Photovoltage Bleaching in Bulk Heterojunction Solar Cells through Occupation of the Charge Transfer State

We observe a strong peak in the capacitive photocurrent of a MDMO-PPV / PCBM bulk heterojunction solar cell for excitation below the absorbance threshold energy. Illumination at the peak energy blocks charge capture at other wavelengths, and causes the photovoltage to drop dramatically. These results suggest that the new peak is due to a charge transfer state, which provides a pathway for charge separation and photocurrent generation in the solar cell.Comment: submitted to Physical Review Letter

Organic and composite aerogels through ring opening metathesis polymerization (ROMP)

Aerogels are open-cell nanoporous materials, unique in terms of low density, low thermal conductivity, low dielectric constants and high acoustic attenuation. Those exceptional properties stem from their complex hierarchical solid framework (agglomerates of porous, fractal secondary nanoparticles), but they also come at a cost: low mechanical strength. This issue has been resolved by crosslinking silica aerogels with organic polymers. The crosslinking polymer has been assumed to form a conformal coating on the surface of the skeletal framework by covalent bridging elementary building blocks. However, assuming is not enough: for correlating nanostructure with bulk material properties, it is important to know the exact location of the polymer on the aerogel backbone. For that investigation, we synthesized a new norbornene derivative of triethoxysilane (Si-NAD) that can be attached to skeletal silica nanoparticles. Those norbornene-modified silica aerogels were crosslinked with polynorbornene by ring opening metathesis polymerization (ROMP). The detailed correlation between nanostructure and mechanical strength was probed with a wide array of characterization methods ranging from molecular to bulk through nano. Subsequently, it was reasoned that since the polymer dominates the exceptional mechanical properties of polymer crosslinked aerogels, purely organic aerogels with the same nanostructure and interparticle connectivity should behave similarly. That was explored and confirmed by: (a) synthesis of a difunctional nadimide monomer (bis-NAD), and preparation of robust polyimide aerogels by ROMP of its norbornene end-caps; and, (b) synthesis of dimensionally stable ROMP-derived polydicyclopentadiene aerogels by grafting the nanostructure with polymethylmethacrylate (PMMA) via free radical chemistry --Abstract, page iv

Data-Driven Population Inference from Gravitational-Wave Sources and Electromagnetic Counterparts

Gravitational-wave (GW) astronomy has presented an unprecedented way to view the universe and study populations of astrophysical objects such as merging compact binaries containing black holes (BHs) and neutron stars (NSs). With the latest catalog of observations detected by the Advanced LIGO-Virgo detector network, recent analyses are placing interesting constraints on the population of BHs and NSs in these binaries. In particular, we are learning a great deal about how these binaries are distributed as a function of their masses. Another aspect of GW astronomy that has the potential to provide insights into fundamental physics is the multi-messenger follow up of the potential kilonova from binary mergers involving NSs. Observations or non-detections of kilonovae can be used to learn more about the formation of heavy elements via r-process nucleosynthesis as well as to shed light on the inner mechanisms of such mergers. This dissertation presents two studies that focus on inferring population properties from compact binaries using data-driven methods. The first is using the flexible approach of Gaussian processes to model the mass distribution of compact binaries and the second is developing a hierarchical Bayesian inference framework to infer kilonova population properties using non-detections in electromagnetic surveys

Effect of Selective Up regulation of Prostacyclin Synthesis On Its Signaling And Vascular Protection

