bluuebunny/crossref_metadata_2025 huggingface dataset:
A new speech enhancement algorithm for millimeter‐wave radar speech sensor
Authors: Jiao Mingke , Lou Lin , Hu Jie , Geng Xiliang , Zhang Wenyuan , Zhang Peng , Wang Jianqi
Published: March 2014

A novel millimeter‐wave radar speech sensor based on vibration detection developed in our laboratory can penetrate nonmetal barriers to obtain speech signals, which expands traditional speech detection techniques. However, the radar speech signals are usually corrupted by nonuniform noises that include radar noise, electrocircuit noise, and so on. The article, therefore, proposed an improved Wiener filter method based on wavelet entropy (WE) to suppress the nonuniform noise. The utilization of WE contributes to the high efficiency of the algorithm for suppressing nonuniform radar noise. WE point detection can provide a basis through which radar noise can be accurately estimated and updated in an adaptive manner, resulting in accurate a priori signal‐to‐noise ratios obtained from updated noise estimations and reduction of nonuniform noise. The results from spectrogram and mean opinion score demonstrate that the radar nonuniform noise can be reduced efficiently, and the radar speech quality was improved effectively. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1184–1189, 2014
Miniature dual‐mode dual‐band bandpass filter with improved passbands performance for 2.4/5.2 GHz WLAN application
Authors: Wu Yan‐liang , Liao Cheng , Xiong Xiang‐zheng , Zhou Hai‐jing
Published: March 2014

In this article, a miniature dual‐mode dual‐band bandpass filter (BPF) based on novel complementary center‐stub‐loaded stepped‐impedance resonators has been presented. By loading an open stub at the center of stepped‐impedance resonator, the center frequency of the fundamental even‐mode could be independently controlled, whereas that of the fundamental odd‐mode is fixed. A dual‐mode dual‐band BPF using complementary configuration is implemented with three transmission zeros. To validate the design and analysis, a prototype filter has been designed and fabricated with its two bands located at 2.4/5.2 GHz for WLAN. The measured performances show good agreements with those of the coupling matrix analysis and electromagnetic simulation. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1235–1238, 2014
A facile route for the synthesis of nanotubular composite of polyaniline with cobalt and its superparamagnetism below blocking temperature
Authors: Gupta K. , Das P. T. , Nath T. K. , Meikap A. K. , Jana P. C.
Published: March 2014

We have prepared nanotubular composite of polyaniline with cobalt from the reverse micelle of sodium dioctyl sulfosuccinate and n‐hexane. Samples are characterized with characterized by X‐ray diffractometer (XRD), transmission electron microscopy, field emission scanning electron microscope, energy dispersive spectroscopy (EDS), Fourier transformed‐infrared spectrums (FTIR), thermo gravimetric analysis, differential scanning calorimeter, and vibrating sample magnetometer. XRD patterns shows metastable ε‐cobalt phase in the composite. Tube like morphology with average diameter of 25–35 nm and length up to 1 µm is obtained. Peak assignment of FTIR spectrum reveals that green solid material is polyaniline and incorporation of cobalt in polyaniline matrix leads structural change. EDS also indicates the presence of cobalt in the nanocomposite. Enhancement in thermal stability is obtained for nanocomposite. Superparamagnetism is obtained in the nanocomposite from dc magnetic measurement and ac susceptibility measurement. POLYM. COMPOS. 36:489–496, 2015. © 2014 Society of Plastics Engineers
Annealing of gold nanoparticles on GaP(111)B: initial stage of GaP nanowire growth
Authors: Eliáš Peter , Hasenöhrl Stanislav , Laurencíková Agáta , Rosová Alica , Novák Jozef
Published: March 2014

GaP(111)B substrate was strewn with 30 nm colloidal Au nanoparticles. Organic residues were removed by: A) boiling in acetone and isopropylalcohol followed by a DI water rinse, B) treatment A + HF:H2O, C) treatment A + O2 plasma for 10 min, 20 min, and 40 min, and D) treatment A combined with O2 plasma (10 min) and HF:H2O. The substrate thus had original ‘epi‐ready' oxides (A), or fresh native oxides (B and D), or new added oxides (C). The samples were annealed at Ta = 650 °C for 10 min under PH3 and H2 in an MOVPE chamber. This resulted in the growth of GaP stumps along [111]B on each sample. Their length was <3 nm (B and D), ∼20 nm (A), and ∼220 nm (C 40 min). Elemental Ga is left as P2O5/Ga2O3 oxides form on etched GaP(111)B at room temperature. We believe that as the oxides disintegrated during annealing, they released the elemental Ga that combined with phosphorus from PH3, and this led to the growth of the GaP stumps. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear fractional‐order power system stabilizer for multi‐machine power systems based on sliding mode technique
Authors: Majidabad Sajjad Shoja , Shandiz Heydar Toosian , Hajizadeh Amin
Published: March 2014

