bluuebunny/crossref_metadata_2025_split huggingface dataset:
N‐Acyl Derivatives of 4‐Phenoxyaniline as Neuroprotective Agents
Authors: Barho Marlene T. , Oppermann Sina , Schrader Florian C. , Degenhardt Inga , Elsässer Katharina , Wegscheid‐Gerlach Christof , Culmsee Carsten , Schlitzer Martin 
Published: July 2014

AbstractNeuronal cell death is the main cause behind the progressive loss of brain function in age‐related neurodegenerative disorders such as Alzheimer’s and Parkinson’s diseases. Despite the differing etiologies of these neurological diseases, the underlying neuronal damage is triggered by common mechanisms such as oxidative stress, impaired calcium homeostasis, and disrupted mitochondrial integrity and function. In particular, mitochondrial fragmentation, mitochondrial membrane permeability, and the release of death‐promoting factors into the cytosol have been revealed as the “point of no return” in programmed cell death in neurons. Recent studies revealed a pivotal role for the pro‐apoptotic Bcl‐2‐family protein Bid in models of neuronal cell death, which confirmed Bid as a potential drug target. Herein, we present N‐acyl‐substituted derivatives of 4‐phenoxyaniline that were screened for their potential to attenuate Bid‐mediated neurotoxicity. These compounds provided significant protection against glutamate‐ and Bid‐induced toxicity in cultured neurons. Substitution of the amino group in the 4‐phenoxyaniline scaffold with 4‐piperidine carboxylic acid and N‐hydroxyethyl‐4‐piperidine carboxylic acid yielded compounds that displayed significant neuroprotective activity at concentrations as low as 1 μM. Furthermore, findings of a tBid‐overexpression assay and real‐time measurements of cell impedance support the hypothesis that these compounds indeed address the Bid protein.
Indolicidin Targets Duplex DNA: Structural and Mechanistic Insight through a Combination of Spectroscopy and Microscopy
Authors: Ghosh Anirban , Kar Rajiv Kumar , Jana Jagannath , Saha Abhijit , Jana Batakrishna , Krishnamoorthy Janarthanan , Kumar Dinesh , Ghosh Surajit , Chatterjee Subhrangsu , Bhunia Anirban 
Published: July 2014

AbstractIndolicidin (IR13), a 13‐residue antimicrobial peptide from the cathelicidin family, is known to exhibit a broad spectrum of antimicrobial activity against various microorganisms. This peptide inhibits bacterial DNA synthesis resulting in cell filamentation. However, the precise mechanism remains unclear and requires further investigation. The central PWWP motif of IR13 provides a unique structural element that can wrap around, and thus stabilize, duplex B‐type DNA structures. Replacements of the central Trp‐Trp pair with Ala‐Ala, His‐His, or Phe‐Phe residues in the PxxP motif significantly affects the ability of the peptide to stabilize duplex DNA. Results of microscopy studies in conjunction with spectroscopic data confirm that the DNA duplex is stabilized by IR13, thereby inhibiting DNA replication and transcription. In this study we provide high‐resolution structural information on the interaction between indolicidin and DNA, which will be beneficial for the design of novel therapeutic antibiotics based on peptide scaffolds.
Defective α‐Fe2O3(0001): An ab Initio Study
Authors: Nguyen Manh‐Thuong , Seriani Nicola , Gebauer Ralph 
Published: July 2014

AbstractBy using density functional theory calculations at the PBE+U level, we investigated the properties of hematite (0001) surfaces decorated with adatoms/vacancies/substituents. For the most stable surface termination over a large range of oxygen chemical potentials (${\mu _{\rm{O}} }$), the vacancy formation and adsorption energies were determined as a function of ${\mu _{\rm{O}} }$. Under oxygen‐rich conditions, all defects are metastable with respect to the ideal surface. Under oxygen‐poor conditions, O vacancies and Fe adatoms become stable. Under ambient conditions, all defects are metastable; in the bulk, O vacancies form more easily than Fe vacancies, whereas at the surface the opposite is true. All defects, that is, O and Fe vacancies, Fe and Al adatoms, and Al substituents, induce important modifications to the geometry of the surface in their vicinity. Dissociative adsorption of molecular oxygen is likely to be exothermic on surfaces with Fe/Al adatoms or O vacancies.
Graphene Oxides Prepared by Hummers’, Hofmann’s, and Staudenmaier’s Methods: Dramatic Influences on Heavy‐Metal‐Ion Adsorption
Authors: Moo James Guo Sheng , Khezri Bahareh , Webster Richard D. , Pumera Martin 
Published: July 2014

