bluuebunny/crossref_metadata_2025 huggingface dataset:
Safety instrumented systems in lieu of pressure relief valves
Authors: Smith Dustin J.
Published: June 2014

There are two aspects to risk assessments: safety issues and regulatory issues. Usually the two are aligned, but not always. This article explains ASME B&PVC Section VIII (Sec VIII) [American Society of Mechanical Engineers, 2013 ASME Boiler & Pressure Vessel Code: Section VIII, Division I. s.l.] requirements along with other industry guidance for using Safety Instrumented Systems (SIS) in lieu of pressure relief devices (e.g., pressure relief valves or rupture disks). For most pressure vessels in petrochemical installations in the United States, the Sec VIII requirements are regulatory requirements. A designer that is implementing facility changes from a corporate risk assessment (e.g., Layer of Protection Analysis or Hazard and Operability Study (HAZOP)) would do well to also meet the minimum regulatory requirements for overpressure in Sec VIII. Typical risk assessments allow the designer to consider both the likelihood and consequences of an overpressure scenario in determining if additional mitigation is required. Whereas, Sec VIII does not allow any credible overpressure scenarios (solely based on likelihood) unless there is adequate capacity provided by a relief device. This article discusses the detailed typical risk analysis compared to the requirements of Sec VIII overpressure protection by system design. The SIS reliability rating or determination of said rating (e.g., SIL‐3 Systems) is outside the scope of this article. © 2014 American Institute of Chemical Engineers Process Saf Prog 33: 345–349, 2014
On the design of supramolecular assemblies made of peptides and lipid bilayers
Authors: Kemayo Koumkoua Patricia , Aisenbrey Christopher , Salnikov Evgeniy , Rifi Omar , Bechinger Burkhard
Published: June 2014

Peptides confer interesting properties to materials, supramolecular assemblies and to lipid membranes and are used in analytical devices or within delivery vehicles. Their relative ease of production combined with a high degree of versatility make them attractive candidates to design new such products. Here, we review and demonstrate how CD‐ and solid‐state NMR spectroscopic approaches can be used to follow the reconstitution of peptides into membranes and to describe some of their fundamental characteristics. Whereas CD spectroscopy is used to monitor secondary structure in different solvent systems and thereby aggregation properties of the highly hydrophobic domain of p24, a protein involved in vesicle trafficking, solid‐state NMR spectroscopy was used to deduce structural information and the membrane topology of a variety of peptide sequences found in nature or designed. 15N chemical shift solid‐state NMR spectroscopy indicates that the hydrophobic domain of p24 as well as a designed sequence of 19 hydrophobic amino acid residues adopt transmembrane alignments in phosphatidylcholine membranes. In contrast, the amphipathic antimicrobial peptide magainin 2 and the designed sequence LK15 align parallel to the bilayer surface. Additional angular information is obtained from deuterium solid‐state NMR spectra of peptide sites labelled with 2H3‐alanine, whereas 31P and 2H solid‐state NMR spectra of the lipids furnish valuable information on the macroscopic order and phase properties of the lipid matrix. Using these approaches, peptides and reconstitution protocols can be elaborated in a rational manner, and the analysis of a great number of peptide sequences is reviewed. Finally, a number of polypeptides with membrane topologies that are sensitive to a variety of environmental conditions such as pH, lipid composition and peptide‐to‐lipid ratio will be presented. Copyright © 2014 European Peptide Society and John Wiley & Sons, Ltd.
Telomere length regulation in budding yeasts
Authors: Malyavko Alexander N. , Parfenova Yuliya Y. , Zvereva Maria I. , Dontsova Olga A.
Published: June 2014

Telomeres are the nucleoprotein caps of chromosomes. Their length must be tightly regulated in order to maintain the stability of the genome. This is achieved by the intricate network of interactions between different proteins and protein–RNA complexes. Different organisms use various mechanisms for telomere length homeostasis. However, details of these mechanisms are not yet completely understood. In this review we have summarized our latest achievements in the understanding of telomere length regulation in budding yeasts.
N‐glycosylation is required for secretion and enzymatic activity of human hyaluronidase1
Authors: Goto Yuki , Niwa Yuki , Suzuki Takehiro , Uematsu Shiho , Dohmae Naoshi , Simizu Siro
Published: June 2014

Hyaluronidase1 (HYAL1) is a hydrolytic enzyme that degrades hyaluronic acid (HA) and has three predicted N‐glycosylation sites at Asn99, Asn216, and Asn350. In this report, we show the functional significance of N‐glycosylation on HYAL1 functions. Using mass spectrometry, we demonstrated that HYAL1 was N‐glycosylated at the three asparagine residues. N‐glycosylation of HYAL1 is important for secretion of HYAL1, as demonstrated by site‐directed mutation. Moreover, a defect of N‐glycosylation attenuated the enzymatic activity of HYAL1. Thus, HYAL1 is N‐glycosylated at the three asparagine residues, and its secretion and enzymatic activity are regulated by N‐glycosylation.
Onset of aquaporin‐4 expression in the developing mouse brain
Authors: Fallier‐Becker Petra , Vollmer Jörg P. , Bauer Hans‐C. , Noell Susan , Wolburg Hartwig , Mack Andreas F.
Published: June 2014

The main water channel in the brain, aquaporin‐4 (AQP4) is involved in maintaining homeostasis and water exchange in the brain. In adult mammalian brains, it is expressed in astrocytes, mainly, and in high densities in the membranes of perivascular and subpial endfeet. Here, we addressed the question how this polarized expression is established during development. We used immunocytochemistry against AQP4, zonula occludens protein‐1, glial fibrillary acidic protein, and β‐dystroglycan to follow astrocyte development in E15 to P3 NMRI mouse brains, and expression of AQP4. In addition we used freeze‐fracture electron microscopy to detect AQP4 in the form of orthogonal arrays of particles (OAPs) on the ultrastructural level.