This paper presents two novel nonlinear fractional‐order sliding mode controllers for power angle response improvement of multi‐machine power systems. First, a nonlinear block control is used to handle nonlinearities of the interconnected power system. In the second step, a decentralized fractional‐order sliding mode controller with a nonlinear sliding manifold is designed. Practical stability is achieved under the assumption that the upper bound of the fractional derivative of perturbations and interactions are known. However, when an unknown transient perturbation occurs in the system, it makes the evaluation of perturbation and interconnection upper bound troublesome. In the next step, an adaptive‐fuzzy approximator is applied to fix the mentioned problem. The fuzzy approximator uses adjacent generators relative speed as own inputs, which is known as semi‐decentralized control strategy. For both cases, the stability of the closed‐loop system is analyzed by the fractional‐order stability theorems. Simulation results for a three‐machine power system with two types of faults are illustrated to show the performance of the proposed robust controllers versus the conventional sliding mode. Additionally, the fractional parameter effects on the system transient response and the excitation voltage amplitude and chattering are demonstrated in the absence of the fuzzy approximator. Finally, the suggested controller is combined with a simple voltage regulator in order to keep the system synchronism and restrain the terminal voltage variations at the same time. Copyright © 2014 John Wiley & Sons, Ltd.
Polyhydroxylated Metallofullerenols Stimulate IL‐1β Secretion of Macrophage through TLRs/MyD88/NF‐κB Pathway and NLRP3 Inflammasome Activation
Authors: Chen Zhiyun , Liu Ying , Sun Baoyun , Li Han , Dong Jinquan , Zhang Lijuan , Wang Liming , Wang Peng , Zhao Yuliang , Chen Chunying
Published: March 2014

Polyhydroxylated fullerenols especially gadolinium endohedral metallofullerenols (Gd@C82(OH)22) are shown as a promising agent for antitumor chemotherapeutics and good immunoregulatory effects with low toxicity. However, their underlying mechanism remains largely unclear. We found for the first time the persistent uptake and subcellular distribution of metallofullerenols in macrophages by taking advantages of synchrotron‐based scanning transmission X‐ray microscopy (STXM) with high spatial resolution of 30 nm. Gd@C82(OH)22 can significantly activate primary mouse macrophages to produce pro‐inflammatory cytokines like IL‐1β. Small interfering RNA (siRNA) knockdown shows that NLRP3 inﬂammasomes, but not NLRC4, participate in fullerenol‐induced IL‐1β production. Potassium efflux, activation of P2X7 receptor and intracellular reactive oxygen speciesare also important factors required for fullerenols‐induced IL‐1β release. Stronger NF‐κB signal triggered by Gd@C82(OH)22 is in agreement with higher pro‐IL‐1β expression than C60(OH)22. Interestingly, TLR4/MyD88 pathway but not TLR2 mediates IL‐1β secretion in Gd@C82(OH)22 exposure confirmed by macrophages from MyD88−/−/TLR4−/−/TLR2−/− knockout mice, which is different from C60(OH)22. Our work demonstrated that fullerenols can greatly activate macrophage and promote IL‐1β production via both TLRs/MyD88/NF‐κB pathway and NLRP3 inflammasome activation, while Gd@C82(OH)22 had stronger ability C60(OH)22 due to the different electron affinity on the surface of carbon cage induced by the encaged gadolinium ion.
Magneto‐Plasmonic Au‐Fe Alloy Nanoparticles Designed for Multimodal SERS‐MRI‐CT Imaging
Authors: Amendola Vincenzo , Scaramuzza Stefano , Litti Lucio , Meneghetti Moreno , Zuccolotto Gaia , Rosato Antonio , Nicolato Elena , Marzola Pasquina , Fracasso Giulio , Anselmi Cristina , Pinto Marcella , Colombatti Marco
Published: March 2014

Diagnostic approaches based on multimodal imaging are needed for accurate selection of the therapeutic regimens in several diseases, although the dose of administered contrast drugs must be reduced to minimize side effects. Therefore, large efforts are deployed in the development of multimodal contrast agents (MCAs) that permit the complementary visualization of the same diseased area with different sensitivity and different spatial resolution by applying multiple diagnostic techniques. Ideally, MCAs should also allow imaging of diseased tissues with high spatial resolution during surgical interventions. Here a new system based on multifunctional Au‐Fe alloy nanoparticles designed to satisfy the main requirements of an ideal MCA is reported and their biocompatibility and imaging capability are described. The MCAs show easy and versatile surface conjugation with thiolated molecules, magnetic resonance imaging (MRI) and computed X‐ray tomography (CT) signals for anatomical and physiological information (i.e., diagnostic and prognostic imaging), large Raman signals amplified by surface enhanced Raman scattering (SERS) for high sensitivity and high resolution intrasurgical imaging, biocompatibility, exploitability for in vivo use and capability of selective accumulation in tumors by enhanced permeability and retention effect. Taken together, these results show that Au‐Fe nanoalloys are excellent candidates as multimodal MRI‐CT‐SERS imaging agents.
Analysis of compaction initiation in human embryos by using time-lapse cinematography
Authors: Iwata Kyoko , Yumoto Keitaro , Sugishima Minako , Mizoguchi Chizuru , Kai Yoshiteru , Iba Yumiko , Mio Yasuyuki
Published: March 2014

Purpose

To analyze the initiation of compaction in human embryos in vitro by using time-lapse cinematography (TLC), with the goal of determining the precise timing of compaction and clarifying the morphological changes underlying the compaction process.

Methods

One hundred and fifteen embryos donated by couples with no further need for embryo-transfer were used in this study. Donated embryos were thawed and processed, and then their morphological behavior during the initiation of compaction was dynamically observed via time-lapse cinematography (TLC) for 5 days.

Results

Although the initiation of compaction occurred throughout the period from the 4-cell to 16-cell stage, 99 (86.1 %) embryos initiated compaction at the 8-cell stage or later, with initiation at the 8-cell stage being most frequent (22.6 %). Of these 99 embryos, 49.5 % developed into good-quality blastocysts. In contrast, of the 16 (13.9 %) embryos that initiated compaction prior to the 8-cell stage, only 18.8 % developed into good-quality blastocysts. Embryos that initiated compaction before the 8-cell stage showed significantly higher numbers of multinucleated blastomeres, due to asynchronism in nuclear division at the third mitotic division resulting from cytokinetic failure.

