bluuebunny/crossref_metadata_2025 huggingface dataset:
Direct synthesis of nanodiamonds by femtosecond laser irradiation of ethanol
Authors: Nee Chen-Hon , Yap Seong-Ling , Tou Teck-Yong , Chang Huan-Cheng , Yap Seong- Shan
Published: September 2016

Carbon nanomaterials exhibit novel characteristics including enhanced thermal, electrical, mechanical and biological properties. Nanodiamonds; first discovered in meteorites are found to be biocompatible, non-toxic and have distinct optical properties. Here we show that nanodiamonds with the size of <5 nm are formed directly from ethanol via 1025 nm femtosecond laser irradiation. The absorption of laser energy by ethanol increased non-linearly above 100 μJ accompanied by a white light continuum arises from fs laser filamentation. At laser energy higher than 300 μJ, emission spectra of C, O and H in the plasma were detected, indicating the dissociation of C2H5OH. Nucleation of the carbon species in the confined plasma within the laser filaments leads to the formation of nanodiamonds. The energy dependence and the roles of the nonlinear phenomenon to the formation of homogeneous nanodiamonds are discussed. This work brings new possibility for bottom-up nanomaterials synthesis based on nano and ultrafast laser physics.
Full-Color Biomimetic Photonic Materials with Iridescent and Non-Iridescent Structural Colors
Authors: Kawamura Ayaka , Kohri Michinari , Morimoto Gen , Nannichi Yuri , Taniguchi Tatsuo , Kishikawa Keiki
Published: September 2016

The beautiful structural colors in bird feathers are some of the brightest colors in nature and some of these colors are created by arrays of melanin granules that act as both structural colors and scattering absorbers. Inspired by the color of bird feathers, high-visibility structural colors have been created by altering four variables: size, blackness, refractive index and arrangement of the nano-elements. To control these four variables, we developed a facile method for the preparation of biomimetic core-shell particles with melanin-like polydopamine (PDA) shell layers. The size of the core-shell particles was controlled by adjusting the core polystyrene (PSt) particles’ diameter and the PDA shell thicknesses. The blackness and refractive index of the colloidal particles could be adjusted by controlling the thickness of the PDA shell. The arrangement of the particles was controlled by adjusting the surface roughness of the core-shell particles. This method enabled the production of both iridescent and non-iridescent structural colors from only one component. This simple and novel process of using core-shell particles containing PDA shell layers can be used in basic research on structural colors in nature and their practical applications.
A 2D virtual reality system for visual goal-driven navigation in zebrafish larvae
Authors: Jouary Adrien , Haudrechy Mathieu , Candelier Raphaël , Sumbre German
Published: September 2016

Animals continuously rely on sensory feedback to adjust motor commands. In order to study the role of visual feedback in goal-driven navigation, we developed a 2D visual virtual reality system for zebrafish larvae. The visual feedback can be set to be similar to what the animal experiences in natural conditions. Alternatively, modification of the visual feedback can be used to study how the brain adapts to perturbations. For this purpose, we first generated a library of free-swimming behaviors from which we learned the relationship between the trajectory of the larva and the shape of its tail. Then, we used this technique to infer the intended displacements of head-fixed larvae, and updated the visual environment accordingly. Under these conditions, larvae were capable of aligning and swimming in the direction of a whole-field moving stimulus and produced the fine changes in orientation and position required to capture virtual prey. We demonstrate the sensitivity of larvae to visual feedback by updating the visual world in real-time or only at the end of the discrete swimming episodes. This visual feedback perturbation caused impaired performance of prey-capture behavior, suggesting that larvae rely on continuous visual feedback during swimming.
Systematical Evaluation of Mechanically Strong 3D Printed Diluted magnesium Doping Wollastonite Scaffolds on Osteogenic Capacity in Rabbit Calvarial Defects
Authors: Sun Miao , Liu An , Shao Huifeng , Yang Xianyan , Ma Chiyuan , Yan Shigui , Liu Yanming , He Yong , Gou Zhongru
Published: September 2016

Wollastonite (CaSiO3; CSi) ceramic is a promising bioactive material for bone defect repair due to slightly fast degradation of its porous constructs in vivo. In our previous strategy some key features of CSi ceramic have been significantly improved by dilute magnesium doping for regulating mechanical properties and biodegradation. Here we demonstrate that 6 ~ 14% of Ca substituted by Mg in CSi (CSi-Mgx, x = 6, 10, 14) can enhance the mechanical strength (>40 MPa) but not compromise biological performances of the 3D printed porous scaffolds with open porosity of 60‒63%. The in vitro cell culture tests in vitro indicated that the dilute Mg doping into CSi was beneficial for ALP activity and high expression of osteogenic marker genes of MC3T3-E1 cells in the scaffolds. A good bone tissue regeneration response and elastoplastic response in mechanical strength in vivo were determined after implantation in rabbit calvarial defects for 6‒12 weeks. Particularly, the CSi-Mg10 and CSi-Mg14 scaffolds could enhance new bone regeneration with a significant increase of newly formed bone tissue (18 ~ 22%) compared to the pure CSi (~14%) at 12 weeks post-implantation. It is reasonable to consider that, therefore, such CSi-Mgx scaffolds possessing excellent strength and reasonable degradability are promising for bone reconstruction in thin-wall bone defects.
Sweeter and stronger: enhancing sweetness and stability of the single chain monellin MNEI through molecular design
Authors: Leone Serena , Pica Andrea , Merlino Antonello , Sannino Filomena , Temussi Piero Andrea , Picone Delia
Published: September 2016