We analyzed ventral, lateral, and dorsal regions in forebrain sections and found AQP4 immunoreactivity to emerge at E16 ventrally before lateral (E17) and dorsal (E18) areas. AQP4 staining was spread over cell processes including radial glial cells in developing cortical areas and became restricted to astroglial endfeet at P1–P3. This was confirmed by double labeling with GFAP. In freeze‐fracture replicas OAPs were found with a slight time delay but with a similar ventral to dorsal gradient. Thus, AQP4 is expressed in the embryonic mouse brain starting at E16, earlier than previously reported. However a polarized expression necessary for homeostatic function and water balance emerges at later stages around and after birth.
Evolution of ventricular tachycardia ablation in structural heart disease
Authors: Tung Roderick
Published: June 2014

The field of catheter ablation of VT has evolved conceptually and technologically over the past three decades. From the fundamental understanding of the reentrant mechanism in scar‐mediated VT to the advent and routine implementation of electroanatomic mapping, catheter ablation has emerged from a palliative last‐resort therapy to a more preemptive strategy for patients at risk for arrhythmia recurrence. An increasing utilization of pre‐procedural imaging, high‐density mapping, epicardial access, and more extensive ablation strategies have all contributed to improved clinical success. Advances in ablation technology and randomized trials are needed to build upon the progress in this growing field as sudden cardiac death from ventricular tachyarrhythmia continues to be the one of leading causes of death throughout the world.
Catheter ablation of epicardial ventricular tachycardia
Authors: Yamada Takumi
Published: June 2014

Ventricular tachycardias (VTs) can usually be treated by endocardial catheter ablation. However, some VTs can arise from the epicardial surface, and their substrate can be altered only by epicardial catheter ablation. There are two approaches to epicardial catheter ablation: transvenous and transthoracic. The transvenous approach through the coronary venous system (CVS) has been commonly used because it is easily accessible. However, this approach may be limited by the distribution of the CVS and insufficient radiofrequency energy delivery. Transthoracic epicardial catheter ablation has been developed to overcome these limitations of the transvenous approach. It is a useful supplemental or even preferred strategy to eliminate epicardial VTs in the electrophysiology laboratory. This technique has been applied for scar‐related VTs secondary to often non‐ischemic cardiomyopathy and sometimes ischemic cardiomyopathy, and idiopathic VTs as the epicardial substrates of these VTs have become increasingly recognized. When endocardial ablation and epicardial ablation through the CVS are unsuccessful, transthoracic epicardial ablation should be the next option. Intrapericardial access is usually obtained through a subxiphoidal pericardial puncture. This approach might not be possible in patients with pericardial adhesions caused by prior cardiac surgery or pericarditis. In such cases, a hybrid procedure involving surgical access with a subxiphoid pericardial window and a limited anterior or lateral thoracotomy might be a feasible and safe method of performing an epicardial catheter ablation in the electrophysiology laboratory. Potential complications associated with this technique include bleeding and collateral damage to the coronary arteries and phrenic nerve. Although the risk of these complications is low, electrophysiologists who attempt epicardial catheter ablation should know the complications associated with this technique, how to minimize their occurrence, and how to rapidly recognize and treat the complications that they encounter. This review discusses the indications, techniques, and complications of the transvenous and transthoracic epicardial catheter ablation of VTs.
OSCAR – ein internetbasiertes Unterstützungsprogramm für Angehörige von Menschen mit einer Hirnverletzung: Pilotstudie
Authors: Frischknecht Eveline , Berger Thomas , Stalder-Lüthy Franziska , Znoj Hansjörg , Hofer Helene
Published: June 2014

Erhöhte Depressivität und Ängstlichkeit sowie ein erhöhtes subjektives Belastungserleben sind bei Angehörigen von Menschen mit einer Hirnverletzung häufig. Die vorliegende Pilotuntersuchung widmet sich der Evaluation einer neuartigen Intervention, dem OSCAR Online-Coaching, einer internetbasierten Mehrkomponentenintervention. In einer randomisierten, kontrollierten Pilotstudie mit 35 TeilnehmerInnen wurde ein 16-wöchiges therapeutengeleitetes Selbsthilfeprogramm mit einer Wartekontrollgruppe verglichen. Als primäre Ergebnismasse wurde der Perceived Stress Questionnaire und das Zarit Burden Interview eingesetzt. Intention-to-treat-Analysen der unmittelbaren Effekte direkt nach der Intervention zeigten keine signifikanten Gruppenunterschiede auf den primären und auf sekundären Ergebnismassen. Im 6-Monate Follow-up, nach Zugang der Kontrollgruppe zur Intervention, wurde in der Gesamtstichprobe eine signifikante Reduktion des Caregiver Burden, depressiver Symptome, der Angst, sowie eine Zunahme positiver Emotionen gefunden. Die Zufriedenheit mit dem Programm war gut.
Die Rezeption systemischer Denk- und Therapieansätze für die klinische Neuropsychologie
Authors: Nielsen Jörn
Published: June 2014

