Thermoplastic polyurethane and nitrile butadiene rubber blends with layered double hydroxide nanocomposites by solution blending

Polymer blending coupled with nanofillers has been widely accepted as one of the cheaper methods to develop high‐performance polymeric materials for various applications. In the present work, dodecyl sulfate intercalated Mg? Al‐based layered double hydroxide (DS‐LDH) was used as nanofiller in the synthesis of polyurethane blended with nitrile butadiene rubber (PU/NBR; 1:1 w/w) nanocomposites, which were subsequently characterized. X‐ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the partial dispersion of Mg? Al layers in PU/NBR blends at lower filler content followed by aggregation at higher filler loading. In comparison to the neat PU/NBR blend, the tensile strength (156%) and elongation at break (21%) show maximum improvement for 1 wt% filler loading. The storage and loss moduli, thermal stability and limiting oxygen index of the nanocomposites are higher compared to the neat PU/NBR blend. Glass transition temperature and swelling measurements increase up to 3 wt% DS‐LDH loading in PU/NBR compared to either neat PU/NBR or its other corresponding nanocomposites. XRD and TEM analyses indicate the partial distribution of DS‐LDH in PU/NBR blends suggesting the formation of partially exfoliated nanocomposites. The improvements in mechanical, thermal and flame retardancy properties are much greater compared to the neat blend confirming the formation of high‐performance polymer nanocomposites. Copyright © 2009 Society of Chemical Industry     

Solid acid catalyzed synthesis of furans from carbohydrates

The alternative feedstock, biomass (particularly lignocelluloses), having the profuse availability, is promising for the synthesis of several value-added chemicals which are currently obtained from fossil feedstock. In this article, the synthesis of two extremely significant furan chemicals viz. furfural and 5-hydroxymethylfurfural (HMF) are discussed. In the synthesis of furans from biomass, numerous challenges, i.e., use of edible sugars as substrates, selectivity to furans, their isolation in pure form, reuse of catalyst, environmental issues, etc., are perceived and in the recent past researchers tried to resolve those by developing advance methodologies. This article comprehensively summarizes the latest progress made in the above-mentioned areas and also provides commentary on the analyses of results, rationale for observed activity and mechanisms, etc. It also discusses future aspects of this work.     

Eave Ice Dams

Water seepage into interior spaces and the resultant staining of wall and/or ceiling surfaces is a common problem with eave ice dams. If the outdoor temperature is below freezing, the roof is poorly insulated, and if the roof snow layer is thick enough, the temperature at the bottom of the snow will be at freezing. A portion of the thermal energy goes into melting some of the roof snow, that is, meltwater is generated which flows downslope toward the eaves. Some of the meltwater refreezes at the cold eave, forming an ice dam. The potential for water seepage is related to the horizontal extent of the ice dam. Mitigation usually involves placing an impermeable “ice and snow guard” layer for some distance from the eave. This paper presents information on the horizontal extent of expected eave ice dams with various returns period for 15 U.S. cities. In addition a correlation between ice dam size and the 50-year ground snow load is presented which allows one to estimate ice dam size for any U.S. city.     

Selective Zinc(II)‐Ion Fluorescence Sensing by a Functionalized Mesoporous Material Covalently Grafted with a Fluorescent Chromophore and Consequent Biological Applications

A highly ordered 2D‐hexagonal mesoporous silica material is functionalized with 3‐aminopropyltriethoxysilane. This organically modified mesoporous material is grafted with a dialdehyde fluorescent chromophore, 4‐methyl‐2,6‐diformyl phenol. Powder X‐ray diffraction, transmission electron microscopy, N₂ sorption, Fourier transform infrared spectroscopy, and UV‐visible absorption and emission have been employed to characterize the material. This material shows excellent selective Zn²⁺ sensing, which is due to the fluorophore moiety present at its surface. Fluorescence measurements reveal that the emission intensity of the Zn²⁺‐bound mesoporous material increases significantly upon addition of various concentrations of Zn²⁺, while the introduction of other biologically relevant (Ca²⁺, Mg²⁺, Na⁺, and K⁺) and environmentally hazardous transition‐metal ions results in either unchanged or weakened intensity. The enhancement of fluorescence is attributed to the strong covalent binding of Zn²⁺, evident from the large binding constant value (0.87 × 10⁴ M ^?1). Thus, this functionalized mesoporous material grafted with the fluorescent chromophore could monitor or recognize Zn²⁺ from a mixture of ions that contains Zn²⁺ even in trace amounts and can be considered as a selective fluorescent probe. We have examined the application of this mesoporous zinc(II) sensor to cultured living cells (A375 human melanoma and human cervical cancer cell, HeLa) by fluorescence microscopy.     

