bluuebunny/crossref_metadata_2025 huggingface dataset:
Megalencephaly Capillary Malformation Syndrome
Authors: Polizzi Agata , Salafia Stefania , Praticò Elena , Garozzo Maria , Sullo Federica , Catanzaro Stefano , Belfiore Giuseppe , Pirrone Concetta , Zanghì Antonio , Fiumara Agata , Ruggieri Martino , Resta Nicoletta , Praticò Andrea
Published: August 2018

Megalencephaly capillary malformation polymicrogyria (MCAP) syndrome is characterized by the sporadic occurrence of congenital and progressive megalencephaly, brain malformations including polymicrogyria, pre- and postnatal overgrowth with body asymmetry, cutaneous vascular malformations (including capillary malformation and cutis marmorata), digital anomalies connective tissue dysplasia (including skin and joint laxity), and developmental delay. In the past 10 years, the specific cause of the disease has been found in gain-of-function mutations of PIK3CA gene, mostly somatic/postzygotic but in rare cases also de novo germline. Such gene encodes for PI3K, a critical member of the PI3K-AKT-mTOR pathway: genetic changes lead to an over-activation of this signaling system, with increased vascular, limb, and brain cell development, progression, and survival. Interestingly, mutations in the same gene can cause other clinically heterogeneous syndromes, including CLOVE syndrome, macrodactyly, focal adipose overgrowth, epidermal nevi, facial infiltrating lipomatosis: all these syndromes (even if heterogeneous) are now considered a unique spectrum, known as PIK3CA-related overgrowth syndrome. On the contrary, a disease strictly similar to MCAP, characterized by megalencephaly, polymicrogyria, polydactyly, and hydrocephalus has been found to be caused by mutations in two other PI3K-AKT-mTOR-releted genes, AKT3 and PIK3R2, and for this reason is not included in the upper mentioned group of syndromes. With the exception of neurosurgery strategies for hydrocephalus and posterior fossa overcrowding, therapeutic options are nowadays limited, even if gene-targeted treatment protocols have been proposed and protocols with such agents (i.e., Arq092) are currently ongoing in small groups of patients with promising results.
Cerebellotrigeminal Dermal Dysplasia (Gómez-López-Hernández Syndrome)
Authors: Sullo Federica , Polizzi Agata , Catanzaro Stefano , Mantegna Selene , Lacarrubba Francesco , Micali Giuseppe , Fiumara Agata , Smilari Pierluigi , Greco Filippo , Schepis Carmelo , Pirrone Concetta , Zanghì Antonio , Pascual-Castroviejo Ignacio , Ruggieri Martino , Praticò Andrea
Published: August 2018

Cerebellotrigeminal dermal (CTD) dysplasia is a rare neurocutaneous disorder characterized by a triad of symptoms: bilateral parieto-occipital alopecia, facial anesthesia in the trigeminal area, and rhombencephalosynapsis (RES), confirmed by cranial magnetic resonance imaging. CTD dysplasia is also known as Gómez-López-Hernández syndrome. So far, only 35 cases have been described with varying symptomatology. The etiology remains unknown. Either spontaneous dominant mutations or de novo chromosomal rearrangements have been proposed as possible explanations. In addition to its clinical triad of RES, parietal alopecia, and trigeminal anesthesia, CTD dysplasia is associated with a wide range of phenotypic and neurodevelopmental abnormalities.

Treatment is symptomatic and includes physical rehabilitation, special education, dental care, and ocular protection against self-induced corneal trauma that causes ulcers and, later, corneal opacification. The prognosis is correlated to the mental development, motor handicap, corneal–facial anesthesia, and visual problems. Follow-up on a large number of patients with CTD dysplasia has never been reported and experience is limited to few cases to date. High degree of suspicion in a child presenting with characteristic alopecia and RES has a great importance in diagnosis of this syndrome.
Speckled Lentiginous Nevus Syndrome
Authors: Marino Simona , Venti Valeria , Mendola Flavia , Garozzo Maria , Polizzi Agata , Pirrone Concetta , Lacarrubba Francesco , Micali Giuseppe , Quattrocchi Enrica , Schepis Carmelo , Zanghì Antonio , Praticò Elena , Pascual-Castroviejo Ignacio , Ruggieri Martino , Praticò Andrea
Published: August 2018

Speckled lentiginous nevus syndrome is a rare neurocutaneous phenotype, characterized by a specked lentiginous nevus, appearing as a light brown macule superimposed by multiple melanocytic nevi in the form of macules or papules with uneven distribution, associated with ipsilateral neurological and musculoskeletal abnormalities (i.e., dysesthesia, hyperhidrosis, and musculoskeletal abnormalities) occur. It represents a mosaic phenotype disorder resulting from postzygotic loss of heterozygosity, due to a localized defect in neural crest melanoblasts that originate certain areas of the skin and some ipsilateral neurological and musculoskeletal cells. Environmental and genetic factors may also play a role, but it has not been clarified how these factors behave in this syndrome.
Nevus Sebaceous Syndrome
Authors: La Mendola Flavia , Catanzaro Stefano , Polizzi Agata , Schepis Carmelo , Pirrone Concetta , Zanghì Antonio , Salafia Stefania , Ruggieri Martino , Lacarrubba Francesco , Micali Giuseppe , Verzì Anna , Sugarman Jeffrey , Praticò Andrea
Published: August 2018

Nevus sebaceous (NS) is a hamartomatous disorder of the skin and adjacent tissues characterized by epidermal, follicular, sebaceous, and apocrine gland abnormalities. It occurs in approximately 1 in 1,000 live births. A hyperactivation of Ras pathways has been recently assumed to be the cause of this phenotype. NS lesions may be isolated or coupled with extracutaneous manifestations, mostly of the central nervous, ocular, and skeletal systems, or kidneys; in this case, the term “NS syndrome” is used. Cutaneous distribution of NS usually follows the linear patterns known as “lines of Blaschko,” with lines that do not follow the segmental trajectory of the peripheral sensory nerves but instead reflect the streams or trends of growth of embryonic tissues. Histological characteristics of the lesions appear to be actually more decisive than the clinical evaluation to distinguish between the types of epidermal nevus: the typical NS has both papillated epidermal hyperplasia and a predominance of subjacent abnormal follicular–sebaceous glands.