Conclusions

The initiation of compaction primarily occurs at the third mitotic division or later in human embryos. Embryos that initiate compaction before the 8-cell stage are usually associated with aberrant embryonic development (i.e., cytokinetic failure accompanied by karyokinesis).
Direct evidence of central European forest refugia during the last glacial period based on mollusc fossils
Authors: Juřičková Lucie , Horáčková Jitka , Ložek Vojen
Published: March 2014

Although there is evidence from molecular studies for the existence of central European last glacial refugia for temperate species, there is still a great lack of direct fossil records to confirm this theory. Here we bring such evidence in the form of fossil shells from twenty strictly forest land snail species, which were recorded in radiocarbon-dated late glacial or older mollusc assemblages of nine non-interrupted mollusc successions situated in the Western Carpathians, and one in the Bohemian Massif. We proposed that molluscs survived the last glacial period in central Europe in isolated small patches of broadleaf forest, which we unequivocally demonstrate for two sites of last glacial maximum age.
Primary undifferentiated high‐grade pleomorphic sarcoma/malignant fibrous histiocytoma arising from the mandible
Authors: Mori Yoshiyuki , Motoi Toru , Ida Komei , Shibahara Junji , Saijo Hideto , Susami Takafumi , Takato Tsuyoshi
Published: March 2014

A patient who had a primary undifferentiated high‐grade pleomorphic sarcoma/malignant fibrous histiocytoma that apparently arose in the mandible, but showed uncertain differentiation on histopathological examination, is described. Our regimen, a combination of pre‐ and postoperative chemotherapy and surgical resection, produced a good outcome.
The gametogenic cycle and life history ofNicolea uspiana(Polychaeta: Terebellidae) on the south-east coast of Brazil
Authors: Garraffoni André Rinaldo Senna , Yokoyama Leonardo Querobim , Amaral Antonia Cecília Zacagnini
Published: March 2014

The gametogenic cycle and life history ofNicolea uspiana(Nogueira, 2003) (Polychaeta: Terebellidae) was studied by taking monthly samples over a 13 month period. Each month, 10 females were sorted; 50 oocytes were removed from the coelom of each specimen, and the maximum diameter was determined. Additionally, 10 males were sorted and 100 gametes were randomly selected from each specimen to evaluate their shape and maturation stage. This species is gonochoric and exhibits slight external sexual dimorphism (in the shape of the nephridial papillae). The sex-ratio ofN. uspianawas 2.4 male for each female. The initial gametic stages of both sexes are produced in special structures called nephromixia. Oogenesis is extra-ovarian, and the germ cells are clumped and surrounded by follicle cells. These cells are ovulated into the coelomic fluid, and yolk synthesis occurs in this cavity. The maximum diameter of oocytes measured, 225 µm, showed that these eggs fall into the size-range for lecithotrophy. Furthermore,N. uspianais an iteroparous species, as the mature individuals can breed several times during their lifetime. Male gonads release germ cells early in development, and sperm maturation also occurs in the coelomic fluid. The male gametes consist of flattened plaques of germ cells attached on their anterior part by a cytophore assuming a rosette-like appearance. Following maturation of the male cells, the spermatids produce arrays of stiffly vibratile tails, assuming a morula shape. The reproductive patterns and life history of the terebellids are also discussed.
Malcolm Roy Clarke, FRS
Authors: Rodhouse Paul G.K. , Lu Chung-Cheng , Roper Clyde F.E.
Published: March 2014

Malcolm Roy Clarke, FRS (1930–2013) made lasting contributions to cephalopod biology through his productive research programme, his commitment to furthering cephalopod biology and his congenial spirit. His professional legacy includes many important contributions. He wrote over 150 scientific papers, book chapters and other scholarly works, including, the Discovery Report on the role of cephalopods in the diet of sperm whales in the Southern Hemisphere, he edited A handbook for the identification of cephalopod beaks, which made the study of trophic interactions more accessible, and with colleagues he developed and instituted the Cephalopod International Advisory Council to provide advice on cephalopods and a framework for international meetings. His impact on marine science was broad and longstanding.
Paranoia in the Therapeutic Relationship in Cognitive Behavioural Therapy for Psychosis
Authors: Lawlor Caroline , Hall Katherine , Ellett Lyn
Published: March 2014

Background and aims: This study explored therapists’ and clients’ experiences of paranoia about the therapist in cognitive behaviour therapy. Method: Ten therapists and eight clients engaged in cognitive behaviour therapy for psychosis were interviewed using a semi-structured interview. Data were analyzed using thematic analysis. Results: Clients reported experiencing paranoia about their therapist, both within and between therapy sessions. Therapists’ accounts highlighted a number of dilemmas that can arise in responding to clients’ paranoia about them. Conclusions: The findings highlight helpful ways of working with clients when they become paranoid about their therapist, and emphasize the importance of developing a therapeutic relationship that is radically collaborative, supporting a person-based approach to distressing psychotic experience.
CX3CR1 delineates temporally and functionally distinct subsets of myeloid‐derived suppressor cells in a mouse model of ovarian cancer
Authors: Hart Kevin M , Usherwood Edward J , Berwin Brent L
Published: March 2014

