bluuebunny/crossref_metadata_2025 huggingface dataset:
2,3‐Pentanedione – Method for the determination of 2,3‐pentanedione in workplace air using gas chromatography‐mass spectrometry (GC‐MS) [Air Monitoring Methods, 2017]
Authors: Schuh C. , Nitschke L. , Hebisch R. , Brock T.H. , Hartwig A. ,   MAK Commission
Published: July 2018

This analytical method is a validated measurement procedure for the determination of 2,3‐pentanedione in workplace air in a concentration range of a tenth up to twice the currently valid MAK value of 0,083 mg/m
3
. Sampling is performed by drawing a defined volume of air through a silica gel tube using a suitable flow‐regulated pump. The flow rate is set to 0.33 L/min with a recommended air sample volume of approx. 20 L at a sampling time of 1 hour. For sampling 1 hour or 15 min (checking the short‐term value) can be used. The collected 2,3‐pentanedione is desorbed with acetone containing the internal standard cyclohexanone and then analysed by means of gas chromatography‐mass spectrometry (GC‐MS). The quantitative evaluation is based on a calibration function obtained by means of a 10‐point calibration using cyclohexanone as internal standard. The limit of quantification is 0.0025 mg/m
3
based on an air sample volume of approx. 20 L or 0.010 mg/m
3
based on an air sample volume of approx. 5 L (for short‐term value).

Joint Publication of the Analytical Subcommittee of the Chemistry Board of Experts of the Expert Committee Raw Materials and Chemical Industry of the German Social Accident Insurance and the working group “Air Analyses” of the Permanent Senate Commission of the DFG for the Investigation of Health Hazards of Chemical Compounds in the Work Area.
Addendum to Ethylbenzene [BAT Value Documentation, 2016]
Authors: Reuter U. , Göen T. , Drexler H. , Hartwig A. ,   MAK Commission
Published: July 2018

In 2015 the German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has re‐evaluated the biological tolerance value at the work place (BAT value) and the exposure equivalents for carcinogenic substances (EKA) for ethylbenzene [CAS No.
100‐41‐4
], considering mandelic acid and phenylglyoxylic acid in urine as well as 2‐ and 4‐ethylphenol in urine (after hydrolysis) to characterise the internal exposure. Ethylbenzene was classified in category 4 for carcinogenic substances. It can easily pass through the skin, so biological monitoring is necessary for a valid individual risk assessment.

The BAT value for styrene, which also considers the sum of mandelic acid and phenylglyoxylic acid, was evaluated as creatinine related value. For practical reasons, the BAT value and the EKA for ethylbenzene are transformed into creatinine related values as well. Therefore, volume‐related results of studies were re‐calculated using a conversion factor of 1.2 g creatinine/l urine. The available studies are in good accordance. A BAT value for the sum of mandelic acids plus phenylglyoxylic acid of 250 mg/g creatinine was evaluated. Sampling should be performed at the end of exposure or end of shift.

For the EKA correlation, the values for the parameter mandelic acid plus phenylglyoxylic acid were also re‐calculated using a conversion factor of 1.2 g creatinine/l urine. Sampling time is at the end of exposure or end of shift. For the parameter 2‐plus 4‐ethylphenol, data differ in the two available older studies. While in one study only 2‐ethylphenol was found as metabolite of ethylbenzene, in the other study only 4‐ethylphenol was determined. In a more recent study, solely 4‐ethylphenol, but no 2‐ethylphenol could be analysed. Because of the inconsistency of the data, the EKA for the parameter 2‐ plus 4‐ethylphenol is withdrawn.
Addendum zu Toluol [BAT Value Documentation in German language, 2018]
Authors: Jäger T. , Drexler H. , Hartwig A. ,   MAK Commission
Published: July 2018

In 2017, the German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has derived a BAT value (“Biologischer Arbeitsstoff‐Toleranzwert”) for toluene [CAS NO.
108‐88‐3
] in urine to characterize the internal exposure at the workplace. Available publications are described in detail.

The evaluation of the BAT value was based on the relationship between toluene uptake by inhalation at the MAK value and the corresponding urinary excretion rate of unmetabolized toluene. An eight‐hour exposure to the present MAK value of 190 mg toluene/m
3
correlated with a mean urinary toluene concentration of approximately 75 µg/l. Therefore, a BAT value of 75 µg toluene/l urine was evaluated. Sampling time is at the end of exposure or the end of the working shift.
Neonicotinoide mit 6‐Chlorpyridinyl‐Gruppe (z. B. Imidacloprid, Acetamiprid, Thiacloprid, Nitenpyram, Boscalid) – Bestimmung von 6‐Chlornikotinsäure in Urin mittels GC‐MS [Biomonitoring Methods in German language, 2018]
Authors: Gries W. , Leng G. , Hoppe H.‐W. , Göen T. , Hartwig A. ,   MAK Commission
Published: July 2018

The working group „Analyses in Biological Materials“ of the Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area verified the presented biomonitoring method.

Neonicotinoids with a 6‐chloropyridinyl structure are metabolised in warm‐blooded organisms to 6‐chloronicotinic acid that is excreted in urine. This analytical method permits the specific quantification of 6‐chloronicotinic acid in urine. For determination, 2 mL of a urine sample are hydrolysed using 500 µL concentrated hydrochloric acid to cleave the conjugates, which are subsequently extracted with methyl tert‐butyl ether. The solvent is evaporated to dryness under a stream of nitrogen and the residue is dissolved in acetonitrile. Then 6‐chloronicotinic acid is derivatised with hexafluoroisopropanol (HFIP) in the presence of diisopropylcarbodiimide. In a subsequent washing and extraction step, the formed HFIP ester is extracted using isooctane and an aliquot is injected in the GC‐MS system for quantitative analysis. Calibration is performed using calibration standards that are prepared in pooled urine and processed in the same way as the samples to be analysed.