Sweet proteins are a family of proteins with no structure or sequence homology, able to elicit a sweet sensation in humans through their interaction with the dimeric T1R2-T1R3 sweet receptor. In particular, monellin and its single chain derivative (MNEI) are among the sweetest proteins known to men. Starting from a careful analysis of the surface electrostatic potentials, we have designed new mutants of MNEI with enhanced sweetness. Then, we have included in the most promising variant the stabilising mutation E23Q, obtaining a construct with enhanced performances, which combines extreme sweetness to high, pH-independent, thermal stability. The resulting mutant, with a sweetness threshold of only 0.28 mg/L (25 nM) is the strongest sweetener known to date. All the new proteins have been produced and purified and the structures of the most powerful mutants have been solved by X-ray crystallography. Docking studies have then confirmed the rationale of their interaction with the human sweet receptor, hinting at a previously unpredicted role of plasticity in said interaction.
Characterization and Comparative Genomic Analyses of Pseudomonas aeruginosa Phage PaoP5: New Members Assigned to PAK_P1-like Viruses
Authors: Shen Mengyu , Le Shuai , Jin Xiaolin , Li Gang , Tan Yinling , Li Ming , Zhao Xia , Shen Wei , Yang Yuhui , Wang Jing , Zhu Hongbin , Li Shu , Rao Xiancai , Hu Fuquan , Lu Shuguang
Published: September 2016

As a potential alternative to antibiotics, phages can be used to treat multi-drug resistant bacteria. As such, the biological characteristics of phages should be investigated to utilize them as effective antimicrobial agents. In this study, phage PaoP5, a lytic virus that infects Pseudomonas aeruginosa PAO1, was isolated and genomically characterized. PaoP5 comprises an icosahedral head with an apex diameter of 69 nm and a contractile tail with a length of 120 nm. The PaoP5 genome is a linear dsDNA molecule containing 93,464 base pairs (bp) with 49.51% G + C content of 11 tRNA genes and a 1,200 bp terminal redundancy. A total of 176 protein-coding genes were predicted in the PaoP5 genome. Nine PaoP5 structural proteins were identified. Three hypothetical proteins were determined as structural. Comparative genomic analyses revealed that seven new Pseudomonas phages, namely, PaoP5, K8, C11, vB_PaeM_C2-10_Ab02, vB_PaeM_C2-10_Ab08, vB_PaeM_C2-10_Ab10 and vB_PaeM_C2-10_Ab15, were similar to PAK_P1-like viruses. Phylogenetic and pan-genome analyses suggested that the new phages should be assigned to PAK_P1-like viruses, which possess approximately 100 core genes and 150 accessory genes. This work presents a detailed and comparative analysis of PaoP5 to enhance our understanding of phage biology.
Protein Kinase D2 Protects against Acute Colitis Induced by Dextran Sulfate Sodium in Mice
Authors: Xiong Jing , Zhou Ming-feng , Wang Ya-dong , Chen Li-ping , Xu Wan-fu , Wang Yao-dong , Deng Fan , Liu Si-de
Published: September 2016

Inflammatory bowel disease is characterized by dysregulation of the mucosal immune system resulting from impaired intestinal epithelial barrier function. Protein kinase D2 has been implicated in the regulation of immune responses. The present study was to define PKD2 might affect murine colitis. Colitis was induced in wild-type mice (PKD2WT/WT) and PKD2 catalytic activity deficient mice (PKD2SSAA/SSAA) with dextran sulfate sodium. PKD2SSAA-knockin mice displayed catalytic activity deficiency and increased susceptibility to DSS-induced colitis with enhanced weight loss, colonic inflammation compared with PKD2WT/WTmice. Furthermore, crucial inflammatory cytokines mRNA levels in PKD2SSAA-knockin mice were higher than controls accompanied with down-regulation of ZO-1, MUC2 and intestinal barrier dysfunction. However, there were no differences in the proliferation or apoptosis of intestinal epithelial cells in PKD2SSAA-knockin mice compared with wild-type controls. In addition, PKD2 expression was repressed in patients with IBD compared with healthy controls. These studies suggested that activation of PKD2 in the colonic epithelium microenvironment may contribute to protect against DSS-induced colitis through regulation of intestinal mucosal immunity and barrier function.
Genome-wide long non-coding RNA screening, identification and characterization in a model microorganism Chlamydomonas reinhardtii
Authors: Li Hui , Wang Yuting , Chen Meirong , Xiao Peng , Hu Changxing , Zeng Zhiyong , Wang Chaogang , Wang Jiangxin , Hu Zhangli
Published: September 2016

