检索结果-南通市图书馆

Paleo-glacial reconstruction of the Thajwas glacier in the Kashmir Himalaya using 10Be cosmogenic radionuclide dating

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2022年第6期13卷 30-40页

作者： Omar Jaan Paul shakil Ahmad Romshoo Reyaz Ahmad Dar Pankaj Kumar Soumya Prakash Dhal Sundeep Chopra Department of Earth Sciences University of KashmirSrinagarIndia Islamic University of Science and Technology(IUST) KashmirIndia Inter-University Accelerator Centre(IUAC) New DelhiIndia Department of Geoinformatics University of KashmirSrinagarIndia

Quantitative glacial chronologies of past glaciations are sparse in the Himalaya, and mostly absent in the Kashmir Himalaya. We used cosmogenicBe exposure dating, and geomorphological mapping to reconstruct glacial advances of the Thajwas Glacier(TG) in the Great Himalayan Range of the Kashmir Himalaya. FromBe exposure dating of ten moraine boulders, four glacial stages with ages ~20.77 ±2.28 ka, ~11.46 ± 1.69 ka, ~9.12 ± 1.39 ka and ~4.19 ± 0.78 ka, were identified. The reconstructed cosmogenic radionuclide ages confirmed the global Last Glacial Maximum(g LGM), Younger Dryas, Early Holocene, and Neoglaciation episodes. As per area and volume change analyses, the TG has lost 51.1 km~2 of its area and a volume of 2.64 km~3 during the last 20.77 ± 2.28 ka. Overall, the results suggested that the TG has lost 64% of area and 73% of volume from the Last glacial maximum to Neoglaciation and about 85.74% and 87.67% of area and volume, respectively, from Neoglaciation to the present day. The equilibrium line altitude of the TG fluctuated from 4238 m a.s.l present to3365 m a.s.l during the g LGM(20.77 ± 2.28 ka). The significant cooling induced by a drop in mean ambient temperature resulted in a positive mass balance of the TG during the g LGM. Subsequently the melting accelerated due to the continuing rise of the global ambient temperature. Paleo-glacial history reconstruction of the Kashmir Himalaya, with its specific geomorphic and climatic setting, would help close the information gap about the chronology of past regional glacial episodes.

关键词： Glacier reconstruction Cosmogenic 10Be gLGM Kashmir Himalaya Equilibrium Line Altitude

Theoretical investigation of sulfur defects on structural, electronic,and elastic properties of ZnSe semiconductor

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2015年第7期24卷 365-370页

作者： muhammad Zafar Shabbir Ahmed M.shakil M.A.Choudhary K.Mahmood Simulation Laboratory Department of PhysicsThe Islamia University of Bahawalpur 63100Pakistan Department of Physics GC UniversityFaisalabad 68000Pakistan

The structural, electronic, and elastic properties of ZnSe1-xSx for the zinc blende structures have been studied by using the density functional theory. The calculations were performed using the plane wave pseudopotential method, as implemented in Quantum ESPRESSO. The exchange-correlation potential is treated with the local density approximation pz-LDA for these properties. Moreover, LDA＋U approximation is employed to treat the ＂d＂ orbital electrons properly. A comparative study of the band gap calculated within both LDA and LDA＋U schemes is presented. The analysis of results show considerable improvement in the calculation of band gap. The inclusion of compositional disorder increases the values of all elastic constants. In this study, it is found that elastic constants C11, C12, and C44 are mainly influenced by the compositional disorder. The obtained results are in good agreement with literature.

关键词： first principles calculations density functional theory II–VI semiconductors electronic and elastic properties

Streamflow response to shrinking glaciers under changing climate in the Lidder Valley,Kashmir Himalayas

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2018年第6期15卷 1241-1253页

作者： asif marazi shakil a.romshoo department of earth sciences university of kashmirSHnagar KashmirIndia