Expression of the chemokine receptor CX3CR1 has been used to identify distinct populations within the monocyte, macrophage and dendritic cell lineages. Recent evidence indicates that CX3CR1‐positive subsets of myeloid cells play distinct and important roles in a wide range of immunological maladies, and thus the use of CX3CR1 expression has leveraged our understanding of the myeloid contribution to a multitude of diseases. Here we use CX3CR1 expression as a means to identify a novel nongranulocytic CX3CR1‐negative myeloid population that is functionally distinct from the previously described CX3CR1‐positive cellular subsets within the CD11b‐positive cellular compartment of ascites from ovarian tumor‐bearing mice. We functionally identify CX3CR1‐negative cells as myeloid suppressor cells and as a cellular subset with pathological specificity. Importantly, the CX3CR1‐negative cells exhibit early IL‐10 production in the ovarian tumor microenvironment, which we have shown to be critically tied to suppression and additional myeloid‐derived suppressor cell accumulation, and we now show that this cellular population actively contributes to tumor progression. Furthermore, we demonstrate that the CX3CR1‐negative population is derived from the recently described CX3CR1‐positive macrophage/dendritic cell precursor cell. These studies provide a greater understanding of the generation and maintenance of regulatory myeloid subsets and have broad implications for the elucidation of myeloid function and contributions within the tumor microenvironment.
Highly sensitive and specific detection of histamine via the formation of a self-assembled magic number cluster with thymine by mass spectrometry
Authors: Sun Jiamu , Qin Zhen , Liu Jia , Zhang Chengsen , Luo Hai
Published: March 2014

The self-assembled magic number cluster of thymine (T) significantly enhanced the MS signal of histamine with high specificity.
High-turnover visible-light photoreduction of CO2 by a Re(i) complex stabilized on dye-sensitized TiO2
Authors: Ha Eun-Gyeong , Chang Jeong-Ah , Byun Sung-Min , Pac Chyongjin , Jang Dong-Myung , Park Jeunghee , Kang Sang Ook
Published: March 2014

Higher photocatalytic CO2 conversion to CO with a turnover number of 435 was achieved by the ternary dye-sensitized systems comprising a dye/TiO2/Re platform.
The influence of H-bonding on the ‘ambidentate’ coordination behaviour of the thiocyanate ion to Cd(ii): a combined experimental and theoretical study
Authors: Hazari Alokesh , Das Lakshmi Kanta , Bauzá Antonio , Frontera Antonio , Ghosh Ashutosh
Published: March 2014

The importance of H-bonding in stabilizing the unusual S-coordination of the thiocyanate ion to Cd(ii) in hetero-metallic Cu2Cd compounds has been established by structural analyses and DFT studies.
Synthesis and phase behavior of a new 2-vinylbiphenyl-based mesogen-jacketed liquid crystalline polymer with a high glass transition temperature and low threshold molecular weight
Authors: Zhang Qi-Kai , Tian Hai-Jian , Li Chang-Feng , Zhu Yu-Feng , Liang Yongri , Shen Zhihao , Fan Xing-He
Published: March 2014

A new mesogen-jacketed liquid crystalline (LC) polymer was synthesized by NMP. It has a high Tg and a relatively low threshold MW for LC formation.
One-step prepared fluorescent copper nanoclusters for reversible pH-sensing
Authors: Wang Wei , Leng Fei , Zhan Lei , Chang Yong , Yang Xiao Xi , Lan Jing , Huang Cheng Zhi
Published: March 2014

A one-step synthesis of water soluble and pH-responsive trypsin-stabilized fluorescent CuNCs was reported without using additional protective or reducing agents.
A PEGylated-rhodamine based sensor for “turn-on” fluorimetric and colorimetric detection of Hg2+ ions in aqueous media
Authors: Hazra Subhenjit , Balaji Shruti , Banerjee Mainak , Ganguly Anasuya , Ghosh Narendra Nath , Chatterjee Amrita
Published: March 2014

A water soluble turn-on fluorescent probe for the detection of mercury ions in purely aqueous media a has been developed by appending a water-compatible PEG-unit onto a rhodamine derivative. It has high selectivity for Hg2+ ions and is fairly non-toxic in intercellular studies.
Electrical tuning of spin current in a boron nitride nanotube quantum dot
Authors: Dhungana Kamal B. , Pati Ranjit
Published: March 2014

Controlling spin current and magnetic exchange coupling by applying an electric field and achieving high spin injection efficiency at the same time in a nanostructure coupled to ferromagnetic electrodes have been the outstanding challenges in nanoscale spintronics.
A new fluorescent probe for Zn2+with red emission and its application in bioimaging
Authors: Tan Yiqun , Liu Min , Gao Junkuo , Yu Jiancan , Cui Yuanjing , Yang Yu , Qian Guodong
Published: March 2014

Selectively probing Zn2+in vivo! A new fluorescent probe highly sensitive and selective for Zn2+based on the ICT effect was designed. This probe showed potential application in biology.
Assessing the improved performance of freestanding, flexible graphene and carbon nanotube hybrid foams for lithium ion battery anodes
Authors: Cohn Adam P. , Oakes Landon , Carter Rachel , Chatterjee Shahana , Westover Andrew S. , Share Keith , Pint Cary L.
Published: March 2014

Freestanding, flexible graphene–SWNT foams give promise for Li-ion batteries due to synergistic roles of these hybrid materials in Li storage.
A novel method to improve the thermal stability of poly(propylene carbonate)
Authors: An Jingjing , Ke Yucai , Cao Xinyu , Ma Yongmei , Wang Fosong
Published: March 2014

The introduction of NP-10P by simple melt-blending can significantly improve the thermal stability of PPC. This new finding will facilitate development and widespread applications of this biodegradable material.
A novel three-dimensional graphene/bacterial cellulose nanocomposite prepared by in situ biosynthesis
Authors: Luo Honglin , Xiong Guangyao , Yang Zhiwei , Raman Sudha R. , Si Hongjuan , Wan Yizao
Published: March 2014

