Investigating Unipolar Switching in Niobium Oxide Resistive Switches: Correlating Quantized Conductance and Mechanism

Memory devices based on resistive switching (RS) have not been fully realised due to lack of understanding of the underlying switching mechanisms. Nature of ion transport responsible for switching and growth of conducting filament in transition metal oxide based RS devices is still in debate. Here, we investigated the mechanism in Niobium oxide based RS devices, which shows unipolar switching with high ON/OFF ratio, good endurance cycles and high retention times. We controlled the boundary conditions between low-conductance insulating and a high-conductance metallic state where conducting filament (CF) can form atomic point contact and exhibit quantized conductance behaviour. Based on the statistics generated from quantized steps data, we demonstrated that the CF is growing atom by atom with the applied voltage sweeps. We also observed stable quantized states, which can be utilized in multistate switching

Controlled inter-state switching between quantized conductance states in resistive devices for multilevel memory

A detailed understanding of quantization conductance (QC), their correlation with resistive switching phenomena and controlled manipulation of quantized states is crucial for realizing atomic-scale multilevel memory elements. Here, we demonstrate highly stable and reproducible quantized conductance states (QC-states) in Al/Niobium oxide/Pt resistive switching devices. Three levels of control over the QC-states, required for multilevel quantized state memories, like, switching ON to different quantized states, switching OFF from quantized states, and controlled inter-state switching among one QC states to another has been demonstrated by imposing limiting conditions of stop-voltage and current compliance. The well defined multiple QC-states along with a working principle for switching among various states show promise for implementation of multilevel memory devices

GIS based modeling using Analytic Hierarchy Process (AHP) for optimization of landfill site selection of Rohtak city, Haryana (India)

Landfills are the most common method for the disposal of municipal solid waste the world over, as well as in India due to their low technical and economic requirements. The selection of an appropriate site for the establishment of a landfill is a complex process because it must combine social, environmental and technical parameters. The scientific selection of landfill site is based on several diverse criteria (Land Use and Land Cover, ground water table depth, soil permeability, surface water, roads distance, slop etc) and regulations. The study presents the selection of a site for the establishment of a landfill based on several criteria using geographic information system (GIS) based site suitability modeling and analytical hierarchy process (AHP). Site suitability modeling was implemented using Boolean and Index overlay models. Each criterion and sub criteria was evaluated with the aid of AHP to assign a relative weightage in the index overlay model. Rules and criteria’s set by Central Pollution Control Board (CPCB) and Central Public Health and Environmental Engineering Organisation (CPHEEO) were implemented through Boolean model. The combination of the results of the two models generated a map with several suitable sites. Further selection was done on basis of the size requirement of the site, to handle Municipal solid waste (MSW) for next ten years. Two sites having the maximum suitability and also fulfilling the size requirement were shortlisted. Final selection from the two sites was done by a field survey of the sites. Finally the site B was selected on the basis of field survey which revealed it being better on account of certain factors discussed and social acceptability

Association analysis for yield and related traits in fenugreek (Trigonella foenum-graecum L.) under different environmental conditions

Sixteen diverse genotypes of fenugreek (Trigonella foenum-graecum L.) were grown in five (E1 to E5) environments which were created by different date of sowing during the rabi seasons at the Vegetable Farm of CCS HAU, Hisar. (29°15?N, 75°69?E) during 2012-13. Observations were recorded on ten randomly selected plants from each genotypes in each replications for characters viz. field emergence index, days to 50 % flowering, plant height, number of pods per plant, number of branches per plant, number of seeds per pod, pod length, seed yield (q/ha), test weight, seed germination, seed vigour index-I and II. The estimation of genotypic and phenotypic coefficients (GCV and PCV) variation in all the environments was consistently decreasing with the delaying in sowing date for all the character studied except plant height and test weight indicating that the environmental influence was comparatively more pronounced for these characters in expressing the phenotypic performance of different genotypes. Highest GCV and PCV was estimated as 50.36 % and 55.93 %, respectively for seed vigour index-I in E1. High value of heritability estimated for characters seed yield, seed vigour index-II, seed germination and branches per plant (above 70 %) in E1 revealed that these were less influenced by environment and low heritability estimated for days to 50 % flowering in E2, plant height in E2, seeds per pod in E3, field emergence index in E5 indicated high influence of environment. Based on environmental indices, the environment E2 was most favourable for all the characters studied except field emergence index

Genetic variation and heritability estimation in Jatropha curcas L. progenies for seed yield and vegetative traits

In this study, experiment was conducted on sandy loam soils poor in organic carbon and water holding capacity in southern Haryana, India to determine the best progenies of Jatropha curcas for bio-diesel production. Fifty progenies raised from seed sources collected from nine states of India were evaluated after five years of plantation for growth, seed and oil content traits. The progenies showed significant (P> 0.05) differences for all the traits studied. Maximum seed yield/plant (879.37 g), number of capsules/plant (522.67) and plant height (408.33 cm) was recorded in P-44. Maximum oil content observed in P-37 (36.08%) followed by P-5 (35.64%). The magnitude of phenotypic coefficient of variation (PCV) was higher than the corresponding genotypic coefficient of variation (GCV) for all the characters studied. Heritability was highest for oil content (95.49%) and 100-seed weight (87.75%) followed by seed yield (75.54%). Total capsules/plant exhibited highest genetic advance (92.69%) followed by number of branches per plant (64.32%). Hierarchical Euclidean cluster analysis of all 50 progenies using D2 statistics was done where the D2 analysis grouped the progenies into five clusters. The intra cluster distances ranged from 1.33 to 2.72. The maximum inter-cluster distance was observed between cluster II and V (6.43) followed by I and V indicating greater divergence among progenies belonging to these clusters and an attempt to cross the progenies in these clusters should bring out desirable gene combinations. These progenies showed considerable potential which can be tapped for planting and selecting the improved varieties

