bluuebunny/crossref_metadata_2025_split huggingface dataset:
n
‐Butyl acrylate [MAK Value Documentation, 2017]
Authors: Hartwig A. ,   MAK Commission
Published: April 2018

Abstract

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 2 ml/m
3
for n‐butyl acrylate. The critical effect in a two‐year inhalation study with rats was reserve cell hyperplasia with loss of ciliated or olfactory cells at the lowest concentration of 15 ml/m
3
. The lower confidence limit of the benchmark dose for an extra risk of 5% increase of the critical effect incidence (BMDL
05
) of about 3 ml/m
3
, which had been calculated in the previous evaluations, was confirmed. Since 2014, the Commission uses an empirical approach to set MAK values for substances with critical effects on the upper respiratory tract or the eyes. Based on this approach, the equivalent concentration at the workplace is 1.5 ml/m
3
. However, studies in humans to investigate the sensory irritation of n‐butyl acrylate are lacking. As the structurally related ethyl acrylate possesses a RD
50
value as well as subchronic and chronic NOAECs similar to those of n‐butyl acrylate, the NOAEC of 2.5 ml ethyl acrylate/m
3
for sensory irritation in volunteers was used as a read‐across. As the MAK value for ethyl acrylate has been set at 2 ml/m
3
, the MAK value of 2 ml/m
3
for n‐butyl acrylate could be confirmed. In analogy to ethyl acrylate, the assignment of n‐butyl acrylate to Peak Limitation Category I and the excursion factor of 2 were confirmed. The NOAECs for developmental toxicity in rats and mice are sufficiently high so that damage to the embryo or foetus is unlikely when the MAK value is observed. Thus, n‐butyl acrylate continues to be classified in Pregnancy Risk Group C. The substance is marginally clastogenic in vitro but not in vivo and was not carcinogenic in a 2‐year inhalation study in rats. There are only a few cases of contact sensitization in humans but there are positive results in local lymph node assays. Data on airway sensitization are still not available. n‐Butyl acrylate continues to be designated with “Sh”. Skin absorption was calculated to contribute significantly to the systemic toxicity and n‐butyl acrylate is designated with an “H”.
1,3‐Dioxolan [MAK Value Documentation in German language, 2018]
Authors: Hartwig A. ,   MAK Commission
Published: April 2018

Abstract

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) and the Pregnancy Risk Group of 1,3‐dioxolane [
646‐06‐0
].

1,3‐Dioxolane causes a reduction in white blood cell count and in relative spleen weight at 1000 ml/m
3
and above in female rats after 13 weeks whole body inhalation. The NOAEC is 298 ml/m
3
. As the percentage of white blood cell count reduction is the same after four and 13 weeks, no decrease of the NOAEC after chronic exposure is expected. The former MAK value of 100 ml/m
3
was derived from the NOAEC. The MAK value is now lowered to 50 ml/m
3
which takes into account the increased respiratory volume at the workplace because the blood:air partition coefficient of 1,3‐dioxolane is > 5 (see List of MAK‐ and BAT values chapters I b and I c). Since a systemic effect is critical, Peak Limitation Category II is retained. The default excursion factor of 2 is retained as well, as no half‐life in blood is known.

In a prenatal toxicity study in rats with gavage application, 1,3‐dioxolane results in reduced fetal body weights and gross external, soft tissue and skeletal malformations or variations at 1000 mg/kg body weight and day. The NOAEL for developmental toxicity is 500 mg/kg body weight and day. After toxicokinetic scaling this dose corresponds to a concentration of 875 mg/m
3
(285 ml/m
3
) at the workplace. The difference to the MAK value of 50 ml/m
3
is not sufficient. Therefore, the assignment to Pregnancy Risk Group B, for substances, for which damage to the embryo or foetus must be expected even when the MAK value is observed, is confirmed.
N‐Vinyl‐2‐pyrrolidon [MAK Value Documentation in German language, 2018]
Authors: Hartwig A. ,   MAK Commission
Published: April 2018

Abstract

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) and the Pregnancy Risk Group of N‐vinyl‐2‐pyrrolidone [
88‐12‐0
].

