bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface Tectonics of Nanoporous Networks of Melamine‐Capped Molecular Building Blocks formed through Interface Schiff‐Base Reactions
Authors: Liu Xuan‐He , Wang Dong , Wan Li‐Jun
Published: July 2013

Control over the assembly of molecules on a surface is of great importance for the fabrication of molecule‐based miniature devices. Melamine (MA) and molecules with terminal MA units are promising candidates for supramolecular interfacial packing patterning, owing to their multiple hydrogen‐bonding sites. Herein, we report the formation of self‐assembled structures of MA‐capped molecules through a simple on‐surface synthetic route. MA terminal groups were successfully fabricated onto rigid molecular cores with 2‐fold and 3‐fold symmetry through interfacial Schiff‐base reactions between MA and aldehyde groups. Sub‐molecular scanning tunneling microscopy (STM) imaging of the resultant adlayer revealed the formation of nanoporous networks. Detailed structural analysis indicated that strong hydrogen‐bonding interactions between the MA groups persistently drove the formation of nanoporous networks. Herein, we demonstrate that functional groups with strong hydrogen‐bond‐formation ability are promising building blocks for the guided assembly of nanoporous networks and other hierarchical 2D assemblies.
Design of Fixed Structure Pid Controller for Nonlinear System with Saturation
Authors: Fang Bin
Published: July 2013

An approach is presented to design a PID controller for a given plant with saturation. Based on the describing function models of saturation and the method of determining the sets of stabilizing a PID controller for a linear plant with time delay or one that is delay free, the new equivalent inverse Nyquist plots are given for different sinusoidal input amplitudes of saturation. The PID controller parameters are selected from intersecting sets of stabilizing PID parameter regions for different input amplitudes. The controller can effectively mitigate the saturation effect. For an open‐loop unstable plant, a prefilter is added on the reference input. Within the proposed framework, this approach can improve the stability of the system and reduce the degree of saturation. The simulation examples demonstrate the validity of the proposed approach.
Multivariate dynamic regression: modeling and forecasting for intraday electricity load
Authors: Migon Helio S. , Alves Larissa C.
Published: July 2013

This paper introduces electricity load curve models for short‐term forecasting purposes. A broad class of multivariate dynamic regression models is proposed to model hourly electricity load. Alternative forecasting models, special cases of our general model, include separate time series regressions for each hour and week day. All the models developed include components that represent trends, seasons at different levels (yearly, weekly, etc.), dummies to take into account weekends/holidays and other special days, and short‐term dynamics and weather regression effects, discussing the necessity of nonlinx ear functions for cooling effects. Our developments explore the facilities of dynamic linear models such as the use of discount factors, subjective intervention, variance learning and smoothing/filtering. The elicitation of the load curve is considered in the context of subjective intervention analysis, which is especially useful to take into account the adjustments for daylight savings time. The theme of combination of probabilistic forecasting is also briefly addressed. Copyright © 2013 John Wiley & Sons, Ltd.
Empirical assessment of urban traffic congestion
Authors: Chow Andy H.F. , Santacreu Alex , Tsapakis Ioannis , Tanasaranond Garavig , Cheng Tao
Published: July 2013

This paper presents an empirical assessment of urban traffic congestion in Central London, UK. Compared with freeways or motorways, urban networks are relatively less studied because of its complexity and availability of required traffic data. This paper introduces the use of automatic number plate recognition technology to analyze the characteristic of urban traffic congestion in Central London. We also present the use of linear regression to diagnose the observed congestion and attribute them to different causes. In particular, we distinguish the observed congestion into two main components: one due to recurrent factors and the other due to nonrecurrent factors. The methodologies are illustrated through a case study of Central London Area. It is found that about 15% of the observed congestion in the region is due to nonrecurrent factors such as accidents, roadwork, special events, and strikes. Given the significance of London, the study will be valuable for transport policy evaluation and appraisal in other global cities. Copyright © 2013 John Wiley & Sons, Ltd.
Specific Neurological Phenotypes in Autism Spectrum Disorders Are Associated with Sex Representation
Authors: Ben‐Itzchak Esther , Ben‐Shachar Shay , Zachor Ditza A.
Published: July 2013

Autism spectrum disorder (ASD) is a heritable disorder occurring predominantly in males. The aim of this study was to compare sex differences in the prevalence of specific neurological phenotypes commonly described in ASD. The study included 663 participants, aged 18 months to 15 years, diagnosed with ASD. Neurological and behavioral assessments were performed using standardized tests, and obtaining medical, developmental, and familial histories from the parents. Phenotypes under investigation were macro‐ and microcephaly, developmental regression, minor neurological and musculoskeletal deficits (MNMD), and seizures. Male : female ratio in the ASD group was 6.7:1. No sex differences in autism severity, cognitive ability, and adaptive functioning were noted. Mean head circumference percentile for males (50.1 ± 25.6) was significantly larger than females (43.4 ± 30.2). Micro‐ and macrocephaly were more frequent in ASD than expected (5.9%; 18.1%, respectively). Microcephaly in females (15.1%) was significantly more prevalent than in males (4.5%). The prevalence of macrocephaly in both sexes did not differ significantly. Regression was noted in 30.2% of the females with ASD, significantly higher than in males (18.9%). MNMD was documented in 73.8% of the females, significantly higher than in males (57.1%). M:F ratio decreased in a group with two or more phenotypes (3.6:1), while male predominance was more significant in the group without phenotypes (13.6:1). Neurological phenotypes associated with ASD are more prevalent in females than in males, resulting in more complex clinical and neurological manifestations in females. Therefore, involvement of different etiologies is suggested in ASD in females. Autism Res 2013, 6: 596–604. © 2013 International Society for Autism Research, Wiley Periodicals, Inc.
Brain microdialysate, CSF and plasma pharmacokinetics of ligustrazine hydrochloride in rats after intranasal and intravenous administration
Authors: Wang Qiao , Tang Zhan , Zhang Wanggang
Published: July 2013

