bluuebunny/crossref_metadata_2025 huggingface dataset:
Nomenclature in Abdominal Wall Hernias: Is It Time for Consensus?
Authors: Parker Samuel G. , Wood Christopher P. J. , Sanders David L. , Windsor Alastair C. J.
Published: May 2017

Abdominal wall reconstruction is a rapidly evolving area of surgical interest. Due to the increase in prevalence and size of ventral hernias and the high recurrence rates, the academic community has become motivated to find the best reconstruction techniques. Whilst interrogating the abdominal wall reconstruction literature, we discovered an inconsistency in hernia nomenclature that must be addressed. The terms used to describe the anatomical planes of mesh implantation ‘inlay’, ‘sublay’ and ‘underlay’ are misinterpreted throughout. We describe the misinterpretation of these terms and give evidence of where it exists in the literature. We give three critical arguments of why these misinterpretations hinder advances in abdominal wall reconstruction research. The correct definitions of the anatomical planes, and their respective terms, are described and illustrated. Clearly defined nomenclature is required as academic surgeons strive to improve abdominal wall reconstruction outcomes and lower complication rates.
Characterization of a cerebral palsy‐like model in rats: Analysis of gait pattern and of brain and spinal cord motor areas
Authors: dos Santos Adriana Souza , de Almeida Wellington , Popik Bruno , Sbardelotto Bruno Marques , Torrejais Márcia Miranda , de Souza Marcelo Alves , Centenaro Lígia Aline
Published: May 2017

In an attempt to propose an animal model that reproduces in rats the phenotype of cerebral palsy, this study evaluated the effects of maternal exposure to bacterial endotoxin associated with perinatal asphyxia and sensorimotor restriction on gait pattern, brain and spinal cord morphology. Two experimental groups were used: Control Group (CTG) − offspring of rats injected with saline during pregnancy and Cerebral Palsy Group (CPG) − offspring of rats injected with lipopolysaccharide during pregnancy, submitted to perinatal asphyxia and sensorimotor restriction for 30 days. At 29 days of age, the CPG exhibited coordination between limbs, weight‐supported dorsal steps or weight‐supported plantar steps with paw rotation. At 45 days of age, CPG exhibited plantar stepping with the paw rotated in the balance phase. An increase in the number of glial cells in the primary somatosensory cortex and dorsal striatum were observed in the CPG, but the corpus callosum thickness and cross‐sectional area of lateral ventricle were similar between studied groups. No changes were found in the number of motoneurons, glial cells and soma area of the motoneurons in the ventral horn of spinal cord. The combination of insults in the pre, peri and postnatal periods produced changes in hindlimbs gait pattern of animals similar to those observed in diplegic patients, but motor impairments were attenuated over time. Besides, the greater number of glial cells observed seems to be related to the formation of a glial scar in important sensorimotor brain areas.
Multifactorial assessment of measurement errors affecting intraoral quantitative sensory testing reliability
Authors: Moana-Filho Estephan J. , Alonso Aurelio A. , Kapos Flavia P. , Leon-Salazar Vladimir , Durand Scott H. , Hodges James S. , Nixdorf Donald R.
Published: May 2017

Background and purpose (aims)

Measurement error of intraoral quantitative sensory testing (QST) has been assessed using traditional methods for reliability, such as intraclass correlation coefficients (ICCs). Most studies reporting QST reliability focused on assessingone source of measurement error at a time, e.g., inter- or intra-examiner (test–retest) reliabilities and employed two examiners to test inter-examiner reliability. The present study used a complex design with multiple examiners with the aim of assessing the reliability of intraoral QST taking account of multiple sources of error simultaneously.

Methods

Four examiners of varied experience assessed 12 healthy participants in two visits separated by 48 h. Seven QST procedures to determine sensory thresholds were used: cold detection (CDT), warmth detection (WDT), cold pain (CPT), heat pain (HPT), mechanical detection (MDT), mechanical pain (MPT) and pressure pain (PPT). Mixed linear models were used to estimate variance components for reliability assessment; dependability coefficients were used to simulate alternative test scenarios.

Results

Most intraoral QST variability arose from differences between participants (8.8–30.5%), differences between visits within participant (4.6–52.8%), and error (13.3–28.3%). For QST procedures other than CDT and MDT, increasing the number of visits with a single examiner performing the procedures would lead to improved dependability (dependability coefficient ranges: single visit, four examiners = 0.12–0.54; four visits, single examiner = 0.27–0.68). A wide range of reliabilities for QST procedures, as measured by ICCs, was noted for inter- (0.39–0.80) and intra-examiner (0.10–0.62) variation.

Conclusion

Reliability of sensory testing can be better assessed by measuring multiple sources of error simultaneously instead of focusing on one source at a time. In experimental settings, large numbers of participants are needed to obtain accurate estimates of treatment effects based on QST measurements. This is different from clinical use, where variation between persons (the person main effect) is not a concern because clinical measurements are done on a single person.

Implications

Future studies assessing sensorytestingreliabilityinboth clinicaland experimental settings would benefit from routinely measuring multiple sources of error. The methods and results of this study can be used by clinical researchers to improve assessment of measurement error related to intraoral sensorytesting. This should lead to improved resource allocation when designing studies that use intraoral quantitative sensory testing in clinical and experimental settings.

