bluuebunny/crossref_metadata_2025 huggingface dataset:
Eine Zufallsentdeckung und ihr Erfinder: 75 Jahre Oxo‐Synthese
Authors: Rasch Manfred
Published: November 2013

Seit September ist das Werk Ruhrchemie der Oxea eine “Historische Stätte der Chemie”. Die GDCh würdigt damit die Forschung von Otto Roelen. Die Oxo‐Synthese ist bis heute eine weit verbreitete Reaktion, ihr Erfinder dagegen eher unbekannt.
Verdrehter Tausendsassa
Authors: Petzold Holm , Heider Silvio
Published: November 2013

2,2",6,6"‐substituierte Biphenyle sind funktionale Bausteine für vielfältige Anwendungen wie Protonenschwämme, dynamische Redoxsysteme und Brückenliganden in zweikernigen Metallkomplexen.
Stimmt das Volumen der Pipette?
Authors: Romaguera Antonio
Published: November 2013

Nahezu jedes Labor nutzt Kolbenhubpipetten mit Luftpolster, im allgemeinen Sprachgebrauch oft als Mikroliterpipetten bezeichnet. Diese sind im Rahmen der Prüfmittelüberwachung regelmäßig zu kalibrieren. Da Faktoren wie Luftfeuchtigkeit und Temperatur die Ergebnisse stark beeinflussen, sind die Prüfbedingungen exakt einzuhalten. Worauf kommt es wirklich an?
Qualität und Vergleichbarkeit durch zentrale Abiturprüfungen?
Authors: Kühn Svenja Mareike
Published: November 2013

Die Einführung zentraler Abiturprüfungen war eine gewichtige bildungspolitische Maßnahme im Zuge der Diskurse um Qualität und Vergleichbarkeit der Schulbildung. Wie schriftliche Abituraufgaben in Chemie gestaltet sind und inwiefern Unterschiede zwischen zentraler und dezentraler Aufgabenstellung bestehen, zeigen vier Bundesländer mit unterschiedlichen Prüfungstraditionen.
The Effect of Mandatory Seat Belt Laws on Seat Belt Use by Socioeconomic Position
Authors: Harper Sam , Strumpf Erin C. , Burris Scott , Smith George Davey , Lynch John
Published: November 2013

We investigated the differential effect of mandatory seat belt laws on seat belt use among socioeconomic subgroups. We identified the differential effect of legislation across higher versus lower education individuals using a difference‐in‐differences model based on state variations in the timing of the passage of laws. We find strong effects of mandatory seat belt laws for all education groups, but the effect is stronger for those with fewer years of education. In addition, we find that the differential effect by education is larger for mandatory seat belt laws with primary rather than secondary enforcement. Our results imply that existing socioeconomic differences in seat belt use would be further mitigated if all states upgraded to primary enforcement.
Metamorphic malware detection using base malware identification approach
Authors: Mahawer Devendra Kumar , Nagaraju A.
Published: November 2013

Malware is a malicious program that is intentionally developed to harm computer systems. Because the metamorphic malwares are advanced in nature, they mutate their code in each generation by employing code obfuscation techniques to thwart detection. Conventional scanners even fail to detect all variants of such malware. In the view of metamorphic malware detection, we have proposed the concept of machine learning approach like support vector machine with histogram intersection kernel. It has been successfully implemented in the area of image classification, bioinformatics (protein classification and cancer classification). This method provides more accuracy in terms of detection rate to build the effective detection system for metamorphic malwares. In the proposed method, we first extract feature histograms from each portable executable file and map them into the feature space using a histogram intersection kernel. The histogram intersection kernel helps us to find the optimal hyperplane for separating the metamorphic variants from benign programs in a feature space of very high dimension. The results show that our proposed method is capable of detecting metamorphic variants with few false alarms or misses. Copyright © 2013 John Wiley & Sons, Ltd.
Thermodynamic and Kinetic Model of the Converter Steelmaking Process. Part 1: The Description of the BOF Model
Authors: Lytvynyuk Yuriy , Schenk Johannes , Hiebler Martin , Sormann Axel
Published: November 2013

A new model for the simulation of the converter steelmaking process was developed after the detailed study of existing thermodynamic and kinetic models and approaches. This model consists of the reaction model and models for charge materials melting and dissolution. The reaction model is based on the coupled reaction model, which includes the combination of both thermodynamics and kinetics of the involved phases. The models of charge material melting and dissolution include the definition of the driving force for the melting and dissolution, and the mass transfer coefficients in the metal and slag phases.
Investigation of bond behaviour between recycled aggregate concrete and deformed steel bars
Authors: Prince M. John Robert , Singh Bhupinder
Published: November 2013

The results of 45 pullout tests on 8, 10 and 12 mm diameter deformed steel bars concentrically embedded in recycled aggregate concrete designed using equivalent mix proportions with coarse recycled concrete aggregate (RCA) replacement levels of 25, 50, 75 and 100 % are described here. Although consistent results were not obtained for the 8 mm bars, the normalized bond strengths of the 10 and 12 mm bars across all RCA replacement levels were higher for the RCA concretes compared with the natural coarse aggregate concrete, and they increased with RCA replacement levels. Brittleness index, an analogous parameter from rock mechanics, has been shown to be a relevant predictor of the measured bond strengths. An empirical bond stress–slip relationship has been proposed and it has been conservatively suggested that anchorage lengths for the 10 and 12 mm deformed bars in recycled aggregate concrete may be taken to be the same as those in natural aggregate concrete.
Two 2D 3d‐4f Heterometallic Coordination Polymers with [Ln2(IN)6(OH)]– Clusters and [Cu4Br3]nn+ Chains
Authors: Fan Le‐Qing , Wu Ji‐Huai , Huang Yun‐Fang
Published: November 2013