AbstractGraphene oxide (GO), an up‐and‐coming material rich in oxygenated groups, shows much promise in pollution management. GO is synthesised using several synthetic routes, and the adsorption behaviour of GO is investigated to establish its ability to remove the heavy‐metal pollutants of lead and cadmium ions. The GO is synthesised by Hummers’ (HU), Hofmann’s (HO) and Staudenmaier’s (ST) methodologies. Characterisation of GO is performed before and after adsorption experiments to investigate the structure–function relationship by using Fourier‐transform infrared spectroscopy and X‐ray photoelectron spectroscopy. Scanning electron microscopy coupled with elemental detection spectroscopy is used to investigate morphological changes and heavy‐metal content in the adsorbed GO. The filtrate, collected after adsorption, is analysed by inductively coupled plasma mass spectrometry, through which the efficiency and adsorption capacity of each GO for heavy‐metal‐ion removal is obtained. Spectroscopic analysis and characterisation reveal that the three types of GO have different compositions of oxygenated carbon functionalities. The trend in the affinity towards both PbII and CdII is HU GO>HO GO>ST GO. A direct correlation between the number of carboxyl groups present and the amount of heavy‐metal ions adsorbed is established. The highest efficiency and highest adsorption capacity of heavy‐metal ions is achieved with HU, in which the relative abundance of carboxyl groups is highest. The embedded systematic study reveals that carboxyl groups are the principal functionality responsible for heavy‐metal‐ion removal in GO. The choice of synthesis methodology for GO has a profound influence on heavy‐metal‐ion adsorption. A further enrichment of the carboxyl groups in GO will serve to enhance the role of GO as an adsorbent for environmental clean‐up.
Water OH Bond Activation by Gas‐Phase Plutonium Atoms: Reaction Mechanisms and Ab Initio Molecular Dynamics Study
Authors: Li Peng , Niu Wenxia , Gao Tao , Wang Hongyan 
Published: July 2014

AbstractA thorough description of the reaction mechanisms, taking into account different possible spin states, offers insights into the gas‐phase reaction of plutonium atoms with water. Two possible reactions (isomerization and dehydrogenation) are presented. These reactions are found to be exothermic, with the best thermochemical conditions observed for the dehydrogenation reaction at around 23.5 kcal mol−1. The nature of the chemical‐bonding evolution along the reaction pathways are investigated by employing various methods including electron localization function, atoms in molecules, and Mayer bond order. Total, partial, and overlap population density of state diagrams and analyses are also presented. Reaction rates at elevated temperatures (T=298–2 000 K) are calculated by using variational transition‐state theory with one‐dimensional tunneling effects. In dynamics simulations, only the dehydrogenation reaction is observed, and found to be in good agreement with experimental values.
Biological Production of Muconic Acid via a Prokaryotic 2,3‐Dihydroxybenzoic Acid Decarboxylase
Authors: Sun Xinxiao , Lin Yuheng , Yuan Qipeng , Yan Yajun 
Published: July 2014

AbstractNon‐oxidative decarboxylases belong to a unique enzyme family that does not require any cofactors. Here we report the characterization of a 2,3‐dihydroxybenzoic acid (2,3‐DHBA) decarboxylase (BDC) from Klebsiella pneumoniae and explore its application on the production of muconic acid. The enzyme properties were systematically studied, including the optimal temperature and pH, kinetic parameters, and substrate specificity. On this basis, we designed an artificial pathway for muconic acid production by connecting 2,3‐DHBA biosynthesis with its degradation pathway. Over‐expression of entCBA and the key enzymes in the shikimate pathway led to the production of 900 mg L−1 of 2,3‐DHBA. Further, expression of the BDC coupled with catechol 1,2‐dioxygenase achieved the conversion of 2,3‐DHBA into muconic acid. Finally, assembly of the total pathway resulted in the de novo production of muconic acid up to 480 mg L−1.
Melatonin administered during the fetal stage affects circadian clock in the suprachiasmatic nucleus but not in the liver
Authors: Houdek Pavel , Polidarová Lenka , Nováková Marta , Matějů Kristýna , Kubík Štěpán , Sumová Alena 
Published: July 2014