Seizures, mental retardation, and/or cognitive developmental delay are the most common neurologic abnormalities associated with NS and usually are present within the first months of life; eye and skeletal involvement may be present as well.

The definitive treatment of NS is full-thickness excision. However, the necessity and timing of excision to prevent possible future malignancy are not clear; lasers and photodynamic therapy are alternatives currently being explored for the treatment of NS, with varying degrees of success.
Adoption of Electronic Dental Records: Examining the Influence of Practice Characteristics on Adoption in One State
Authors: Chauhan Zain , Samarah Mohammad , Unertl Kim , Jones Martha
Published: August 2018

Objective Compared with medicine, less research has focused on adoption rates and factors contributing to the adoption of electronic dental records (EDRs) and certified electronic health records (EHRs) in the field of dentistry. We ran two multivariate models on EDR adoption and certification-capable EHR adoption to determine environmental and organizational factors associated with adoption.

Methods We conducted telephone survey of a 10-item questionnaire using disproportionate stratified sampling procedure of 149 dental clinics in Tennessee in 2017 measuring adoption of dental information technology (IT) (EDRs and certification-capable EHRs) and practice characteristics, including region, rurality, specialty, and practice size. We used binomial logistic regression models to determine associations of adoption with predictor variables.

Results A total of 77% of surveyed dental clinics in Tennessee had adopted some type of EDR system. When the definitions of certification capable were applied, the adoption rates in dental clinics dropped to 58%. A binomial logistic regression model for the effects of rurality, specialization, and practice size on the likelihood that a clinic would adopt an EHR product was statistically significant (chi-square (3) = 12.41, p = 0.0061). Of the three predictor variables, specialization and practice size were significant: Odds of adopting an EHR is 67% lower for specialists than for general dentists; and clinics with two or more practicing dentists were associated with a much greater likelihood of adopting an EHR-capable system (adjusted odds ratio = 3.09, p = 0.009).

Conclusion Findings from this study indicate moderate to high levels of overall dental IT adoption. However, adoption rates in dental clinics do remain lower than those observed in office-based physician practices in medicine. Specialization and practice size were significant predictors of EHR-capable system adoption. Efforts to increase EHR adoption in dentistry should be mindful of potential disparities in smaller practices and between dental specialties and generalists.
Pie Crust Technique of the Deep Medial Collateral Ligament in Knee Arthroscopy: Ultrasound and Anatomic Study
Authors: Claret-Garcia Guillem , Montañana-Burillo Jordi , Tornero-Dacasa Eduard , Llusá-Pérez Manel , Popescu Dragos , Combalia-Aleu Andreu , Sastre-Solsona Sergi
Published: August 2018

This article determines compartment opening of the medial articular space of the knee after pie crust (PC) technique of the medial collateral ligament (MCL) by ultrasound measurements and anatomic dissection. This is a cadaveric study of 12 specimens. Four anatomic references were marked on the skin. Distances between the femur and tibia in the internal compartment at 30 degrees of flexion were obtained with ultrasound measurements in four situations: with and without applying valgus force both prior and after the PC technique. Ultrasound measurements of the medial articular compartment were made twice and mean value was calculated. An anatomical dissection was performed and distances between the puncture marks and the infrapatellar branch of the saphenous nerve was measured. Lilliefors test of normality was applied and variables were expressed as mean and standard deviation (SD). Qualitative variables were expressed by absolute frequencies and percentages. Statistical significance was a two-tailed p-value of < 0.05. Prior to the PC technique, mean (SD) distance between the femur and tibia in the medial compartment were 14.2 (4.0) mm in basal conditions and 17.1 (3.7) mm when applying valgus force (p = 0.003). PC technique increased the mean (SD) distance by 1.9 (1.9) mm under basal conditions (p < 0.01) and 2.9 (1.6) mm when applying valgus force (p < 0.01). The infrapatellar branches of the saphenous nerve were not damaged and the mean (SD) distance between the punctures and the nerve was 9.0 (3.3) mm. The PC is a reproducible, safe, and measurable surgical technique that opens controllably the medial compartment. PC as described avoided damage to the nerve branches.
Surgery for Pediatric Ureteropelvic Junction Obstruction—Comparison of Outcomes in Relation to Surgical Technique and Operating Discipline in Germany
Authors: Klora M. , Zeidler J. , Eberhard S. , Bassler S. , Mayer S. , Gosemann J.-H. , Lacher M. , Goetz G.
Published: August 2018

Introduction Surgery for ureteropelvic junction obstruction (UPJO) is performed by both pediatric surgeons (PS) and urologists (URO). The aim of this study was to analyze treatment modalities for UPJO and results in relation to the surgical technique and the operating discipline in Germany.

