bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photophysics of Azobenzene Constrained in a UiO Metal–Organic Framework: Effects of Pressure, Solvation and Dynamic Disorder
Authors: Sussardi Alif , Marshall Ross J. , Moggach Stephen A. , Jones Anita C. , Forgan Ross S. 
Published: September 2021

AbstractPhotophysical studies of chromophoric linkers in metal–organic frameworks (MOFs) are undertaken commonly in the context of sensing applications, in search of readily observable changes of optical properties in response to external stimuli. The advantages of the MOF construct as a platform for investigating fundamental photophysical behaviour have been somewhat overlooked. The linker framework offers a unique environment in which the chromophore is geometrically constrained and its structure can be determined crystallographically, but it exists in spatial isolation, unperturbed by inter‐chromophore interactions. Furthermore, high‐pressure studies enable the photophysical consequences of controlled, incremental changes in local environment or conformation to be observed and correlated with structural data. This approach is demonstrated in the present study of the trans‐azobenzene chromophore, constrained in the form of the 4,4’‐azobenzenedicarboxylate (abdc) linker, in a UiO topology framework. Previously unobserved effects of pressure‐induced solvation and conformational distortion on the lowest energy, nπ* transition are reported, and interpreted the light of crystallographic data. It was found that trans‐azobenzene remains non‐fluorescent (with a quantum yield less than 10−4) despite the prevention of trans‐cis isomerization by the constraining MOF structure. We propose that efficient non‐radiative decay is mediated by the local, pedal‐like twisting of the azo group that is evident as dynamic disorder in the crystal structure.
One‐Step Synthesis and Schlenk‐Type Equilibrium of Cyclopentadienylmagnesium Bromides
Authors: Schüler Philipp , Görls Helmar , Krieck Sven , Westerhausen Matthias 
Published: September 2021

AbstractIn the in situ Grignard metalation method (iGMM), the addition of bromoethane to a suspension of magnesium turnings and cyclopentadienes [C5H6 (HCp), C5H5‐Si(iPr)3 (HCpTIPS)] in diethyl ether smoothly yields heteroleptic [(Et2O)Mg(CpR)(μ‐Br)]2 (CpR=Cp (1), CpTIPS (2)). The Schlenk equilibrium of 2 in toluene leads to ligand exchange and formation of homoleptic [Mg(CpR)2] (3) and [(Et2O)MgBr(μ‐Br)]2 (4). Interfering solvation and aggregation as well as ligand redistribution equilibria hamper a quantitative elucidation of thermodynamic data for the Schlenk equilibrium of 2 in toluene. In ethereal solvents, mononuclear species [(Et2O)2Mg(CpTIPS)Br] (2’), [(Et2O)nMg(CpTIPS)2] (3’), and [(Et2O)2MgBr2] (4’) coexist. Larger coordination numbers can be realized with cyclic ethers like tetrahydropyran allowing crystallization of [(thp)4MgBr2] (5). The interpretation of the temperature‐dependency of the Schlenk equilibrium constant in diethyl ether gives a reaction enthalpy ΔH and reaction entropy ΔS of −11.5 kJ mol−1 and 60 J mol−1, respectively.
Electronic Structure and Superconductivity of Compressed Metal Tetrahydrides
Authors: Bi Tiange , Zurek Eva 
Published: September 2021

AbstractTetrahydrides crystallizing in the ThCr2Si2 structure type have been predicted to become stable for a plethora of metals under pressure, and some have recently been synthesized. Through detailed first‐principles investigations we show that the metal atoms within these
symmetry MH4 compounds may be divalent, trivalent or tetravalent. The valence of the metal atom and its radius govern the bonding and electronic structure of these phases, and their evolution under pressure. The factors important for enhancing superconductivity include a large number of hydrogenic states at the Fermi level, and the presence of quasi‐molecular H
units whose bonds have been stretched and weakened (but not broken) via electron transfer from the electropositive metal, and via a Kubas‐like interaction with the metal. Analysis of the microscopic mechanism of superconductivity in MgH4, ScH4 and ZrH4 reveals that phonon modes involving a coupled libration and stretch of the H
units leading to the formation of more complex hydrogenic motifs are important contributors towards the electron phonon coupling mechanism. In the divalent hydride MgH4, modes associated with motions of the hydridic hydrogen atoms are also key contributors, and soften substantially at lower pressures.
Narrow band imaging versus white light for detecting sessile serrated lesion: A prospective randomized multicenter study
Authors: Staudenmann Dominic , Liu Ken , Varma Poornima , Wong May , Rai Sonam , Tsoutsman Tatiana , Choi Kyung Ho , Saxena Payal , Kaffes Arthur John 
Published: September 2021