© 2017 Scandinavian Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.
The Varieties of Self-Transcendent Experience
Authors: Yaden David Bryce , Haidt Jonathan , Hood Ralph W. , Vago David R. , Newberg Andrew B.
Published: May 2017

Various forms of self-loss have been described as aspects of mental illness (e.g., depersonalization disorder), but might self-loss also be related to mental health? In this integrative review and proposed organizational framework, we focus on self-transcendent experiences (STEs)—transient mental states marked by decreased self-salience and increased feelings of connectedness. We first identify common psychological constructs that contain a self-transcendent aspect, including mindfulness, flow, peak experiences, mystical-type experiences, and certain positive emotions (e.g., love, awe). We then propose psychological and neurobiological mechanisms that may mediate the effects of STEs based on a review of the extant literature from social psychology, clinical psychology, and affective neuroscience. We conclude with future directions for further empirical research on these experiences.
miRNA-34c-5p inhibits amphiregulin-induced ovarian cancer stemness and drug resistance via downregulation of the AREG-EGFR-ERK pathway
Authors: Tung S-L , Huang W-C , Hsu F-C , Yang Z-P , Jang T-H , Chang J-W , Chuang C-M , Lai C-R , Wang L-H
Published: May 2017

Epithelial ovarian cancer is the most lethal gynecological cancer mainly due to late diagnosis, easy spreading and rapid development of chemoresistance. Cancer stem cells are considered to be one of the main mechanisms for chemoresistance, as well as metastasis and recurrent disease. To explore the stemness characteristics of ovarian cancer stem cells, we successfully enriched ovarian cancer stem-like cells from an established ovarian cancer cell line (SKOV-I6) and a fresh ovarian tumor-derived cell line (OVS1). These ovarian cancer stem-like cells possess important cancer stemness characteristics including sphere-forming and self-renewing abilities, expressing important ovarian cancer stem cell and epithelial–mesenchymal transition markers, as well as increased drug resistance and potent tumorigenicity. Microarray analysis of OVS1-derived sphere cells revealed increased expression of amphiregulin (AREG) and decreased expression of its conserved regulatory microRNA, miR-34c-5p, when compared with the OVS1 parental cells. Overexpression of AREG and decreased miR-34c-5p expression in SKOV-I6 and OVS1 sphere cells were confirmed by quantitative real-time PCR analysis. Luciferase reporter assay and mutant analysis confirmed that AREG is a direct target of miR-34c-5p. Furthermore, AREG-mediated increase of sphere formation, drug resistance toward docetaxel and carboplatin, as well as tumorigenicity of SKOV-I6 and OVS1 cells could be abrogated by miR-34c-5p. We further demonstrated that miR-34c-5p inhibited ovarian cancer stemness through downregulation of the AREG-EGFR-ERK pathway. Overexpression of AREG was found to be correlated with advanced ovarian cancer stages and poor prognosis. Taken together, our data suggest that AREG promotes ovarian cancer stemness and drug resistance via the AREG-EGFR-ERK pathway and this is inhibited by miR-34c-5p. Targeting AREG, miR-34c-5p could be a potential strategy for anti-cancer-stem cell therapy in ovarian cancer.
Diglycolamic acid-functionalized multiwalled carbon nanotubes as a highly efficient sorbent for f-block elements: experimental and theoretical investigations
Authors: Sengupta Arijit , Kumar Singha Deb Ashish , Dasgupta Kinshuk , Adya V. C. , Ali Sk. Musharaf
Published: May 2017

Diglycolamic acid-functionalized carbon nanotubes were employed for the efficient and selective separation of Pu4+, PuO22+and Am3+.
Calcination temperature as a probe to tune the non-enzymatic glucose sensing activity of Cu–Ni bimetallic nanocomposites
Authors: Chawla Mohit , Randhawa Jaspreet Kaur , Siril Prem Felix
Published: May 2017

A seven-fold increase in the glucose sensing activity of CuO–NiO bimetallic nanocomposites was inducedviacalcination.
A magnetic restricted access material for rapid solid phase extraction of multiple macrolide antibiotics in honey
Authors: Liu Lijun , Yang Bingcheng , Zhang Feifang , Liang Xinmiao
Published: May 2017

A magnetic restricted access material (MRAM) sorbent has been synthesized and for the first time used for the extraction of macrolide antibiotics (MACs).
Organocatalyzed coupling of carbon dioxide with epoxides for the synthesis of cyclic carbonates: catalyst design and mechanistic studies
Authors: Alves M. , Grignard B. , Mereau R. , Jerome C. , Tassaing T. , Detrembleur C.
Published: May 2017

The coupling of carbon dioxide (CO2) with epoxides with the formation of cyclic carbonates is a highly attractive 100% atom economic reaction. It represents a greener and safer alternative to the conventional synthesis of cyclic carbonates from diols and toxic phosgene.
Wide spectrum responsive CdS/NiTiO3/CoS with superior photocatalytic performance for hydrogen evolution
Authors: Wang Zhaoyu , Peng Junwen , Feng Xue , Ding Zhengxin , Li Zhaohui
Published: May 2017

Wide spectrum responsive CdS/NiTiO3/CoS with superior photocatalytic performance for H2 evolution.
Amphiphilic coatings for the protection of upconverting nanoparticles against dissolution in aqueous media
Authors: Plohl Olivija , Kralj Slavko , Majaron Boris , Fröhlich Eleonore , Ponikvar-Svet Maja , Makovec Darko , Lisjak Darja
Published: May 2017