A novel graphene/bacterial cellulose nanocomposite hydrogel was prepared by adding a graphene suspension into the culture medium of bacterial cellulose.
Universal solution-processed high-k amorphous oxide dielectrics for high-performance organic thin film transistors
Authors: Zhao Xurong , Wang Sumei , Li Aiju , Ouyang Jun , Xia Guodong , Zhou Ji
Published: March 2014

Solution-processed high-k ZrTiOx dielectric films achieve a k value and capacitance of 53 and 467 nF cm−2, and a low leakage current of 4 × 10−8 A cm−2 with polymer modification. High-performance organic thin film transistors with a carrier mobility of 0.58 cm2 V−1 s−1, and a low operating voltage of 6 V were realized with ZrTiOx dielectric films.
Design of CuO–TiO2 heterostructure nanofibers and their sensing performance
Authors: Deng Jianan , Wang Lili , Lou Zheng , Zhang Tong
Published: March 2014

Novel CuO nanocube-functionalized TiO2 heterostructure nanofibers were fabricated by a simple two-step method, and exhibited excellent sensing response and selectivity.
Multipath error mitigation using self‐encoded spread spectrum for binary‐offset‐carrier signals
Authors: Duraisamy Poomathi , Jang Won Mee , Nguyen Lim , Steiner Austin
Published: March 2014

Self‐encoded spread spectrum (SESS) incorporated with binary‐offset‐carrier modulation can significantly improve the navigation accuracy exploiting the inherent temporal diversity of iterative detection (ID). ID is the natural realisation of the detection scheme based on the unique SESS spreading sequence that comes from the data source itself. The enhanced precision is presented in terms of multipath error envelope, running average error and root‐mean‐square error for early‐minus‐late and elary/late slope. SESS is a promising technology that can substantially mitigate detrimental effects of multipath on tracking error for position location or navigation. The accuracy of SESS with ID is superior to other conventional correlation detection schemes with a similar or minimally increased computational complexity.
Reference Correlations for the Density and Viscosity of Squalane from 273 to 473 K at Pressures to 200 MPa
Authors: Mylona Sofia K. , Assael Marc J. , Comuñas María J. P. , Paredes Xavier , Gaciño Félix M. , Fernández Josefa , Bazile Jean Patrick , Boned Christian , Daridon Jean Luc , Galliero Guillaume , Pauly Jérôme , Harris Kenneth R.
Published: March 2014

This paper presents new reference correlations for both the density and viscosity of squalane at high pressure. These correlations are based on critically evaluated experimental data taken from the literature. In the case of the density, the correlation, based on the Tait equation, is valid from 273 to 473 K at pressures to 200 MPa. At 0.1 MPa, it has an average absolute deviation of 0.03%, a bias of −0.01%, and an expanded uncertainty (at the 95% confidence level) of 0.06%. Over the whole range of pressures, the density correlation has an average absolute deviation of 0.05%, a bias of −0.004%, and an expanded uncertainty (at the 95% confidence level) of 0.18%. In the case of the viscosity, two correlations are presented, one a function of density and temperature, based on the Assael-Dymond model, and the other a function of temperature and pressure, based on a modified Vogel-Fulcher-Tammann equation. The former is slightly superior to the latter at high temperatures (above 410 K), whereas the reverse is true at low temperatures, where the viscosity is strongly temperature dependent. In the temperature range from 320 to 473 K at pressures to 200 MPa, the first correlation has an average absolute deviation of 1.41%, a bias of −0.09%, and an expanded uncertainty (at the 95% confidence level) of 3%. Below 320 K, deviations from the present scheme rise to a maximum of 20%. In the temperature range from 278 to 473 K at pressures to 200 MPa, the second viscosity correlation has an average absolute deviation of 1.7%, a bias of −0.04%, and an expanded uncertainty (at the 95% confidence level) of 4.75%.
Electronic and structural properties at the interface between iron-phthalocyanine and Cu(110)
Authors: Hu Fang , Mao Hongying , Zhang Hanjie , Wu Ke , Cai Yiliang , He Pimo
Published: March 2014

Electronic structure and adsorption geometry of Iron-Phthalocyanine (FePc) adsorbed on Cu(110) were investigated by using ultraviolet photoelectron spectroscopy (UPS) and first-principles density functional theory (DFT) calculations. The emission features α, β, γ, and δ originating from the FePc molecules in UPS spectra are located at 3.42, 5.04, 7.36, and 10.28 eV below Fermi level. The feature α is mostly deriving from Fe 3d orbital with some contributions from C 2p orbital. A considerable charge transfer from the Cu substrate to the Fe 3d orbital occurs upon the adsorption of FePc molecules. The angle-resolved UPS measurements indicate that FePc molecules adopt lying-down configurations with their molecular plane nearly parallel to the Cu(110) substrate at monolayer stage. In combination with the DFT calculations, the adsorption structure is determined to be that FePc molecule adsorbs on the top site of Cu(110) with an angle of 45° between the lobes of FePc and the $[1\bar 10]$[11¯0] azimuth of the substrate.
Time-resolved photoluminescence from defects in n-type GaN
Authors: Reshchikov M. A.
Published: March 2014

Point defects in GaN were studied with time-resolved photoluminescence (PL). The effects of temperature and excitation intensity on defect-related PL have been investigated theoretically and experimentally. A phenomenological model, based on rate equations, explains the dependence of the PL intensity on excitation intensity, as well as the PL lifetime and its temperature dependence. We demonstrate that time-resolved PL measurements can be used to find the concentrations of free electrons and acceptors contributing to PL in n-type semiconductors.
Conformational transition of H-shaped branched polymers
Authors: Dasmahapatra Ashok Kumar , Sanka Venkata Mahanth
Published: March 2014