Microalgae are regarded as the most promising biofuel candidates and extensive metabolic engineering were conducted but very few improvements were achieved. Long non-coding RNA (lncRNA) investigation and manipulation may provide new insights for this issue. LncRNAs refer to transcripts that are longer than 200 nucleotides, do not encode proteins but play important roles in eukaryotic gene regulation. However, no information of potential lncRNAs has been reported in eukaryotic alga. Recently, we performed RNA sequencing in Chlamydomonas reinhardtii, and obtained totally 3,574 putative lncRNAs. 1440 were considered as high-confidence lncRNAs, including 936 large intergenic, 310 intronic and 194 anti-sense lncRNAs. The average transcript length, ORF length and numbers of exons for lncRNAs are much less than for genes in this green alga. In contrast with human lncRNAs of which more than 98% are spliced, the percentage in C. reinhardtii is only 48.1%. In addition, we identified 367 lncRNAs responsive to sulfur deprivation, including 36 photosynthesis-related lncRNAs. This is the first time that lncRNAs were explored in the unicellular model organism C. reinhardtii. The lncRNA data could also provide new insights into C. reinhardtii hydrogen production under sulfur deprivation.
The conservative behavior of dissolved organic carbon in surface waters of the southern Chukchi Sea, Arctic Ocean, during early summer
Authors: Tanaka Kazuki , Takesue Nobuyuki , Nishioka Jun , Kondo Yoshiko , Ooki Atsushi , Kuma Kenshi , Hirawake Toru , Yamashita Youhei
Published: September 2016

The spatial distribution of dissolved organic carbon (DOC) concentrations and the optical properties of dissolved organic matter (DOM) determined by ultraviolet-visible absorbance and fluorescence spectroscopy were measured in surface waters of the southern Chukchi Sea, western Arctic Ocean, during the early summer of 2013. Neither the DOC concentration nor the optical parameters of the DOM correlated with salinity. Principal component analysis using the DOM optical parameters clearly separated the DOM sources. A significant linear relationship was evident between the DOC and the principal component score for specific water masses, indicating that a high DOC level was related to a terrigenous source, whereas a low DOC level was related to a marine source. Relationships between the DOC and the principal component scores of the surface waters of the southern Chukchi Sea implied that the major factor controlling the distribution of DOC concentrations was the mixing of plural water masses rather than local production and degradation.
Supramolecular anion recognition by β-HCH
Authors: Rednic Monica I. , Varga Richard A. , Bende Attila , Grosu Ioana G. , Miclăuş Maria , Hădade Niculina D. , Terec Anamaria , Bogdan Elena , Grosu Ion
Published: September 2016

Exciting β-HCH–anion recognition via cooperative aliphatic C–H–anion contacts is discussed.
Mechanistic insights into sodium storage in hard carbon anodes using local structure probes
Authors: Stratford Joshua M. , Allan Phoebe K. , Pecher Oliver , Chater Philip A. , Grey Clare P.
Published: September 2016

Hard carbon anodes for sodium-ion batteries are probed using solid state NMR and pair distribution function analysis.
Predictive methods for computational metalloenzyme redesign – a test case with carboxypeptidase A
Authors: Valdez Crystal E. , Morgenstern Amanda , Eberhart Mark E. , Alexandrova Anastassia N.
Published: September 2016

Computational metalloenzyme design is a multi-scale problem.
Infrared and fluorescence assessment of the hydration status of the tryptophan gate in the influenza A M2 proton channel
Authors: Markiewicz Beatrice N. , Lemmin Thomas , Zhang Wenkai , Ahmed Ismail A. , Jo Hyunil , Fiorin Giacomo , Troxler Thomas , DeGrado William F. , Gai Feng
Published: September 2016

The Trp41 tetrad of the M2 proton channel is found to be relatively dehydrated even at pH 5, indicative of the existence of an additional barrier for proton conduction.
Mobility and association of ions in aqueous solutions: the case of imidazolium based ionic liquids
Authors: Bešter-Rogač Marija , Fedotova Marina V. , Kruchinin Sergey E. , Klähn Marco
Published: September 2016

Combining MD simulations and RISM calculations with experiments, we demonstrated that the interionic interactions of investigated ILs as model 1,1 electrolytes in water solutions are weak but evidently dependent on the molecular structure.
Ruthenium-catalyzed hydroformylation: from laboratory to continuous miniplant scale
Authors: Kämper Alexander , Kucmierczyk Peter , Seidensticker Thomas , Vorholt Andreas J. , Franke Robert , Behr Arno
Published: September 2016

Ruthenium running its rounds – recycling of a homogeneous ruthenium catalyst for hydroformylation of linear aliphatic alkenes by ex situ product extraction and successful application in a continuously operated miniplant for 90 h.
Dopamine polymerization promoted by a catecholase biomimetic CuII(μ-OH)CuII complex containing a triazine-based ligand
Authors: de Oliveira José A. F. , da Silva Marcos P. , de Souza Bernardo , Camargo Tiago P. , Szpoganicz Bruno , Neves Ademir , Bortoluzzi Adailton J.
Published: September 2016

The catecholase-like catalytic activity and dopamine polymerization by using the dinuclear [LCuII(μ-OH)2CuII](ClO4)2 (1) complex are here described.
Bacterial components are the major contributors to the macrophage stimulating activity exhibited by extracts of common edible mushrooms
Authors: Tyler Heather L. , Haron Mona H. , Pugh Nirmal D. , Zhang Jin , Jackson Colin R. , Pasco David S.
Published: September 2016

Bacterial communities associated with edible mushrooms are the principal source of components responsible for thein vitroactivation of macrophages.
Universal microfluidic platform for bioassays in anchored droplets
Authors: Amselem Gabriel , Guermonprez Cyprien , Drogue Benoît , Michelin Sébastien , Baroud Charles N.
Published: September 2016

We describe a universal, user-friendly and robust microfluidic platform for bacterial culture that provides the parallel, time-resolved monitoring abilities of multiwell plates and selection of phenotypes of interest.
Amaryllidaceae and Sceletium alkaloids
Authors: Jin Zhong
Published: September 2016

