bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Mechanistic Study of the Stereochemical Outcomes of Rhodium‐Catalysed Styrene Aziridinations
Authors: Azek Emna , Spitz Cédric , Ernzerhof Matthias , Lebel Hélène 
Published: November 2019

AbstractThe stereoselective, rhodium‐catalysed aziridination of styrene derivatives with a chiral N‐mesyloxycarbamate was found to be highly substrate dependent. A density functional theory (DFT) study is herein reported to elucidate the stereochemical outcome of the aziridination process. Rhodium acetate was initially used as a model catalyst, followed by computational studies conducted with Rh2[(S)‐nttl]4. Both singlet and triplet rhodium nitrene species were identified as intermediates affording concomitant concerted and radical pathways. In the latter case, the radical intermediate appears to undergo a direct ring closure via a minimum energy crossing point (MECP) between the triplet and closed‐shell singlet surfaces. Exceptionally for the m‐Br‐styrene aziridination, an alternative radical pathway with a carbon‐carbon bond rotation was observed, accounting for the observed 74:26 mixture of diastereomers. The computational analysis also suggests little control of the metal nitrene conformation with Rh2(OAc)4 with the chiral N‐mesyloxycarbamate: two conformers were located affording two diastereomers of the aziridine and correlating our experimental results. On the other hand, only one conformer was found for the nitrene generated from the chiral N‐mesyloxycarbamate and Rh2[(S)‐nttl]4. The so‐called “all‐up” conformer of Rh2[(S)‐nttl]4 was not only the most stable metal nitrene species, but also afforded the lowest energy transition state. The calculated dr for p‐Br‐styrene aziridination agrees with the observed experimental result. The combination of experimental and computational results offers a detailed mechanistic picture, providing insights for further catalyst development to enhance reactivity and selectivity.magnified image
Palladium‐Catalyzed Enantioselective Decarboxylative Allylic Alkylation of Protected Benzoin‐Derived Enol Carbonates
Authors: Lavernhe Rémi , Alexy Eric J. , Zhang Haiming , Stoltz Brian M. 
Published: November 2019

AbstractThe enantioselective palladium‐catalyzed decarboxylative allylic alkylation of fully substituted α‐hydroxy acyclic enol carbonates providing tetrasubstituted benzoin derivatives is reported. Investigation into the transformation revealed that preparation of the starting material as a single enolate isomer is crucial for optimal enantioselectivity. The obtained alkylation products contain multiple reactive sites that can be utilized toward the synthesis of stereochemically rich derivatives.magnified image
The determinants of employability of people living with HIV/AIDS in Turkey
Authors: Özdemir Hülya Özkan , Tosun Selma , Özdemir Durmuş , Korkmaz Elif 
Published: November 2019

AbstractBackgroundThis study addresses an important field within HIV research, the factors affecting the determinants of the employability of people living with HIV/AIDS (PLHIV) in Turkey. The employability of PLHIV is now even more vital because the use of antiretroviral therapy improves the quality of life of patients. In spite of this, the related literature suggests that there are serious impediments to the employment of PLHIV who face considerable levels of discrimination based on their HIV status.MethodsThis is a cohort study of 170 PLHIV of working age, treated at the Izmir Bozyaka Education and Training Hospital. We use a univariate logistic model to determine the effects of all determinants of interest with probit/logit modeling and penalized maximum likelihood estimation to avoid bias and to test the robustness of results.ResultsAge, time since diagnosis, work status at diagnosis, wealth status, illicit drug use, and CD4 cell count were significantly related to the employability of PLHIV. Younger individuals had a higher probability of workforce participation. HIV‐infected patients aged 19 to 39 and 40 to 54 years were 32% and 20% more likely, respectively, to be employed. Economically better‐off PLHIV were more likely to participate in the labor force and HIV patients who were working at the time of diagnosis were more likely to be re‐employed. Time since diagnosis was negatively associated with the employment status. Compared to recently diagnosed patients, PLHIV for more than a decade were less likely to be employed. Those with high CD4 cell counts were more likely to be employed. Illicit drug use was negatively associated with employment and drug‐addicted HIV patients were less likely to be employed. Higher education did not significantly predict the employability of PLHIV.ConclusionsOur results suggest that besides immunological status, socioeconomic factors play a substantial role in the employability of PLHIV. We suggest that even if a patient is skilled, educated, and qualified for the job, other factors such as stigma and employment discrimination in the workplace may hinder employment even among highly educated PLHIV.
Musculoskeletal symptoms associated with workplace physical exposures estimated by a job exposure matrix and by self‐report
Authors: Yung Marcus , Dale Ann Marie , Buckner‐Petty Skye , Roquelaure Yves , Descatha Alexis , Evanoff Bradley A. 
Published: November 2019

