Non-gravitating scalar field in the FRW background

We study interacting scalar field theory non-minimally coupled to gravity in the FRW background. We show that for a specific choice of interaction terms, the energy–momentum tensor of the scalar field ϕ vanishes, and as a result the scalar field does not gravitate. The naive space dependent solution to equations of motion gives rise to singular field profile. We carefully analyze the energy–momentum tensor for such a solution and show that the singularity of the solution gives a subtle contribution to the energy–momentum tensor. The space dependent solution therefore is not non-gravitating. Our conclusion is applicable to other space–time dependent non-gravitating solutions as well. We study hybrid inflation scenario in this model when purely time dependent non-gravitating field is coupled to another scalar field χ.     

Geometric phase of a qubit interacting with a squeezed-thermal bath

We study the geometric phase of an open two-level quantum system under the influence of a squeezed, thermal environment for both non-dissipative as well as dissipative system-environment interactions. In the non-dissipative case, squeezing is found to have a similar influence as temperature, of suppressing geometric phase, while in the dissipative case, squeezing tends to counteract the suppressive influence of temperature in certain regimes. Thus, an interesting feature that emerges from our work is the contrast in the interplay between squeezing and thermal effects in non-dissipative and dissipative interactions. This can be useful for the practical implementation of geometric quantum information processing. By interpreting the open quantum effects as noisy channels, we make the connection between geometric phase and quantum noise processes familiar from quantum information theory.     

Alkali earth metal (Ca, Sr, Ba) based thermostable metal-organic frameworks (MOFs) for proton conduction

Three new alkaline earth metal based MOFs have been synthesized by using 4,4'-sulfobisbenzoic acid (SBBA) and alkaline earth metal salts M(NO(3))(2), M = Ca, Sr, Ba. These MOFs exhibit interesting structural diversity, variable chemical stability as well as proton conductivity.     

A naphthalene exciplex based Al3+ selective on-type fluorescent probe for living cells at the physiological pH range: experimental and computational studies

2-((Naphthalen-6-yl)methylthio)ethanol (HL) was prepared by one pot synthesis using 2-mercaptoethanol and 2-bromomethylnaphthalene. It was found to be a highly selective fluorescent sensor for Al(3+) in the physiological pH (pH 7.0-8.0). It could sense Al(3+) bound to cells through fluorescence microscopy. Metal ions like Mn(2+), Fe(3+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Ag(+), Cd(2+), Hg(2+), Cr(3+) and Pb(2+) did not interfere. No interference was also observed with anions like Cl(-), Br(-), F(-), SO(4)(2-), NO(3)(-), CO(3)(2-), HPO(4)(2-) and SCN(-). Experimentally observed structural and spectroscopic features of HL and its Al(3+) complex have been substantiated by computational calculations using density functional theory (DFT) and time dependent density functional theory (TDDFT).     

Formulation and radiochemical evaluation of a freeze-dried mixed peptide kit for the preparation of 68Ga-labeled peptides for PET imaging of somatostatin receptor positive neuroendocrine cancers

⁶⁸Ga-labeled DOTA-coupled somatostatin analogue peptides are regularly being used for the PET imaging of patients suspected to be suffering from various types of neuroendocrine cancers over-expressing somatostatin receptors. The article describes the formulation of a freeze-dried mixed peptide kit containing equal amounts of DOTA-TATE and DOTA-NOC and the radiochemical evaluation of the kit for the easy and convenient preparation of ⁶⁸Ga-labeled mixed radiopeptides. The simultaneous use of two different peptides in the kit is expected to perceive more cancerous lesions and may have a wider applicability in the diagnosis of neuroendocrine cancers.     

