bluuebunny/crossref_metadata_2025 huggingface dataset:
Dual Mass Flywheel
Authors: Kroll Jürgen , Kooy Ad
Published: April 2015

The most effective measure for optimum vibration isolation of petrol and diesel engines with a high specific power rating and a high specific torque is the use of a dual mass flywheel (DMF). In this component, a spring mass damper is activated before the clutch. Its resonance frequency is below the excitation frequency of the engine at idle speed and thus outside the operating range. The spring mass damper filters the torsional vibrations introduced by the engine and thus calms the downstream drive line.

This contribution provides an introductory analysis of the relationship between the trend for downsizing on the one hand and greater torsional vibrations and their noise development on the other. The function and structure of theDMFbasic concept and the further models derived from this basic concept are described later. The speed‐adaptive absorbing function of theDMFwith centrifugal pendulum‐type absorber (CPA) is presented in detail. A separate chapter describes a procedure for vibration simulation that looks in detail at all elements and excitation objects that come under consideration for the power transfer. This chapter looks not only at theDMFand the clutch system but also the entire powertrain, including engine and engine management. It also discusses the selection of suitable target factors that can be used to assess the quality of the design.
Open Differentials
Authors: Palazzolo Joseph
Published: April 2015

Open differentials have been installed in automotive applications for over 100 years. This chapter reviews the primary need and basic function of a differential for automotive applications. The mechanical power flow and construction of an open differential are presented along with the shortcomings of such a device. From the basic construction, one of many analytical approaches that is applied to explain the behavior of the differential and torque bias ratios from the internal friction within the device is reviewed. The elements of the differential are reviewed; specifically, the differential carrier, pin, pinion gears, and side gears. The general configuration and differences between two‐ and four‐pinion differentials are presented and explained.
Control Systems and Strategies for Automated Manual and Double Clutch Transmissions
Authors: Müller Bruno , Rathke Götz , Reuschel Michael , Wagner Uwe , Winkelmann Stefan , Grethel Marco , Gerhart Jürgen
Published: April 2015

Automated manual transmissions (AMT) and double clutch transmissions (DCT) can increase comfort while simultaneously reducing fuel consumption and emissions. To implementAMTandDCTinto a vehicle powertrain, numerous hardware components have to work together. These include several design variants of electric motors, control units, sensors, and, depending on the design, an electrohydraulic, electromechanical, or hydrostatic actuating mechanism. Depending on the combination and design of these components, various concepts can be considered and transmission types developed that satisfy not only the specific requirements of theOEMsbut also the individual applications. From a software perspective, the higher level functional logic is particularly important. Through appropriate control logic and adaption routines, this functional logic must ensure a consistently high level of comfort over the entire life.

Irrespective of the specific design, an automatic transmission is only part of the overall vehicle system. The high complexity and the strong interaction between the subsystems require intensive alignment and testing of the subsystems as well as the overall system. If the automated forms of manual transmission are also to expand in other markets and compete with classic automatic transmissions, however, further improvements must be implemented in terms of efficiency (including weight and mounting space), comfort, and cost.
Emission Control Systems—Oxides of Nitrogen
Authors: Song Soonho
Published: April 2015

Facing the strict emission regulations for oxides of nitrogen (NOX), many approaches have been proposed and applied to controlNOXemissions from current engine systems. Representative de‐NOXtechnologies inSIandCIengines are introduced in terms of in‐cylinder control and aftertreatment system. In‐cylinder control such as the spark timing, fuel injection strategies, exhaust gas recirculation (EGR), and induction system (boosted engine with charge air cooling) provides means ofNOXreduction before and during the combustion process by decreasing the gas temperature and controlling the chemical reactions of combustion. On the contrary, the aftertreatment systems such as the three‐way catalytic converter (TWC), selective catalytic reduction (SCR), andNOXadsorber provide the means to reduce already formedNOXafter combustion process via chemical reactions between the exhaust gas and other chemical components such as the reductant, oxidizer, and catalysts. In this section, the basic principles of operation are discussed. Then, applications of integrated de‐NOXtechnologies are introduced in the commercial engine systems.
Multidimensional Simulation
Authors: Reitz Rolf D. , Rutland Christopher J.
Published: April 2015

The combustion process inICengines is characterized by complex multiphase, turbulent reacting flows that span multiple regimes, including premixed flame propagation, mixing‐controlled burning, and chemical kinetics‐controlled processes. For predictive modeling, these processes must be represented with accurate mathematical models and numerical schemes, and this chapter reviews the current state of the art. Zero‐dimensional models based on thermodynamic cycle analysis can require extensive model constant tuning. Multidimensional computational fluid dynamics (CFD) modeling reduces the amount of model calibration required. However, submodels must still be used to describe processes that occur on time and length scales too small to be resolved in a simulation, but the inclusion of more and more detail has been made possible by recent dramatic increases in computer power. It is now widely recognized that engineCFDsimulations can offer significant advantages in the engine development process, including being able to provide detailed in‐cylinder information, which is often inaccessible in experiments. Other advantages over engine experiments include lower cost, the ability to explore wider ranges of parameter variation, and the ability to separate and monitor individual processes. In addition, when coupled with optimization tools, new design concepts can be discovered using multidimensional modeling, as described with examples in this chapter.
Lubrication and Friction
Authors: Wong Victor W.
Published: April 2015

