Enhanced durability of Li-O2 batteries employing vertically standing Ti nanowire array supported cathodes

Ti nanowire arrays vertically standing on Ti foam prepared by a facile corrosion method were used as self-supported Li-O₂ battery cathodes. The batteries exhibited enhanced durability at high rate current densities (e.g. cycling 640 times at 5 A g^-1).

CoO nanoparticles embedded in three-dimensional nitrogen/sulfur co-doped carbon nanofiber networks as a bifunctional catalyst for oxygen reduction/evolution reactions

High-performance and low-cost bifunctional electrocatalysts play crucial roles in oxygen reduction and evolution reactions. Herein, a novel three-dimensional (3D) bifunctional electrocatalyst was prepared by embedding CoO nanoparticles into nitrogen and sulfur co-doped carbon nanofiber networks (denoted as CoO@N/S-CNF) through a facile approach. The carbon nanofiber networks were derived from a nanostructured biological material which provided abundant functional groups to nucleate and anchor nanoparticles while retaining its interconnected 3D porous structure. The composite possesses a high specific surface area and graphitization degree, which favors both mass transport and charge transfer for electrochemical reaction. The CoO@N/S-CNF not only exhibits highly efficient catalytic activity towards oxygen reduction reaction (ORR) in alkaline media with an onset potential of about 0.84 V, but also shows better stability and stronger resistance to methanol than Pt/C. Furthermore, it only needs an overpotential of 1.55 V to achieve a current density of 10 mA cm^-2, suggesting that it is an efficient electrocatalyst for oxygen evolution reaction (OER). The ΔE value (oxygen electrode activity parameter) of CoO@N/S-CNF is calculated to be 0.828 V, which demonstrates that the composite could be a promising bifunctional electrocatalyst for both ORR and OER.

An effective three-dimensional ordered mesoporous CuCo2O4 as electrocatalyst for Li-O2 batteries

Three-dimensional ordered mesoporous (3DOM) CuCo₂O₄ materials have been synthesized via a hard template and used as bifunctional electrocatalysts for rechargeable Li-O₂ batteries. The characterization of the catalyst by X-ray diffractometry and transmission electron microscopy confirms the formation of a single-phase, 3-dimensional, ordered mesoporous CuCo₂O₄ structure. The as-prepared CuCo₂O₄ nanoparticles possess a high specific surface area of 97.1 m² g^{- 1} and a spinel crystalline structure. Cyclic voltammetry demonstrates that mesoporous CuCo₂O₄ catalyst enhances the kinetics for either oxygen reduction reaction (ORR) or oxygen evolution reaction (OER). The Li-O₂ battery utilizing 3DOM CuCo₂O₄ shows a higher specific capacity of 7456 mAh g^{- 1} than that with pure Ketjen black (KB). Moreover, the CuCo₂O₄-based electrode enables much enhanced cyclability with a 610 mV smaller discharge-recharge voltage gap than that of the carbon-only cathode at a current rate of 100 mA g^{- 1}. Such excellent catalytic performance of CuCo₂O₄ could be associated with its larger surface area and 3D ordered mesoporous structure. The excellent electrochemical performances coupled with its facile and cost-effective way will render the 3D mesoporous CuCo₂O₄ nanostructures as attractive electrode materials for promising application in Li-O₂ batteries.

Development of a multivariable online monitoring system for the thermoforming process

The thermoforming industry has been relatively slow to embrace modern measurement technologies. As a result researchers have struggled to develop accurate thermoforming simulations as some of the key aspects of the process remain poorly understood. For the first time, this work reports the development of a prototype multivariable instrumentation system for use in thermoforming. The system contains sensors for plug force, plug displacement, air pressure and temperature, plug temperature, and sheet temperature. Initially, it was developed to fit the tooling on a laboratory thermoforming machine, but later its performance was validated by installing it on a similar industrial tool. Throughout its development, providing access for the various sensors and their cabling was the most challenging task. In testing, all of the sensors performed well and the data collected has given a powerful insight into the operation of the process. In particular, it has shown that both the air and plug temperatures stabilize at more than 80C during the continuous thermoforming of amorphous polyethylene terephthalate (aPET) sheet at 110C. The work also highlighted significant differences in the timing and magnitude of the cavity pressures reached in the two thermoforming machines. The prototype system has considerable potential for further development. 

