Studies on brackish water epiphytic algae from Sundarbans in North 24 Parganas district, West Bengal, India

This study represents the species diversity and ecology of brackish water epiphyticalgae of Sundarbans. Out of 22 taxa, Cyanophyceae represent 50%, Chlorophyceae and Xanthophyceae were 36% and 14%, respectively. These algal taxa were studied in relationto physicochemical characters viz. water temperature, transparency, pH, salinity,phosphate and nitrate. To analyze the data, computerized statistical package was used tocalculate correlation co-efficient between the epiphytic algal distribution andphysicochemical factors. A dendrogram was also constructed to reveal the relationshipsamong different algae on the basis of their diversity in different seasons. Epiphytic algaltaxa showed maximum growth during summer and are more diverse and variable atdifferent stations. These taxa showed a correlation with the habitat

Minimization of Handoff Failure Probability for Next-Generation Wireless Systems

During the past few years, advances in mobile communication theory have enabled the development and deployment of different wireless technologies, complementary to each other. Hence, their integration can realize a unified wireless system that has the best features of the individual networks. Next-Generation Wireless Systems (NGWS) integrate different wireless systems, each of which is optimized for some specific services and coverage area to provide ubiquitous communications to the mobile users. In this paper, we propose to enhance the handoff performance of mobile IP in wireless IP networks by reducing the false handoff probability in the NGWS handoff management protocol. Based on the information of false handoff probability, we analyze its effect on mobile speed and handoff signaling delay.Comment: 16 Page

Type I singularities and the Phantom Menace

We consider the future dynamics of a transient phantom dominated phase of the universe in LQC and in the RS braneworld, which both have a non-standard Friedmann equation. We find that for a certain class of potentials, the Hubble parameter oscillates with simple harmonic motion in the LQC case and therefore avoids any future singularity. For more general potentials we find that damping effects eventually lead to the Hubble parameter becoming constant. On the other hand in the braneworld case we find that although the type I singularity can be avoided, the scale factor still diverges at late times.Comment: More references added. Final PRD versio

Development of NR/SBR Based Rubber Compounds with Low Hysteresis and High Durability for Transmission V-Belts Applications

Power transmission by the belts is defined as, the transmission of power by a moving pulley to one or more driven machines through a flexible non-metallic member. There are different types of V-belts available,and Transmission Belts are one of them. Transmission V-Belt is the first invented non-metallic belts. Nowadays V-belts are used in various conditions, especially high-power transmission. These V-belts are finding their importance in many heavy industries. One of the good features of this type belt is no slippage occurs during the run. NR and SBR have used elastomers and can act as a base rubber material for this purpose. This study includes the compounding improvement for transmission V-Belts with NR and SBR rubber blends. There were so many numbers of failures in different ways during the initial research. Product failure methods and effect analysis (PFMA) have done by testing the belts multiple times and it has found that the major factors for the failure and less durability were excessive heat build-up (HBU) and poor fatigue resistance, poor crack initiation and growth, the resistance of the materials. So, initially reduction of HBU has successfully made in many steps by studying the properties of various compounds with a different type of fillers combinations, rubber combinations, curing systems variations etc. We have also improved the adhesion strength with cord and fabrics. Initially, we have taken one compound showing better properties in all aspects and have taken Belt Trial. And after some more improvement, we have found a compound showing better properties in all the cases than first trial and regular trials.By using that compound, we have developed Belts and showing better durability than earlier experiments and regular production

Exploring the influence of electron beam crosslinking in SEBS/TPU and SEBS-g-MA/TPU thermoplastic elastomer blends

The effects of electron beam (EB) radiation in thermoplastic elastomers based on SEBS/TPU and SEBS-g-MA/TPU are evaluated. 60/40 blend of both the systems were subjected to EB using an ILU type industrial accelerator. Radiation dose was varied from 0 to 100 kGy, and the sol–gel content evaluation along with detailed analysis of mechanical, thermal, rheological, and morphological implications was conducted. The interplay between crosslinking and chain scission was quantified using the Charlesby-Pinner equation. Both the blends showed the presence of a three-dimensional cross-linked network in them after the irradiation. The tensile strength of SEBS/TPU was found to deteriorate with an increase in radiation dose, but an opposite trend was observed in SEBS-g-MA/TPU. Improvement in interfacial adhesion between SEBS-g-MA and TPU was confirmed. The morphological analysis through atomic force microscopy and scanning electron microscopy clearly showed the appearance of rough ridges and pits due to irradiation along with the cross-linked networks. From differential scanning calorimetry analysis, the changes in glass transitions and melting endotherm were assessed. Thermogravimetric analysis results indicated an improvement in the thermal stability of the blends. The storage modulus and complex viscosity of the samples enhanced as perceived from the rheological measurements. X-ray diffraction patterns of the blends also showed considerable variation after irradiation