Mechanical Downsizing of a Gadolinium(III)‐based Metal–Organic Framework for Anticancer Drug Delivery

A Gd^III‐based porous metal–organic framework (MOF), Gd‐pDBI, has been synthesized using fluorescent linker pDBI (pDBI=(1,4‐bis(5‐carboxy‐1H‐benzimidazole‐2‐yl)benzene)), resulting in a three‐dimensional interpenetrated structure with a one‐dimensional open channel (1.9×1.2 nm) filled with hydrogen‐bonded water assemblies. Gd‐pDBI exhibits high thermal stability, porosity, excellent water stability, along with organic‐solvent and mild acid and base stability with retention of crystallinity. Gd‐pDBI was transformed to the nanoscale regime (ca. 140 nm) by mechanical grinding to yield MG‐Gd‐pDBI with excellent water dispersibility (>90 min), maintaining its porosity and crystallinity. In vitro and in vivo studies on MG‐Gd‐pDBI revealed its low blood toxicity and highest drug loading (12 wt %) of anticancer drug doxorubicin in MOFs reported to date with pH‐responsive cancer‐cell‐specific drug release.     

Ultrafast FRET to Study Spontaneous Micelle‐to‐Vesicle Transitions in an Aqueous Mixed Surface‐Active Ionic‐Liquid System

The spontaneous micelle‐to‐vesicle transition in an aqueous mixture of two surface‐active ionic liquids (SAILs), namely, 1‐butyl‐3‐methylimidazolium n‐octylsulfate ([C₄mim][C₈SO₄]) and 1‐dodecyl‐3‐methylimidazoium chloride ([C₁₂mim]Cl) is described. In addition to detailed structural characterization obtained by using dynamic light scattering, transmission electron microscopy (TEM), and cryogenic TEM techniques, ultrafast fluorescence resonance energy transfer (FRET) from coumarin 153 (C153) as a donor (D) to rhodamine 6G (R6G) as an acceptor (A) is also used to study micelle–vesicle transitions in the present system. Structural transitions of SAIL micelles ([C₄mim][C₈SO₄] or [C₁₂mim]Cl micelles) to mixed SAIL vesicles resulted in significantly increased D –A distances, and therefore, increased timescale of FRET. In [C₄mim][C₈SO₄] micelles, FRET between C153 and R6G occurs on an ultrafast timescale of 3.3 ps, which corresponds to a D –A distance of about 15 Å. As [C₄mim][C₈SO₄] micelles are transformed into mixed micelles upon the addition of a 0.25 molar fraction of [C₁₂mim]Cl, the timescale of FRET increases to 300 ps, which suggests an increase in the D –A distance to 31 Å. At a 0.5 molar fraction of [C₁₂mim]Cl, unilamellar vesicles are formed in which FRET occurs on multiple timescales of about 250 and 2100 ps, which correspond to D –A distances of 33 and 47 Å. Although in micelles and mixed micelles the obtained D –A distances are well correlated with their radius, in vesicles the obtained D –A distance is within the range of the bilayer thickness.     

Spark-induced agglomeration of aqueous polymeric suspensions

Discharging a high-energy spark underwater creates a shock wave that dissipates through an acoustic field. Colloidal acrylate polymers suspended in water containing dissolved calcium are agglomerated as a result. The degree of agglomeration increases with the number of sparks applied and with increasing calcium content. The calcium decreases the charge on the colloidal particles and thereby increases their propensity to be agglomerated by the acoustic wave. These observations are confirmed in full-scale trials in paper recycling mills where sparking improves the efficiency of centrifugal cleaners by increasing the particle size of the contaminants.     

Synthesis and stereoselective glycosylation of D- and L-glycero-beta-D-manno-heptopyranoses

[reaction: see text] A method for the direct stereocontrolled synthesis of D- and L-glycero-beta-D-manno-heptopyranosides such as those found in the repeating unit of the O-specific polysaccharide from the CNCTC 113/92 LPS (serotype 54) is described. The method relies on the presence of a 4,6-O-benzylidene acetal to effect stereocontrol at the anomeric center; the configuration at C6 (L- or D-glycero) is of minimal importance.