The method was extensively validated and the reliability data were confirmed by an independent laboratory, which has established and cross‐checked the whole procedure.
Bis(morpholino)methan [MAK Value Documentation in German language, 2018]
Authors: Hartwig A. ,   MAK Commission
Published: July 2018

The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has re‐evaluated 4,4′‐methylenedimorpholine [5625‐90‐1], considering all toxicological endpoints. Available publications and unpublished study reports are described in detail. 4,4′‐Methylenedimorpholine is a formaldehyde releaser. The substance is corrosive to rabbit skin and induces local effects in the forestomach of rats after prolonged oral application. Therefore, the critical effect is presumably the local irritation in the respiration tract. Adequate data in humans and inhalation studies in animals to derive a maximum concentration at the work place (MAK value) is not available. Thus, the assignment of the substance to Section II b of the List of MAK and BAT Values is retained. A prenatal toxicity study in rabbits does not show any developmental toxicity up to the highest dose tested of 100 mg/kg body weight and day. 4,4′‐Methylenedimorpholine induces mutations in bacteria and is mutagenic and predominantly clastogenic to mammalian cells. The clastogenicity has, however, not been confirmed in vivo. Adequate carcinogenicity studies with 4,4′‐methylenedimorpholine are not available but the release of the local carcinogen formaldehyde has also to be taken into account for evaluating the carcinogenicity of 4,4′‐methylenedimorpholine. At work places where 4,4′‐methylenedimorpholine is used the mean air concentration of formaldehyde is about 2 µl/m3. As the difference between the MAK value of formaldehyde of 300 µl/m3and the work place air concentration is sufficiently large, and the measured concentrations are in the range of the background levels, no classification into a Carcinogen Category is confirmed. Clinical data in humans reveal a skin sensitizing potential which is also due to the release of formaldehyde. The results of the animal experiments are negative but they are carried out at very low concentrations. 4,4′‐Methylenedimorpholine is designated with an “Sh” notation. Skin contact is not expected to contribute significantly to systemic toxicity.
Propylenglykoldinitrat [MAK Value Documentation in German language, 2018]
Authors: Hartwig A. ,   MAK Commission
Published: July 2018

The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has re‐evaluated the maximum concentration at the workplace (MAK value) of propylene glycol dinitrate [
6423‐43‐4
], considering all toxicological endpoints. A detailed description of the underlying studies is given.

The critical effect in volunteers after an 8‐hour exposure to 0.1 ml/m
3
of propylene glycol dinitrate was vasodilation, as indicated by the development of headaches. The effects were very slight. After 4‐hour exposure to 0.2  ml/m
3
most of the volunteers developed headaches and changes in visual evoked responses. At 0.03 ml/m
3
no effects were observed. In occupational situations it is difficult to assess the levels of exposure to propylene glycol dinitrate that induce symptoms and effects, because of both respiratory tract and skin absorption of vapours. The MAK value for propylene glycol dinitrate has been lowered to 0.01 ml/m
3
by analogy with nitroglycerin and ethylene glycol dinitrate because of the same mode of action and the similar NOAEC and LOAEC.

The MAK value also applies to the sum of the concentrations of the three nitrate esters nitroglycerin, ethylene glycol dinitrate and propylene glycol dinitrate in the air. As systemic effects are critical, the assignment to Peak Limitation Category II and the excursion factor of 1, due to the short half‐life, are retained. Although there are no studies on developmental toxicity, propylene glycol dinitrate is assigned to Pregnancy Risk Group C by analogy with nitroglycerin and ethylene glycol dinitrate. No data are available for genotoxicity or carcinogenicity. Skin contact may contribute significantly to systemic toxicity and propylene glycol dinitrate continues to be designated with an “H”. Sensitization is not expected from the limited data.
Production of patient‐specific electron beam aperture cut‐outs using a low‐cost, multi‐purpose 3D printer
Authors: Michiels Steven , Mangelschots Bram , Roover Robin De , Devroye Cédric , Depuydt Tom
Published: July 2018

Electron beam collimators for non‐standard field sizes and shapes are typically fabricated using Styrofoam molds to cast the aperture cut‐out. These molds are often produced using a dedicated foam cutter, which may be expensive and only serves a single purpose. An increasing number of radiotherapy departments, however, has a 3D printer on‐site, to create a wide range of custom‐made treatment auxiliaries, such as bolus and dosimetry phantoms. The 3D printer can also be used to produce patient‐specific aperture cut‐outs, as elaborated in this note. Open‐source programming language was used to automatically generate the mold's shape in a generic digital file format readable by 3D printer software. The geometric mold model has the patient's identification number integrated and is to be mounted on a uniquely fitting, reusable positioning device, which can be 3D printed as well. This assembly likewise fits uniquely onto the applicator tray, ensuring correct and error‐free alignment of the mold during casting of the aperture. For dosimetric verification, two aperture cut‐outs were cast, one using a conventionally cut Styrofoam mold and one using a 3D printed mold. Using these cut‐outs, the clinical plan was delivered onto a phantom, for which the transversal dose distributions were measured at 2 cm depth using radiochromic film and compared using gamma‐index analysis. An agreement score of 99.9% between the measured 2D dose distributions was found in the (10%–80%) dose region, using 1% (local) dose‐difference and 1.0 mm distance‐to‐agreement acceptance criteria. The workflow using 3D printing has been clinically implemented and is in routine use at the author's institute for all patient‐specific electron beam aperture cut‐outs. It allows for a standardized, cost‐effective, and operator‐friendly workflow without the need for dedicated equipment. In addition, it offers possibilities to increase safety and quality of the process including patient identification and methods for accurate mold alignment.
Advanced Porous Materials in Mixed Matrix Membranes
Authors: Cheng Youdong , Ying Yunpan , Japip Susilo , Jiang Shu‐Dong , Chung Tai‐Shung , Zhang Sui , Zhao Dan
Published: July 2018