We report dynamic Monte Carlo simulation on conformational transition of H-shaped branched polymers by varying main chain (backbone) and side chain (branch) length. H-shaped polymers in comparison with equivalent linear polymers exhibit a depression of theta temperature accompanying with smaller chain dimensions. We observed that the effect of branches on backbone dimension is more pronounced than the reverse, and is attributed to the conformational heterogeneity prevails within the molecule. With an increase in branch length, backbone is slightly stretched out in the coil and globule state. However, in the pre-collapsed (cf. crumpled globule) state, backbone size decreases with the increase of branch length. We attribute this non-monotonic behavior as the interplay between excluded volume interaction and intra-chain bead-bead attractive interaction during collapse transition. Structural analysis reveals that the inherent conformational heterogeneity promotes the formation of a collapsed structure with segregated backbone and branch units (resembles to “sandwich” or “Janus” morphology) rather an evenly distributed structure consisting of all the units. The shape of the collapsed globule becomes more spherical with increasing either backbone or branch length.
The development of an optically accessible, high-power combustion test rig
Authors: Slabaugh Carson D. , Pratt Andrew C. , Lucht Robert P. , Meyer Scott E. , Benjamin Michael , Lyle Kent , Kelsey Mark
Published: March 2014

This work summarizes the development of a gas turbine combustion experiment which will allow advanced optical measurements to be made at realistic engine conditions. Facility requirements are addressed, including instrumentation and control needs for remote operation when working with high energy flows. The methodology employed in the design of the optically accessible combustion chamber is elucidated, including window considerations and thermal management of the experimental hardware under extremely high heat loads. Experimental uncertainties are also quantified. The stable operation of the experiment is validated using multiple techniques and the boundary conditions are verified. The successful prediction of operating conditions by the design analysis is documented and preliminary data are shown to demonstrate the capability of the experiment to produce high-fidelity datasets for advanced combustion research.
A novel contactless technique for thermal field mapping and thermal conductivity determination: Two-Laser Raman Thermometry
Authors: Reparaz J. S. , Chavez-Angel E. , Wagner M. R. , Graczykowski B. , Gomis-Bresco J. , Alzina F. , Sotomayor Torres C. M.
Published: March 2014

We present a novel contactless technique for thermal conductivity determination and thermal field mapping based on creating a thermal distribution of phonons using a heating laser, while a second laser probes the local temperature through the spectral position of a Raman active mode. The spatial resolution can be as small as 300 nm, whereas its temperature accuracy is ±2 K. We validate this technique investigating the thermal properties of three free-standing single crystalline Si membranes with thickness of 250, 1000, and 2000 nm. We show that for two-dimensional materials such as free-standing membranes or thin films, and for small temperature gradients, the thermal field decays as T(r) ∝ ln(r) in the diffusive limit. The case of large temperature gradients within the membranes leads to an exponential decay of the thermal field, T ∝ exp[ − A·ln(r)]. The results demonstrate the full potential of this new contactless method for quantitative determination of thermal properties. The range of materials to which this method is applicable reaches far beyond the here demonstrated case of Si, as the only requirement is the presence of a Raman active mode.
Role of the reaction intermediates in determining PHIP (parahydrogen induced polarization) effect in the hydrogenation of acetylene dicarboxylic acid with the complex [Rh (dppb)]+ (dppb: 1,4-bis(diphenylphosphino)butane)
Authors: Reineri F. , Aime S. , Gobetto R. , Nervi C.
Published: March 2014

This study deals with the parahydrogenation of the symmetric substrate acetylene dicarboxylic acid catalyzed by a Rh(I) complex bearing the chelating diphosphine dppb (1,4-bis(diphenylphosphino)butane). The two magnetically equivalent protons of the product yield a hyperpolarized emission signal in the 1H-NMR spectrum. Their polarization intensity varies upon changing the reaction solvent from methanol to acetone. A detailed analysis of the hydrogenation pathway is carried out by means of density functional theory calculations to assess the structure of hydrogenation intermediates and their stability in the two solvents. The observed polarization effects have been accounted on the basis of the obtained structures. Insights into the lifetime of a short-lived reaction intermediate are also obtained.
Optical properties of Mn-Co-Ni-O thin films prepared by radio frequency sputtering deposition
Authors: Zhou Wei , Wu Jing , Ouyang Cheng , Gao Yanqing , Xu Xiaofeng , Huang Zhiming
Published: March 2014

Mn1.4Co1.0Ni0.6O4 (MCN) thin films are prepared by RF sputtering deposition method on amorphous Al2O3 substrate. Microstructure and X-ray photoelectron spectroscopy analyses suggest improvements in crystallinity and stoichiometry for MCN films with post-annealed process. Infrared (IR) optical constants of the MCN films are obtained by IR spectroscopic ellipsometer (SE) in the range of 1500 cm−1 to 3200 cm−1 (2.8–6.7 μm). The derived effective charge supports the increase of the oxidation after annealing. The dielectric function of the films is also extracted by SE in the range of 300–1000 nm adopting a double Lorentz model together with a Tauc–Lorentz model. The mechanism in electronic transition process is discussed based on the variation observed in the optical absorption spectra of the as-grown and post-annealed samples. The optical absorption peaks located at 1.7 eV, 2.4–2.6 eV, and 3.5–4 eV are attributed to the charge-transfer transitions of 2p electrons of oxygen ions and 3d electrons of Mn and Co ions. Our results are very important to understand the optoelectronic mechanism and exploit applications of metal oxides.
Note: A timing micro-channel plate detector with backside fast preamplifier
Authors: Wang Wei , Yu Deyang , Lu Rongchun , Liu Junliang , Cai Xiaohong
Published: March 2014

