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排序方式: 共有636条查询结果,搜索用时 15 毫秒
61.
J Rupright A Singh H Stonnington W Voss M Feldman J Hewitt C Kapila 《Canadian Metallurgical Quarterly》1997,11(1):49-57
Murine embryonic stem (ES) cells have been a useful model system for the study of various aspects of hematopoietic differentiation. Because we had observed a sharp peak of expression of the receptor tyrosine phosphatase gamma (Ptp gamma) gene between 14 and 18 days of ES-derived embryoid body differentiation, we investigated the effect of perturbation of expression of the Ptp gamma gene on ES cell differentiation, first by analyzing the effect of Ptp gamma overexpression. The murine full-length Ptp gamma cDNA in an expression vector was transfected into ES-D3 cells and stably transfected clones were isolated. Ptp gamma was expressed as an approximately 230-kD cell surface protein, and differentiating ES clones that overexpressed Ptp gamma gave rise to a normal number of hematopoietic colonies, approximately 1 CFU per 100 cells. There was, however, a significant increase of expression of early hematopoietic markers in colonies from Ptp gamma overexpressing ES cells. To confirm that the pertubation of hematopoietic differentiation was a result of Ptp gamma overexpression, we isolated ES stem cell clones expressing Ptp gamma antisense constructs and assayed embryoid bodies for the presence of hematopoietic precursors. We observed a complete absence of methylcellulose colonies, indicating absence of hematopoietic lineages. Results of these experiments point to an essential role for Ptp gamma in hematopoietic differentiation. 相似文献
62.
Suman Dasgupta Dipak Sengupta 《International journal for numerical methods in engineering》1990,30(3):419-430
A new formulation of an eighteen-degrees-of-freedom higher-order triangular plate bending element using triangular area co-ordinates is presented. The displacement function w is taken as the complete fifth-order polynomial in area co-ordinates. The normal slope along an edge of the triangle is constrained to vary cubically. The twenty-one constants are expressed explicity in terms of eighteen degrees of freedom. The element stiffness matrix is expressed as a product of component matrices for which explicit expressions are developed and presented. No numerical inversion or integration is necessary. The formulation is expected to be useful specially for microcomputers. 相似文献
63.
Spatially homogeneous thermal explosions governed by a three-step chain-branching kinetic model are described in the asymptotic
limit of large activation energy for a range of chain-branching cross-over temperatures. The model consists of a sequence
of chain-initiation, chain-branching and chain-termination steps. Temperature-sensitive Arrhenius kinetics is employed for
the initiation and branching steps, while the termination step has a temperature-independent rate. Marked distinctions in
structure arise as the magnitude of the chain-branching cross-over temperature is increased relative to the initial system
temperature. Attention is focused on the regime where the chain-branching cross-over temperature is close to the initial system
temperature. Results are also obtained for the fast and slow explosion limits where the two temperatures are not close.
An erratum to this article can be found at 相似文献
64.
Suman Roy Choudhury Suhasini Roy Choudhury J. Rangarajan R. Rengaswamy 《Journal of power sources》2005,140(2):274-279
Transient state response analysis of phosphoric acid fuel cell (PAFC) cathode is important to understand various competitive processes like diffusion, reaction and product back diffusion occurring at various layers of the composite cathode. A two-dimensional unsteady state model for simulating PAFC cathode is developed as an extension of the previously developed steady-state model [S. Roy Choudhury, M.B. Deshmukh, R. Rengaswamy, A two-dimensional steady-state model for phosphoric acid fuel cells (PAFC), J. Power sources 112 (2002) 137–152]. The transient model is solved to study the impact of various parameters such as Tafel slope, diffusivity etc on the step response of the fuel cell. The effect of partial pressure variation in bulk gas for large sized PAFC cathode is also analysed. Trend analysis based on the model output is also experimentally verified using a small unit cell setup. The effect of various parameters on the settling time of the cathode, as revealed in this study, suggests possible development of a diagnostic tool employing such transient model. 相似文献
65.
V.P. Sakthivel M. Suman P.D. Sathya 《Energy Sources, Part B: Economics, Planning, and Policy》2020,15(6):351-382
ABSTRACT This paper bestows a new swarm intelligence approach, Squirrel Search Algorithm (SSA) to solve Economic Load Dispatch (ELD) of the thermal unit by addressing the valve point loading effects and multiple fuel options. SSA inspires the foraging behavior of squirrels which is based on dynamic jumping and gliding strategies. The main intention of the ELD problem is to minimize the total generation cost of units while assuring various system constraints. Renovate strategy and selection rules are used in the SSA algorithm to handle the constraints appropriately. The practicability of the proposed algorithm is tested on six different power test systems having different sizes and intricacies. Simulation results ascertain that the proposed SSA approach outperforms the other existing heuristic optimization techniques in terms of solution quality, robustness, and computational efficiency. Consequently, the proposed SSA can be an efficient approach for solving the ELD problems with valve point loading impacts and multi-fuel options. 相似文献
66.