In den Naturwissenschaften hat durch die Systemtheorie und die Berücksichtigung von Komplexität, Zirkularität und Prozessualität seit langem ein Paradigmenwechsel stattgefunden. Dieses systemtheoretische Denken bildet das Fundament der heutigen Systemischen Therapie (ST). Ihr besonderes Merkmal ist die Einbeziehung des interaktionellen Kontextes unter Beachtung unterschiedlicher Systemebenen (Patient, Familie, Behandlungsteam usw.). Das Aufgabengebiet der klinischen Neuropsychologie umfasst wiederum nicht nur die Diagnostik und Therapie gestörter Hirnfunktionen, sondern der „gesamte Patient” und seine Angehörigen stehen im Behandlerfokus; dies erfordert ein entsprechend aufgestelltes Interventionsrepertoire. Gemäß Autorenmeinung kann die ST diesen „neuropsychologischen Behandlungskoffer” mit ihrem Grundverständnis, ihrer Haltung und ihrem Methodenspektrum bereichern. Im Blickpunkt stehen dabei die „kommunikativen Spielregeln” (Sinndeutungen, Sprache, Interaktionsmuster, Rollenverteilungen), die infolge eines Krankheitsereignisses bei Patienten, Angehörigen und Rehabilitationsteam „systemdynamisch” verändert sein können.
Die Standardabweichung der Reaktionszeiten als ein Maß für negative Antwortverzerrungen
Authors: Bodenburg Sebastian
Published: June 2014

Negative Antwortverzerrungen werden quantitativ mit expliziten Beschwerdenvalidierungstests oder mit eingebetteten Parametern untersucht. Es wird die Kriteriumsvalidität der Standardabweichung von Reaktionszeiten als eingebetteter Parameter zur Untersuchung negativer Antwortverzerrungen überprüft. In die Studie wurden 26 Frauen und 65 Männer mit Schädelhirnverletzungen einbezogen. Abhängige Variable war die Standardabweichung der Reaktionszeiten (Untertest Alertness, Testbatterie zur Aufmerksamkeitsprüfung). Prädiktorvariablen in der multivariaten Kovarianzanalyse waren das Alter der Probanden und folgende Testrohwerte: Trail Making Test (Formen A und B), Parameter GSI der Symptomcheckliste, Untertest Zahlennachsprechen vorwärts aus der Wechsler Memory Scale, Strukturierter Fragebogen Simulierter Symptome, der mittlere Wert der in Prozentzahlen ausgedrückten richtigen Antworten der Parameter IR, DR und CNS des Word Memory Tests (WMT), das Geschlecht der Probanden sowie die dichotomisierte Gruppierung von Patienten mit oder ohne klinisch fassbaren Auffälligkeiten der Aufmerksamkeit. Von den Prädiktorvariablen stellte sich allein der mittlere Wert der in Prozent ausgedrückten richtigen Antworten des WMT als signifikant heraus. Probanden mit einer geringen Anzahl richtiger Antworten im WMT zeigten größere Standardabweichungen. Alle weiteren einbezogenen Prädiktoren – insbesondere beide Aufmerksamkeitsparameter – hatten in Bezug auf die Standardabweichungen keinen signifikanten Einfluss.
Heterogeneous copper-catalyzed hydroxylation of aryl iodides under air conditions
Authors: Ding Guodong , Han Hongling , Jiang Tao , Wu Tianbin , Han Buxing
Published: June 2014

The synthesis of ligand-free heterogeneous copper-catalyzed phenols through the hydroxylation of aryl iodides using cheap bases under air conditions was reported.
Mussel-inspired, perfluorinated polydopamine for self-cleaning coating on various substrates
Authors: Hong Daewha , Bae KiEun , Hong Seok-Pyo , Park Ji Hun , Choi Insung S. , Cho Woo Kyung
Published: June 2014

Substrate-independent coating for self-cleaning, superhydrophobic surfaces was achieved by oxidative polymerization of a mussel-inspired dopamine derivative (f-DOPA).
A complex of poly(4-vinylpyridine) and tolane based hemi-phasmid benzoic acid: towards luminescent supramolecular side-chain liquid crystalline polymers
Authors: Wang Shao-Jie , Zhao Rui-Ying , Yang Shuang , Yu Zhen-Qiang , Chen Er-Qiang
Published: June 2014

A luminescent supramolecular polymer based on P4VP and a tolane based hemi-phasmid benzoic acid forms Sm and Colh phases at different compositions and the luminescent properties depend on the phase structures.
Excited state proton transfer dynamics of an eminent anticancer drug, ellipticine, in octyl glucoside micelle
Authors: Gavvala Krishna , Koninti Raj Kumar , Sengupta Abhigyan , Hazra Partha
Published: June 2014

Prototropical and photophysical properties of an anticancer drug, ellipticine, are explored inside the octyl-β-d-glucoside micelles using steady state and time-resolved fluorescence spectroscopic techniques.
Synthesis and luminescence resonance energy transfer based on noble metal nanoparticles and the NaYF4:Tb3+ shell
Authors: Song Yan , Liu Guixia , Wang Jinxian , Dong Xiangting , Yu Wensheng
Published: June 2014

The hybrid core–shell nanostructure of Au/Ag@NaYF4:Tb3+ is constructed. In such LRET system, the highly efficient LRET is dependent on the extent of spectral overlap between the different transitions of the Tb3+ ion and noble nanoparticles.
Highly durable hydrophobicity in simulated space environment
Authors: Guo Ruisheng , Hu Haiyuan , Liu Zhilu , Wang Xiaolong , Zhou Feng
Published: June 2014