AbstractBackgroundA job‐exposure matrix (JEM) is an efficient method to assign physical workplace exposures based on job titles. JEMs offer the possibility of linking work exposures to outcome data from national health registers that contain job titles. The French CONSTANCES JEM was constructed from self‐reported physical work exposures of asymptomatic workers participating in a large general population study. We validated this general population JEM by testing its ability to demonstrate exposure‐outcome associations for musculoskeletal disorders (MSD) symptoms.MethodsThe CONSTANCES JEM was evaluated by assigning exposure estimates to a validation sample of new participants in the CONSTANCES study (final n = 38 730). We used weighted Kappas to compare the level of agreement between JEM‐assigned and self‐reported exposures across job codes for each of the 27 physical exposure variables. We computed prevalence ratios and 95% confidence intervals using Poisson regression models adjusted for age and sex for pain at six body locations associated with work exposures estimated via individual self‐report and by the JEM.ResultsAgreement between individual self‐reported and JEM‐assigned exposures ranged from κ = 0.16 to 0.71; generally, the level of agreement was fair to good. We observed consistent and significant associations between pain and both self‐reported and JEM‐assigned exposures at all body locations.ConclusionsThe CONSTANCES JEM replicated known associations between physical risk factors and prevalent MSD symptoms. Physical exposure JEMs can reduce some types of information bias, and open new avenues of research in the prevention of MSDs and other health conditions related to workplace physical activities.
Occupational exposure to disinfectants and asthma incidence in U.S. nurses: A prospective cohort study
Authors: Dumas Orianne , Boggs Krislyn M. , Quinot Catherine , Varraso Raphaëlle , Zock Jan‐Paul , Henneberger Paul K. , Speizer Frank E. , Le Moual Nicole , Camargo Carlos A. 
Published: November 2019

AbstractBackgroundExposure to disinfectants among healthcare workers has been associated with respiratory health effects, in particular, asthma. However, most studies are cross‐sectional and the role of disinfectant exposures in asthma development requires longitudinal studies. We investigated the association between occupational exposure to disinfectants and incident asthma in a large cohort of U.S. female nurses.MethodsThe Nurses’ Health Study II is a prospective cohort of 116 429 female nurses enrolled in 1989. Analyses included 61 539 participants who were still in a nursing job and with no history of asthma in 2009 (baseline; mean age: 55 years). During 277 744 person‐years of follow‐up (2009‐2015), 370 nurses reported incident physician‐diagnosed asthma. Occupational exposure was evaluated by questionnaire and a Job‐Task‐Exposure Matrix (JTEM). We examined the association between disinfectant exposure and subsequent asthma development, adjusted for age, race, ethnicity, smoking status, and body mass index.ResultsWeekly use of disinfectants to clean surfaces only (23% exposed) or to clean medical instruments (19% exposed) was not associated with incident asthma (adjusted hazard ratio [95% confidence interval] for surfaces, 1.12 [0.87‐1.43]; for instruments, 1.13 [0.87‐1.48]). No association was observed between high‐level exposure to specific disinfectants/cleaning products evaluated by the JTEM (formaldehyde, glutaraldehyde, bleach, hydrogen peroxide, alcohol quats, or enzymatic cleaners) and asthma incidence.ConclusionsIn a population of late career nurses, we observed no significant association between exposure to disinfectants and asthma incidence. A potential role of disinfectant exposures in asthma development warrants further study among healthcare workers at earlier career stage to limit the healthy worker effect.
Discovery, Scope, and Limitations of an N‐Dealkylation/N‐Arylation of Secondary Sulfonamides under Chan−Lam Conditions
Authors: West Matthew J. , Thomson Brodie , Vantourout Julien C. , Watson Allan J. B. 
Published: November 2019

AbstractWe report the discovery, scope, and limitations of a Cu‐mediated sulfonamide N‐dealkylation/N‐arylation reaction. Specific secondary N‐alkyl sulfonamides undergo Cu‐mediated oxidative dealkylation followed by N‐arylation under Chan−Lam conditions. The reaction is relatively general, allowing the synthesis of a range of N‐aryl secondary sulfonamides in good yield. Mechanistic investigations determined the sequence of reaction events as well as the efficiency‐limiting events. Limitations in the methodology are also presented.
A multiyear survey of helminths from wild saddleback (Leontocebus weddelli) and emperor (Saguinus imperator) tamarins
Authors: Erkenswick Gideon A. , Watsa Mrinalini , Gozalo Alfonso S. , Dudaie Shay , Bailey Lindsey , Muranda Kudakwashe S. , Kuziez Alaa , Parker Patricia G. 
Published: November 2019