Sn-ZSM-12, a new,large pore MTW type tin-silicate molecular sieve: synthesis,characterization and catalytic properties in oxidation reactions

A new large pore tin-silicate analogue of zeolite ZSM-12 (MTW topology) with Si/Sn molar ratio >70 has been synthesized hydrothermally using a new template, hexamethylene bis(benzyl dimethyl ammonium hydroxide). This material exhibits an expansion in unit cell volume (XRD), an IR band at 970 cm^–1 and a charge transfer band at 205 nm in the UV-Vis region indicating the presence of Si-O-Sn units with Sn⁴⁺ centers in T_d configuration. Sn-ZSM-12 catalyzes the oxidation of phenol,m-cresol andm-xylene using dilute H₂O₂ as an oxidizing agent.     

Efficient E-beam excitation of XeCl

Efficient laser output at 308 nm has been obtained from XeCl in an Ne/Xe/HCl mixture at a pressure of 4 atm bye-beam excitation and bye-beam controlled discharge pumping. Maximum energy extraction is 7 J/1 fore-beam excitation and 9 J/1 for thee-beam controlled discharge. Efficiencies based on total energy deposited in the gas are approximately 4 percent. Similar results were obtained with KrF in the same device, indicating that undere-beam ore-beam controlled discharge excitation, XeCl may be as efficient as KrF.     

Rapid measurement of lifetime using a ramped mos capacitor transient

A modification of the Zerbst method is presented for the measurement of generation lifetime in MOS capacitors. In the new method, the voltage applied to the gate consists of a combination of a step and a ramp instead of just a step as in the case of the Zerbst method. This results in a considerable saving in the time taken to complete the measurement, which is a significant advantage when a large number of capacitors is being probed. The new method is especially suitable for a computer-aided measurement system. Experimental results using this method are presented and compared with the theoretical predictions.     

Analysing social behaviour and message dissemination in human based delay tolerant network

Recent advances in mobile communication shows proliferation in networks formed by human carried devices known as the pocket switched network (PSN). Human beings are social animals. They tend to form groups and communities, and have repetitive mobility pattern which can be used to disseminate information in PSNs. In this paper, we give a deeper insight to the nature of community formation and how such information can be used to help opportunistic forwarding in mobile opportunistic networks. Using real world mobility traces, we first derive the adjacency list for each node and form the contact graph. Using tools from social network analysis we then determine various node properties like centrality and clustering coefficient and graph properties like average path length and modularity. Based on the derived graph properties, node encounter process and nature of message dissemination in PSNs, we propose two social based routing, known as the contact based routing and community aware two-hop routing. We compare the proposed routing techniques with generic epidemic and prophet routing and Bubble-Rap, a social based routing. Results show that the proposed algorithms is able to achieve better delivery ratio and lower delay than Bubble Rap, while reducing the high overhead ratio of epidemic and prophet routing.     

Development of karanja oil based offset printing ink in comparison with linseed oil

The conventional offset lithographic printing ink is mainly based on linseed oil. But in recent years, due to stiff competition from synthetic substitutes mainly from petroleum products, the crop production shrinks down to an unsustainable level, which increases the price of linseed oil. Though soyabean oil has replaced a major portion of linseed oil, it is also necessary to develop alternate cost effective vegetable oils for printing ink industry. The present study aims to evaluate the performance of karanja oil (Pongamia glabra) as an alternative of linseed oil in the formulation of offset printing ink because karanja oil is easily available in rural India. Physical properties of raw karanja oil are measured and compared with that of alkali refined linseed oil. Rosin modified phenolic resin based varnishes were made with linseed oil as well as with karanja oil and their properties are compared. Sheetfed offset inks of process colour yellow and cyan is chosen to evaluate the effect of karanja oil in ink properties. In conclusion, karanja oil can be accepted as an alternate vegetable oil source with its noticeable effect on print and post print properties with slower drying time on paper. However, the colour and odour of the oil will restrict its usage on offset inks.