The aim of this work was to investigate the pharmacokinetics of ligustrazine hydrochloride (LZH) in plasma, cerebrospinal fluid (CSF) and cerebral cortex after intranasal (10 mg/kg) or intravenous administration (10 mg/kg) in male Sprague–Dawley rats. Plasma, CSF and cerebral cortex microdialysates were collected at timed intervals for the measurement of LZH by a quick and sensitive HPLC‐UV method. LZH entered the brain quickly following both routes of administration. No significant difference was observed between the AUCCSF or cortex/AUCplasma ratio of LZH after intranasal administration (38.4%, 17.4%) and that after intravenous injection (45.9%, 19.9%). The drug targeting index (DTI) was 0.85 and 0.91 in the CSF and cortex, respectively. In conclusion, LZH is rapidly absorbed into the systemic circulation following intranasal administration. There is no direct pathway for LZH transport from the nasal cavity to the brain. The rapidity and magnitude of LZH penetration into the brain indicate that intranasal administration of this agent is a promising alternative to intravenous administration. Copyright © 2013 John Wiley & Sons, Ltd.
Homosexuality via canalized sexual development: A testing protocol for a new epigenetic model
Authors: Rice William R. , Friberg Urban , Gavrilets Sergey
Published: July 2013

We recently synthesized and reinterpreted published studies to advance an epigenetic model for the development of homosexuality (HS). The model is based on epigenetic marks laid down in response to the XX vs. XY karyotype in embryonic stem cells. These marks boost sensitivity to testosterone in XY fetuses and lower it in XX fetuses, thereby canalizing sexual development. Our model predicts that a subset of these canalizing epigenetic marks stochastically carry over across generations and lead to mosaicism for sexual development in opposite‐sex offspring – the homosexual phenotype being one such outcome. Here, we begin by outlining why HS has been under‐appreciated as a commonplace phenomenon in nature, and how this trend is currently being reversed in the field of neurobiology. We next briefly describe our epigenetic model of HS, develop a set of predictions, and describe how epigenetic profiles of human stem cells can provide for a strong test of the model.
Retroviruses facilitate the rapid evolution of the mammalian placenta
Authors: Chuong Edward B.
Published: July 2013

The mammalian placenta exhibits elevated expression of endogenous retroviruses (ERVs), but the evolutionary significance of this feature remains unclear. I propose that ERV‐mediated regulatory evolution was, and continues to be, an important mechanism underlying the evolution of placental development. Many recent studies have focused on the co‐option of ERV‐derived genes for specific functional adaptations in the placenta. However, the co‐option of ERV‐derived regulatory elements could potentially lead to the incorporation of entire gene regulatory networks, which, I argue, would facilitate relatively rapid developmental evolution of the placenta. I suggest a model in which an ancient retroviral infection led to the establishment of the ancestral placental developmental gene network through the co‐option of ERV‐derived regulatory elements. Consequently, placental development would require elevated tolerance to ERV activity. This in turn would expose a continuous stream of novel ERV mutations that may have catalyzed the developmental diversification of the mammalian placenta.
Optimal adaptive two‐stage designs for phase II cancer clinical trials
Authors: Englert Stefan , Kieser Meinhard
Published: July 2013

In oncology, single‐arm two‐stage designs with binary endpoint are widely applied in phase II for the development of cytotoxic cancer therapies. Simon's optimal design with prefixed sample sizes in both stages minimizes the expected sample size under the null hypothesis and is one of the most popular designs. The search algorithms that are currently used to identify phase II designs showing prespecified characteristics are computationally intensive. For this reason, most authors impose restrictions on their search procedure. However, it remains unclear to what extent this approach influences the optimality of the resulting designs. This article describes an extension to fixed sample size phase II designs by allowing the sample size of stage two to depend on the number of responses observed in the first stage. Furthermore, we present a more efficient numerical algorithm that allows for an exhaustive search of designs. Comparisons between designs presented in the literature and the proposed optimal adaptive designs show that while the improvements are generally moderate, notable reductions in the average sample size can be achieved for specific parameter constellations when applying the new method and search strategy.
Molecular phylogeny of Neotropical bioluminescent beetles (Coleoptera: Elateroidea) in southern and central Brazil
Authors: Amaral DT , Arnoldi FGC , Rosa SP , Viviani VR
Published: July 2013

Bioluminescence in beetles is found mainly in the Elateroidea superfamily (Elateridae, Lampyridae and Phengodidae). The Neotropical region accounts for the richest diversity of bioluminescent species in the world with about 500 described species, most occurring in the Amazon, Atlantic rainforest and Cerrado (savanna) ecosystems in Brazil. The origin and evolution of bioluminescence, as well as the taxonomic status of several Neotropical taxa in these families remains unclear. In order to contribute to a better understanding of the phylogeny and evolution of bioluminescent Elateroidea we sequenced and analyzed sequences of mitochondrial NADH2 and the nuclear 28S genes and of the cloned luciferase sequences of Brazilian species belonging to the following genera: (Lampyridae) Macrolampis, Photuris, Amydetes, Bicellonycha, Aspisoma, Lucidota, Cratomorphus; (Elateridae) Conoderus, Pyrophorus, Hapsodrilus, Pyrearinus, Fulgeochlizus; and (Phengodidae) Pseudophengodes, Phrixothrix, Euryopa and Brasilocerus. Our study supports a closer phylogenetic relationship between Elateridae and Phengodidae as other molecular studies, in contrast with previous morphologic and molecular studies that clustered Lampyridae/Phengodidae. Molecular data also supported division of the Phengodinae subfamily into the tribes Phengodini and Mastinocerini. The position of the genus Amydetes supports the status of the Amydetinae as a subfamily. The genus Euryopa is included in the Mastinocerini tribe within the Phengodinae/Phengodidae. Copyright © 2013 John Wiley & Sons, Ltd.
Towards kinetic modeling of genome‐scale metabolic networks without sacrificing stoichiometric, thermodynamic and physiological constraints
Authors: Chakrabarti Anirikh , Miskovic Ljubisa , Soh Keng Cher , Hatzimanikatis Vassily
Published: July 2013

