Thermoplastic blend demixing by a high‐pressure,high‐temperature process

The analysis of a thermoplastic polymer blend requires a precise separation of the blend components, which is usually performed by selective solvent extraction. However, when the components are high‐molecular‐weight polymers, a complete separation is very difficult. The use of fluids in near critical and supercritical conditions becomes a promising alternative to reach a much more precise separation. In this work, a method to separate reactive and physical blends from high‐molecular‐weight commercial polymers is proposed. Polyethylene (PE)/polystyrene (PS) blends were separated into their components with n‐propane, n‐pentane, and n‐heptane at near critical and supercritical conditions. The selectivity of each solvent was experimentally studied over a wide range of temperatures for assessing the processing windows for the separation of pure components. The entire PE phase was solubilized by n‐pentane and n‐heptane at similar temperatures, whereas propane at supercritical conditions could not dissolve the fraction of high‐molecular‐weight PE. The influence of the blend morphology and composition on the efficiency of the polymer separation was studied. In reactive blends, the in situ copolymer formed was solubilized with the PE phase by chemical affinity. The method proposed for blend separation is easy, rapid, and selective and seems to be a promising tool for blend separation, particularly for reactive blends, for which the isolation of the copolymer is essential for characterization © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2361–2369, 2005     

Shapeable matrix‐free Spectra® fiber‐reinforced polymeric composites via high‐temperature high‐pressure sintering: Process‐structure‐property relationship

In an exploratory effort to find a new way to make high‐performance composites used in ballistic protective applications, matrix‐free Spectra® fiber‐reinforced polymeric composites are produced via a novel processing method called high‐temperature high‐pressure sintering. Mechanical testing at ambient and elevated temperatures proves that the fibers can maintain their properties after processing. The characteristics and properties of the final products vary with different processing conditions. Their microstructure and morphology were investigated using SEM and WAXD. Their mechanical properties, including interlayer adhesion, rigidity, and ballistic performance, were measured and compared with those of the conventional composites. The sintering mechanism is proposed and verified. Spectra cloth is capable of being shaped to produce complex double curvatures by a thermoforming process, using a simple hemispherical mold. Success in different molding sequences and procedures shows the versatility in manufacturing. The theoretical background for the thermoformability is explained in terms of molecular interaction, microstructure, and morphology. Selective thermomechanical properties of the molded structures were measured. By combining the knowledge and information from the aforementioned studies, the process‐structure‐property relationship is established, which gives in‐depth and better understanding of this unique high‐temperature high‐pressure sintering process for consolidating Spectra cloth. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2767–2789, 2005     

VinaMPI: Facilitating multiple receptor high‐throughput virtual docking on high‐performance computers

The program VinaMPI has been developed to enable massively large virtual drug screens on leadership‐class computing resources, using a large number of cores to decrease the time‐to‐completion of the screen. VinaMPI is a massively parallel Message Passing Interface (MPI) program based on the multithreaded virtual docking program AutodockVina, and is used to distribute tasks while multithreading is used to speed‐up individual docking tasks. VinaMPI uses a distribution scheme in which tasks are evenly distributed to the workers based on the complexity of each task, as defined by the number of rotatable bonds in each chemical compound investigated. VinaMPI efficiently handles multiple proteins in a ligand screen, allowing for high‐throughput inverse docking that presents new opportunities for improving the efficiency of the drug discovery pipeline. VinaMPI successfully ran on 84,672 cores with a continual decrease in job completion time with increasing core count. The ratio of the number of tasks in a screening to the number of workers should be at least around 100 in order to have a good load balance and an optimal job completion time. The code is freely available and downloadable. Instructions for downloading and using the code are provided in the Supporting Information. © 2013 Wiley Periodicals, Inc.     

Ultra‐high‐pressure‐assisted extraction of wedelolactone and isodemethylwedelolactone from Ecliptae Herba and purification by high‐speed counter‐current chromatography

Ultra‐high‐pressure extraction combined with high‐speed counter‐current chromatography was employed to extract and purify wedelolactone and isodemethylwedelolactone from Ecliptae Herba. The operating conditions of ultra‐high‐pressure extraction were optimized using an orthogonal experimental design. The optimal conditions were 80% aqueous methanol solvent, 200 MPa pressure, 3 min extraction time and 1:20 (g/mL) solid–liquid ratio for extraction of wedelolactone and isodemethylwedelolactone. After extraction by ultra‐high pressure, the extraction solution was concentrated and subsequently extracted with ethyl acetate; a total of 2.1 g of crude sample was obtained from 100 g of Ecliptae Herba. A two‐phase solvent system composed of petroleum ether–ethyl acetate–methanol–water (3:7:5:5, v/v) was used for high‐speed counter‐current chromatography separation, by which 23.5 mg wedelolactone, 6.8 mg isodemethylwedelolactone and 5.5 mg luteolin with purities >95% were purified from 300 mg crude sample in a one‐step separation. This research demonstrated that ultra‐high‐pressure extraction combined with high‐speed counter‐current chromatography was an efficient technique for the extraction and purification of coumestans from plant material.     

