Quantitative impact assessment of temperature on the economics of a rooftop solar photovoltaic system.

This paper analyzes the economics of a grid-interactive rooftop solar photovoltaic (PV) system and the impact of the temperature on it. The analysis related to energy metrics, lifecycle costing, and environmental economics was performed considering the PV system's life as 30 years. The system economics is also compared at different conditions like theoretical, temperature-corrected, and real electricity generation data. The parameters like energy payback time (EPBT), energy return on energy invested (EROI), and lifecycle conversion efficiency are determined as 5.95 years, 5.04, and 0.078, respectively, based on actual generation. The unit electricity cost of the rooftop PV system was estimated as INR 5.37 at the 5% interest rate. The electricity cost varies with the interest rate variation and operation system life. The results show a reduction in overall economic performance on the increase in module temperature. The effect of temperature on the economics of the system is presented in terms of the per degree rise of module temperature. One degree increase of module temperature 8.5 days in EPBT of the PV system increases, and INR 0.021 increases in the unit cost of electricity considering a reference temperature 25 °C. A PV system has environmental benefits by reducing greenhouse gas emissions, which are also affected by the rise of module temperature. The system lost INR 355.93 in carbon credits at an increase of one-degree module temperature.

A SEM evaluation of dentinal adaptation of root canal obturation with GuttaFlow and conventional obturating material.

OBJECTIVE: The aim of this in-vitro study was to compare dentinal adaptation of conventional obturating material and GuttaFlow in young permanent teeth of child patients. MATERIALS AND METHODS: Ten young permanent anterior teeth with closed foramen were selected for the study. Root canal preparations were carried out using a step back technique. The canal was alternately irrigated with 5.25% sodium hypochlorite solution and 17% EDTA and normal saline. After root canal preparation specimens were randomly divided into two groups (n=5). GROUP "A": Obturated with zinc-oxide eugenol sealer and gutta-percha cone using cold lateral obturation technique. GROUP "B": Obturated with GuttaFlow as per the manufacturer's instruction. The teeth were split into two halves. Five randomly chosen longitudinal split teeth samples each from Group "A" and Group "B" was observed under scanning electron microscope to access the interface between obturating material and dentin at the level of 2 mm from the apex. RESULTS: On statistical analysis the dentinal adaptation (µm) of Group A was observed with a mean of 0.52 and standard deviation 0.15, while the value of mean and standard deviation were noted 0.12 and 0.02 for Group B. The "t" value on comparison of Group A and Group B is 5.79 with "P " value of <0.001, which is highly significant. CONCLUSION: From result of the study it can be concluded Group B samples showed significantly superior seal when compared with Group A. Complete seal was not observed in any of Group A samples.

Proton HR-MAS NMR spectroscopic characterization of metabolites in various human organ tissues: pancreas, brain and liver from trauma cases.

High-Resolution Magic Angle Spinning (HR-MAS) NMR has been employed to characterize various metabolites of human pancreas, liver and brain tissues from trauma cases. The potential usefulness of NMR in identifying the metabolites in human tissues has been explored using a combination of one- and two-dimensional experiments. The complete resonance assignments of pancreas tissue have been carried out for the first time. Two new metabolites, alpha-hydroxyisovalarate and alpha-hydroxybutarate were identified in all the tissue specimens. The metabolites information of these human tissues can further be utilized in correlating several diseases associated with pathological manifestations as well in distinguishing traumatic tissues along with control tissues of pancreas, liver and brain.

Biogenic arsenopyrite in holocene peat sediment, India.

The plant organic matter in the peat layer deposited around 6650+/-110 and 4800+/-80 years BP, during the transgressive and regressive phases of sea level changes, respectively in the dried part (playa) of the present Pulicat lagoon in Palar Basin (southeast coast of India) was studied to elucidate the biogenic pyrite generation and associated trace elements. The scanning electron microscopic (SEM) observations show strongly curved unique C-shaped bacteria of uniform coccoidal shape and size (1 microm) freely scattered on the plant epidermal microfragments. These form spheroidal microcolonies 8-15 microm in diameter attached to the epidermis in a linear fashion or haphazardly enclosed in the translucent sheath as observed in surface view. These colonies are dense with a number of toxic trace elements as analyzed under an SEM-EDX spectrometer indicating its affinity toward metal binding. On maturity the sheath ruptures disseminating tetrad form of bacteria along with some C-shaped bacteria and few rhombohedral crystals of framboidal pyrite. The pyrite crystals intact in spheroidal shape in cavities on the epidermal fragments indicate its biogenic precipitation mediated by the bacteria. The pyrite crystals are rich in sulfur, iron, and traces of arsenic when analyzed by the SEM-EDX spectrometer. It is suggested that cubic and pyritohedran forms of crystals are perhaps arsenopyrite precipitated biogenically in saturated coastal wetland ecosystem in the past mediated by tetrad strain of the observed coccoid bacteria. Thus, the strata-bound peat layer could be the potent residing place for arsenopyrite or other toxic trace elements that may contaminate the groundwater aquifer.