AbstractObjectivesColonoscopy is the gold standard diagnostic test used to detect early colorectal lesions and prevent colorectal carcinoma. Narrow band imaging (NBI) is an imaging technique that provides improved image resolution of the mucosa during endoscopy. Whether NBI improves the detection of sessile serrated lesion (SSL) is controversial—our aim was to assess this during routine colonoscopy.MethodsWe conducted a multicenter, prospective, randomized, controlled trial. Patients underwent colonoscopy for screening, surveillance, or symptoms. They were randomized to either high‐definition white light (HD‐WL) or NBI in a 1:1 ratio. The primary outcome was SSL detection rate. Secondary outcomes were adenoma detection rate (ADR) and polyp detection rate (PDR).ResultsA total of 400 patients were randomized to NBI (N = 200) or HD‐WL (N = 200). The total colonoscopy time was slightly longer in the NBI group compared to HD‐WL (median time 14 vs. 12 min, p = 0.033). There were no statistically significant differences in SSL detection rate (7.5% NBI vs. 8.0% HD‐WL; p = 0.852), ADR (41.0% NBI vs. 37.5% HD‐WL; p = 0.531), or PDR (61.0% NBI vs. 54.0% HD‐WL; p = 0.157) between the two groups. No significant predictors of SSL detection were found on univariable or multivariable analysis. Increasing age and increased withdrawal time were an independent predictors of polyp detection and increasing age was also an independent predictor of adenoma detection on multivariable analysis.ConclusionIn the hands of experienced colonoscopists, NBI does not improve SSL detection compared to HD‐WL. Withdrawal time and patient age remain important factors for polyp and adenoma detection.
Evolution of winter molting strategies in European and North American migratory passerines
Authors: Pageau Claudie , Sonnleitner Jared , Tonra Christopher M. , Shaikh Mateen , Reudink Matthew W. 
Published: September 2021

AbstractMolt is critical for birds as it replaces damaged feathers and worn plumage, enhancing flight performance, thermoregulation, and communication. In passerines, molt generally occurs on the breeding grounds during the postbreeding period once a year. However, some species of migrant passerines that breed in the Nearctic and Western Palearctic regions have evolved different molting strategies that involve molting on the overwintering grounds. Some species forego molt on the breeding grounds and instead complete their prebasic molt on the overwintering grounds. Other species molt some or all feathers a second time (prealternate molt) during the overwintering period. Using phylogenetic analyses, we explored the potential drivers of the evolution of winter molts in Nearctic and Western Palearctic breeding passerines. Our results indicate an association between longer photoperiods and the presence of prebasic and prealternate molts on the overwintering grounds for both Nearctic and Western Palearctic species. We also found a relationship between prealternate molt and generalist and water habitats for Western Palearctic species. Finally, the complete prealternate molt in Western Palearctic passerines was linked to longer days on the overwintering grounds and longer migration distance. Longer days may favor the evolution of winter prebasic molt by increasing the time window when birds can absorb essential nutrients for molt. Alternatively, for birds undertaking a prealternate molt at the end of the overwintering period, longer days may increase exposure to feather‐degrading ultra‐violet radiation, necessitating the replacement of feathers. Our study underlines the importance of the overwintering grounds in the critical process of molt for many passerines that breed in the Nearctic and Western Palearctic regions.
Persistent yet vulnerable: resurvey of anAbiesecotone reveals few differences but vulnerability to climate change
Authors: Nelson Kellen N. , O’Dean Emily , Knapp Eric E. , Parker Albert J. , Bisbing Sarah M. 
Published: September 2021