Multiple‐injection high‐throughput gas chromatography analysis

Multiple‐injection techniques have been shown to be a simple way to perform high‐throughput analysis where the entire experiment resides in a single chromatogram, simplifying the data analysis and interpretation. In this study, multiple‐injection techniques are applied to gas chromatography with flame ionization detection and mass detection to significantly increase sample throughput. The unique issues of implementing a traditional “Fast” injection mode of multiple‐injection techniques with gas chromatography and mass spectrometry are discussed. Stacked injections are also discussed as means to increase the throughput of longer methods where mass detection is unable to distinguish between analytes of the same mass and longer retentions are required to resolve components of interest. Multiple‐injection techniques are shown to increase instrument throughput by up to 70% and to simplify data analysis, allowing hits in multiple parallel experiments to be identified easily.     

Monitoring phase transition of aqueous biomass model substrates by high‐pressure and high‐temperature microfluidics

Aqueous‐Phase Reforming (APR) is a promising hydrogen production method, where biomass is catalytically reformed under high pressure and high temperature reaction conditions. To eventually study APR, in this paper, we report a high‐pressure and high‐temperature microfluidic platform that can withstand temperatures up to 200°C and pressures up to 30 bar. As a first step, we studied the phase transition of four typical APR biomass model solutions, consisting of 10 wt% of ethylene glycol, glycerol, xylose or xylitol in MilliQ water. After calibration of the set‐up using pure MilliQ water, a small increase in boiling point was observed for the ethylene glycol, xylitol and xylose solutions compared to pure water. Phase transition occurred through either explosive or nucleate boiling mechanisms, which was monitored in real‐time in our microfluidic device. In case of nucleate boiling, the nucleation site could be controlled by exploiting the pressure drop along the microfluidic channel. Depending on the void fraction, various multiphase flow patterns were observed simultaneously. Altogether, this study will not only help to distinguish between bubbles resulting from a phase transition and/or APR product formation, but is also important from a heat and mass transport perspective.     

Gas‐free initiators for high‐temperature free‐radical polymerization

Quaternary ammonium persulfates as free‐radical initiators for high‐temperature polymerization are synthesized and their shelf‐life stability investigated. These initiators do not have gaseous byproducts and are therefore ideal for frontal polymerization, a process in which polymeric materials are produced via a thermal front that propagates through the unreacted monomer/initiator solution. Quaternary ammonium persulfate initiators offer additional qualities such as high solubility in organic media and low volatility, which are desirable for frontal polymerization. The initiators are synthesized using two procedures, and the initiating efficacy of the respective products is compared to a peroxide initiator in the frontal polymerization of 1,6‐hexanediol diacrylate. Of all the quartenary ammonium persulfates synthesized, tricaprylmethylammonium (Aliquat) persulfate (APSO) is the best initiator for frontal polymerization because it is soluble in organic media, is very reactive, and does not produce volatile byproducts under decomposition. A study of the decomposition kinetics of APSO is performed, and frontal polymerization is proposed as a quicker analytical technique to assay the purity. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3984–3990, 2000     

Bio‐based high‐performance waterborne hyperbranched polyurethane thermoset

Tannic‐acid‐based low volatile organic compound‐containing waterborne hyperbranched polyurethane was prepared. In order to improve the performance, it was modified in an aqueous medium using a glycerol‐based hyperbranched epoxy and vegetable‐oil‐based poly(amido amine) at different wt%. The combined system was cross‐linked by heating at 100°C for 45 min. Fourier transform infrared spectroscopy and swelling study were used to confirm the curing. A dose‐dependent improvement of properties was witnessed for the thermoset. Thermoset with 30 wt% epoxy showed excellent improvements in mechanical properties like tensile strength (~3.4 fold), scratch hardness (~2 fold), impact resistance (~1.3 fold), and toughness (~1.7 fold). Thermogravimetric analysis revealed enhancement of thermal properties (maximum 70°C increment of degradation temperature and 8°C increment of T_g). The modified system showed better chemical and water resistance compared with the neat polyurethane. Biodegradation study was carried out by broth culture method using Pseudomonas aeruginosa as the test organism. An adequate biodegradation was witnessed, as evidenced by weight loss profile, bacterial growth curve, and scanning electron microscope images. The work showed the way to develop environmentally benign waterborne polyurethane as a high‐performance material by incorporating a reactive modifier into the polymer network. Use of benign solvent and bio‐based materials as well as profound biodegradability justified eco‐friendliness and sustainability of the modified system. Copyright © 2015 John Wiley & Sons, Ltd.     