AbstractThe establishment of baseline data on parasites from wild primates is essential to understand how changes in habitat or climatic disturbances will impact parasite–host relationships. In nature, multiparasitic infections of primates usually fluctuate temporally and seasonally, implying that the acquisition of reliable data must occur over time. Individual parasite infection data from two wild populations of New World primates, the saddleback (Leontocebus weddelli) and emperor (Saguinus imperator) tamarin, were collected over 3 years to establish baseline levels of helminth prevalence and parasite species richness (PSR). Secondarily, we explored variation in parasite prevalence across age and sex classes, test nonrandom associations of parasite co‐occurrence, and assess the relationship between group size and PSR. From 288 fecal samples across 105 individuals (71 saddleback and 34 emperor tamarins), 10 parasite taxa were identified by light microscopy following centrifugation and ethyl‐acetate sedimentation. Of these taxa, none were host‐specific, Dicrocoeliidae and Cestoda prevalences differed between host species,Prosthenorchisand Strongylida were the most prevalent. Host age was positively associated withProsthenorchisova and filariform larva, but negatively with cestode and the Rhabditoidea ova. We detected no differences between expected and observed levels of co‐infection, nor between group size and parasite species richness over 30 group‐years. Logistic models of individual infection status did not identify a sex bias; however, age and species predicted the presence of four and three parasite taxa, respectively, with saddleback tamarins exhibiting higher PSR. Now that we have reliable baseline data for future monitoring of these populations, next steps involve the molecular characterization of these parasites, and exploration of linkages with health parameters.
In‐vitro evaluation of a ciprofloxacin and azithromycin sinus stent for Pseudomonas aeruginosa biofilms
Authors: Lim Dong‐Jin , Skinner Daniel , Mclemore John , Rivers Nick , Elder Jeffrey Brent , Allen Mark , Koch Connor , West John , Zhang Shaoyan , Thompson Harrison M. , McCormick Justin P. , Grayson Jessica W. , Cho Do‐Yeon , Woodworth Bradford A. 
Published: November 2019

BackgroundChronic rhinosinusitis (CRS) is a chronic inflammatory disease characterized by persistent inflammation and bacterial infection. Ciprofloxacin and azithromycin are commonly prescribed antibiotics for CRS, but the ability to provide targeted release in the sinuses could mitigate side effects and improve drug concentrations at the infected site. This study was aimed to evaluate the efficacy of the novel ciprofloxacin‐azithromycin sinus stent (CASS) in vitro.MethodsThe CASS was created by coating ciprofloxacin (hydrophilic, inner layer) and azithromycin (hydrophobic, outer layer) onto a biodegradable poly‐l‐lactic acid (PLLA) stent. In‐vitro evaluation included: (1) assessment of drug‐coating stability within the stent using scanning electron microscopy (SEM); (2) determination of ciprofloxacin and azithromycin release kinetics; and (3) assessment of anti‐biofilm activities against Pseudomonas aeruginosa.ResultsThe ciprofloxacin nanoparticle suspension in the inner layer was confirmed by zeta potential. Both ciprofloxacin (60 µg) and azithromycin (3 mg) were uniformly coated on the surface of the PLLA stents. The CASS showed ciprofloxacin/azithromycin sustained release patterns, with 80.55 ± 11.61% of ciprofloxacin and 93.85 ± 6.9% of azithromycin released by 28 days. The CASS also significantly reduced P aeruginosa biofilm mass compared with bare stents and controls (relative optical density units at 590‐nm optical density: CASS, 0.037 ± 0.006; bare stent, 0.911 ± 0.015; control, 1.000 ± 0.000; p < 0.001; n = 3).ConclusionThe CASS maintains a uniform coating and sustained delivery of ciprofloxacin and azithromycin, providing anti‐biofilm activities against P aeruginosa. Further studies evaluating the efficacy of CASS in a preclinical model are planned.
Characterization of nasal irrigation flow from a squeeze bottle using computational fluid dynamics
Authors: Inthavong Kiao , Shang Yidan , Wong Eugene , Singh Narinder 
Published: November 2019

