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Natural Convection Heat Transfer From a Hot Rectangular and a Square Corrugated Plate to a Cold Flat Plate

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Journal of Thermal Science 2000年第3期9卷 243-248页

作者： m. A. R. Akhanda F. m. chowdhury (Department of mechanical Engineering, Bangladesh University of Engineering and Technology (BUET), Dhaka- 1000, Bangladesh) Department of mechanical Engineering Bangladesh University of Engineering and Technology (BUET) Bangladesh

Experimental study of natural convection heat transfer across air layers bounded by a lower hot rectangular and a square corrugated plates to an upper cold flat plate has been carried out. The surroundings of this space are adiabatic. The effect of the angle of inclination, the aspect ratio, the temperature potential and the Rayleigh number on average heat transfer coefficients are investigated within a range of 0°≤75°,, 2.33≤A≤6.33, 10°≤T ≤35°, and 3.29xl04≤RaL≤ 2.29x106. The developed correlation predicts well the experimental data within an error of ±15%.

关键词： natural convection heat transfer corrugation.

Systems Biology of Plant-microbiome Interactions

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molecular Plant 2019年第6期12卷 804-821页

作者： Patricia A.Rodriguez michael Rothballer Soumitra Paul chowdhury Thomas Nussbaumer Caroline Gutjahr Pascal Falter-Braun Institute of Network Biology (INET) Helmholtz Zentrum Munchen German Research Center for Environmental Health Munich Germany Institute of Environmental medicine (IEm) UNIKA-T Technical University of Munich Augsburg Germany Plant Genetics TUM School of Life Science Weihenstephan Technical University of Munich (TUM) Freising Germany microbe-Host Interactions Faculty of Biology Ludwig-Maximilians-Universitat (LMU) Mijnchen Munich Germany

In natural environments,plants are exposed to diverse microbiota that they interact with in complex *** plant-pathogen interactions have been intensely studied to understand defense mechanisms in plants,many microbes and microbial communities can have substantial beneficial effects on their plant *** beneficial effects include improved acquisition of nutrients,accelerated growth,resilience against pathogens,and improved resistance against abiotic stress conditions such as heat,drought,and ***,the beneficial effects of bacterial strains or consortia on their host are often cultivar and species specific,posing an obstacle to their general ***,many of the signals that trigger plant immune responses are molecularly highly similar and often identical in pathogenic and beneficial ***,it is unclear what determines the outcome of a particular microbe-host interaction and which factors enable plants to distinguish beneficials from *** unravel the complex network of genetic,microbial,and metabolic interactions,including the signaling events mediating microbe-host interactions,comprehensive quantitative systems biology approaches will be needed.

关键词： plant systems biology plant microbiome microbial communities SynComs microbe-host interactions

Organic Amendments Improve Plant morpho-Physiology and Antioxidant metabolism in mitigating Drought Stress in Bread Wheat(Triticum aestivum L.)

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Phyton-International Journal of Experimental Botany 2022年第9期91卷 1959-1972页

作者： Taufika Islam Anee md.Nur Nabi Islam mohamed m.Hassan Abdul Awal chowdhury masud md.mahabub Alam mirza Hasanuzzaman Department of Agronomy Faculty of AgricultureSher-e-Bangla Agricultural UniversityDhaka1207Bangladesh Department of Biology College of ScienceTaif UniversityTaif21944Saudi Arabia

Due to the unpredictable climate change,drought stress is being considered as one of the major threats to crop ***(Triticum aestivum *** Gom-26)being a dry season crop frequently faces scarcity of water and results in a lower ***,this experiment aims to explore the role of different organic amendments(OAs)in mitigating drought stress-induced *** pot experiment consisted of different organic amendments ***,vermicompost and poultry manure@0.09 kg m^(−2)soil,biochar@2.5%w/w soil and chitosan@1%w/w soil which was imposed on the plants grown under both well-watered and drought *** showed that drought stress reduced plant height(15%),SPAD value(16%),relative water content(13%),number of spikelet spike^(−1)(17%),number of grains spike^(−1)(12%),and 100-grain weight(18%).Organic amendments act as a protectant and reduce drought stress-induced damages by enhancing the morpho-physiological and yield *** enhanced SPAD value by 18%,number of spikelets spike^(−1)by 20%,number of grains spike^(−1)by 17%,whereas poultry manure increased plant height by 16%under drought condition compared to control *** other OAs applied,vermicompost was proved to be capable of reducing the higher lipid peroxidation and proline content raised by drought *** stress-induced increment of catalase,ascorbate peroxidase and glutathione reductase activities were also efficiently modulated by the organic amendment *** present study concluded that OAs play significant roles in alleviating drought stressinduced damages by improving the morpho-physiological attributes and among the different types of OAs used vermicompost performed better which in addition ceased the production of reactive oxygen species.