ABSTRACTThe mammalian circadian system develops gradually during ontogenesis, and after birth, the system is already set to a phase of the mothers. The role of maternal melatonin in the entrainment of fetal circadian clocks has been suggested, but direct evidence is lacking. In our study, intact or pinealectomized pregnant rats were exposed to constant light (LL) throughout pregnancy to suppress the endogenous melatonin and behavioral rhythms. During the last 5 days of gestation, the rats were injected with melatonin or vehicle or were left untreated. After delivery, daily expression profiles of c‐fos and Avp in the suprachiasmatic nuclei (SCN), and Per1, Per2, Rev‐erbα, and Bmal1 in the liver were measured in 1‐day‐old pups. Due to the LL exposure, no gene expression rhythms were detected in the SCN of untreated pregnant rats or in the SCN and liver of the pups. The administration of melatonin to pregnant rats entrained the pups' gene expression profiles in the SCN, but not in the liver. Melatonin did not affect the maternal behavior during pregnancy. Vehicle injections also synchronized the gene expression in the SCN but not in the liver. Melatonin and vehicle entrained the gene expression profiles to different phases, demonstrating that the effect of melatonin was apparently not due to the treatment procedure per se. The data demonstrate that in pregnant rats with suppressed endogenous melatonin levels, pharmacological doses of melatonin affect the fetal clock in the SCN but not in the liver. © 2014 Wiley Periodicals, Inc. Develop Neurobiol 75: 131–144, 2015
Left atrial volume predicts abnormal exercise left ventricular filling pressure
Authors: Hammoudi Nadjib , Achkar Marc , Laveau Florent , Boubrit Lila , Djebbar Morad , Allali Yann , Komajda Michel , Isnard Richard 
Published: July 2014

AimsLatent heart failure at rest can be observed in a number of patients upon exercise. Considering left atrial (LA) remodelling as the reflection of the cumulative effects of the LV filling pressure (FP) over time, our aim was to investigate whether the LA volume would predict abnormal exercise LVFP.Methods and resultsNinety patients (58.6 ± 10.8 years, 74 men) underwent exercise echocardiography. The LA maximal volume was measured by the Simpson method and indexed to body surface area. LVFP was assessed by the ratio between early peak diastolic velocities of mitral inflow and the septal annular mitral plane (E/e′). Exercise E/e′ >13 was used as a threshold to define abnormal LVFP. Indexed LA volume was correlated with E/e′ at rest (r = 0.37, P = 0.003), but the correlation was better with exercise E/e′ (r = 0.54, P < 0.0001). In multivariate analysis, age, LV end‐diastolic volume index, LVEF, and exercise E/e′ were the independent determinants of LA volume index (R2 = 0.47, P < 0.0001). Eleven patients had exercise E/e′ >13; compared with the rest of the population, these patients were older and achieved a milder effort. LA volume index >33 mL/m2 predicted an abnormal exercise LVFP with a 91% sensitivity and a 78% specificity. None of the patients with an LA volume index <26 mL/m2 (n = 31, 34%) had an exercise E/e′ >13.ConclusionExercise LVFP is a determinant of LA size. LA volume index seems to be helpful for predicting abnormal exercise LVFP. The potential use of LA remodelling to identify the patients benefitting most from exercise echocardiography should be investigated in larger studies.
Influence of systolic blood pressure on clinical outcomes in elderly heart failure patients treated with nebivolol: data from the SENIORS trial
Authors: Montero‐Perez‐Barquero Manuel , Flather Marcus , Roughton Michael , Coats Andrew , Böhm Michael , Van Veldhuisen Dirk J. , Babalis Daphne , Solal Alain Cohen , Manzano Luis 
Published: July 2014