Pongamia pinnata L. (Karanja) based agri-silviculture system under rainfed conditions of south-west Haryana

The present study was conducted to assess the the performance of Karanja based agri-silviculture system in rainfed conditions of south west Haryana. The results showed that the yield (grain and fodder) of different crops was not affected significantly by the Karanja trees during initial four years of plantation. The mean grain yield of crops viz. cowpea (9.47q/ha), cluster bean (9.13q/ha), dhaincha (8.57 q/ha) and mung bean (9.50q/ha) was slightly less in agri-silvicultue system as compared to sole cropping. Similar trend was also observed for fodderyield. Karanja growth (height and diameter) was more in agri-silviculture as compared to sole plantation. Maximum height of 300.00 cm and diameter of 89.20 mm was recorded when Karanja was intercropped with cowpea, whereas it was 281.20 cm (height) and 80.90 mm (diameter) in sole plantation. Agri-silviculture system also improved the organic carbon and available N, P, K as compared to sole cropping. The lower net returns from agri-silviculture system of Karanja + cowpea (Rs. 7178/ha), Karanja +clusterbean (Rs. 7725/ha), Karanja +dhaincha (Rs. 7254/ha) and Karanja + mung bean (Rs. 7100/ha) were mainly due to the fact that during initial years Karanja plantation required some cost without any economic return. It is evident from the results that the cost of establishment of plantation can be meet out through intercropping during the gestation period of Karanja plantation

SWI/SNF regulates a transcriptional programme that induces senescence to prevent liver cancer

Oncogene-induced senescence (OIS) is a potent tumour suppressor mechanism. To identify senescence regulators relevant to cancer, we screened an shRNA library targeting genes deleted in hepatocellular carcinoma (HCC). Here, we describe how knockdown of the SWI/SNF component ARID1B prevents OIS and cooperates with RAS to induce liver tumours. ARID1B controls p16INK4a and p21CIP1a transcription but also regulates DNA damage, oxidative stress and p53 induction, suggesting that SWI/SNF uses additional mechanisms to regulate senescence. To systematically identify SWI/SNF targets regulating senescence, we carried out a focused shRNA screen. We discovered several new senescence regulators including ENTPD7, an enzyme that hydrolyses nucleotides. ENTPD7 affects oxidative stress, DNA damage and senescence. Importantly, expression of ENTPD7 or inhibition of nucleotide synthesis in ARID1B-depleted cells results in re-establishment of senescence. Our results identify novel mechanisms by which epigenetic regulators can affect tumor progression and suggest that pro-senescence therapies could be employed against SWI/SNF-mutated cancers

Models of T cell antigen receptor activation: the puzzle still remained

T cell antigen receptor (TCR) is a protein-complex expressed on all T cells of the immune system and is responsible for the activation of T cells when infectious agent is presented by an antigen presenting cell (APC) in the form of peptides bound to the major histocompatibility complex (pMHC). Despite numerous studies it is not clear what biochemical changes upon binding of antigen ligand to the extracellular domains of TCR leads to activation of intracellular signaling (a process known as TCR triggering). This review summarizes possible biochemical mechanisms for TCR triggering and discusses their comparative limitations and advantages in explaining various experimental observations.Keywords: T cell antigen receptor; activation; modelDOI: http://dx.doi.org/10.3126/njb.v2i1.5684Nepal Journal of Biotechnology Jan.2012, Vol.2(1): 62-7

Evaluation of nasal mucociliary clearance in rheumatoid arthritis: a comparative analysis using saccharin test

Background: Rheumatoid arthritis (RA) is a chronic multisystem disease of unknown etiology characterized by persistent inflammatory synovitis, usually involving peripheral joints in a symmetric distribution. RA is a systemic disease often associated with cutaneous and organ-specific extra-articular manifestations the mucociliary clearance system protects the lower respiratory system by trapping and removing inhaled pathogenic viruses and bacteria, in addition to nontoxic and toxic particulates (e.g., pollen, ash, mineral dust, mold spores, and organic particles), from the lungs. Effective clearance requires both ciliary activity and the appropriate balance of periciliary fluid and mucus.Methods: This was a case control study conducted in the Department of Physiology, Pt. B.D. Sharma PGIMS, Rohtak in 50 females of age group 30-50 years. Control group comprised of 25 healthy volunteer females while study group comprised of 25 rheumatoid arthritis female patients with disease duration of more than five years. Proven cases of RA (as per 1987 ACR criteria) were taken with disease duration of more than five years from Rheumatology clinic of Pt. B.D. Sharma PGIMS, Rohtak. Nasal mucociliary clearance time was evaluated by saccharin method.Results: The results of our study showed abnormal mucociliary clearance in rheumatoid arthritis patients.Conclusions: The study shows an abnormal mucociliary clearance in rheumatoid arthritis patients. Impairment of mucociliary clearance seems to be the result of qualitative and quantitative alterations in respiratory secretions