Two 2D 3d‐4f heterometallic coordination polymers, [Ln2Cu4Br3(IN)6(OH)(H2O)4]n [Ln = Ho (1) and Yb (2), HIN = isonicotinic acid], were synthesized by hydrothermal reaction of Ln2O3, CuBr2, and HIN with HNO3, and characterized by elemental analyses, IR spectroscopy, PXRD, and single‐crystal X‐ray diffraction. Structural analyses revealed that 1 and 2 are isostructural and have a 2D structure, which consists [Cu4Br3]nn+ chains linked by dinuclear [Ln2(IN)6(OH)]– clusters. Additionally, the thermogravimetric analysis and luminescent properties of 1 were investigated and discussed.
Concomitant Endoscopic Carpal and Cubital Tunnel Release: Safety and Efficacy
Authors: Cross Danielle , Matullo Kristofer S.
Published: November 2013

Background

When performed alone, endoscopic carpal tunnel release and endoscopic cubital tunnel release are safe and effective surgical options for the treatment of carpal and cubital tunnel syndromes, respectively. However, there is currently no literature that describes the performance of both procedures concomitantly. We describe the results of 17 cases in which dual endoscopic carpal and cubital tunnel releases were performed for the treatment of concurrent carpal and cubital tunnel syndromes.

Methods

A retrospective review of all patients in a single surgeon practice that presented with concomitant ipsilateral carpal and cubital tunnel syndromes was performed. Within an 8-month period, 17 patients had undergone 19 concomitant ipsilateral endoscopic carpal and cubital tunnel releases after failing conservative treatment. Pre- and postoperative measurements included subjective numbness/tingling; subjective pain; manual muscle testing of the abductor pollicis brevis (APB), intrinsics, and flexor digitorum profundus (FDP); static two-point discrimination; quick-DASH (Disabilities of the Arm, Shoulder and Hand) scores; grip strength; chuck pinch strength; and key pinch strength. Complete data are available for 15 patients and 17 total procedures.

Results

Thirteen male and four female patients (average age of 50.5) underwent dual endoscopic cubital and carpal tunnel release. Two patients were lost to follow-up and eliminated from data analysis. Pre- and postoperative comparisons were completed for median DASH scores, grip strength, chuck pinch strength, and key pinch strength at their preoperative visit and at 12 weeks. DASH scores improved significantly from a median of 67.5 to 16 ( p =0.002), grip strengths improved from 42 to 55.0 lbs ( p =0.30), chuck pinch strengths improved significantly from 11 to 15.5 lbs ( p =0.02), and key pinch strengths increased significantly from 13 to 18 lbs ( p = 0.003). Average static two-point discrimination decreased from 5.9 to 4.8 mm. In terms of pain, 82 % of patients had complete resolution of pain, and the remaining 18 % experienced pain only with strenuous activity. In terms of numbness/tingling, 100 % of patients had complete resolution of median nerve symptoms; 88 % of patients had substantial improvement of numbness and tingling symptoms, and 12 % had residual ulnar nerve symptoms. In terms of muscle strength, 92 % of patients had improvement to 5/5 APB strength, while 100 % of patients had improvement to 5/5 intrinsic and FDP strengths. Two minor complications occurred, including one superficial hematoma and one superficial cellulitis.

Conclusions

Preliminary data demonstrate that dual endoscopic carpal and cubital tunnel release is a safe and effective treatment option for patients who present with concurrent cubital and carpal tunnel syndromes recalcitrant to non-surgical management. Postoperative results and complications are comparable to endoscopic carpal and cubital tunnel releases performed alone.
Anatomical and physiological changes in pelvic diaphragm in patients with chagasic megacolon submitted to Duhamel surgery
Authors: Júnior Hélio Moreira , Moreira José P.T. , Isaac Raniere R. , de Almeida Arminda C. , Moreira Hélio , Klug Wilmar A.
Published: November 2013

Original contribution understand the reasons why Duhamel surgery results in clinical improvement of constipation in patients with Chagasic colopathy.

Background Duhamel surgery is one of the most widespread techniques for the treatment of Chagasic megacolon, with low rates of recurrence of constipation.

Objective evaluate the anatomical and physiological changes in the pelvic diaphragm of patients with chagasic colopathy, as well as changes occurring after undergoing Duhamel surgery.

Design clinical data and results of cinedefecography, electromanometry and anorectal ultrasound of the anal canal were evaluated in patients with Chagasic colopathy, before and after Duhamel surgery.

Location Service of Coloproctology – Departament of Surgery, Faculdade de Medicina da Universidade Federal de Goiás. Patients: patients with positive serology for Chagas Disease, with constipation and radiological megacolon, who presented consecutively to the Chagas outpatient clinic and freely agreed to participate in this study, were prospectively included.

Results a total of 20 patients were included, with a mean age of 53.2 years, of which 16 were women. The following parameters were observed in the postoperative period: change in bowel frequency, of, on average, one evacuation every ten days to daily bowel movement; 16 patients used laxatives preoperatively and only one did, intermittently, in postoperative period. Electromanometry showed, postoperatively, a decrease in anal resting pressure (60.88 to 37.2 mmHg p < 0.001) and anal squeeze pressures (244.3 mL to 161.25 p = 0.01), whereas ultrasound showed that 75% of the patients had abnormalities of the internal anal sphincter in the posterior anal canal juxtaposed to the pulled-through colon. Postoperative rectal emptying observed in cinedefecographic tests occurred more quickly and with less effort when compared with the preoperative findings. There was a change in the anorectal angle postoperatively, which became more obtuse, both during rest, straining and during evacuation.