Mathematical modeling is an essential tool for the comprehensive understanding of cell metabolism and its interactions with the environmental and process conditions. Recent developments in the construction and analysis of stoichiometric models made it possible to define limits on steady‐state metabolic behavior using flux balance analysis. However, detailed information on enzyme kinetics and enzyme regulation is needed to formulate kinetic models that can accurately capture the dynamic metabolic responses. The use of mechanistic enzyme kinetics is a difficult task due to uncertainty in the kinetic properties of enzymes. Therefore, the majority of recent works considered only mass action kinetics for reactions in metabolic networks. Herein, we applied the optimization and risk analysis of complex living entities (ORACLE) framework and constructed a large‐scale mechanistic kinetic model of optimally grown Escherichia coli. We investigated the complex interplay between stoichiometry, thermodynamics, and kinetics in determining the flexibility and capabilities of metabolism. Our results indicate that enzyme saturation is a necessary consideration in modeling metabolic networks and it extends the feasible ranges of metabolic fluxes and metabolite concentrations. Our results further suggest that enzymes in metabolic networks have evolved to function at different saturation states to ensure greater flexibility and robustness of cellular metabolism.
Peptides as models for the structure and function of viral capsid proteins: Insights on dengue virus capsid
Authors: Freire João Miguel , Veiga Ana Salomé , de la Torre Beatriz G. , Santos Nuno C. , Andreu David , Da Poian Andrea T. , Castanho Miguel A. R. B.
Published: July 2013

The structural organization of viral particles is among the most astonishing examples of molecular self‐assembly in nature, involving proteins, nucleic acids, and, sometimes, lipids. Proper assembly is essential to produce well structured infectious virions. A great variety of structural arrangements can be found in viral particles. Nucleocapsids, for instance, may display highly ordered geometric shapes or consist in macroscopically amorphous packs of the viral genome. Alphavirus and flavivirus are viral genera that exemplify these extreme cases, the former comprising viral particles structured with a T = 4 icosahedral symmetry, whereas flavivirus capsids have no regular geometry. Dengue virus is a member of flavivirus genus and is used in this article to illustrate how viral protein‐derived peptides can be used advantageously over full‐length proteins to unravel the foundations of viral supramolecular assemblies. Membrane‐ and viral RNA‐binding data of capsid protein‐derived dengue virus peptides are used to explain the amorphous organization of the viral capsid. Our results combine bioinformatic and spectroscopic approaches using two‐ or three‐component peptide and/or nucleic acid and/or lipid systems. © 2013 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 100: 325–336, 2013.
Peptide antagonists of the calcitonin gene‐related peptide (CGRP) receptor with improved pharmacokinetics and pharmacodynamics
Authors: Miranda Les P. , Shi Licheng , Holder Jerry R. , Wright Marie , Gegg Colin V. , Johnson Eileen , Wild Kenneth , Stenkilsson Michael , Doellgast George , Manning Barton H. , Salyers Kevin
Published: July 2013

Antagonism of the calcitonin gene‐related peptide (CGRP) receptor may be a useful approach for migraine treatment. Selective PEGylated peptide antagonists to the CGRP receptor are described, derived from CGRP(8–37) with polymer derivatization at an engineered lysine‐25 residue. Potent PEGylated peptides with improved pharmacokinetics were identified through peptide side‐chain modification to mitigate metabolic liabilities. PEGylated Ac‐Trp‐[Cit11,18,hArg24,Lys25,Asp31,Pro34,1‐Nal35]CGRP(8–37)‐NH2, 9, elicits a dose‐dependent reduction of intradermal CGRP‐induced local blood flow in rodents with an ED50 of 0.52 mg kg−1 without any overt adverse effects. © 2013 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 100: 422–430, 2013.
Advances in turbulent mixing techniques to study microsecond protein folding reactions
Authors: Kathuria Sagar V. , Chan Alexander , Graceffa Rita , Paul Nobrega R. , Robert Matthews C. , Irving Thomas C. , Perot Blair , Bilsel Osman
Published: July 2013