Materials and Methods Data of patients aged 0 to 18 years were extracted from a major public health insurance (covering ∼5.7 million clients) during 2009 to 2016 and were analyzed for sociodemographic variables, surgical technique, and treating discipline. Logistic regression analysis was performed for the risk of a complication within the first postoperative year.

Results A total of 229 children (31.0% female) were included. Laparoscopic pyeloplasty (LP) was performed in 58 (25.3%) patients (8.6 ± 6.4 years), and open pyeloplasty (OP) was applied in 171 (74.7%; 4.6 ± 5.9 years). LP was the dominant technique in females (p < 0.02); males preferentially underwent OP (p < 0.02). Length of hospital stay was 4.3 days (p = 0.0005) shorter in LP compared with that in OP, especially in children ≤ 2 years (6.7 days, p = 0.007). PS operated on 162 children (70.7%), and URO performed surgery on 67 patients (29.3%). The mean age of children operated by PS (3.5 ± 4.7 years) was significantly younger compared with that operated by URO (10.8 ± 6.5 years, p < 0.0001). Complication rates were independent of surgical technique or treating specialty.

Conclusion In Germany, UPJO was treated by LP in 25.3% of patients, which was associated with a shorter length of stay, especially in children ≤ 2 years. Complication rates were independent of the operating specialty and surgical technique. Therefore, LP should be further promoted for the treatment of UPJO in small children.
Quantification of Platelet Contractile Movements during Thrombus Formation
Authors: Tunströmer Kjersti , Faxälv Lars , Boknäs Niklas , Lindahl Tomas
Published: August 2018

Imaging methods based on time-lapse microscopy are important tools for studying the dynamic events that shape thrombus formation upon vascular injury. However, there is a lack of methods to translate the vast amount of visual data generated in such experiments into quantitative variables describing platelet movements that can be subjected to systematic analysis. In this study, we developed experimental and computational protocols allowing for a detailed mathematical analysis of platelet movements within a developing thrombus. We used a flow chamber-based model of thrombosis wherein a collagen strip was used to initiate platelet adhesion and activation. Combining the use of a platelet staining protocol, designed to enable identification of individual platelets, and image processing, we tracked the movements of a large number of individual platelets during thrombus formation and consolidation. These data were then processed to generate aggregate measures describing the heterogeneous movements of platelets in different areas of the thrombus and at different time points. Applying this model and its potential, to a comparative analysis on a panel of platelet inhibitors, we found that total platelet intra-thrombus movements are only slightly reduced by blocking the interactions between glycoproteins IIb/IIIa and Ib and their ligands or by inhibiting thromboxane synthesis or P2Y12 signalling. In contrast, whereas 30 to 40% of the platelets movements (for the CD42a-labelled platelets) and 20% (for the pro-coagulant platelets), within a thrombus, are contractile, i.e., towards the centre of the thrombus, this contractile component is almost totally abolished in the presence of agents inhibiting these pathways.
Non- or Minimally Displaced Distal Radial Fractures in Adult Patients: Three Weeks versus Five Weeks of Cast Immobilization—A Randomized Controlled Trial
Authors: Bentohami A. , Vermeulen J. , Sosef N. L. , de Korte N. , Bijlsma T. S. , Goslings J. C. , Schep N. W. L. , van Delft E.
Published: August 2018

Background Patients with non- or minimally displaced distal radial fractures, that do not need repositioning, are mostly treated by a short-arm cast for a period of 4 to 6 weeks. A shorter period of immobilization may lead to a better functional outcome.

Purpose We conducted a randomized controlled trial to evaluate whether the duration of cast immobilization for patients with non- or minimally displaced distal radial fractures can be safely shortened toward 3 weeks.

Materials and Methods The primary outcomes were patient-reported outcomes measured by the Patient-Related Wrist Evaluation (PRWE) and Quick Disability of Arm, Shoulder and Hand (QuickDASH) score after 1-year follow-up. Secondary outcome measures were: PRWE and QuickDASH earlier in follow-up, pain (Visual Analog Scale), and complications like secondary displacement.

Results Seventy-two patients (male/female, 23/49; median age, 55 years) were included and randomized. Sixty-five patients completed the 1-year follow-up. After 1-year follow up, patients in the 3 weeks immobilization group had significantly better PRWE (5.0 vs. 8.8 points, p = 0.045) and QuickDASH scores (0.0 vs. 12.5, p = 0.026). Secondary displacement occurred once in each group. Pain did not differ between groups (p = 0.46).

Conclusion Shortening the period of immobilization in adult patients with a non- or minimally displaced distal radial fractures seems to lead to equal patient-reported outcomes for both the cast immobilization groups. Also, there are no negative side effects of a shorter period of cast immobilization. Therefore, we recommend a period of 3 weeks of immobilization in patients with distal radial fractures that do not need repositioning.
Preoperative Assessment of Coronary Arteries by Cardiac Computed Tomography in Patients with Lung Cancer
Authors: Zhang Fan , Chen Jing , Yang Zhi-Gang , Liu Han
Published: August 2018

Background To retrospectively evaluate characteristics of coronary artery disease (CAD) in patients undergoing lung resection for cancer by using dual-source computed tomography (DSCT), thus increasing our understanding of perioperative evaluation.

Methods DSCT coronary angiography was performed for perioperative evaluation in 145 patients with non-small cell lung cancer (NSCLC) due to suspected CAD. The imaging characteristics of CAD including extent, distribution and types of plaques, and luminal stenosis and congenial anomalous including origin of coronary arteries and myocardial bridge (MB) were evaluated and compared by sex, smoking behavior, and pathological types.

