The Structure of Information Networks

We develop a model of information acquisition in a network where agents pay for all the information they acquire including those through indirect links. The cost of information depends on the value of information itself and the distance it traverses in the network. We find that when the costs of information increase with distance, the complete network is the only Nash network. When costs of information decrease with distance capturing delay, all equilibrium information networks are minimally connected, though not all trees are Nash. We analyze the popular star and chain networks and identify strict Nash networks. We show that there is almost no divergence between efficient and equilibrium information networks. We explore the implications of a spatial model and information decay and discuss the relationship with experimental evidence.Nash networks, information networks, efficient networks

Influence of Citrate and Phosphate on the Adsorption of Adenosine-5′-Monophosphate at the Hematite Water Interface

Nucleic acid derived organic phosphorus (Po) is an important source of plant available P when degraded to inorganic phosphate (P(V)i). It is known that when nucleic acids or components are adsorbed on mineral surfaces, the enzymatic degradation is hindered or delayed. Thus, understanding adsorption/desorption mechanisms of nucleic acids and their derivatives are key to assess the biogeochemical pathways of Po cycling. Here we report adsorption mechanisms of adenosine-5′-monophosphate (AMP) on hematite, a common iron oxide mineral, under various solution properties using macroscopic and in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopic probes. The effects of citrate, mimicking organic acids from roots exudates, and the influence of P(V)i, representing inorganic fertilizer application, were also evaluated on the release of adsorbed AMP under various solution properties. The results suggested that AMP adsorbed with the hematite surface via the phosphate moiety, N7 atom and the π electron systems of the adenine moiety. The presence of citrate significantly decreased the AMP adsorption, which was also corroborated by the negative phosphate IR bands in the results of AMP and citrate competitive adsorption experiments monitored by in situ ATR-FTIR probe. Like citrate, P(V)i also reduced AMP adsorption on hematite. Our findings suggest a potential novel pathway of nucleic acid derived Po cycling in the soil environment

Development and Characterization of Ag-Cu-Ti Alloys for Ceramic Brazing

In the present investigation, silver and copper base alloys with varying compositions of Ag:Cu = 72:28, 60:40, 50:50 and 30:70 (by wt%) are prepared. In each set, 1, 2 and 3w1% of active filler element, i.e. titanium is incorporated by powder metallurgical route. The samples are characterised by XRD, DTA-TGA, SEM and EDX. The XRD results show that titanium and its related phases are not present due to the lower concentration of Ti in these samples. Energy dispersive X-ray analyses reveal that most of the titanium is present in the copper rich phase and very little in the silver rich phase. The rolled brazing alloys are used for./pining the alumina to alumina, that showed excellent joining characteristics

Antimony (V) Adsorption at the Hematite–Water Interface: A Macroscopic and In Situ ATR-FTIR Study

The environmental mobility of antimony (Sb) is largely unexplored in geochemical environments. Iron oxide minerals are considered major sinks for Sb. Among the different oxidation states of Sb, (+) V is found more commonly in a wide redox range. Despite many adsorption studies of Sb (V) with various iron oxide minerals, detailed research on the adsorption mechanism of Sb (V) on hematite using macroscopic, spectroscopic, and surface complexation modeling is rare. Thus, the main objective of our study is to evaluate the surface complexation mechanism of Sb (V) on hematite under a range of solution properties using macroscopic, in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopic, and surface complexation modeling. The results indicate that the Sb (V) adsorption on hematite was highest at pH 4–6. After pH 6, the adsorption decreased sharply and became negligible above pH 9. The effect of ionic strength was negligible from pH 4 to 6. The spectroscopic results confirmed the presence of inner- and outer-sphere surface complexes at lower pH values, and only outer-sphere-type surface complex at pH 8. Surface complexation models successfully predicted the Sb (V) adsorption envelope. Our research will improve the understanding of Sb (V) mobility in iron-oxide-rich environments

GC-MS ANALYSIS AND EVALUATION OF BIOACTIVITIES OF KAEMPFERIA PARISHII - A NATURAL SOURCE OF TOTAROL

Objective: The present study was aimed for phytoconstituent analysis, in vitro antioxidant and antimicrobial activities of leaf and rhizome extracts of an unexplored plant, Kaempferia parishii (Zingiberaceae).Methods: The extracts were analyzed by gas chromatography/mass spectrometry to determine volatile chemical constituents. Antioxidant activity of extracts was determined using DPPH assay whereas the antimicrobial effects were tested by inhibition zone diameter and minimum inhibitory concentration.Results: GC/MS analysis revealed the presence of 7 and 8 identified components accounting for 92.1% and 82.86% of the leaf and rhizome extract of Kaempferia parishii respectively. In leaf extract phytol (72.55±0.5%), hexadecanoic acid methyl ester (4.94±0.2%), hexahydro farnesyl acetone (3.78±0.2%), dibutyl phthalate (3.31±0.2%) were found to be the major constituents and those of rhizome extract were totarol (74.96±0.86%), cembrene (2.83±0.2%), borneol (1.23±0.15). Both the extracts exhibited low to moderate antioxidant activity. They possess very weak activities against some tested microorganisms while the extracts had no activity against some microorganisms.Conclusion: Totarol, an antimicrobial agent, was found to be the major constituent of Kaempferia parishii rhizome extract. Thus, Kaempferia parishii can be used as a natural source of totarol. This is the first report on the unexplored plant, Kaempferia parishii.Keywords: Kaempferia parishii, GC-MS analysis, Totarol, Phytol, Antioxidant activity, Antimicrobial activit

Immunogenic Modulations Induced by Prospective Anti-Malarial Herbal Extracts in Murine Model

Keeping in view the ever increasing problem of drug resistance and affordability of the antimalarial drugs by the poor mass, herbal medicines can become an important and alternative sustainable strategy for malaria treatment. Aqueous extracts of three Himalayan herbs― _Equisetum ravense_, _Artemisia vulgaris_ and _Centella asiatica_, with reported antimalarial property were screened for clinical efficacy against a local strain of _Plasmodium vivax_ antigen in murine model. _E. arvense_ extract was consistent in boosting phagocytic activity, nitric oxide generation, acid phosphatase and alkaline phosphatase activities in the peritoneal macrophages. The effectiveness of the rest herbals was discrete. A need for further detailed investigation to evaluate the clinical efficacy of these herbals seems essential