bluuebunny/crossref_metadata_2025_split huggingface dataset:
Binuclear trans‐Bis(β‐iminoaryloxy)palladium(II) Complexes Doubly Linked with Pentamethylene Spacers: Structure‐Dependent Flapping Motion and Heterochiral Association Behavior of the Clothespin‐Shaped Molecules
Authors: Naito Masaya , Souda Hiroyuki , Koori Hiroshi , Komiya Naruyoshi , Naota Takeshi 
Published: April 2014

AbstractThe synthesis, structure, and solution‐state behavior of clothespin‐shaped binuclear trans‐bis(β‐iminoaryloxy)palladium(II) complexes doubly linked with pentamethylene spacers are described. Achiral syn and racemic anti isomers of complexes 1–3 were prepared by treating Pd(OAc)2 with the corresponding N,N′‐bis(β‐hydroxyarylmethylene)‐1,5‐pentanediamine and then subjecting the mixture to chromatographic separation. Optically pure (100 % ee) complexes, (+)‐anti‐1, (+)‐anti‐2, and (+)‐anti‐3, were obtained from the racemic mixture by employing a preparative HPLC system with a chiral column. The trans coordination and clothespin‐shaped structures with syn and anti conformations of these complexes have been unequivocally established by X‐ray diffraction studies. 1H NMR analysis showed that (±)‐anti‐1, (±)‐anti‐2, syn‐2, and (±)‐anti‐3 display a flapping motion by consecutive stacking association/dissociation between cofacial coordination planes in [D8]toluene, whereas syn‐1 and syn‐3 are static under the same conditions. The activation parameters for the flapping motion (ΔH≠ and ΔS≠) were determined from variable‐temperature NMR analyses as 50.4 kJ mol−1 and 60.1 J mol−1 K−1 for (±)‐anti‐1, 31.0 kJ mol−1 and −22.7 J mol−1 K−1 for (±)‐anti‐2, 29.6 kJ mol−1 and −57.7 J mol−1 K−1 for syn‐2, and 35.0 kJ mol−1 and 0.5 J mol−1 K−1 for (±)‐anti‐3, respectively. The molecular structure and kinetic parameters demonstrate that all of the anti complexes flap with a twisting motion in [D8]toluene, although (±)‐anti‐1 bearing dilated Z‐shaped blades moves more dynamically than I‐shaped (±)‐anti‐2 or the smaller (±)‐anti‐3. Highly symmetrical syn‐2 displays a much more static flapping motion, that is, in a see‐saw‐like manner. In CDCl3, (±)‐anti‐1 exhibits an extraordinary upfield shift of the 1H NMR signals with increasing concentration, whereas solutions of (+)‐anti‐1 and the other syn/anti analogues 2 and 3 exhibit negligible or slight changes in the chemical shifts under the same conditions, which indicates that anti‐1 undergoes a specific heterochiral association in the solution state. Equilibrium constants for the dimerizations of (±)‐ and (+)‐anti‐1 in CDCl3 at 293 K were estimated by curve‐fitting analysis of the 1H NMR chemical shift dependences on concentration as 26 M−1 [KD(racemic)] and 3.2 M−1 [KD(homo)], respectively. The heterochiral association constant [KD(hetero)] was estimated as 98 M−1, based on the relationship KD(racemic)=1/2 KD(homo)+1/4 KD(hetero). An inward stacking motif of interpenetrative dimer association is postulated as the mechanistic rationale for this rare case of heterochiral association.
DFT Simulations of Water Adsorption and Activation on Low‐Index α‐Ga2O3 Surfaces
Authors: Zhou Xin , Hensen Emiel J. M. , van Santen Rutger A. , Li Can 
Published: April 2014

AbstractDensity functional theory (DFT) calculations are used to explore water adsorption and activation on different α‐Ga2O3 surfaces, namely (001), (100), (110), and (012). The geometries and binding energies of molecular and dissociative adsorption are studied as a function of coverage. The simulations reveal that dissociative water adsorption on all the studied low‐index surfaces are thermodynamically favorable. Analysis of surface energies suggests that the most preferentially exposed surface is (012). The contribution of surface relaxation to the respective surface energies is significant. Calculations of electron local density of states indicate that the electron‐energy band gaps for the four investigated surfaces appears to be less related to the difference in coordinative unsaturation of the surface atoms, but rather to changes in the ionicity of the surface chemical bonds. The electrochemical computation is used to investigate the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) on α‐Ga2O3 surfaces. Our results indicate that the (100) and (110) surfaces, which have low stability, are the most favorable ones for HER and OER, respectively.
A Systematic Study of Peripherally Multiple Aromatic Ester‐Functionalized Poly(benzyl ether) Dendrons for the Fabrication of Organogels: Structure–Property Relationships and Thixotropic Property
Authors: Feng Yu , Liu Zhi‐Xiong , Chen Hui , Yan Zhi‐Chao , He Yan‐Mei , Liu Chen‐Yang , Fan Qing‐Hua 
Published: April 2014