This chapter describes in brief the basic lubrication and friction processes at the major engine components. It starts with a clarification of the common descriptors of mechanical losses and friction in the engine, followed by the topic of lubrication fundamentals such as lubrication regimes. Then the lubrication of the contacting surfaces in each of the major engine subsystems is discussed in turn. These subsystems include the piston assembly: ring‐pack/liner, piston‐skirt/liner, piston‐pin/connecting‐rod contacts; connecting rod and crankshaft bearings; and the valvetrain subsystem. The relative contributions to total friction from the various subsystems are discussed, with the piston‐assembly contributing to about half of the total friction. The remainder of the friction comes from the crankshaft, connecting rod, and camshaft bearings, and the valvetrain oscillating parts. The bearings are in predominantly hydrodynamic lubrication, in contrast to the valvetrain oscillating components, which are characterized to be mostly in the mixed/boundary lubrication regimes. Lubricating oil composition is discussed in the final section. It is generally believed that the bulk oil viscosity, with proper viscosity and (boundary) friction modification, could be controlled to lower component friction, in conjunction with antiwear additives. Effects of lubricant‐derived ash on diesel particulate filter (DPF) restriction are significant, with large differences observed among lubricant‐derived ash originating from different metallic‐based additives—such as among calcium, magnesium, or zinc compounds—at the same mass accumulation.
EV Auxiliaries
Authors: Jin Gang , Liao Yuefeng
Published: April 2015

This chapter presents an overview of the auxiliary subsystems of an electric vehicle. The phrase
engine auxiliaries
in a conventional vehicle equipped with an internal combustion engine often refers to the components driven by the engine
auxiliary belt
, for example, the alternator, the
AC
compressor, the hydraulic power‐assisted steering pump, and sometimes to the components driven by the engine vacuum circuits, for example, the brake booster. Owing to the absence of the internal combustion engine in an electric vehicle, the aforementioned components and the corresponding subsystems at large must be redesigned with different power source and possibly different operation mechanisms. The core of the design challenge is to maximize energy usage efficiency to ensure adequate driving range of the electric vehicle. Many of the technologies employed by this redesign for electric vehicles have been under development for conventional vehicles to improve fuel efficiencies and other performance measures. This trend is popularly referred to as
electrification
where energy is increasingly stored and delivered in the form of electricity. The progress toward electric vehicles only helps intensify this development by demanding maximum energy usage efficiency and by offering a naturally available high voltage power net that can further enhance efficiency over the 12V system.
Various Types of Sensors
Authors: Igarashi Shinya , Onozuka Junji , Hoshika Hiroaki , Hayashi Masahide
Published: April 2015

This chapter describes various sensors. Firstly, general discussions of sensors for automotive application are performed. Then, airflow sensor, rotation sensor, knock sensor, temperature sensor, humidity sensor, and combined inertia sensors (acceleration and angular rate sensors) are explained.
Impact of Electric Vehicles on Low Voltage Supply Systems
Authors: Rehtanz Christian , Rolink Johannes , Horenkamp Willi
Published: April 2015

Electric vehicles represent extra loads that were not considered when the power grid was designed. As more and moreEVsare added, the grid may begin to experience local bottlenecks. This chapter thus looks at the impact of widespreadEVdeployment on the low voltage supply system in Germany. The analysis focuses on reference supply systems that are identified using structural data. It first determines the simultaneity behavior of electric vehicles based on uncontrolled charging processes. Next, it explains the methodology used to determine the reference supply systems. Then, it describes the main bottlenecks to connectEVsto the power grid. Finally, it analyzes the capacity of the low voltage supply system.
Donor‐Induced Performance Tuning of Amorphous SrTiO3 Memristive Nanodevices: Multistate Resistive Switching and Mechanical Tunability
Authors: Nili Hussein , Walia Sumeet , Kandjani Ahmad Esmaielzadeh , Ramanathan Rajesh , Gutruf Philipp , Ahmed Taimur , Balendhran Sivacarendran , Bansal Vipul , Strukov Dmitri B. , Kavehei Omid , Bhaskaran Madhu , Sriram Sharath
Published: April 2015

Metal–oxide valence‐change memristive devices are the key contenders for the development of multilevel nonvolatile analog memories and neuromorphic computing architectures. Reliable low energy performance and tunability of nonlinear resistive switching dynamics are essential to streamline the high‐density circuit level integration of these devices. Here, manipulation of room temperature‐synthesized defect chemistry is employed to enhance and tune the switching characteristics of high‐performance amorphous SrTiO3 (a‐STO) memristors. Substitutional donor (Nb) doping with low concentrations in the a‐STO oxide structure allows extensive improvements in energy requirements, stability, and controllability of the memristive performance, as well as field‐dependent multistate resistive switching. Evidence is presented that room temperature donor doping results in a modified insulator oxide where dislocation sites act as charge carrier modulators for low energy and multilevel operation. Finally, the performance of donor‐doped a‐STO‐based memristive nanodevices is showcased, with the possibility of mechanical modulation of the nonlinear memristive characteristics of these devices demonstrated. These results highlight the potential of donor‐doped a‐STO nanodevices for high‐density integration as analog memories and multifunctional alternative logic elements.
Performance and Quality Characterization of the Reference MNA Nonlinear Optical Molecular Crystal by Pockels Electrooptic Confocal Microscopy
Authors: Hajj Bassam , Melanson Stephane , Desforges Jean , Gauvin Serge , Chauvat Dominique , Zyss Joseph
Published: April 2015