N‐Vinyl‐2‐pyrrolidone is a non‐genotoxic carcinogen in liver, nose and larynx of rats. In 28‐day inhalation studies it was shown that cell proliferation in liver and hyperplasia in the nasal epithelia of rats is increased at 0.5 ml/m
3
with a NOAEC of 0.2 ml/m
3
. The former MAK value of 0.02 ml/m
3
was derived from this concentration, the MAK value is now lowered to 0.01 ml/m
3
. This takes into account the increased respiratory volume at the workplace, because the blood:air partition coefficient of N‐vinyl‐2‐pyrrolidone is > 5 (see List of MAK‐ and BAT values chapters I b and I c). Since a systemic effect is critical, Peak Limitation Category II is retained. As the critical metabolite is not known, the default excursion factor of 2 for systemically acting compounds is confirmed.

For rats, the NOAEC for developmental toxicity after inhalation is 5 ml N‐vinyl‐2‐pyrrolidone/m
3
, where reduced maternal body weight gain occurred. At 20 ml/m
3
reduced foetal bodyweight and an increase of variations were observed. Taking into account the increased respiratory volume at the work place the NOAEC for developmental toxicity is 250 times higher than the MAK‐value. Therefore, N‐vinyl‐2‐pyrrolidone remains assigned to Pregnancy Risk Group C.
Synthesis of 2D Metal Chalcogenide Thin Films through the Process Involving Solution‐Phase Deposition
Authors: Giri Anupam , Park Gyeongbae , Yang Heeseung , Pal Monalisa , Kwak Junghyeok , Jeong Unyong 
Published: April 2018

Abstract2D metal chalcogenide thin films have recently attracted considerable attention owing to their unique physicochemical properties and great potential in a variety of applications. Synthesis of large‐area 2D metal chalcogenide thin films in controllable ways remains a key challenge in this research field. Recently, the solution‐based synthesis of 2D metal chalcogenide thin films has emerged as an alternative approach to vacuum‐based synthesis because it is relatively simple and easy to scale up for high‐throughput production. In addition, solution‐based thin films open new opportunities that cannot be achieved from vacuum‐based thin films. Here, a comprehensive summary regarding the basic structures and properties of different types of 2D metal chalcogenides, the mechanistic details of the chemical reactions in the synthesis of the metal chalcogenide thin films, recent successes in the synthesis by different reaction approaches, and the applications and potential uses is provided. In the last perspective section, the technical challenges to be overcome and the future research directions in the solution‐based synthesis of 2D metal chalcogenides are discussed.
Melanoma, thyroid cancer, and gynecologic cancers in a cohort of female flight attendants
Authors: Pinkerton Lynne E. , Hein Misty J. , Anderson Jeri L. , Christianson Annette , Little Mark P. , Sigurdson Alice J. , Schubauer‐Berigan Mary K. 
Published: April 2018

BackgroundFlight attendants may have an increased risk of some cancers from occupational exposure to cosmic radiation and circadian disruption.MethodsThe incidence of thyroid, ovarian, and uterine cancer among ∼6000 female flight attendants compared to the US population was evaluated via life table analyses. Associations of these cancers, melanoma, and cervical cancer with cumulative cosmic radiation dose and metrics of circadian disruption were evaluated using Cox regression.ResultsIncidence of thyroid, ovarian, and uterine cancer was not elevated. No significant, positive exposure‐response relations were observed. Weak, non‐significant, positive relations were observed for thyroid cancer with cosmic radiation and time zones crossed and for melanoma with another metric of circadian disruption.ConclusionsWe found little evidence of increased risk of these cancers from occupational cosmic radiation or circadian disruption in female flight attendants. Limitations include few observed cases of some cancers, limited data on risk factors, and misclassification of exposures.
Fucose‐Migration in intakten protonierten Glykan‐Ionen – ein universelles Phänomen in der Massenspektrometrie
Authors: Mucha Eike , Lettow Maike , Marianski Mateusz , Thomas Daniel A. , Struwe Weston B. , Harvey David J. , Meijer Gerard , Seeberger Peter H. , von Helden Gert , Pagel Kevin 
Published: April 2018