BackgroundNasal saline irrigation has become standard of care in various sinonasal conditions, including allergic and nonallergic rhinitis, chronic rhinosinusitis, and in the postoperative patient. Evidence regarding the mechanisms and dynamics of liquid flow through the sinonasal cavity remains limited due to inadequate experimental models (cadaveric, 3‐dimensional [3D] printed, imaging of labeled dyes and radioisotopes). We aimed to develop a computational fluid dynamics (CFD) model of nasal irrigation to demonstrate sinonasal surface coverage, residence times across the mucosal surfaces, and shearing force of irrigation.MethodsA nasal cavity geometry derived from high‐resolution paranasal sinus computed tomography (CT) scans of a healthy, unoperated, 25‐year‐old patient was created. CFD analysis was performed to assess the distribution of nasal irrigation from a tapered nozzle bottle at a forward head‐tilt position of 45 degrees with a 2‐second burst at 35 mL/second.ResultsThe model demonstrates nasal irrigation from ipsilateral to contralateral with precise measures of velocity, pressure, wall shear stress, and mapping of surface coverage and residence times at specific locations and times. The nasal cavity experiences almost complete coverage of irrigation, while overflow from the nasal cavity facilitates moderate coverage of the ipsilateral maxillary (40%) and anterior ethmoid sinuses (30%). Negligible coverage of the sphenoid and frontal sinuses was noted.ConclusionDetailed physical mechanisms of liquid irrigation injected from a commonly used squeeze bottle were shown. Ipsilateral maxillary and ethmoid sinus penetration are primarily due to overflow rather than direct jet entry, confirming the recommendation of larger volumes of irrigation to “flood” the sinus ostia.
Unexpected Hole Doping of Graphene by Osmium Adatoms
Authors: Elias Jamie A. , Henriksen Erik A. 
Published: November 2019

AbstractThe electronic transport of monolayer graphene devices is studied before and after in situ deposition of a sub‐monolayer coating of osmium adatoms. Unexpectedly, and unlike all other metallic adatoms studied to date, osmium adatoms shift the charge neutrality point to more positive gate voltages. This indicates that osmium adatoms act as electron acceptors and thus leave the graphene hole‐doped. Analysis of transport data suggest that Os adatoms behave as charged impurity scatterers, albeit with a surprisingly low charge‐doping efficiency. The charge neutrality point of graphene is found to vary non‐monotonically with gate voltage as the sample is warmed to room temperature, suggesting that osmium diffuses on the surface but is not completely removed.
Porphyrin/Quinoidal‐Bithiophene‐Based Macrocycles and Their Dications: Template‐Free Synthesis and Global Aromaticity
Authors: Ren Longbin , Gopalakrishna Tullimilli Y. , Park In‐Hyeok , Han Yi , Wu Jishan 
Published: November 2019

AbstractWe report the template‐free synthesis and characterization of a new type of porphyrin/quinoidal‐bithiophene‐based conjugated macrocycle. X‐ray crystallographic analysis of the dimer (2MC) revealed a cyclophane‐like geometry with large dihedral angles between the porphyrin and the neighboring thiophene rings, and NMR measurements and theoretical calculations confirmed a localized aromatic character of the porphyrin/thiophene rings and quinoidal character of the bithiophene linkers. Restricted rotation of the thiophene rings linked to the porphyrin unit was observed by variable‐temperature NMR measurements. The dication (2MC2+) adopts a chair‐shaped conformation to facilitate π‐electron delocalization around the whole macrocycle. As a result, the molecule is globally aromatic, with a dominant 54 π conjugation pathway. The trimer (3MC) also shows localized aromatic character of porphyrin rings and conformational flexibility, but its dication (3MC2+) is rigid and globally aromatic with a dominant 82 π conjugation pathway.
Blue Light Emitting Defective Nanocrystals Composed of Earth‐Abundant Elements
Authors: Hansen Eric C. , Liu Yun , Utzat Hendrik , Bertram Sophie N. , Grossman Jeffrey C. , Bawendi Moungi G. 
Published: November 2019