Prostacyclin (PGI2) is a very important endogenous vascular protector. It provides vascular protection through actions like vasodilatation, platelet aggregation and vascular smooth muscle cell proliferation inhibition and smooth muscle differentiation regulation. Therefore since decades, there have been many ongoing attempts to use PGI2 to treat vascular disorders such as pulmonary arterial hypertension, peripheral artery disease and thrombosis. However, the short half-life of PGI2 has limited its therapeutic potential. PGI2 is synthesized endogenously from arachidonic acid using enzymes cyclooxygenase isoform 1/2(COX-1/2) and prostacyclin synthase (PGIS). Single gene therapy with either COX or PGIS through adenoviral vectors does not specifically overproduce PGI2 and also is associated with inflammatory reactions. Thus to address these problems, our lab engineered a single hybrid gene (COX-1-10aa-PGIS) by fusing COX-1 with PGIS through transmembrane linker of 10 amino acids (10aa). Adipose tissue derived cells have been used therapeutically in several vascular disorders due to their regenerative properties. Thus we isolated and cultured mature adipocytes (MA) from mouse adipose tissue and called it as prostanoid synthesizing fat cells (PSFC). Further, we engineered a novel adipose tissue-derived cell that constantly produces PGI2, through transfecting of the engineered cDNA of the hybrid enzyme (human COX-1-10-aa-PGIS), which has superior triple catalytic functions in directly converting arachidonic acid into PGI2. The gene-transfected cells were further converted into a stable cell line, in which the cells constantly expressed the hybrid enzyme and were capable of overproducing specifically PGI2 and thus we called this cell line as PGI2 producing PSFC (PGI2-PSFC). When the results of the HPLC activity assay and LC/MS/MS were compared between just vector transfected (PSFC) and COX-1-10aa-PGIS gene transfected cells (PGI2-PSFC), it was observed that the majority of the endogenous AA metabolism shifted from that of unwanted PGE2 (in PSFC) to that of the preferred PGI2 (in PGI2-PSFC) with a PGI2/PGE2 ratio change from 0.03 to 25. The PGI2-producing cell line not only exhibited an approximate 50-fold increase in PGI2 biosynthesis, but also demonstrated superior anti-platelet aggregation in vitro, and increased reperfusion in the mouse ischemic hindlimb and thrombogenesis models in vivo. PGI2 regulates functions like vascular smooth muscle cell differentiation and proliferation and apoptosis. These actions are mediated through the PGI2 receptor (IP) and nuclear receptor, peroxisome proliferator-activated receptors (PPAR). MicroRNAs (miRNAs), which are negative regulators of gene expression, also regulate similar functions like PGI2. PGI2 regulates expression of genes by signaling through PPARs. Thus to find out if PGI2 regulates gene expression by regulating miRNA expression by signaling through the IP and PPAR, a miRNA microarray analysis of the PGI2-PSFCs and PSFCs was performed. Analysis of the results obtained from miRNA study, revealed that PGI2 is involved in regulating cellular microRNA (miRNA) expression through its receptors in the mouse adipose tissue-derived primary culture cell line overexpressing COX-1-10aa-PGIS (PGI2-PSFC). The miRNA microarray analysis of the PGI2-PSFC revealed a significant up-regulation (711, 148b, and 744) and down-regulation of miRNAs of interest, which were reversed by antagonists to the IP and PPARγ receptors. Furthermore, we also found that the insulin-mediated lipid deposition was inhibited in the PGI2-PSFCs. The study also initiated a discussion, which suggested that the endogenous PGI2 inhibition of lipid deposition in adipocytes could involve miRNA-mediated inhibition of expression of the targeted genes specifically of Akt1. To translate the results of in vitro study, a transgenic mouse permanently expressing the COX-1-10aa-PGIS gene was generated. This genetic mouse animal model was used to study the effect of COX-1-10aa-PGIS overexpression on PGI2 production in vivo and as well as its vascular protective effect. The transgenic mice was genotyped using polymerase chain reaction and further bred to develop a colony of homozygous transgenic mice. Quantitative PCR was performed to distinguish between the hemizygous and homozygous mice. PCR and imunoblot analysis of all the organs and tissues of mice revealed the expression of COX-1-10aa-PGIS in adipose tissue, brain, heart and uterus. LC/MS analysis of urine and plasma revealed approximately five-folds increase in PGI2 biosynthesis permanently in vivo. The animals showed strong resistance to photochemical induced thrombosis. They produced healthy pups with a an increase in live births when compared to the wild type without significant adverse effects in development and functions of major organs including brain, heart, kidneys. Tail cuff method was used to measure blood pressure of the mice which was similar to that in the wild type. Thus PGI2-PSFCs (therapeutic cells) can be used as cell therapy as an alternative to adenoviral gene transfer to treat ischemic and vascular conditions. The cells, which have an ability to increase the biosynthesis of the vascular protector, PGI2, while reducing that of the vascular inflammatory mediator, PGE2, provide a dual effect on vascular protection, which is not available through any existing drug treatments. Thus, the current finding has potential to be an experimental intervention for PGI2-deficient diseases, such as pulmonary arterial hypertension. PGI2 mediated gene expression regulation through miRNA expression regulation has unraveled a novel signaling mechanism for PGI2. This signaling could exist in broad pathophysiological processes involving PGI2 (i.e. apoptosis, vascular inflammation, cancer, embryo implantation, and obesity). The results of the transgenic mice overexpressing COX-1-10aa-PGIS and producing PGI2 provides the first evidences that risk of stroke and heart diseases could be reduced by the human transgene, as well as the insight into the possible future transgenic medicine to prevent and reduce the genetic risk of heart disease.Pharmacological and Pharmaceutical Sciences, Department o