Dissolution of upconverting nanoparticles (β-NaYF4:Yb3+,Tm3+) in PBS was efficiently suppressed by a polymer coating, PMAO cross-linked with BHMT.
A tetragonal polymorph of SrMn2P2made under high pressure – theory and experiment in harmony
Authors: Xie Weiwei , Winiarski Michał J. , Klimczuk Tomasz , Cava R. J.
Published: May 2017

A trigonal–tetragonal phase transition in SrMn2P2is proposed and confirmed experimentally under high pressure. At ambient pressure, SrMn2P2crystallizes in the primitive trigonal La2O3structure type (space groupP3̄m1) in blue. Under high pressure, the tetragonal ThCr2Si2structure type (space groupI4/mmm) in red is more stable.
Heteroleptic iron(iii) Schiff base spin crossover complexes: halogen substitution, solvent loss and crystallite size effects
Authors: Phonsri Wasinee , Macedo David S. , Davies Casey G. , Jameson Guy N. L. , Moubaraki Boujemaa , Murray Keith S.
Published: May 2017

New heteroleptic iron(iii) spin crossover complexes, [Fe(qsal-X)(thsa)]·nMeCN, have been investigated. Halogen substitution, solvent and crystallite size effects are discussed.
Temperature-induced reversible single-crystal-to-single-crystal isomerisation of uranyl polyrotaxanes: an exquisite case of coordination variability of the uranyl center
Authors: Xie Zhen-ni , Mei Lei , Wu Qun-yan , Hu Kong-qiu , Xia Liang-shu , Chai Zhi-fang , Shi Wei-qun
Published: May 2017

A reversible solid-state isomerisation mediated by the change of uranyl-ligand coordination modes has been achieved in uranyl polyrotaxanes by a temperature-induced strategy.
Fluorinated cyclometalated iridium(iii) complexes as mitochondria-targeted theranostic anticancer agents
Authors: Ouyang Miao , Zeng Leli , Huang Huaiyi , Jin Chengzhi , Liu Jiangping , Chen Yu , Ji Liangnian , Chao Hui
Published: May 2017

Cyclometalated iridium(iii) complexes bearing different numbers of fluorine atoms were developed to induce apoptosis via mitochondrial pathways and demonstrated much better anticancer activities than the widely used clinical chemotherapeutic agent cisplatin.
Advancing polyethylene properties by incorporating NO2 moiety in 1,2-bis(arylimino)acenaphthylnickel precatalysts: synthesis, characterization and ethylene polymerization
Authors: Mahmood Qaiser , Zeng Yanning , Wang Xinxin , Sun Yang , Sun Wen-Hua
Published: May 2017

A family of 1-(2,6-dibenzhydryl-4-nitrophenylimino)-2-aryliminoacenaphthylnickel halides, on activation with either Et2AlCl or EASC, produced ultra-high-molecular-weight highly branched polyethylenes.
A thioglycerol route to bio-based bis-cyclic carbonates: poly(hydroxyurethane) preparation and post-functionalization
Authors: Lamarzelle Océane , Hibert Geoffrey , Lecommandoux Sébastien , Grau Etienne , Cramail Henri
Published: May 2017

The present work is dedicated to the design of novel sulfur-substituted cyclic carbonates from thioglycerol, fatty acids and sugar derivatives.
Does Kinematic Alignment Improve Short-Term Functional Outcomes after Total Knee Arthroplasty Compared with Mechanical Alignment? A Systematic Review and Meta-analysis
Authors: Li Yanhong , Wang Yuliang , Yang Mingxuan , Wang Shuanke
Published: May 2017

This meta-analysis was conducted to study whether kinematically aligned total knee arthroplasty (TKA) improves short-term functional outcomes compared with mechanical alignment without changing the hip–knee–ankle angle. Prospective cohort studies were searched from electronic literature databases, including PubMed, Web of Science, Embase (Ovid interface), and Cochrane Library (Ovid interface). Total 1,159 records were identified. Six trials involving 561 patients were eligible for data extraction and meta-analysis. The included studies recorded outcomes in the follow-up range from 6 to 34 months. Primary outcomes were to assess the functional outcomes in follow-up, and KA group achieved better performance on WOMAC score (mean difference [MD] = −18.82, 95% CI: −16.06 to −5.58), knee function score (MD = 7.23, 95% CI: 0.52–13.94), Oxford knee score (MD = 4.76, 95% CI: 0.40–9.12), and knee range of flexion (MD = 4.48, 95% CI: 2.09–6.86), whereas other parameters including Knee Society score, knee range of extension, VAS pain score, and the occurrence of the complications were without significant difference (p > 0.05). Second outcomes evaluated the perioperative clinic indexes. Our meta-analysis showed that KA group had a shorter time of operation (MD = −15.44, 95% CI: −27.47 to −3.71) and a longer walk distance before discharge (MD = 53.24, 95% CI: 21.32–85.15) when compared with the MA group, whereas the change in hemoglobin, incision length, knee range of flexion before discharge, and length of stays were without significant difference (p > 0.05). Third outcomes were used to analyze the alignment data. Our study showed that KA had larger angles of femoral component and mechanical axis of the femur (MD = −1.95,95% CI: −2.77 to −1.13), tibial component and mechanical axis of tibia (MD = 2.06, 95% CI: 1.43–2.70), anatomic knee angle (MD = −0.72, 95% CI: −1.33 to −0.11), and operative limb alignment (MD = −1.97, 95% CI: −2.50 to −1.45,) compared with the MA group, but the hip–knee–ankle angles between the two groups were similar. KA provided better functional outcomes and better flexion following short-term follow-up of TKA. However, longer-term follow-up and larger sample studies are needed to put into research in the future.
Inter- and Intraobserver Reliabilities of Four Different Radiographic Grading Scales of Osteoarthritis of the Knee Joint
Authors: Köse Özkan , Acar Baver , Çay Fatif , Güler Ferhat , Yüksel Halil , Yilmaz Baris
Published: May 2017