The recently proposed Pockels linear electrooptical microscopy is being applied to a quality and performance characterization of the 2‐methyl‐4‐nitroaniline quadratic nonlinear optical molecular crystal down to confocal microscope resolution. Samples are grown between electrodes in single‐film format. The dominant electrooptic tensor coefficient is determined and the distribution of the electric field is mapped so as to characterize polycrystalline features. The Pockels polarization response is shown to provide a unique way to the unambiguous assignment of the principal dielectric axis in the case of a low symmetry crystal. Application toward weak electric‐field sensing at a local scale is demonstrated.
A Novel Phase of Li15Si4 Synthesized under Pressure
Authors: Zeng Zhidan , Zeng Qingfeng , Liu Nian , Oganov Artem R. , Zeng Qiaoshi , Cui Yi , Mao Wendy L.
Published: April 2015

Li15Si4, the only crystalline phase that forms during lithiation of the Si anode in lithium‐ion batteries, is found to undergo a structural transition to a new phase at 7 GPa. Despite the large unit cell of Li15Si4 (152 atoms in the unit cell), ab initio evolutionary metadynamics (using the USPEX code) successfully predicts the atomic structure of this new phase (β‐Li15Si4), which has an orthorhombic structure with an Fdd2 space group. In the new β‐Li15Si4 phase Si atoms are isolated by Li atoms analogous to the original cubic phase (α‐Li15Si4), whereas the atomic packing is more efficient owing to the higher SiLi coordination number and shorter SiLi, LiLi bonds. β‐Li15Si4 has substantially larger elastic moduli compared with α‐Li15Si4, and has a good electrical conductivity. As a result, β‐Li15Si4 has superior resistance to deformation and fracture under stress. The theoretical volume expansion of Si would decrease 25% if it transforms to β‐Li15Si4, instead of α‐Li15Si4, during lithiation. Moreover, β‐Li15Si4 can be recovered back to ambient pressure, providing opportunities to further investigate its properties and potential applications.
A Modular Approach to the Total Synthesis of Tunicamycins
Authors: Li Jiakun , Yu Biao
Published: April 2015

The tunicamycins constitute a delicate mimic of the bisubstrate intermediates of N‐acetyl‐D‐hexosamine‐1‐phosphate translocases and thus inhibit bacterial cell‐wall synthesis and the N glycosylation of eukaryotic proteins. An efficient approach to the synthesis of this unique type of nucleoside antibiotics is now reported and features the assembly of five modules in a highly stereoselective and robust manner. A Mukaiyama aldol reaction, intramolecular acetal formation, gold(I)‐catalyzed O and N glycosylation, and final N acylation were used as the key steps.
Metallophthalocyanine‐Based Conjugated Microporous Polymers as Highly Efficient Photosensitizers for Singlet Oxygen Generation
Authors: Ding Xuesong , Han Bao‐Hang
Published: April 2015

Singlet oxygen (1O2) is of great interest because of its potential applications in photodynamic therapy, photooxidation of toxic molecules, and photochemical synthesis. Herein, we report novel metallophthalocyanine (MPc) based conjugated microporous polymers (MPc‐CMPs) as photosensitizers for the generation of 1O2. The rigid microporous structure efficiently improves the exposure of the majority of the MPc units to oxygen. The MPc‐CMPs also exhibit an enhanced light‐harvesting capability in the far‐red region through their extended π‐conjugation systems. Their microporous structure and excellent absorption capability for long‐wavelength photons result in the MPc‐CMPs showing high efficiency for 1O2 generation upon irradiation with 700 nm light, as evident by using 1,3‐diphenylisobenzofuran as an 1O2 trap. These results indicate that MPc‐CMPs can be considered as promising photosensitizers for the generation of 1O2.
Design, Synthesis, and Pharmacological Evaluation of Highly Potent and Selective Dipeptidyl Peptidase‐4 Inhibitors
Authors: Jiang Tao , Zhou Yuren , Zhu Jianming , Chen Zhuxi , Sun Peng , Zhang Qiang , Wang Zhen , Shao Qiang , Jiang Xiangrui , Li Bo , Wang Heyao , Zhu Weiliang , Shen Jingshan
Published: April 2015

The optimization of a series of fused β‐homophenylalanine inhibitors of dipeptidyl peptidase‐4 (DPP‐4) is described. Modification on the P2‐binding moiety of 6 (IC50 = 10 nM) led to the discovery of β‐homophenylalanine derivatives containing pyrrolidin‐2‐ylmethyl amides. The introduction of a sulfamine in the meta position of the phenyl ring improved the potency against DPP‐4 (6–12‐fold increase). Compound 14k showed DPP‐4 inhibitory activity with an IC50 value of 0.87 nM. Meanwhile, in vivo experiments exhibited that 14h had an efficiency comparable to sitagliptin at the dose of 10 mg/kg.
Guns, Mental Illness, and the Law: Introduction to This Issue
Authors: Swanson Jeffrey W. , Felthous Alan R.
Published: April 2015

Firearm violence is a top‐tier public health problem in the U.S., killing 33,563 and injuring an additional 81,396 people in 2012 (Centers for Disease Control and Prevention, CDC, ). Given constitutional protection and the cultural entrenchment of private gun ownership in the U.S., it is likely that guns will remain widely accessible – and largely unrestricted – for the foreseeable future. Therefore, most policies and laws intended to reduce firearm violence focus selectively on preventing “dangerous people” from having access to guns. That is a formidable challenge. How do we think productively about guns and mental illness in this context, and about the role of law in lessening the toll of gun violence? Copyright © 2015 John Wiley & Sons, Ltd.
Retracted: Anatomy of the hip capsule and pericapsular structures: A cadaveric study
Authors: Cooper H. John , Walters Brian L. , Rodriguez José A.
Published: April 2015