Rating high‐throughput screening results via h‐index

The quantification of both the impact and quality of a scientist's publication record is an essential step in making decisions concerning hiring, promotion, and allocation of funding. In an attempt to resolve this problem, Hirsh proposed the “h‐index,” a single‐number criterion incorporating both the number of publications and the number of citations per publication. This value facilitates rating of a scientist's performance and is now one of the most commonly used matrices. Here, we would like to propose the rating of high‐throughput screening (HTS) result by the h‐index. Rating HTS result is to estimate how the HTS result is preferred by a medicinal chemist. In this study, we applied the h‐index for rating HTS results and observed an enhanced rating of preferred starting points for drug development. In addition, we developed a new index, the maximum common structure (MCS) index, which is more effective than the h‐index. Copyright © 2014 John Wiley & Sons, Ltd.     

Fast and sensitive analysis of beta blockers by ultra‐high‐performance liquid chromatography coupled with ultra‐high‐resolution TOF mass spectrometry

This paper presents a method for the determination of acebutolol, betaxolol, bisoprolol, metoprolol, nebivolol and sotalol in human serum by liquid–liquid extraction and ultra‐high‐performance liquid chromatography coupled with ultra‐high‐resolution TOF mass spectrometry. After liquid–liquid extraction, beta blockers were separated on a reverse‐phase analytical column (Acclaim RS 120; 100 × 2.1 mm, 2.2 μm). The total run time was 6 min for each sample. Linearity, limit of detection, limit of quantification, matrix effects, specificity, precision, accuracy, recovery and sample stability were evaluated. The method was successfully applied to the therapeutic drug monitoring of 108 patients with hypertension. This method was also used for determination of beta blockers in 33 intoxicated patients.     

Silole‐containing polymers for high‐efficiency polymer solar cells

Silole‐containing conjugated polymers ( P1 and P2 ) carrying methyl and octyl substituents, respectively, on the silicon atom were synthesized by Suzuki polycondensation. They show strong absorption in the region of 300–700 nm with a band gap of about 1.9 eV. The two silole‐containing conjugated polymers were used to fabricate polymer solar cells by blending with PC₆₁BM and PC₇₁BM as the active layer. The best performance of photovoltaic devices based on P1 /PC₇₁BM active layer exhibited power conversion efficiency (PCE) of 2.72%, whereas that of the photovoltaic cells fabricated with P2 /PC₇₁BM exhibited PCE of 5.08%. 1,8‐Diiodooctane was used as an additive to adjust the morphology of the active layer during the device optimization. PCE of devices based on P2 /PC₇₁BM was further improved to 6.05% when a TiO_x layer was used as a hole‐blocking layer. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

The high‐temperature tribological properties of Si‐DLC films

The tribological properties of Silicon‐containing diamond‐like‐carbon (Si‐DLC) films, deposited by magnetron sputtering Si target in methane/argon atmosphere, were studied in comparison with diamond‐like‐carbon (DLC) films. The DLC films disappeared because of the oxidation in the air at 500 °C, whereas the Si‐DLC films still remained, implying that the addition of Si improved significantly the thermal stability of DLC films. Retarded hydrogen release from DLC film at high temperature and silicon oxide on the surface might have contributed to lower friction coefficient of the Si‐DLC films both after annealing treatment and in situ high‐temperature environment. Copyright © 2012 John Wiley & Sons, Ltd.     

Immersion film‐forming compositions based on high‐molecular polyvinylpyrrolidone

This work presents the results of experimental study of new immersion‐coating compositions based on high‐molecular polyvinylpyrrolidone and different inorganic additions. The formation of transparent polymer coating on the surface of tested optical element is new approach for visual control of optical materials. The film‐forming immersion compositions can be considered as the new and perspective field of the practical application of polymer materials. Copyright © 2016 John Wiley & Sons, Ltd.     

Benzylisoquinoline alkaloid analysis using high‐resolution Orbitrap LC‐MSn

Benzylisoquinoline alkaloids (BIAs) have profound implications on human health owing to their potent pharmacological properties. Notable naturally occurring BIAs are the narcotic analgesics morphine, the cough suppressant codeine, the potential anticancer drug noscapine, the muscle relaxant papaverine, and the antimicrobial sanguinarine, all of which are produced in opium poppy (Papaver somniferum). Thebaine, an intermediate in the biosynthesis of codeine and morphine, is used in the manufacture of semisynthetic opiates, including oxycodone and naloxone. As the only commercial source of pharmaceutical opiates, opium poppy has been the focus of considerable research to understand BIA metabolism in the plant. The elucidation of several BIA biosynthetic pathways has enabled the development of synthetic biology platforms aimed at the alternative commercial production of valuable phytochemicals in microorganisms. The detection and identification of BIA pathway products and intermediates in complex extracts is essential for the continuing advancement of research in plant specialized metabolism and microbial synthetic biology. Herein, we report the use of liquid chromatography coupled with linear trap quadrupole and high‐resolution Orbitrap multistage mass spectrometry to characterize 44 authentic BIAs using collision‐induced dissociation (CID), higher‐energy collisional dissociation (HCD), and pulsed Q collision‐induced dissociation (PQD) MS² fragmentation, with MS² CID followed by MS³ and MS⁴ fragmentation. Our deep library of diagnostic spectral data constitutes a valuable resource for BIAs identification. In addition, we identified 22 BIAs in opium poppy latex and roots extracts.     

