Synthesis of nm-sized barium titanate crystallites using a new LTDS method and their characterization

A new LTDS method was established to synthesize nm-sized barium titanate crystallites with particle sizes around 10 nm. This LTDS method was the following two features, i.e., (1) a heat of neutralization in a neutralization reaction between strong acid and base can be used as a driving force for a formation of barium titanate, and (2) barium titanate crystallites can be directly synthesized from Ti and Ba ions, not via intermediates. Therefore, using the LTDS method, it can be expected that there is no minimum limit in particle sizes, and also no contamination in barium titanate crystallites. At first, optimum conditions for a formation of barium titanate were screened at various reaction temperatures and Ba/Ti atomic ratios in the starting materials. As a result, the formation of barium titanate was found at higher reaction temperatures than 50°C and higher Ba/Ti atomic ratios than 5. Under a constant temperature, particle sizes decreased with increasing Ba/Ti atomic ratios while under a constant Ba/Ti atomic ratio, particle sizes were independent of reaction temperatures. Finally, barium titanate crystallites with particle sizes below 10 nm were first prepared. These particles were also characterized using various methods.     

Field Investigations for Sustainable Groundwater Utilization in the Konan Basin

The Konan groundwater basin of Kochi Prefecture, Japan, is experiencing freshwater shortages for the past few years, particularly during the winter season. The present study aimed at analyzing the problem and exploring increased groundwater withdrawals to meet burgeoning freshwater demands in various sectors. The trend analysis of waterconsumption indicates that the groundwater demandwould increase by 43 and 52% by the years 2010 and2025, respectively, compared to 32 100 m³ d^-1 at present.The streamflow of the Monobe River reduces to a minimumin winter and it shows a decreasing trend in recentyears. The geologic investigation results indicatethat unconfined (phreatic) aquifers comprisingalluvial sand and gravel and/or diluvial silty sandand gravel are dominant, and that the northwestern andwestern portions of the basin have greater potentialfor groundwater. Groundwater flows essentially fromnorth to south into the ocean. Groundwater levelfluctuations over the basin vary appreciably in spaceand time, indicating a wide variation of naturalrecharge. Field observations confirm the hypothesisthat stream-aquifer interaction also significantlycontributes to groundwater recharge, besides therainfall infiltration. Further, the pumping testsresults demonstrate that though the aquifers arelow-yielding, enhanced groundwater withdrawals couldbe possible. The aquifer hydraulic conductivity ischaracterized as high and ranges from 65 to 804 m d^-1(mean = 229 m d^-1), thereby suggesting great aquiferheterogeneity. Finally, it is concluded that thelong-term sustainability of the scarce groundwaterresource of the Konan basin is doubtful, and that acomprehensive analysis of the groundwater system isessential prior to formulating plans for the futuregroundwater development and management.     

Effect of ammonia via prepyriform cortex on regulation of food intake in the rat

Studies were made on whether ammonia, which is an obligatory intermediate of amino acid metabolism, depresses the food intake of rats fed a low-casein (basal) diet containing imbalanced amino acid mixtures (imbalanced diets). Bilateral lesions in the prepyriform cortex caused normalization of food intake of rats fed amino acid-imbalanced diets, confirming the work of Leung and Rogers (Am. J. Physiol. 221:929-935, 1971). Unlike normal rats, animals with prepyriform cortical lesions consumed as much of a diet containing 3% NH4Cl as they did of the basal diet. However, like normal rats, they rejected a diet containing a mixture of keto acids. Unilateral injection of NH4Cl into prepyriform cortical areas reduced the food intake to a greater extent than injection of NaCl into these areas or injection of NH4Cl into other parts of the brain. These results suggest that ammonium ions influence the appetite through their effect on prepyriform cortical areas.     

Phosphohydrolytic activity in Paramecium caudatum at neutral pH

Phosphohydrolytic activity was cytochemically characterized in Paramecium caudatum, a ciliated protozoa, at neutral pH. We stained cells in the presence of several mononucleotides as substrates, namely adenosine 5'-monophosphate (5'-AMP), adenosine 2'-monophosphate, guanosine 5'-monophosphate (5'-GMP) and beta-glycerophosphate (beta-GLP) using a lead capture method at 37 degrees C. Cells were also incubated in the presence of 5'-AMP with the inhibitor for alkaline phosphatase, tetramisole. In all cases, varying amounts of final reaction product, lead sulfide, was observed in Paramecium cytoplasm. Tetramisole did not have any effect on Paramecium 5'-AMP hydrolytic activity. The phosphohydrolytic activity was measured as the increase in total absorbance of "test minus control" reactions at 440 nm per unit time after 20 min of incubation using a microphotometric system for image analysis that has been developed by us. From the relationship between the concentrations of 5'-AMP and activity, an apparent K(m) value was estimated to be 0.20 mM. These results suggest that mononucleotides and phosphate monoesters are hydrolyzed by one or more enzymes with wide substrate specificity in P. caudatum. All the activity distribution patterns in Paramecium cultures, that were tested, were monomodal. The mean activity for 5'-AMP hydrolysis widely varied in these cultures. To investigate substrate affinity, distribution patterns and mean activity with 5'-AMP as substrate were compared with those in the presence of 2 other substrates, 5'-GMP and beta-GLP. Affinity of the enzyme(s) was similar for 5'-AMP and 5'-GMP and lower for beta-GLP.     

Sodium-doped carbon nitride nanotubes for efficient visible light-driven hydrogen production

Nano Research - Sodium-doped carbon nitride nanotubes (Na x -CNNTs) were prepared by a green and simple two-step method and applied in photocatalytic water splitting for the first time....     

Cost-effective Approaches for Sustainable Groundwater Management in Alluvial Aquifer Systems

The consequences of unsustainable use of groundwater are becoming increasingly evident worldwide, particularly in developing nations. Groundwater management is a serious problem in many parts of the world. The prime concern is how to achieve groundwater sustainability. Artificial recharge techniques coupled with water harvesting hold a great promise for groundwater sustainability. The main intent of this paper is to highlight salient cost-effective and easy-to-use methods for augmenting groundwater resources in the alluvial hydrogeologic setting. Based on the intensive field investigation in a groundwater basin of Japan, three low-cost and easy-to-implement recharge techniques are suggested for alluvial aquifer systems, viz., augmentation of river flow, recharge through irrigation/drainage canals, and recharge from paddy fields. The source of recharge water for these recharge techniques is surface water supply. The efficacy of these methods or approaches has been demonstrated. It is emphasized that such cost-effective methods of groundwater recharge are key to sustainable groundwater management in both developing and developed countries. These methods must not be overlooked in the midst of sophisticated and highly expensive methods.