The anatomical literature contains relatively little qualitative or quantitative information regarding the anatomy of the hip joint capsule and its relationship to the surrounding pericapsular structures. We aimed to provide a detailed description of the anatomy of these relationships in a cadaveric study. Dissections of 11 nonpaired, fresh‐frozen cadaveric hips were performed, documenting capsular dimensions and attachments to pericapsular structures including the rectus femoris, gluteus minimus, iliocapsularis, and piriformis and short external rotator muscles. Tendon footprints of these pericapsular muscles were measured, as well as their distance from reproducible bony landmarks. The thickest portion of the hip capsule is posterosuperiorly and superiorly near its acetabular origin, while the thinnest portion is posteriorly and posteroinferiorly near its femoral insertion. The piriformis has no capsular contribution; however, the reflected head of the rectus femoris, gluteus minimus, iliocapsularis, and external rotator tendons all demonstrate consistent capsular adhesions. There are complex associations among these structures, yet the surrounding layers of the capsule are confluent in predictable relationships. Knowledge of the intricate relationship between the hip capsule and pericapsular structures presented here will be useful for surgeons as they perform the precise and specific capsular releases required by various operative procedures. This study also provides information that can lead to further biomechanical, radiographic, and clinical studies on these structures. Clin. Anat. 28:665–671, 2015. © 2015 Wiley Periodicals, Inc.
Nonenzymatic Transformation of Amorphous CaCO3 into Calcium Phosphate Mineral after Exposure to Sodium Phosphate in Vitro: Implications for in Vivo Hydroxyapatite Bone Formation
Authors: Müller Werner E. G. , Neufurth Meik , Huang Jian , Wang Kui , Feng Qingling , Schröder Heinz C. , Diehl‐Seifert Bärbel , Muñoz‐Espí Rafael , Wang Xiaohong
Published: April 2015

Studies indicate that mammalian bone formation is initiated at calcium carbonate bioseeds, a process that is driven enzymatically by carbonic anhydrase (CA). We show that amorphous calcium carbonate (ACC) and bicarbonate (HCO3−) cause induction of expression of the CA in human osteogenic SaOS‐2 cells. The mineral deposits formed on the surface of the cells are rich in C, Ca and P. FTIR analysis revealed that ACC, vaterite, and aragonite, after exposure to phosphate, undergo transformation into calcium phosphate. This exchange was not seen for calcite. The changes to ACC, vaterite, and aragonite depended on the concentration of phosphate. The rate of incorporation of phosphate into ACC, vaterite, and aragonite, is significantly accelerated in the presence of a peptide rich in aspartic acid and glutamic acid. We propose that the initial CaCO3 bioseed formation is driven by CA, and that the subsequent conversion to calcium phosphate/calcium hydroxyapatite (exchange of carbonate by phosphate) is a non‐enzymatic exchange process.
Numerical Simulation of Interfacial Closures for 3D Bubble Column Flows
Authors: Masood Rao M. A. , Jovicic Vojislav , Delgado Antonio
Published: April 2015

Numerical investigation of flow hydrodynamics in a square cross‐sectioned bubble column was conducted in a transient Euler‐Euler environment by applying the simulation tool Ansys CFX 14.0. The influence of the drag coefficient (CD) was investigated and the results were also compared with drag force models. Furthermore, three different lift force models and a defined lift coefficient were studied. All results were compared with the available experimental data. All simulations were carried out for a single‐hole sparger with given aspect ratio (H/D) and superficial gas velocity.
Mathematical Modeling of a Simulated Moving‐Bed Adsorption Process: Parex™ Technology as a Case Study
Authors: Rezazadeh Mahdi , Esfahani Mohammad Seifi , Rahimi Amir , Ehsani Mohammad Reza
Published: April 2015

A simplified dynamic mathematical model for a simulated moving‐bed adsorption process is presented. The model is adopted to simulate the separation process of p‐xylene from the other 8‐carbon aromatics by means of the Parex™ technology. Operating conditions and the moving‐bed structure for a commercial plant were used and the performance of the unit was simulated. The model results are in good agreement with the findings of similar existing studies. Comparison of the results of this simplified model with those obtained by other researches indicates a considerable decrease in central processing unit (CPU) time.
Extraction of Spent Bleaching Earth in the Production of Renewable Diesel
Authors: Kuuluvainen Vilppu , Mäki‐Arvela Päivi , Eränen Kari , Holappa Anton , Hemming Jarl , Österholm Heidi , Toukoniitty Blanka , Murzin Dmitry Y.
Published: April 2015

The extraction of oils based on animal fat and vegetable oil from two types of spent bleaching earths, namely from the acidic sepiolite and the nonacidic palygorskite, was investigated by the Soxhlet method with hexane as a solvent. The yields of oil were independent of the feedstock, whereas a much lower oil yield was obtained with palygorskite exhibiting also a smaller surface area as compared to sepiolite which provided a higher yield. The glyceride compositions were very similar in bleached and extracted oils, while slightly lower melting and crystallization energies were determined by differential scanning calorimetry for the extracted oils bleached with acidic clay indicating minor hydrolysis of triglycerides.
Small Iminocoumarin Derivatives as Red Emitters: From Biological Imaging to Highly Photoluminescent Non‐doped Micro‐ and Nanofibres
Authors: Khemakhem Kacem , Soulié Marine , Brousses Rémy , Ammar Houcine , Abid Souhir , Fery‐Forgues Suzanne
Published: April 2015