The latest progress on the isolation, identification, biological activity and synthetic studies of the structurally diverse alkaloids from plants of family Amaryllidaceae has been summarized in this review.
TiO2–SiO2 Janus particles with highly enhanced photocatalytic activity
Authors: Panwar Kamlesh , Jassal Manjeet , Agrawal Ashwini K.
Published: September 2016

TiO2–SiO2 Janus particles, prepared by a Pickering emulsion method and calcined at 450 °C, due to their unique morphology and electronic structure showed highly enhanced photocatalytic activity.
Comment on “The size and structure of selected hydrated ions and implications for ion channel selectivity” by Z.-H. Yang, RSC. Adv., 2015,5, 1213.
Authors: Zavitsas Andreas A.
Published: September 2016

Hydration numbers of electrolytes from freezing point depressions plottedversusthe entropic contributions for the gaseous cations dissolving in water.
Biodegradable polymeric nanostructures in therapeutic applications: opportunities and challenges
Authors: Shukla S. K. , Shukla Sudheesh K. , Govender Penny P. , Giri N. G.
Published: September 2016

Biodegradable polymeric nanostructures (BPNs) have shown great promise in different therapeutic applications such as diagnosis, imaging, drug delivery, cosmetics, organ implants, and tissue engineering.
The epoxidation of canola oil and its derivatives
Authors: Omonov Tolibjon S. , Kharraz Ereddad , Curtis Jonathan M.
Published: September 2016

This work explores the epoxidation and subsequent acid catalyzed epoxy ring opening kinetics of canola oil (CanO), canola oil fatty acid methyl esters (CanFAME) and canola oil free fatty acids (CanFFA).
A visualized method for Cu2+ ion detection by self-assembling azide functionalized free graphene oxide using click chemistry
Authors: Tu Qin , Zhao Lei , Han Xiang , Wang Dong-En , Yuan Mao-Sen , Tian Chang , Wang Jinyi
Published: September 2016

We report a visualized method for the detection of Cu2+ ions by self-assembling azide functionalized graphene oxide using click chemistry.
Nano-curcumin influences blue light photodynamic therapy for restraining glioblastoma stem cells growth
Authors: Dev A. , Srivastava A. K. , Choudhury S. Roy , Karmakar S.
Published: September 2016

Nano-curcumin based blue light photodynamic therapy has therapeutic potential in the arsenal of glioblastoma cancer stem cells recurrence.
Aerobic oxidations in flow: opportunities for the fine chemicals and pharmaceuticals industries
Authors: Gavriilidis Asterios , Constantinou Achilleas , Hellgardt Klaus , Hii King Kuok (Mimi) , Hutchings Graham J. , Brett Gemma L. , Kuhn Simon , Marsden Stephen P.
Published: September 2016

This collaborative review (between teams of chemists and chemical engineers) describes the current scientific and operational hurdles that prevent the utilisation of aerobic oxidation reactions for the production of speciality chemicals and active pharmaceutical ingredients (APIs).
Preparation and characterization of Sm and Ca co-doped ceria–La0.6Sr0.4Co0.2Fe0.8O3−δsemiconductor–ionic composites for electrolyte-layer-free fuel cells
Authors: Wang Baoyuan , Wang Yi , Fan Liangdong , Cai Yixiao , Xia Chen , Liu Yanyan , Raza Rizwan , van Aken Peter A. , Wang Hao , zhu Bin
Published: September 2016

The oxygen enrichment at the interface leads to ionic conductivity enhancement for LSCF–SCDC composites, thus increasing the output of assembled EFFCs.
Ab initio prediction of a silicene and graphene heterostructure as an anode material for Li- and Na-ion batteries
Authors: Shi L. , Zhao T. S. , Xu A. , Xu J. B.
Published: September 2016

The heterostructure of silicene and graphene can serve as a promising anode material for lithium- and sodium-ion batteries.
Automated Proposition Density Analysis for Discourse in Aphasia
Authors: Fromm Davida , Greenhouse Joel , Hou Kaiyue , Russell G. Austin , Cai Xizhen , Forbes Margaret , Holland Audrey , MacWhinney Brian
Published: September 2016

Purpose

This study evaluates how proposition density can differentiate between persons with aphasia (PWA) and individuals in a control group, as well as among subtypes of aphasia, on the basis of procedural discourse and personal narratives collected from large samples of participants.

Method

Participants were 195 PWA and 168 individuals in a control group from the AphasiaBank database. PWA represented 6 aphasia types on the basis of the Western Aphasia Battery–Revised (Kertesz, 2006). Narrative samples were stroke stories for PWA and illness or injury stories for individuals in the control group. Procedural samples were from the peanut-butter-and-jelly-sandwich task. Language samples were transcribed using Codes for the Human Analysis of Transcripts (MacWhinney, 2000) and analyzed using Computerized Language Analysis (MacWhinney, 2000), which automatically computes proposition density (PD) using rules developed for automatic PD measurement by the Computerized Propositional Idea Density Rater program (Brown, Snodgrass, & Covington, 2007; Covington, 2007).

Results

Participants in the control group scored significantly higher than PWA on both tasks. PD scores were significantly different among the aphasia types for both tasks. Pairwise comparisons for both discourse tasks revealed that PD scores for the Broca's group were significantly lower than those for all groups except Transcortical Motor. No significant quadratic or linear association between PD and severity was found.