AbstractFucose ist ein essenzieller Desoxyzucker, der in einer Vielzahl biologisch relevanter Glykane und ihrer Konjugate vorkommt. Ein verbreitetes Problem in massenspektrometrischen Analysen von fucosylierten Glykanen ist der intramolekulare Transfer von Fucoseeinheiten, der zu fehlerhaften Sequenzzuordnungen führen kann. Diese Migrationsreaktion wird typischerweise der Aktivierung während der kollisionsinduzierten Dissoziation in der Tandem‐Massenspektrometrie (Tandem‐MS) zugeordnet. Hier wird erstmals mit Kaltionen‐Spektroskopie gezeigt, dass Fucose‐Migration nicht auf Fragmente beschränkt ist, die in der Tandem‐MS erhalten werden, sondern auch in intakten Glykan‐Ionen beobachtet werden kann. Diese Beobachtung lässt auf eine mögliche niedrige Energiebarriere für diese Transferreaktion schließen und verallgemeinert die Fucose‐Migration zu einem Problem, das bei jeder Art von Massenspektrometrie‐Experiment auftreten kann.
Asymmetrische reduktive Carbocyclisierung durch modifizierte En‐Reduktasen
Authors: Heckenbichler Kathrin , Schweiger Anna , Brandner Lea Alexandra , Binter Alexandra , Toplak Marina , Macheroux Peter , Gruber Karl , Breinbauer Rolf 
Published: April 2018

AbstractEn‐Reduktasen der “Old Yellow Enzyme”(OYE)‐Familie reduzieren die C=C‐Doppelbindung in α,β‐ungesättigten Verbindungen, die eine elektronenziehende Gruppe (z. B. eine Carbonyl‐Gruppe) tragen. Diese asymmetrische Reduktion hat in der Biokatalyse Anwendung gefunden. Es konnte gezeigt werden, dass Mitglieder dieser Enzymfamilie außerdem noch die Bildung von C‐C‐Bindungen katalysieren können. Mit α,β‐ungesättigten Aldehyden und Ketonen, die eine zusätzliche elektrophile Gruppe enthalten, kann eine reduktive Cyclisierung erfolgen. Dabei überträgt der durch zwei Elektronen reduzierte Enzymcofaktor FMN ein Hydrid. Das entstandene Enolat kann danach mit einem internen Elektrophil unter Ringbildung reagieren. Ortsgerichteter Austausch des entscheidenden Tyr‐Rests gegen ein nichtprotisches Phe oder Trp begünstigt die reduktive Cyclisierung über die natürliche Reduktionsreaktion. Diese neue Transformation ermöglicht die enantioselektive Synthese von chiralen Cyclopropanen mit bis zu >99 % ee.
Smart DNA Hydrogel Integrated Nanochannels with High Ion Flux and Adjustable Selective Ionic Transport
Authors: Wu Yafeng , Wang Dianyu , Willner Itamar , Tian Ye , Jiang Lei 
Published: April 2018