The fluorescence properties of four derivatives of 3‐thienyl‐2‐(N‐dicyanovinyl)iminocoumarin, bearing a diethylamino group in the 7‐position or a methoxy group in the 6, 7 and 8 positions, were compared in solution and in the solid state. The 7‐diethylamino derivative was strongly fluorescent in various solvents, with marked solvatochromism. Its fluorescence was quenched by aggregation. In contrast, the methoxy derivatives were only moderately or weakly fluorescent in solution, but two of them were strongly photoluminescent in the crystalline state, owing to favourable molecular packing. The 6‐methoxy derivative even exhibited spectacular crystallization‐enhanced emission, examples of which are particularly rare for this type of dyes. Dyes were tested for biological use. The 7‐diethylamino derivative led to particularly strong fluorescence staining of the cytoplasm of HCT‐116 colon cancer cells. No fading was observed over prolonged illumination by the microscope light beam, but a phototoxic effect was detected. The use of the dyes as red‐emitting materials was also investigated. Using easy‐to‐implement preparation methods, the compounds self‐ assembled to give one‐dimensional nano‐ and microsized particles, including millimeter‐long microfibres that exhibited clear wave‐guiding properties. This study shows the value of these low molecular‐weight molecules for the preparation of new orange and red‐emitting fluorescent materials based on totally pure dye.
Plasticity of the Malleobactin Pathway and Its Impact on Siderophore Action in Human Pathogenic Bacteria
Authors: Franke Jakob , Ishida Keishi , Hertweck Christian
Published: April 2015

The human pathogenic bacteria Burkholderia mallei, Burkholderia pseudomallei, and Burkholderia thailandensis harbor a highly conserved gene cluster coding for the biosynthesis of the long sought‐after malleobactins. Four new, unexpected congeners of the malleobactin family that were isolated and fully characterized in this study feature unusual deviations from the parent, ornibactin‐like architecture. Thus, the malleobactin non‐ribosomal peptide synthetase (NRPS) has a rare flexibility that yields diverse peptide backbones, of which one candidate confers pronounced siderophore activity (EC50: 8.4 μM, CAS assay). These findings not only unveil a highly diverse assembly line but also are an important addition to the knowledgebase of the pathogens’ metabolomes.
[P3Se4]+: A Binary Phosphorus Selenium Cation
Authors: Feldmann K.‐O. , Wiegand T. , Ren J. , Eckert H. , Breternitz J. , Groh M. F. , Müller U. , Ruck M. , Maryasin B. , Ochsenfeld C. , Schön O. , Karaghiosoff K. , Weigand J. J.
Published: April 2015

Highlighted on the cover of this issue is a collaboration between the groups of Jan Weigand and Michael Ruck at TU Dresden, Hellmut Eckert and Thomas Wiegand at Westfälische Wilhelms‐University Münster, and Christian Ochsenfeld and Konstantin Karaghiosoff at Ludwig Maximilians University Munich (all Germany), who teamed up to uncover the novel selenium cation, [P3Se4]+. Three distinct syntheses and detailed information on its structural, electronic and dynamic properties resulted from the combination of the groups’ different perspectives (cover design by Dr. Kai‐Oliver Feldmann from the Weigand group). Read the full text of the article at 10.1002/chem.201406476.
Feasibility of Extended Ambulatory Electrocardiogram Monitoring to Identify Silent Atrial Fibrillation in High‐risk Patients: The Screening Study for Undiagnosed Atrial Fibrillation (STUDY‐AF)
Authors: Turakhia Mintu P. , Ullal Aditya J. , Hoang Donald D. , Than Claire T. , Miller Jared D. , Friday Karen J. , Perez Marco V. , Freeman James V. , Wang Paul J. , Heidenreich Paul A.
Published: April 2015

Background

Identification of silent atrial fibrillation (AF) could prevent stroke and other sequelae.

Hypothesis

Screening for AF using continuous ambulatory electrocardiographic (ECG) monitoring can detect silent AF in asymptomatic in patients with known risk factors.

Methods

We performed a single‐center prospective screening study using a wearable patch‐based device that provides up to 2 weeks of continuous ambulatory ECG monitoring (iRhythm Technologies, Inc.). Inclusion criteria were age ≥55 years and ≥2 of the following risk factors: coronary disease, heart failure, hypertension, diabetes, sleep apnea. We excluded patients with prior AF, stroke, transient ischemic attack, implantable pacemaker or defibrillator, or with palpitations or syncope in the prior year.

Results

Out of 75 subjects (all male, age 69 ± 8.0 years; ejection fraction 57% ± 8.7%), AF was detected in 4 subjects (5.3%; AF burden 28% ± 48%). Atrial tachycardia (AT) was present in 67% (≥4 beats), 44% (≥8 beats), and 6.7% (≥60 seconds) of subjects. The combined diagnostic yield of sustained AT/AF was 11%. In subjects without sustained AT/AF, 11 (16%) had ≥30 supraventricular ectopic complexes per hour.

Conclusions

Outpatient extended ECG screening for asymptomatic AF is feasible, with AF identified in 1 in 20 subjects and sustained AT/AF identified in 1 in 9 subjects, respectively. We also found a high prevalence of asymptomatic AT and frequent supraventricular ectopic complexes, which may be relevant to development of AF or stroke. If confirmed in a larger study, primary screening for AF could have a significant impact on public health.
Preoperative Cerebrovascular Evaluation in Patients With Infective Endocarditis
Authors: Behrouz Réza
Published: April 2015

Approximately 12% to 40% of infective endocarditis patients experience cerebrovascular complications. One of the major clinical challenges in cerebrovascular medicine is management of infective endocarditis patients with cerebrovascular complications who require valve operations. Cerebrovascular specialists are often summoned to address appropriate preoperative brain imaging, timing of surgery, and estimation of the risk of perioperative cerebral embolization and hemorrhage. This article addresses these issues based on the available evidence.
Effect of treatment and mammography detection on breast cancer survival over time: 1990‐2007
Authors: Kaplan Henry G. , Malmgren Judith A. , Atwood Mary K. , Calip Gregory S.
Published: April 2015

BACKGROUND

The extent to which improvements over time in breast cancer survival are related to earlier detection by mammography or to more effective treatments is not known.