Results In total, coronary artery plaques were observed in 130 (89.7%) patients. A total of 205 coronary vessels (1.7 ± 1.3 per patient) and 278 segments (2.4 ± 2.3 per patient) were found to have plaques, respectively. The most frequently involved segment were the left anterior descending (LAD) artery (45.4%) and its proximal segment (24.1%) (p < 0.05). Mild narrowing (61.7%) and calcified plaques (52.9%) were most found (all p < 0.001). Types of plaques, luminal narrowing and extent were not significantly different by sex, smoking behavior, or pathological type. Anomalous origination of the right coronary ostium from left sinus was observed in 0.7% of patients. MB was observed in 16.6% of patients.

Conclusion Dual-source CT is a useful preoperative noninvasive test for CAD in patients planning to undergo lung resection for cancer.
Analytical Considerations in Nanoscale Flow Cytometry of Extracellular Vesicles to Achieve Data Linearity
Authors: Gomes Janice , Lucien Fabrice , Cooper Tyler , Kim Yohan , Williams Karla , Liao XinYang , Kaufman Lauren , Lagugné-Labarthet Francois , Kenyon Oliver , Boysen Justin , Kay Neil , McIntyre Christopher , Leong Hon
Published: August 2018

Background Platelet microparticles (PMPs) and their abundance in the blood are a prognostic biomarker in thrombotic disorders and cancer. Nanoscale flow cytometry (nFC) is ideal for high-throughput analysis of PMPs but these clinical assays have not been developed previously.

Objective This article demonstrates that nFC is a suitable technology to enumerate PMPs present in plasma samples in a clinical setting.

Materials and Methods nFC was performed using the Apogee A50-Micro instrument. Instrument settings and acquisition parameters were developed with the use of fluorescent beads and plasma samples. Sample preparation and handling was also optimized.

Results nFC allows for linear detection of particles between approximately 200 and 1,000 nm based on calibration beads and was dependent on dilution factor and flow rate. Linearity in event analysis as samples became more diluted was lost when events approximately 100 nm were gated while linearity was maintained despite dilution of sample in events larger than 200 nm in diameter. Higher flow rates lead to an under-estimation of events analysed per microlitre of analyte and this was more pronounced when plasma samples were not diluted more than 1/20×.

Conclusion nFC offers multi-parametric analysis of PMPs when optimal calibration of acquisition and sample processing settings is performed. Analysis of plasmas from metastatic prostate cancer patients and leukaemia patients revealed that PMP levels were larger than 100 nm and were equally abundant in patients that responded to or failed androgen deprivation therapy or between patients representing different stages of leukaemia.
Interplay of the unit-speed constraint and time-delay in Cucker-Smale flocking
Authors: Choi Sun-Ho , Ha Seung-Yeal
Published: August 2018

We study the emergence of the mono-cluster flocking due to the interplay between the unit-speed constraint and time-delayed interactions in the evolution of the Cucker-Smale ensemble. Several flocking models with unit-speed constraint have been extensively used in the flocking modeling of self-propelled multi-agent systems in the control theory community. Time-delayed interactions can be caused by the finite propagation speed constraint in communications. In the previous literature, these two physical mechanisms have been studied separately. In this paper, we investigate these combined physical effects in a common framework and study how the interplay between these mechanisms affects asymptotic flocking dynamics. For this, we provide a sufficient framework for a mono-cluster flocking in terms of system parameters (e.g., time-delay, coupling strength, particle numbers) and initial data. We also provide several numerical simulations and compare them with analytical results.
The log-Sobolev inequality with quadratic interactions
Authors: Papageorgiou Ioannis
Published: August 2018

We assume one-site measures without a boundary e−ϕ(x)dx/Z that satisfies a log-Sobolev inequality. We prove that if these measures are perturbed with quadratic interactions, then the associated infinite dimensional Gibbs measure on the lattice always satisfies a log-Sobolev inequality. Furthermore, we present examples of measures that satisfy the inequality with a phase that goes beyond convexity at infinity.
Epitaxial LaFeO3 and LaFe0.75Zn0.25O3 thin films on SrTiO3 (STO) (100) substrate: Structural studies and high energy magnon excitations
Authors: Manzoor Samiya , Husain Shahid , Raghavendra Reddy V.
Published: August 2018

The epitaxial films of LaFeO3 (LFO) and LaFe0.75Zn0.25O3 (LFZO) are grown on a SrTiO3 (STO) (100) substrate using pulsed laser deposition. The as-grown films have been investigated to study the structural properties and magnon excitations using temperature dependent Raman spectroscopy. X-ray diffraction and high resolution x-ray diffraction reciprocal space mapping indicate the epitaxial growth of films on the STO (100) substrate. RSM shows the broadening of the diffraction spot in the qz direction that may be due to the tilt present in the thin films, suggesting the orthorhombic growth of the films. Raman measurements on LFO and LFZO thin films have been performed for structure identification. The absence of first order phonon modes in Raman spectra suggests that the structure of films is symmetric and is coherent with the cubic substrate. High energy Raman bands with typical characteristics of two-magnon scattering appear below Neel temperature. Splitting of magnon branches is seen for both LFO and LFZO films and has been analyzed on the basis of the magnetic structure of LFO. The hardening of the magnon modes is observed as the temperature approaches towards the Neel temperature that may be attributed to the lattice contraction and correlated with a decrease in the tilt and a corresponding increase in the Heisenberg exchange constant (J) leading to a more ordered state at Neel temperature.
Triplet-triplet annihilation in a thermally activated delayed fluorescence emitter lightly doped in a host
Authors: Niwa Akitsugu , Haseyama Shota , Kobayashi Takashi , Nagase Takashi , Goushi Kenichi , Adachi Chihaya , Naito Hiroyoshi
Published: August 2018