Membrane technology has gained great interest in industrial separation processing over the past few decades owing to its high energy efficiency, small capital investment, environmentally benign characteristics, and the continuous operation process. Among various types of membranes, mixed matrix membranes (MMMs) combining the merits of the polymer matrix and inorganic/organic fillers have been extensively investigated. With the rapid development of chemistry and materials science, recent studies have shifted toward the design and application of advanced porous materials as promising fillers to boost the separation performance of MMMs. Here, first a comprehensive overview is provided on the choices of advanced porous materials recently adopted in MMMs, including metal–organic frameworks, porous organic frameworks, and porous molecular compounds. Novel trends in MMMs induced by these advanced porous fillers are discussed in detail, followed by a summary of applying these MMMs for gas and liquid separations. Finally, a concise conclusion and current challenges toward the industrial implementation of MMMs are outlined, hoping to provide guidance for the design of high‐performance membranes to meet the urgent needs of clean energy and environmental sustainability.
Benzoxadiazole and Benzoselenadiazole as π‐Bridges in Nonfullerene Acceptors for Efficient Polymer Solar Cells
Authors: Nian Yaowen , Pan Feilong , Li Suhan , Jiang Haiying , Feng Shizhen , Zhang Lianjie , Cao Yong , Chen Junwu
Published: July 2018

Fused‐ring electron acceptors with acceptor‐donor‐acceptor (A‐D‐A) structure have become a hot research field in recent years. In this work, 2,1,3‐benzoxadiazole (BO) and 2,1,3‐benzoselenadiazole (BS) were introduced as π‐bridges between indaceno [1,2‐b : 5,6‐b′] dithiophene (IDT) cores and rhodanine termini for two nonfullerene acceptors IDTBOR and IDTBSR, to compare the structure‐property relationship. Inserting BO as the π‐bridge afforded IDTBOR with deeper LUMO and HOMO levels, whereas BS‐based IDTBSR possessed a smaller optical band gap. With PBDB‐T as polymer donor, IDTBOR‐ and IDTBSR‐based solar cells showed power conversion efficiencies of 7.74 and 6.95%, respectively. A higher open‐circuit voltage of 0.95 V was found for IDTBSR, owing to its up‐lying LUMO level. A higher short‐circuit current density of 15.98 mA/cm2 and fill factor of 54.67% were achieved for IDTBOR, mainly because of the higher electron mobility and better structure order in the blend film. The results suggest that BO and BS units are valuable π‐bridges to construct efficient nonfullerene acceptors.
Demography and life history of a group of white‐bellied spider monkeys (Ateles belzebuth) in western Amazonia
Authors: Link Andrés , Milich Krista , Di Fiore Anthony
Published: July 2018

Species‐specific demographic parameters and life history variables are important for understanding how individual primate taxa have adapted to evolutionary and ecological pressures and for conducting interspecific comparisons as well as for conducting population viability analyses and for managing captive populations. Here, we describe results from a 12+ year study of the demographic dynamics of a wild group of white‐bellied spider monkeys (Ateles belzebuth belzebuth) living near the Tiputini Biodiversity Station in a largely pristine rainforest in western Amazonia. Across the study period, group size varied between 25 and 37 individuals, and there was a clearly female‐biased sex ratio within all age classes. Females were the dispersing sex, as 19 females born into the group disappeared close to reaching adult body size and were presumed to have emigrated, while seven subadult or adult females joined the group during the study period. We estimated the age of dispersal for females at 5.9 ± SD 0.4 years (N = 13). Our study confirms that males are the philopatric sex, as all natal males have remained in the group and some have begun to reproduce, while no males have immigrated. Males began ranging independently from their mothers at ∼4.5 years of age and began copulating with adult females by the age of ∼5 years. Females had long inter‐birth intervals (44.2 ± SD 7.8 months; range: 32–64 months, N = 21). Based on our data, female spider monkeys might have longer life spans than males, as only one out of six adult males but 9 out of 11 adult females present in the group in mid 2005 were still present in January 2018. The slow development and extended life histories of wild spider monkeys pose significant challenges for the ability of these primates to cope with habitat degradation and hunting throughout their geographical distribution.
Chemical Design of Non‐Ionic Polymer Brushes as Biointerfaces: Poly(2‐oxazine)s Outperform Both Poly(2‐oxazoline)s and PEG
Authors: Morgese Giulia , Verbraeken Bart , Ramakrishna Shivaprakash N. , Gombert Yvonne , Cavalli Emma , Rosenboom Jan‐Georg , Zenobi‐Wong Marcy , Spencer Nicholas D. , Hoogenboom Richard , Benetti Edmondo M.
Published: July 2018