METHODS

At a comprehensive cancer care center, the authors conducted a retrospective cohort study of women ages 50 to 69 years who were diagnosed with invasive breast cancer (stages I through III) and were followed over 3 periods (1990‐1994, 1995‐1999, and 2000‐2007). Data were abstracted from patient charts and included detection method, diagnosis, treatment, and follow‐up for vital status in the institutional breast cancer registry (n = 2998). The method of detection was categorized as patient or physician detected or mammography detected. Cox proportional hazards models were used to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for 5‐year disease‐specific survival in relation to detection method and treatment factors, and differences in survival were analyzed using the Kaplan‐Meier method.

RESULTS

Fifty‐eight percent of breast cancers were mammography detected, and 42% were patient or physician detected; 56% of tumors were stage I, 31% were stage II, and 13% were stage III. The average length of follow‐up was 10.71 years. The combined 5‐year disease‐specific survival rate was 89% from 1990 to 1994, 94% from 1995 to 1999, and 96% from 2000 to 2007 (P < .001). In an adjusted model, mammography detection (HR, 0.43; 95% CI, 0.27‐0.70), hormone therapy (HR, 0.47; 95% CI, 0.30‐0.75), and taxane‐containing chemotherapy (HR, 0.61; 95% CI, 0.37‐0.99) were significantly associated with a decreased risk of disease‐specific mortality.

CONCLUSIONS

Better breast cancer survival over time was related to mammography detection, hormone therapy, and taxane‐containing chemotherapy. Treatment improvements alone are not sufficient to explain the observed survival improvements over time. Cancer 2015;121:2553–2561. © 2015 American Cancer Society.
Characterizing the Intermediates Compound I and II in the Cytochrome P450 Catalytic Cycle with Nonlinear X‐ray Spectroscopy: A Simulation Study
Authors: Zhang Yu , Biggs Jason D. , Mukamel Shaul
Published: April 2015

Cytochrome P450 enzymes are an important family of biocatalysts that oxidize chemically inert CH bonds. There are many unresolved questions regarding the catalytic reaction intermediates, in particular P450 Compound I (Cpd‐I) and II (Cpd‐II). By using simple molecular models, we simulate various X‐ray spectroscopy signals, including X‐ray absorption near‐edge structure (XANES), resonant inelastic X‐ray scattering (RIXS), and stimulated X‐ray Raman spectroscopy (SXRS) of the low‐ and high‐spin states of Cpd‐I and II. Characteristic peak patterns are presented and connected to the corresponding electronic structures. These X‐ray spectroscopy techniques are complementary to more conventional infrared and optical spectroscopy and they help to elucidate the evolving electronic structures of transient species along the reaction path.
Molecular Modeling of Bioorganometallic Compounds: Thermodynamic Properties of Molybdocene–Glutathione Complexes and Mechanism of Peptide Hydrolysis
Authors: Suárez Dimas , Díaz Natalia
Published: April 2015

The computational study of bioinorganic complexes between transition metals and flexible ligands is still challenging, given that, besides requiring extensive conformational searches, the treatment of metal–ligand bonds demands the application of quantum chemical methods. Herein, the adducts formed between molybdocene, which exhibits antitumor activity and reacts with thiol groups to give stable water‐soluble complexes, and the tripeptide glutathione, which is a major source of biological thiols, are studied. Conformational searches are performed using the semiempirical PM6 method followed by geometry optimizations and single‐point calculations using density functional theory methods. In addition, molecular dynamics simulations of the molybdocene–glutathione complex involved in the regioselective hydrolysis of the Cys–Gly linkage are performed in explicit solvent. The reactive process is also studied theoretically on cluster models of both the molybdocene‐bound and the free peptide.
In Situ Catalytic Hydrogenation of Biomass‐Derived Methyl Levulinate to γ‐Valerolactone in Methanol
Authors: Tang Xing , Li Zheng , Zeng Xianhai , Jiang Yetao , Liu Shijie , Lei Tingzhou , Sun Yong , Lin Lu
Published: April 2015

In this work, the hydrocyclization of methyl levulinate (ML) to γ‐valerolactone (GVL) was performed in MeOH over an in situ prepared nanocopper catalyst without external H2. This nanocopper catalyst served as a dual‐functional catalyst for both hydrogen production by MeOH reforming and hydrogenation of ML. Nearly quantitative ML conversion with a GVL selectivity of 87.6 % was achieved at 240 °C in 1 h in MeOH under a nitrogen atmosphere. ML in the methanolysis products of cellulose also could be hydrogenated effectively to GVL over this nanocopper catalyst even in the presence of humins to give an ML conversion of 94.1 % and a GVL selectivity of 73.2 % at 240 °C in 4 h. The absorption behavior of humins on the surface of the nanocopper catalyst was observed, which resulted in a pronounced increase in the acidic sites of the nanocopper catalyst that facilitate ring‐opening and the hydrocarboxylation/alkoxycarbonylation of GVL to byproducts.
One‐step Conversion of Furfural into 2‐Methyltetrahydrofuran under Mild Conditions
Authors: Dong Fang , Zhu Yulei , Ding Guoqiang , Cui Jinglei , Li Xianqing , Li Yongwang
Published: April 2015