Triplet-triplet annihilation (TTA) will change the ratio between fluorescence and phosphorescence in the photoluminescence spectrum of a thermally activated delayed fluorescence emitter at very low temperature. Using the resultant spectral blueshift, this study investigated the nature of TTA in 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) doped in a host material. The spectral blueshift is not caused by singlet-triplet annihilation and the emitter saturation effect and is less influenced by the emitter aggregates, particularly for the case of a lower doping concentration. Using these features, it is possible to focus on TTA. For 4CzIPN, the spectral blueshift due to TTA is recognized even in samples with the doping concentration as low as 1 wt. %.
Femtosecond laser crystallization of amorphous titanium oxide thin films
Authors: Hoppius Jan S. , Bialuschewski Danny , Mathur Sanjay , Ostendorf Andreas , Gurevich Evgeny L.
Published: August 2018

In this paper, we demonstrate experimentally that crystalline phases appear in amorphous titanium oxide upon processing with ultrafast laser pulses. Amorphous titanium thin films were produced by plasma-enhanced chemical vapor deposition and exposed to femtosecond laser pulses. Formation of a rutile phase was confirmed by X-ray diffraction, Raman measurements, and electron backscattering diffraction. A range of processing parameters for the crystallization is reported, and possible background mechanisms are discussed.
Feasibility of transition radiation as a diagnostic of hot electrons generated in indirect-drive experiment
Authors: Liu Yaoyuan , Ding Yongkun , Zheng Jian
Published: August 2018

In the experiment of indirect-drive inertial confinement fusion, hot electrons in hohlraum are usually inferred from the bremsstrahlung, measured with filter-fluoresce X-ray spectrometer. Here, we study the feasibility of measuring hot electrons by detecting the transition radiation, emitted from energetic electrons passing through the outer surface of hohlraum. With the aid of Monte Carlo simulations, it was found that the intensity of black-body radiation in optical range, due to the energy deposition of electrons, is at least one order of magnitude larger than that of optical transition radiation, but two orders of magnitude smaller than the intensity in THz range. Hence, it would be plausibly feasible to detect the transition radiation in the far infrared and THz range. Furthermore, the sensitivity of intensity versus thickness and temperature are discussed with two temperature components of hot electrons. Finally, a proposal of diagnostic for hot electrons is put forward by adopting the wedge or stepped plate.
Dynamic bounds on stochastic chemical kinetic systems using semidefinite programming
Authors: Dowdy Garrett R. , Barton Paul I.
Published: August 2018

Applying the method of moments to the chemical master equation appearing in stochastic chemical kinetics often leads to the so-called closure problem. Recently, several authors showed that this problem can be partially overcome using moment-based semidefinite programs (SDPs). In particular, they showed that moment-based SDPs can be used to calculate rigorous bounds on various descriptions of the stochastic chemical kinetic system’s stationary distribution(s)—for example, mean molecular counts, variances in these counts, and so on. In this paper, we show that these ideas can be extended to the corresponding dynamic problem, calculating time-varying bounds on the same descriptions.
Structural, electronic, vibrational, and superconducting properties of hydrogenated chlorine
Authors: Durajski Artur P. , Szczȩśniak Radosław
Published: August 2018

Recent measurements have set a new record for the superconducting transition temperature (Tc) at which a material losses electrical resistivity and exhibits ideal diamagnetism. Theory-oriented experiments show that the compressed hydride of Group VI (hydrogen sulfide, H3S) exhibits a superconducting state at 203 K. Moreover, a Group V hydride (phosphorus hydride, PH3) has also been studied and its Tc reached a maximum of 103 K. The experimental realisation of the superconductivity in H3S and PH3 inspired us to search for other hydride superconductors. Herein, we report theoretical studies of the electronic, vibrational, and superconducting properties of hydrogenated chlorine (H3Cl, representative of the Group VII hydride). First-principles calculations performed for H3Cl in the pressure range 150–250 GPa show that the investigated Im3¯m phase has a large electron-phonon coupling parameter and the resulting application of the Migdal-Eliashberg formalism yields a remarkably high superconducting temperature of 198 K at 150 GPa.
Pervasive interactions between methyl torsion and low frequency vibrations in S and S1 p-fluorotoluene
Authors: Gascooke Jason R. , Stewart Laurence D. , Sibley Paul G. , Lawrance Warren D.
Published: August 2018