Conclusions the anatomical and functional changes in the pelvic diaphragm are significant after Duhamel surgery and together, they result in clinical improvement of patients.
Risks and benefits of colonoscopy in patients aged 80 and older: A prospective study
Authors: da Silva Edson Jurado
Published: November 2013

Objective this study aims to compare colonoscopy results in patients aged 50-79 and those aged 80 and older.

Patients and Methods a total of 533 diagnostic colonoscopies performed from August 2011 to January 2012 were evaluated in a prospective study analyzing age, ASA classification, comorbidities, endoscopic findings, time to reach the cecum, number of complete examinations, difficulties and complications. Chi-square test was used to compare categorical data whereas Student's t test to compare means. A p value < 0.05 was considered significant.

Results 479 patients were in Group A — age 50 to 79, whereas 54 were in Group B, 80 versus older. The following results are shown for Group A and B, respectively: age 63 ± 8 versus 84 ± 4 years. ASA 1 difficult examination: 58 (21%) versus 12 (27%) p > 0.05, ASA > 2 difficult examination: 41 (20%) versus 6 (60%) p < 0,05. Comorbidities 255 (53%) versus 36 (66%) p > 0.05. Complete colonoscopy in 450 (94%) versus 45 (83%), p < 0.01. Difficulties in 99 (20%) versus 32 (40%), p < 0.01. Complications in 1 (0.2%) versus 3 (5%) p < 0.01. Diverticulitis/sequelae in 3 (0.6%) versus 3 (5%) p < 0.01. CRC in 42 (8.7%) and 10 (18.5%), p < 0.05. Adenoma in 130 (27%) versus 15 (27%), p > 0.05 Time to reach the cecum was 39 ± 10 minutes for difficult procedures and 13 ± 9 for the easy ones.

Conclusion age 80 and older is associated with more adverse events during colonoscopy.
Carbon dioxide dissolution in structural and stratigraphic traps
Authors: Szulczewski M. L. , Hesse M. A. , Juanes R.
Published: November 2013

The geologic sequestration of carbon dioxide ( CO2) in structural and stratigraphic traps is a viable option to reduce anthropogenic emissions. While dissolution of the CO2 stored in these traps reduces the long-term leakage risk, the dissolution process remains poorly understood in systems that reflect the appropriate subsurface geometry. Here, we study dissolution in a porous layer that exhibits a feature relevant for CO2 storage in structural and stratigraphic traps: a finite CO2 source along the top boundary that extends only part way into the layer. This feature represents the finite extent of the interface between free-phase CO2 pooled in a trap and the underlying brine. Using theory and simulations, we describe the dissolution mechanisms in this system for a wide range of times and Rayleigh numbers, and classify the behaviour into seven regimes. For each regime, we quantify the dissolution flux numerically and model it analytically, with the goal of providing simple expressions to estimate the dissolution rate in real systems. We find that, at late times, the dissolution flux decreases relative to early times as the flow of unsaturated water to the CO2 source becomes constrained by a lateral exchange flow though the reservoir. Application of the models to several representative reservoirs indicates that dissolution is strongly affected by the reservoir properties; however, we find that reservoirs with high permeabilities ($k\geq 1$ Darcy) that are tens of metres thick and several kilometres wide could potentially dissolve hundreds of megatons of CO2 in tens of years.
Railroads and American Economic Growth
Authors: Nerlove Marc
Published: November 2013

In his classic paper on the significance of railroads to American economic development, Leland Jenks distinguished three principal avenues of influence: (1) The railroad was what Jenks called an “innovating idea” with important psychological impact “manifested in a wave-like profusion of new enterprise of many sorts.” (2) The railroad and railway construction and maintenance were a stimulus to the industrial and financial sectors of the economy. The railroad not only stimulated the iron and steel, timber, and other industries directly but “encouraged innovations in financial enterprise.” (3) Finally, the railroad contributed directly to the generation of national income through the rendering of transportation services. Although on this last point Jenks despaired that, “There appears to be no satisfactory technique for giving a precise measure to the extent of this contribution.”
Cousinia: morphology, taxonomy, distribution and phytogeographical implications
Authors: Rechinger K. H.
Published: November 2013

Synopsis

Cousinia (Compositae) with over 400 species in SW Asia has its maximum concentration in the Flora Iranica area. Overall it has a remarkably limited distributional range compared with other genera of similar size. On the basis of the significant distribution patterns of Cousinia, it is argued that the highland part of the Flora Iranica area should phytogeographically be re-designated as the Irano-Turkestanian region, including the Central Asian mountain province of Soviet Central Asia. It is also proposed that the essentially lowland Turanian (Aralo-Caspian) area should be excluded from the Irano-Turanian region.
Responsible risk-taking in conflict-affected countries: the need for due diligence and the importance of collective approaches
Authors: Bray John , Crockett Antony
Published: November 2013