The purpose of this study was to investigate the interobserver and intraobserver reliabilities of four different radiographic grading scale of osteoarthritis (OA) of the knee joint, namely, Kellgren–Lawrence (KL), Ahlback, Brandt, and OA Research Society International (OARSI). One consultant orthopaedic surgeon and one rheumatologist who were familiar with these OA grading scales participated in the study. Radiological assessments were performed in random order by each observer on two separate occasions, at least 2 weeks apart. K-statistics were used to establish a relative level of agreement between the observers for the two readings and between separate readings by the same observer. A total of 140 patients (53 males and 87 females) with a mean age of 61.2 years (range, 50–72 years) were included in the study. Intraobserver reliability for KL was substantial for observer A (κ: 0.753) and moderate for observer B (κ: 0.573). Interobserver reliability for KL was moderate for both observers (κ: 0.499 and 0.458, respectively). Intraobserver reliability for Ahlback was substantial for observer A (κ: 0.768) and moderate for observer B (κ: 0.561). Interobserver reliability for Ahlback was fair for both observers (κ: 0.365 and 0.204, respectively). Intraobserver reliability for Brandt was substantial for observer A (κ: 0.741) and moderate (κ: 0.425) for observer B. Interobserver reliability for Brandt was fair for both observers (κ: 0.308 and κ: 0.246, respectively). Intraobserver reliability for OARSI was substantial for observer A (κ: 0.792) and moderate for observer B (κ: 0.508). Interobserver reliability for OARSI was moderate for observer A (κ: 0.425) and slight for observer B (κ: 0.175). None of the studied OA grading scales showed acceptable reliability (κ > 0.80). The evaluation of patients with OA should not be dependent on radiographic findings alone; clinical findings should also guide the treatment and follow-up.
The dynamics of charge transfer with and without a barrier: A very simplified model of cyclic voltammetry
Authors: Ouyang Wenjun , Subotnik Joseph E.
Published: May 2017

Using the Anderson-Holstein model, we investigate charge transfer dynamics between a molecule and a metal surface for two extreme cases. (i) With a large barrier, we show that the dynamics follow a single exponential decay as expected; (ii) without any barrier, we show that the dynamics are more complicated. On the one hand, if the metal-molecule coupling is small, single exponential dynamics persist. On the other hand, when the coupling between the metal and the molecule is large, the dynamics follow a biexponential decay. We analyze the dynamics using the Smoluchowski equation, develop a simple model, and explore the consequences of biexponential dynamics for a hypothetical cyclic voltammetry experiment.
Development of PZT-excited stroboscopic shearography for full-field nondestructive evaluation
Authors: Asemani Hamidreza , Park Jinwoo , Lee Jung-Ryul , Soltani Nasser
Published: May 2017

Nondestructive evaluation using shearography requires a way to stress the inspection target. This technique is able to directly measure the displacement gradient distribution on the object surface. Shearography visualizes the internal structural damages as the anomalous pattern in the shearograpic fringe pattern. A piezoelectric (PZT) excitation system is able to generate loadings in the vibrational, acoustic, and ultrasonic regimes. In this paper, we propose a PZT-excited stroboscopic shearography. The PZT excitation could generate vibrational loading, a stationary wavefield, and a nonstationary propagation wave to fulfill the external loading requirement of shearography. The sweeping of the PZT excitation frequency, the formation of a standing wave, and a small shearing to suppress the incident wave were powerful controllable tools to detect the defects. The sweeping of the PZT excitation frequency enabled us to determine one of the defect-sensitive frequencies almost in real time. In addition, because the defect sensitive frequencies always existed in wide and plural ranges, the risk of the defect being overlooked by the inspector could be alleviated. The results of evaluation using stroboscopic shearography showed that an artificial 20 mm-diameter defect could be visualized at the excitation frequencies of 5–8 kHz range and 12.5–15.5 kHz range. This technique provided full field reliable and repeatable inspection results. Additionally, the proposed method overcame the important drawback of the time-averaged shearography, being required to identify the resonance vibration frequency sensitive to the defect.
An experimental setup to study delayed electron emission upon photoexcitation of trapped polyatomic anions
Authors: Saha K. , Prabhakaran A. , Chandrasekaran V. , Rappaport M. L. , Heber O. , Zajfman D.
Published: May 2017

A Velocity Map Imaging (VMI) spectrometer has been designed and integrated with an electrostatic ion beam trap to study delayed electron emission from trapped polyatomic anions upon photodetachment. The VMI spectrometer is small in size and can record a wide range of photoelectron energies, with variable magnification. Delayed electron emission can be recorded in our experimental setup for any time duration after the photoexcitation of the polyatomic anions. Experiments were carried out with trapped O− and C5− ions to demonstrate the capability of the spectrometer. Delayed electron emissions from C5− as well as prompt photoelectrons from O− were detected by the VMI spectrometer upon photoexcitation. The design and performance of the spectrometer are presented in detail.
Imaging at an x-ray absorption edge using free electron laser pulses for interface dynamics in high energy density systems
Authors: Beckwith M. A. , Jiang S. , Schropp A. , Fernandez-Pañella A. , Rinderknecht H. G. , Wilks S. C. , Fournier K. B. , Galtier E. C. , Xing Z. , Granados E. , Gamboa E. , Glenzer S. H. , Heimann P. , Zastrau U. , Cho B. I. , Eggert J. H. , Collins G. W. , Ping Y.
Published: May 2017