AbstractNanochannels based on smart DNA hydrogels as stimulus‐responsive architecture are presented for the first time. In contrast to other responsive molecules existing in the nanochannel in monolayer configurations, the DNA hydrogels are three‐dimensional networks with space negative charges, the ion flux and rectification ratio are significantly enhanced. Upon cyclic treatment with K+ ions and crown ether, the DNA hydrogel states could be reversibly switched between less stiff and stiff networks, providing the gating mechanism of the nanochannel. Based on the architecture of DNA hydrogels and pH stimulus, cation or anion transport direction could be precisely controlled and multiple gating features are achieved. Meanwhile, G‐quadruplex DNA in the hydrogels might be replaced by other stimulus‐responsive DNA molecules, peptides, or proteins, and thus this work opens a new route for improving the functionalities of nanochannel by intelligent hydrogels.
Ein rein organisches Tricarbanion
Authors: Höfler Denis , Goddard Richard , Lingnau Julia B. , Nöthling Nils , List Benjamin 
Published: April 2018

AbstractWie viele Carbanionen kann ein organisches Molekül tragen? Die Bildung von rein organischen Carbanionen mit mehreren Ladungen ist eine anspruchsvolle Aufgabe, da eine Ladungsstabilisierung nicht durch Metallkoordination erreicht werden kann. Bisher wurden nur Salze von quartären Ammoniumdicarbanionen beschrieben. Mit stark elektronenarmen Trifluormethansulfonylgruppen konnte jetzt erstmals die Bildung eines rein organischen Tricarbanions erzielt werden.
Asymmetric Reductive Carbocyclization Using Engineered Ene Reductases
Authors: Heckenbichler Kathrin , Schweiger Anna , Brandner Lea Alexandra , Binter Alexandra , Toplak Marina , Macheroux Peter , Gruber Karl , Breinbauer Rolf 
Published: April 2018

AbstractEne reductases from the Old Yellow Enzyme (OYE) family reduce the C=C double bond in α,β‐unsaturated compounds bearing an electron‐withdrawing group, for example, a carbonyl group. This asymmetric reduction has been exploited for biocatalysis. Going beyond its canonical function, we show that members of this enzyme family can also catalyze the formation of C−C bonds. α,β‐Unsaturated aldehydes and ketones containing an additional electrophilic group undergo reductive cyclization. Mechanistically, the two‐electron‐reduced enzyme cofactor FMN delivers a hydride to generate an enolate intermediate, which reacts with the internal electrophile. Single‐site replacement of a crucial Tyr residue with a non‐protic Phe or Trp favored the cyclization over the natural reduction reaction. The new transformation enabled the enantioselective synthesis of chiral cyclopropanes in up to >99 % ee.
A Purely Organic Tricarbanion
Authors: Höfler Denis , Goddard Richard , Lingnau Julia B. , Nöthling Nils , List Benjamin 
Published: April 2018

AbstractHow many carbanions can an organic molecule accommodate? The formation of purely organic carbanions with multiple charges is challenging as charge stabilization cannot be achieved through metal coordination. Previously, only quaternary ammonium dicarbanion salts had been reported. By using highly electron‐deficient trifluoromethanesulfonyl (triflyl or Tf) groups, the formation of a purely organic tricarbanion has been realized for the first time.
The size effect to O2−–Ce4+ charge transfer emission and band gap structure of Sr2CeO4
Authors: Wang Wenjun , Pan Yu , Zhang Wenying , Liu Xiaoguang , Li Ling 
Published: April 2018

AbstractSr2CeO4 phosphors with different crystalline sizes were synthesized by the sol–gel method or the solid‐state reaction. Their crystalline size, luminescence intensity of O2−−Ce4+ charge transfer and energy gaps were obtained through the characterization by X‐ray diffraction, photoluminescence spectra, as well as UV–visible diffuse reflectance measurements. An inverse relationship between photoluminescence (PL) spectra and crystalline size was observed when the heating temperature was from 1000°C to 1300°C. In addition, band energy calculated for all samples showed that a reaction temperature of 1200°C for the solid‐state method and 1100°C for sol–gel method gave the largest values, which corresponded with the smallest crystalline size. Correlation between PL intensity and crystalline size showed an inverse relationship. Band structure, density of states and partial density of states of the crystal were calculated to analyze the mechanism using the cambrige sequential total energy package (CASTEP) module integrated with Materials Studio software.
Hollow Nickel–Cobalt Layered Double Hydroxide Supported Palladium Catalysts with Superior Hydrogen Evolution Activity for Hydrolysis of Ammonia Borane
Authors: Zhou Ying‐Hua , Wang Suqin , Zhang Zhiyan , Williams Nicholas , Cheng Yong , Gu Jing 
Published: April 2018