The era of poly(ethylene glycol) (PEG) brushes as a universal panacea for preventing non‐specific protein adsorption and providing lubrication to surfaces is coming to an end. In the functionalization of medical devices and implants, in addition to preventing non‐specific protein adsorption and cell adhesion, polymer‐brush formulations are often required to generate highly lubricious films. Poly(2‐alkyl‐2‐oxazoline) (PAOXA) brushes meet these requirements, and depending on their side‐group composition, they can form films that match, and in some cases surpass, the bioinert and lubricious properties of PEG analogues. Poly(2‐methyl‐2‐oxazine) (PMOZI) provides an additional enhancement of brush hydration and main‐chain flexibility, leading to complete bioinertness and a further reduction in friction. These data redefine the combination of structural parameters necessary to design polymer‐brush‐based biointerfaces, identifying a novel, superior polymer formulation.
Stimulus‐induzierte Anion‐Kation‐Exciplexbildung in Kupfer(I)‐Komplexen als Mechanismus für mechanochrome Phosphoreszenz
Authors: Hupp Benjamin , Nitsch Jörn , Schmitt Tanja , Bertermann Rüdiger , Edkins Katharina , Hirsch Florian , Fischer Ingo , Auth Michael , Sperlich Andreas , Steffen Andreas
Published: July 2018

Die mechanistische Untersuchung von mechanochromer Lumineszenz ist sehr wichtig zur Entwicklung von Materialien für die Sensorik, Datenspeicherung oder Lumineszenzschalter. Die strukturelle Ursache in phosphoreszierenden Systemen ist selten bekannt und somit die Aufstellung von Struktur‐Eigenschafts‐Beziehungen eine große Herausforderung. Für d10‐Münzmetallkomplexe wurden Änderungen der M‐M‐Wechselwirkungen als Hauptmechanismus vorgeschlagen. Wir zeigen mit einer mechanisch induzierten, reversiblen Kation‐Anion‐Exciplexbildung, basierend auf Cu‐F‐Interaktionen, einen neuen Mechanismus, der zu sehr effizienter mechanochromer Phosphoreszenz mit für CuI‐Komplexe ungewöhnlich weiten Emissionsverschiebung von UV‐blau zu gelb führt. Die gelbe Lumineszenz ist thermo‐ und vaporesponsiv, wodurch sowohl Weißlicht als auch die ursprüngliche UV‐blaue Emission generiert werden können.
Chemodynamic Therapy: Tumour Microenvironment‐Mediated Fenton and Fenton‐like Reactions
Authors: Tang Zhongmin , Liu Yanyan , He Mingyuan , Bu Wenbo
Published: July 2018

Tailored to the specific tumour microenvironment, which involves acidity and the overproduction of hydrogen peroxide, advanced nanotechnology has been introduced to generate the hydroxyl radical (.OH) primarily for tumour chemodynamic therapy (CDT) through the Fenton and Fenton‐like reactions. Numerous studies have investigated the enhancement of CDT efficiency, primarily the increase in the amount of .OH generated. Notably, various strategies based on the Fenton reaction have been employed to enhance .OH generation, including nanomaterials selection, modulation of the reaction environment, and external energy fields stimulation, which are discussed systematically in this Minireview. Furthermore, the potential challenges and the methods used to facilitate CDT effectiveness are also presented to support this cutting‐edge research area.
Recent updates of fluoroquinolones as antibacterial agents
Authors: Ezelarab Hend A. A. , Abbas Samar H. , Hassan Heba A. , Abuo‐Rahma Gamal El‐Din A.
Published: July 2018

Fluoroquinolones remain one of the most important kind of antibacterial agents used nowadays. The emergence of more virulent and resistant strains of bacteria by the development of either mutated DNA‐binding proteins or efflux pump mechanism for drugs is considered the main problem associated with the therapeutic use of these drugs. This situation participated in pushing researchers to design new fluoroquinolone derivatives, mainly with different substituents at C‐7 to withstand these resistant strains of bacteria and to obtain a wider spectrum of activity including activity against anaerobic organisms. Conjugation of fluoroquinolones with substitutions such as 1,2,4‐triazoles, alkyl oximes, flavonoids, aryl furans, benzofuroxans, metronidazoles or even other antibiotics such as neomycin‐B produced derivatives that have a superior and wider spectrum of activity and better resistance than the classical fluoroquinolone agents. Addition of a hydroxamic acid moiety to fluoroquinolones also increased the activity against Proteus mirabilis, which represents one of the most resistant strains of bacteria in urinary tract infections. This review aims to highlight the recent updates made for fluoroquinolones for broadening the spectrum of activity to become active not only against resistant strains of bacteria but also against anaerobic pathogens.
Social capital and firms' environmental innovations: The moderating role of environmental scanning
Authors: Liao Zhongju
Published: July 2018

Seen as an effective way to balance financial and environmental goals, environmental innovation has become a priority for firms. Based on the theory of social capital, this study examined the antecedents of firms' environmental innovations. Selecting environmental scanning as the moderator, this study analyzed the relationship between the three dimensions of social capital and environmental innovation. Two hundred and forty firms in the manufacturing industry were selected as the sample, and the data were analyzed using SPSS 21.0. The results showed that structural and relational capital had a positive effect on environmental innovation, while the impact of cognitive capital was not significant. Environmental scanning played the role of a positive moderator in the relationships between structural capital, relational capital and environmental innovation. Finally, in accordance with the conclusions, this study proposes related managerial implications and points out future research directions.
Towards Encapsulation of Nanoparticles in Chabazite Through Interzeolite Transformation
Authors: Rasmussen Kristoffer Hauberg , Mielby Jerrik , Kegnæs Søren
Published: July 2018