Tuning the energy of an x-ray probe to an absorption line or edge can provide material-specific measurements that are particularly useful for interfaces. Simulated hard x-ray images above the Fe K-edge are presented to examine ion diffusion across an interface between Fe2O3 and SiO2 aerogel foam materials. The simulations demonstrate the feasibility of such a technique for measurements of density scale lengths near the interface with submicron spatial resolution. A proof-of-principle experiment is designed and performed at the Linac coherent light source facility. Preliminary data show the change of the interface after shock compression and heating with simultaneous fluorescence spectra for temperature determination. The results provide the first demonstration of using x-ray imaging at an absorption edge as a diagnostic to detect ultrafast phenomena for interface physics in high-energy-density systems.
On the influence of additive and multiplicative noise on holes in dissipative systems
Authors: Descalzi Orazio , Cartes Carlos , Brand Helmut R.
Published: May 2017

We investigate the influence of noise on deterministically stable holes in the cubic-quintic complex Ginzburg-Landau equation. Inspired by experimental possibilities, we specifically study two types of noise: additive noise delta-correlated in space and spatially homogeneous multiplicative noise on the formation of π-holes and 2π-holes. Our results include the following main features. For large enough additive noise, we always find a transition to the noisy version of the spatially homogeneous finite amplitude solution, while for sufficiently large multiplicative noise, a collapse occurs to the zero amplitude solution. The latter type of behavior, while unexpected deterministically, can be traced back to a characteristic feature of multiplicative noise; the zero solution acts as the analogue of an absorbing boundary: once trapped at zero, the system cannot escape. For 2π-holes, which exist deterministically over a fairly small range of values of subcriticality, one can induce a transition to a π-hole (for additive noise) or to a noise-sustained pulse (for multiplicative noise). This observation opens the possibility of noise-induced switching back and forth from and to 2π-holes.
Perspective: Chemical reactions in ionic liquids monitored through the gas
(vacuum)/liquid interface
Authors: Maier F. , Niedermaier I. , Steinrück H.-P.
Published: May 2017

This perspective analyzes the potential of X-ray photoelectron spectroscopy under ultrahigh vacuum (UHV) conditions to follow chemical reactions in ionic liquids in situ. Traditionally, only reactions occurring on solid surfaces were investigated by X-ray photoelectron spectroscopy (XPS) in situ. This was due to the high vapor pressures of common liquids or solvents, which are not compatible with the required UHV conditions. It was only recently realized that the situation is very different when studying reactions in Ionic Liquids (ILs), which have an inherently low vapor pressure, and first studies have been performed within the last years. Compared to classical spectroscopy techniques used to monitor chemical reactions, the advantage of XPS is that through the analysis of their core levels all relevant elements can be quantified and their chemical state can be analyzed under well-defined (ultraclean) conditions. In this perspective, we cover six very different reactions which occur in the IL, with the IL, or at an IL/support interface, demonstrating the outstanding potential of in situ XPS to gain insights into liquid phase reactions in the near-surface region.
Note: Using a Kösters prism to create a fringe pattern
Authors: Capellmann R. F. , Bewerunge J. , Platten F. , Egelhaaf S. U.
Published: May 2017

The interference of two crossed laser beams results in a standing wave. Such fringe patterns are exploited in different instruments such as interferometers or laser-Doppler anemometers. We create a fringe pattern in the sample plane of a microscope using a compact apparatus based on a Kösters prism. The fringe pattern is shown to be spatially and temporally very stable, covers a large area, and its spacing is easily tunable. In addition, we exploit it to impose a sinusoidal potential on colloidal particles.
Spur-line based magnetically tunable bandstop filter using partially magnetized ferrite thin films
Authors: Sharma Deepanshu , Khare Neeraj , Koul Shiban K. , Abegaonkar Mahesh P.
Published: May 2017

In this letter, a compact spur-line based magnetically tunable bandstop filter in the flip-chip configuration using partially magnetized ferrite thin films is reported. The spur-line bandstop filter is designed to operate at a centre frequency of ∼12.75 GHz and is fabricated on a quartz substrate. Magnetic thin films of cobalt ferrite, cobalt-nickel ferrite, and nickel ferrite are used, which show tunabilities of 5.1%, 6.0%, and 7.5%, respectively, after applying the bias magnetic field ranging from 0 to 300 Oe. The difference in the tunability is attributed to the change in the permeability values of the magnetic thin films after applying the bias magnetic field. The shift in the centre frequency is confirmed by the simulations carried out using CST microwave studio software. This work demonstrates the opportunities to use the partially magnetized ferrite thin films in the presence of a low bias magnetic field for achieving higher tunability in a microwave bandstop filter.
Dielectric geometric phase optical elements fabricated by femtosecond direct laser writing in photoresists
Authors: Wang Xuewen , Kuchmizhak Aleksandr A. , Brasselet Etienne , Juodkazis Saulius
Published: May 2017