Perfluoropolyether-infused porous anodic alumina maintains superhydrophobicity durably under simulated space irradiations at low earth orbit (LEO).
Synthesis and self-assembly behavior of organic–inorganic macrocyclic molecular brushes composed of macrocyclic oligomeric silsesquioxane and poly(N-isopropylacrylamide)
Authors: Yi Yulin , Zheng Sixun
Published: June 2014

Macrocyclic molecular brushes composed of macrocyclic oligomeric silsesquioxanes and poly(N-isopropylacrylamide) were synthesized via the ATRP approach; they displayed self-assembly behavior.
The fast C(3P) + CH3OH reaction as an efficient loss process for gas-phase interstellar methanol
Authors: Shannon Robin J. , Cossou Christophe , Loison Jean-Christophe , Caubet Philippe , Balucani Nadia , Seakins Paul W. , Wakelam Valentine , Hickson Kevin M.
Published: June 2014

The reaction between ground state atomic carbon and methanol is shown to be an efficient destruction mechanism for interstellar methanol.
Polymer-controlled core–shell nanoparticles: a novel strategy for sequential drug release
Authors: Cao Yang , Wang Bochu , Wang Yazhou , Lou Deshuai
Published: June 2014

Immiscible and miscible liquids were utilized to fabricate PVP/PLGA and PCL/PLGA nanoparticles with a distinct core–shell structure by coaxial electrospray. Two different sequential drug release profiles from different nanoparticles were observed. The melanoma cells and endothelial cells can be sequentially targeted and killed by therapeutic agents released from nanoparticles.
Homogenization limit for a multiband effective mass model in heterostructures
Authors: Morandi O.
Published: June 2014

We study the homogenization limit of a multiband model that describes the quantum mechanical motion of an electron in a quasi-periodic crystal. In this approach, the distance among the atoms that constitute the material (lattice parameter) is considered a small quantity. Our model include the description of materials with variable chemical composition, intergrowth compounds, and heterostructures. We derive the effective multiband evolution system in the framework of the kp approach. We study the well posedness of the mathematical problem. We compare the effective mass model with the standard kp models for uniform and non-uniforms crystals. We show that in the limit of vanishing lattice parameter, the particle density obtained by the effective mass model, converges to the exact probability density of the particle.
Construction of dynamics and time-ordered exponential for unbounded non-symmetric Hamiltonians
Authors: Futakuchi Shinichiro , Usui Kouta
Published: June 2014

We prove under certain assumptions that there exists a solution of the Schrödinger or the Heisenberg equation of motion generated by a linear operator H acting in some complex Hilbert space \documentclass[12pt]{minimal}\begin{document}$\displaystyle \mathcal {H}$\end{document}H, which may be unbounded, not symmetric, or not normal. We also prove that, under the same assumptions, there exists a time evolution operator in the interaction picture and that the evolution operator enjoys a useful series expansion formula. This expansion is considered to be one of the mathematically rigorous realizations of so-called “time-ordered exponential,” which is familiar in the physics literature. We apply the general theory to prove the existence of dynamics for the mathematical model of Quantum Electrodynamics quantized in the Lorenz gauge, the interaction Hamiltonian of which is not even symmetric or normal.
Recommended Correlations for the Surface Tension of Several Fluids Included in the REFPROP Program
Authors: Mulero A. , Cachadiña I.
Published: June 2014

Accurate correlations are given for the temperature dependence of the surface tension of 37 fluids included in NIST's REFPROP program. The surface tension of these fluids was not included in the most recent version of this program, V9.12. A set of data was constructed for each of these fluids by including principally the values given in the DIPPR, DETHERM, and TDE databases and Wohlfarth and Wohlfarth's book. For some fluids, other available sources of data were added in order to obtain adequate sets. The correlation expression used is the same as used for other fluids in REFPROP. For 31 fluids it was enough to use two adjustable coefficients, whereas four coefficients were needed for the other 6 fluids. For 19 fluids, the mean average percentage deviation was below 1%, and for another 16 it ranged from 1% to 2%.
Efficient implementation of the three-dimensional reference interaction site model method in the fragment molecular orbital method
Authors: Yoshida Norio
Published: June 2014

The three-dimensional reference interaction site model (3D-RISM) method was efficiently implemented in the fragment molecular orbital (FMO) method. The method is referred to as the FMO/3D-RISM method, and allows us to treat electronic structure of the whole of a macromolecule, such as a protein, as well as the solvent distribution around a solute macromolecule. The formalism of the FMO/3D-RISM method, for the computationally available form and variational expressions, are proposed in detail. A major concern leading to the implementation of the method was decreasing the computational costs involved in calculating the electrostatic potential, because the electrostatic potential is calculated on numerous grid points in three-dimensional real space in the 3D-RISM method. In this article, we propose a procedure for decreasing the computational costs involved in calculating the electrostatic potential in the FMO method framework. The strategy involved in this procedure is to evaluate the electrostatic potential and the solvated Fock matrix in different manners, depending on the distance between the solute and the solvent. The electrostatic potential is evaluated directly in the vicinity of the solute molecule by integrating the molecular orbitals of monomer fragments of the solute molecule, whereas the electrostatic potential is described as the sum of multipole interactions when an analog of the fast multipole method is used. The efficiency of our method was demonstrated by applying it to a water trimer system and three biomolecular systems. The FMO/3D-RISM calculation can be performed within a reasonable computational time, retaining the accuracy of some physical properties.
The effect of hydrogen bonds on diffusion mechanism of water inside single-walled carbon nanotubes
Authors: Chen Qu , Wang Qi , Liu Ying-Chun , Wu Tao
Published: June 2014

