Focus point SUSY at the LHC revisited

The estimation of the backgrounds for gluino signals in focus point supersymmetry is extended by including the backgrounds from the production of four third generation quarks in the analysis. We find that these backgrounds are negligible if one uses the strong selection criteria proposed in the literature (including this analysis) for heavy gluino searches. Softer selection criteria often recommended for lighter gluino searches yield backgrounds that are small but numerically significant. We have also repeated the more conventional background calculations and compared our results with the other groups. We find that the size of the total residual background estimated by different groups using different event generators and hard kinematical cuts agree approximately. In view of the theoretical uncertainties in the leading order signal and background cross sections mainly due to the choice of the QCD scale, the gluino mass reach at the LHC cannot be pinpointed. However, requiring a signal with ≥3 tagged b-jets (instead of the standard choice of ≥2) it is shown that gluino masses close to 2 TeV can be probed at the LHC for a range of reasonable choices of the QCD scale for an integrated luminosity of 300 fb^-1. PACS 11.30.Pb; 12.60.Jv; 14.80.Ly; 95.35.+d     

Ni–Zn ferrite-loaded superparamagnetic amorphous carbon nanotubes through a facile route

Partial filling of mixed ferrite (Ni_0.5Zn_0.5Fe₂O₄; NZFO) nanoparticles into the amorphous carbon nanotubes (aCNTs) cavity is achieved by simple mixing of the aqueous dispersions of the two (aCNTs and NZFO) at room temperature. The process of incorporation of the nanoparticles into the aCNT cavity is solely mediated by the capillary action of the liquid. NZFO nanoparticles were homogeneously dispersed in the aqueous solution but after mixing they are sparsely distributed into the aCNT channel as a result of the capillary action. The encapsulation of the nanoparticles into the aCNTs amorphous shield was established by means of X-ray diffraction, transmission electron microscopy, Fourier transformed infrared spectroscopy, and Raman spectroscopic analysis. Such entrapment of the nanoparticles causes the composite nanotubes superparamagnetic in nature with blocking temperature (T _B) at 15 K. However, compared to the powder NZFO nanoparticles, T _B appears more sharply and at relatively lower temperature. Low filling density and the spatial confinement of the nanoparticles lessen the inter-particle interactions and the polydispersity within the NZFO nanoparticles which are manifested in their altered magnetic behavior.     

Towards the total synthesis of tashironin related allo-cedrane natural products: further exploitation of the oxidative dearomatization-IMDA-RCM triad based strategy

Synthetic studies directed towards allo-cedrane based, tashironin sibling natural products, involving some deft functional group manipulations on a preformed tetracyclic scaffold, are delineated.     

Restriction of Molecular Twisting on a Gold Nanoparticle Surface

To understand the photophysical properties of intramolecular charge transfer (ICT) and twisted intramolecular charge transfer (TICT) states on a gold nanoparticle (Au NP) surface, we have designed and synthesized a new coumarin molecule (C3) that exists both as ICT and TICT states in its excited state in a polar environment. On a Au NP surface, an excited C3 molecule only exists as an ICT state owing to restricted molecular rotation of a diethylamino group; as a result, no conversion from the ICT to TICT state was observed. Selection of the preferential state of a molecule with dual emitting states can be helpful for selected biological applications.     

α-Helix-Mimetic Foldamers for Targeting HIV-1 TAR RNA

An oligopyridylamide-based foldamer approach has been employed to target HIV TAR RNA-TAT assembly as a model system to study RNA-protein interactions. The oligopyridylamide scaffold adopts a constrained conformation which presents surface functionalities at distinct spatial locations and mimic the chemical features of the secondary structure of proteins. We have designed a library of oligopyridylamides containing diverse surface functionalities which mimic the side chain residues of the TAT protein domain. The interaction of TAR RNA and TAT plays a pivotal role in facilitating HIV replication. The library was screened using various fluorescent based assays to identify antagonists of the TAR RNA-TAT complex. A tricationic oligopyridylamide ADH-19, possessed the highest affinity towards TAR and efficiently inhibited the TAR RNA-TAT interaction with apparent K_d of 4.1±1.0 μm . Spectroscopic studies demonstrated that ADH-19 interacts with the bulge and the lower bulge regions of TAR RNA, the domains important for TAT interaction. ADH-19 demonstrated appreciable in vivo efficacy (IC₅₀=25±1 μm ) by rescuing TZM-bl cells infected with the pseudovirus HIV-1HXB-2.     

