Computational study of the dissolution of cellulose into single chains: the role of the solvent and agitation

Cellulose - We investigate the dissolution mechanism of cellulose using molecular dynamics simulations in both water and a mixture solvent consisting of water with Na $$^+$$ , OH $$^-$$...     

Load balancing by work–stealing in quantum chemistry calculations: Application to hybrid density functional methods

Parallel implementations of quantum chemistry programs targeting supercomputers are challenging applications of dynamic load balancing algorithms. The implementation of work stealing (WS) algorithms is discussed and their usefulness is demonstrated. Evaluation of the four‐center integrals of a Cu₁₀ cluster requires 25 core‐hours overall, achieving 88% efficiency with simple WS for 2048 cores, and 97% with task presorting based on a cost estimate. Limitations of cost sorting become noticeable for larger systems. When spatial symmetry is exploited together with integral screening, bundling the original tasks yields an efficiency of 98% for Cu₇₉ in O_h symmetry on 512, 1204, and 2048 cores. The advantage of WS algorithms described in this work is not limited to the evaluation of four‐center integrals. © 2014 Wiley Periodicals, Inc.     

Pulsed DC magnetron sputtering of transparent conductive oxide layers

A comprehensive material study of different transparent conductive oxides （TCOs） is presented. The layers are deposited by pulsed direct current （DC） magnetron sputtering in an inline sputtering system. Indium tin oxide （ITO） films are studied in detail. The optimum pressure of 0.33 Pa （15Ar：202） produces a 300- nm thin film with a specific resistivity p of 2.2 × 10-6 Ωm and a visual transmittance of 81%. Alternatively, ZnO：A1 and ZnO：Ga layers with thicknesses of 200 and 250 nm are deposited with a minimum resistivity of 5.5× 10-6 and 6.8× 10-6Ωm, respectively. To compare the optical properties in the ultraviolet （UV） range, the optical spectra are modeled and the band gap is determined.     

Molecular electrocatalysis at soft interfaces

The fundamental aspects of electrochemistry at liquid-liquid interfaces are introduced to present the concept of molecular electrocatalysis. Here, a molecular catalyst is adsorbed at the interface to promote a proton coupled electron transfer reaction such as hydrogen evolution or oxygen reduction using lipophilic electron donors.     

Catalytic Functionalization of Indoles in a New Dimension

140 Years ago Adolf von Baeyer proposed the structure of a heteroaromatic compound which revolutionized organic and medical chemistry: indole. After more than a century, indole itself and the complexity of naturally occurring indole derivatives continue to inspire and influence developments in synthetic chemistry. In particular, the ubiquitous presence of indole rings in pharmaceuticals, agrochemicals, and functional materials are testament to the ever increasing interest in the design of mild and efficient synthetic routes to functionalized indole derivatives. This Review emphasizes the achievements in the selective catalytic functionalization of indoles (C? C bond‐forming processes) over the last four years.     

Electromembrane extraction of basic drugs from untreated human plasma and whole blood under physiological pH conditions

The present work describes the first systematic study of electromembrane extraction (EME) from biological matrices under physiological conditions. Six basic drugs with protein binding in the range of 20–97% were extracted from untreated human plasma and whole blood through a supported liquid membrane (SLM) consisting of 1-ethyl-2-nitrobenzene impregnated in the walls of a hollow fiber, and into an acidified aqueous solution inside the lumen of the fiber. The electrical potential difference over the membrane reduced the protein binding of the drugs and transported the free drug fraction over the membrane. Recoveries in the range 25–65% were obtained with 10-min extraction time and an applied voltage of only 10 V over the SLM. Interday precision better than 20% RSD and linearity in the range 0.5–10 μg/mL were obtained for nortriptyline and methadone. Extraction from untreated whole blood was also demonstrated with recoveries in the range 19–51%.     

A new proof of Ramanujan’s modular equation relating R(q) with R(q 5)

We give a new proof of Ramanujan’s modular identity relating R(q) with R(q ⁵), where R(q) is the famous Rogers–Ramanujan continued fraction. Our formulation is stronger than those of preceding authors; in particular, we give for the first time identities for the expressions appearing in the numerator and the denominator of Ramanujan’s identity. A related identity for R(q) that has partition-theoretic connections is also proved.     

Two modular equations for squares of the Rogers–Ramanujan functions with applications

Two modular identities of Gordon, McIntosh, and Robins are shown to be connected to the Rogers–Ramanujan continued fraction R(q), and in particular to Ramanujan’s parameter k:=R(q)R ²(q ²). Using this connection, we give new modular relations for R(q), and offer new and uniform proofs of several results of Ramanujan. In particular, we give a new proof of a famous and fundamental modular identity satisfied by the Rogers–Ramanujan continued fraction. We furthermore show that many analogous results hold for Ramanujan’s parameters μ:=R(q)R(q ⁴) and ν:=R ²(q ^1/2)R(q)/R(q ²). New proofs are offered for modular relations connecting R(q) to R(−q), R(q ²), and R(q ⁴), and new relations connecting R(q) at these arguments are offered. Eleven identities for the Rogers–Ramanujan functions are proved, including four new identities.      

Electrokinetic migration across artificial liquid membranes Tuning the membrane chemistry to different types of drug substances

Twenty different basic drugs were electrokinetically extracted across a thin artificial organic liquid membrane with a 300 V d.c. electrical potential difference as the driving force. From a 300 microl aqueous sample (acidified corresponding to 10mM HCl), the drugs were extracted for 5 min through a 200 microm artificial liquid membrane of a water immiscible organic solvent immobilized in the pores of a polypropylene hollow fiber, and into a 30 microl aqueous acceptor solution of 10mM HCl inside the lumen of the hollow fiber. Hydrophobic basic drugs (logP>1.7) were effectively isolated utilizing 2-nitrophenyl octyl ether (NPOE) as the artificial liquid membrane, with recoveries up to 83%. For more hydrophilic basic drugs (logP<1.0), a mixture of NPOE and 25% (w/w) di-(2-ethylhexyl) phosphate (DEHP) was required to ensure efficient extraction, resulting in recoveries up to 75%. DEHP was expected to act as an ion-pair reagent ion-pairing the protonated hydrophilic drugs at the interface between the sample and the membrane, resulting in permeation of the interface.