A Study on SIDBI’s various Scheme for MSMEs Development

Micro, Small and Medium industries are engine of economic growth of India. They are spread all over India SIDBI is played important role in the development of Micro, Small and Medium industries. SIDBI has consciously adopted a ‘Credit Plus’ approach under which the SIDBI notice the Promotional and Developmental needs to MSMEs as well as other financial institutions along with their financial needs.            SIDBI is actively granting support in the areas of cluster development, rural industrialization, technological up-gradation, entrepreneurship development, advisory services, promoting innovation and market linkages, etc. On the basis of promotional and development (P&D) involvement have made noticeable socio-economic impact benefitting more than 2.3 lakh persons in the MSME sector.  As well, more than 1.5 lakh employments have been created and over 80,000 unit’s mostly rural enterprises have been set up.            SIDBI plays an important role in the development of Micro, Small and Medium industries, the paper highlight on different schemes of SIDBI in the growth of MSMEs and review its impact on said sector

Mesoscale modeling of the rheology of pressure sensitive adhesives through inclusion of transient forces

For optimal application, pressure-sensitive adhesives must have rheological properties in between those of a viscoplastic solid and those of a viscoelastic liquid. Such adhesives can be produced by emulsion polymerisation, resulting in latex particles which are dispersed in water and contain long-chain acrylic polymers. When the emulsion is dried, the latex particles coalesce and an adhesive film is formed. The rheological properties of the dried samples are believed to be dominated by the interface regions between the original latex particles, but the relation between rheology and latex particle properties is poorly understood. In this paper we show that it is possible to describe the bulk rheology of a pressure-sensitive adhesive by means of a mesoscale simulation model. To reach experimental time and length scales, each latex particle is represented by just one simulated particle. The model is subjected to oscillatory shear flow and extensional flow. Simple order of magnitude estimates of the model parameters already lead to semi-quantitative agreement with experimental results. We show that inclusion of transient forces in the model, i.e. forces with memory of previous configurations, is essential to correctly predict the linear and nonlinear properties.Comment: 29 pages, 8 figure

Mortality estimates of Indian ribbon fish Trichiurus lepturus off Maharashtra coast

In view of its new found status in export market, ribbon fish resources need to be continually monitored. Mortality, one of the important parameter is reported for the Indian ribbon fish Trichiurus lepturus Linnaeus in the present communication. The average annual instantaneous rate of total (Z), natural (M) and fishing mortality coefficient (F) were estimated as 2.66, 0.77 and 1.89 respectively for the 1995 to 1997 period. The exploitation rate (U) and exploitation ratio (E) were estimated as 0.66 and 0.71 respectively, which is beyond the optimum thrust reduction in the fishing effort for this stock along the Maharashtra coast is necessary