Nanopores can serve as a molecule channel for transport of fluid, where water diffusion differs remarkably from that of simple particles. Hydrogen bonds play an essential role in the diffusion anomaly. Detailed investigations are carried out on the systems of rigid (6, 6), (7, 7), (8, 8), (9, 9), and (10, 10) armchair carbon nanotubes, solvated with Lennard-Jones water fluids. The role of hydrogen bonds is examined by diffusivity statistics and animation snapshots. It is found that in small (6,6) CNT, hydrogen bonds tend to aggregate water into a wire and lead to rapid collective drift. Confinement can stabilize the hydrogen bond of water molecules and enhance its lifetime. In relatively smaller CNTs, the diffusion mechanism could be altered by the temperature. Moreover, in larger nanotubes hydrogen bonding network allows the water to form regional concentrated clusters. This allows water fluid in extremely low density exhibit rather slow self-diffusion motion. This fundamental study attempts to provide insights in understanding nanoscale delivery system in aqueous solution.
An investigation into low-lying electronic states of HCS2 via threshold photoelectron imaging
Authors: Qin Zhengbo , Cong Ran , Liu Zhiling , Xie Hua , Tang Zichao , Fan Hongjun
Published: June 2014

Low-energy photoelectron imaging spectra of HCS2− are reported for the first time. Vibrationally resolved photodetachment transitions from the ground state of HCS2− to the ground state and low-lying excited states of HCS2 are observed. Combined with the ab intio calculations and Franck-Condon simulations, well-resolved vibrational spectra demonstrate definitive evidence for the resolution of the ground-state and excited states of HCS2 radical in the gaseous phase. The ground state and two low-lying excited states of HCS2 radical are assigned as 2B2, 2A2, and 2A1 states, respectively. The adiabatic electron affinity is determined to be 2.910 ± 0.007 eV. And the term energies of the excited states, T0 = 0.451 ± 0.009 eV and 0.553 ± 0.009 eV, are directly measured from the experimental data, respectively. Angular filtering photoelectron spectra are carried out to assist in the spectral band assignment.
Stochastic interactions of two Brownian hard spheres in the presence of depletants
Authors: Karzar-Jeddi Mehdi , Tuinier Remco , Taniguchi Takashi , Fan Tai-Hsi
Published: June 2014

A quantitative analysis is presented for the stochastic interactions of a pair of Brownian hard spheres in non-adsorbing polymer solutions. The hard spheres are hypothetically trapped by optical tweezers and allowed for random motion near the trapped positions. The investigation focuses on the long-time correlated Brownian motion. The mobility tensor altered by the polymer depletion effect is computed by the boundary integral method, and the corresponding random displacement is determined by the fluctuation-dissipation theorem. From our computations it follows that the presence of depletion layers around the hard spheres has a significant effect on the hydrodynamic interactions and particle dynamics as compared to pure solvent and uniform polymer solution cases. The probability distribution functions of random walks of the two interacting hard spheres that are trapped clearly shift due to the polymer depletion effect. The results show that the reduction of the viscosity in the depletion layers around the spheres and the entropic force due to the overlapping of depletion zones have a significant influence on the correlated Brownian interactions.
Comparison between transient and frequency modulated excitation: Application to silicon nitride and aluminum oxide coatings of silicon
Authors: Klein D. , Ohm W. , Fengler S. , Kunst M.
Published: June 2014

Contactless measurements of the lifetime of charge carriers are presented with varying ways of photo excitation: with and without bias light and pulsed and frequency modulated. These methods are applied to the study of the surface passivation of single crystalline silicon by a-SiNx:H and Al2O3 coatings. The properties of these coatings are investigated under consideration of the merits of the different methods.
The length and time scales of water's glass transitions
Authors: Limmer David T.
Published: June 2014

Using a general model for the equilibrium dynamics of supercooled liquids, I compute from molecular properties the emergent length and time scales that govern the nonequilibrium relaxation behavior of amorphous ice prepared by rapid cooling. Upon cooling, the liquid water falls out of equilibrium whereby the temperature dependence of its relaxation time is predicted to change from super-Arrhenius to Arrhenius. A consequence of this crossover is that the location of the apparent glass transition temperature depends logarithmically on cooling rate. Accompanying vitrification is the emergence of a dynamical length-scale, the size of which depends on the cooling rate and varies between angstroms and tens of nanometers. While this protocol dependence clarifies a number of previous experimental observations for amorphous ice, the arguments are general and can be extended to other glass forming liquids.
Liquid-vapor transition and critical behavior of the ultrasoft restricted primitive model of polyelectrolytes: A Monte Carlo study
Authors: Caillol J.-M. , Levesque D.
Published: June 2014

We present a Monte Carlo study of the liquid-vapor transition and the critical behavior of a model of polyelectrolytes with soft Gaussian charge distributions introduced recently by Coslovich, Hansen, and Kahl [J. Chem. Phys. 134, 244514 (2011)]. A finite size study involving four different volumes in the grand canonical ensemble yields a precise determination of the critical temperature, chemical potential, and density of the model. Attempts to determine the nature of the criticality and to obtain reliable values for the critical exponents are not conclusive.
Molecular dynamics saddle search adaptive kinetic Monte Carlo
Authors: Chill Samuel T. , Henkelman Graeme
Published: June 2014