Ugur Malayoglu Kadir C. TekinUfuk Malayoglu Suman Shrestha 《Materials Science and Engineering: A》2011,528(24):7451-7460
A ceramic coating on AA6082 aluminum alloy prepared by plasma electrolytic oxidation (PEO) has been studied and compared against a sulphuric acid hard-anodized coating on the same alloy. Surface morphology and microstructures of the coatings have been examined by scanning electron microscopy. X-ray diffraction is used to determine the phase composition of the coatings. The adhesion strength of the coatings has been evaluated using a scratch test method. The coating's mechanical properties such elastic modulus and hardness data have been generated using a dynamic ultra-microhardness tester. Sliding wear tests with different loading rates are performed on the coatings in order to assess their wear resistance. Test results show that the PEO treated samples exhibit significantly better mechanical properties compared to hard anodized samples. The elastic modulus and hardness of the PEO coating are 2-3 times greater than of the hard anodized coating and subsequently, an improved wear resistance of the PEO coating has been achieved. The mechanical properties of the coatings and their relations to their tribological performance are discussed. 相似文献
67.
Do‐Yeon Kim Suman Sinha‐Ray Jung‐Jae Park Jong‐Gun Lee You‐Hong Cha Sang‐Hoon Bae Jong‐Hyun Ahn Yong Chae Jung Soo Min Kim Alexander L. Yarin Sam S. Yoon 《Advanced functional materials》2014,24(31):4986-4995
The industrial scale application of graphene and other functional materials in the field of electronics has been limited by inherent defects, and the lack of simple deposition methods. A simple spray deposition method is developed that uses a supersonic air jet for a commercially available reduced graphene oxide (r‐GO) suspension. The r‐GO flakes are used as received, which are pre‐annealed and pre‐hydrazine‐treated, and do not undergo any post‐treatment. A part of the considerable kinetic energy of the r‐GO flakes entrained by the supersonic jet is used in stretching the flakes upon impact with the substrate. The resulting “frozen elastic strains” heal the defects (topological defects, namely Stone‐Wales defect and C2 vacancies) in the r‐GO flakes, which is reflected in the reduced ratio of the intensities of the D and G bands in the deposited film. The defects can also be regenerated by annealing. 相似文献
68.
T. R. Vijaybabu T. Ramesh Suman Pandipati Sujit Mishra G Sridevi C Pradeep Raja Rhoda Afriyie Mensah Oisik Das Manjusri Misra Amar Mohanty Karthik Babu NB 《大分子材料与工程》2023,308(7):2300001
The lifespan and the performance of flexible electronic devices and components are affected by the large accumulation of heat, and this problem must be addressed by thermally conductive polymer composite films. Therefore, the need for the development of high thermal conductivity nanocomposites has a strong role in various applications. In this article, the effect of different particle reinforcements such as single and hybrid form, coated and uncoated particles, and chemically treated particles on the thermal conductivity of various polymers are reviewed and the mechanism behind the improvement of the required properties are discussed. Furthermore, the role of manufacturing processes such as injection molding, compression molding, and 3D printing techniques in the production of high thermal conductivity polymer composites is detailed. Finally, the potential for future research is discussed, which can help researchers to work on the thermal properties enhancement for polymeric materials. 相似文献
69.
AI Brain C Verghese EV Addy A Kapila J Brimacombe 《Canadian Metallurgical Quarterly》1997,79(6):704-709
To determine the effect of anterior cruciate ligament (ACL) reconstruction on symptoms of pain and instability in patients with chronic ACL insufficiency who had previously undergone meniscectomy, we reviewed a series of 21 symptomatic, previously meniscectomized patients with chronic ACL deficiency (average age, 31 years). Arthroscopically assisted intra-articular ACL reconstruction using a middle, one-third patella-tendon autograft was performed in all cases. All patients had radiographic evidence of degenerative changes before ACL reconstruction. The average time from meniscectomy to ACL reconstruction was 6.6 years. Preoperative and postoperative range of motion, stability, and subjective evaluations were compared. Follow-up averaged 37.4 months (range, 24 to 67 months). Physical examination and postoperative KT-1000 side-to-side measurements revealed three patients (14%) with pathological ligament laxity. One patient had a 2+ Lachman, a 2+ pivot shift, and > 5 mm difference on KT-1000 maximum manual test, and two patients had a 1+ Lachman and a 1+ pivot shift. Range of motion measurements taken at follow-up were not significantly different from preoperative measurements (extension, P = .14; flexion, P = .46). Subjectively, all items on a panel of 15 visual analog scales were improved, but intensity of pain and instability were significantly improved after statistical analysis (P < .05). This review suggests that symptoms of pain and instability in patients with chronic ACL deficiency who have previously undergone meniscectomy can be improved by ACL reconstruction if objective stability is obtained. 相似文献
70.
ET Creagan KM Rowland VJ Suman CG Kardinal RF Marschke RS Marks WJ Maples 《Canadian Metallurgical Quarterly》1997,20(5):490-492
Adoptive immunotherapy (AI) with interleukin-2 (IL-2) and lymphokine-activated killer cells (LAK) is an antineoplastic modality in which immune-activated cells are administered to a host with advanced cancer in an attempt to mediate tumor regression. Levamisole (LEV), an immune stimulant, has been suggested to have therapeutic effectiveness in a variety of cancers. After a phase I trial of recombinant IL-2 plus LEV, a phase II trial of this combination was conducted in patients with advanced malignant melanoma. Nineteen patients were entered in the trial. They received IL-2 at 3 x 10(6) U/m2 subcutaneously daily x 5 plus LEV 50 mg/ m2 orally three times daily (p.o. t.i.d.) x 5. Patients were reevaluated at four-week intervals. None of the patients achieved a partial or complete regression (PR, CR). The median time to treatment failure (refusal, progression, or off study due to toxicity) was 56 days. Grade IV toxicities included vomiting (3 patients), lethargy (1 patient), and musculoskellar pain (1 patient). This regimen is not recommended for further testing in patients with advanced malignant melanoma. 相似文献