The study investigated the streamflow response to the shrinking cryosphere under changing climate in the Lidder valley, Upper Indus Basin(UIB), Kashmir Himalayas. We used a combination of multitemporal satellite data and topographic maps to evaluate the changes in area, length and volume of the glaciers from 1962 to 2013. A total of 37 glaciers from the Lidder valley, with an area of 39.76 km^2 in 1962 were selected for research in this study. It was observed that the glaciers in the valley have lost ~28.89 ±0.1% of the area and ~19.65 ±0.069% of the volume during the last 51 years, with variable interdecadal recession rates. Geomorphic and climatic influences on the shrinking glacier resources were studied. 30-years temperature records(1980-2010) in the study area showed a significant increasing trend in all the seasons. However, the total annual precipitation during the same period showed a nonsignificant decreasing trend except during the late summer months(July, August and September), when the increasing trend is significant. The depletion of glaciers has led to the significant depletion of the streamflows under the changing climate in the valley. Summer streamflows(1971-2012) have increased significantly till mid-nineties but decreased significantly thereafter, suggesting that the tipping point of streamflow peak, due to the enhanced glacier-melt contribution under increasing global temperatures, may have been already reached in the basin. The observed glacier recession and climate change patterns, if continued in future, would further deplete the streamflows with serious implications on water supplies for different uses in the region.

关键词：喜马拉雅山脉气候变化克什米尔流水量冰河流速山谷反应

Combination of mesenchymal stem cells and three-dimensional collagen scaffold preserves ventricular remodeling in rat myocardial infarction model

在线全文

学校读者我要写书评

暂无评论

World Journal of Stem Cells 2022年第8期14卷 633-657页

作者： Rida-e-Maria Qazi Irfan Khan Kanwal Haneef Tuba shakil Malick Nadia Naeem Waqas Ahmad Asmat Salim Sadia Mohsin Stem Cell Laboratory Dr.Panjwani Center for Molecular Medicine and Drug ResearchICCBSUniversity of KarachiKarachi 75270SindhPakistan Dr.Zafar H.Zaidi Center for Proteomics University of KarachiKarachi 75270SindhPakistan Dow Research Institute of Biotechnology and Biomedical Sciences(DRIBBS) Dow University of Health and SciencesOjha CampusKarachi 74200SindhPakistan Cardiovascular Research Center Lewis Katz School of MedicineTemple UniversityPhiladelphiaPA 19140United States

BACKGROUND Cardiovascular diseases are the major cause of mortality *** of the damaged myocardium remains a challenge due to mechanical constraints and limited healing ability of the adult heart *** tissue engineering using biomaterial scaffolds combined with stem cells and bioactive molecules could be a highly promising approach for cardiac *** of biomaterials can provide suitable microenvironment to the cells and can solve cell engraftment problems associated with cell transplantation *** stem cells(MSCs)are potential candidates in cardiac tissue engineering because of their multilineage differentiation potential and ease of *** of DNA methyl transferase inhibitor,such as zebularine,in combination with three-dimensional(3D)scaffold can promote efficient MSC differentiation into cardiac lineage,as epigenetic modifications play a fundamental role in determining cell fate and lineage specific gene *** To investigate the role of collagen scaffold and zebularine in the differentiation of rat bone marrow(BM)-MSCs and their subsequent in vivo *** MSCs were isolated from rat BM and characterized morphologically,immunophenotypically and by multilineage differentiation *** were seeded in collagen scaffold and treated with 3μmol/L zebularine in three different *** analysis was done and cardiac differentiation was analyzed at the gene and protein *** and untreated MSC-seeded scaffolds were transplanted in the rat myocardial infarction(MI)model and cardiac function was assessed by *** tracking was performed by DiI dye labeling,while regeneration and neovascularization were evaluated by histological and immunohistochemical analysis,*** MSCs were successfully isolated and seeded in collagen *** analysis revealed that zebularine was not cytotoxic in any of the treatment *** differentiation analysis

关键词： Mesenchymal stem cells Myocardial infarction Cardiac tissue engineering Demethylating agent Collagen scaffold Zebularine

Spatio-temporal variation of land surface temperature and temperature lapse rate over mountainous Kashmir Himalaya

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Mountain Science 2018年第3期15卷 563-576页

作者： shakil Ahmad ROMSHOO Mohammd RAFIQ Irfan RASHID Department of Earth Sciences University of Kashmir