AbstractA new class of peripherally multiple aromatic ester‐functionalized poly(benzyl ether) dendrons and/or dendrimers with different focal point substituents, surface groups, interior structures, as well as different generations have been synthesized and their structure–property relationships with respect to their gelation ability have been investigated systematically. Most of these dendrons are able to gel organic solvents over a wide polarity range. Evident dendritic effects were observed not only in gelation capability but also in thermotropic, morphological, and rheological characterizations. It was disclosed that subtle changes in peripheral ester functionalities and interior dendritic structures affected the gelation behavior of the dendrons significantly. Among all the dendrons studied, the second‐ and third‐generation dendrons G0G2‐Me and G0G3‐Me with dimethyl isophthalates (DMIP) as peripheral groups exhibited the best capability in gelation, and stable gels were formed in more than 22 aromatic and polar organic solvents. The lowest critical gelation concentration (CGC) reached 2.0 mg mL−1, indicating that approximately 1.35×104 solvent molecules could be entrapped by one dendritic molecule. Further study on driving forces in gel formation was carried out by using a combination of single‐crystal/powder X‐ray diffraction (XRD) analysis and concentration‐dependent (CD)/temperature‐dependent (TD) 1H NMR spectroscopy. The results obtained from these experiments revealed that the multiple π–π stacking of extended π‐systems due to the peripheral DMIP rings, cooperatively assisted by non‐conventional hydrogen‐bonding, is the key contributor in the formation of the highly ordered supramolecular and fibrillar network. In addition, these dendritic organogels exhibited unexpected thixotropic‐responsive properties, which make them promising candidates with potential applications in the field of intelligent soft materials.
Solvothermal Transformation of a Calcium Oleate Precursor into Large‐Sized Highly Ordered Arrays of Ultralong Hydroxyapatite Microtubes
Authors: Lu Bing‐Qiang , Zhu Ying‐Jie , Chen Feng , Qi Chao , Zhao Xin‐Yu , Zhao Jing 
Published: April 2014

AbstractHydroxyapatite (HAP), a well‐known member of the calcium phosphate family, is the major inorganic component of bones and teeth in vertebrates. The highly ordered arrays of HAP structures are of great significance for hard tissue repair and for understanding the formation mechanisms of bones and teeth. However, the synthesis of highly ordered HAP structure arrays remains a great challenge. In this work, inspired by the ordered structure of tooth enamel, we have successfully synthesized three‐dimensional bulk materials with large sizes (millimeter scale) that are made of highly ordered arrays of ultralong HAP microtubes (HOAUHMs) by solvothermal transformation of calcium oleate precursor. The core–shell‐structured oblate sphere consists of a core that is composed of HAP nanorods and a shell that consists of highly ordered HAP microtube arrays. The prepared HOAUHMs are large: 6.0 mm in diameter and up to 1.4 mm in thickness. With increasing solvothermal reaction time, the HOAUHMs grow larger; the microtubes become more uniform and more ordered. This work provides a new synthetic method for synthesizing highly ordered arrays of uniform HAP ultralong microtubes that are promising for biomedical applications.
Nanostructured Graphene/TiO2 Hybrids as High‐Performance Anodes for Microbial Fuel Cells
Authors: Zhao Cui‐e , Wang Wen‐Jing , Sun Dong , Wang Xin , Zhang Jian‐Rong , Zhu Jun‐Jie 
Published: April 2014

AbstractA new nanostructured graphene/TiO2 (G/TiO2) hybrid was synthesized by a facile microwave‐assisted solvothermal process in which amorphous TiO2 was assembled on graphene in situ. The resulting G/TiO2 hybrids were characterized by XRD, SEM, TEM, Raman spectroscopy, and N2 adsorption/desorption analysis. The electrochemical properties of the hybrids as anode materials for Shewanella‐inoculated microbial fuel cells (MFCs) were studied for the first time, and they proved to be effective in improving MFC performance. The significantly improved bacterial attachment and extracellular electron‐transfer efficiency could be attributed to the high specific surface area, active groups, large pore volume, and excellent conductivity of the nanostructured G/TiO2 hybrid, and this suggests that it could be a promising candidate for high‐performance MFCs.
Multicomponent, Flow Diazotization/Mizoroki–Heck Coupling Protocol: Dispelling Myths about Working with Diazonium Salts
Authors: Nalivela Kumara S. , Tilley Michael , McGuire Michael A. , Organ Michael G. 
Published: April 2014