This article discusses some of the challenges that may be encountered by companies seeking to adhere to the Voluntary Principles on Security and Human Rights and the United Nations Guiding Principles on Business and Human Rights when operating in conflict-affected countries. The authors argue that corporate respect for human rights may not be sufficient to correct or compensate for state failure and also suggest that the leverage or influence enjoyed by individual companies in relation to the conduct of security forces and host governments may be limited, particularly in times of crisis. There is therefore a need for a collective approach to human rights risks in conflict-affected countries, and this should focus on public security sector reform and good governance as well as on corporate due diligence.
A Novel Neuroprotective Strategy for Ischemic Stroke: Transient Mild Acidosis Treatment by CO2 Inhalation at Reperfusion
Authors: Fan Yan-Ying , Shen Zhe , He Ping , Jiang Lei , Hou Wei-wei , Shen Yao , Zhang Xiang-Nan , Hu Wei-Wei , Chen Zhong
Published: November 2013

Acidosis is one of the key components in cerebral ischemic postconditioning that has emerged recently as an endogenous strategy for neuroprotection. We set out to test whether acidosis treatment at reperfusion can protect against cerebral ischemia/reperfusion injury. Adult male C57BL/6 J mice were subjected to 60-minute middle cerebral arterial occlusion followed by 24-hour reperfusion. Acidosis treatment by inhaling 10%, 20%, or 30% CO2 for 5 or 10 minutes at 5, 50, or 100 minutes after reperfusion was applied. Our results showed that inhaling 20% CO2 for 5 minutes at 5 minutes after reperfusion-induced optimal neuroprotection, as revealed by reduced infarct volume. Attenuating brain acidosis with NaHCO3 significantly compromised the acidosis or ischemic postconditioning-induced neuroprotection. Consistently, both acidosis-treated primary cultured cortical neurons and acute corticostriatal slices were more resistant to oxygen–glucose deprivation/reperfusion insult. In addition, acidosis inhibited ischemia/reperfusion-induced apoptosis, caspase-3 expression, cytochrome c release to cytoplasm, and mitochondrial permeability transition pore (mPTP) opening. The neuroprotection of acidosis was inhibited by the mPTP opener atractyloside both in vivo and in vitro. Taken together, these findings indicate that transient mild acidosis treatment at reperfusion protects against cerebral ischemia/reperfusion injury. This neuroprotection is likely achieved, at least partly, by inhibiting mPTP opening and mitochondria-dependent apoptosis.
Compton scattering for spectroscopic detection of ultra-fast, high flux, broad energy range X-rays
Authors: Cipiccia S. , Wiggins S. M. , Maneuski D. , Brunetti E. , Vieux G. , Yang X. , Issac R. C. , Welsh G. H. , Anania M. , Islam M. R. , Ersfeld B. , Montgomery R. , Smith G. , Hoek M. , Hamilton D. J. , Lemos N. R. C. , Symes D. R. , Rajeev P. P. , Shea V. O. , Dias J. M. , Jaroszynski D. A.
Published: November 2013

Compton side-scattering has been used to simultaneously downshift the energy of keV to MeV energy range photons while attenuating their flux to enable single-shot, spectrally resolved, measurements of high flux X-ray sources to be undertaken. To demonstrate the technique a 1 mm thick pixelated cadmium telluride detector has been used to measure spectra of Compton side-scattered radiation from a Cobalt-60 laboratory source and a high flux, high peak brilliance X-ray source of betatron radiation from a laser-plasma wakefield accelerator.
An optics-based variable-temperature assay system for characterizing thermodynamics of biomolecular reactions on solid support
Authors: Fei Yiyan , Landry James P. , Li Yanhong , Yu Hai , Lau Kam , Huang Shengshu , Chokhawala Harshal A. , Chen Xi , Zhu X. D.
Published: November 2013

A biological state is equilibrium of multiple concurrent biomolecular reactions. The relative importance of these reactions depends on physiological temperature typically between 10 °C and 50 °C. Experimentally the temperature dependence of binding reaction constants reveals thermodynamics and thus details of these biomolecular processes. We developed a variable-temperature opto-fluidic system for real-time measurement of multiple (400–10 000) biomolecular binding reactions on solid supports from 10 °C to 60 °C within ±0.1 °C. We illustrate the performance of this system with investigation of binding reactions of plant lectins (carbohydrate-binding proteins) with 24 synthetic glycans (i.e., carbohydrates). We found that the lectin-glycan reactions in general can be enthalpy-driven, entropy-driven, or both, and water molecules play critical roles in the thermodynamics of these reactions.
On a Riesz basis of exponentials related to the eigenvalues of an analytic operator and application to a non-selfadjoint problem deduced from a perturbation method for sound radiation
Authors: Ellouz Hanen , Feki Ines , Jeribi Aref
Published: November 2013

In the present paper, we prove that the family of exponentials associated to the eigenvalues of the perturbed operator T(ɛ) ≔ T0 + ɛT1 + ɛ2T2 + … + ɛkTk + … forms a Riesz basis in L2(0, T), T > 0, where \documentclass[12pt]{minimal}\begin{document}$\varepsilon \in \mathbb {C}$\end{document}ɛ∈C, T0 is a closed densely defined linear operator on a separable Hilbert space \documentclass[12pt]{minimal}\begin{document}${\cal H}$\end{document}H with domain \documentclass[12pt]{minimal}\begin{document}${\cal D}(T_0)$\end{document}D(T0) having isolated eigenvalues with multiplicity one, while T1, T2, … are linear operators on \documentclass[12pt]{minimal}\begin{document}${\cal H}$\end{document}H having the same domain \documentclass[12pt]{minimal}\begin{document}${\cal D}\supset {\cal D}(T_0)$\end{document}D⊃D(T0) and satisfying a specific growing inequality. After that, we generalize this result using a H-Lipschitz function. As application, we consider a non-selfadjoint problem deduced from a perturbation method for sound radiation.
Binary nucleation rates for ethanol/water mixtures in supersonic Laval nozzles: Analyses by the first and second nucleation theorems
Authors: Tanimura Shinobu , Pathak Harshad , Wyslouzil Barbara E.
Published: November 2013