A timing micro-channel plate detector with a backside double-channel fast preamplifier was developed to avoid distortion during signal propagation from the anode to the preamplifier. The mechanical and electronic structure is described. The detector including its backside preamplifier is tested by a 241Am α-source and a rise time of ∼2 ns with an output background noise of 4 mVrms was achieved.
Theoretical study of sum-frequency vibrational spectroscopy on limonene surface
Authors: Zheng Ren-Hui , Wei Wen-Mei , Liu Hao , Jing Yuan-Yuan , Wang Bo-Yang , Shi Qiang
Published: March 2014

By combining molecule dynamics (MD) simulation and quantum chemistry computation, we calculate the surface sum-frequency vibrational spectroscopy (SFVS) of R-limonene molecules at the gas-liquid interface for SSP, PPP, and SPS polarization combinations. The distributions of the Euler angles are obtained using MD simulation, the ψ-distribution is between isotropic and Gaussian. Instead of the MD distributions, different analytical distributions such as the δ-function, Gaussian and isotropic distributions are applied to simulate surface SFVS. We find that different distributions significantly affect the absolute SFVS intensity and also influence on relative SFVS intensity, and the δ-function distribution should be used with caution when the orientation distribution is broad. Furthermore, the reason that the SPS signal is weak in reflected arrangement is discussed.
Effect of boron concentration on recombination at the p-Si–Al2O3 interface
Authors: Black Lachlan E. , Allen Thomas , McIntosh Keith R. , Cuevas Andres
Published: March 2014

We examine the surface passivation properties of Al2O3 deposited on boron-doped planar ⟨100⟩ crystalline silicon surfaces as a function of the boron concentration. Both uniformly doped and diffused surfaces are studied, with surface boron concentrations ranging from 9.2 × 1015 to 5.2 × 1019 cm−3. Atmospheric pressure chemical vapor deposition and thermal atomic layer deposition are used to deposit the Al2O3 films. The surface recombination rate of each sample is determined from photoconductance measurements together with the measured dopant profiles via numerical simulation, using the latest physical models. These values are compared with calculations based on the interface properties determined from capacitance–voltage and conductance measurements. It is found that the fundamental surface recombination velocity of electrons, Sn0, which describes the chemical passivation of the interface, is independent of the surface boron concentration Ns for Ns ≤ 3 × 1019 cm−3, and in excellent agreement with values calculated from the interface state density Dit and capture coefficients cn and cp measured on undiffused boron-doped surfaces. We conclude that the physical properties of the Si–Al2O3 interface are independent of the boron dopant concentration over this range.
A unified radiative magnetohydrodynamics code for lightning-like discharge simulations
Authors: Chen Qiang , Chen Bin , Chen P. F. , Xiong Run , Cai Zhaoyang
Published: March 2014

A two-dimensional Eulerian finite difference code is developed for solving the non-ideal magnetohydrodynamic (MHD) equations including the effects of self-consistent magnetic field, thermal conduction, resistivity, gravity, and radiation transfer, which when combined with specified pulse current models and plasma equations of state, can be used as a unified lightning return stroke solver. The differential equations are written in the covariant form in the cylindrical geometry and kept in the conservative form which enables some high-accuracy shock capturing schemes to be equipped in the lightning channel configuration naturally. In this code, the 5-order weighted essentially non-oscillatory scheme combined with Lax-Friedrichs flux splitting method is introduced for computing the convection terms of the MHD equations. The 3-order total variation diminishing Runge-Kutta integral operator is also equipped to keep the time-space accuracy of consistency. The numerical algorithms for non-ideal terms, e.g., artificial viscosity, resistivity, and thermal conduction, are introduced in the code via operator splitting method. This code assumes the radiation is in local thermodynamic equilibrium with plasma components and the flux limited diffusion algorithm with grey opacities is implemented for computing the radiation transfer. The transport coefficients and equation of state in this code are obtained from detailed particle population distribution calculation, which makes the numerical model is self-consistent. This code is systematically validated via the Sedov blast solutions and then used for lightning return stroke simulations with the peak current being 20 kA, 30 kA, and 40 kA, respectively. The results show that this numerical model consistent with observations and previous numerical results. The population distribution evolution and energy conservation problems are also discussed.
Shot-noise-limited optical Faraday polarimetry with enhanced laser noise cancelling
Authors: Li Jiaming , Luo Le , Carvell Jeff , Cheng Ruihua , Lai Tianshu , Wang Zixin
Published: March 2014

We present a shot-noise-limited measurement of optical Faraday rotations with sub-ten-nanoradian angular sensitivity. This extremely high sensitivity is achieved by using electronic laser noise cancelling and phase sensitive detection. Specially, an electronic laser noise canceller with a common mode rejection ratio of over 100 dB was designed and built for enhanced laser noise cancelling. By measuring the Faraday rotation of ambient air, we demonstrate an angular sensitivity of up to 9.0×10−9 rad/Hz, which is limited only by the shot-noise of the photocurrent of the detector. To date, this is the highest angular sensitivity ever reported for Faraday polarimeters in the absence of cavity enhancement. The measured Verdet constant of ambient air, 1.93(3)×10−9rad/(G cm) at 633 nm wavelength, agrees extremely well with the earlier experiments using high finesse optical cavities. Further, we demonstrate the applications of this sensitive technique in materials science by measuring the Faraday effect of an ultrathin iron film.
Micromagnetic analysis of dynamical bubble-like solitons based on the time domain evolution of the topological density
Authors: Puliafito Vito , Torres Luis , Ozatay Ozhan , Hauet Thomas , Azzerboni Bruno , Finocchio Giovanni
Published: March 2014