Conclusion

Proposition density is differentially sensitive to aphasia type and most clearly differentiates individuals with Broca's aphasia from the other groups.
Robotic AFO to enhance walking capacity: initial development
Authors: Mazumder O. , Kundu A. , Lenka P. , Bhaumik S.
Published: September 2016

The development of an active ankle foot orthosis (AFO) to enhance the walking capacity is presented. The proposed device consists of a linear actuator mechanism with supportive brace and is controlled by measuring user's interaction force. Initial experimental characterisation of performance of the control system and system usability tested on healthy individuals are reported. Results indicate a decrease in muscle activation, by a factor of 29 and 26% for plantar flexion and dorsiflexion motion while walking with assistance from the developed AFO. The developed system has potential application in the field of assistive technology for geriatrics or for patient with mobility impairments, muscle weakness or as a performance enhancer.
Electromagnetic interference of wireless power transfer system on wearable electrocardiogram
Authors: Liao Wei , Shi Jingjing , Wang Jianqing
Published: September 2016

The increasing ageing population is leading to a wide‐scale demand for health‐state monitoring by a wireless body area network (BAN). Wireless BAN needs each vital sensor to act as a wearable device for collecting blood pressure, electrocardiogram (ECG), electroencephalogram and so on in daily life. On the other hand, wireless power transfer is also getting into our daily life because of its convenience, which suggests a potential electromagnetic interference (EMI) problem on the wearable devices in healthcare and medical BAN. In this study, the authors quantitatively evaluated the EMI on wearable ECG for 6.8 MHz wireless power transfer system. They employed electromagnetic field analysis technique to derive the common‐mode voltage between the human body with a wearable ECG and the ground plane, and circuit simulation or measurement to derive the interference voltage at the wearable ECG output. The result first time gave a quantitative evaluation for EMI of wireless power transfer on wearable ECG. The approach is also available to be applied to EMI evaluation of other wearable devices in healthcare or medical applications.
Experimental analysis of buoyancy battery energy storage system
Authors: Bassett Kyle , Carriveau Rupp , Ting David S.‐K.
Published: September 2016

Buoyancy battery underwater energy storage is an emerging area of research relating to the storage of energy generated by renewable resources such as offshore wind and solar. This study presents an experimental analysis of a basic buoyancy system. Tests were performed on a container with minimal ambient fluid volume, as well as in a large offshore testing tank. Development and integration of fundamental system components is discussed in terms of experimental apparatus and larger application. Discharge cycling was performed with variables relating to discharge voltage, power, and discharge velocity obtained. Energy losses to kinetic energy and hydrodynamic drag are estimated for completed trails. The effect of pulley friction is evaluated for no‐load discharge testing. Conclusions are drawn as to the observed operation of the system as designed, primary areas for performance improvements, and next steps for system development.
Fracture of perfect and defective graphene at the nanometer scale: Is graphene the strongest material?
Authors: Hess Peter
Published: September 2016

The basic relationships between the linear elastic and nonlinear fracture properties given by a local bond-breaking model and Griffith's criterion are used to characterize the two-dimensional (2D) mechanical properties of an intrinsic and a defective graphene, respectively. The analytical 2D models describe the localized bond-breaking in perfect monolayers and the failure of defective graphene by the global energy balance concept. From the experimental data, density functional theory calculations, molecular dynamics simulations, and continuum 2D models, a consistent set of 2D mechanical properties consisting of Young's modulus, fracture strength, fracture toughness, line (edge) energy, and critical strain energy release rate can be obtained. The critical fracture stress shows a linear dependence on the square root of the effective defect length from the subnanometer to the micrometer scale. The lower limit of fracture toughness and strain energy release rate is essentially independent of the defect size for vacancies, slits, and pre-cracks in the nanometer range. In the subnanometer range, the direct bond breaking and Griffith models deliver a consistent description of mode I fracture by a uniaxial tension. The promising results suggest an extension of the continuum models to other fracture modes such as the failure by shear load.
Atomic level insights into realistic molecular models of dendrimer-drug complexes through MD simulations
Authors: Jain Vaibhav , Maiti Prabal K. , Bharatam Prasad V.
Published: September 2016

Computational studies performed on dendrimer-drug complexes usually consider 1:1 stoichiometry, which is far from reality, since in experiments more number of drug molecules get encapsulated inside a dendrimer. In the present study, molecular dynamic (MD) simulations were implemented to characterize the more realistic molecular models of dendrimer-drug complexes (1:n stoichiometry) in order to understand the effect of high drug loading on the structural properties and also to unveil the atomistic level details. For this purpose, possible inclusion complexes of model drug Nateglinide (Ntg) (antidiabetic, belongs to Biopharmaceutics Classification System class II) with amine- and acetyl-terminated G4 poly(amidoamine) (G4 PAMAM(NH2) and G4 PAMAM(Ac)) dendrimers at neutral and low pH conditions are explored in this work. MD simulation analysis on dendrimer-drug complexes revealed that the drug encapsulation efficiency of G4 PAMAM(NH2) and G4 PAMAM(Ac) dendrimers at neutral pH was 6 and 5, respectively, while at low pH it was 12 and 13, respectively. Center-of-mass distance analysis showed that most of the drug molecules are located in the interior hydrophobic pockets of G4 PAMAM(NH2) at both the pH; while in the case of G4 PAMAM(Ac), most of them are distributed near to the surface at neutral pH and in the interior hydrophobic pockets at low pH. Structural properties such as radius of gyration, shape, radial density distribution, and solvent accessible surface area of dendrimer-drug complexes were also assessed and compared with that of the drug unloaded dendrimers. Further, binding energy calculations using molecular mechanics Poisson–Boltzmann surface area approach revealed that the location of drug molecules in the dendrimer is not the decisive factor for the higher and lower binding affinity of the complex, but the charged state of dendrimer and drug, intermolecular interactions, pH-induced conformational changes, and surface groups of dendrimer do play an important role in the stabilization of complex. Interestingly, it was observed from the equilibrated structures of dendrimer-drug complexes at low pH that encapsulated drug molecules in the G4 PAMAM(NH2) formed cluster, while in the case of nontoxic G4 PAMAM(Ac) they were uniformly distributed inside the dendritic cavities. Thus, the latter dendrimer is suggested to be suitable nanovehicle for the delivery of Ntg. This computational analysis highlighted the importance of realistic molecular models of dendrimer-drug complexes (1:n) in order to obtain reliable results.
Photoluminescence studies in epitaxial CZTSe thin films
Authors: Sendler Jan , Thevenin Maxime , Werner Florian , Redinger Alex , Li Shuyi , Hägglund Carl , Platzer-Björkman Charlotte , Siebentritt Susanne
Published: September 2016