Recent experimental and computational advances in the protein folding arena have shown that the readout of the one‐dimensional sequence information into three‐dimensional structure begins within the first few microseconds of folding. The initiation of refolding reactions has been achieved by several means, including temperature jumps, flash photolysis, pressure jumps, and rapid mixing methods. One of the most commonly used means of initiating refolding of chemically denatured proteins is by turbulent flow mixing with refolding dilution buffer, where greater than 99% mixing efficiency has been achieved within 10's of microseconds. Successful interfacing of turbulent flow mixers with complementary detection methods, including time‐resolved Fluorescence Spectroscopy (trFL), Förster Resonance Energy Transfer, Circular Dichroism, Small‐Angle X‐ray Scattering, Hydrogen Exchange followed by Mass Spectrometry and Nuclear Magnetic Resonance Spectroscopy, Infrared Spectroscopy (IR), and Fourier Transform IR Spectroscopy, has made this technique very attractive for monitoring various aspects of structure formation during folding. Although continuous‐flow (CF) mixing devices interfaced with trFL detection have a dead time of only 30 µs, burst phases have been detected in this time scale during folding of peptides and of large proteins (e.g., CheY and TIM barrels). Furthermore, a major limitation of the CF mixing technique has been the requirement of large quantities of sample. In this brief communication, we will discuss the recent flurry of activity in micromachining and microfluidics, guided by computational simulations, which are likely to lead to dramatic improvements in time resolution and sample consumption for CF mixers over the next few years. © 2013 Wiley Periodicals, Inc. Biopolymers 99: 888–896, 2013.
Characterization of hyaluronic acid and synovial fluid in stagnation point elongational flow
Authors: Haward Simon J.
Published: July 2013

Hyaluronic acid (HA) is an important biomacromolecule, which fulfils a number of vital physiological functions (especially in the joint synovial fluid) and also has consumer and pharmaceutical applications. HA solution properties have already been quite thoroughly characterized in response to steady shear flows but are less well understood in highly deforming extensional flows. In this study, flow‐induced birefringence measurements are made as a function of the strain rate in planar elongational flow at the stagnation point of a cross‐slot device using HA solutions of a range of molecular weightsand at dilute concentrations. The results provide macromolecular relaxation times, molecular weight distributions and the extensional viscosities and Trouton ratios of the fluids. The HA relaxation time is found to vary as1.8, which is consistent with a partially solvated, expanded coil. An intrinsic Trouton ratio is defined, which varies as2. The measurement of birefringence with strain rate is shown to be highly sensitive to the molecular weight distribution and can resolve subtle changes due to macromolecular degradation and the presence of fracture products. Mechanical degradation experiments in the cross‐slots indicate midchain scission of HA macromolecules, strongly suggesting near full extension of the high‐molecular weight fraction in the stagnation point extensional flow field. Taken together the results suggest a possible method for analysis of the HA in synovial fluid, and this concept is tested using synovial fluid obtained from porcine tarsal joint. © 2013 Wiley Periodicals, Inc. Biopolymers 101: 287–305, 2014.
LC‐ESI‐MS/MS analysis and pharmacokinetics of jolkinolide B, a potential antitumor active component isolated from Euphorbia fischeriana, in rat plasma
Authors: Li Yang , Liu Xiao‐Li , Cai Zhen‐Gang , Zhang Si‐Xi
Published: July 2013

A simple, specific and reproducible liquid chromatography–electrospray ionization mass spectrometry was developed and validated for the determination of jolkinolide B, a potential antitumor active component isolated from Euphorbia fischeriana, in rat plasma. Chromatographic separation was achieved on a Venusil MP‐C18 column using an isocratic elution. Jolkinolide B and osthole (internal standard) were monitored by positive electrospray ionization in the selected reaction monitoring mode. Good linearity (r2 > 0.996) was achieved by a weighted (1/x2) linear least‐squares regression over a concentration range of 6.50–2600 ng/mL. The accuracy and precision of the assay were satisfactory and the method proved to be applicable to pharmacokinetics following a single intravenous bolus injection of jolkinolide B to rats. Copyright © 2013 John Wiley & Sons, Ltd.
Phytal: A Candidate Sex Pheromone Component of the Moroccan Locust Dociostaurus maroccanus
Authors: Fürstenau Benjamin , Muñoz Lourdes , Coca‐Abia Milagro , Rosell Gloria , Guerrero Angel , Quero Carmen
Published: July 2013

Outbreaks of locusts cause enormous economic losses to agriculture in many countries. To develop environmentally friendly strategies for their control, much research has been focused on the factors that influence locust biology, particularly infochemical‐mediated interactions. We present herein the identification and synthesis of both Z and E isomers of phytal (3,7,11,15‐tetramethylhexadec‐2‐enal, 1), which are involved in chemical communication and behaviour of the Moroccan locust, Dociostaurus maroccanus, a serious agricultural pest. The compound was identified by comparison of its chromatographic and spectrometric features and microchemical reactions with those of a synthetic sample. The natural compound was shown to have the R,R configuration by chiral HPLC analysis, and its structure is unique as an insect pheromone component. Both isomers of phytal are produced by sexually mature adult males and elicit electroantennographic responses in antennae of both sexes. In two‐choice olfactometer bioassays, males and females significantly preferred the stream enriched with racemic phytal to the control. In contrast, hydrogenated phytal was behaviourally inert. Both isomers of phytal are specific to D. maroccanus as they are absent in the closely related, habitat‐sharing species Dociostaurus jagoi and Calliptamus wattenwylianus. Legs and wings are the main release sites of the compound: approximately 90 % of that emitted by living individuals. In biosynthetic studies, phytal appears to proceed from oxidation of phytol (2) after injection of deuterated phytol into the abdomen of the insect or after administration in the diet. Our results demonstrate that phytal is a candidate sex pheromone component of the Moroccan locust; it is produced by mature males, and might be eavesdropped upon by conspecific males.
Strand Invasion of DNA Quadruplexes by PNA: Comparison of Homologous and Complementary Hybridization
Authors: Gupta Anisha , Lee Ling‐Ling , Roy Subhadeep , Tanious Farial A. , Wilson W. David , Ly Danith H. , Armitage Bruce A.
Published: July 2013