We propose to use a femtosecond direct laser writing technique to realize dielectric optical elements from photo-resist materials for the generation of structured light from purely geometrical phase transformations. This is illustrated by the fabrication and characterization of spin-to-orbital optical angular momentum couplers generating optical vortices of topological charge from 1 to 20. In addition, the technique is scalable and allows obtaining microscopic to macroscopic flat optics. These results thus demonstrate that direct 3D photopolymerization technology qualifies for the realization of spin-controlled geometric phase optical elements.
Large thermoelectric power factor at low temperatures in one-dimensional telluride Ta4SiTe4
Authors: Inohara Takumi , Okamoto Yoshihiko , Yamakawa Youichi , Yamakage Ai , Takenaka Koshi
Published: May 2017

We report the discovery of a very large thermoelectric power over –400 μV K−1 in the whisker crystals of a one-dimensional telluride Ta4SiTe4, while maintaining a low electrical resistivity of ρ = 2 mΩ cm, yielding a very large power factor of P = 80 μW cm−1 K−2 at an optimum temperature of 130 K. This temperature is widely controlled from the cryogenic temperature of 50 K to room temperature by chemical doping, resulting in the largest P of 170 μW cm−1 K−2 at 220–280 K. These P values far exceed those of the Bi2Te3-Sb2Te3 alloys at around room temperature, offering an avenue for realizing the practical-level thermoelectric cooling at low temperatures. The coexistence of a one-dimensional electronic structure and a very small band gap appearing in the vicinity of the Dirac semimetals probably causes the very large power factors in Ta4SiTe4, indicating that the “one-dimensional Dirac semimetal” is a promising way to find high-performance thermoelectric materials for the low temperature applications.
Optical evidence for blue shift in topological insulator bismuth selenide in the few-layer limit
Authors: Sapkota Yub Raj , Alkabsh Asma , Walber Aaron , Samassekou Hassana , Mazumdar Dipanjan
Published: May 2017

Optical bandgap properties of high-quality few-layer topological insulator Bi2Se3 thin films are investigated using broadband absorption spectroscopy. We provide direct optical evidence for blue shift in the bulk bandgap of Bi2Se3 as it approaches the two-dimensional limit. The blue shift is robust and observed in both protected (capped) and exposed (uncapped) thin films. The behavior is strongest below six quintuple layers (QLs), particularly at the 2 and 3 QL level, where finite-size effects are known to be most significant in Bi2Se3. A further bandgap increase is observed in all films that we attribute to the Burstein-Moss effect. Our result provides additional insights into the scaling behavior of topological materials. The bandgap increase has a significant impact on the electronic and optoelectronic applications of topological insulators.
Phase inversion of slug flow on step surface to form high viscosity droplets in microchannel
Authors: Man Jia , Li Zhongnan , Li Jiang , Chen Haosheng
Published: May 2017

Slug flow is a typical two phase flow in which droplets are lubricated by an immiscible continuous phase in a microchannel. The step surface is found to break the lubrication film and induce a phase inversion of the slug flow. The reduction in the film thickness by the step is quantitatively calculated and measured, and the critical droplet length for the breakup of the film is also revealed. This step-induced phase inversion is demonstrated to form high-in-low-viscosity emulsion droplets from a low-in-high-viscosity slug flow.
Electrically tunable and broader-band sound absorption by using micro-perforated dielectric elastomer actuator
Authors: Lu Zhenbo , Shrestha Milan , Lau Gih-Keong
Published: May 2017

Most membrane-type acoustic absorbers for low-frequency sound attenuation are applicable only at a fixed resonant frequency for a narrow bandwidth. Tuning of the acoustic absorption spectrum is desired to match the varying noises. This letter presents a micro-perforated dielectric elastomer actuator (MPDEA) to make a broader-band acoustic absorber electrically tunable. Voltage activation of the MPDEA reduces the membrane tension and hole size and thus enables the active shifting of the acoustic absorption spectrum. Such a membrane tuning method does not require discrete mechanical parts as for the cavity tuning method. Also presented are the analytical models to predict the voltage-induced hole size change and acoustic characteristics of MPDEA.
Ultraviolet light-absorbing and emitting diodes consisting of a p-type transparent-semiconducting NiO film deposited on an n-type GaN homoepitaxial layer
Authors: Nakai Hiroshi , Sugiyama Mutsumi , Chichibu Shigefusa F.
Published: May 2017

Gallium nitride (GaN) and related (Al,Ga,In)N alloys provide practical benefits in the production of light-emitting diodes (LEDs) and laser diodes operating in ultraviolet (UV) to green wavelength regions. However, obtaining low resistivity p-type AlN or AlGaN of large bandgap energies (Eg) is a critical issue in fabricating UV and deep UV-LEDs. NiO is a promising candidate for useful p-type transparent-semiconducting films because its Eg is 4.0 eV and it can be doped into p-type conductivity of sufficiently low resistivity. By using these technologies, heterogeneous junction diodes consisting of a p-type transparent-semiconducting polycrystalline NiO film on an n-type single crystalline GaN epilayer on a low threading-dislocation density, free-standing GaN substrate were fabricated. The NiO film was deposited by using the conventional RF-sputtering method, and the GaN homoepitaxial layer was grown by metalorganic vapor phase epitaxy. They exhibited a significant photovoltaic effect under UV light and also exhibited an electroluminescence peak at 3.26 eV under forward-biased conditions. From the conduction and valence band (EV) discontinuities, the NiO/GaN heterointerface is assigned to form a staggered-type (TYPE-II) band alignment with the EV of NiO higher by 2.0 eV than that of GaN. A rectifying property that is consistent with the proposed band diagram was observed in the current-voltage characteristics. These results indicate that polycrystalline NiO functions as a hole-extracting and injecting layer of UV optoelectronic devices.
Tuning electrical conductivity, charge transport, and ferroelectricity in epitaxial BaTiO3 films by Nb-doping
Authors: Jing Xiaosai , Xu Wenchao , Yang Cheng , Feng Jiajun , Zhang Aihua , Zeng Yanping , Qin Minghui , Zeng Min , Fan Zhen , Gao Jinwei , Gao Xingsen , Zhou Guofu , Lu Xubing , Liu J.-M.
Published: May 2017