We report two dimensional laser induced fluorescence spectral images exploring the lower torsion-vibration manifolds in S0 (E < 560 cm−1) and S1 (E < 420 cm−1) p-fluorotoluene. Analysis of the images reveals strong torsion-vibration interactions and provides an extensive set of torsion-vibration state energies in both electronic states (estimated uncertainty ±0.2 cm−1), which are fit to determine key constants including barrier heights, torsional constants, and torsion-vibration interaction constants. The dominant interactions in both electronic states are between methyl torsion (internal rotation) and the lowest frequency out-of-plane modes, D20 and D19, both of which involve a methyl wagging motion. This is the second aromatic (following toluene) for which a significant interaction between torsion and methyl out-of-plane wagging vibrations has been quantified. Given the generic nature of this motion in substituted toluenes and similar molecules, this mechanism for torsion-vibration coupling may be common in these types of molecules. The inclusion of torsion-vibration coupling affects key molecular constants such as barrier heights and torsional (and rotational) constants, and the possibility of such an interaction should thus be considered in spectral analyses when determining parameters in these types of molecules. p-Fluorotoluene is the first molecule in which the role of methyl torsion in promoting intramolecular vibrational energy redistribution (IVR) was established and the observed torsion-vibration coupling provides one conduit for the state mixing that is a precursor to IVR, as originally proposed by Moss et al. [J. Chem. Phys. 86, 51 (1987)].
Comment on “The collision effect between dust grains and ions to the dust ion acoustic waves in a dusty plasma” [Phys. Plasmas 19, 103705 (2012)]
Authors: Mandi Laxmikanta , Saha Asit , Chatterjee Prasanta
Published: August 2018

The paper by Yang et al. [Phys. Plasmas 19, 103705 (2012)] contains some errors which have been pointed out in this Comment. They did not normalize all the independent and dependent variables, but to derive the nonlinear evolution equation (KdV-type equation), they expanded dependent variables around their equilibrium values which is not correct. The KdV-type equation obtained in the work [Phys. Plasmas 19, 103705 (2012)] is not correct. To conclude, both the qualitative and quantitative results obtained in the work related to the KdV-type equation are not correct and realistic.
Electric field controlled spin waveguide phase shifter in YIG
Authors: Wang Xi-guang , Chotorlishvili L. , Guo Guang-hua , Berakdar J.
Published: August 2018

We propose a new type of a spin waveguide in yttrium iron garnet solely controlled by external electric fields. Spin waves are generated by microwave electric fields while the shift of the phase between spin waves is achieved by means of static electric fields. The phase shifter operation is based on the magneto-electric coupling and effective Dzyaloshinskii Moriya interaction. The special geometry of the waveguide imposes certain asymmetry in the dispersion relationships of the spin waves. Depending on the propagation direction, the phases of the spin waves are shifted differently by the external electric field. The phase difference is entirely controlled by the driving electric fields. The proposed phase shifter can be easily incorporated into electronic circuits and in spin wave logical operations.
A vapor-cell atomic sensor for radio-frequency field detection using a polarization-selective field enhancement resonator
Authors: Anderson D. A. , Paradis E. G. , Raithel G.
Published: August 2018

We present a hybrid atomic sensor that realizes radio-frequency electric field detection with intrinsic field enhancement and polarization selectivity for robust high-sensitivity field measurement. The sensor incorporates a passive resonator element integrated with an atomic vapor cell that provides enhancement and polarization selectivity of incident radio-frequency fields. The enhanced intra-cavity radio-frequency field is measured by atoms using a quantum-optical readout of AC level shifts of field-sensitive atomic Rydberg states. In our demonstration, we employ a split field-enhancement resonator embedded in a rubidium vapor cell to enhance and detect C-band radio-frequency fields. We observe a field enhancement equivalent to a 24 dB gain in intensity sensitivity. The spatial profile of the resonant field mode inside the field-enhancement cavity is characterized and robust polarization measurement of the incident field is demonstrated. The measured performance metrics of the sensor are in good agreement with simulations. Applications of such atomic sensors in ultra-weak radio-frequency detection and advanced measurement capabilities are discussed.
Franz-Keldysh effect in semiconductor built-in fields: Doping concentration and space charge region characterization
Authors: Turkulets Yury , Shalish Ilan
Published: August 2018

Franz-Keldysh effect is expressed in the smearing of the absorption edge in semiconductors under high electric fields. While Franz [Z. Naturforsch. A 13, 484 (1958)] and Keldysh [Sov. Phys. JETP 7, 788 (1958)] considered a limited case of externally applied uniform electric field, the same effect may also be caused by built-in electric fields at semiconductor surfaces and interfaces. While in the first case, the bands are bent linearly, in the latter case, they are bent parabolically. This non-linear band bending poses an additional complexity that has not been considered previously. Here, we extend the linear model to treat the case of a non-linear band bending. We then show how this model may be used to quantitatively analyze photocurrent and photovoltage spectra to determine the built-in fields, the density of surface state charge, and the doping concentration of the material. We use the model on a GaN/AlGaN heterostructure and GaAs bulk. The results demonstrate that the same mechanism underlies the band-edge response both in photocurrent and photovoltage spectra and demonstrate the quantitative use of the model in contactless extraction of important semiconductor material parameters.
Using L-shell x-ray spectra to determine conditions of non-local thermal dynamic equilibrium plasmas
Authors: Marley E. V. , Liedahl D. A. , Schneider M. B. , Heeter R. F. , Jarrott L. C. , Mauche C. W. , Kemp G. E. , Foord M. E. , Frank Y. , Widmann K. , Emig J.
Published: August 2018