AbstractCopper‐based ternary (I–III–VI) chalcogenide nanocrystals (NCs) are compositionally‐flexible semiconductors that do not contain lead (Pb) or cadmium (Cd). Cu‐In‐S NCs are the dominantly studied member of this important materials class and have been reported to contain optically‐active defect states. However, there are minimal reports of In‐free compositions that exhibit efficient photoluminescence (PL). Here, we report a novel solution‐phase synthesis of ≈4 nm defective nanocrystals (DNCs) composed of copper, aluminum, zinc, and sulfur with ≈20 % quantum yield and an attractive PL maximum of 450 nm. Extensive spectroscopic characterization suggests the presence of highly localized electronic states resulting in reasonably fast PL decays (≈1 ns), large vibrational energy spacing, small Stokes shift, and temperature‐independent PL linewidth and PL lifetime (between room temperature and ≈5 K). Furthermore, density functional theory (DFT) calculations suggest PL transitions arise from defects within a CuAl5S8 crystal lattice, which supports the experimental observation of highly‐localized states. The results reported here provide a new material with unique optoelectronic characteristics that is an important analog to well‐explored Cu‐In‐S NCs.
Supramolecular Surface Charge Regulation in Ionic Covalent Organic Nanosheets: Reversible Exfoliation and Controlled Bacterial Growth
Authors: Mal Arindam , Vijayakumar Samiyappan , Mishra Rakesh K. , Jacob Jubi , Pillai Renjith S. , Dileep Kumar B. S. , Ajayaghosh Ayyappanpillai 
Published: November 2019

AbstractPoor control on the exfoliation of covalent organic frameworks (COFs) remains a disadvantage for their application as two‐dimensional nanosheets. An equally important problem is the reversible control at the available surface charges on COFs. Herein, a strategy for the reversible exfoliation, re‐stacking, and surface‐charge control of a propidium iodide based ionic covalent organic framework, PI‐TFP, using cucurbit[7]uril (CB[7]) induced molecular recognition, is reported. The surface charge on PI‐TFP facilitates its initial self‐exfoliation. However, complexation with CB[7] resulted in re‐stacking with concomitant decrease in zeta potential from +28±3.0 to +0.004±0.003 mV. Addition of 1‐adamantylamine hydrochloride (AD) facilitates decomplexation of PI‐TFP from CB[7], resulting in exfoliation and an increase in zeta potential to +24±3.0 mV. Such control on the exfoliation, re‐stacking, and the associated regulation of the surface charge in PI‐TFP was exploited for controlling bacterial growth. Thus, the activity of E. coli and S. aureus bacteria obtained with the self‐exfoliated PI‐TFP could be reversibly controlled by the CB[7]/AD pair.
Nickel‐Catalyzed 1,2‐Diarylation of Alkenyl Carboxylates: A Gateway to 1,2,3‐Trifunctionalized Building Blocks
Authors: Derosa Joseph , Kang Taeho , Tran Van T. , Wisniewski Steven R. , Karunananda Malkanthi K. , Jankins Tanner C. , Xu Kane L. , Engle Keary M. 
Published: November 2019

AbstractA nickel‐catalyzed conjunctive cross‐coupling of alkenyl carboxylic acids, aryl iodides, and aryl/alkenyl boronic esters is reported. The reaction delivers the desired 1,2‐diarylated and 1,2‐arylalkenylated products with excellent regiocontrol. To demonstrate the synthetic utility of the method, a representative product is prepared on gram scale and then diversified to eight 1,2,3‐trifunctionalized building blocks using two‐electron and one‐electron logic. Using this method, three routes toward bioactive molecules are improved in terms of yield and/or step count. This method represents the first example of catalytic 1,2‐diarylation of an alkene directed by a native carboxylate group.
Photoinduced Multiple Effects to Enhance Uranium Extraction from Natural Seawater by Black Phosphorus Nanosheets
Authors: Yuan Yihui , Niu Biye , Yu Qiuhan , Guo Xin , Guo Zhanhu , Wen Jun , Liu Tao , Zhang Haiquan , Wang Ning 
Published: November 2019

AbstractBased on the photoinduced photothermal, photoelectric, and photocatalytic effects of black phosphorus (BP) nanosheets, a BP‐PAO fiber with enhanced uranium extraction capacity and high antibiofouling activity is fabricated by compositing BP nanosheets into polyacrylamidoxime (PAO). The photothermal effect increases the coordination interaction between UO22+ and the functional amidoxime group, and the photoelectric effect produces the surface positive electric field that exhibits electrostatic attraction to the negative [UO2(CO3)3]4−, which all increase the capacity for uranium adsorption. The photocatalytic effect endows the adsorbent with high antibiofouling activity by producing biotoxic reactive oxygen species. Owing to these three photoinduced effects, the photoinduced BP‐PAO fiber shows a high uranium adsorption capacity of 11.76 mg g−1, which is 1.50 times of the PAO fiber, in bacteria‐containing natural seawater.