AbstractClimate change is shifting forest tree species distributions across elevational and latitudinal gradients, and these changes are often pronounced at ecotones where species meet their climatic bounds and are replaced by other species. Using an extensive ecotone composed of lower‐montane white fir (Abies concolorvar.lowiana) and upper‐montane red fir (Abies magnificavar.magnifica) in the central Sierra Nevada range of California, USA, we (1) examined how the demographics of the ecotone have responded to recent climate using a field observational study and a historical dataset, (2) quantified climate drivers across species life stages using contemporary demographic data, and (3) tested the potential impacts of future climate on species‐specific seedling survival and growth in a fully factorial growth chamber experiment that varied temperature, growing season length, and water availability. A re‐examination of the ecotone midpoint after 35 yr suggested a reduction inA. concolorsapling and tree densities and a rise inA. magnificaproportional dominance between surveys. Seedling abundances across the ecotone indicated thatA. magnificatends to dominate the regeneration layer and currently forms an important component of the seedling community at elevations below those whereA. magnificasaplings or trees begin to co‐dominate stands. Observational and experimental assessments suggest that temperature and precipitation serve as important drivers, differentiatingA. concolorvs.A. magnificadistributions, and are primary stressors at the seedling stage. Seedlings of both species were adversely affected by experimental climate treatments, althoughA. concolorexhibited greater survival and a more conservative growth strategy under extreme climatic stress thanA. magnifica. Projections indicate that historical climate conditions will rise by an amount greater than the ecotone’s current elevational extent by the end of the 21st century. Differential drivers of species abundances suggest that the projected climate will expand conditions that promoteA. concolorabundance and impedeA. magnificaabundance across the ecotone; however, disturbance activity and microclimatic conditions will also influence regeneration and overstory tree dynamics. Our study demonstrates the importance of quantifying species‐specific responses to climate and indicates that widespread regeneration failure may be one possible consequence in which species exhibit strong sensitivity to projected climate conditions.
Zeolitic‐Imidazolate Framework Derived Intermetallic Nickel Zinc Carbide Material as a Selective Catalyst for CO2 to CO Reduction at High Pressure
Authors: Maluf Nágila E. C. , Braga Adriano H. , Gothe Maitê L. , Borges Laís R. , Alves Gustavo A. S. , Gonçalves Renato V. , Szanyi János , Vidinha Pedro , Rossi Liane M. 
Published: August 2021

AbstractThe conversion of CO2 into CO is an important step in CO2 utilization to achieve clean fuels and value‐added chemicals. Herein, we explored the pyrolysis of zeolitic imidazolate framework‐8 (ZIF‐8) loaded with different amounts of Ni2+ to obtain Ni−Zn carbide (Ni3ZnC) embedded in N‐doped carbon. Ni is present in the intermetallic compound, while Zn excess remains on the N‐doped carbon. The Ni3ZnC phase catalyzes the selective hydrogenation of CO2 into CO via the reverse water gas shift reaction, reaching 100 % CO selectivity at ∼30 % CO2 conversion at 450 °C and atmosphere pressure (CO2 : H2=1 : 4, GHSV=30000 mL gcat−1 h−1). The methanation reaction of CO2/CO, which is usually favored over Ni catalysts, is suppressed. The selectivity to CO at the expense of CH4 is related to the stability of chemisorbed CO in the Ni3ZnC surface, which is lower compared to Ni surfaces. The Ni3ZnC@NC catalyst is selective towards CO over a wide range of conditions, including high pressure, that is usually required for the conversion of CO to hydrocarbons and alcohols via the Fisher‐Tropsch synthesis (FTS) process. Contrarily, a classical Ni/SiO2 catalyst prepared by impregnation produces CH4 under high pressure.
A randomized, double blind, parallel, placebo‐controlled study to investigate the efficacy of Lactobacillus paracasei N1115 in gut development of young children
Authors: Wang Shijie , Xun Yiping , Ahern Grace J. , Feng Lili , Zhang Dong , Xue Yuling , Ross Reynolds Paul , Doolan Andrea M. , Stanton Catherine , Zhu Hong 
Published: September 2021