One‐step direct conversion of biomass‐derived furfural to 2‐methyltetrahydrofuran was realized under atmospheric pressure over a dual solid catalyst based on two‐stage‐packed Cu–Pd in a reactor; this is the first report that one‐step conversion of furfural resulted in high yield of 2‐methyltetrahydrofuran (97.1 %) under atmospheric pressure. This strategy provided a successive hydrogenation process, which avoids high H2 pressure, uses the reactor efficiently, and eliminates the product‐separation step. Therefore, it could enhance the overall efficiency as a result of low cost and high yield.
Determination of growth hormone releasing peptides metabolites in human urine after nasal administration of GHRP‐1, GHRP‐2, GHRP‐6, Hexarelin, and Ipamorelin
Authors: Semenistaya Ekaterina , Zvereva Irina , Thomas Andreas , Thevis Mario , Krotov Grigory , Rodchenkov Grigory
Published: April 2015

Growth hormone releasing peptides (GHRPs) stimulate secretion of endogenous growth hormone and are listed on the World Anti‐Doping Agency (WADA) Prohibited List. To develop an effective method for GHRPs anti‐doping control we have investigated metabolites of GHRP‐1, GHRP‐2, GHRP‐6, Hexarelin, and Ipamorelin in urine after nasal administration. Each compound was administrated to one volunteer. Samples were collected for 2 days after administration, processed by solid‐phase extraction on weak cation exchange cartridges and analyzed by means of nano‐liquid chromatography ‐ high resolution mass spectrometry. Six metabolites of GHRP‐1 were identified. GHRP‐1 in the parent form was not detected. GHRP‐1 (2‐4) free acid was detected in urine up to 27 h. GHRP‐2, GHRP‐2 free acid and GHRP‐2 (1‐3) free acid were detected in urine up to 47 h after administration. GHRP‐6 was mostly excreted unchanged and detected in urine 23 h after administration, its metabolites were detectable for 12 h only. Hexarelin and Ipamorelin metabolized intensively and were excreted as a set of parent compounds with metabolites. Hexarelin (1‐3) free acid and Ipamorelin (1‐4) free acid were detected in urine samples after complete withdrawal of parent substances. GHRPs and their most prominent metabolites were included into routine ultra‐pressure liquid chromatography‐tandem mass spectrometry procedure. The method was fully validated, calibration curves of targeted analytes were obtained and excretion curves of GHRPs and their metabolites were plotted. Our results confirm that the detection window after GHRPs administration depends on individual metabolism, drug preparation form and the way of administration. Copyright © 2015 John Wiley & Sons, Ltd.
Local and global pyrogeographic evidence that indigenous fire management creates pyrodiversity
Authors: Trauernicht Clay , Brook Barry W. , Murphy Brett P. , Williamson Grant J. , Bowman David M. J. S.
Published: April 2015

Despite the challenges wildland fire poses to contemporary resource management, many fire‐prone ecosystems have adapted over centuries to millennia to intentional landscape burning by people to maintain resources. We combine fieldwork, modeling, and a literature survey to examine the extent and mechanism by which anthropogenic burning alters the spatial grain of habitat mosaics in fire‐prone ecosystems. We survey the distribution ofCallitris intratropica, a conifer requiring long fire‐free intervals for establishment, as an indicator of long‐unburned habitat availability under Aboriginal burning in the savannas of Arnhem Land. We then use cellular automata to simulate the effects of burning identical proportions of the landscape under different fire sizes on the emergent patterns of habitat heterogeneity. Finally, we examine the global extent of intentional burning and diversity of objectives using the scientific literature. The current distribution ofCallitrisacross multiple field sites suggested long‐unburnt patches are common and occur at fine scales (<0.5 ha), while modeling revealed smaller, patchy disturbances maximize patch age diversity, creating a favorable habitat matrix forCallitris. The literature search provided evidence for intentional landscape burning across multiple ecosystems on six continents, with the number of identified objectives ranging from two to thirteen per study. The fieldwork and modeling results imply that the occurrence of long‐unburnt habitat in fire‐prone ecosystems may be an emergent property of patch scaling under fire regimes dominated by smaller fires. These findings provide a model for understanding how anthropogenic burning alters spatial and temporal aspects of habitat heterogeneity, which, as the literature survey strongly suggests, warrant consideration across a diversity of geographies and cultures. Our results clarify how traditional fire management shapes fire‐prone ecosystems, which despite diverse objectives, has allowed human societies to cope with fire as a recurrent disturbance.
Elevation as a barrier: genetic structure for an Atlantic rain forest tree (Bathysa australis) in the Serra do Mar mountain range, SE Brazil
Authors: Reis Talita Soares , Ciampi‐Guillardi Maísa , Bajay Miklos Maximiliano , de Souza Anete Pereira , dos Santos Flavio Antonio Maës
Published: April 2015