AbstractAlthough ammonia borane (NH3BH3, AB) has been identified as an excellent hydrogen‐storage medium, the development of a highly active catalyst that can function under mild conditions for controllable hydrogen release is still a great challenge. The synergistic effect induced by interactions between metal nanoparticles and a support has been widely applied in thermocatalytic conversion processes. In this work, Pd nanoparticles (NPs) highly dispersed on hollow NiCo layered double hydroxide (LDH) were designed for efficient hydrogen generation from AB at room temperature. During the hydrolytic dehydrogenation of AB, Pd/α‐LDH and Pd/β‐LDH exhibited catalytic activities with total turnover frequency (TOF) values of 49.5 and 28.1 min−1 with activation energy (Ea) values of 20.56 and 37.56 kJ mol−1, respectively, at 298 K; thus, these catalysts outperform most Pd‐based catalysts. The improved catalytic effect was attributed to the controllable size and fine distribution of the Pd NPs and the collaborative effect provided by the hydroxide of α‐LDH and the intercalated anions (HO−). This catalysts design principle can be easily transferred to other catalyst research fields for energy‐conversion and ‐storage purposes.
Transition‐Metal‐Catalyzed C−H Functionalization for Construction of Quaternary Carbon Centers
Authors: Li Yang , Xu Silong 
Published: April 2018

AbstractEfficient construction of quaternary carbon centers represents one of the most challenging goals in organic synthesis, and it has drawn tremendous research interest from organic chemist community. The past decade has witnessed a significant advancement of direct C−H functionalization, which delivers various synthetic tools for assembling structurally diversified architectures with the advantage of step‐ and atom‐economy, operational simplicity, and readily available substrates. In this Minireview, synthetic methods based on transition‐metal‐catalyzed C−H functionalization as efficient tools for the construction of quaternary carbon centers are summarized.
DFT Studies on the Reactions of Boroles with Alkynes
Authors: Wang Zheng , Zhou Yu , Zhang Jing‐Xuan , Krummenacher Ivo , Braunschweig Holger , Lin Zhenyang 
Published: April 2018

AbstractDFT calculations were performed to investigate the reactions of boroles with alkynes, in which boranorbornadiene, borepin and/or boracyclohexadiene can be formed depending on the substituents on the borole and alkyne. Our computational results indicated that formation of boranorbornadiene and borepin is generally kinetically favoured and that the products can interconvert. Formation of boracyclohexadiene is kinetically unfavourable in most reactions. However, certain substituents can promote the formation of boracyclohexadiene by stabilizing an energetically high‐lying zwitterionic transition state that leads to boracyclohexadiene. Borafluorene reacted with most alkynes to give borepin exclusively due to its propensity to maintain its aromaticity. However, when it reacted with silyl‐substituted alkyne(s), a novel product, different from boranorbornadiene, borepin and boracyclohexadiene was generated, which can be attributed to the well‐known ability of silyl groups to migrate.
CHA2DS2‐VASc score and clinical outcomes of patients with chest pain discharged from internal medicine wards following acute coronary syndrome rule‐out
Authors: Topaz Guy , Haisraely Ory , Shacham Yacov , Beery Gil , Shilo Lotan , Kassem Nuha , Pereg David , Kitay‐Cohen Yona 
Published: April 2018