Epitaxial Cu2ZnSnSe4 (CZTSe) thin films were grown by molecular beam epitaxy on GaAs(001) using two different growth processes, one containing an in-situ annealing stage as used for solar cell absorbers and one for which this step was omitted. Photoluminescences (PL) measurements carried out on these samples show no dependence of the emission shape on the excitation intensity at different temperatures ranging from 4 K to 300 K. To describe the PL measurements, we employ a model with fluctuating band edges in which the density of states of the resulting tail states does not seem to depend on the excited charge carrier density. In this interpretation, the PL measurements show that the annealing stage removes a defect level, which is present in the samples without this annealing.
Chlorine measurement in the jet singlet oxygen generator considering the effects of the droplets
Authors: Goodarzi Mohamad S. , Saghafifar Hossein
Published: September 2016

A new method is presented to measure chlorine concentration more accurately than conventional method in exhaust gases of a jet-type singlet oxygen generator. One problem in this measurement is the existence of micrometer-sized droplets. In this article, an empirical method is reported to eliminate the effects of the droplets. Two wavelengths from a fiber coupled LED are adopted and the measurement is made on both selected wavelengths. Chlorine is measured by the two-wavelength more accurately than the one-wavelength method by eliminating the droplet term in the equations. This method is validated without the basic hydrogen peroxide injection in the reactor. In this case, a pressure meter value in the diagnostic cell is compared with the optically calculated pressure, which is obtained by the one-wavelength and the two-wavelength methods. It is found that chlorine measurement by the two-wavelength method and pressure meter is nearly the same, while the one-wavelength method has a significant error due to the droplets.
Mechanical properties of hydrogenated electron-irradiated graphene
Authors: Weerasinghe Asanka , Muniz Andre R. , Ramasubramaniam Ashwin , Maroudas Dimitrios
Published: September 2016

We report a systematic analysis on the effects of hydrogenation on the mechanical behavior of irradiated single-layer graphene sheets, including irradiation-induced amorphous graphene, based on molecular-dynamics simulations of uniaxial tensile straining tests and using an experimentally validated model of electron-irradiated graphene. We find that hydrogenation has a significant effect on the tensile strength of the irradiated sheets only if it changes the hybridization of the hydrogenated carbon atoms to sp3, causing a reduction in the strength of irradiation-induced amorphous graphene by ∼10 GPa. Hydrogenation also causes a substantial decrease in the failure strain of the defective sheets, regardless of the hybridization of the hydrogenated carbon atoms, and in their fracture toughness, which decreases with increasing hydrogenation for a given irradiation dose. We characterize in detail the fracture mechanisms of the hydrogenated irradiated graphene sheets and elucidate the role of hydrogen and the extent of hydrogenation in the deformation and fracture processes. Our study sets the stage for designing hydrogenation and other chemical functionalization strategies toward tailoring the properties of defect-engineered ductile graphene.
Darboux transformations with tetrahedral reduction group and related integrable systems
Authors: Berkeley George , Mikhailov Alexander V. , Xenitidis Pavlos
Published: September 2016

In this paper, we derive new two-component integrable differential difference and partial difference systems by applying a Lax-Darboux scheme to an operator formed from an 𝔰𝔩3(ℂ)-based automorphic Lie algebra. The integrability of the found systems is demonstrated via Lax pairs and generalised symmetries.
Chimera states in networks of Van der Pol oscillators with hierarchical connectivities
Authors: Ulonska Stefan , Omelchenko Iryna , Zakharova Anna , Schöll Eckehard
Published: September 2016

Chimera states are complex spatio-temporal patterns that consist of coexisting domains of coherent and incoherent dynamics. We analyse chimera states in ring networks of Van der Pol oscillators with hierarchical coupling topology. We investigate the stepwise transition from a nonlocal to a hierarchical topology and propose the network clustering coefficient as a measure to establish a link between the existence of chimera states and the compactness of the initial base pattern of a hierarchical topology; we show that a large clustering coefficient promotes the occurrence of chimeras. Depending on the level of hierarchy and base pattern, we obtain chimera states with different numbers of incoherent domains. We investigate the chimera regimes as a function of coupling strength and nonlinearity parameter of the individual oscillators. The analysis of a network with larger base pattern resulting in larger clustering coefficient reveals two different types of chimera states and highlights the increasing role of amplitude dynamics.
Interactions between magnetic nanoparticles and model lipid bilayers—Fourier transformed infrared spectroscopy (FTIR) studies of the molecular basis of nanotoxicity
Authors: Kręcisz M. , Rybka J. D. , Strugała A. J. , Skalski B. , Figlerowicz M. , Kozak M. , Giersig M.
Published: September 2016