In this study, Land Surface Temperature(LST) and its lapse rate over the mountainous Kashmir Himalaya was estimated using MODIS data and correlated with the observed in-situ air temperature(Tair) data. Comparison between the MODIS LST and Tair showed a close agreement with the maximum error of the estimate ±1°C and the correlation coefficient >0.90. Analysis of the LST data from 2002-2012 showed an increasing trend at all the selected locations except at a site located in the southeastern part of Kashmir valley. Using the GTOPO30 DEM, MODIS LST data was used to estimate the actual temperature lapse rate(ATLR) along various transects across Kashmir Himalaya, which showed significant variations in space and time ranging from 0.3°C to 1.2°C per 100 m altitude change. This observation is at variance with the standard temperature lapse rate(STLR) of 0.65°C used universally in most of the hydrological and other land surface models. Snowmelt Runoff Model(SRM) was used to determine the efficacy of using the ATLR for simulating the stream flows in one of the glaciated and snow-covered watersheds in Kashmir. The use of ATLR in the SRM model improved the R2 between the observed and predicted streamflows from 0.92 to *** is hoped that the operational use of satellite-derived LST and ATLR shall improve the understanding and quantification of various processes related to climate, hydrology and ecosystem in the mountainous and data-scarce Himalaya where the use of temperature and ATLR are critical parameters for understanding various land surface and climate processes.

关键词：陆地表面温度克什米尔时间显示差错率空间 MODIS 表面模型 LST

Morphotectonic and Lithostratigraphic Analysis of Intermontane Karewa Basin of Kashmir Himalayas,India

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2013年第1期10卷 1-15页

作者： Reyaz Ahmad DAR Rakesh CHANDRA shakil Ahmad ROMSHOO Department of Earth Sciences The University of Kashmir

Morpho-tectonic study plays an important role in deciphering the effects of tectonic activity in the geomorphic evolution of the drainage *** watershed forms one of the major watersheds of the intermontane Karewa Basin of Kashmir *** Karewa sediments are characterized by glacio-fluvio-lacustrine deposits capped by the aeolian *** geomorphic,morphometric and lithostratigraphic studies of these cap deposits have been carried out to elucidate the effect of tectonics on the geomorphic evolution of Romushi *** mapping was carried out using GPS measurements,DEM at 30m resolution,Topographic Position Index(TPI) model,topographic maps,LANDSAT TM Imagery and field *** and morphotectonic analyses in GIS environment were used to calculate various geomorphic indices(Mountain Front Sinuosity Index,Bifurcation Ratio,Asymmetry Factor,River Profile,etc).These indices reveal that the tectonic uplift observed in the region due to Himalayan orogeny coupled with mass movement and aeolian deposition have dominated the landscape evolution of intermontane Karewa Basin of Kashmir throughout the Late Quaternary *** data from lithostratigraphic measurements were analyzed to understand the geomorphic evolution of intermontane Karewa *** data revealed that the basin has experienced differential uplift and erosion rates from time to time in the geological *** was corroborated by the results from the morphometric and morphotectonic analysis.

关键词：喜马拉雅山脉地貌演化山间盆地克什米尔地层分析卡尔数字高程模型岩石

Modelling Chorabari Lake outburst flood, Kedarnath, India

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2019年第1期16卷 64-76页

作者： Mohammd RAFIQ shakil Ahmad ROMSHOO Anoop Kumar MISHRA Faizan JALAL Centre for Remote Sensing and Geoinformatics Sathyabama Institute of Science and Technology Department of Earth Sciences University of Kashmir

In this study, the Glacier Lake Outburst Flood(GLOF) that occurred over Kedarnath in June 2013 was modeled using integrated observations from the field and Remote Sensing(RS). The lake breach parameters such as area, depth, breach, and height have been estimated from the field observations and Remote Sensing(RS) data. A number of modelling approaches, including Snow Melt Runoff Model(SRM), Modified Single Flow model(MSF), Watershed Management System(WMS), Simplified Dam Breach Model(SMPDBK) and BREACH were used to model the GLOF. Estimations from SRM produced a runoff of about 22.7 m3 during 16–17, June 2013 over Chorabari Lake. Bathymetry data reported that the lake got filled to its maximum capacity(3822.7 m3) due to excess discharge. Hydrograph obtained from the BREACH model revealed a peak discharge of about 1699 m3/s during an intense water flow episode that lasted for 10–15 minutes on 17 th June 2013. Excess discharge from heavy rainfall and snowmelt into the lake increased its hydrostatic pressure and the lake breached cataclysmically.