Molecular recognition of DNA quadruplex structures is envisioned to be a strategy for regulating gene expression at the transcriptional level and for in situ analysis of telomere structure and function. The recognition of DNA quadruplexes by peptide nucleic acid (PNA) oligomers is presented here, with a focus on comparing complementary, heteroduplex‐forming and homologous, heteroquadruplex‐forming PNAs. Surface plasmon resonance and optical spectroscopy experiments demonstrated that the efficacy of a recognition mode depended strongly on the target. Homologous PNA readily invades a quadruplex derived from the promoter regulatory region found upstream of the MYC proto‐oncogene to form a heteroquadruplex at high potassium concentration mimicking the intracellular environment, whereas complementary PNA exhibits virtually no hybridization. In contrast, complementary PNA is superior to the homologous in hybridizing to a quadruplex modeled on the human telomere sequence. The results are discussed in terms of the different structural morphologies of the quadruplex targets and the implications for in vivo recognition of quadruplexes by PNAs.
Complete percutaneous approach for arterial access in transfemoral transcatheter aortic valve replacement: A comparison with surgical cut‐down and closure
Authors: Nakamura Mamoo , Chakravarty Tarun , Jilaihawi Hasan , Doctor Niraj , Dohad Suhail , Fontana Gregory , Cheng Wen , Makkar Raj R.
Published: July 2013

Objectives

This study sought to investigate the immediate safety and feasibility of complete percutaneous access/closure of arteriotomy for device deployment compared to the surgical approach for transfemoral transcatheter aortic valve replacement (TAVR).

Background

The percutaneous approach for arterial access for device deployment in transfemoral TAVR is a potential alternative to the surgical approach.

Methods

In 274 patients who underwent transfemoral TAVR using Edward Sapien heart valve, 140 had a complete percutaneous approach using a “pre‐closure” technique whereas 134 had surgical cut‐down/repair for arterial access/closure of device deployment. Immediate vascular access/closure success, associated complications and clinical outcomes were compared.

Results

While overall acute success of access/closure and in‐hospital access‐related events were similar, significant isolated stenosis/dissection at the access site developed more frequently in the percutaneous group (7.1% vs. 0.7%, P = 0.007). Contrary, wound infections requiring prolonged antibiotics use or surgical debridement occurred more frequently in the surgical group (0.7% vs. 6.7%, P = 0.007). Although the rate of major vascular complications was not different, the surgical group developed more frequent minor bleeding (27.1% vs. 38.8%, P = 0.04) and underwent transfusion of packed red blood cells of ≤3 units (25.7% vs. 43.3%, P = 0.002). Median hospital stay was shorter in the percutaneous group (3 days vs. 4 days, P = 0.002).

Conclusions

The percutaneous approach is a feasible access/closure method with a potential of lowering access site infection and bleeding, and shortening hospital stay, while maintaining similar rates of major vascular complications compared to the surgical approach. © 2013 Wiley Periodicals, Inc.
The long‐term outcomes of transcoronary ablation of septal hypertrophy compared to surgical myectomy in patients with symptomatic hypertrophic obstructive cardiomyopathy
Authors: Samardhi Himabindu , Walters Darren L , Raffel Christopher , Rateesh Shruti , Harley Catherine , Burstow Darryl , Pohlner Peter , Aroney Con
Published: July 2013

Objectives

The aim of this study was to compare the long‐term outcomes of transcoronary ablation of septal hypertrophy (TASH) with open surgical myomectomy (SM) in patients with symptomatic hypertrophic obstructive cardiomyopathy (HOCM).

Methods

We reviewed patients who underwent either procedure at our institution. The demographics, clinical outcomes, echocardiographic parameters, and complications were compared.

Results

Seventy patients with HOCM were treated with either TASH (n = 47, 26 male) or SM (n = 23, 10 male). Compared to those treated with SM, patients undergoing TASH were older (57+/− 14.7 years versus 47 +/− 20.6 years, P = 0.021) and more symptomatic. A higher proportion of patients had syncope as a presenting feature in the TASH group compared to the SM group (57.5% vs. 17.4%, P = 0.002) respectively. They were also more likely to be in New York Heart Association (NYHA) class III/IV compared to the patients who underwent SM (85.1% vs. 39.1%; P < 0.001). Patients were followed for a mean period of 43 months (TASH) and 46 months (SM). Repeat procedures were more common in the TASH group (17% vs. 0%, P = 0.04) but mitral valve replacement was more common in the SM group (0% vs. 8.7%, P = 0.105). Symptom improvement, the rate of complications and all cause mortality rates were similar in both groups.

Conclusions

TASH compares favorably with surgical myectomy with regard to symptom resolution, rate of complications and mortality in a tertiary referral centre and should be seen as an attractive alternative to surgical myectomy in the appropriate patient population. © 2013 Wiley Periodicals, Inc.
Two‐week interval optical coherence tomography: Imaging evidence on neointimal coverage completion after implantation of the endeavor zotarolimus‐eluting stent
Authors: Nishinari Makoto , Shimohama Takao , Tojo Taiki , Shiono Takaaki , Shinagawa Hisahito , Kameda Ryo , Aoyama Naoyoshi , Izumi Tohru
Published: July 2013

Objective

To obtain imaging evidence by 2‐week optical coherence tomography (OCT) on the completion of neointimal coverage (NIC; the percentage of stent strut coverage and thickness of the formed neointima) completion after implantation of the Endeavor zotarolimus‐eluting stent (E‐ZES).

Background

Despite the fact that NIC is a cardinal process in the pathomechanism of late stent thrombosis, little imaging information is available on morphological changes thereof on a short‐time interval basis.

Methods

27 Japanese patients with stable angina pectoris and de novo native coronary artery lesions were enrolled, and 27 lesions (30 implantations) were examined. OCT was performed at weeks 2, 4, 6, 8, and 10 after E‐ZES implantation. NIC was examined using cross‐sectional OCT images obtained at the 1.0‐mm intervals.