We performed pressure trace measurements and small angle x-ray scattering measurements to determine the vapor-liquid nucleation rates of EtOH/H2O mixtures including pure EtOH and pure H2O in two supersonic Laval nozzles with different expansion rates. The nucleation rates varied from 0.9 × 1017 to 16 × 1017 cm−3 s−1 over the temperature range of 210 K to 230 K, EtOH activity range of 0 to 11.6, and H2O activity range of 0 to 124. The first and second nucleation theorems were applied to the nucleation rates to estimate the sizes, compositions, and excess energies of the critical clusters. The critical clusters contained from 4 to 15 molecules for pure H2O and EtOH/H2O clusters, and from 16 to 23 molecules for pure EtOH clusters. Comparing the excess energies of the pure H2O critical clusters with the results of a quantum-chemistry calculation suggested that the pre-factor of the theoretical nucleation rate is almost constant regardless of the monomer concentration. One possible explanation for this result is that cooling of the critical clusters limits the nucleation rate under the highly supersaturated conditions. The results of the analyses also yielded the relation between the surface energy and the composition of the critical clusters, where the latter are predicted to consist only of surface molecules. Applying this relationship to the EtOH/H2O bulk liquid mixtures, we estimated the EtOH mole fraction in the surface layer and found it is higher than that derived from the surface tension based on the Gibbs adsorption equation when the EtOH mole fraction in the liquid is higher than about 0.2 mol/mol. This discrepancy was attributed to the existence of the EtOH depletion layer just below the surface layer of the liquid.
Spectroscopy and applications of the 3 3Σ+ electronic state of 39K85Rb
Authors: Banerjee Jayita , Rahmlow David , Carollo Ryan , Bellos Michael , Eyler Edward E. , Gould Phillip L. , Stwalley William C.
Published: November 2013

We report new results on the spectroscopy of the 3 3Σ+ electronic state of 39K85Rb. The observations are based on resonance-enhanced multiphoton ionization of ultracold KRb molecules starting in vibrational levels v′′ = 18–23 of the a 3Σ+ state and ionized via the intermediate 3 3Σ+ state. The a-state ultracold molecules are formed by photoassociation of ultracold 39K and 85Rb atoms to the 3(0+) state of KRb followed by spontaneous emission. We discuss the potential applications of this state to future experiments, as a pathway for populating the lowest vibrational levels of the a state as well as the X state.
Tin-phosphate glass anode for sodium ion batteries
Authors: Honma Tsuyoshi , Togashi Takuya , Kondo Hiroatsu , Komatsu Takayuki , Yamauchi Hideo , Sakamoto Akihiko , Sakai Tetsuo
Published: November 2013

The electrochemical property of tin-phosphate (designate as GSPO) glass anode for the sodium ion battery was studied. During the first charge process, sodium ion diffused into GSPO glass matrix and due to the reduction of Sn2+ to Sn0 state sodiated tin metal nano-size particles are formed in oxide glass matrix. After the second cycle, we confirmed the steady reversible reaction ∼320 mAh/g at 0–1 V cutoff voltage condition by alloying process in NaxSn4. The tin-phosphate glass is a promising candidate of new anode active material that realizes high energy density sodium ion batteries.
Communication: Random phase approximation renormalized many-body perturbation theory
Authors: Bates Jefferson E. , Furche Filipp
Published: November 2013

We derive a renormalized many-body perturbation theory (MBPT) starting from the random phase approximation (RPA). This RPA-renormalized perturbation theory extends the scope of single-reference MBPT methods to small-gap systems without significantly increasing the computational cost. The leading correction to RPA, termed the approximate exchange kernel (AXK), substantially improves upon RPA atomization energies and ionization potentials without affecting other properties such as barrier heights where RPA is already accurate. Thus, AXK is more balanced than second-order screened exchange [A. Grüneis et al., J. Chem. Phys. 131, 154115 (2009)], which tends to overcorrect RPA for systems with stronger static correlation. Similarly, AXK avoids the divergence of second-order Møller-Plesset (MP2) theory for small gap systems and delivers a much more consistent performance than MP2 across the periodic table at comparable cost. RPA+AXK thus is an accurate, non-empirical, and robust tool to assess and improve semi-local density functional theory for a wide range of systems previously inaccessible to first-principles electronic structure calculations.
Dynamics of polymer adsorption from dilute solution in shear flow near a planar wall
Authors: Dutta Sarit , Dorfman Kevin D. , Kumar Satish
Published: November 2013