AbstractA single pass flow diazotization/Mizoroki–Heck protocol has been developed for the production of cinnimoyl and styryl products. The factors that govern aryl diazonium salt stability have been examined in detail leading to the development of a MeOH/DMF co‐solvent system in which the diazonium salts can be generated in the presence of all other reaction components and then coupled selectively to give the desired products. Finally the key role of the reaction quench for flow reactions has been demonstrated.
Photoinduced Intercalation and Coordination of a Dirhodium Complex to DNA: Dual DNA Binding
Authors: Palmer Alycia M. , Burya Scott J. , Gallucci Judith C. , Turro Claudia 
Published: April 2014

AbstractTwo new complexes, cis‐H,H‐[Rh2(OCCH3NH)2(LL)(CH3CN)2]2+, where LL=bpy (2, bpy=2,2′‐bipyridine) and dppz (3, dppz=dipyrido[3,2‐a:2′,3′‐c]phenazine), were prepared from the reaction of cis‐H,H‐[Rh2(OCCH3NH)2(CH3CN)6]2+ (1) with the corresponding bidentate ligand. The bpy and dppz ligands chelate to the same rhodium atom and are positioned trans to the amidato N atoms, as determined by the single crystal X‐ray structure of 2. Irradiation of 2 and 3 with visible light in water results in the exchange of one CH3CNeq ligand for an H2O molecule with quantum yields, Φ400, of 0.040 and 0.044, respectively (λirr=400 nm). The identities of the photoproducts of 2 and 3 were determined to be cis‐H,H‐[Rh2(OCCH3NH)2(L)(H2O)(CH3CN)]2+, where L is bpy (4) and dppz (5), respectively. Mobility shift assays show that 4 crosslinks double‐stranded DNA, and ESI‐MS experiments indicate that both 4 and 5 form covalent adducts with single‐stranded DNA. In addition, relative viscosity and 2D NMR experiments show that the dppz ligand of 5 also intercalates into DNA upon irradiation, making 3 a dual‐binding agent that both intercalates and covalently binds to DNA upon the absorption of visible light.
Does Excited‐State Proton‐Transfer Reaction Contribute to the Emission Behaviour of 4‐Aminophthalimide in Aqueous Media?
Authors: Khara Dinesh Chandra , Banerjee Sanghamitra , Samanta Anunay 
Published: April 2014

Abstract4‐Aminophthalimide (AP) is an extensively used molecule both for fundamental studies and applications primarily due to its highly solvent‐sensitive fluorescence properties. The fluorescence spectrum of AP in aqueous media was recently shown to be dependent on the excitation wavelength. A time‐dependent blue shift of its emission spectrum is also reported. On the basis of these findings, the excited‐state solvent‐mediated proton‐transfer reaction of the molecule, which was proposed once but discarded at a later stage, is reintroduced. We report on the fluorescence behaviour of AP and its imide‐H protected derivative, N‐BuAP, to prove that a solvent‐assisted excited‐state keto–enol transformation does not contribute to the steady‐state and time‐resolved emission behaviour of AP in aqueous media. Our results also reveal that the fluorescence of AP in aqueous media arises from two distinct hydrogen‐bonded species. The deuterium isotope effect on the fluorescence quantum yield and lifetime of AP, which was thought to be a reflection of the excited‐state proton‐transfer reaction in the system, is explained by considering the difference in the influence of H2O and D2O on the nonradiative rates and ground‐state exchange of the proton with the solvent.
Reversible Chemical Reactions for Single‐Color Multiplexing Microscopy
Authors: Brox Dominik , Schwering Michael , Engelhardt Johann , Herten Dirk‐Peter 
Published: April 2014

AbstractRecent developments in biology demand an increasing number of simultaneously imaged structures with standard fluorescence microscopy. However, the number of multiplexed channels is limited for most multiplexing modalities, such as spectral multiplexing or fluorescence‐lifetime imaging. We propose extending the number of imaging channels by using chemical reactions, controlling the emissive state of fluorescent dyes. As proof of concept, we reversibly switch a fluorescent copper sensor to enable successive imaging of two different structures in the same spectral channel. We also show that this chemical multiplexing is orthogonal to existing methods. By using two different dyes, we combine chemical with spectral multiplexing for the simultaneous imaging of four different structures with only two spectrally different channels. We characterize and discuss the approach and provide perspectives for extending imaging modalities in stimulated emission depletion microscopy, for which spectral multiplexing is technically demanding.
Adolescent MDMA exposure diminishes the physiological and neurotoxic consequences of an MDMA binge in female rats
Authors: Piper Brian J. , Henderson Christina S. , Meyer Jerrold S. 
Published: April 2014