Exploring the thermomechanical properties of peroxide/co-agent assisted thermoplastic vulcanizates through temperature scanning stress relaxation measurements

Temperature scanning stress relaxation (TSSR) measurement of peroxide vulcanized polymer blends of polypropylene (PP) and ultrahigh molecular-EPDM (UHM-EPDM) rubber has been performed to study the thermomechanical behavior of thermoplastic vulcanizates (TPVs). Co-agents play crucial roles in the enhancement of properties of TPVs. Different types of co-agents (Triallyl cyanurate-TAC; N, N-m-phenylene-dimaleimide-HVA2; zinc dimethacrylate-ZDMA; and in-situ formed zinc dimethacrylate-ZMA) have been explored in this work. TSSR study shows that higher T50 and T90 values have been achieved in ZMA co-agent assisted-TPV. Higher TSSR-index (RI) value was also found for the same co-agent ZMA, indicating higher elastic behavior. TSSR result supports the mechanical and rheological properties, and it is found that the ZMA and ZDMA show higher mechanical strength. Cross-linked-density calculated by modified Flory–Rehner equation and the cross-link-density as obtained from TSSR method have been compared and the trend was found to be the same. Stress relaxation study shows the slow relaxation-phenomena of the ZMA-TPV with slowest relaxation-time (θr) than the other TPVs, which correlates with superior material strength. Thermogravimetric analysis proves that there is a difference in degradation temperature of the blends at approximately 5–10°C. Ultrahigh molecular weight-EPDM/PP based TPVs reveal superior thermomechanical and physico-mechanical properties with ZMA and ZDMA co-agent over TAC and HVA2. These ultrahigh molecular weight-EPDM based TPVs can be used in automotive seals/strips, hoses, bellows, and 2 K-molds for automotive applications

Phase transfer of 1- and 2-dimensional Cd-based nanocrystals

In this work, luminescent CdSe@CdS dot-in-rod nanocrystals, CdSe@CdS/ZnS nanorods as well as CdSe–CdS core–crown nanoplatelets were transferred into aqueous phase via ligand exchange reactions. For this purpose, bifunctional thiol-based ligands were employed, namely mercaptoacetic acid (MAA), 3-mercaptopropionic acid (MPA), 11-mercaptoundecanoic acid (MUA) as well as 2-(dimethylamino)ethanthiol (DMAET). Systematic investigations by means of photoluminescence quantum yield measurements as well as photoluminescence decay measurements have shown that the luminescence properties of the transferred nanostructures are affected by hole traps (induced by the thiol ligands themselves) as well as by spatial insulation and passivation against the environment. The influence of the tips of the nanorods on the luminescence is, however, insignificant. Accordingly, different ligands yield optimum results for different nanoparticle samples, mainly depending on the inorganic passivation of the respective samples. In case of CdSe@CdS nanorods, the highest emission intensities have been obtained by using short-chain ligands for the transfer preserving more than 50% of the pristine quantum yield of the hydrophobic nanorods. As opposed to this, the best possible quantum efficiency for the CdSe@CdS/ZnS nanorods has been achieved via MUA. The gained knowledge could be applied to transfer for the first time 2-dimensional CdSe–CdS core–crown nanoplatelets into water while preserving significant photoluminescence (up to 12% quantum efficiency).Volkswagen foundation/ZN2916BMBF/NanoMatFutur/03X5525Hannover School for NanotechnologyDFG/DO1580/2-1DFG/DO1580/3-1

Understanding the role of surfactants on the preparation of ZnS nanocrystals

We have synthesized surface modified ZnS nanoparticles of size 2–3 nm using non-ionic surfactant-stabilized reverse emulsions. The non-ionic surfactants in the Span series, i.e. sorbitan monolaurate (Span 20) and sorbitan monooleate (Span 80) of hydrophilic–lipophilic balance (HLB) values of 8.6 and 4.3, respectively, have been used for the stabilization of emulsions. The role of these surfactants in controlling the size and properties of the ZnS nanoparticles has been discussed. The triethylamine (TEA) has been proved to be the effective surface modifying (capping) agent for the preparation of free-standing ZnS nanoparticles. The Span 20 with the higher HLB value of 8.6 has been found to be highly suitable in synthesizing TEA-capped ZnS nanoparticles of smaller size and higher photophysical characteristics compared to that of the Span 80 of lower HLB value of 4.3. A mechanism for the formation of TEA-capped ZnS nanoparticles from the surfactant-stabilized reverse emulsions has been proposed