AbstractIn this clinical trial, the safety and effectiveness of Lactobacillus paracasei N1115 (LP N1115) were investigated as a potential probiotic to enhance gut development in young children born by caesarean section. Infants and young children between the ages of 6 months and 3 years were administered with a probiotic consisting of LP N1115 strain (n = 30) or placebo supplement (n = 30) over an 8 weeks intervention. And the stool consistency, bowel habits, salivary cortisol, fecal microbiota, and short‐chain fatty acid metabolism were investigated. Efficacy data were obtained from 58 participants who completed the study. Overall, the placebo functioned similarly to LP N1115 group in relation to stool consistency, gastrointestinal symptoms, salivary cortisol, and short‐chain fatty acids. However, the scoring data relating to the 6–18 months subgroup receiving LP N1115 remained stable over 8 weeks in comparison to placebo. Analysis of the fecal microbiota using 16S rRNA amplicon sequencing revealed that the phyla Firmicutes represented 62% of the microbial relative abundance in the feces of the subjects during the intervening period. No significant changes in alpha‐ or beta‐diversity were noted between the placebo and LP N1115 groups overtime and at each time point. Differential abundance analysis indicated an increase in Lactobacillus in LP N1115 group at weeks 4 (p < .05) and 8 (p < .05) in comparison to the placebo group. These results suggest that probiotic supplementation with LP N1115 was well tolerated by the young children and subtle changes in the microbiome were noted throughout the intervention period.
Highly Stereoselective Aldol Reactions by Memory of Chirality: Synthesis of Quaternary β‐Hydroxy α‐Amino Acids
Authors: Roupnel Loïc , Guillot Régis , Gori Didier , Viswambharan Baby , Kouklovsky Cyrille , Alezra Valérie 
Published: September 2021

AbstractWe describe here an asymmetric aldol reaction based on the principle of Memory of Chirality. From α‐amino acids such as leucine and methionine, we have synthesized in two steps quaternary α‐amino acid derivatives with high diastereoselectivity and enantioselectivity, using the chirality of the initial α‐amino acid as the only chirality source. Furthermore, we were able to determine the relative and absolute configurations of the aldol products thanks to crystallographic structures and thus showed that the relative configuration depended on the aldehyde employed. We proposed a stereoselectivity explanation and obtained also quaternary β‐hydroxy α‐amino acids after acidic hydrolysis.
β‐Caryophyllene may attenuate hyperoxaluria‐induced kidney dysfunction in rats by regulating stress marker KIM‐1/MCP‐1 and NF‐κB signaling pathway
Authors: Xu Xia , Yan Jiamiao 
Published: September 2021

Abstractβ‐Caryophyllene (BCP), a bicyclic sesquiterpene, has proved to exhibit antioxidant and anti‐inflammatory activities. The present study is carried out to investigate BCP impact on hyperoxaluria‐induced kidney dysfunction in male Wistar rats. The animals were categorized into four groups, namely, Group I, control rats; Group II, ethylene glycol (inducer); Group III, inducer + BCP (100 µM/kg bw); Group IV, BCP alone. After the treatment period, the rate of creatinine clearance and the concentration of urea in urine and serum were assessed. Histopathology reports were conducted to study renal and liver tissues, while the reverse transcription‐polymerase chain reaction studies were carried out for messenger RNA expression of inflammatory (nuclear factor kappa B) and endoplasmic reticulum (ER) stress (kidney dysfunction molecule‐1, monocyte chemoattractant protein‐1, glucose binding protein 78, CHOP, activating factor 4, and X‐box binding protein‐1) markers as well as antioxidant activity for the hyperoxaluric rats. Western blot was performed to investigate the level of protein expression by the treatment group on apoptotic (Bcl‐2, Bax, caspase‐3, and caspase‐9) proteins. The results show BCP to possess a renoprotective effect under hyperoxaluric conditions by decreasing the level of the inflammatory and ER stress markers and restoring the enzymes' antioxidant activities. The histology reports depicted the satisfactory morphology of glomerulus in diseased rats. Furthermore, the results of Western blot suggested that BCP may possess inhibitory action on apoptosis by affecting the mitochondrial‐dependent apoptotic pathway. Therefore, BCP can be considered as a potential candidate for the therapy of hyperoxaluric‐induced kidney complications.
Small extracellular vesicles released by infused mesenchymal stromal cells target M2 macrophages and promote TGF‐β upregulation, microvascular stabilization and functional recovery in a rodent model of severe spinal cord injury
Authors: Nakazaki Masahito , Morita Tomonori , Lankford Karen L. , Askenase Philip W , Kocsis Jeffery D. 
Published: September 2021

