and landscape mosaics. I simulated surfaces and point patterns with a fractal neutral model to control their degree of aggregation. I used spatial permutation analysis to produce distributions of microstates and fit functions to predict the distributions of microstates and the shape of the entropy function. The results confirmed that the direct application of the Boltzmann relation is generalizable across surfaces, point patterns, and landscape mosaics, providing a useful general approach to calculating landscape entropy. 相似文献
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EAST运行中的温度改变会导致磁体及冷屏产生形变和位移。为了测量此位移的变化,利用一个延长臂,把位移转移到较易测量的位置,然后采用直滑式电位器把位移变化转换成电压变化并测量出其值,最终转换成位移的变化值。该测量系统解决了EAST装置中磁体和冷屏位移测量的难题。 相似文献
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One of the biggest struggles of biological anthropology is to estimate the biological profile from burned human skeletal remains. Bioanthropological methods are seriously compromised due to bone heat-induced alterations in shape and size. Therefore, it is urgent to improve our ability to estimate sex, age at death, stature, and ancestrality, to recognize peri mortem traumas and differentiate them from fractures due to fire, and to determine what was the intensity of burning, namely maximum temperature and heat exposure length. This review focuses on different methodologies to assess heat prompted changes in bone submicrostructure. Some of these are extensively used in burned bones research, namely infrared and Raman spectroscopy and X-ray diffraction, while others such as neutron spectroscopy and diffraction are rarely applied to bone samples although their contribution may be crucial for establishing new bioanthropological methods for a reliable examination of burned victims. 相似文献
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《Composite Interfaces》2013,20(8):529-541
Glycidoxypropyltrimethoxysilane (GPS) and γ-aminopropyltrimethoxysilane (APS) were used to modify the surface chemistry of polyamide fibre. The surface chemistry was characterised using X-ray photoelectron spectroscopy. The silanol functional group was designed to be introduced on the surface of polyamide fibre to increase its chemical activity by N-alkylation of GPS and hydrolysis of APS, and to improve the poor interfacial adhesion between a polyamide 66 fibre and an aqueous polyurethane polymer adhesive. The microbond test was used to measure the interfacial shear strength between the waterborne PU adhesive and the polyamide fibre. It has been found that APS hydrolysis and GPS-alkylated fibre surface can be used to improve the interfacial adhesion of polyamide fibre to PU. The IFSS can be improved by N-alkylation of GPS from 5.0 to 8.4?MPa. After water immersion at 50?°C for 48?h, then drying, the IFSS increased to 8.8?MPa due to the plasticisation of PU in water. Better interfacial adhesion was also observed by the hydrolysis of APS, but not significantly improved by this method due to the relatively weak hydrogen bond at the interface between APS and polyamide fibre. 相似文献
11.
J. Chamani A. Asoodeh M. Homayoni-Tabrizi Z. Amiri Tehranizadeh A. Baratian M.R. Saberi M. Gharanfoli 《Journal of luminescence》2010,130(12):2476-2486
Combination of several drugs is often necessary especially during long-term therapy. The competitive binding drugs can cause a decrease in the amount of drug bound to protein and increase the biological active fraction of the drug. The aim of this study is to analyze the interactions of Lomefloxacin (LMF) and Colchicine (COL) with human serum albumin (HSA) and to evaluate the mechanism of simultaneous binding of LMF and COL to protein. Fluorescence analysis was used to estimate the effect of drugs on the protein fluorescence and to define the binding and quenching properties of drugs-HSA complexes. The binding sites for LMF and COL were identified in tertiary structure of HSA with the use of spectrofluorescence analysis. The analysis of fluorescence quenching of HSA in the binary and ternary systems show that LMF does not affect the complex formed between COL and HSA. On the contrary, COL decreases the interaction between LMF and HSA. The results of synchronous fluorescence, resonance light scattering and circular dichroism spectra of binary and ternary systems show that binding of LMF and COL to HSA can induce micro-environmental and conformational changes in HSA. The simultaneous presence of LMF and COL in binding to HSA should be taken into account in the multi-drug therapy, and necessity of using a monitoring therapy owning to the possible increase of the uncontrolled toxic effects. Molecular modeling of the possible binding sites of LMF and COL in binary and ternary systems to HSA confirms the spectroscopic results. 相似文献
