Application of the z-transform to composite materials

Applications of the z-transform were made earlier to interfacial electron transfer involving semi-infinite solids, e.g., semiconductor/liquid and metal/liquid interfaces and scanning tunneling microscopy. It is shown how the method is readily adapted to treat composite materials, such as solid/solid interfaces or "molecular wire"/solid interfaces

Pressure effects on bimolecular recombination and unimolecular dissociation reactions

The treatment of pressure effects on bimolecular recombinations and unimolecular dissociations is discussed. The analysis of recombination and dissociation reactions is made by showing how the nonequilibrium energy (E) and angular momentum (J)-dependent steady-state population distribution functions for the two reactions are related to each other and to the equilibrium population distribution function at the given E and J. As a special case a strong collision model is then used for the collisional rotational angular momentum transfer, and a ladder model for the collisional energy transfer. An analytical result is obtained for states below the dissociation threshold. The extension to recombinations with two exit channels is described, for application to ozone formation and isotopic effects

On the theory of electron transfer reactions at semiconductor/liquid interfaces. II. A free electron model

Electron transfer reactions at semiconductor/liquid interfaces are studied using the Fermi Golden rule and a free electron model for the semiconductor and the redox molecule. Bardeen's method is adapted to calculate the coupling matrix element between the molecular and semiconductor electronic states where the effective electron mass in the semiconductor need not equal the actual electron mass. The calculated maximum electron transfer rate constants are compared with the experimental results as well as with the theoretical results obtained in Part I using tight-binding calculations. The results, which are analytic for an s-electron in the redox agent and reduced to a quadrature for pz- and dz2-electrons, add to the insight of the earlier calculations

An approximate theory of the ozone isotopic effects: Rate constant ratios and pressure dependence

The isotopic effects in ozone recombination reactions at low pressures are studied using an approximate theory which yields simple analytic expressions for the individual rate constant ratios, observed under “unscrambled” conditions. It is shown that the rate constant ratio between the two competing channels XYZ-->X+YZ and XYZ-->XY+Z is mainly determined by the difference of the zero-point energies of diatomic molecules YZ and XY and by the efficiency of the deactivation of the newly formed excited ozone molecules, whereas the mass-independent fractionation depends on a “nonstatistical” symmetry factor eta and the collisional deactivation efficiency. Formulas for the pressure effects on the enrichment and on the rate constant ratios are obtained, and the calculated results are compared with experiments and more exact calculations. In all cases, ratios of isotope rates and the pressure dependence of enrichments, the agreement is good. While the initial focus was on isotope effects in the formation of O3, predictions are made for isotope effects on ratios of rate constants in other reactions such as O+CO-->CO2, O+NO-->NO2, and O+SO-->SO2

A theoretical study of ozone isotopic effects using a modified ab initio potential energy surface

A modified ab initio potential energy surface (PES) is used for calculations of ozone recombination and isotopic exchange rate constants. The calculated low-pressure isotopic effects on the ozone formation reaction are consistent with the experimental results and with the theoretical results obtained earlier [J. Chem. Phys. 116, 137 (2002)]. They are thereby relatively insensitive to the properties of these PES. The topics discussed include the dependence of the calculated low-pressure recombination rate constant on the hindered-rotor PES, the role of the asymmetry of the potential for a general X + YZ reaction (Y[not-equal]Z), and the partitioning to form each of the two recombination products: XYZ and XZY

Different intermediate water cluster with distinct nucleation dynamics among mono layer ice nucleation

Recent first-principle calculations unveiled a distinctive dynamic behavior in water molecule rotation during the melting process of highly confined water, indicating a notable time-scale separation in diffusion. In this short paper, we conducted molecular dynamics (MD) simulations to explore the rotation dynamics during the mono-layer ice nucleation process to investigate the possible intermediate states characterized by the differences in rotation of water molecules. Our study reveals two types of ice clusters with similar ice geometric structure but possess distinctly different rotational behaviors. In terms of molecular rotation, one type cluster is ice like (ILC) and can be regarded as small ice nuclei while the other is supercooled liquid water like (SCC). We found distinct nucleation pathways, thermodynamic properties, and phase transition dynamics to associate with these intermediate clusters, which yielded an unexpectedly complex picture of mono-layer ice nucleation.Comment: 12 pages, 5 figure