AimsThere is limited information about the effects of beta‐blockers in heart failure (HF) stratified by blood pressure, especially in the elderly and those with preserved EF. We evaluate the effects of nebivolol on outcomes in elderly patients with HF stratified by baseline systolic blood pressure (SBP) and EF.Methods and resultsThe SENIORS trial evaluated the effects of nebivolol and enrolled 2128 patients ≥70 years of age with HF. Patients were divided into three baseline pre‐treatment SBP categories (<110, 110–130, and >130 mmHg). In addition, we evaluated the influence of SBP (≤130 and >130 mmHg) on patients with LVEF <40% vs. ≥40%. Low baseline SBP was associated with worse clinical outcomes irrespective of treatment group, both in patients with reduced EF and in those with preserved EF. Nebivolol had similar benefits irrespective of baseline SBP: the hazard ratio (HR) for primary outcome of all‐cause mortality or cardiovascular hospitalization in the three SBP categories for nebivolol vs. placebo was 0.85 [95% confidence interval (CI) 0.50–1.45], 0.79 (95% CI 0.61–1.01), and 0.88 (95% CI 0.72–1.07), respectively (P for interaction = 0.61). Similar results were obtained for the secondary endpoint of all‐cause mortality. There was no significant interaction for the effects of nebivolol by baseline SBP stratified by LVEF.ConclusionsElderly HF patients with lower SBP have a worse outcome than those with higher SBP, but nebivolol appears to be safe and well tolerated, with similar benefits on the composite outcome of death or cardiovascular hospital admission irrespective of baseline SBP and LVEF.
Recent Developments in the Chemistry of gem‐Halonitro Compounds
Authors: Soengas Raquel G. , Acúrcio Rita C. , Silva Artur M. S. 
Published: July 2014

Abstractgem‐Halonitro compounds are valuable synthetic intermediates of growing chemical interest that have been known for many years. Initially, the interest in gem‐halonitro compounds lay in their biological activity, whereas their chemistry remained quite underdeveloped. In the past few years, however, interest in the chemistry of gem‐halonitro compounds has grown exponentially, sparked by some recent investigations into the reactivity of the gem‐halonitro moiety. Nowadays, gem‐halonitro compounds are recognized as powerful chemical tools on account of their usefulness as synthetic intermediates. This review highlights recent synthetic strategies based on gem‐halonitro compounds and provides an overview of their usefulness in organic chemistry.
Chiral Room Temperature Ionic Liquids as Enantioselective Promoters for the Asymmetric Aldol Reaction
Authors: González Laura , Escorihuela Jorge , Altava Belén , Burguete M. Isabel , Luis Santiago V. 
Published: July 2014

AbstractChiral ionic liquids derived from natural amino acids are shown to be green and efficient media for direct asymmetric aldol reactions at room temperature catalyzed by (S)‐proline. The corresponding aldol products were obtained with moderate to good enantioselectivities. A transfer of chirality from the chiral reaction media has been observed as well as the participation of match/mismatch interactions of the chiral medium with both enantiomers of proline. Moreover, these catalytic systems were easily recovered by simple filtration, and studies on their reuse have demonstrated that recycling is possible for at least four runs with only a slight reduction in activity.
N‐Acyl‐N‐tosylhydrazine as a Synthon To Construct Tetrasubstituted Carbon Centers Possessing a Nitrogen Group
Authors: Namba Kosuke , Shobo Yoshihiro , Fujimoto Kazuki , Shoji Isamu , Yoshida Masahiro , Tanino Keiji 
Published: July 2014

AbstractNew halohydrazidation and hydrazidopalladation reactions were developed that use the synthon N‐acyl‐N‐tosylhydrazine. The intramolecular bromohydrazidation reactions of β,γ‐unsaturated N‐acyl‐N‐tosylhydrazines readily afforded pyrazolidinone ring systems that contained a tetrasubstituted carbon center, and the primary amine of the N‐acyl‐N‐tosylhydrazine was shown to be a soft nucleophile. The similar bromohydrazidation reaction of γ,δ‐unsaturated N‐acyl‐N‐tosylhydrazine resulted in O‐cyclization to give a lactone ring instead of N‐cyclization to give a hydropyridazine ring system; however, the intramolecular hydrazidopalladation reaction predominantly afforded a hydropyridazine ring. The established catalytic hydrazidopalladation reaction was applicable to several multisubstituted alkenes to construct a tetrasubstituted carbon center possessing a nitrogen group.
Electrochemical Determination of Phenolic Acids at a Zn/Al Layered Double Hydroxide Film Modified Glassy Carbon Electrode
Authors: Kahl Michael , Golden Teresa D. 
Published: July 2014