Results

In total, 621 cross‐sectional OCT images, which depicted 7,747 stent struts, were analyzed. The mean percentages of stent strut coverage at weeks 2, 4, 6, 8, and 10 after E‐ZES implantation were 12.3, 70.4, 67.9, 86.0, and 99.2%, respectively; a marked increase was found between weeks 2 and 4. The mean thicknesses of the formed neointima were 40.2, 52.1, 48.1, 86.5, and 146.2 μm at respective weeks, with the high‐signal and thick neointima (146 µm) at week 10. An intracoronary thrombus was detected in only one stent at week 4.

Conclusions

The full circumferential coverage of the vessel wall by the high‐signal neointima was found at as early as week 10 after E‐ZES implantation, imparting a surrogate index for vascular healing by NIC. © 2013 Wiley Periodicals, Inc.
Formation of Propane in the Aqueous‐Phase Processing of 1‐Propanol over Platinum: A DFT Study
Authors: Chiu Cheng‐chau , Genest Alexander , Rösch Notker
Published: July 2013

The reaction pathways for alkane formation from alcohols in aqueous‐phase (AP) processing was studied computationally for the model system 1‐propanol over flat and stepped surfaces of Pt. We examined the dehydration–hydrogenation (DH) mechanism in an acidic environment and alcohol hydrogenolysis (AH) under neutral conditions. The highest (relative) barrier of the DH mechanism was calculated at approximately 90 kJ mol−1on Pt(1 1 1), which occurs in the hydrogenation step after cleavage of the CO bond. The highest relative barrier of the AH mechanism, if the CO bond is cleaved on Pt(1 1 1), is slightly higher, 105 kJ mol−1. The corresponding elementary reaction step does not start from the alcohol, but a dehydrogenated intermediate. On Pt(2 2 1), transition state geometries differ somewhat and the highest relative barriers of both mechanisms, AH and DH, are lower by 8–40 kJ mol−1, than the corresponding barriers on Pt(1 1 1).
Solvent Effect and Reactivity Trend in the Aerobic Oxidation of 1,3‐Propanediols over Gold Supported on Titania: NMR Diffusion and Relaxation Studies
Authors: D'Agostino Carmine , Kotionova Tatyana , Mitchell Jonathan , Miedziak Peter J. , Knight David W. , Taylor Stuart H. , Hutchings Graham J. , Gladden Lynn F. , Mantle Mick D.
Published: July 2013

In recent work, it was reported that changes in solvent composition, precisely the addition of water, significantly inhibits the catalytic activity of Au/TiO2 catalyst in the aerobic oxidation of 1,4‐butanediol in methanol due to changes in diffusion and adsorption properties of the reactant. In order to understand whether the inhibition mechanism of water on diol oxidation in methanol is generally valid, the solvent effect on the aerobic catalytic oxidation of 1,3‐propanediol and its two methyl‐substituted homologues, 2‐methyl‐1,3‐propanediol and 2,2‐dimethyl‐1,3‐propanediol, over a Au/TiO2 catalyst has been studied here using conventional catalytic reaction monitoring in combination with pulsed‐field gradient nuclear magnetic resonance (PFG‐NMR) diffusion and NMR relaxation time measurements. Diol conversion is significantly lower when water is present in the initial diol/methanol mixture. A reactivity trend within the group of diols was also observed. Combined NMR diffusion and relaxation time measurements suggest that molecular diffusion and, in particular, the relative strength of diol adsorption, are important factors in determining the conversion. These results highlight NMR diffusion and relaxation techniques as novel, non‐invasive characterisation tools for catalytic materials, which complement conventional reaction data.
Reactivity of Dialumane and “Dialumene” Compounds toward Alkenes
Authors: Zhao Yanxia , Lei Yibo , Dong Qingsong , Wu Biao , Yang Xiao‐Juan
Published: July 2013

The reactions of dialumane [L(thf)AlAl(thf)L] (1, L=[{(2,6‐iPr2C6H3)NC(Me)}2]2−) with stilbene and styrene afforded the oxidation/insertion products [L(thf)Al(CH(Ph)CH(Ph))AlL] (2) and [L(thf)Al(CH(Ph)CH2)Al(thf)L] (3), respectively. In the presence of Na metal, precursor 1 reacted with butadienes, possibly through the reduced “dialumene” or the “carbene‐like” :AlL species, to yield aluminacyclopentenes [LAl(CH2C(Me)C(Me)CH2)Na]n (4 a) and [Na(dme)3][LAl(CH2C(Me)CHCH2)] (4 b, dme=dimethoxyethane) as [1+4] cycloaddition products, as well as the [2+4] cycloaddition product 1,6‐dialumina‐3,8‐cyclodecadiene, [{Na(dme)}2][LAl(CH2C(Me)C(Me)CH2)2AlL] (5). The possible mechanisms of the cycloaddition reactions were studied by using DFT computations.
Aryl‐Phosphonate Lanthanide Complexes and Their Fluorinated Derivatives: Investigation of Their Unusual Relaxometric Behavior and Potential Application as Dual Frequency 1H/19F MRI Probes
Authors: Placidi Matteo P. , Botta Mauro , Kálmán Ferenc K. , Hagberg Gisela E. , Baranyai Zsolt , Krenzer Andreas , Rogerson Alexandria K. , Tóth Imre , Logothetis Nikos K. , Angelovski Goran
Published: July 2013