AbstractIntravenous (IV) infusion of bone marrow‐derived mesenchymal stem/stromal cells (MSCs) stabilizes the blood‐spinal cord barrier (BSCB) and improves functional recovery in experimental models of spinal cord injury (SCI). Although IV delivered MSCs do not traffic to the injury site, IV delivered small extracellular vesicles (sEVs) derived from MSCs (MSC‐sEVs) do and are taken up by a subset of M2 macrophages. To test whether sEVs released by MSCs are responsible for the therapeutic effects of MSCs, we tracked sEVs produced by IV delivered DiR‐labelled MSCs (DiR‐MSCs) after transplantation into SCI rats. We found that sEVs were released by MSCs in vivo, trafficked to the injury site, associated specifically with M2 macrophages and co‐localized with exosome markers. Furthermore, while a single MSC injection was sufficient to improve locomotor recovery, fractionated dosing of MSC‐sEVs over 3 days (F‐sEVs) was required to achieve similar therapeutic effects. Infusion of F‐sEVs mimicked the effects of single dose MSC infusion on multiple parameters including: increased expression of M2 macrophage markers, upregulation of transforming growth factor‐beta (TGF‐β), TGF‐β receptors and tight junction proteins, and reduction in BSCB permeability. These data suggest that release of sEVs by MSCs over time induces a cascade of cellular responses leading to improved functional recovery.
Effects of vine top shading on the accumulation of C6/C9 compounds in 'Cabernet Sauvignon’ (Vitis vinifera L.) grape berries in northwestern China
Authors: Zhang Zhenzhen , Qiao Dan , He Lei , Pan Qiuhong , Wang Shuwei 
Published: September 2021

AbstractBACKGROUNDThe Xinjiang Uygur Autonomous Region is an arid and semi‐arid region with low rainfall and strong sunlight; thus, grape berries in this region accumulate sugar content rapidly, and the ripening process is shorter than that in other regions. Although previous studies illustrated that altered sunlight conditions could influence the aroma profiles of grape berries, less attention has been paid to the effect of vine top shading on volatile compounds under a dry–hot climate.RESULTWe focused on the effects of vine top shading on the concentrations of linolenic and linoleic acids, as well as their metabolites, the C6/C9 compounds, in grape berries. Four vine top shading treatments at veraison (ripening onset) and post‐veraison (skin full coloration) were performed by reducing solar exposure to the grapevines by 20% and 50% respectively. Apart from (E)‐2‐hexenal in the 20% shading treatment of 2016, (E)‐2‐hexenal were not promoted by the 50% shading and 20% shading treatments during veraison to harvest in both of the vintages. By contrast, the influence of vine top shading from post‐veraison till harvest was different between the two vintages; these C6 compounds were decreased in both of the shading treatments in 2016, whereas most of them were promoted in 2017, possibly related to daily sunshine hours in this period. In addition, the C9 compound nonanal with very low concentration exhibits a significant difference among various treatments by two‐factor analysis of variance. As for linolenic acid and linoleic acid, two types of C6 compound biosynthetic precursors, four shading treatments all reduced their concentration, except for linolenic acid in the 50% shading treatment of 2016. Moreover, it appeared to have no apparent correlation between the variations of two precursors and their volatile metabolites, indicating that there is a complex impact of vine shading on C6 compound biosynthesis.CONCLUSIONVine top shading at veraison can reduce the accumulation of some C6 compounds in grape berries, but no consistent consequence was attained for the vine shading at pre‐veraison. The findings indicate the significance of grapevine solar exposure management at veraison in controlling the level of C6 compounds in a dry–hot region like Xinjiang. © 2021 Society of Chemical Industry.
Planck Spectroscopy
Authors: Xiao Yuzhe , Wan Chenghao , Salman Jad , Maywar Ian J. , King Jonathan , Shahsafi Alireza , Kats Mikhail A. 
Published: August 2021

AbstractAll spectrometers rely on some mechanism to achieve spectral selectivity; common examples include gratings, prisms, and interferometers with moving mirrors. A spectroscopic technique—here dubbed Planck spectroscopy—that measures the spectral emissivity of a surface using only a temperature‐controlled stage and a detector, without any wavelength‐selective optical components is experimentally demonstrated and validated. Planck spectroscopy involves the measurement of temperature‐dependent thermally emitted power, where the spectral selectivity is realized via the temperature and wavelength dependence of Planck's law. Planck spectroscopy in the mid infrared, for wavelengths from 3 to 13 µm—limited primarily by the bandwidth of the detector—with resolution of ≈1 µm is experimentally demonstrated and validated. The minimalistic setup of Planck spectroscopy can be implemented using infrared cameras to achieve low‐cost infrared hyperspectral imaging and imaging ellipsometry.