Distance and discrete geographic barriers play a role in isolating populations, as seed and pollen dispersal become limited. Nearby populations without any geographic barrier between them may also suffer from ecological isolation driven by habitat heterogeneity, which may promote divergence by local adaptation and drift. Likewise, elevation gradients may influence the genetic structure and diversity of populations, particularly those marginally distributed. Bathysa australis (Rubiaceae) is a widespread tree along the elevation gradient of the Serra do Mar, SE Brazil. This self‐compatible species is pollinated by bees and wasps and has autochoric seeds, suggesting restricted gene dispersal. We investigated the distribution of genetic diversity in six B. australis populations at two extreme sites along an elevation gradient: a lowland site (80–216 m) and an upland site (1010–1100 m.a.s.l.). Nine microsatellite loci were used to test for genetic structure and to verify differences in genetic diversity between sites. We found a marked genetic structure on a scale as small as 6 km (FST = 0.21), and two distinct clusters were identified, each corresponding to a site. Although B. australis is continuously distributed along the elevation gradient, we have not observed a gene flow between the extreme populations. This might be related to B. australis biological features and creates a potential scenario for adaptation to the different conditions imposed by the elevation gradient. We failed to find an isolation‐by‐distance pattern; although on the fine scale, all populations showed spatial autocorrelation until ~10‐20 m. Elevation difference was a relevant factor though, but we need further sampling effort to check its correlation with genetic distance. The lowland populations had a higher allelic richness and showed higher rare allele counts than the upland ones. The upland site may be more selective, eliminating rare alleles, as we did not find any evidence for bottleneck.
An Iron‐Based Photosensitizer with Extended Excited‐State Lifetime: Photophysical and Photovoltaic Properties
Authors: Duchanois Thibaut , Etienne Thibaud , Cebrián Cristina , Liu Li , Monari Antonio , Beley Marc , Assfeld Xavier , Haacke Stefan , Gros Philippe C.
Published: April 2015

Herein, we report a homoleptic iron complex bearing tridentate bis‐carbene (CNC) ligands designed for sensitization of TiO2 photoanodes. Its excited state has been characterized by ultra‐fast transient spectroscopy and time‐dependent density functional theory (TD‐DFT) computations, which reveal a record triplet metal‐to‐ligand charge‐transfer (3MLCT) excited‐state lifetime (16 ps). The new dye was efficiently chemisorbed on TiO2 and promoted electron injection and photocurrent generation in a dye‐sensitized solar cell upon solar irradiation.
Hg5AsS2I3 – A Narrow‐Band‐Gap 2D Layered Compound with Different Trapped I– Anions
Authors: Liu Yong , Zeng Hui‐Yi , Liu Bin‐Wen , Wang Geng‐E , Guo Guo‐Cong
Published: April 2015

A new layered compound, Hg5AsS2I3, has been synthesized in the quaternary system mercury/arsenic/chalcogen/halogen by a moderate‐temperature solid‐state reaction. The compound crystallizes in the space group C2/c of the monoclinic system, and its structure consists of ∞1[Hg(1)2Hg(2)2As2/2S2] eight‐membered‐ring chains bridged by Hg atoms to form [Hg(1)2Hg(2)2Hg(3)As2/2S2] layers with inner‐ and interlayer electrostatic interactions between I and Hg. The optical properties were investigated by means of diffuse reflectance and FTIR spectra. The electronic band structures, along with density of states (DOS) calculations by DFT, indicate that the title compound is a semiconductor, and its optical absorption mainly leads to charge transitions from I‐5p, As‐4p and S‐3p states to Hg‐6s states, and both I(1) and I(2) atoms contribute to the top of the valence bands.
Effects of diet supplementation with chia (Salvia hispanica L.) oil and natural antioxidant extract on the omega‐3 content and antioxidant capacity of Nile tilapia fillets
Authors: Montanher Paula Fernandes , Costa e Silva Beatriz , Bonafé Elton Guntendorfer , Carbonera Fabiana , dos Santos Hevelyse Munise Celestino , de Lima Figueiredo Ingrid , Maruyama Swami Arêa , Matsushita Makoto , Visentainer Jesuí Vergílio
Published: April 2015

In this study, the effect of adding chia oil and avocado extract to the diet of Nile tilapias (Oreochromis niloticus) was evaluated after 0, 15, 30 and 45 treatment days. The inclusion of chia oil and avocado extract aims to nutritional enrichment of fish fillet by the use of a new lipid source and a by‐product of low cost and high antioxidant capacity. Thus, experimental diets were formulated by the addition of 0.14% of ethanolic extract of avocado peel (Treatment I), 1.90% of chia (Salvia hispanica L.) oil (Treatment II) or both (0.14 and 1.90%, respectively) for Treatment III. There was an increase in the total omega‐3 (n‐3) fatty acid content of fish muscle tissue (29.01–78.81 mg g−1 TL) due to Treatment II (TII). Among n‐3 fatty acids, the amount of alpha‐linolenic acid (LNA, 18:3n‐3) increased sixfold after 45 days of feeding with the TII diet. The largest increases in antioxidant capacity were observed in the lipophilic fraction (L‐ORAC(FL)), from 3.40 to 19.50 μmol of ET g−1 from fish treated with chia oil (TII), while differences between treatments and periods were not detected in the hydrophilic fractions (H‐ORAC(FL)), indicating that excessive amounts of antioxidant compounds are simply excreted by the animals. Thus, chia oil contributed to an enhancement in the nutritional quality of Nile tilapia, both in terms of fatty acid content and total antioxidant capacity.

Practical applications: Multiple recent studies have emphasised the benefits to human health of including omega‐3 fatty acids and antioxidants in the diet. For this reason, the inclusion of chia (S. hispanica L.) oil and avocado (peel) residue was proposed in order to increase the amount of omega‐3 fatty acids in tilapia fillets and to improve muscle tissue antioxidant capacity. It is notable that these parameters increased significantly, especially the quantity of omega‐3 fatty acids, after a 45‐day trial, providing a differentiated product with a high nutritional quality.

From the addition of chia seed oil in rations, it was observed a significant increase of alpha‐linolenic content in tilapia fillets. The effects of supplemented feeding were more pronounced until 30 days. For antioxidant compound analysis, in most of the cases, better results were observed from L‐ORAC(FL) assay. Thus, the fish which received rations supplemented with chia seed oil showed a superior nutritional quality, especially in terms of fatty acid composition.