The toxicity of nanoparticles (nanotoxicity) is often associated with their interruption of biological membranes. The effect of polymer-coated magnetic nanoparticles (with different Fe3O4 core sizes and different polymeric coatings) on a model biological membrane system of vesicles formed by dimyristoylphosphatidylcholine (DMPC) was studied. Selected magnetic nanoparticles with core sizes ranging from 3 to 13 nm (in diameter) were characterised by transmission electron microscopy. Samples with 10% DMPC and different nanoparticle concentrations were studied by attenuated total reflectance—Fourier transform infrared spectroscopy to establish the influence of nanoparticles on the phase behaviour of model phospholipid systems.
Addressing optimal underwater electrical explosion of a wire
Authors: Virozub A. , Gurovich V. Tz. , Yanuka D. , Antonov O. , Krasik Ya. E.
Published: September 2016

The underwater electrical explosion of a wire in the timescale 10−7–10−6 s is characterized by different phase transitions at extreme values of deposited energy density, allowing one to obtain warm dense matter using rather moderate pulse power generators. In order to achieve maximal energy density deposition, the parameters of the wire and the pulse generator should be optimized to realize an overdamped explosion where most of the initially stored energy is delivered to the exploding wire during a time comparable with the quarter of the discharge period. In this paper, the results of 1D magneto-hydrodynamic modeling, coupled with the copper and water equations of state, of the underwater electrical explosion of Cu wires having an identical length and average current density but different discharge current rise time are analyzed and compared with those of a simplified model of a conductivity wave, the propagation velocity of which determines the mode of the wire's explosion. In addition, it is shown that in the case of extreme high current densities, a scaling from a single wire to a wire array having the same total cross-sectional area of wires cannot be used to obtain an optimal wire explosion.
Communication: The formation of rarefaction waves in semiconductors after ultrashort excitation probed by grazing incidence ultrafast time-resolved x-ray diffraction
Authors: Höfer S. , Kämpfer T. , Förster E. , Stöhlker T. , Uschmann I.
Published: September 2016

We explore the InSb-semiconductor lattice dynamics after excitation of high density electron-hole plasma with an ultrashort and intense laser pulse. By using time resolved x-ray diffraction, a sub-mÅ and sub-ps resolution was achieved. Thus, a strain of 4% was measured in a 3 nm thin surface layer 2 ps after excitation. The lattice strain was observed for the first 5 ps as exponentially decaying, changing rapidly by time and by depth. The observed phenomena can only be understood assuming nonlinear time dependent laser absorption where the absorption depth decreases by a factor of twenty compared to linear absorption.
Simultaneous use of Cs and Rb Rydberg atoms for dipole moment assessment and RF electric field measurements via electromagnetically induced transparency
Authors: Simons Matt T. , Gordon Joshua A. , Holloway Christopher L.
Published: September 2016

We demonstrate simultaneous electromagnetically-induced transparency (EIT) with cesium (Cs) and rubidium (Rb) Rydberg atoms in the same vapor cell with coincident (overlapping) optical fields. Each atomic system can detect radio frequency (RF) electric (E) field strengths through the modification of the EIT signal (Autler-Townes (AT) splitting), which leads to a direct International System of Unit traceable RF E-field measurement. We show that these two systems can detect the same RF E-field strength simultaneously, which provides a direct in situ comparison of Rb and Cs RF measurements in Rydberg atoms. In effect, this allows us to perform two measurements of the same E-field strength, providing a relative comparison of the dipole moments of the two atomic species. This gives two measurements that help rule out systematic effects and uncertainties in this E-field metrology approach, which are important when establishing an international measurement standard for an E-field strength, and is a necessary step for this method to be accepted as a standard calibration technique. We use this approach to measure E-fields at 9.2 GHz, 11.6 GHz, and 13.4 GHz, which correspond to three different atomic states (different principal atomic numbers and angular momentums) for the two atom species.
Spatially resolved density and ionization measurements of shocked foams using x-ray fluorescence
Authors: MacDonald M. J. , Keiter P. A. , Montgomery D. S. , Scott H. A. , Biener M. M. , Fein J. R. , Fournier K. B. , Gamboa E. J. , Kemp G. E. , Klein S. R. , Kuranz C. C. , LeFevre H. J. , Manuel M. J.-E. , Wan W. C. , Drake R. P.
Published: September 2016

We present experiments at the Trident laser facility demonstrating the use of x-ray fluorescence (XRF) to simultaneously measure density, ionization state populations, and electron temperature in shocked foams. An imaging x-ray spectrometer obtained spatially resolved measurements of Ti K-α emission. Density profiles were measured from K-α intensity. Ti ionization state distributions and electron temperatures were inferred by fitting K-α spectra to spectra from CRETIN simulations. This work shows that XRF provides a powerful tool to complement other diagnostics to make equation of state measurements of shocked materials containing a suitable tracer element.
Current dependence of colossal anisotropic magnetoresistance in La0.3Pr0.4Ca0.3MnO3 microbridges
Authors: Jeon J. , Jung J. , Chow K. H.
Published: September 2016