Towards optical polarization control of laser-driven proton acceleration in foils undergoing relativistic transparency

Control of the collective response of plasma particles to intense laser light is intrinsic to relativistic optics, the development of compact laser-driven particle and radiation sources, as well as investigations of some laboratory astrophysics phenomena. We recently demonstrated that a relativistic plasma aperture produced in an ultra-thin foil at the focus of intense laser radiation can induce diffraction, enabling polarization-based control of the collective motion of plasma electrons. Here we show that under these conditions the electron dynamics are mapped into the beam of protons accelerated via strong charge-separation-induced electrostatic fields. It is demonstrated experimentally and numerically via 3D particle-in-cell simulations that the degree of ellipticity of the laser polarization strongly influences the spatial-intensity distribution of the beam of multi-MeV protons. The influence on both sheath-accelerated and radiation pressure-accelerated protons is investigated. This approach opens up a potential new route to control laser-driven ion sources.

Global efficiency of innovative rotational mold directly heated by thermal fluid

The article is focused on analysis of global efficiency of new mold for rotational molding of plastic parts, being directly heated by thermal fluid. The overall efficiency is based on several items such as reduction of cycle time, better uniformity of heating-cooling and low energy consumption. The new tool takes advantage of additive fabrication and electroforming for making the optimal manifold and cavity shell of the mold. Experimental test of a prototype mold was carried out on an experimental rotational molding machine, developed for this purpose, measuring wall temperature, and internal air temperature, with and without plastic material inside. Results were compared with conventional mold heated into an oven and to theoretical simulations done by Computational Fluid Dynamic software (CFD). The analysis represents considerable improvement of cycle time related to conventional methods (heated by oven) and better thermal uniformity to conventional procedures by direct heating of oil with external channels. In addition to thermal analysis an energetic efficiency study was done. POLYM. ENG. SCI., 52:1998-2005, 2012. © 2012 Society of Plastics Engineers Copyright © 2012 Society of Plastics Engineers.

Internal cooling in rotational molding-A review

Rotational molding suffers from a relatively long cycle time, which hampers more widespread growth of the process. During each cycle, both the polymer and mold must be heated from room temperature to above polymer melting temperature and subsequently cooled to room temperature. The cooling time in this process is relatively long due to the poor thermal conductivity of plastics. Although rapid external cooling is possible, internal cooling rates are the major limitation. This causes the process to be uneconomical for large production runs of small parts. Various researchers have strived to minimize cycle times by applying various internal cooling procedures. This article presents a review of these methods, including computer simulations and practical investigations published to date. The effects of cooling rate on the morphology, shrinkage, warpage, and impact properties of rotationally molded polyolefins are also highlighted. In general, rapid and symmetrical cooling across the mold results in smaller spherulite size, increased mechanical properties and less potential warpage or distortion in moldings. POLYM. ENG. SCI., 2011. ©2011 Society of Plastics Engineers.

Interview with Dana L. Roth

An interview in four sessions, January and February 2014, with longtime Caltech chemistry librarian Dana L. Roth. Roth received his undergraduate education at Pasadena City College and UCLA (BS in chemistry, 1962). In 1965, he received master’s degrees in chemistry from Caltech and in library science from UCLA; that summer, he became Caltech’s chemistry librarian. After consolidation of Caltech’s division libraries in Millikan Library in 1967, he undertook various administrative responsibilities at Millikan over the years, along with his continuing duties as chemistry librarian. Active in the chemistry division of the Special Libraries Association. In 2008, inducted into the SLA Hall of Fame. That year he also received the Thomas W. Schmitt Staff Prize, presented to a Caltech staff member whose contributions “embody the values and spirit that enable the institute to achieve excellence in research and education.” Retired April 2013. In this interview he discusses his initial education as a chemist, including his graduate education at Caltech, and his switch to library science. He traces the development of library science in general and at Caltech—from the card-catalog days to the growth of the electronic Caltech Library system and the present state of online access and databases.