The electrical conductivity, charge transport behavior, and ferroelectricity of epitaxial BaNbxTi1-xO3 films (BNTO, 0.0 ≤ x ≤ 0.5) prepared by pulsed laser deposition are investigated. It is found that Nb-doping can tune the conventional insulating BaTiO3 films from an insulating to highly conductive semiconducting or metallic state, resulting in a variation of the electrical conductivity of the BNTO films over 105. For x ≤ 0.25, the charge transport is dominated by the small polaron hopping mechanism, while the charge transport for x = 0.5 transits from the bipolaron to the small-polaron, and then the thermal phonon scattering mechanisms with increasing temperature. Interestingly, the piezo-force microscopy imaging reveals the presence of ferroelectricity in the properly Nb-doped conductive BNTO films (x ≤ 0.25) deposited in the presence of a small amount of oxygen (3 × 10−3 Pa). Our work provides additional technical roadmaps to manipulate the conductivity and charge transport behaviors in ferroelectric films, which will boost potential applications in future information storage, sensors, and photovoltaic devices.
Visco-resistive length scale in flux pile-up and series solutions for magnetic reconnection
Authors: McMahon Liam C.
Published: May 2017

Current sheets play a crucial role in determining the physics of magnetic reconnection in solar flares. We investigate the structure of a reconnecting visco-resistive (VR) current sheet in two dimensional steady incompressible MHD. We review a number of solutions that demonstrate that several distinct potential length scalings may emerge for VR reconnection. We find a criterion for the presence of a VR length scale in magnetic flux pile-up solutions and we utilise a series expansion technique in order to describe the inner solution of a VR current sheet. We posit that a VR length scale is the fundamental length scale of a VR current sheet and its absence is purely a feature of a limited class of particular solutions for the inflow velocity profile.
Single electron dynamics in a Hall thruster electromagnetic field profile
Authors: Marini Samuel , Pakter Renato
Published: May 2017

In this work, the single electron dynamics in a simplified three dimensional Hall thruster model is studied. Using Hamiltonian formalism and the concept of limiting curves, one is able to determine confinement conditions for the electron in the acceleration channel. It is shown that as a given parameter of the electromagnetic field is changed, the particle trajectory may transit from regular to chaotic without affecting the confinement, which allows one to make a detailed analysis of the role played by the chaos. The ionization volume is also computed, which measures the probability of an electron to ionize background gas atoms. It is found that there is a great correlation between chaos and increased effective ionization volume. This indicates that a complex dynamical behavior may improve the device efficiency by augmenting the ionization capability of each electron, requiring an overall lower electron current.
Tunable prism based on piezoelectric metamaterial for acoustic beam steering
Authors: Xu J. , Tang J.
Published: May 2017

This letter reports a tunable acoustic prism featuring continuous beam steering for transverse waves at a single frequency. The proposed prism is comprised of arrayed piezoelectric unit-cells with individually connected inductive shunt circuits. Taking advantage of wave velocity shifting in the vicinity of the local resonant frequency of unit-cells, we can steer the harmonic transverse wave by adjusting the inductive loads, i.e., tuning the inductances. This beam steering mechanism is facilitated by add-on piezoelectric circuitry through electro-mechanical coupling, whereas the host medium is not altered. Our analysis shows that the propagation direction of an acoustic wave has a tuning range of more than 30°. This tunable prism can be used as an acoustic metamaterial for various devices operating at broadband frequencies.
Microwave metamaterials made by fused deposition 3D printing of a highly conductive copper-based filament
Authors: Xie Yangbo , Ye Shengrong , Reyes Christopher , Sithikong Pariya , Popa Bogdan-Ioan , Wiley Benjamin J. , Cummer Steven A.
Published: May 2017

This work reports a method for fabricating three-dimensional microwave metamaterials by fused deposition modeling 3D printing of a highly conductive polymer composite filament. The conductivity of such a filament is shown to be nearly equivalent to that of a perfect conductor for microwave metamaterial applications. The expanded degrees-of-freedom made available by 3D metamaterial designs are demonstrated by designing, fabricating, and testing a 3D-printed unit cell with a broadband permittivity as high as 14.4. The measured and simulated S-parameters agree well with a mean squared error smaller than 0.1. The presented method not only allows reliable and convenient fabrication of microwave metamaterials with high conductivity but also opens the door to exploiting the third dimension of the unit cell design space to achieve enhanced electromagnetic properties.
Photonic band-gap and defect modes of a one-dimensional photonic crystal under localized compression
Authors: Sánchez A. , Porta A. V. , Orozco S.
Published: May 2017