关键词： Glacier lake outburst flood GIS Modelling Snow Melt Runoff Kedarnath Glacier Lake

The Effect of Injection Angle on Mixing and Flame Holding in Supersonic Combustor

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2002年第1期11卷 80-91页

作者： shakil Ahmed Mohammad Ali A. K. M. Sadrul Islam Department of Mechanical Engineering Bangladesh University of Engineering and Technology (BUET) Dhaka Bangladesh

A numerical study on mixing of hydrogen injected into a supersonic air stream has been performed by solving two-dimensional full Navier-Stokes equations. An explicit Harten-Yee Non-MUSCL Modified-flux-type TVD scheme has been used to solve the system of equations, and a zero-equation algebraic turbulence model to calculate the eddy viscosity coefficient. The main objectives of this study are to increase the mixing efficiency and flame holding capability of a supersonic combustor. The performance of combustor has been investigated by varying the hydrogen injection angle made with the direction of air stream considering anti-clockwise direction as positive. The injector position from left boundary, backward-facing step height and the inlet width of air stream are kept constant. The results show that upstream of injector the mixing is dominated by recirculation and in downstream the mixing is dominated by mass concentration of hydrogen. Upstream recirculation is dominant for injecting angle 600 and 900 . Incorporating the various effects, perpendicular injection shows the maximum mixing efficiency and its large upstream recirculation region has a good flame holding capability.

关键词： scramjet engine TVD scheme backward-facing step supersonic mixing supersonic stream flame holding.

Seaweed farming for food and nutritional security,climate change mitigation and adaptation,and women empowerment:A review

在线全文

学校读者我要写书评

暂无评论

Aquaculture and Fisheries 2023年第5期8卷 463-480页

作者： Fahmida Sultana Md Abdul Wahab Md Nahiduzzaman Md Mohiuddin Mohammad Zafar Iqbal Abrar shakil Abdullah-Al Mamun Md Sadequr Rahman Khan LiLian Wong Md Asaduzzaman Department of Marine Bioresource Science Faculty of FisheriesChattogram Veterinary and Animal Sciences UniversityKhulshiChattogram4225Bangladesh ECOFISH-II Activity WorldFishBangladesh and South Asia OfficeBananiDhaka1213Bangladesh Department of Fisheries and Marine Science Noakhali Science and Technology UniversityNoakhali3814Bangladesh Institute of Marine Biotechnology Universiti Malaysia TerengganuKuala-TerengganuTerengganu21030Malaysia

Seaweed is a promising marine macroalgae of the millennium,providing various ecological,social,and economic *** present,seaweed production reached 35.8 million t from farming,accounting for 97%of global seaweed output,with a world market of US$11.8 *** are an excellent source of nutritious human food because of their low lipid content,high minerals,fibers,polyunsaturated fatty acids,polysaccharides,vitamins,and bioactive *** seaweed sub-products offer unique properties to develop various functional foods for the food processing *** the perspective of climate change mitigation,seaweed farms absorb carbon,serve as a CO_(2)sink and reduce agricultural emissions by providing raw materials for biofuel production and livestock *** farming system also helps in climate change adaptation by absorbing wave energy,safeguarding shorelines,raising the pH of the surrounding water,and oxygenating the waters to minimize the impacts of ocean acidification and hypoxia on a localized ***,it contributes substantially to the sustainable development of the economic condition of coastal women by providing livelihood opportunities and ensuring financial *** review paper highlights the significance of seaweed farming in global food and nutritional security,mitigation and adaptation to global climate change,and women empowerment within a single *** review paper also outlined the major issues and challenges of seaweed farming for obtaining maximum benefits in these *** main challenges of making seaweed as a staple diet to millions of people include producing suitable species of seaweeds,making seaweed products accessible,affordable,nutritionally balanced,and attractive to the *** food products must be developed from seaweeds that may be considered equivalent to the foods consumed by humans *** of effective marine spatial planning to avoid user conflicts is vital for expanding the seawee

关键词： Seaweed Functional food Nutritional security Blue carbon Climate change adaptation Women empowerment