K-shell x-ray spectra of Li- to H-like ions have long been used to determine plasma conditions. The ratio of integrated line intensities is used to determine the temperature. At the density of non-local thermal dynamic equilibrium (NLTE) plasmas (ne ≈ 1021 cm−3), the K-shell spectrum is not very sensitive to density. We propose using the L-shell emission of open L-shell ions (C- to Li-like) as an alternative to determine both temperature and density of NLTE plasmas. First, the L-shell models of a mid-Z material need to be verified against the temperatures obtained using a K-shell spectrum of a low-Z material. A buried layer platform is being developed at the OMEGA laser to study the open L-shell spectra of NLTE plasmas of mid-Z materials. Studies have been done using a 250 μm diameter dot composed of a layer of 1200 Å thick Zn between two 600 Å thick layers of Ti, in the center of a 1000 μm diameter, 13 μm thick beryllium tamper. Lasers heat the target from both sides for up to 3 ns. The size of the emitting volume vs time was measured with x-ray imaging (face-on and side-on) to determine the density. The temperature was measured from the Ti K-shell spectra. The use of this platform for the verification of atomic L-shell models is discussed.
Broadband efficient vortex beam generation with metallic helix array
Authors: Gong Zhijie , Wu Chao , Fang Chaoqun , Zhao Song , Sun Anqi , Wei Zeyong , Li Hongqiang
Published: August 2018

Vortex beams with orbital angular momentum are characterized by a helical phase front and a phase singularity at the beam center. Such beams have various intriguing applications, such as optical communications, particle trapping, and high resolution imaging. Generating a vortex beam by exploiting the geometric phase has attracted great interest, due to its spin-to-orbital conversion feature and device versatility. To meet the requirements of applications such as optical communications and make the devices more user-friendly, vortex beam generation needs to be efficient in a large frequency range. The efficient bandwidth of the optical element is critical here, since the geometric phase is frequency independent. In this work, we design and fabricate a broadband efficient reflective vortex beam generator based on a metallic helix array, which has a uniform efficient co-circular-polarization reflection property. Vortex beams with arbitrary topological charge can be generated with such devices. The measured efficiency of our device is above 58.4%, with the relative bandwidth of 64.52%.
Quantum photonic integrated circuits based on tunable dots and tunable cavities
Authors: Petruzzella M. , Birindelli S. , Pagliano F. M. , Pellegrino D. , Zobenica Ž. , Li L. H. , Linfield E. H. , Fiore A.
Published: August 2018

Quantum photonic integrated circuits hold great potential as a novel class of semiconductor technologies that exploit the evolution of a quantum state of light to manipulate information. Quantum dots encapsulated in photonic crystal structures are promising single-photon sources that can be integrated within these circuits. However, the unavoidable energy mismatch between distant cavities and dots, along with the difficulties in coupling to a waveguide network, has hampered the implementation of circuits manipulating single photons simultaneously generated by remote sources. Here we present a waveguide architecture that combines electromechanical actuation and Stark-tuning to reconfigure the state of distinct cavity-emitter nodes on a chip. The Purcell-enhancement from an electrically controlled exciton coupled to a ridge waveguide is reported. Besides, using this platform, we implement an integrated Hanbury-Twiss and Brown experiment with a source and a splitter on the same chip. These results open new avenues to scale the number of indistinguishable single photons produced on-demand by distinct emitters.
A U-shaped multi-modal bi-directional piezoelectric energy harvester
Authors: Su Wei-Jiun , Shih Hsuan-An
Published: August 2018

A conventional piezoelectric energy harvester suffers from narrow bandwidth and uni-directional harvesting. This paper presents a U-shaped multi-modal bi-directional piezoelectric energy harvester to overcome the above issues. The U-shaped structure, composed of a main beam and two identical side beams, can be fabricated by bending a beam into a U shape with both ends clamped. The theoretical model of the U-shaped piezoelectric energy harvester is developed and validated with experimental results. This U-shaped piezoelectric energy harvester demonstrates the capability of harvesting vibration energy in both the vertical and horizontal directions, which are the transverse direction of the main beam and that of the side beams, respectively. Parametric studies are conducted to investigate the influence of the aspect ratio of the U-shaped structure on the modal frequencies and voltage output. It is shown that the first two horizontal modal frequencies can be tuned close to each other by shortening the side beams or extending the main beam. The ratio between the horizontal and vertical modal frequencies can also be adjusted to fit the vibration sources by altering the side beams or the main beam.
Controlling the thin interfacial buffer layer for improving the reliability of the Ta/Ta2O5/Pt resistive switching memory
Authors: Wang Yichuan , Yan Yu , Wang Chen , Chen Yuting , Li Junye , Zhao Jinshi , Hwang Cheol Seong
Published: August 2018

Thin metal interfacial layers (1-nm-thick Ti and Hf) were exploited as the appropriate interfacial layer for forming an interfacial (buffer) layer between the 10-nm-thick Ta2O5 resistance switching layer and the Ta electrode to enhance the switching cycle endurance and uniformity. The thin metal interfacial layers were in-situ oxidized to TiOx (x < 2) and HfO2 layers, respectively, during the ion beam sputter deposition on the Ta2O5 layer. Compared with the devices with no interfacial layers, the switching uniformity was improved for both interfacial layers, with Ti showing the greatest improvement. The switching cycle endurance was largely degraded for the HfO2 interfacial layer, whereas the TiOx interfacial layer greatly improved in such aspects. The appropriate level of Ti-O bond energy and an excessively high Hf-O bond energy were suggested as the main reasons for such a critical difference.
The rotating Rayleigh-Taylor instability in a strongly coupled dusty plasma
Authors: Dolai Bivash , Prajapati R. P.
Published: August 2018