Adsorption of polymers from dilute solution subject to shear flow near a planar wall is studied using kinetic theory. A dumbbell model consisting of two beads connected by a nonlinear spring is used to describe the polymer molecules, and the beads interact with the wall via a short-range exponential potential. Bead-bead and bead-wall hydrodynamic interactions are also included in the theory. For an initially bare surface, it is found that the quantity of polymer adsorbed decreases with an increase in polymer molecular weight at a given shear rate and point in time. In addition, for a given molecular weight and point in time, the quantity adsorbed decreases with an increase in shear rate. When adsorbed polymer is initially present, similar trends are observed. Furthermore, complete desorption can be achieved at a sufficiently high shear rate. In all cases, the time required to approach a steady value of the adsorbed amount is many orders of magnitude larger than the dumbbell relaxation time. The above findings are in qualitative agreement with experimental measurements reported nearly three decades ago by Lee and Fuller [J. Colloid Interface Sci. 103, 569 (1985)]. Our findings also suggest that the physical mechanism underlying the long-standing observation that shear flow inhibits polymer adsorption and assists polymer desorption is hydrodynamic interaction between stretched polymer molecules and the adsorbing surface.
A computational investigation of attrition-enhanced chiral symmetry breaking in conglomerate crystals
Authors: Ricci Francesco , Stillinger Frank H. , Debenedetti Pablo G.
Published: November 2013

Attrition-enhanced chiral symmetry breaking in crystals, also known as Viedma ripening, is a remarkable phenomenon from a variety of perspectives. By providing a direct route to solid-phase homochirality in a controllable manner, it is of inherent interest to those who study chiral symmetry-breaking/amplification mechanisms. When applied to intrinsically chiral molecules, Viedma ripening may have implications for the origin of biological homochirality, as well as applications in chiral drug resolution. Despite an abundance of research, the mechanistic details underlying this phenomenon have not been unambiguously elucidated. We employ a Monte Carlo algorithm to study this driven system, in order to gain further insights into the mechanisms capable of reproducing key experimental signatures. We provide a comprehensive numerical investigation of how the model parameters (attrition rate, liquid-phase racemization kinetics, and the relative rates of growth and dissolution kinetics) impact the system's overall behavior. It is shown that size-dependent crystal solubility alone is insufficient to reproduce most of the experimental signatures of Viedma ripening, and that some form of a solid-phase chiral feedback mechanism must be invoked in order to reproduce experimentally observed behavior. In this work, such feedback mechanisms can take the form of agglomeration, or of artificial modification of the size dependent growth kinetics.
First-principles prediction of magnetic superatoms in 4d-transition-metal-doped magnesium clusters
Authors: Ge Gui-Xian , Han Yan , Wan Jian-Guo , Zhao Ji-Jun , Wang Guang-Hou
Published: November 2013

We theoretically predict magnetic superatoms in the 4d-transition-metal-doped Mg8 clusters using a spin-polarized density functional theory method. We demonstrate that TcMg8 is highly energetically stable in both structure and magnetic states, and identify it as a magnetic superatom with a magnetic moment as large as 5 μB. The magnetic TcMg8 with 23 valence electrons has a configuration of 1S21P61D10 closed shell and 2S12D4 open shell, complying with Hund's rule similar to the single atom. We elucidate the formation mechanism of the magnetic TcMg8 superatom based on the detailed analysis of molecular orbitals, and attribute it to the large exchange interaction and moderate crystal field effect. Finally, we predict that the magnetic TcMg8 may exhibit semiconductor-like property with spin polarization characteristics.
A first principle study for the adsorption and absorption of carbon atom and the CO dissociation on Ir(100) surface
Authors: Erikat I. A. , Hamad B. A.
Published: November 2013

We employ density functional theory to examine the adsorption and absorption of carbon atom as well as the dissociation of carbon monoxide on Ir(100) surface. We find that carbon atoms bind strongly with Ir(100) surface and prefer the high coordination hollow site for all coverages. In the case of 0.75 ML coverage of carbon, we obtain a bridging metal structure due to the balance between Ir–C and Ir–Ir interactions. In the subsurface region, the carbon atom prefers the octahedral site of Ir(100) surface. We find large diffusion barrier for carbon atom into Ir(100) surface (2.70 eV) due to the strong bonding between carbon atom and Ir(100) surface, whereas we find a very small segregation barrier (0.22 eV) from subsurface to the surface. The minimum energy path and energy barrier for the dissociation of CO on Ir(100) surface are obtained by using climbing image nudge elastic band. The energy barrier of CO dissociation on Ir(100) surface is found to be 3.01 eV, which is appreciably larger than the association energy (1.61 eV) of this molecule.
Theoretical study of amino derivatives and anticancer platinum drug grafted on various carbon nanostructures
Authors: Kraszewski S. , Duverger E. , Ramseyer C. , Picaud F.
Published: November 2013

Density functional theory calculations with van der Waals approximation have been conducted to analyze the functionalization of various carbon-based nanostructures (fullerene, metallic, and semi-conducting nanotubes) with amino derivative groups. The results obtained with azomethine, show the formation of a five membered ring on fullerenes, and on nanotubes consistent with experimental observations. The attachment of an azomethine plus subsequent drug like a Pt(IV) complex does not perturb the cycloaddition process. Moreover, all theoretical results show that the length of different amino derivatives with subsequent Pt(IV) complex does not affect the complexed therapeutic agent when it is attached onto these carbon-based nanostructures.
Ab initio structural and spectroscopic study of HPSx and HSPx (x = 0,+1,−1) in the gas phase
Authors: Yaghlane Saida Ben , Cotton C. Eric , Francisco Joseph S. , Linguerri Roberto , Hochlaf Majdi
Published: November 2013