Dynamical bubble-like solitons have been recently investigated in nanocontact-based spin-torque oscillators with a perpendicular free layer. Those magnetic configurations can be excited also in different geometries as long as they consist of perpendicular materials. Thus, in this paper, a systematic study of the influence of both external field and high current on that kind of dynamics is performed for a spin-valve point-contact geometry where both free and fixed layers present strong perpendicular anisotropy. The usage of the topological density tool highlights the excitation of complex bubble/antibubble configurations. In particular, at high currents, a deformation of the soliton and its simultaneous shift from the contact area are observed and can be ascribable to the Oersted field. Results provide further detailed information on the excitation of solitons in perpendicular materials for application in spintronics, magnonics, and domain wall logic.
Particle size dependence of heating power in MgFe2O4 nanoparticles for hyperthermia therapy application
Authors: Reza Barati Mohammad , Selomulya Cordelia , Suzuki Kiyonori
Published: March 2014

Magnetic nanoparticles with narrow size distributions have successfully been synthesized by an ultrasonic assisted co-precipitation method. The effects of particle size on magnetic properties, heat generation by AC fields, and the cell cytotoxicity were investigated for MgFe2O4 nanoparticles with mean diameters varying from 7 ± 0.5 nm to 29 ± 1 nm. The critical size for superparamagnetic to ferrimagnetic transition (DS→F) of MgFe2O4 was determined to be about 13 ± 0.5 nm at 300 K. The specific absorption rate (SAR) of MgFe2O4 nanoparticles was strongly size dependent; it showed a maximum value of 19 W/g when the particle size was 10 ± 0.5 nm at which the Néel and Brownian relaxations are the major cause of heating. The SAR value was suppressed dramatically by 46% with increasing particle size from 10 ± 0.5 nm to 13 ± 0.5 nm, where Néel relaxation slows down and SAR results primarily from Brownian relaxation loss. A further reduction in SAR value was evident when the size was increased from 13 ± 0.5 nm to 16 ± 1 nm, where the superparamagnetic to ferromagnetic transition occurs. However, SAR showed a tendency to increase with particle size again above 16 ± 1 nm where hysteresis loss becomes the dominant mechanism of heat generation. The particle size dependence of SAR in the superparamagnetic region was well described by considering the effective relaxation time estimated based on a log-normal size distribution. The clear size dependence of SAR is attributable to the high degree of monodispersity of particles synthesized here. The high SAR value of water-based MgFe2O4 magnetic suspension combined with low cell cytotoxicity suggests a great potential of MgFe2O4 nanoparticles for magnetic hyperthermia therapy applications.
Exploring Ramsey-coherent population trapping atomic clock realized with pulsed microwave modulated laser
Authors: Yang Jing , Tian Yuan , Tan Bozhong , Yun Peter , Gu Sihong
Published: March 2014

A scheme for a Ramsey-coherent population trapping (CPT) atomic clock that eliminates the acousto-optic modulator (AOM) is proposed and experimentally studied. Driven by a periodically microwave modulated current, the vertical-cavity surface-emitting laser emits a continuous beam that switches between monochromatic and multichromatic modes. Ramsey-CPT interference has been studied with this mode-switching beam. In eliminating the AOM, which is used to generate pulsed laser in conventional Ramsey-CPT atomic clock, the physics package of the proposed scheme is virtually the same as that of a conventional compact CPT atomic clock, although the resource budget for the electronics will slightly increase as a microwave switch should be added. By evaluating and comparing experimentally recorded signals from the two Ramsey-CPT schemes, the short-term frequency stability of the proposed scheme was found to be 46% better than the scheme with AOM. The experimental results suggest that the implementation of a compact Ramsey-CPT atomic clock promises better frequency stability.
Evaluation of interface state density of strained-Si metal-oxide-semiconductor interfaces by conductance method
Authors: Cai Weili , Takenaka Mitsuru , Takagi Shinichi
Published: March 2014

In this study, the application of the conductance method to bi-axially strained-Si (sSi) MOS capacitors on relaxed SiGe buffer layers is examined for evaluating the properties of sSi MOS interface states. It is found that the conventional conductance method does not work well for the characterization of SiO2/sSi MOS interfaces, because of additional parasitic admittance related to the sSi/SiGe hetero-interface. This additional parasitic admittance cannot be eliminated by the series resistance correction (SRC). A new equivalent circuit model for the SiO2/sSi interfaces, utilized in the conductance analysis, is proposed. The proposed model takes the sSi/SiGe hetero-interface parasitic admittance into account. By employing this new model and the analysis by a device simulator, physical parameters of the SiO2/sSi MOS interface states, generated by Fowler-Nordheim stress, are extracted. It is found that the introduced biaxial tensile strain does not strongly change the properties of SiO2/Si interface states.
Organic photovoltaic cells with controlled polarization sensitivity
Authors: Awartani Omar , Kudenov Michael W. , O'Connor Brendan T.
Published: March 2014

In this study, we demonstrate linearly polarized organic photovoltaic cells with a well-controlled level of polarization sensitivity. The polarized devices were created through the application of a large uniaxial strain to the bulk heterojunction poly(3-hexylthiophene):Phenyl-C61-butyric acid methyl ester (P3HT:PCBM) film and printing the plastically deformed active layer onto a PEDOT:PSS and indium tin oxide coated glass substrate. The P3HT:PCBM layer is processed such that it is able to accommodate high strains (over 100%) without fracture. After printing the strained films, thermal annealing is used to optimize solar cell performance while maintaining polarization sensitivity. A dichroic ratio and short circuit current ratio of ≈6.1 and ≈1.6 were achieved, respectively.