AbstractA stable sensor for the determination of gallic acid (GA) and caffeic acid (CA) was fabricated by electrodeposition of Zn‐Al‐NO3 layered double hydroxide film on a glassy carbon electrode (LDHf/GCE). A sensitive electrochemical method was achieved for the determination of GA and CA in a phosphate buffer solution (pH 3). The differential pulse voltammetry response of the LDHf/GCE to GA has a linear concentration range from 4 µM to 600 µM with a correlation coefficient of 0.9985 and the calculated detection limit of 1.6 µM at a signal‐to‐noise ratio of 3. The differential pulse voltammetry response of the LDHf/GCE to CA has a linear concentration range from 7 µM to 180 µM with a correlation coefficient of 0.9969 and the calculated detection limit of 2.6 µM at a signal‐to‐noise ratio of 3. The constructed sensor was applied to the determination of GA in commercial green tea samples.
Hydraulic “Fracking”: Are surface water impacts an ecological concern?
Authors: Burton G. Allen , Basu Niladri , Ellis Brian R. , Kapo Katherine E. , Entrekin Sally , Nadelhoffer Knute 
Published: July 2014

Abstract

Use of high-volume hydraulic fracturing (HVHF) in unconventional reservoirs to recover previously inaccessible oil and natural gas is rapidly expanding in North America and elsewhere. Although hydraulic fracturing has been practiced for decades, the advent of more technologically advanced horizontal drilling coupled with improved slickwater chemical formulations has allowed extensive natural gas and oil deposits to be recovered from shale formations. Millions of liters of local groundwaters are utilized to generate extensive fracture networks within these low-permeability reservoirs, allowing extraction of the trapped hydrocarbons. Although the technology is relatively standardized, the geographies and related policies and regulations guiding these operations vary markedly. Some ecosystems are more at risk from these operations than others because of either their sensitivities or the manner in which the HVHF operations are conducted. Generally, the closer geographical proximity of the susceptible ecosystem to a drilling site or a location of related industrial processes, the higher the risk of that ecosystem being impacted by the operation. The associated construction of roads, power grids, pipelines, well pads, and water-extraction systems along with increased truck traffic are common to virtually all HVHF operations. These operations may result in increased erosion and sedimentation, increased risk to aquatic ecosystems from chemical spills or runoff, habitat fragmentation, loss of stream riparian zones, altered biogeochemical cycling, and reduction of available surface and hyporheic water volumes because of withdrawal-induced lowering of local groundwater levels. The potential risks to surface waters from HVHF operations are similar in many ways to those resulting from agriculture, silviculture, mining, and urban development. Indeed, groundwater extraction associated with agriculture is perhaps a larger concern in the long term in some regions. Understanding the ecological impacts of these anthropogenic activities provides useful information for evaluations of potential HVHF hazards. Geographic information system–based modeling combined with strategic site monitoring has provided insights into the relative importance of these and other ecoregion and land-use factors in discerning potential HVHF impacts. Recent findings suggest that proper siting and operational controls along with strategic monitoring can reduce the potential for risks to aquatic ecosystems. Nevertheless, inadequate data exist to predict ecological risk at this time. The authors suggest considering the plausibility of surface water hazards associated with the various HVHF operations in terms of the ecological context and in the context of relevant anthropogenic activities. Environ Toxicol Chem 2014;33:1679–1689. © 2014 SETAC
Are flat‐field snow depth measurements representative? A comparison of selected index sites with areal snow depth measurements at the small catchment scale
Authors: Grünewald Thomas , Lehning Michael 
Published: July 2014

AbstractSingle or a limited number of point observations, such as from index stations, are commonly assumed to be representative for the snow cover of larger areas in many applications. This study presents a systematic investigation of the relationship between point observations and areal mean snow depths ranging from the scale of tens of metres to entire catchments. We analyse aerial snow depth information from four mountain regions in the European Alps, one in the Spanish Pyrenees and one in the Canadian Rocky Mountains, obtained from airborne laser scanning surveys. This rich data set allowed to compare point values with snow cover statistics, reflecting the real snow depth distribution of the investigation areas. We present two contrasting approaches in order to assess the representativeness of typical flat‐field snow depth measurements. In the first approach, we define potential index stations based on topographic characteristics as commonly applied for snow cover monitoring stations. The point observations of these index stations are then compared with the mean values in their vicinities. We show that most of the index stations strongly overestimate the snow depth of the catchment and of their surrounding area at distances of several hundreds of metres. Results confirm the expectation that the larger the support area, the smaller the difference to the mean of the complete catchment. The second approach was to analyse topographic characteristics of all cells with snow depths that deviated less than 10% from the catchment mean. It appears that these representative cells are rather randomly distributed and cannot be identified a priori. In summary, our results show large potential biases of index stations with respect to snow distribution and therefore also snow water equivalent. Copyright © 2014 John Wiley & Sons, Ltd.