Accurate ab initio computations of structural and spectroscopic parameters for the HPS/HSP molecules and corresponding cations and anions have been performed. For the electronic structure computations, standard and explicitly correlated coupled cluster techniques in conjunction with large basis sets have been adopted. In particular, we present equilibrium geometries, rotational constants, harmonic vibrational frequencies, adiabatic ionization energies, electron affinities, and, for the neutral species, singlet-triplet relative energies. Besides, the full-dimensional potential energy surfaces (PESs) for HPSx and HSPx (x = −1,0,1) systems have been generated at the standard coupled cluster level with a basis set of augmented quintuple-zeta quality. By applying perturbation theory to the calculated PESs, an extended set of spectroscopic constants, including τ, first-order centrifugal distortion and anharmonic vibrational constants has been obtained. In addition, the potentials have been used in a variational approach to deduce the whole pattern of vibrational levels up to 4000 cm−1 above the minima of the corresponding PESs.
Electronic structure of magnetic semiconductor CdCr2Te4: A possible spin-dependent symmetry filter
Authors: Sims H. , Ramasamy K. , Butler W. H. , Gupta A.
Published: November 2013

We present a theoretical investigation of the electronic and magnetic structure of spinel CdCr2Te4 using density functional theory, its extensions via onsite Hubbard U interactions, and a screened-hybrid-functional exchange potential. We find that the ground state is semiconducting within the latter approach, and within this magnetic-semiconducting system, we compute the complex band structure, finding a slowly decaying evanescent Δ̃1 state possibly suitable for realizing a spin-dependent symmetry filter effect.
Compact low resolution spectrograph, an imaging and long slit spectrograph for robotic telescopes
Authors: Rabaza O. , Jelinek M. , Castro-Tirado A. J. , Cunniffe R. , Zeman J. , Hudec R. , Sabau-Graziati L. , Ruedas-Sánchez J.
Published: November 2013

The COmpact LOw REsolution Spectrograph (COLORES) is a compact and lightweight (13 kg) f/8 imaging spectrograph designed for robotic telescopes, now installed and operating on the TELMA, a rapid-slewing 60 cm telescope of the BOOTES-2 observatory in Málaga (Spain). COLORES is a multi-mode instrument that enables the observer to seamlessly switch between low-dispersion spectroscopy and direct imaging modes during an observation. In this paper, we describe the instrument and its development, from the initial scientific requirements through the optical design process to final configuration with theoretical performance calculations. The mechanical and electronic design is described, methods of calibration are discussed and early laboratory and scientific results are shown.
A Method for testing the integrated thermal resistance of thermoelectric modules
Authors: Gao Junling , Du Qungui , Chen Min
Published: November 2013

The integrated thermal resistance (ITR) of thermoelectric modules (TEMs) is an important parameter that represents the thermal-conduction of ceramic substrates, copper conducting strips, and welding material used in the TEM as well as the thermal contact resistances between different materials. In this study, an accurate and practical test method is proposed for the ITR of TEMs according to thermoelectric heat transfer theory and the equivalent characteristics of heat flux through the cold and hot sides of TEMs in an open-circuit situation. By using such measurements and comparisons, it is verified that the measured ITR value in our mode is accurate and reliable. In particular this method accurately predicts the actual operating conditions of TEMs, in which TEMs are under certain mechanical pressure. It effectively solves the problem of thermal resistance extraction from operating TEMs and is of great significance in their analysis and optimization.
A simple constrained uniaxial tensile apparatus for in situ investigation of film stretching processing
Authors: Meng Lingpu , Li Jing , Cui Kunpeng , Chen Xiaowei , Lin Yuanfei , Xu Jiali , Li Liangbin
Published: November 2013

A simple constrained uniaxial tensile apparatus was designed and constructed to obtain stress-strain curve during stretching and subsequent structural evolution of polymeric films. Stretch is carried out through two motor driven clamps in the machine direction and scissor-like clamps in the transverse direction keeping the sample width constant. The force information during film stretching process is recorded by a tension sensor and structural evolution can be obtained by in situ X-ray scattering technique. All parameters related to film stretching manufacturing, such as temperature, draw ratio, and stretching speed can be set independently, making the apparatus an effective method to explore the relationship between processing parameters and structure.
Sagdeev potential approach for large amplitude compressional Alfvenic double layers in viscous plasmas
Authors: Panwar Anuraj , Rizvi H. , Ryu C. M.
Published: November 2013

Sagdeev’s technique is used to study the large amplitude compressional Alfvenic double layers in a magnetohydrodynamic plasma taking into account the small plasma β and small values of kinematic viscosity. Dispersive effect raised by non-ideal electron inertia currents perpendicular to the ambient magnetic field. The range of allowed values of the soliton speed, M (Mach number), plasma β (ratio of the plasma thermal pressure to the pressure in the confining magnetic field), and viscosity coefficient, wherein double layer may exist, are determined. In the absence of collisions, viscous dissipation modifies the Sagdeev potential and results in large amplitude compressional Alfvenic double layers. The depth of Sagdeev potential increases with the increasing Mach number and plasma β, however, decreases with the increasing viscosity. The double layer structure increases with the increasing plasma β, but decreases with increasing viscous dissipation μ̃.
Sinc-based method for an efficient solution in the direct space of quantum wave equations with periodic boundary conditions
Authors: Marconcini Paolo , Logoteta Demetrio , Macucci Massimo
Published: November 2013