Encapsulation of Pt nanoparticles (1–2 nm) in the small pore zeolite chabazite (CHA) was achieved by a seed‐ and structure‐directing agent‐free interzeolite transformation from zeolite Y (FAU). Prior to the transformation, the Pt nanoparticles were encapsulated in the commercially available large pore zeolite H−Y by simple incipient wetness impregnation. The H−Y was then converted into CHA in a solution of KOH under hydrothermal conditions at 95 °C. All catalysts were characterized by XRD, N2‐physisorption, H2‐chemisorption, TEM and XPS and their catalytic activity were tested in CO oxidation. Although the catalytic activity of the encapsulated Pt nanoparticles decreased over time, it still remained more active than a reference catalyst prepared by impregnation. The thermal stability of the catalysts was investigated after calcination at 400 °C for 18 hours. Compared to the other catalysts, the encapsulated Pt nanoparticles only resulted in a small decrease in catalytic activity.
Self‐Assembly of Chiral‐at‐End Diketopyrrolopyrroles: Symmetry Dependent Solution and Film Optical Activity and Photovoltaic Performance
Authors: Hume Paul A. , Monks James P. , Pop Flavia , Davies E. Stephen , MacKenzie Roderick C. I. , Amabilino David B.
Published: July 2018

Chiral thiophene‐diketopyrrolopyrrole derivatives have been synthesised to investigate the potential of stereochemistry and symmetry as a means of modulating properties by influencing self‐assembly of these purely organic materials. In particular, derivatives of diketopyrrolopyrrole were employed because of their proven interest as dyes, especially for organic solar cells. The natural product myrtenal was used as the source of stereochemistry, introduced through a Kröhnke reaction of a thiophene‐bearing pyridinium salt and diketopyrrolopyrroles were prepared through Suzuki coupling with this chiral moiety at one end only as well as at both ends. Absorption spectroscopy and electrochemistry confirmed the potential suitability of the compounds for photovoltaic devices. The nanostructures formed by the compounds have been probed with circular dichroism spectroscopy in solution and in films. It is shown that a chiral C2 symmetric molecule assembles in solution giving a strong circular dichroic signal while as a film this optical activity is nulled, whereas an asymmetric homologue is most optically active as a thin film. The X‐ray crystal structure of the asymmetric compound shows a polar order of the molecules that might explain this observation. The lack of optical activity in solution is very likely a result of the high solubility of the compound. The results reaffirm the sensitivity of circular dichroism spectroscopy to inter‐chromophore organisation, whereas absorption spectroscopy in the visible region reveals only slight changes to the bands. The differing order in the compounds also affects their performance in bulk heterojunction photovoltaic devices. Atomic force microscopy of the blended thin films with the fullerene derivative usually employed (PC61BM) showed that smooth and well mixed films were achieved, with the conditions required during spin coating depending greatly on the derivative, because of their differing solubility. The apparently better performance of the symmetrical compound (although with very low efficiency) is probably a result of the alignment of the molecules inferred by the circular dichroism experiments, whereas the asymmetric compound presumably adopts a twisted supramolecular organisation.
A New Protocol to Generate Catalytically Active Species of Group 4–6 Metals by Organosilicon‐Based Salt‐Free Reductants
Authors: Tsurugi Hayato , Mashima Kazushi
Published: July 2018

Herein, we provide a new protocol to reduce various transition‐metal complexes by using organosilicon compounds in a salt‐free fashion with the great advantage of generating pure low‐valent metal species and metallic(0) nanoparticles, in sharp contrast to reductant‐derived salt contaminants obtained by reduction with metal reductants. The organosilicon derivatives 1,4‐bis(trimethylsilyl)‐2,5‐cyclohexadiene (1 a), 1‐methyl‐3,6‐bis(trimethylsilyl)‐1,4‐cyclohexadiene (1 b), 1,4‐bis(trimethylsilyl)‐1,4‐diaza‐2,5‐cyclohexadiene (2 a), 2,5‐dimethyl‐1,4‐bis(trimethylsilyl)‐1,4‐diaza‐2,5‐cyclohexadiene (2 b), 2,3,5,6‐tetramethyl‐1,4‐bis(trimethylsilyl)‐1,4‐diaza‐2,5‐cyclohexadiene (2 c), and 1,1′‐bis(trimethylsilyl)‐1H,1′H‐4,4′‐bipyridinylidene (3) all served as versatile reductants for early transition‐metal complexes and produced only easy‐to‐remove organic compounds, such as trimethylsilylated compounds and the corresponding aromatics, for example, benzene, toluene, pyrazine, and 4,4′‐bipyridyl, as the byproducts. The high solubility of the reductants in organic solvents enabled us to monitor the catalytic reactions directly and to detect any catalytically active species so that we could elucidate the reaction mechanism.
Directed Evolution of a Bond‐Forming Enzyme: Ultrahigh‐Throughput Screening of Microbial Transglutaminase Using Yeast Surface Display
Authors: Deweid Lukas , Neureiter Lara , Englert Simon , Schneider Hendrik , Deweid Jakob , Yanakieva Desislava , Sturm Janna , Bitsch Sebastian , Christmann Andreas , Avrutina Olga , Fuchsbauer Hans‐Lothar , Kolmar Harald
Published: July 2018

Microbial transglutaminase from Streptomyces mobaraensis (mTG) has emerged as a useful biotechnological tool due to its ability to crosslink a side chain of glutamine and primary amines. To date, the substrate specificity of mTG is not fully understood, which poses an obvious challenge when mTG is used to address novel targets. To that end, a viable strategy providing an access to tailor‐made transglutaminases is required. This work reports an ultrahigh‐throughput screening approach based on yeast surface display and fluorescence‐activated cell sorting (FACS) that enabled the evolution of microbial transglutaminase towards enhanced activity. Five rounds of FACS screening followed by recombinant expression of the most potent variants in E. coli yielded variants that possessed, compared to the wild type enzyme, improved enzymatic performance and labeling behavior upon conjugation with an engineered therapeutic anti‐HER2 antibody. This robust and generally applicable platform enables tailoring of the catalytic efficiency of mTG.
Singlet O2 Oxidation of a Deprotonated Guanine‐Cytosine Base Pair and Its Entangling with Intra‐Base‐Pair Proton Transfer
Authors: Lu Wenchao , Sun Yan , Tsai Midas , Zhou Wenjing , Liu Jianbo
Published: July 2018

