Fluctuation study of pionisation in ultrarelativistic nucleus-nucleus interaction

The scaled factorial moments and the multifractal moments have been investigated in different??-intervals to study the dynamical fluctuation of pions produced in 200 AGeV³²S-Ag/Br interaction. In order to investigate the detail characteristics of intermittency behaviour, theF-moments are extracted up to the eighth order of moments in differentM-intervals. The analysis indicates a non-thermal phase transition and different regime of particle production during the hadronisation process.     

Selective Interpolymer Complexation between Acrylic Copolymers and Nonionic Polymers

Abstract

Selective interpolymer complexation has been studied between methacrylic acid-methacrylamide copolymer and some complementary polymers such as poly(methacrylamide), poly(vinyl pyrrolidone), and poly(ethylene oxide). The relative order of complexation ability of the various nonionic polymers has been interpreted on the basis of the nature of interactions between different units of polymers. Configurational environment and neighboring group influences seem to affect interpolymer complex formation.     

Influence of Grafted Chain Length of a Phenolic Copolymer on Its Complex Formation with Poly(vinyl Pyrrolidone) and Poly(ethylene Oxide)

A phenolic copolymer has been grafted with oligomers of different chain lengths. Polymer-polymer complexation has been studied between graft copolymers and nonionic polymers, such as polyvinyl pyrrolidone) and poly(ethylene oxide), in an acetone-methanol mixture by several methods, e.g., viscosity, conductance, and apparent pH measurements. A distinct stepwise complexation between PVP and graft copolymers has been observed. The length of the side chain also seemed to influence interpolymer complex formation. Some of these observations have been interpreted with reference to the actual structure of the graft copolymers.     

Grafting on Some Phenolic Copolymer Chains

A phenolic copolymer has been prepared by copolymerization of p-chlorophenol, p-cresol, and formaldehyde in the presence of acid catalyst. The copolymer was partially and completely dehalogenated by a standard method. The dehalogenated copolymer chain had a random distribution of reactive positions which were originally occupied by Cl atoms. Some substituted monomers, oligomers of known structure and molecular weight, and basic polymer chains have been grafted at these reactive positions. The halogen percentage of the grafted copolymers could be calculated on the assumption that all the available reactive positions are attached to the respective units. Reasonably good agreement has been found between the calculated and observed amount of halogen percentage in the grafted copolymers.     

Association reaction between SiH3 and H2O2: a computational study of the reaction mechanism and kinetics

The association reaction between silyl radical (SiH₃) and H₂O₂ has been studied in detail using high-level composite ab initio CBS-QB3 and G4MP2 methods. The global hybrid meta-GGA M06 and M06-2X density functionals in conjunction with 6-311++G(d,p) basis set have also been applied. To understand the kinetics, variational transition-state theory calculation is performed on the first association step, and successive unimolecular reactions are subjected to Rice–Ramsperger–Kassel–Marcus calculations to predict the reaction rate constants and product branching ratios. The bimolecular rate constant for SiH₃–H₂O₂ association in the temperature range 250–600 K, k(T) = 6.89 × 10^?13 T ^?0.163exp(?0.22/RT) cm³ molecule^?1 s^?1 agrees well with the current literature. The OH production channel, which was experimentally found to be a minor one, is confirmed by the rate constants and branching ratios. Also, the correlation between our theoretical work and experimental literature is established. The production of SiO via secondary reactions is calculated to be one of the major reaction channels from highly stabilized adducts. The H-loss pathway, i.e., SiH₂(OH)₂ + H, is the major decomposition channel followed by secondary dissociation leading to SiO.     

Molecularly imprinted polyaniline-polyvinyl sulphonic acid composite based sensor for para-nitrophenol detection

We report results of the studies relating to the fabrication and characterization of a conducting polymer based molecularly imprinted para-nitrophenol (PNP) sensor. A water pollutant, para-nitrophenol is electrochemically imprinted with polyvinyl sulphonic acid (PVSA) doped polyaniline onto indium tin oxide (ITO) glass substrate. This PNP imprinted electrode (PNPI-PANI-PVSA/ITO) prepared via chronopotentiometric polymerization and over-oxidation is characterized by Fourier transform infra-red spectroscopy (FT-IR), UV–visible (UV–vis) spectroscopy, contact angle (CA), scanning electron microscopy (SEM), cyclic voltammetry (CV) and differential pulse voltammetry (DPV) studies. The response studies of PNPI-PANI-PVSA/ITO electrode carried out using DPV reveal a lower detection limit of 1 × 10⁻³ mM, improved sensitivity as 1.5 × 10⁻³ A mM⁻¹ and stability of 45 days. The PNPI-PANI-PVSA/ITO electrode shows good precision with relative standard deviation of 2.1% and good reproducibility with standard deviation of 3.78%.     

Immunomagnetic nanoparticle based quantitative PCR for rapid detection of Salmonella

We have developed a rapid and sensitive method for immunomagnetic separation (IMS) of Salmonella along with their real time detection via PCR. Silica-coated magnetic nanoparticles were functionalized with carboxy groups to which anti-Salmonella antibody raised against heat-inactivated whole cells of Salmonella were covalently attached. The immuno-captured target cells were detected in beverages like milk and lemon juice by multiplex PCR and real time PCR with a detection limit of 10⁴ cfu.mL^?1 and 10³ cfu.mL^?1, respectively. We demonstrate that IMS can be used for selective concentration of target bacteria from beverages for subsequent use in PCR detection. PCR also enables differentiation of Salmonella typhi and Salmonella paratyphi A using a set of four specific primers. In addition, IMS—PCR can be used as a screening tool in the food and beverage industry for the detection of Salmonella within 3–4 h which compares favorably to the time of several days that is needed in case of conventional detection based on culture and biochemical methods.

Cyclisation of Ortho -Cyclohexenyl Phenols via Epoxidation #

A number of ortho -cyclohexenyl phenols 2(a–i) have been cyclised by treatment with one equivalent of m-chloroper-oxybenzoic acid in refluxing benzene for 4 h to furnish linearly fused 1-hydroxy-1,2,3,4,4a,9a-hexahydrodibenzofurans 3(a–i) (70–80%) and bicyclic 3-hydroxy-1,3-ethanochromans 4(a–f) (10–20%). Products 3(a–i) were oxidised with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (excess) in refluxing dry xylene for 6 h to give 2,3-dihydrodibenzofuran-1 (2H)-ones 6(a–i) (85–95%).

     

A Mild and Efficient Route to 3-Vinylchromones in Aqueous Micellar Media

A simple, mild, and ecofriendly method has been developed for the synthesis of 3-vinylchromones from 4-oxo-4H-1-benzopyran-3-carboxaldehyde (3-formylchromone) by simple Knoevenagel condensation with various active methylene compounds (AMC) in aqueous micellar media in the presence of catalytic amounts of cetyl trimethylammonium bromide (CTAB) and 1,4-diazabicyclo[2.2.2]octane (DABCO). In the case of malonic acid as AMC, the reaction resulted in formation of only Doebner decarboxylated products under the standard reaction condition. It has been also observed that 3-formylchromone derivatives primarily undergo tandem Knoevenagel and Michael reactions in the presence of > 2 equiv. of ethyl acetoacetate to produce benzophenone derivatives, by opening of pyran ring, as the sole product in good yields.