On quasi completely regular semirings

We extend the concepts of a completely π-regular semigroup and a GV semigroup to semirings and find a semiring analogue of a structure theorem on GV semigroups. We also show that a semiring S is quasi completely regular if and only if S is an idempotent semiring of quasi skew-rings.     

Single chemosensor for highly selective colorimetric and fluorometric dual sensing of Cu(II) as well as ‘NIRF’ to acetate ion

A novel fluorescent probe for the copper(II) ion in mixed aqueous media, based on fluorescence quenching mechanism with noticeable color change from light to dark yellow, was designed and synthesized. It also exhibited high selectivity for acetate in acetonitrile over other common anions in the near infrared region (NIR) accompanied with exciting color changes from light yellow to pink. Hence sensor 1 ascertains its dual chemosensing ability toward Cu(II) and acetate ions as evidenced by competitive experiments.     

Estimation of distribution coefficient of uranium around a uranium mining site

Distribution coefficient (K _d) of uranium and its daughter products are very important for migration study around uranium mining sites. Since the distribution coefficient depends very much on the soil and groundwater chemistry, generation of site specific K _d is very important. In the literature there is a large variation of K _d values of uranium. For realistic prediction of contaminant migration, literature K _d value is not very effective. So site specific experimental K _d values are required. The present study emphasizes on the estimation of site specific distribution coefficient for uranium around a uranium mining site. The soil and groundwater parameters which affect the K _d value of uranium have also been estimated. Soil and groundwater samples from nine locations around Turamdih uranium mining site were collected and chemically characterized for various parameters. The distribution coefficient of uranium in top and one meter depth soil samples from above locations were estimated using laboratory batch method. The distribution coefficient of uranium varies from 69 ± 4 to 5524 ± 285 l/kg. No significant difference in uranium K _d values was observed for top and one meter depth soil samples. In the top and one meter depth soil samples uranium K _d values vary from 129 ± 8 to 5524 ± 285 and 69 ± 4 to 3862 ± 195 l/kg respectively. For the estimation of distribution coefficient of uranium different parameters like equilibration time, solid to solution ratio, method of tracer addition to solution, solid-solution separation method etc. have been optimized. The distribution coefficient of uranium determined in the present study will be used for the migration study of uranium around uranium mining sites.     

Remarkable Regioisomer Control in the Hydrogel Formation from a Two‐Component Mixture of Pyridine‐End Oligo(p‐phenylenevinylene)s and N‐Decanoyl‐L‐alanine

N‐Decanoyl‐L ‐alanine (DA) was mixed with either colorless 4,4′‐bipyridine (BP) or various derivatives such as chromogenic oligo(p‐phenylenevinylene) (OPV) functionalized with isomeric pyridine termini in specific molar ratios. This mixtures form salt‐type gels in a water/ethanol (2:1, v/v) mixture. The gelation properties of these two‐component mixtures could be modulated by variation of the position of the ′′N′′ atom of the end pyridyl groups in OPVs. The presence of acid–base interactions in the self‐assembly of these two‐component systems leading to gelation was probed in detail by using stoichiometry‐dependent UV/Vis and FTIR spectroscopy. Furthermore, temperature‐dependent UV/Vis and fluorescence spectroscopy clearly demonstrated a J‐type aggregation mode of these gelator molecules during the sol‐to‐gel transition process. Morphological features and the arrangement of the molecules in the gels were examined by using scanning electron microscopy (SEM), atomic force microscopy (AFM), and X‐ray diffraction (XRD) techniques. Calculation of the length of each molecular system by energy minimization in its extended conformation and comparison with the XRD patterns revealed that this class of gelator molecules adopts lamellar organizations. Rheological properties of these two‐component systems provided clear evidence that the flow behavior could be modulated by varying the acid/amine ratio. Polarized optical microscopy (POM), differential scanning calorimetry (DSC), and XRD results revealed that the solid‐phase behavior of such two‐component mixtures (acid/base=2:1) varied significantly upon changing the proton‐acceptor part from BP to OPV. Interestingly, the XRD pattern of these acid/base mixtures after annealing at their associated isotropic temperature was significantly different from that of their xerogels.