A series of low molecular weight lanthanide complexes were developed that have high 1H longitudinal relaxivities (r1) and the potential to be used as dual frequency 1H and 19F MR probes. Their behavior was investigated in more detail through relaxometry, pH‐potentiometry, luminescence, and multinuclear NMR spectroscopy. Fitting of the 1H NMRD and 17O NMR profiles demonstrated a very short water residence lifetime (<10 ns) and an appreciable second sphere effect. At lower field strengths (20 MHz), two of the complexes displayed a peak in r1 (21.7 and 16.3 mM−1 s−1) caused by an agglomeration, that can be disrupted through the addition of phosphate anions. NMR spectroscopy revealed that at least two species are present in solution interconverting through an intramolecular binding process. Two complexes provided a suitable signal in 19F NMR spectroscopy and through the selection of optimized imaging parameters, phantom images were obtained in a MRI scanner at concentrations as low as 1 mM. The developed probes could be visualized through both 1H and 19F MRI, showing their capability to function as dual frequency MRI contrast agents.
Spontaneous Translocation of Antitumor Oxaliplatin, its Enantiomeric Analogue, and Cisplatin from One Strand to Another in Double‐Helical DNA
Authors: Malina Jaroslav , Natile Giovanni , Brabec Viktor
Published: July 2013

Oxaliplatin and cisplatin belong to the class of platinum‐based anticancer agents. Formation of DNA adducts by these complexes and the consequences for its structure and function, is the mechanistic paradigm by which these drugs exert their antitumor activity. We show that employing short oligonucleotide duplexes containing single, site‐specific 1,3‐intrastrand cross‐links of oxaliplatin, its enantiomeric analogue, or cisplatin and by using gel electrophoresis that under physiological conditions the coordination bonds between platinum and the N7 position of guanine residues involved in the cross‐links of the PtII complexes can be cleaved. This cleavage may lead to linkage isomerization reactions between these metallodrugs and double‐helical DNA. For instance, approximately 25 % 1,3‐intrastrand cross‐links of the platinum complexes isomerized after 192 h (at 310 K in 200 mM NaClO4). Differential scanning calorimetry of duplexes containing single, site‐specific cross‐links of oxaliplatin, its enantiomeric analogue, and cisplatin reveals that one of the driving forces that leads to the lability of DNA cross‐links of these metallodrugs is a difference between the thermodynamic destabilization induced by the cross‐link and by the adduct into which it could isomerize. The rearrangements may proceed in the way that cross‐links originally formed in one strand of the DNA can spontaneously translocate from one DNA strand to its complementary counterpart, which may evoke walking of the platinum complex on DNA molecule. In addition, the differences in the kinetics of the rearrangement reactions and the thermodynamic destabilization of DNA observed for adducts of oxaliplatin and its enantiomeric analogue confirm that the chirality at the carrier 1,2‐diaminocyclohexane ligand can considerably affect structural and other physical properties of DNA adducts and consequently their biological effects. In aggregate, interesting generalization of the results described in this work might be that the migration of oxaliplatin, its enantiomeric analogue, or cisplatin from one strand to another in double‐helical DNA controlled by energetic signatures of these agents might contribute to a better understanding of their cytotoxic and mutagenic potential.
Staphylococcus aureus Penicillin‐Binding Protein 2 Can Use Depsi‐Lipid II Derived from Vancomycin‐Resistant Strains for Cell Wall Synthesis
Authors: Nakamura Jun , Yamashiro Hidenori , Miya Hiroto , Nishiguchi Kenzo , Maki Hideki , Arimoto Hirokazu
Published: July 2013

Vancomycin‐resistant Staphylococcus aureus (S. aureus) (VRSA) uses depsipeptide‐containing modified cell‐wall precursors for the biosynthesis of peptidoglycan. Transglycosylase is responsible for the polymerization of the peptidoglycan, and the penicillin‐binding protein 2 (PBP2) plays a major role in the polymerization among several transglycosylases of wild‐type S. aureus. However, it is unclear whether VRSA processes the depsipeptide‐containing peptidoglycan precursor by using PBP2. Here, we describe the total synthesis of depsi‐lipid I, a cell‐wall precursor of VRSA. By using this chemistry, we prepared a depsi‐lipid II analogue as substrate for a cell‐free transglycosylation system. The reconstituted system revealed that the PBP2 of S. aureus is able to process a depsi‐lipid II intermediate as efficiently as its normal substrate. Moreover, the system was successfully used to demonstrate the difference in the mode of action of the two antibiotics moenomycin and vancomycin.
Cascade‐ and Orthoamide‐Type Overman Rearrangements of Allylic Vicinal Diols
Authors: Nakayama Yasuaki , Sekiya Ruriko , Oishi Hiroki , Hama Naoto , Yamazaki Miki , Sato Takaaki , Chida Noritaka
Published: July 2013

This article describes the details of two new types of Overman rearrangement from allylic vicinal diols. Starting from identical diols, both bis(imidate)s and cyclic orthoamides were selectively synthesized by simply changing the reaction conditions. Whilst exposure of the bis(imidate)s to thermal conditions initiated the double Overman rearrangement to introduce two identical nitrogen groups in a single operation (the cascade‐type Overman rearrangement), the reaction of cyclic orthoamides resulted in a single rearrangement (the orthoamide‐type Overman rearrangement). The newly generated allylic alcohols from the orthoamide‐type reaction can potentially undergo a variety of further transformations. For instance, we demonstrated an Overman/Claisen sequence in one pot. The most conspicuous feature of this method is that it offers precise control over the number of Overman rearrangements from the same allylic vicinal diols. This method also excludes the tedious protecting‐group manipulations of the homoallylic alcohols, which are necessary in conventional Overman rearrangements. All of the performed rearrangements proceeded in a completely diastereoselective fashion through a chair‐like transition state.
Size‐Dependent Enhancement of Electrocatalytic Oxygen‐Reduction and Hydrogen‐Evolution Performance of MoS2 Particles
Authors: Wang Tanyuan , Gao Dongliang , Zhuo Junqiao , Zhu Zhiwei , Papakonstantinou Pagona , Li Yan , Li Meixian
Published: July 2013

