A microfluidic device for continuous capture and concentration of microorganisms from potable water

A microfluidic device based on electrophoretic transport and electrostatic trapping of charged particles has been developed for continuous capture and concentration of microorganisms from water. Reclaimed and bottled water samples at pH values ranging from 5.2-6.5 were seeded with bacteria (E. coli, Salmonella, and Pseudomonas) and viruses (MS-2 and Echovirus). Negative control and capture experiments were performed simultaneously using two identical devices. Culture based methods were utilized to characterize the capture efficiency as a function of the species type, time, flow rate, and applied electric field. Based on differences between the capture and negative control data, capture efficiencies of 90% to 99% are reported for E. coli, Salmonella, Pseudomonas, and MS-2, while the capture efficiency for Echovirus was between 70% and 80%. Overall, the device exhibits a 16.67 fold sample volume reduction within an hour at 6 mL h(-1) flow rate, resulting in a concentration factor of 14.2 at 85.2% capture efficiency. The device can function either as a filter or a sample concentrator without using any chemical additives. It can function as an integral component of a continuous, microbial capture and concentration system from large volumes of potable water.     

Compatibility and thermal decomposition kinetics between HMX and some polyester-based polyurethanes

Journal of Thermal Analysis and Calorimetry - A polyester (PE)-based polyurethane (PU) is widely used as a polymeric binder with an energetic compound especially more energetic octhydro-1,3,5,7...     

A Hexavalent Basket for Bottom-Up Construction of Functional Soft Materials and Polyvalent Drugs through a “Click” Reaction

Inspired by polyvalency and its prevalence in nature, we developed an efficient synthetic route for accessing a large variety of multivalent and dual-cavity baskets from inexpensive and abundant starting materials. First, the cycloaddition of vinyl acetate to anthracene was optimized to, upon hydrolysis, give dibenzobarrelene derivative 6 , which after five functional group transformations and then cyclotrimerization gave heptiptycene dodecaester 4 in an overall 17 % yield. Following that, compound 4 was converted into D_3h symmetric 1 , composed of two fused cavitands each holding three terminal alkynes at the rim for conjugation to functional molecules using the highly efficient CuAAC reaction. To survey the reactivity of hexavalent 1 , we “clicked” 2-acetamido-2-deoxy-β-d -glucopyranosyl azide 3,4,6-triacetate (carbohydrate), methoxypolyethylene glycol azide (PEG, M_n=2000; polymer) and benzyl azide (aromatic) to obtain hexavalent conjugates 12 – 14 in 50–79 % yields. In summary, dual-cavity 1 is an accessible, structurally-unique and hexavalent host that can be “clicked” to a variety of functional molecules for (a) combinatorial lead identification of drugs, (b) preparation of hierarchical soft materials and (c) design of selective chemosensors, scavengers, or supramolecular catalysts.     

Ionic conductivity through thermoresponsive polymer gel: ordering matters

Thermoreversible polymer gel has been prepared using PEO-PPO-PEO block copolymer (Pluronic F77) which self-assembles into different microcrystalline phases like cubic, 2D-hexagonal, and lamellar. Addition of electrolyte (LiI/I(2)) converts the gel into a polymer gel electrolyte (PGE) which exhibits microphase-dependent ionic conductivity. The crystalline phases have been identified by SAXS as a function of the polymer concentration. It is found that the optimum value for the ionic conductivity (≈1 × 10(-3) S x cm(-1)) is achieved in the Im3m phase due to faster diffusion of ions through the 3D-interconnected micellar nanochannels. This fact is further supported by FTIR study, ionic transference number, and diffusion coefficient measurements.     

Characterization of deep energy level defects in α-Al2O3:C using thermally assisted OSL