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The demand on new and highly efficient energy conversion systems and many other advanced applications have suggested perovskites to be important future candidate materials. Though a lot of work has been done to understand and model their structure and properties, further investigation is still needed. Consequently, the development and enhancement of computational methods including molecular dynamics and quantum chemical calculations is one of the main issues regarding the understanding and optimization of perovskites. In this work, Coulomb Buckingham interatomic potential function is investigated to analyze the structure of Calcium Titanate CaTiO3 through the application of Molecular Dynamics via LAMMPS open source code. The results are compared with the results of other potential functions representations, namely Vashishta-Rahman (VR) and Lennard-Jones (LJ) potentials. The understanding of the effect of potential representation on structural properties would lead to deduction of mechanical and thermal properties and to building a platform for adapting the different types of oxide perovskites, or even nonorganic halide perovskites, to enhance their technological aspects. The VR interaction potential was previously proven to be the most effective for describing the phase changes of perovskites and to match the experimental observations. It was also proven in previous studies that the radial distribution function (RDF) undergoes essential changes when replacing LJ with VR. According to the findings of this study, Buckingham potential is shown to produce much closer results to VR than LJ of the radial distribution function. 相似文献
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前期的研究报道了红外光谱能够监测水果变质产生的挥发物质,其方法是将挥发物收集在气室中,利用多次反射的结构来增强光信号。实验中,我们使用开放光程傅里叶变换红外光谱法监测葡萄变质挥发物,尝试了主动和被动两种测量模式。根据红外光谱特征对葡萄品劣变过程中产生的挥发物进行了定性分析,并在研究中测量了葡萄储藏期间挥发物质的红外光谱特征的强度变化,并且根据这种变化规律建立了不同变质阶段的分类方法。此外,还尝试直接从原始光谱中分析挥发物质,证明了挥发物在原始光谱上仍然具有明显的光谱特征。这一研究证实了现场开放式傅里叶变换红外光谱法监测水果变质的可行性。开放光程傅里叶变换红外光谱法所具有的灵活使用性和非接触式在线测量的优点,使其有可能应用于大面积监测储藏中的水果变质问题,并具有进一步定位劣变源的潜力。 相似文献
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针对铝锂合金样品检测其Ag和Li,采用等离子体原子发射光谱法(ICP-OES)同时测定Ag和Li,火焰原子吸收光谱法(FAAS)分别测定Ag和Li,单宁酸分光光度法(VS)测Ag,对不同的光谱测定方法进行了比较,证明了ICP-OES检测铝锂合金中的Ag和Li具有较高的抗干扰性。对比了三种不同的样品消解方法,确定了FAAS测Li采用王水溶样最佳,ICP-OES,FAAS和VS测Ag采用HCl+H2O2体系溶样准确度更高。详细讨论了样品中共存元素Al, Mg, Zr, Ti, Cu的干扰及消除方法。用氨水沉淀消除共存元素Al,Ti,Zr,8-羟基喹啉沉淀分离Mg和Cu的方法消除原子吸收光度法测Ag的干扰;采用磷酸盐沉淀分离Ti而消除原子吸收光度法测Li的干扰;采用与原子吸收光度法测银相同的消除干扰方法,消除上述离子干扰,滤去干扰沉淀后,用硝酸赶盐酸解蔽Ag+离子,同时分解消除8-羟基喹啉的颜色,以消除分光光度法测银的干扰。对比消除干扰前后的结果发现准确度显著提高,证明消除干扰的方法切实有效。将选择的最佳消解体系和干扰消除方法应用于铝锂合金样品的测定,ICP-OES测Li和Ag回收率分别在100.39%~103.01%和100.42%~103.73%之间,FAAS测Li和Ag 回收率分别在95.91% ~99.98%和98.04%~103.67%之间,分光光度法测Ag回收率在98.00%~101.00%之间,测定结果满足分析要求。 相似文献
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Results about fluorescence spectroscopy of natural eumelanin are presented and compared to analogous results related to synthetic eumelanin, with the aim to investigate the structural organization of eumelanin and the role of the protein coat in its optical and structural properties. The spectra of synthetic and natural eumelanin have similar optical spectra, except for the features related to proteins in natural eumelanins. Fluorescence due to ensembles of large oligomer systems has been spectrally distinguished from that due to monomers and small oligomer systems. Nonetheless, the natural (protein-containing) eumelanin results to consist of aggregates having a larger size than that of synthetic eumelanin. 相似文献
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Mobile verbal exchange is viewed as one of the essential problem in the area of cellular networks. A mobile community apparatuses the proper public model to contribute packet of the data services on excessive speed. The packets of data service model are mandatory to improve the quality of service (QoS). This lookup exertion offers the Improvement of QoS and radio get right of entry to 5G Mobile Networks. Towards improve built-in services, a useful resource allocation protocol is applied at “Radio Access Network (RAN)” layer to improve the QoS in 5G. QoS labeling is a form of organizational communication that enables a local hub or exit station to communicate with or signal its neighbors to request special adjusting to of favorable traffic. QoS highlighting is helpful to provide ways for site visitors to adjust. ISP perform well and show full potential of the pervasive network by utilizing the simulation model in 5G’s ultra-low latency, real-time connectivity, significantly increased capacity, and quick speed. This will help to make device connections faster, more efficient, and less prone to delays. Lower, medium, and high frequency bands can be used to categories 5G. Mid-bandwidth enables better cell broadband connections or greater machine-to-machine communication and provides faster connectivity than 4G at close range. 相似文献
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声动力治疗是将低频超声与声敏剂相结合的非侵入性肿瘤治疗方法,由于其副作用小、治疗深度深等优点,受到科学家们的重视。有机声敏剂作为初代声敏剂已经被研究多年,但是其水溶性差、无法在肿瘤部位大量聚集等缺陷阻碍了其声动力应用。快速发展的纳米技术为许多问题的解决提供了新的思路,尤其利用纳米载体负载声敏剂,可以解决有机声敏剂水溶性差、容易被提前释放等问题,实现药物靶向作用,为声动力治疗与其他疗法结合提供平台,进一步发挥声动力治疗疗效。因此,该文总结了纳米载体负载有机声敏剂用于声动力治疗的相关研究,着重介绍纳米载体在声动力治疗中的研究进展及相关机理,指出现存问题,最终希望可以总结出用于声动力治疗的纳米载体的共性,为今后研究提供帮助。 相似文献