AbstractIntermittent MDMA pretreatment blocked the reductions in serotonin transporter (SERT) binding induced by an MDMA binge in a prior study in adolescent male rats. The objective of this investigation was to determine if the physiological, behavioral, and neurochemical responses to MDMA are sexually dimorphic. Female Sprague–Dawley rats received MDMA (10 mg/kg × 2) or Saline on every fifth day from postnatal day (PD) 35–60 and an MDMA binge (5 mg/kg × 4) on PD 67. The MDMA binge induced a pronounced temperature dysregulation in MDMA‐naïve, but not MDMA‐pretreated, groups. Similarly, MDMA‐pretreated animals were resistant to the binge‐induced SERT reductions, especially in the hippocampus. Motor activity at PD 68 was not reduced by the binge, unlike the responses found in males. These results show that female rats differ from males in their responses to an MDMA binge but are similar with respect to preconditioning from prior MDMA exposure. © 2013 Wiley Periodicals, Inc. Dev Psychobiol 56: 924–934, 2014.
Cooking losses, lipid oxidation and formation of volatile compounds in foal meat as affected by cooking procedure
Authors: Lorenzo José M. , Domínguez Rubén 
Published: April 2014

ABSTRACTThe present study deals with the effect of four different cooking techniques (roasting, grilling, microwave baking and frying with olive oil) on cooking losses, lipid oxidation (by thiobarbituric acid reactive substances (TBARS) measurement) and formation of volatile compounds (using solid‐phase microextraction (SPME) and gas chromatography combined with mass spectrometry (GC–MS)) of foal meat. Statistical analysis displayed significant (P < 0.001) differences on cooking losses by thermal treatment, being lower in foal steaks cooked by grilling (21.1%) and higher in those cooked by microwaving (35.2%). As expected, all the cooking methods increased the TBARS index, because high temperatures during cooking seem to cause an increase of the lipid oxidation in foal steaks, being higher in roasted and microwaved foal meat, followed by grilled and fried cooking. Thermal treatments led to an increase in total volatile compounds (ranging from 734.6 to 955.1 area units (AU) × 106/g dry matter) compared with raw steaks (301.3 AU × 106/g dry matter). As cooking temperature increased, an increase in the formation of volatile compounds and lipid oxidation was observed. The major volatile compounds were aldehydes in cooked samples, whereas in raw steaks they were esters. This indicates that the compounds produced by lipid oxidation have a great influence on the flavour of the cooked meat. Copyright © 2014 John Wiley & Sons, Ltd.
Transcranial electrical stimulation modifies the neuronal response to psychosocial stress exposure
Authors: Antal Andrea , Fischer Thomas , Saiote Catarina , Miller Robert , Chaieb Leila , Wang Danny J.J. , Plessow Franziska , Paulus Walter , Kirschbaum Clemens 
Published: April 2014

AbstractStress is a constant characteristic of everyday life in our society, playing a role in triggering several chronic disorders. Therefore, there is an ongoing need to develop new methods in order to manage stress reactions. The regulatory function of right medial‐prefrontal cortex (mPFC) is frequently reported by imaging studies during psychosocial stress situations. Here, we examined the effects of inhibitory and excitatory preconditioning stimulation via cathodal and anodal transcranial direct current stimulation (tDCS) on psychosocial stress related behavioral indicators and physiological factors, including the cortisol level in the saliva and changes in brain perfusion. Twenty minutes real or sham tDCS was applied over the right mPFC of healthy subjects before the performance of the Trier Social Stress Test (TSST). Regional cerebral blood flow (rCBF) was measured during stimulation and after TSST, using pseudo‐continuous arterial spin labeling (pCASL). Comparing the effect of the different stimulation conditions, during anodal stimulation we found higher rCBF in the right mPFC, compared to the sham and in the right amygdala, superior PFC compared to the cathodal condition. Salivary cortisol levels showed a decrease in the anodal and increase in cathodal groups after completion of the TSST. The behavioral stress indicators indicated the increase of stress level, however, did not show any significant differences among groups. In this study we provide the first insights into the neuronal mechanisms mediating psychosocial stress responses by prefrontal tDCS. Hum Brain Mapp 35:3750–3759, 2014. © 2013 Wiley Periodicals, Inc.
Informal Care and Caregiver's Health
Authors: Do Young Kyung , Norton Edward C. , Stearns Sally C. , Van Houtven Courtney Harold 
Published: April 2014

