Adhesion between atomically pure metallic surfaces Final report

Metallic adhesion from compression loads resulting in plastic deformatio

Adhesion between atomically pure metallic surfaces, part 4 Semiannual report

Adhesion between atomically pure metal surface

Adhesion between automatically pure metallic surfaces, part 4 Semiannual report

Contact resistance measurements to determine adhesion between atomically pure metallic surface

The economic development of Shanghai, 1842-1910

Thesis (M.A.)--Boston UniversityDuring the 19th century, foreign colonization had gradually extended to China. Due to the nearness to the other European colonies in Asia, the southern coast of China including Canton and Fukien naturally became the first ones to establish trading relations with the foreign fleets. However, the restriction of trade at Canton made the foreign merchants find a new out let in the China market. The outbreak of the Opium War in 1842 virtually showed the eagerness of the British to establish permanent trading foothold and to set a new influence over China trade. Under the Treaty of Nangking signed in 1842, Shanghai was declared as an open port, and opened freely to foreign trade. After the port was opened, the British Settlement was immediately founded for the exclusive use of the British merchants. Such exclusive priviledges was envied by other foreign powers, and the open-door policy based on equal treatment was thus demanded. Soon afterwards, other foreign countries followed suit, in which the Americans and the French were both establishing Settlements for their own. Due to the advantageous location of the foreign Settlements and the security given by the foreign powers, the development in the Settlements was greatly enhanced after the opening of the port. Hand in hand, with the economic development or Shanghai, the British and other foreign powers had their base interests in developing Shanghai in various aspects as to increase their trade and commerce to a further extent. The various Land Regulations with their several revisions safeguarded the foreign interests in Shanghai and also rounded the administrating policies. The Municipal Council was officially inaugurated in 1854 which administered most of the Municipal affairs as well as commercial and financial interests. The Shanghai Municipal Council had contributed a great deal in the domestic developments of the Settlements such as the building of bridges, construction or roads, sanitation and tax system. In addition to public works the Consul had also helped a great deal in establishing various public utilities. Although some of the utilities were founded by individual companies, but without the aid or the Municipal Council these works could not be carried out favorably. There were a number or utilities formed within this seventy years of opening or port such as the "Shanghai Water Works", the "Shanghai Gas Company", the "Shanghai Electric Company", and the "Brush Electric Tramway Company." These companies were established successively in accordance with the needs of the growing population in Shanghai. In order to comply with the need of growing trade and industries, many wharves and warehouses were built for lading and storing merchandise. The Woosung Railroad was first constructed in 1876 to facilitate the transportation between Woosung wharves and Shanghai. Similarly, the Shanghai Nangking Railroad was built in 1905. In regard to trade and commerce, we may say that Shanghai surpassed Canton shortly after the opening of port, due to a better location and better trade method in Shanghai. One significant feature of the early trade is that most of the commerce was carried under a monopoly-like system. Several large commercial houses were organized to control the Shanghai trade, under the management of foreign merchants, mostly British. The several most well known and prominent commercial houses established within this seventy years were the "Hongkong and Shanghai Banking Corporation", the "Shanghai Stearn Navigation Company," the "Oriental Banking Corporation," and the "China Merchants Steam Navigation Company." The trade volume of Shanghai increased enormously during the period from 1840 to 1910. The figures run roughly 3.5 million taels in 1843 to 37 million taels in 1865, to 167 million taels in 1892, to 118 million taels in 1901, and to 169 million taels in 191O, respectively. Among the various items of foreign trade, opium and cotton were the major items of imports which amounted to roughly 75% of total imports annually. Tea and silk represented the major items of exports which constituted over 80% of the total exports annually. However, it must be noted that most of the foreign trade within this period from 1840 to 191O was largely handled by the British merchants. In 1895 the industrial developments were greatly stimulated in Shanghai. It was caused by the Treaty of Shinomosheki signed between Japan and China, which gave special priviledges to foreign countries to start manufacturing industries in Shanghai. Many foreign merchants took this opnortunity and a number of foreign owned factories made their appearance. Various developments of industries were established. Among them most important ones were the Textile industries, Metal and Machineries industries, Flour Mill industreis, Chemical works, and Ship building industries. However, the industrial developments did effect the life of the Settlement greatly. The result was two-fold. On one hand it increased the production in the Settlements and tend to raise the standard of living of people, but on the other hand, it gave birth to many evils which were harmful to workers such as the use of contract labor, child labor, and the use of poor physical plant. All these defects were due to the lack of industrial regulations which both the International Settlement and the French Concession had limited authority to regulate upon. As a whole, the significance of Shanghai to foreign powers had been based largely on these various economic factors. It had been the policy of the foreign powers to protect their capital investment, their trade, and their citizens, and at the same time to use the means of protection, armed forced, to gain further privileges from China. This was true since the beginning of the opening of port and has been true at various times since that date