We report an experimental and computational study on the 1O2 oxidation of gas‐phase deprotonated guanine‐cytosine base pair [G ⋅ C−H]− that is composed of 9HG ⋅ [C−H]− and 7HG ⋅ [C−H]− (pairing 9H‐ or 7H‐guanine with N1‐deprotonated cytosine), and 9HG ⋅ [C−H]−_PT and 7HG ⋅ [C−H]−_PT (formed by intra‐base‐pair proton transfer from the N1 of guanine to the N3 of [C−H]−). The conformer‐averaged reaction product ions and cross section were measured over a center‐of‐mass collision energy range from 0.1 to 0.5 eV using a guided‐ion‐beam tandem mass spectrometer. To explore conformation‐specific reactivity, collision dynamics of 1O2 with each of the four [G ⋅ C−H]− conformers was simulated at B3LYP/6‐31G(d). Trajectories showed that the 1O2 oxidation of the base pair entangles with intra‐base‐pair proton transfer, and prefers to occur in a collision when the base pair adopts a proton‐transferred structure; trajectories also indicate that the 9HG‐containing base pair favors stepwise formation of 4,8‐endoperoxide of guanine, whereas the 7HG‐containing base pair prefers concerted formation of guanine 5,8‐endoperoxide. Using trajectory results as a guide, potential energy surfaces (PESs) along all possible reaction pathways were established using the approximately spin‐projected ωB97XD/6‐311++G(d,p)//B3LYP/6‐311++G(d,p) method. PESs have not only rationalized trajectory findings but provided more accurate energetics and indicated that the proton‐transferred base‐pair conformers have lower activation barriers for oxidation than their non‐proton‐transferred counterparts.
Remote Monitoring for Power Plants—Think Big, Start Small, Scale Fast
Authors: Bickford Randy , Affelt Scott
Published: July 2018

Low power prices have put tremendous pressure on owners of fossil‐fired power generation.
Project Portfolio Management Can Ensure Best Use of Time and Resources
Authors: Schrage Barbara
Published: July 2018

Many organizations struggle with too many projects in the “pipeline” based on limited resource capacity. I have heard numerous stories by attendees of my Project Portfolio Management class at the University of Wisconsin‐Madison of the “pain points” caused by this situation, such as personnel and resources being pulled off one project to work on another and then pulled off that project to work on another one, or personnel working on so many concurrent projects at once that these personnel are overwhelmed with trying to split their time so fine. Then they don't know which project to focus on first.
Atlantic Coast States Obstruct Offshore Wind Despite Saying It's Wanted
Authors: Russo Thomas N.
Published: July 2018

Recent headlines about New York and New Jersey opposing oil and gas production off the Atlantic Coast would have us believe that coastal states have turned a cold shoulder to offshore energy development. Nothing could be further from the truth. In fact, these states and others in New England are hoping that offshore wind development will diversify their electric‐generating fleets and wean them off natural gas.
The effects of intraday news flow on dealers' quotations, market liquidity, and volatility
Authors: Karam Arzé
Published: July 2018

Market regulators emphasize that the reduction in dealers' liquidity to today's markets is one of the drivers of extreme behaviour such as flash crash. Yet the challenge is to understand the effects of intraday news flow on dealers' quoting behaviour, high‐frequency returns, price volatility, liquidity, and trading activity. This paper addresses these issues shortly before the analyst recommendation changes on the Nasdaq. The sample period is 2004 at times where dealers were frequently displaying their quotations on the system. Results show that dealers remain active in quoting, in particular, in the events when the report is issued by their affiliated analysts. Their activity is associated with lower inside spreads, more trading, a more two‐sided market, and lower order imbalance.
Efficient photocatalytic degradation of Acid Red 57 using synthesized ZnO nanowires
Authors: Kiwaan Hala A. , Atwee Tarek M. , Azab Eslam A. , El‐Bindary Ashraf A.
Published: July 2018

Zinc oxide photocatalyst was synthesized through a low‐temperature co‐precipitation process using zinc sulfate as precursor for the degradation of Acid Red 57 (AR57) under UV irradiation. The activities of the prepared photocatalyst at different calcination temperatures (400, 500, and 600 °C) were investigated. The synthesized zinc oxides were characterized by different techniques such as X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, N2 adsorption–desorption, and pH titration for the determination of the zero‐point charge (pHZPC). The efficiency of photocatalytic degradation of ZnO prepared at the calcination temperatures of 400, 500, and 600 °C was 90.03, 77.67, and 72.71%, respectively, after 190 min. The kinetics and scavengers of the reactive species during the degradation were also investigated. It was found that the degradation of AR57 fitted first‐order kinetics and the OH• radicals were the main species. During irradiation, the formation of OH• free radicals was ascertained by photoluminescence studies using terephthalic acid as the probe molecule.
Detection of copy number variants using chromosomal microarray analysis for the prenatal diagnosis of congenital heart defects with normal karyotype
Authors: Song Tingting , Wan Shanning , Li Yu , Xu Ying , Dang Yinghui , Zheng Yunyun , Li Chunyan , Zheng Jiao , Chen Biliang , Zhang Jianfang
Published: July 2018

Background

With the increasing availability of chromosomal microarray analysis (CMA) for congenital heart defect (CHD), genetic testing now faces new challenges due to results with uncertain clinical impact. Studies are needed to better define the penetrance of genetic variants. The aim of the study was to examine the association between CMA and CHDs in fetuses with normal karyotype.