The rupture of periodicity caused by one defect (defect layer) in a one-dimensional photonic crystal (1DPhC) results in a narrow transmission spectral line in the photonic band-gap, and the field distribution shows a strong confinement in the proximity of the defect layer. In this work, we present a theoretical model to calculate the frequency of defect modes caused by defect layers induced by localized mechanical stress. Two periodical arrangements were studied: one with layers of poly(methyl-methacrylate) (PMMA) and polystyrene (PS), PMMA-PS; the other with layers of PMMA and fused silica (SiO2), PMMA-SiO2. The defect layers were induced by localized compression (tension). The frequencies of the defect modes were calculated using elasto-optical theory and plane wave expansion and perturbation methods. Numerical results show that the frequency of the defect mode increases (decreases) when the compression (tension) increases. Based on the theoretical model developed, we show that compression of n layers of a 1DPhC induces n defect modes whose frequencies depend on the compression magnitude in the case of normal incidence of electromagnetic waves, in accordance with the results reported for other types of defect layers. The methodology shows the feasibility of the plane wave expansion and perturbation methods to study the frequency of the defect modes. Both periodical arrangements are suitable for designing mechanically tunable (1DPhC)-based narrow pass band filters and narrow reflectors in the (60, 65) THz range.
Self-reconstruction of the degree of coherence of a partially coherent vortex beam obstructed by an opaque obstacle
Authors: Liu Xianlong , Peng Xiaofeng , Liu Lin , Wu Gaofeng , Zhao Chengliang , Wang Fei , Cai Yangjian
Published: May 2017

The distribution of degree of coherence of a partially coherent vortex beam reveals rich information about the vortex phase, and it is known that one can determine the topological charge (or orbital angular moment) of a partially coherent vortex beam from its degree of coherence distribution in the focal plane (or in the far field). In this letter, we demonstrate both numerically and experimentally that the degree of coherence distribution of a partially coherent vortex beam that is blocked by an opaque obstacle can self-reconstruct in the focal plane. Thus, one still can determine the topological charge of an obstructed partially coherent vortex beam from its degree of coherence distribution in the focal plane. Our results can find application in information transmission and recovery.
TixSb100−x thin films as candidates for phase-change memory application
Authors: Wu Weihua , Chen Shiyu , Zhai Jiwei , Liu Xinyi , Lai Tianshu , Song Sannian , Song Zhitang
Published: May 2017

Tellurium-free TixSb100−x phase-change materials were systematically investigated. The amorphous-to-crystalline transition was studied by in situ resistance measurements. The crystallization temperature, crystalline resistance, and optical bandgap of TixSb100−x thin films were enhanced significantly with the increase in the titanium concentration. The phase structure and microstructure were confirmed by X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM), respectively. The chemical state of the elements was detected by X-ray photoelectron spectroscopy (XPS). The phase transition speed between the amorphous and crystalline states was obtained by picosecond laser pulses. Phase change memory cells based on the Ti27Sb73 thin film were fabricated to evaluate the electrical characteristics as well. The results indicate that the TixSb100−x thin films have the great potentiality in phase change memory applications.
Controllable Si (100) micro/nanostructures by chemical-etching-assisted femtosecond laser single-pulse irradiation
Authors: Li Xiaowei , Xie Qian , Jiang Lan , Han Weina , Wang Qingsong , Wang Andong , Hu Jie , Lu Yongfeng
Published: May 2017

In this study, silicon micro/nanostructures of controlled size and shape are fabricated by chemical-etching-assisted femtosecond laser single-pulse irradiation, which is a flexible, high-throughput method. The pulse fluence is altered to create various laser printing patterns for the etching mask, resulting in the sequential evolution of three distinct surface micro/nanostructures, namely, ring-like microstructures, flat-top pillar microstructures, and spike nanostructures. The characterized diameter of micro/nanostructures reveals that they can be flexibly tuned from the micrometer (∼2 μm) to nanometer (∼313 nm) scales by varying the laser pulse fluence in a wide range. Micro-Raman spectroscopy and transmission electron microscopy are utilized to demonstrate that the phase state changes from single-crystalline silicon (c-Si) to amorphous silicon (a-Si) after single-pulse femtosecond laser irradiation. This amorphous layer with a lower etching rate then acts as a mask in the wet etching process. Meanwhile, the on-the-fly punching technique enables the efficient fabrication of large-area patterned surfaces on the centimeter scale. This study presents a highly efficient method of controllably manufacturing silicon micro/nanostructures with different single-pulse patterns, which has promising applications in the photonic, solar cell, and sensors fields.
Band alignment of lateral two-dimensional heterostructures with a transverse dipole
Authors: Leenaerts O. , Vercauteren S. , Partoens B.
Published: May 2017

It was recently shown that the electronic band alignment in lateral two-dimensional heterostructures is strongly dependent on the system geometry, such as heterostructure width and layer thickness. This is so even in the absence of polar edge terminations because of the appearance of an interface dipole between the two different materials. In this study, this work is expanded to include two-dimensional materials that possess an electronic dipole over their surface, i.e., in the direction transverse to the crystal plane. To this end, a heterostucture consisting of polar hydrofluorinated graphene and non-polar graphane layers is studied with first-principles calculations. As for non-polar heterostructures, a significant geometry dependence is observed with two different limits for the band offset. For infinitely wide heterostructures, the potential step in the vacuum is equally divided over the two sides of the heterostructure, resulting in a finite potential step in the heterostructure. For infinitely thick heterostructure slabs, on the other hand, the band offset is reduced, similar to the three-dimensional case.