Self-consistent determination of the perpendicular strain profile of implanted Si by analysis of x-ray rocking curves

Results of a determination of strain perpendicular to the surface and of the damage in (100) Si single crystals irradiated by 250-keV Ar+ ions at 77 K are presented. Double-crystal x-ray diffraction and dynamical x-ray diffraction theory are used. Trial strain and damage distributions were guided by transmission electron microscope observations and Monte Carlo simulation of ion energy deposition. The perpendicular strain and damage profiles, determined after sequentially removing thin layers of Ar+-implanted Si, were shown to be self-consistent, proving the uniqueness of the deconvolution. Agreement between calculated and experimental rocking curves is obtained with strain and damage distributions which closely follow the shape of the trim simulations from the maximum damage to the end of the ion range but fall off more rapidly than the simulation curve near the surface. Comparison of the trim simulation and the strain profile of Ar+-implanted Si reveals the importance of annealing during and after implantation and the role of complex defects in the final residual strain distribution

A COMPARISON OF DEMANDS FOR MEAT PRODUCTS IN THE PACIFIC RIM REGION

The Rotterdam model is used to obtain estimates of demand parameters for meat products in Taiwan, South Korea, and Japan. Unlike most previous studies of demand systems, the model takes into account simultaneous-equation bias which arises due to the endogeneity of total expenditure. Beef, pork, and chicken are separable from marine products for each Pacific Rim country. However, demand elasticities for beef, pork, and chicken are different among the various Pacific Rim nations. One may not then use the elasticity estimates of a particular country and apply them to other Pacific Rim markets.Demand and Price Analysis,

Influence of substrate temperature on lattice strain field and phase transition in MeV oxygen ion implanted GaAs crystals

A detailed study of the influence of substrate temperature on the radiation-induced lattice strain field and crystalline-to-amorphous (c-a) phase transition in MeV oxygen ion implanted GaAs crystals has been made using channeling Rutherford backscattering spectroscopy, secondary ion mass spectrometry, and the x-ray rocking curve technique. A comparison has been made between the cases of room temperature (RT) and low temperature (LT) (about 100 K) implantation. A strong in situ dynamic annealing process is found in RT implantation at a moderate beam current, resulting in a uniform positive strain field in the implanted layer. LT implantation introduces a freeze-in effect which impedes the recombination and diffusion of initial radiation-created lattice damage and defects, and in turn drives more efficiently the c-a transition as well as strain saturation and relaxation. The results are interpreted with a spike damage model in which the defect production process is described in terms of the competition between defect generation by nuclear spikes and defects diffusion and recombination stimulated by electronic spikes. It is also suggested that the excess population of vacancies and their complexes is responsible for lattice spacing expansion in ion-implanted GaAs crystals

