Gasifier-based power generation: technology and economics

The paper describes a 100 kW power generation system installed at Port Blair, Andaman and Nicobar Islands, under a project sponsored by the Department of Non-Conventional Energy Sources, Government of India. The system consists of a wood gasifier utilising the waste wood from a saw mill and a diesel engine genset. The performance of the total system and its elements are presented along with economics of operation. To bring out the economics of using such renewable energy devices for power generation, some realistic situations are considered for which the effective cost of power and the pay-back period for the investment are evaluated. The economics is compared with that of a similar system of 3.7 kW capacity

Five-kilowatt wood gasifier technology: evolution and field experience

Various elements of an efficient and reliable 5k W wood gasifier system developed over the last ten years are described. The good performance obtained from the system is related to the careful design of its components and sub-systems. Results from extensive testing of gasifier prototypes at two national centres are discussed along with the experience gained in the field from their use at more than one hundred and fifty locations spread over five states in the country. Issues related to acceptance of the technology are also included. Improvements in design to extend the life, to reduce the cost, and to reduce the number of components are also discussed. A few variants of the design to meet the specific requirements of water pumping, power generation and to exploit specific site characteristics are presented

Differential Effects of Leptin on the Invasive Potential of Androgen-Dependent and -Independent Prostate Carcinoma Cells

Obesity has been linked with an increased risk of prostate cancer. The formation of toxic free oxygen radicals has been implicated in obesity mediated disease processes. Leptin is one of the major cytokines produced by adipocytes and controls body weight homeostasis through food intake and energy expenditure. The rationale of the study was to determine the impact of leptin on the metastatic potential of androgen-sensitive (LNCaP) cells as well as androgen-insensitive (PC-3 and DU-145) cells. At a concentration of 200 nm, LNCaP cells showed a significant increase (20% above control; P < .0001) in cellular proliferation without any effect on androgen-insensitive cells. Furthermore, exposure to leptin caused a significant (P < .01 to P < .0001) dose-dependent decrease in migration and invasion of PC3 and Du-145 prostate carcinoma cell lines. At the molecular level, exposure of androgen-independent prostate cancer cells to leptin stimulates the phosphorylation of MAPK at early time point as well as the transcription factor STAT3, suggesting the activation of the intracellular signaling cascade upon leptin binding to its cognate receptor. Taken together, these results suggest that leptin mediates the invasive potential of prostate carcinoma cells, and that this effect is dependent on their androgen sensitivity

Insulin Resistance Impairs Circulating Angiogenic Progenitor Cell Function and Delays Endothelial Regeneration

OBJECTIVE Circulating angiogenic progenitor cells (APCs) participate in endothelial repair after arterial injury. Type 2 diabetes is associated with fewer circulating APCs, APC dysfunction, and impaired endothelial repair. We set out to determine whether insulin resistance adversely affects APCs and endothelial regeneration. RESEARCH DESIGN AND METHODS We quantified APCs and assessed APC mobilization and function in mice hemizygous for knockout of the insulin receptor (IRKO) and wild-type (WT) littermate controls. Endothelial regeneration after femoral artery wire injury was also quantified after APC transfusion. RESULTS IRKO mice, although glucose tolerant, had fewer circulating Sca-1+/Flk-1+ APCs than WT mice. Culture of mononuclear cells demonstrated that IRKO mice had fewer APCs in peripheral blood, but not in bone marrow or spleen, suggestive of a mobilization defect. Defective vascular endothelial growth factor–stimulated APC mobilization was confirmed in IRKO mice, consistent with reduced endothelial nitric oxide synthase (eNOS) expression in bone marrow and impaired vascular eNOS activity. Paracrine angiogenic activity of APCs from IRKO mice was impaired compared with those from WT animals. Endothelial regeneration of the femoral artery after denuding wire injury was delayed in IRKO mice compared with WT. Transfusion of mononuclear cells from WT mice normalized the impaired endothelial regeneration in IRKO mice. Transfusion of c-kit+ bone marrow cells from WT mice also restored endothelial regeneration in IRKO mice. However, transfusion of c-kit+ cells from IRKO mice was less effective at improving endothelial repair. CONCLUSIONS Insulin resistance impairs APC function and delays endothelial regeneration after arterial injury. These findings support the hypothesis that insulin resistance per se is sufficient to jeopardize endogenous vascular repair. Defective endothelial repair may be normalized by transfusion of APCs from insulin-sensitive animals but not from insulin-resistant animals