Methods

This was a retrospective study of 190 fetuses with normal karyotype that underwent CMA after a diagnosis of CHD by fetal ultrasound. Invasive prenatal diagnosis was performed between January 2015 and December 2016 at the first affiliated hospital of Air Force Medical University.

Results

Chromosomal microarray analysis detected pathogenic copy number variants (pCNVs) in 13/190 (6.84%) fetuses, likely pCNVs in 5/190 (2.63%), and variants of unknown significance (VOUS) in 14/190 (7.37%). Among those with pCNVs, none (0%) yielded a normal live birth. Among those with likely pCNVs, 2/5 (40.0%) yielded a live birth. Among the fetuses with VOUS, 10/14 (71.5%) yielded a live birth.

Conclusion

These results highlight the usefulness of CMA for prenatal genetic diagnosis of fetuses with CHDs and normal karyotype. In fetuses with CHD, the application of CMA could increase the detection rate of pCNVs causing CHDs. In this study, some VOUS were likely pathogenic, but additional studies are necessary to confirm these findings.
Estimated spatiotemporal variability of total, direct and diffuse solar radiation across China during 1958–2016
Authors: Feng Yao , Li Yuetian
Published: July 2018

The long‐term variability of total, direct and diffuse solar radiation across China during 1958–2016 is investigated based on a ground‐measured daily radiation dataset. Missing data are estimated using a 3‐day average moving window and a backpropagation artificial neural network (BP network). The BP network achieves better estimates of direct (R2 = 0.32–0.96) than diffuse radiation (R2 = 0.00–0.81). A dimming period during 1958–1990 and a “From Dimming to Brightening” transition between 1990 and 1993 have been detected across China. The declining ratio of direct to diffuse radiation suggests a degrading air quality caused by increasing aerosols in eastern China. To study the aerosol effect on radiation, two empirical models are developed from 2000–2016 using the ground‐measured total radiation, sunshine duration and satellite‐retrieved total aerosol concentration. Both models perform well in the estimate of direct (R2 = 0.71–0.89) and diffuse radiation (R2 = 0.63–0.95). The increasing total radiation in eastern China since 2000 is mainly contributed by diffuse radiation. Besides, small anthropogenic aerosols can increase diffuse fraction, the proportion of diffuse in total radiation, whereas large natural aerosols may reduce it. The BP network and empirical models exhibit a better agreement in the estimate of direct than diffuse radiation in eastern China, which highlights the impact of aerosols on diffuse radiation in the recent decade.
Core Job Characteristic and Uncertainty Avoidance: Into the Black Box of Transformational Leadership Effect on Creativity
Authors: Wang Peng
Published: July 2018

Drawing upon the job characteristic model and the “management of meaning” perspective, this study examines the process and conditions through which transformational leadership fosters employee creativity. Our results reveal that the effect of transformational leadership on creativity is mediated by employees’ perceptions of core job characteristics (variety, identity, significance, autonomy, feedback). This mediation effect is further moderated by employees’ uncertainty avoidance orientation. Specifically, transformational leaders foster creativity through followers’ perceptions of core job characteristics only among employees low on uncertainty avoidance. The association between enhanced job characteristics and creativity is more positive for employees with low uncertainty avoidance orientation than those with high uncertainty avoidance orientation. Implications and future research directions are discussed.
A guano‐derived δ13C and δ15N record of climate since the Medieval Warm Period in north‐west Romania
Authors: Cleary Daniel M. , Onac Bogdan P. , Tanţău Ioan , Forray Ferenc L. , Wynn Jonathan G. , Ionita Monica , Tămaş Tudor
Published: July 2018

A 285‐cm core of bat guano was recovered from Măgurici Cave in north‐west Romania and analyzed for δ13C, δ15N and pollen. Guano deposition occurred from AD 881 until 1240 and from AD 1651 to 2013, allowing for the interpretation of summer variations in precipitation and temperature during the Medieval Warm Period (MWP) and the Little Ice Age (LIA). A 2‰ increase in δ13C, 1.5‰ decrease in δ15N, and the presence of Ulmus, Quercus and Carpinus betulus indicate a warm and dry MWP occurred in the region. The lack of deposition during the beginning of the LIA suggests a possible climate‐induced change in prey availability resulting in bats vacating the cave. Variation of δ13C values between −25 and −23‰ at AD 1650 (LIA) indicates similar drier conditions as at the end of MWP. However, a 2‰ decrease in δ13C values that occurred between AD 1790 and 1900 suggests climate was trending towards wetter conditions at the end of the LIA. From AD 1938 to 2013, δ13C values appear to be more influenced by temperature, indicating that this parameter had a more significant effect on carbon discrimination than water availability.
Southern Hemisphere westerly wind influence on southern New Zealand hydrology during the Lateglacial and Holocene
Authors: Anderson Harris J. , Moy Christopher M. , Vandergoes Marcus J. , Nichols Jonathan E. , Riesselman Christina R. , Van Hale Robert
Published: July 2018