A method for accelerating molecular dynamics simulations in rare event systems is described. From each new state visited, high temperature molecular dynamics trajectories are used to discover the set of escape mechanisms and rates. This event table is provided to the adaptive kinetic Monte Carlo algorithm to model the evolution of the system from state to state. Importantly, an estimator for the completeness of the calculated rate table in each state is derived. The method is applied to three model systems: adatom diffusion on Al(100); island diffusion on Pt(111); and vacancy cluster ripening in bulk Fe. Connections to the closely related temperature accelerated dynamics method of Voter and co-workers is discussed.
Formation of liquid crystalline phases in aqueous suspensions of platelet-like tripalmitin nanoparticles
Authors: Schmiele Martin , Gehrer Simone , Westermann Martin , Steiniger Frank , Unruh Tobias
Published: June 2014

Suspensions of platelet-like shaped tripalmitin nanocrystals stabilized by the pure lecithin DLPC and the lecithin blend S100, respectively, have been studied by small-angle x-ray scattering (SAXS) and optical observation of their birefringence at different tripalmitin (PPP) concentrations φPPP. It could be demonstrated that the platelets of these potential drug delivery systems start to form a liquid crystalline phase already at pharmaceutically relevant concentrations φPPP of less than 10 wt. %. The details of this liquid crystalline phase are described here for the first time. As in a previous study [A. Illing et al., Pharm. Res. 21, 592 (2004)] some platelets are found to self-assemble into lamellar stacks above a critical tripalmitin concentration \documentclass[12pt]{minimal}\begin{document}$\varphi _{PPP}^{st}$\end{document}φPPPst of 4  wt. %. In this study another critical concentration \documentclass[12pt]{minimal}\begin{document}$\varphi _{PPP}^{lc}\approx 7$\end{document}φPPPlc≈7 wt. % for DLPC and \documentclass[12pt]{minimal}\begin{document}$\varphi _{PPP}^{lc}\approx 9$\end{document}φPPPlc≈9  wt. % for S100 stabilized dispersions, respectively, has been observed. \documentclass[12pt]{minimal}\begin{document}$\varphi _{PPP}^{lc}$\end{document}φPPPlc describes the transition from a phase of randomly oriented stacked lamellae and remaining non-assembled individual platelets to a phase in which the stacks and non-assembled platelets exhibit an overall preferred orientation. A careful analysis of the experimental data indicates that for concentrations above \documentclass[12pt]{minimal}\begin{document}$\varphi _{PPP}^{lc}$\end{document}φPPPlc the stacked lamellae start to coalesce to rather small liquid crystalline domains of nematically ordered stacks. These liquid crystalline domains can be individually very differently oriented but possess an overall preferred orientation over macroscopic length scales which becomes successively more expressed when further increasing φPPP. The lower critical concentration for the formation of liquid crystalline domains of the DLPC-stabilized suspension compared to \documentclass[12pt]{minimal}\begin{document}$\varphi _{PPP}^{lc}$\end{document}φPPPlc of the S100-stabilized suspension can be explained by a larger aspect ratio of the corresponding tripalmitin platelets. A geometrical model based on the excluded volumes of individual platelets and stacked lamellae has been developed and successfully applied to reproduce the critical volume fractions for both, the onset of stack formation and the appearance of the liquid crystalline phase.
Performance of a beam-multiplexing diamond crystal monochromator at the Linac Coherent Light Source
Authors: Zhu Diling , Feng Yiping , Stoupin Stanislav , Terentyev Sergey A. , Lemke Henrik T. , Fritz David M. , Chollet Matthieu , Glownia J. M. , Alonso-Mori Roberto , Sikorski Marcin , Song Sanghoon , van Driel Tim B. , Williams Garth J. , Messerschmidt Marc , Boutet Sébastien , Blank Vladimir D. , Shvyd'ko Yuri V. , Robert Aymeric
Published: June 2014

A double-crystal diamond monochromator was recently implemented at the Linac Coherent Light Source. It enables splitting pulses generated by the free electron laser in the hard x-ray regime and thus allows the simultaneous operations of two instruments. Both monochromator crystals are High-Pressure High-Temperature grown type-IIa diamond crystal plates with the (111) orientation. The first crystal has a thickness of ∼100 μm to allow high reflectivity within the Bragg bandwidth and good transmission for the other wavelengths for downstream use. The second crystal is about 300 μm thick and makes the exit beam of the monochromator parallel to the incoming beam with an offset of 600 mm. Here we present details on the monochromator design and its performance.
Adiabatic state preparation study of methylene
Authors: Veis Libor , Pittner Jiří
Published: June 2014

Quantum computers attract much attention as they promise to outperform their classical counterparts in solving certain type of problems. One of them with practical applications in quantum chemistry is simulation of complex quantum systems. An essential ingredient of efficient quantum simulation algorithms are initial guesses of the exact wave functions with high enough fidelity. As was proposed in Aspuru-Guzik et al. [Science 309, 1704 (2005)], the exact ground states can in principle be prepared by the adiabatic state preparation method. Here, we apply this approach to preparation of the lowest lying multireference singlet electronic state of methylene and numerically investigate preparation of this state at different molecular geometries. We then propose modifications that lead to speeding up the preparation process. Finally, we decompose the minimal adiabatic state preparation employing the direct mapping in terms of two-qubit interactions.
Multi-phonon-assisted absorption and emission in semiconductors and its potential for laser refrigeration
Authors: Khurgin Jacob B.
Published: June 2014