The effect of the bias current on the in-plane colossal anisotropic magnetoresistance (C-AMR) is investigated in spatially confined La0.3Pr0.4Ca0.3MnO3 microbridges. Dramatic increases of the C-AMR are found when the bias current is reduced. For example, in one of the samples, the C-AMR changed from ∼900% to over ∼24 000% as the current is decreased from 1 μA to 10 nA. The results indicate that the bias current can be used to manipulate the C-AMR in spatially confined manganite thin films via changes to the nature of the anisotropic percolation within the samples.
Determination of relative krypton fission product yields from 14 MeV neutron induced fission of 238U at the National Ignition Facility
Authors: Edwards E. R. , Cassata W. S. , Velsko C. A. , Yeamans C. B. , Shaughnessy D. A.
Published: September 2016

Precisely-known fission yield distributions are needed to determine a fissioning isotope and the incident neutron energy in nuclear security applications. 14 MeV neutrons from DT fusion at the National Ignition Facility induce fission in depleted uranium contained in the target assembly hohlraum. The fission yields of Kr isotopes (85m, 87, 88, and 89) are measured relative to the cumulative yield of 88Kr and compared to previously tabulated values. The results from this experiment and England and Rider are in agreement, except for the 85mKr/88Kr ratio, which may be the result of incorrect nuclear data.
Continuous ultrathin silver films deposited on SiO2 and SiNx using a self-assembled monolayer
Authors: Hafezian Soroush , Maloney Kate , Lefebvre Josianne , Martinu Ludvik , Kéna-Cohen Stéphane
Published: September 2016

In this letter, we study the deposition of ultrathin silver films on silicon oxide and nitride surfaces functionalized with self-assembled monolayers of (3-mercaptopropyl)-trimethoxysilane. First, we compare both solution and vapour-phase functionalization techniques and find the greatest improvement in electrical and optical properties using deposition from solution. Using X-ray photoelectron spectroscopy, we demonstrate that the formation of silver-sulfur covalent bonds is at the root of the improved wetting confirmed by ellipsometry, sheet resistance measurement, and atomic force microscopy. Second, we show that this technique can be extended to functionalize silicon nitride. Finally, we demonstrate a simple, but efficient, low-emissivity optical filter.
Trap behaviours characterization of AlGaN/GaN high electron mobility transistors by room-temperature transient capacitance measurement
Authors: Dong Bin , Lin Jie , Wang Ning , Jiang Ling-li , Liu Zong-dai , Hu Xiaoyan , Cheng Kai , Yu Hong-yu
Published: September 2016

In this paper, the trap behaviours in AlGaN/GaN high electron mobility transistors (HEMTs) are investigated using transient capacitance measurement. By measuring the transient gate capacitance variance (ΔC) with different pulse height, the gate pulse induced trap behaviours in SiNX gate dielectric layer or at the SiNX/AlGaN interface is revealed. Based on the results, a model on electron traps in AlGaN/GaN HEMTs is proposed. The threshold voltage (Vth) instability in AlGaN/GaN HEMTs is believed to be correlated with the presence of these traps in SiNX gate dielectric layer or at the SiNX/AlGaN interface. Furthermore, trap density before and after step-stress applied on drain electrode is quantitatively analyzed based on ΔC measurement.
Numerical analysis of quench in coated conductors with defects
Authors: Liu Wenbin , Yong Huadong , Zhou Youhe
Published: September 2016

When the superconductor is subjected to local thermal perturbations, a large amount of joule heat may be generated in the conductor, which may lead to a quench. In a quench event, a normal zone irreversibly spreads throughout the conductor leading to failure of the superconducting device. In this paper, we will discuss the one-dimensional quench behavior in the coated conductors with internal defects or interface defects. Based on the numerical procedure given in the previous works, the normal zone propagation is studied by using the finite difference method. The numerical results are presented to discuss the normal zone propagation. We consider the effect of internal defect on the nonuniform temperature propagation. For the conductor with interface defects, it can be found that the normal zone propagation velocity is increased by defects.
Frequent handling of grazing beef cattle maintained under the rotational stocking method improves temperament over time
Authors: Ceballos Maria C. , Góis Karen Camille R. , Sant'Anna Aline C. , Paranhos da Costa Mateus J. R.
Published: September 2016

Our aims were to assess the effects of handling frequency on temperament evolution in cattle kept under rotational stocking method (RSM), as well as to compare the temperament of animals maintained under rotational versus alternate stocking (ASM) methods. We evaluated 4256 males raised on pasture from four private properties (Farms 1–4), for a total of 9628 observations. The study was divided into two complementary approaches. In the first one, monthly visits were conducted at 35-day intervals to assess the cattle temperament (n = 1979) raised on grazing system using RSM, while, in the second approach, we evaluated the temperament of cattle (n = 3600) kept under two different stocking methods, namely, (1) RSM (n = 2007), characterised by a high frequency of animal handling and a 4-day grazing period, and (2) ASM (n = 1593), characterised by a low frequency of handling and a 20-day grazing period. Composite reactivity score (RS), and flight speed (FS) were considered as temperament indicators. Reductions of RS and FS means were observed during successive assessments under RSM. Significant effects of stocking method on FS (P < 0.05) and RS (P < 0.01) were found, with lower FS and RS means for animals under RSM than for those under ASM. In conclusion, the frequent handling in the rotational stocking method favoured the improvement of cattle temperament over time, with lower levels of reactivity among cattle raised under this stocking method than with animals raised under the alternate stocking method.