Round‐robin experiment in high‐temperature gel permeation chromatography

The results of an interlaboratory or round‐robin experiment in high‐temperature gel permeation chromatography (HT‐GPC) analysis are presented. The intention was to determine and raise awareness of interlaboratory reproducibility of HT‐GPC techniques. Fifteen laboratories performed analyses of five polyethylene samples and standards SRM 1475 and 1476. Reproducibility, as measured by the interlaboratory standard deviation (s_LAB), was greatly influenced by the breadth of the molecular weight distribution (MWD) and branching. The s_LAB values for the weight‐average molecular weight (M_w) of linear polyethylenes of narrow and broad MWDs were 4 and 14%, respectively. For branched polymers, GPC viscometry methods are shown to measure significantly higher molecular weights than the noncoupled GPC method, with higher variance. For branched polyethylenes measured with GPC viscometry, the reproducibility of M_w was characterized by s_LAB = 18%. Reproducibility of the SRM 1475 standard was better than for unknowns. The results for branched standard SRM 1476 emphasize the important role of the detection method in GPC but call into question the use of this material as a molecular weight standard. For single‐site polyethylene, only a handful of labs measured an MWD that closely matched the Flory distribution. Qualitatively, the responses indicate that many variations in instrument and analytical methods exist among laboratories; this is partly a reflection of the development and refinements that this technique must yet undergo before a truly standard method is widely accepted and practiced. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 905–921, 2002     

Mechanical properties of high‐density polyethylene and crosslinked high‐density polyethylene in crude oil and its components

The tensile and stress‐relaxation properties of an uncrosslinked and a loosely silane‐crosslinked high‐density polyethylene exposed to organic “crude‐oil” penetrants were assessed. The measurements were performed on penetrant‐saturated samples, surrounded by the organic liquid throughout the experiment. The penetrant solubilities in the two polymers were similar and in accordance with predicted values based on the solubility parameter method. The stiffness and strength of the swollen samples were significantly less than those of the dry samples, indicating a plasticization of the amorphous component. Raman spectroscopy on polyethylene exposed to deuterated n‐hexane revealed a penetrant‐induced partial melting/dissolution of the crystal surface and an intact crystal core component. The stress‐relaxation rates, within the time frame of the experiment (～1 s to 18 h), were approximately the same, independent of silane‐crosslinks and the presence of penetrants. This indicated that the mechanical α‐relaxation, which is the main relaxation process occurring in the measured time interval, was not affected by the penetrants. Consequently, its rate seemed to be independent of the crystal surface dissolution (decrease in the content of crystal‐core interface). The shape of the “log stress–log time” curves of the swollen samples was, however, different from that of the dry samples. This was most likely attributed to a time‐dependent saturation of penetrant to a higher level associated with the stretched state of the polymer sample. The silane crosslinks affected only the elongation at break, which was less than that of the uncrosslinked material. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 641–648, 2006     

An expedient reverse‐phase high‐performance chromatography (RP‐HPLC) based method for high‐throughput analysis of deferoxamine and ferrioxamine in urine

The present study was planned to optimize and validate an expedient reverse‐phase high chromatography (RP‐HPLC) based protocol for the analysis of deferoxamine (DFO) and ferrioxamine (FO) in urinary execration of patients suffering β ‐thalassemia major. The optimized RP‐HPLC method was found to be linear over the wide range of DFO and FO concentration (1–90 μg/mL) with appreciable recovery rates (79.64–97.30%) of quality controls at improved detection and quantitation limits and acceptable inter and intraday variability. Real‐time analysis of DFO and FO in the urine of thalassemic patients (male and female) at different intervals of Desferal®(Novartis Pharmaceuticals Corporation) injection revealed DFO and FO excretion at significantly (p < 0) different rates. The maximum concentrations of DFO (76.7 ± 3.06 μg/mL) and FO (74.2 ± 3.25 μg/mL) were found in urine samples, collected after 6 h of drug infusion while the minimum levels of DFO (1.10 ± 0.12 μg/mL) and FO (2.97 ± 0.13 μg/mL) were excreted by patients after 24 h. The present paper offers balanced conditions for an expedient, reliable and quick determination of DFO and FO in urine samples.