The linear Rayleigh-Taylor instability (RTI) in a uniformly rotating strongly coupled dusty plasma (SCDP) is investigated both analytically and numerically. The influence of the Coriolis force on the dust particles is considered mainly owing to the drag force of the magnetized ions. The dispersion relation is analytically derived using appropriate boundary conditions and velocity profile. The dispersion characteristics are analyzed in the strongly coupled (kinetic) limit, and it is observed that the criterion of linear RTI is modified due to the presence of rotation and shear velocity comprising strong correlation effects. It is found that in the presence of intermediate magnetic field in SCDP, dust cloud rotation and strong correlation effects altogether stabilize the growth rate of linear RTI. The analytical growth rate of RTI shows a good agreement with the growth rate calculated numerically.
Topological Dirac semimetal Na3Bi films in the ultrathin limit via alternating layer molecular beam epitaxy
Authors: Pinchuk Igor V. , Asel Thaddeus J. , Franson Andrew , Zhu Tiancong , Lu Yuan-Ming , Brillson Leonard J. , Johnston-Halperin Ezekiel , Gupta Jay A. , Kawakami Roland K.
Published: August 2018

Ultrathin films of Na3Bi on insulating substrates are desired for opening a bulk bandgap and generating the quantum spin Hall effect from a topological Dirac semimetal, though continuous films in the few nanometer regime have been difficult to realize. Here, we utilize alternating layer molecular beam epitaxy to achieve uniform and continuous single-crystal films of Na3Bi(0001) on insulating Al2O3(0001) substrates and demonstrate electrical transport on films with 3.8 nm thickness (4 unit cells). The high material quality is confirmed through reflection high-energy electron diffraction, scanning tunneling microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy.
Photoionization dynamics of cis-dichloroethene from investigation of vibrationally resolved photoelectron spectra and angular distributions
Authors: Powis I. , Menzies R. C. , Holland D. M. P. , Trofimov A. B. , Skitnevskaya A. D. , Gromov E. V. , Antonsson E. , Patanen M. , Nicolas C. , Miron C.
Published: August 2018

The influence of vibronic coupling on the outer valence ionic states of cis-dichloroethene has been investigated by recording photoelectron spectra over the excitation range 19–90 eV using plane polarized synchrotron radiation, for two polarization orientations. The photoelectron anisotropy parameters and electronic state branching ratios derived from these spectra have been compared to theoretical predictions obtained with the continuum multiple scattering approach. This comparison shows that the photoionization dynamics of the Ã 2B2, B̃ 2A1, C̃ 2A2, and D̃ 2B1 states, all of which are formed through the ejection of an electron from a nominally chlorine lone-pair orbital, exhibit distinct evidence of the Cooper minimum associated with the halogen atom. While retaining a high degree of atomic character, these orbital ionizations nevertheless display clear distinctions. Simulations, assuming the validity of the Born-Oppenheimer and the Franck-Condon approximations, of the X̃ 2B1, Ã 2B2, and D̃ 2B1 state photoelectron bands have allowed some of the vibrational structure observed in the experimental spectra to be assigned. The simulations provide a very satisfactory interpretation for the X̃ 2B1 state band but appear less successful for the Ã 2B2 and D̃ 2B1 states, with irregularities appearing in both. The B̃ 2A1 and C̃ 2A2 state photoelectron bands exhibit very diffuse and erratic profiles that cannot be reproduced at this level. Photoelectron anisotropy parameters, β, have been evaluated as a function of binding energy across the studied photon energy range. There is a clear step change in the β values of the Ã 2B2 band at the onset of the perturbed peak intensities, with β evidently adopting the value of the B̃ 2A1 band β. The D̃ 2B1 band β values also display an unexpected vibrational level dependence, contradicting Franck-Condon expectations. These various behaviors are inferred to be a consequence of vibronic coupling in this system.
Wafer-scale photolithography of ultra-sensitive nanocantilever force sensors
Authors: Pan Ying , Miller Calder , Trepka Kai , Tao Ye
Published: August 2018

The detection of small forces using singly clamped cantilevers is a fundamental feature in ultrasensitive versions of scanning probe force microscopy. In these technologies, silicon-based nanomechanical devices continue to be the most widespread high-performance nanomechanical sensors for their availability, ease of fabrication, inherently low mechanical dissipation, and good control of surface-induced mechanical dissipation. Here, we develop a robust method to batch fabricate extreme-aspect-ratio (103), singly clamped scanning nanowire mechanical resonators from plain bulk silicon wafers using standard photolithography. We discuss the superior performance and additional versatility of the approach beyond what can be achieved using the established silicon on insulator technology.
Nucleus-acoustic waves: Excitation, propagation, and stability
Authors: Karmakar Pralay Kumar , Das Papari
Published: August 2018

The propagatory excitation dynamics of the collective nucleus-acoustic waves supported in a strongly coupled self-gravitating degenerate quantum dusty plasma (QDP) system, widely realizable as the constitutive matter for white dwarfs and other compact astro-objects, is semi-analytically studied. The spherically symmetric QDP is composed of strongly coupled non-degenerate heavy nuclei, weakly coupled degenerate light nuclei, and non-relativistically and ultra-relativistically degenerate lighter electrons. A standard normal spherical mode analysis is applied to derive a complex generalized dispersion relation. A numerical illustrative calculation is executed in the ultra-low frequency approximation to see the dependency of various sensible parameters on the instability evolution. It is seen that the relative nuclear charge-mass coupling parameter (β) acts as a destabilizing and stabilizing agents in the non-relativistic (NR) and ultra-relativistic (UR) limits, respectively. The ratio of the charge density of heavy-to-light nuclear species (μ) acts as a destabilizer (stabilizer) in the NR (UR) limits, to the instability. The quantum parameter (H′) interestingly acts as a stabilizing agency in both the NR-UR limits.