Data-driven Job Search Engine Using Skills and Company Attribute Filters

According to a report online, more than 200 million unique users search for jobs online every month. This incredibly large and fast growing demand has enticed software giants such as Google and Facebook to enter this space, which was previously dominated by companies such as LinkedIn, Indeed and CareerBuilder. Recently, Google released their "AI-powered Jobs Search Engine", "Google For Jobs" while Facebook released "Facebook Jobs" within their platform. These current job search engines and platforms allow users to search for jobs based on general narrow filters such as job title, date posted, experience level, company and salary. However, they have severely limited filters relating to skill sets such as C++, Python, and Java and company related attributes such as employee size, revenue, technographics and micro-industries. These specialized filters can help applicants and companies connect at a very personalized, relevant and deeper level. In this paper we present a framework that provides an end-to-end "Data-driven Jobs Search Engine". In addition, users can also receive potential contacts of recruiters and senior positions for connection and networking opportunities. The high level implementation of the framework is described as follows: 1) Collect job postings data in the United States, 2) Extract meaningful tokens from the postings data using ETL pipelines, 3) Normalize the data set to link company names to their specific company websites, 4) Extract and ranking the skill sets, 5) Link the company names and websites to their respective company level attributes with the EVERSTRING Company API, 6) Run user-specific search queries on the database to identify relevant job postings and 7) Rank the job search results. This framework offers a highly customizable and highly targeted search experience for end users.Comment: 8 pages, 10 figures, ICDM 201

Survey on the Overwintering of Syrphids in Changbai Mountains and Experiments on Artificial Protection of the Overwintering Syrphid Flies

Originating text in Chinese.Citation: Gao, Junfeng, Zhang, Guangxin, Qin, Yongchun, Yu, Kai, Li, Minghai, Qin, Yi. (1993). Survey on the Overwintering of Syrphids in Changbai Mountains and Experiments on Artificial Protection of the Overwintering Syrphid Flies. Chinese Journal of Biological Control, 9(3), 142-144

Broadband high efficiency active integrated antenna

Active integrated antenna (MA) is a very popular topic of research during recent decades. This is mostly due to its advantages, such as compact size, multiple functions and low cost, etc. The MA system can be regarded as an active microwave circuit which the output or input port is free space instead of a conventional 50-ohm interface. The major drawbacks of the conventional MA include narrow bandwidth, low efficiency, etc. An experimental investigation on broadband slot-coupled antenna is carried out, which results an impedance bandwidth of 50 % is achieved by both a ring slot- coupled and square ring slot-coupled patch antenna. An improved design technique for broadband class-E power amplifier (PA) design, based on the theoretical analysis done by Mader [2], is introduced to calculate the circuit parameters. The technique is applied to a RF microwave class-E power amplifier design (PA) that results a bandwidth of 12 % power added efficiency (PAE) greater than 60 % is achieved. The aim of this work is to design broadband high efficiency linearly polarized (LP) and circularly polarized (CP) MA and arrays that will be useful for mobile communication system. The MA does not need conventional matching network between the amplifier and the antenna, because the antenna serves as both a harmonics-tuning network and a radiator. A novel high efficiency broadband LP MA is demonstrated using a ring slot-coupled patch antenna with a class-E PA. It exhibits a PAE over 50 % within a 14.6 % bandwidth. For the first time, a high efficiency broadband CP MA is designed using a class-E PA integrated with a broadband CP antenna. The CP AIA achieves a PAE over 50 % within a 14 % bandwidth. The axial ratio of the CP MA is below 3 dB over a 9 % bandwidth. For further improve the performance, a novel L-shaped slot-coupled broadband CP MA is employed in a 2x2 array. The array consists of four sequentially rotated broadband CP antenna elements with an element spacing of half a free space wavelength. The antenna was designed to operate in the 3G band around 2 GHz. A bandwidth of 22.7 % PAE greater than 50 % is achieved together with a peak PAE of 71.35%. A bandwidth of 27 % axial ratio below 3 dB is resulted.EThOS - Electronic Theses Online ServiceGBUnited Kingdo