The solution of differential problems, and in particular of quantum wave equations, can in general be performed both in the direct and in the reciprocal space. However, to achieve the same accuracy, direct-space finite-difference approaches usually involve handling larger algebraic problems with respect to the approaches based on the Fourier transform in reciprocal space. This is the result of the errors that direct-space discretization formulas introduce into the treatment of derivatives. Here, we propose an approach, relying on a set of sinc-based functions, that allows us to achieve an exact representation of the derivatives in the direct space and that is equivalent to the solution in the reciprocal space. We apply this method to the numerical solution of the Dirac equation in an armchair graphene nanoribbon with a potential varying only in the transverse direction.
Growth, steady-state, and time-resolved photoluminescence study of CdTe/MgCdTe double heterostructures on InSb substrates using molecular beam epitaxy
Authors: DiNezza Michael J. , Zhao Xin-Hao , Liu Shi , Kirk Alexander P. , Zhang Yong-Hang
Published: November 2013

CdTe/MgCdTe double heterostructures (DHs) are grown on InSb substrates using molecular beam epitaxy and reveal strong photoluminescence with over double the intensity of a GaAs/AlGaAs DH with an identical layer structure design grown on GaAs. Time-resolved photoluminescence of the CdTe/MgCdTe DH gives a Shockley-Read-Hall recombination lifetime of 86 ns, which is more than one order of magnitude longer than that of typical polycrystalline CdTe films. These findings indicate that monocrystalline CdTe/MgCdTe DHs effectively reduce surface recombination, have limited nonradiative interface recombination, and are promising for solar cells that could reach power conversion efficiencies similar to that of GaAs.
Chirped laser dispersion spectroscopy using a directly modulated quantum cascade laser
Authors: Hangauer Andreas , Spinner Georg , Nikodem Michal , Wysocki Gerard
Published: November 2013

Chirped laser dispersion spectroscopy (CLaDS) utilizing direct modulation of a quantum cascade laser (QCL) is presented. By controlling the laser bias nearly single- and dual-sideband CLaDS operation can be realized in an extremely simplified optical setup with no external optical modulators. Capability of direct single-sideband modulation is a unique feature of QCLs that exhibit a low linewidth enhancement factor. The developed analytical model shows excellent agreement with the experimental, directly modulated CLaDS spectra. This method overcomes major technical limitations of mid-infrared CLaDS systems by allowing significantly higher modulation frequencies and eliminating optical fringes introduced by external modulators.
Dynamical properties of non-ideal plasma on the basis of effective potentials
Authors: Ramazanov T. S. , Kodanova S. K. , Moldabekov Zh. A. , Issanova M. K.
Published: November 2013

In this work, stopping power has been calculated on the basis of the Coulomb logarithm using the effective potentials. Calculations of the Coulomb logarithm and stopping power for different interaction potentials and degrees of ionization are compared. The comparison with the data of other theoretical and experimental works was carried out.
Wake-up effects in Si-doped hafnium oxide ferroelectric thin films
Authors: Zhou Dayu , Xu Jin , Li Qing , Guan Yan , Cao Fei , Dong Xianlin , Müller Johannes , Schenk Tony , Schröder Uwe
Published: November 2013

Hafnium oxide based ferroelectric thin films have shown potential as a promising alternative material for non-volatile memory applications. This work reports the switching stability of a Si-doped HfO2 film under bipolar pulsed-field operation. High field cycling causes a “wake-up” in virgin “pinched” polarization hysteresis loops, demonstrated by an enhancement in remanent polarization and a shift of negative coercive voltage. The rate of wake-up is accelerated by either reducing the frequency or increasing the amplitude of the cycling field. We suggest de-pinning of domains due to reduction of the defect concentration at bottom electrode interface as origin of the wake-up.
Magnetic interactions in the martensitic phase of Mn rich Ni-Mn-In shape memory alloys
Authors: Lobo D. N. , Dwivedi Sandhya , daSilva C. A. , Moreno N. O. , Priolkar K. R. , Nigam A. K.
Published: November 2013

The magnetic properties of Mn2Ni(1+x)In(1−x) (x = 0.5, 0.6, 0.7) and Mn(2−y)Ni(1.6+y)In0.4 (y = −0.08, −0.04, 0.04, 0.08) shape memory alloys have been studied. Magnetic interactions in the martensitic phase of these alloys are found to be quite similar to those in Ni2Mn(1+x)In(1−x) type alloys. Doping of Ni for In not only induces martensitic instability in Mn2NiIn type alloys but also affects magnetic properties due to a site occupancy disorder. Excess Ni preferentially occupies X sites forcing Mn to the Z sites of X2YZ Heusler composition resulting in a transition from ferromagnetic ground state to a state dominated by ferromagnetic Mn(Y)-Mn(Y) and antiferromagnetic Mn(Y)-Mn(Z) interactions. These changes in magnetic ground state manifest themselves in observation of exchange bias effect even in zero field cooled condition and virgin magnetization curve lying outside the hysteresis loop.
Enhanced ferromagnetism in CuO nanowires on the top of CuO nanograins
Authors: Souza J. A. , Criado D. , Zuniga A. , Miranda V. N. , Ramirez F. E. N. , Masunaga S. H. , Jardim R. F.
Published: November 2013

CuO nanograins (NGs) and CuO nanowires (NWs) on the top of nanograins samples were produced by the electrical resistive heating method. The NGs sample shows absence of long range magnetic order and strong field-induced ferromagnetic behavior. In the sample comprised of NWs on the top of NGs, a long-ranged antiferromagnetic ordering is induced by a magnetic field of 5 kOe and coexists with an enhanced ferromagnetic-like contribution. The ferromagnetic behavior is observed below and above the temperature-induced TN suggesting that this behavior is not dependent on the original magnetic state of the system, whether it is paramagnetic (PM) or antiferromagnetic.