关键词： Antioxidant defense biochar cereal crop chitosan compost poultry manure reactive oxygen species vermicompost

Divergence Free QED Lagrangian in (2 + 1)-Dimensional Space-Time with Three Different Regularization Prescriptions

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Journal of Applied mathematics and Physics 2018年第10期6卷 2067-2086页

作者： m. Forkan m. Abul mansur chowdhury Department of mathematics University of Chittagong Chittagong Bangladesh JNI Research Centre for mathematical and Physical Sciences University of Chittagong Chittagong Bangladesh

Quantum field theory can be understood through gauge theories. It is already established that the gauge theories can be studied either perturbatively or non-perturbatively. Perturbative means using Feynman diagrams and non-perturbative means using Path-integral method. Operator regularization (OR) is one of the exceptional methods to study gauge theories because of its two-fold prescriptions. That means in OR two types of prescriptions have been introduced, which gives us the opportunity to check the result in self consistent way. In an earlier paper, we have evaluated basic QED loop diagrams in (3 + 1) dimensions using the both methods of OR and Dimensional regularization (DR). Then all three results have been compared. It is seen that the finite part of the result is almost same. In this paper, we are interested to evaluate the same basic loop diagrams in (2 + 1) space-time dimensions, because of two reasons: the main reason in (2 + 1) space-time dimensions, these loops diagrams are finite, on other hand, there are divergences in (3 + 1) space-time dimensions and the other reason is to see validity of using OR to evaluate Feynman loop diagrams in all dimensions. Here we have used both prescriptions of OR and DR to evaluate the basic loop diagrams and compared the results. Interestingly the results are almost same in all cases.

关键词： Operator Regularization Dimensional Regularization Feynman Diagrams in QED Path-Integral method Background Field Quantization and Generating Functional

Patterns of tree buttressing at Lawachara National Park, Bangladesh

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Journal of Forestry Research 2012年第3期23卷 461-466页

作者： md. A bu Hanifa mehedi Chandan Kundu md. Qumruzzaman chowdhury Department of Forestry and Environmental Science Shahjalal University of Science and TechnologySylhet-3114Bangladesh

We describe patterns of buttress formation and development in eleven tree species at Lawachara National Park, Bangladesh. Forty-five percent of trees of these 11 species had buttresses. Artocarpus chaplasha Roxb. showed maximum （87%） buttress formation, whereas Alstonia scholaris （L.） R. Br. did not show any buttress. Buttresses were recorded in 20%-40% of trees of six species and 40%-60% of trees in three species. mean length and height of buttress varied among the species and ranged from 0.37-4.37 m and 0.71-2.13 m, respectively. Buttress height, mean buttress length, total buttress length, and total length plus length of secondaries increased with DBH （diameter at breast height） and tree height. Buttress number did not increase with DBH or tree height. Under-storey and mid-canopy trees produced less developed buttresses than did emergent trees （p〈0.01）. Wood density showed moderate effects on buttress characters （p〈0.05）, while the slope of the land did not. Canopy category was a primary regulating factor for tree buttressing, suggesting that buttresses are mechanical adaptations of trees to counter physical stresses.

关键词： buttresses tree architecture canopy category slope of the ground wood density

Design of current mirror integration ROIC for snapshot mode operation

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Journal of Semiconductors 2016年第10期37卷 68-74页

作者： Hari Shanker Gupta A S Kiran Kumar m.Shojaei Baghini Subhananda Chakrabarti Sanjeev mehta Arup Roy chowdhury Dinesh K Sharma Indian Institute of Technology Bombay Mumbai India Space Applications Centre Jodhpur Tekra Ahmedabad India

Current mirror integration（CmI） read out integrated circuit（ROIC） topology provides a low input impedance to photo-detectors and provides large injection efficiency, large charge handling capacity and snapshot mode operation without in-pixel opamps. The ROIC described in this paper has been implemented with a modified current mirror circuit, with matched PmOS pairs for detector input stage and its biasing. The readout circuit has been designed for 30×30μm^2 pixel size, 4×4 array size, variable frame rate, 5 me charga pixel per second（mpps）.Experimental performance of the test chip has achieved 15 me charge handling capacity, a high dynamic range of83 dB, 99.8% linearity and 99.96% injection efficiency. The ROIC design has been fabricated in 3.3 V 1P6 mUmC180 nm CmOS process and tested up to 5 mHz pixel rate at room and at cryogenic temperature.