The strength and latitudinal position of the southern westerly winds (SWW) influence mid‐latitude precipitation and carbon cycling in the Southern Ocean. Despite the important role the westerlies play in the global climate system, past variability is poorly constrained. Here, we present a geochemical record of hydroclimate change from Lake Von in south‐west New Zealand that spans the last 16 000 years. During the Lateglacial and early Holocene, we find stratigraphic and geochemical evidence for three distinct periods of low lake levels that occur during North Atlantic cold events when the Intertropical Convergence Zone is displaced southwards, Southern Ocean upwelling is enhanced and the Antarctic is rapidly warming. We attribute these hydrological changes to southward shifts of the SWW and associated storm tracks that cause arid conditions in southern New Zealand. During the early Holocene, we find evidence for an extended period of low lake levels that are caused by a combination of diminished wind strength, higher air temperatures and reduced seasonality. Finally, we interpret an overall intensification of the SWW after 5500 cal a bp. Our results support the idea that climate mechanisms originating in the high latitudes and the tropics work together to influence the SWW on millennial timescales.
Dietary lycopene powder improves meat oxidative stability in Hu lambs
Authors: Xu Chenchen , Qu Yanghua , Hopkins David L , Liu Ce , Wang Bo , Gao Yuefeng , Luo Hailing
Published: July 2018

BACKGROUND

The aim of this study was to evaluate the effect of dietary lycopene powder on meat quality and the oxidative stability of lipid and protein of longissimus thoracis (LT) in lamb. A total of 30 male lambs were randomly sampled from three feeding groups (control without lycopene supplement, 200 and 400 mg kg−1 lycopene powder respectively) after 3 months of feeding. The muscle samples were taken after slaughter and stored at 4 °C for 7 days.

RESULTS

Compared with the control, the results showed that supplementation with lycopene powder gave a higher a* value (redness), and increased the levels of vitamin A and vitamin E. Increasing dietary lycopene powder resulted in a lower degree of lipid and protein oxidation, as evidenced by lower contents of thiobarbituric acid‐reactive substance and carbonyl compounds, and higher levels of sulfhydryl groups.

CONCLUSION

Dietary lycopene powder is an effective antioxidant that blocks the oxidation of meat proteins and lipids, and has a positive effect on increasing lamb meat quality during storage. © 2018 Society of Chemical Industry
Development of a highly sensitive high‐performance thin‐layer chromatography method for the screening and simultaneous determination of sofosbuvir, daclatasvir, and ledipasvir in their pure forms and their different pharmaceutical formulations
Authors: Saraya Roshdy E. , Elhenawee Magda , Saleh Hanaa
Published: July 2018

The combination of sofosbuvir and daclatasvir or sofosbuvir and ledipasvir is now widely used as an ideal treatment for hepatitis C virus infection. For this purpose, a simple, sensitive, accurate, economic, and precise high‐performance thin‐layer chromatography was developed and validated for the determination of sofosbuvir, daclatasvir, and ledipasvir in their pure form as well as their different pharmaceutical products. The method used Merck high‐performance thin‐layer chromatography aluminum plates precoated with silica gel 60 F254 as a stationary phase and mobile phase consisting of methylene chloride/methanol/ethyl acetate/ammonia (25%) (6:1:4:1, v/v/v/v). This system was found to give compact symmetric peaks of sofosbuvir, daclatasvir, and ledipasvir with retardation factors of 0.27 ± 0.01, 0.50 ± 0.007, and 0.68 ± 0.008, respectively. The densitometric scanner was set at 275 nm using a deuterium lamp. The calibration curves were linear over the range of 100–3000 ng/spot for sofosbuvir, and daclatasvir, and range of 50–3000 ng/spot for ledipasvir. The detection limits were 22.5, 31.90, and 15.80 for sofosbuvir, daclatasvir, and ledipasvir. The quantitation limits were 67.50, 95.60, and 47.50 for sofosbuvir, daclatasvir, and ledipasvir. The proposed method was validated according to International Conference on Harmonization (ICH) guidelines and the results were acceptable.
Effect of NaAlO2 sealing on corrosion resistance of 2024 aluminum alloy anodized film
Authors: Yang Yingshuo , Cheng Jie , Liu Shengli , Wang Haiyun , Dong Peng
Published: July 2018

In order to effectively improve the corrosion resistance of aluminum alloys, anodic oxidation technique was used to generate the oxide film. Sealing after anodization is an important step to improve the corrosion resistance of aluminum alloys. In this paper, sealing effect of NaAlO2 solution on the oxalic acid anodized aluminum alloy was studied by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), and X‐ray photoelectron spectroscopy (XPS). Experimental results show that unsealed anodized aluminum alloys display a porous structure and have poor corrosion resistance but the pores are filled and the corrosion resistance of the sample is significantly improved when anodized aluminum alloy was immersed in 0.2 m/L NaAlO2 solution with pH of 7 for 5 min at 85 °C. Moreover, the anodized aluminum alloy with NaAlO2 sealing exhibited better corrosion resistance compared to the hydrothermally sealed sample, because of the formation of more AlOOH in NaAlO2 sealing treatment.
Hopf bifurcation in a model for adult T‐cell leukemia
Authors: Mostolizadeh Reihaneh , Afsharnezhad Zahra
Published: July 2018

This paper is concerned with Hopf bifurcation and its stability for the model related to the disease of human T‐cell lymphotropic virus type I (HTLV‐I). In fact, we are considering Hopf bifurcation of the system because it plays an important role in indicating when the disease can return to a steady state condition. The model consists of CD4+T‐cell subsets of healthy, latently infected, and actively infected cells, as well as for leukemia cells. Latently infected T‐cells may harbor the virus for several years until they become activated and able to infect susceptible T‐cells. In this model, we apply techniques such as the center manifold and normal‐form theorem to simplify bifurcating and the dimension of the dynamical system. The results are applied to clinical data as an example.