MoS2 particles with different size distributions were prepared by simple ultrasonication of bulk MoS2 followed by gradient centrifugation. Relative to the inert microscale MoS2, nanoscale MoS2 showed significantly improved catalytic activity toward the oxygen‐reduction reaction (ORR) and hydrogen‐evolution reaction (HER). The decrease in particle size was accompanied by an increase in catalytic activity. Particles with a size of around 2 nm exhibited the best dual ORR and HER performance with a four‐electron ORR process and an HER onset potential of −0.16 V versus the standard hydrogen electrode (SHE). This is the first investigation on the size‐dependent effect of the ORR activity of MoS2, and a four‐electron transfer route was found. The exposed abundant Mo edges of the MoS2 nanoparticles were proven to be responsible for the high ORR catalytic activity, whereas the origin of the improved HER activity of the nanoparticles was attributed to the plentiful exposed S edges. This newly discovered process provides a simple protocol to produce inexpensive highly active MoS2 catalysts that could easily be scaled up. Hence, it opens up possibilities for wide applications of MoS2 nanoparticles in the fields of energy conversion and storage.
Re‐examination of the C6Li6 Structure: To Be, or not To Be Symmetric
Authors: Moreno Diego , Martínez‐Guajardo Gerardo , Díaz‐Celaya Andrés , Mercero José M. , de Coss Romeo , Perez‐Peralta Nancy , Merino Gabriel
Published: July 2013

The potential energy surface of C6Li6 was re‐examined and a new non‐symmetric global minimum was found. The new structure can be described as three C22− fragments strongly aggregated through lithium bridges. At high temperatures, fluxionality is perceived instead of dissociation. At 600 and 900 K, the BOMD simulations show that the lithium mobility is high, indicating that the cluster behaves in a liquid‐like manner (BOMD=Born–Oppenheimer molecular dynamics).
Propagation of Biochirality: Crossovers and Nonclassical Crystallization Kinetics of Aspartic Acid in Water
Authors: Lee Tu , Lin Yu Kun , Tsai Ya Chung , Lee Hung Lin
Published: July 2013

All experimental procedures discussed could be treated as a screening tool for probing the existence of molecular association among the chiral molecules and the solvent system. The molecular association phases of a racemic conglomerate solution (CS) and a racemic compound solution (RCS), and the templating effect of aspartic acid solid surface were observed to minimize the chance of redissolving racemic conglomerate and racemic compound aspartic acid in water and reforming an RCS in crossovers experiments. Only 1 %wt% of l‐aspartic acid was adequate enough to induce a transformation from a racemic compound aspartic acid to a racemic conglomerate aspartic acid. This would make the propagation of biochirality more feasible and sound. However, tetrapeptide, (l‐aspartic acid)4, failed to induce enantioseparation as templates purely by crystallization. Nonclassical crystallization theory was needed to take into account the existence of a CS. Fundamental parameters of the crystallization kinetics such as the induction time, interfacial energy, Gibbs energetic barrier, nucleation rate, and critical size of stable nuclei of: (i) racemic compound aspartic acid, (ii) racemic compound aspartic acid seeded with 1 %wt% l‐aspartic acid, (iii) racemic conglomerate aspartic acid, and (iv) l‐aspartic acid were evaluated and compared with different initial supersaturation ratios. Morphological studies of crystals grown from the crystallization kinetics were also carried out.Chirality 25:768–779, 2013. © 2013 Wiley Periodicals, Inc.
Elutriation in inverse fluidisation using non‐Newtonian pseudoplastic liquids
Authors: Das Bimal , Ganguly Uma Prasad , Das Sudip Kumar
Published: July 2013

Experiments have been carried out to determine the minimum elutriation velocity for inverse fluidisation system using single and binary systems of four different solids of polymeric materials of different sizes and shapes, and four different non‐Newtonian pseudoplastic liquids in two different Perspex columns. The effects of different operating parameters on elutriation velocity have been investigated. Empirical correlations have been developed to predict the minimum elutriation velocity as a function of physical and dynamic variables of the system. Statistical analysis of the correlation suggests that is of acceptable accuracy.
Phase Evolution of CuS System in Ethylene Glycol Solution: the Effect of Anion and PVP on the Transformation of Thiourea
Authors: Fang Zhen , Wang Chenyan , Fan Fan , Hao Shenghua , Long Liuyang , Song Yixuan , Qiang Tingting
Published: July 2013

The transformation mechanisms of thiourea in ethylene glycol solution was systematically investigated in this report, which shows the transformation process is influenced by the anion (NO3−, Cl−, Br−) and polyvinylpyrrolidone (PVP). Thiourea (tu) isomerizes into ammonium thiocyanate when NO3− is present, regardless of the existence of PVP. For Cl−, thiourea coordinates with copper anion to form [Cu(tu)]Cl·1/2H2O complex whether PVP is present. When it comes to Br−, thiourea hydrolyzes in the cooperation of PVP or coordinates with copper anion to form [Cu(tu)Br]·1/2H2O complex without PVP. The different transformation routes will lead to different phase evolution of the CuS system. This work may provide a new understanding of the transformation of thiourea in ethylene glycol solution. The optical properties of the as‐prepared copper sulfides exhibit signi?cant stoichiometry‐dependent features which may have potential applications in semiconductor photovoltaic devices.