Defect formation and diffusion mechanism in ion-assisted molecular-beam epitaxy

A simple moving boundary diffusion model has been used to characterize defect incorporation kinetics during ion-assisted molecular-beam epitaxy. The model permits analysis of the dependence of the final defect concentration on the growth rate, defect diffusivity, defect production range, and the shape of defect depth distribution. The results indicate a linear dependence of the final defect concentration on the ion-to-atom flux ratio which is in the growth-rate-limited regime of the model. Comparison between the model and the film strains measured by x-ray rocking curve analyses has been made and reveals that the thermal spike energy deposited by the bombarding ions during epitaxial growth has a significant effect on the apparent activation energy of the defect migration. A transition temperature above which the defect migration is thermally activated and below which the defect migration is cascade assisted can be defined. The experimentally observed temperature dependence of the defect concentration can be attributed to cascade-assisted diffusion of the defects. Comparison between the model and the multisite multiply activated migration model for low-energy dopant incorporation has also been made. The results show the similarity between the defect incorporation and dopant incorporation which gives a unified view of both processes

Genome-wide survey and expression analysis of the bHLH-PAS genes in the amphioxus Branchiostoma floridae reveal both conserved and diverged expression patterns between cephalochordates and vertebrates

BACKGROUND: The bHLH-PAS transcription factors are found in both protostomes and deuterostomes. They are involved in many developmental and physiological processes, including regional differentiation of the central nervous system, tube-formation, hypoxia signaling, aromatic hydrocarbon sensing, and circadian rhythm regulation. To understand the evolution of these genes in chordates, we analyzed the bHLH-PAS genes of the basal chordate amphioxus (Branchiostoma floridae). RESULTS: From the amphioxus draft genome database, we identified ten bHLH-PAS genes, nine of which could be assigned to known orthologous families. The tenth bHLH-PAS gene could not be assigned confidently to any known bHLH family; however, phylogenetic analysis clustered this gene with arthropod Met family genes and two spiralian bHLH-PAS-containing sequences, suggesting that they may share the same ancestry. We examined temporal and spatial expression patterns of these bHLH-PAS genes in developing amphioxus embryos. We found that BfArnt, BfNcoa, BfSim, and BfHifα were expressed in the central nervous system in patterns similar to those of their vertebrate homologs, suggesting that their functions may be conserved. By contrast, the amphioxus BfAhr and BfNpas4 had expression patterns distinct from those in vertebrates. These results imply that there were changes in gene regulation after the divergence of cephalochordates and vertebrates. CONCLUSIONS: We have identified ten bHLH-PAS genes from the amphioxus genome and determined the embryonic expression profiles for these genes. In addition to the nine currently recognized bHLH-PAS families, our survey suggests that the BfbHLHPAS-orphan gene along with arthropod Met genes and the newly identified spiralian bHLH-PAS-containing sequences represent an ancient group of genes that were lost in the vertebrate lineage. In a comparison with the expression patterns of the vertebrate bHLH-PAS paralogs, which are the result of whole-genome duplication, we found that although several members seem to retain conserved expression patterns during chordate evolution, many duplicated paralogs may have undergone subfunctionalization and neofunctionalization in the vertebrate lineage. In addition, our survey of amphioxus bHLH-PAS gene models from genome browser with experimentally verified cDNA sequences calls into question the accuracy of the current in silico gene annotation of the B. floridae genome

X-Ray Diffraction Determination of Stresses in Thin Films

This paper presents the methodology employed in the determination of the stress tensor for thin crystalline films using x-ray rocking curves. Use of the same equipment for the determination of the average stress in poly- or non-crystalline thin films attached to a crystalline substrate is also discussed. In this case the lattice curvature of the substrate is determined by measurement of the shift In the Bragg peak with lateral position in the substrate. Strains in single crystal layers may be measured using Bragg diffraction from the layers and from the substrate or a reference crystal, with the highest strain sensitivity of any known technique. The difference in Bragg angles for a strained and an unstrained crystal is related to the change in d spacing of the Bragg planes, and the elastic strain is related to this angular difference. The separation of two peaks on an x-ray rocking curve is generally not equal to the difference in Bragg angles of two diffracting crystals, so diffractometer measurements must be carefully Interpreted in order to obtain x-ray strains in crystalline films (x-ray strains are strains relative to the reference crystal). The unstrained d spacings of the film and the d spacings of the reference crystal must be known to obtain the elastic strains in the film, from which the stress tensor is determined