Illustrated guide to home chemistry experiments : all lab, no lecture.

Guía que explica cómo configurar y utilizar un laboratorio de química en casa con instrucciones, paso a paso, para la realización de experimentos en química básica. La primera parte de la publicación se dedica a describir lo esencial que se necesita para equipar, aprender a trabajar de forma segura y dominar las habilidades de un laboratorio. El resto del libro está compuesto por diecisiete capítulos que incluyen, la mayoría de ellos, varias sesiones de laboratorio cada una dedicada a un tema en particular. Las sesiones son adecuadas para un nivel medio o de primer año de curso de laboratorio de química.

A hand-book of industrial organic chemistry : adapted for the use of manufacturers, chemists, and all interested in the utilization of organic materials in the industrial arts /

Includes bibliographies.

A manual of chemistry on the basis of Dr. Turner's Elements of chemistry : containing in a condensed form all the most important facts and principles of the science : designed for a text book in colleges and other seminaries of learning /

Mode of access: Internet.

Preparation and characterization of chitosan-treated alginate microparticles incorporating all-trans retinoic acid

Chitosan treated alginate microparticles were prepared with the purpose of incorporating all-trans retinoic acid (ATRA) using an inexpensive, simple and fast method, enhancing dermal localization and sustaining the release of ATRA into the skin. Microparticles characterization, drug-polymer interaction, release profile and in vitro skin retention were investigated. Microparticles presented spherical shape and drug loading capacity of 47%. The drug content of these microparticles was affected by ATRA concentration and by the solvent used and it was more weakly affected by chitosan concentration. The release of ATRA was also affected by chitosan concentration. Microparticles prepared with 0.4% chitosan (w/w) resulted in drug release with a more sustained profile. The results of in vitro retention studies showed that chitosan treated alginate microparticles decreased the drug retention in the stratum corneum (SC), where occur the skin irritation, but maintained the ATRA concentration in the deeper skin layers, where occur the pathologies treated with ATRA. Then, the microparticles developed in this work can be a good candidate to improve the topical therapy with retinoid.

Using Computer-aided Drug Design and Medicinal Chemistry Strategies in the Fight Against Diabetes

The aim of this work is to present a simple, practical and efficient protocol for drug design, in particular Diabetes, which includes selection of the illness, good choice of a target as well as a bioactive ligand and then usage of various computer aided drug design and medicinal chemistry tools to design novel potential drug candidates in different diseases. We have selected the validated target dipeptidyl peptidase IV (DPP-IV), whose inhibition contributes to reduce glucose levels in type 2 diabetes patients. The most active inhibitor with complex X-ray structure reported was initially extracted from the BindingDB database. By using molecular modification strategies widely used in medicinal chemistry, besides current state-of-the-art tools in drug design (including flexible docking, virtual screening, molecular interaction fields, molecular dynamics. ADME and toxicity predictions), we have proposed 4 novel potential DPP-IV inhibitors with drug properties for Diabetes control, which have been supported and validated by all the computational tools used herewith.

The chemistry of copper patination

The chemistry of copper patination was investigated by two series of experiments. The chemistry of an aqueous copper-sulphate solution was studied at concentrations and pH values near those predicted in an electrolyte on copper exposed to the atmosphere. The electrochemical reactions in an electrolyte in contact with cuprite were investigated in a reaction vessel which used cuprite powder in artificial rainwater to study the electrochemistry of the atmospheric corrosion and patination of copper. Typical sulphate concentrations in rainwater are sufficient to precipitate posnjakite (Cu4SO4(OH)(6)2H(2)O)), a possible precursor to brochantite, within an hour of wetting a cuprite surface. Brochantite (Cu4SO4(OH)(6)), the most commonly found copper salt in natural patinas is responsible for their green appearance. Precipitation of brochantite from the electrolyte resulted from an increase in pH due to the cathodic reduction of oxygen and an increase in cupric ion concentrations by cuprite oxidation. (C) 1998 Elsevier Science Ltd. All rights reserved.