AbstractThis study aims to measure the causal effect of informal caregiving on the health and health care use of women who are caregivers, using instrumental variables. We use data from South Korea, where daughters and daughters‐in‐law are the prevalent source of caregivers for frail elderly parents and parents‐in‐law. A key insight of our instrumental variable approach is that having a parent‐in‐law with functional limitations increases the probability of providing informal care to that parent‐in‐law, but a parent‐in‐law's functional limitation does not directly affect the daughter‐in‐law's health. We compare results for the daughter‐in‐law and daughter samples to check the assumption of the excludability of the instruments for the daughter sample. Our results show that providing informal care has significant adverse effects along multiple dimensions of health for daughter‐in‐law and daughter caregivers in South Korea. Copyright © 2013 John Wiley & Sons, Ltd.
The hippocampus, medial prefrontal cortex, and selective memory retrieval: Evidence from a rodent model of the retrieval‐induced forgetting effect
Authors: Wu Jade Q. , Peters Greg J. , Rittner Pedro , Cleland Thomas A. , Smith David M. 
Published: April 2014

ABSTRACTInhibition is an important component of many cognitive functions, including memory. For example, the retrieval‐induced forgetting (RIF) effect occurs when extra practice with some items from a study list inhibits the retrieval of the nonpracticed items relative to a baseline condition that does not involve extra practice. Although counterintuitive, the RIF phenomenon may be important for resolving interference by inhibiting potentially competing retrieval targets. Neuroimaging studies suggest that the hippocampus and prefrontal cortex are involved in the RIF effect, but controlled lesion studies have not yet been performed. We developed a rodent model of the RIF training procedure and trained control rats and rats with temporary inactivation of the hippocampus or medial prefrontal cortex (mPFC). Rats were trained on a list of odor cues, presented in cups of digging medium with a buried reward, followed by additional practice trials with a subset of the cues. We then tested the rats' memories for the cues and their association with reward by presenting them with unbaited cups containing the test odorants and measuring how long they persisted in digging. Control rats exhibited a robust RIF effect in which memory for the nonpracticed odors was significantly inhibited. Thus, extra practice with some odor cues inhibited memory for the others, relative to a baseline condition that involved an identical amount of training. Inactivation of either the hippocampus or the mPFC blocked the RIF effect. We also constructed a computational model of a representational learning circuit to simulate the RIF effect. We show in this model that “sideband suppression” of similar memory representations can reproduce the RIF effect and that alteration of the suppression parameters and learning rate can reproduce the lesion effects seen in our rats. Our results suggest that the RIF effect is widespread and that inhibitory processes are an important feature of memory function. © 2014 Wiley Periodicals, Inc.
Reproducibility of thoracic and abdominal aortic wall measurements with three‐dimensional, variable flip angle (SPACE) MRI
Authors: Mihai Georgeta , Varghese Juliet , Lu Bo , Zhu Hong , Simonetti Orlando P. , Rajagopalan Sanjay 
Published: April 2014

PurposeTo evaluate the reproducibility and repeatability of high‐resolution, isotropic thoracic and abdominal aortic wall measurements, and determine the implications they have on the number of subjects necessary for future clinical trials.Materials and MethodsUsing a T1‐weighted three‐dimensional MRI SPACE sequence, we evaluated the interobserver, intraobserver, and scan–rescan variability of isotropic thoracic and abdominal aortic wall measurements in 15 cardiovascular diseased patients and 6 normal volunteers. Main outcome analyses were intracorrelation coefficient (ICC), mean relative error (mRE), and sample size calculation at 80% power to be used to compare placebo group and treatment group means in future two‐arm randomized clinical trials.ResultsExcellent reliability, ICC > 0.8 (P < 0.001) and small mRE < 10% were demonstrated for the interobserver, intraobserver, and scan–rescan variability for all investigated measures: lumen area (LA), outer wall area (OWA), wall area (VWA), total wall volume (TWV), and percentage wall volume (%WV). Sample size calculation revealed slightly different sample size per treatment arm for thoracic and abdominal aorta segments (maximum number of subjects: 352 subjects for thoracic segment versus 421 subjects for abdominal segment for LA at 5% difference, and minimum of 3 thoracic versus 4 abdominal subjects needed for %WV evaluation at 25% difference).ConclusionOur study demonstrates the reproducibility and repeatability of SPACE aortic plaque measurements, and gives insight into the number of subjects needed for the design of therapeutic studies in aortic atherosclerosis. J. Magn. Reson. Imaging 2015;41:202–212. © 2013 Wiley Periodicals, Inc.