BackgroundChest‐pain patients deemed safe for discharge from internal medicine wards might still be at risk for adverse outcomes.HypothesisCHA2DS2‐VASc score improves risk stratification of low‐risk chest‐pain patients discharged after acute coronary syndrome (ACS) rule‐out.MethodsWe accessed medical records of patients who were admitted to internal medicine wards at a single medical center during 2010–2016 and discharged following an ACS rule‐out. Patients were classified according to CHA2DS2‐VASc score: 0–1 (low), 2–3 (intermediate), >3 (high). Primary endpoint was occurrence of ACS at 1 year; 30‐day and 1‐year all‐cause mortality (ACM) were secondary outcomes.ResultsOf 12 449 patients, 7057 (57%) had low, 3781 (30%) intermediate, and 1611 (13%) high CHA2DS2‐VASc scores. Compared with a low score, intermediate and high scores were associated with significantly increased risk for 1‐year ACS during the first year (OR: 2.89, 95% CI: 1.91–4.37, P < 0.01 and OR: 4.84, 95% CI: 3.02–7.74, P < 0.01, respectively). Each 1‐point increase in CHA2DS2‐VASc was associated with a 37% increased risk for 1‐year ACS. A higher CHA2DS2‐VASc score was associated with significantly higher 30‐day ACM. Hazard ratios for 30‐day ACM were 1.9 (95% CI: 1.1–3.4, P = 0.03) and 4.4 (95% CI: 2.4–7.9, P < 0.01) for intermediate and high CHA2DS2‐VASc scores, respectively, compared with a low score. Each 1‐point increase in CHA2DS2‐VASc score was associated with 43% increased risk for 30‐day mortality.ConclusionsHigh CHA2DS2‐VASc score (>3) was associated with adverse outcomes among chest‐pain patients discharged from internal medicine wards following ACS rule‐out.
A novel adaptive radio map for RSS‐based indoor positioning
Authors: Ye Ayong , Yang Xiaoliang , Li Qing , Chen Aimin 
Published: April 2018

SummaryFingerprinting positioning is used for indoor location estimation because of low cost and open access properties, in which a radio map is built by calibrating signal‐strength values at several training locations in the offline phase. However, due to the sophisticated propagation of radio signals, the received signal strength (RSS) in wireless network change as the environment changes, and the radio map built in the offline phase may be out of date. Furthermore, the recalibration of signal‐strength values for each environment change is laborious and time consuming. In this paper, we present a novel algorithm to reconstruct a radio map using real‐time signal‐strength readings received at some reference points. We first demonstrate that different features of signal propagation are obtained in different regions of indoor environment. Then, the indoor environment is divided into several regions by clustering the path‐loss parameters of each reference point. In addition, the relationship between the RSS of reference points and calibration nodes is established with robust linear regression. Finally, the real‐time radio map is updated dynamically according to robust regression and the real‐time RSSs of the calibration nodes. The experimental results show the usefulness of the proposed method and the accuracy of the localization can be improved.
Evaluation of dataflow programming models for electronic structure theory
Authors: Jagode Heike , Danalis Anthony , Hoque Reazul , Faverge Mathieu , Dongarra Jack 
Published: April 2018

SummaryDataflow programming models have been growing in popularity as a means to deliver a good balance between performance and portability in the post‐petascale era. In this paper, we evaluate different dataflow programming models for electronic structure methods and compare them in terms of programmability, resource utilization, and scalability. In particular, we evaluate two programming paradigms for expressing scientific applications in a dataflow form: (1) explicit dataflow, where the dataflow is specified explicitly by the developer, and (2) implicit dataflow, where a task scheduling runtime derives the dataflow using per‐task data‐access information embedded in a serial program. We discuss our findings and present a thorough experimental analysis using methods from the NWChem quantum chemistry application as our case study, and OpenMP, StarPU, and PaRSEC as the task‐based runtimes that enable the different forms of dataflow execution. Furthermore, we derive an abstract model to explore the limits of the different dataflow programming paradigms.