Oxidative stress in hepatitis C infected end-stage renal disease subjects

BACKGROUND: Both uremia and hepatitis C infection is associated with increased oxidative stress. In the present study, we aimed to find out whether hepatitis C infection has any impact on oxidative stress in hemodialysis subjects. METHODS: Sixteen hepatitis C (+) hemodialysis subjects, 24 hepatitis C negative hemodialysis subjects and 24 healthy subjects were included. Total antioxidant capacity, total peroxide level and oxidative stress index were determined in all subjects. RESULTS: Total antioxidant capacity was significantly higher in controls than hemodialysis subjects with or without hepatitis C infection (all p < 0.05/3), while total peroxide level and oxidative stress index were significantly lower (all p < 0.05/3). Hepatitis C (-) hemodialysis subjects had higher total antioxidant capacity compared to hepatitis C (+) hemodialysis subjects (all p < 0.05/3). Total peroxide level and oxidative stress index was comparable between hemodialysis subjects with or without hepatitis C infection (p > 0.05/3). CONCLUSION: Oxidative stress is increased in both hepatitis C (+) and hepatitis C (-) hemodialysis subjects. However, hepatitis C infection seems to not cause any additional increase in oxidative stress in hemodialysis subjects and it may be partly due to protective effect of dialysis treatment on hepatitis C infection

Prikaz stanja silicijevih MOS upravljanih učinskih sklopova i PiN ispravljača

Revolutionary advances and developments have been made in power semiconductor device technologies during the last decades which have allowed the improvement of power electronic systems in terms of their efficiency and reliability. The advent of MOS-gated power switches such as the power MOSFET and the IGBT showing high input impedance has been a real breakthrough in the design and fabrication of power electronic systems. This paper reviews the recent progress in the development of Si MOS-gated power devices and rectifiers. The evolution of these devices’ technologies together with the introduction of revolutionary device concepts is also discussed. Concretely, the introduction of trench technologies for power MOSFETs and the use of the super-junction concept for breaking the 1D-silicon limit are highlighted. Developments in IGBTs such as those based on the use of thin wafers and strategies for optimising the plasma distribution in PT IGBTs during the on-state are also addressed. Finally, advances in PiN diode technologies including new concepts for both the anode and the cathode structures are also reviewed. These approaches have allowed the reduction of the PiN total losses and a soft reverse recovery behaviour, leading to a more rugged device.U posljednjim desetljećima svjedočimo razvoju sustava učinske elektronike u pogledu povećanja efikasnosti i pouzdanosti. Napredak je omogućen zahvaljujući izvanrednom napredku koji je postignut na području učinskih poluvodiča. Pojava MOS upravljanih učinskih sklopova s visokom ulaznom impedancijom, kao što su MOSFET i IGBT, rezultirao je probojem u projektiranju i proizvodnji sustava učinske elekronike. Ovaj članak daje uvid u napredak koji je u posljednje vrijeme ostvaren u razvoju silicijeve MOS upravljane učinske elektronike i ispravljača. Uz dosadašnji razvoj tehnologije navedenih komponenata, u članku je uključen i osvrt na revolucionarne koncepte budućeg razvoja. Konkretno, u radu su objašnjene tehnologija rova za MOSFET i korištenje koncepta super spoja za probijanje granice jednodimenzionalnog silicija. Razmatrana su i poboljšanja IGBT-ova koja se baziraju na uporabi tankih pločica a strategijama optimiranja distribucije plazme u PT IGBT-ovima za vrijeme aktivnog stanja. Konačno, prikazan je i napredak u tehnologiji PiN dioda koji uključuje nove strukturalne koncepte katode i anode. Ovi pristupi su omogućili smanjenje ukupnih gubitaka PiN diode i blagu dinamiku reverznog oporavka, što rezultira povećanjem robusnosti sklopa

Guiding the Design of Synthetic DNA-Binding Molecules with Massively Parallel Sequencing

Genomic applications of DNA-binding molecules require an unbiased knowledge of their high affinity sites. We report the high-throughput analysis of pyrrole-imidazole polyamide DNA-binding specificity in a 10^(12)-member DNA sequence library using affinity purification coupled with massively parallel sequencing. We find that even within this broad context, the canonical pairing rules are remarkably predictive of polyamide DNA-binding specificity. However, this approach also allows identification of unanticipated high affinity DNA-binding sites in the reverse orientation for polyamides containing β/Im pairs. These insights allow the redesign of hairpin polyamides with different turn units capable of distinguishing 5′-WCGCGW-3′ from 5′-WGCGCW-3′. Overall, this study displays the power of high-throughput methods to aid the optimal targeting of sequence-specific minor groove binding molecules, an essential underpinning for biological and nanotechnological applications