关键词： pixel pitch readout integrated circuit (ROIC) cryogenics snapshot FPA IR detectors

Zero Truncated Bivariate Poisson model: marginal-Conditional modeling Approach with an Application to Traffic Accident Data

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Applied mathematics 2016年第14期7卷 1589-1598页

作者： Rafiqul I. chowdhury m. Ataharul Islam ISRT University of Dhaka Dhaka Bangladesh Department of Applied Statistics East West University Dhaka Bangladesh

A new covariate dependent zero-truncated bivariate Poisson model is proposed in this paper employing generalized linear model. A marginal-conditional approach is used to show the bivariate model. The proposed model with estimation procedure and tests for goodness-of-fit and under (or over) dispersion are shown and applied to road safety data. Two correlated outcome variables considered in this study are number of cars involved in an accident and number of casualties for given number of cars.

关键词： Bivariate Poisson Conditional model Generalized Linear model marginal model Road Safety Data Zero-Truncated

Design of a Porous Cored Hexagonal Photonic Crystal Fiber Based Optical Sensor With High Relative Sensitivity for Lower Operating Wavelength

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Photonic Sensors 2017年第1期7卷 55-65页

作者： Shuvo SEN Sawrab chowdhury Kawsar AHmED Sayed ASADUZZAmAN Department of Information and Communication Technology Mawlana Bhashani Science and Technology UniversitySantosh Tangail-1902 Bangladesh Group of Biophotomatix Bangladesh

In this article, highly sensitive and low confinement loss enriching micro structured photonic crystal fiber （PCF） has been suggested as an optical sensor. The proposed PCF is porous cored hexagonal （P-HPCF） where cladding contains five layers with circular air holes and core vicinity is formed by two layered elliptical air holes. Two fundamental propagation characteristics such as the relative sensitivity and confinement loss of the proposed P-HPCF have been numerically scrutinized by the full vectorial finite element method （FEm） simulation procedure. The optimized values are modified with different geometrical parameters like diameters of circular or elliptical air holes, pitches of the core, and cladding region over a spacious assortment of wavelength from 0.8 ktm to 1.8 -m. All pretending results exhibit that the relative sensitivity is enlarged according to decrement of wavelength of the transmission band （O＋E＋S＋C＋L＋U）. In addition, all useable liquids reveal the maximum sensitivity of 57.00%, 57.18%, and 57.27% for n=1.33, 1.354, and 1.366 respectively by lower band. moreover, effective area, nonlinear coefficient, frequency, propagation constant, total electric energy, total magnetic energy, and wave number in free space of the proposed P-HPCF have been reported recently.

关键词： Optical sensor relative sensitivity porous core PCF confinement loss transmission band effective area

Investigation of in vivo neuropharmacological effect of Alpinia nigra leaf extract

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Asian Pacific Journal of Tropical Biomedicine 2014年第2期4卷 137-142页

作者： Farjana Sharmen Adnan mannan md.mominur Rahman md.Ashraf Uddin chowdhury muhammad Erfan Uddin A.m.Abu Ahmed Department of Genetic Engineering and Biotechnology University of ChittagongChittagong-4331Bangladesh Department of Pharmacy International Islamic University ChittagongChittagongBangladesh

Objective:To analyze in vivo neuro-pharmacological effects of Alpinia nigra as anxiety is a particular form of behavioral inhibition that occurs in response to novel environmental ***:In present study,the extract of Alpinia nigra was evaluated for its central nervous system depressant effect using mice behavioral models,such as hole cross,open field and thiopental sodium induced sleeping time tests for its sedative properties and an elevated plusmaze test for its anxiolytic potential,***:In anxiolytic study,the extract displayed increased percentage of entry into open arm ut the dose of 400 and 200 mg/*** extract produced a significant(Pmpared to sodium thiopental at both doses(200 and400 mg/kg).The extract t.200 and 400 mg/kg) also showed a dose-dependent suppression of motor activity and exploratory activity of the mice in both open field and hole cross ***:This study demonstrates that the treated extract has significant central nervous system depressant *** studies on active constituent of the extract can provide approaches for therapeutic intervention.

关键词： Sedative Elevated plus maze Anxiolytic Antidepressant activity Alpinia nigra