Laser cooling of semiconductors has been an elusive goal for many years, and while attempts to cool the narrow gap semiconductors such as GaAs are yet to succeed, recently, net cooling has been attained in a wider gap CdS. This raises the question of whether wider gap semiconductors with higher phonon energies and stronger electron-phonon coupling are better suitable for laser cooling. In this work, we develop a straightforward theory of phonon-assisted absorption and photoluminescence of semiconductors that involves more than one phonon and use to examine wide gap materials, such as GaN and CdS and compare them with GaAs. The results indicate that while strong electron-phonon coupling in both GaN and CdS definitely improves the prospects of laser cooling, large phonon energy in GaN may be a limitation, which makes CdS a better prospect for laser cooling.
Seniority zero pair coupled cluster doubles theory
Authors: Stein Tamar , Henderson Thomas M. , Scuseria Gustavo E.
Published: June 2014

Coupled cluster theory with single and double excitations accurately describes weak electron correlation but is known to fail in cases of strong static correlation. Fascinatingly, however, pair coupled cluster doubles (p-CCD), a simplified version of the theory limited to pair excitations that preserve the seniority of the reference determinant (i.e., the number of unpaired electrons), has mean field computational cost and is an excellent approximation to the full configuration interaction (FCI) of the paired space provided that the orbital basis defining the pairing scheme is adequately optimized. In previous work, we have shown that optimization of the pairing scheme in the seniority zero FCI leads to a very accurate description of static correlation. The same conclusion extends to p-CCD if the orbitals are optimized to make the p-CCD energy stationary. We here demonstrate these results with numerous examples. We also explore the contributions of different seniority sectors to the coupled cluster doubles (CCD) correlation energy using different orbital bases. We consider both Hartree-Fock and Brueckner orbitals, and the role of orbital localization. We show how one can pair the orbitals so that the role of the Brueckner orbitals at the CCD level is retained at the p-CCD level. Moreover, we explore ways of extending CCD to accurately describe strongly correlated systems.
Projected seniority-two orbital optimization of the antisymmetric product of one-reference orbital geminal
Authors: Boguslawski Katharina , Tecmer Paweł , Limacher Peter A. , Johnson Paul A. , Ayers Paul W. , Bultinck Patrick , De Baerdemacker Stijn , Van Neck Dimitri
Published: June 2014

We present a new, non-variational orbital-optimization scheme for the antisymmetric product of one-reference orbital geminal wave function. Our approach is motivated by the observation that an orbital-optimized seniority-zero configuration interaction (CI) expansion yields similar results to an orbital-optimized seniority-zero-plus-two CI expansion [L. Bytautas, T. M. Henderson, C. A. Jimenez-Hoyos, J. K. Ellis, and G. E. Scuseria, J. Chem. Phys. 135, 044119 (2011)]. A numerical analysis is performed for the C2 and LiF molecules, for the CH2 singlet diradical as well as for the symmetric stretching of hypothetical (linear) hydrogen chains. For these test cases, the proposed orbital-optimization protocol yields similar results to its variational orbital optimization counterpart, but prevents symmetry-breaking of molecular orbitals in most cases.
Effects of electromagnetic forcing on self-sustained jet oscillations
Authors: Kalter R. , Tummers M. J. , Kenjereš S. , Righolt B. W. , Kleijn C. R.
Published: June 2014

The influence of electromagnetic forcing on self-sustained oscillations of a jet issuing from a submerged nozzle into a thin vertical cavity (width W much larger than thickness T) has been studied using particle image velocimetry. A permanent Lorentz force is produced by applying an electrical current across the width of the cavity in conjunction with a magnetic field from three permanent magnets across its thickness. As a working fluid a saline solution is used. The magnetic field is in the north-south-north configuration, such that the Lorentz force can be applied in an up-down-up configuration or in a down-up-down configuration by switching the direction of the electrical current. A critical Stuart number Nc was found. For N < Nc, the jet oscillates with a constant Strouhal number St, independent of the Reynolds number Re. For N > Nc and an oscillation enhancing up-down-up configuration of the Lorentz force, St grows with N as St \documentclass[12pt]{minimal}\begin{document}$\propto \sqrt{\mathrm{N}}$\end{document}∝N. In contrast, for N > Nc and an oscillation suppressing down-up-down configuration of the Lorentz force, all jet oscillations are suppressed.
Metastable Lennard-Jones fluids. II. Thermal conductivity
Authors: Baidakov Vladimir G. , Protsenko Sergey P.
Published: June 2014

The method of equilibrium molecular dynamics with the use of the Green-Kubo formalism has been used to calculate the thermal conductivity λ in stable and metastable regions of a Lennard-Jones fluid. Calculations have been made in the range of reduced temperatures $0.4 \le T{\kern 1pt} ^* = k_B T/\varepsilon \le 2.0$0.4≤T*=kBT/ɛ≤2.0 and densities $0.01 \le \rho {\kern 1pt} ^* = \rho \sigma ^3 \le 1.2$0.01≤ρ*=ρσ3≤1.2 on 15 isotherms for 234 states, 130 of which refer to metastable regions: superheated and supercooled liquids, supersaturated vapor. Equations have been built up which describe the dependence of the regular part of the thermal conductivity on temperature and density, and also on temperature and pressure. It has been found that in (p, T) variables in the region of a liquid–gas phase transition a family of lines of constant value of excess thermal conductivity Δλ = λ − λ0, where λ0 is the thermal conductivity of a dilute gas, has an envelope which coincides with the spinodal. Thus, at the approach to the spinodal of a superheated liquid and supersaturated vapor (∂Δλ/∂p)T → ∞, (∂Δλ/∂T)p → ∞.
Tuning the local temperature during feedback controlled electromigration in gold nanowires
Authors: Xiang An , Hou Shimin , Liao Jianhui
Published: June 2014