Commercially available α-Al₂O₃:C powder was studied for deep energy level defects by a newly suggested method using thermally assisted optically stimulated luminescence (TA-OSL) phenomenon. The method involves simultaneous application of continuous wave optically stimulated luminescence (CW-OSL) as well as thermal stimulation up to 400 °C, using a linear heating rate of 4 K/s. By using this method, two well-defined peaks at 121 °C and 232 °C were observed. These TA-OSL peaks have been correlated to two different types of deeper defects which can be bleached at 650 °C and 900 °C respectively on thermal treatment. These deeper defects, having larger thermal trap depth and relatively lower photoionization cross-section at room temperature for stimulation with blue LED (470 nm), are stable up to 500 °C, so they can store absorbed dose information even if the sample is inadvertently exposed to light or temperature. As only a fraction of signal is bleached during TA-OSL readout, multiple readouts could be performed on an exposed sample using this technique. The dose vs TA-OSL response from deep traps of α-Al₂O₃:C was found to be linear up to 10 kGy, thus extending its application for high dose dosimetry. The value of thermally assisted energy (E_A) associated with these traps in α-Al₂O₃:C has been determined to be 0.268 eV and 0.485 eV respectively and the corresponding values of photoionization cross-section at room temperature (25 °C), for optical stimulation with blue light (470 nm), are 5.82 × 10^?20 and 3.70 × 10^?22 cm², respectively. The process of thermally assisted OSL has been formulated analytically as well as theoretically for describing the temperature dependence of optical cross-section and evaluation of thermally assisted energy associated with deep traps.     

K→(ππ)(I=2) decay amplitude from lattice QCD

We report on the first realistic ab initio calculation of a hadronic weak decay, that of the amplitude A(2) for a kaon to decay into two π mesons with isospin 2. We find ReA(2)=(1.436±0.063(stat)±0.258(syst))10(-8) GeV in good agreement with the experimental result and for the hitherto unknown imaginary part we find ImA(2)=-(6.83±0.51(stat)±1.30(syst))10(-13) GeV. Moreover combining our result for ImA(2) with experimental values of ReA(2), ReA(0), and ε'/ε, we obtain the following value for the unknown ratio ImA(0)/ReA(0) within the standard model: ImA(0)/ReA(0)=-1.63(19)(stat)(20(syst)×10(-4). One consequence of these results is that the contribution from ImA(2) to the direct CP violation parameter ε' (the so-called Electroweak Penguin contribution) is Re(ε'/ε)(EWP)=-(6.52±0.49(stat)±1.24(syst))×10(-4). We explain why this calculation of A(2) represents a major milestone for lattice QCD and discuss the exciting prospects for a full quantitative understanding of CP violation in kaon decays.     

Synthesis, structural, spectral, thermal and antimicrobial studies of palladium(II), platinum(II), ruthenium(III) and iridium(III) complexes derived from N,N,N,N-tetradentate macrocyclic ligand

Palladium(II), platinum(II), ruthenium(III) and iridium(III) complexes of general stoichiometry [PdL]Cl(2), [PtL]Cl(2), [Ru(L)Cl(2)]Cl and [Ir(L)Cl(2)]Cl are synthesized with a tetradentate macrocyclic ligand, derived from 2,6-diaminopyridine with 3-ethyl 2,4-pentanedione. Ligand was characterized on the basis of elemental analyses, IR, mass, and (1)H NMR and (13)C NMR spectral studies. All the complexes were characterized by elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, mass, electronic spectral techniques and thermal studies. The value of magnetic moments indicates that all the complexes are diamagnetic except Ru(III) complex which shows magnetic moments corresponding its one unpaired electron. The macrocyclic ligand and all its metal complexes were also evaluated in vitro against some plant pathogenic fungi and bacteria to assess their biocidal properties.     

Structure and vibrational spectra of some 8-oxa[5]helicenes

A systematic study has been conducted on the geometrical and electronic structure, heliomeric conformations of a series of 8-oxa[5]helicenes based on density functional theory (DFT) computations. A complete vibrational analysis has also been attempted for one of the 8-oxa[5]helicenes (molecule 5) on the basis of experimental infrared spectra in the far and mid infrared regions (60-3100 cm(-1)) and density functional theory computations using B3LYP/6-31G** method characteristic bands of the molecule identified. The approximate mean plane angle between the terminal rings A and E in the presently studied molecules are found to have values between 48.64° and 59.46°. This angle is much larger than the corresponding angle between the terminal rings in benzo[c]phenanthrene (～27°) and partially reduced benzo[c]phenanthrene (34.6-46.0°) and indicates that the presence of oxygen-containing six-membered ring provides a greater helicity to the molecules. Detailed quantum chemical study on molecule 4 shows the existence of two enantiomeric forms M- and P- of almost equal energy separated by a potential barrier of 15.55 kcal/mol. It is expected that similar 8-oxa[5]helicines (molecules 3, 5 and 6) may also exist in two enantiomeric forms.