Feedback controlled electromigration (FCE) in metallic nanowires has been widely used for various purposes. However, the control of the local temperature during FCE remains a challenge. Here, we report that the environment temperature can be used as a knob to tune the local temperature during FCE in gold nanowires. FCE was performed in gold nanowires at various environment temperatures ranging from 4.2 K to 300 K. We find that the dissipated power normalized by the cross section area of the nano constriction is linearly proportional to the environment temperature. Interestingly, the estimated local maximum temperature parabolically depends on the environment temperature. A minimum in the local temperature can be reached if an appropriate environment temperature is chosen. Our findings are well supported by the finite element simulation. Moreover, the data indicates the coupling between FCE triggering current density and local temperature.
A Brownian dynamics algorithm for colloids in curved manifolds
Authors: Castro-Villarreal Pavel , Villada-Balbuena Alejandro , Méndez-Alcaraz José Miguel , Castañeda-Priego Ramón , Estrada-Jiménez Sendic
Published: June 2014

The many-particle Langevin equation, written in local coordinates, is used to derive a Brownian dynamics simulation algorithm to study the dynamics of colloids moving on curved manifolds. The predictions of the resulting algorithm for the particular case of free particles diffusing along a circle and on a sphere are tested against analytical results, as well as with simulation data obtained by means of the standard Brownian dynamics algorithm developed by Ermak and McCammon [J. Chem. Phys. 69, 1352 (1978)] using explicitly a confining external field. The latter method allows constraining the particles to move in regions very tightly, emulating the diffusion on the manifold. Additionally, the proposed algorithm is applied to strong correlated systems, namely, paramagnetic colloids along a circle and soft colloids on a sphere, to illustrate its applicability to systems made up of interacting particles.
When do we need to account for the geometric phase in excited state dynamics?
Authors: Ryabinkin Ilya G. , Joubert-Doriol Loïc , Izmaylov Artur F.
Published: June 2014

We investigate the role of the geometric phase (GP) in an internal conversion process when the system changes its electronic state by passing through a conical intersection (CI). Local analysis of a two-dimensional linear vibronic coupling (LVC) model Hamiltonian near the CI shows that the role of the GP is twofold. First, it compensates for a repulsion created by the so-called diagonal Born–Oppenheimer correction. Second, the GP enhances the non-adiabatic transition probability for a wave-packet part that experiences a central collision with the CI. To assess the significance of both GP contributions we propose two indicators that can be computed from parameters of electronic surfaces and initial conditions. To generalize our analysis to N-dimensional systems we introduce a reduction of a general N-dimensional LVC model to an effective 2D LVC model using a mode transformation that preserves short-time dynamics of the original N-dimensional model. Using examples of the bis(methylene) adamantyl and butatriene cations, and the pyrazine molecule we have demonstrated that their effective 2D models reproduce the short-time dynamics of the corresponding full dimensional models, and the introduced indicators are very reliable in assessing GP effects.
Improved parameterization of interatomic potentials for rare gas dimers with density-based energy decomposition analysis
Authors: Zhou Nengjie , Lu Zhenyu , Wu Qin , Zhang Yingkai
Published: June 2014

We examine interatomic interactions for rare gas dimers using the density-based energy decomposition analysis (DEDA) in conjunction with computational results from CCSD(T) at the complete basis set (CBS) limit. The unique DEDA capability of separating frozen density interactions from density relaxation contributions is employed to yield clean interaction components, and the results are found to be consistent with the typical physical picture that density relaxations play a very minimal role in rare gas interactions. Equipped with each interaction component as reference, we develop a new three-term molecular mechanical force field to describe rare gas dimers: a smeared charge multipole model for electrostatics with charge penetration effects, a B3LYP-D3 dispersion term for asymptotically correct long-range attractions that is screened at short-range, and a Born-Mayer exponential function for the repulsion. The resulted force field not only reproduces rare gas interaction energies calculated at the CCSD(T)/CBS level, but also yields each interaction component (electrostatic or van der Waals) which agrees very well with its corresponding reference value.
Configuration change of NO on Cu(110) as a function of temperature
Authors: Shiotari A. , Mitsui T. , Okuyama H. , Hatta S. , Aruga T. , Koitaya T. , Yoshinobu J.
Published: June 2014

The bonding structure of nitric oxide (NO) on Cu(110) is studied by means of scanning tunneling microscopy, reflection absorption infrared spectroscopy, and electron energy loss spectroscopy at 6–160 K. At low temperatures, the NO molecule adsorbs at the short bridge site via the N end in an upright configuration. At around 50 K, this turns into a flat configuration, in which both the N and O atoms interact with the surface. The flat configuration is characterized by the low-frequency N–O stretching mode at 855 cm−1. The flat-lying NO flips back and forth when the temperature increases to ∼80 K, and eventually dissociates at ∼160 K. We propose a potential energy diagram for the conversion of NO on the surface.
Effect of diffusion on Förster resonance energy transfer in low-viscosity solution
Authors: Muratsugu Atsushi , Watanabe Junji , Kinoshita Shuichi
Published: June 2014

The effect of translational diffusion on Förster resonance energy transfer between rhodamine 6G (the donor) and malachite green (the acceptor) was investigated by examining the donor's fluorescence decay profile. Eight straight-chain alkyl alcohols were used, and the temperature of ethanol was changed to vary the viscosity; the decay profiles were analyzed using the theory developed by Gösele. The critical transfer distance obtained from the decay profile is in good agreement with that evaluated using the spectroscopic quantities, and the diffusion coefficients are consistent with the Stokes–Einstein relation. The fluorescence decay profile was described well by Gösele's theory and the effect of diffusion is clearly verified by the temperature/viscosity dependence of the diffusion constant.