bluuebunny/crossref_metadata_2025 huggingface dataset:
A chemical biology toolbox to study protein methyltransferases and epigenetic signaling
Authors: Scheer Sebastian , Ackloo Suzanne , Medina Tiago S. , Schapira Matthieu , Li Fengling , Ward Jennifer A. , Lewis Andrew M. , Northrop Jeffrey P. , Richardson Paul L. , Kaniskan H. Ümit , Shen Yudao , Liu Jing , Smil David , McLeod David , Zepeda-Velazquez Carlos A. , Luo Minkui , Jin Jian , Barsyte-Lovejoy Dalia , Huber Kilian V. M. , De Carvalho Daniel D. , Vedadi Masoud , Zaph Colby , Brown Peter J. , Arrowsmith Cheryl H.
Published: December 2018

Protein methyltransferases (PMTs) comprise a major class of epigenetic regulatory enzymes with therapeutic relevance. Here we present a collection of chemical probes and associated reagents and data to elucidate the function of human and murine PMTs in cellular studies. Our collection provides inhibitors and antagonists that together modulate most of the key regulatory methylation marks on histones H3 and H4, providing an important resource for modulating cellular epigenomes. We describe a comprehensive and comparative characterization of the probe collection with respect to their potency, selectivity, and mode of inhibition. We demonstrate the utility of this collection in CD4+ T cell differentiation assays revealing the potential of individual probes to alter multiple T cell subpopulations which may have implications for T cell-mediated processes such as inflammation and immuno-oncology. In particular, we demonstrate a role for DOT1L in limiting Th1 cell differentiation and maintaining lineage integrity. This chemical probe collection and associated data form a resource for the study of methylation-mediated signaling in epigenetics, inflammation and beyond.
Crystal structures of the human neurokinin 1 receptor in complex with clinically used antagonists
Authors: Schöppe Jendrik , Ehrenmann Janosch , Klenk Christoph , Rucktooa Prakash , Schütz Marco , Doré Andrew S. , Plückthun Andreas
Published: December 2018

Neurokinins (or tachykinins) are peptides that modulate a wide variety of human physiology through the neurokinin G protein-coupled receptor family, implicated in a diverse array of pathological processes. Here we report high-resolution crystal structures of the human NK1receptor (NK1R) bound to two small-molecule antagonist therapeutics – aprepitant and netupitant and the progenitor antagonist CP-99,994. The structures reveal the detailed interactions between clinically approved antagonists and NK1R, which induce a distinct receptor conformation resulting in an interhelical hydrogen-bond network that cross-links the extracellular ends of helices V and VI. Furthermore, the high-resolution details of NK1R bound to netupitant establish a structural rationale for the lack of basal activity in NK1R. Taken together, these co-structures provide a comprehensive structural basis of NK1R antagonism and will facilitate the design of new therapeutics targeting the neurokinin receptor family.
Dissociable cognitive strategies for sensorimotor learning
Authors: McDougle Samuel D. , Taylor Jordan A.
Published: December 2018

Computations underlying cognitive strategies in human motor learning are poorly understood. Here we investigate such strategies in a common sensorimotor transformation task. We show that strategies assume two forms, likely reflecting distinct working memory representations: discrete caching of stimulus-response contingencies, and time-consuming parametric computations. Reaction times and errors suggest that both strategies are employed during learning, and trade off based on task complexity. Experiments using pressured preparation time further support dissociable strategies: In response caching, time pressure elicits multi-modal distributions of movements; during parametric computations, time pressure elicits a shifting distribution of movements between visual targets and distal goals, consistent with analog re-computing of a movement plan. A generalization experiment reveals that discrete and parametric strategies produce, respectively, more localized or more global transfer effects. These results describe how qualitatively distinct cognitive representations are leveraged for motor learning and produce downstream consequences for behavioral flexibility.
A region-resolved mucosa proteome of the human stomach
Authors: Ni Xiaotian , Tan Zhaoli , Ding Chen , Zhang Chunchao , Song Lan , Yang Shuai , Liu Mingwei , Jia Ru , Zhao Chuanhua , Song Lei , Liu Wanlin , Zhou Quan , Gong Tongqing , Li Xianju , Tai Yanhong , Zhu Weimin , Shi Tieliu , Wang Yi , Xu Jianming , Zhen Bei , Qin Jun
Published: December 2018

The human gastric mucosa is the most active layer of the stomach wall, involved in food digestion, metabolic processes and gastric carcinogenesis. Anatomically, the human stomach is divided into seven regions, but the protein basis for cellular specialization is not well understood. Here we present a global analysis of protein profiles of 82 apparently normal mucosa samples obtained from living individuals by endoscopic stomach biopsy. We identify 6,258 high-confidence proteins and estimate the ranges of protein expression in the seven stomach regions, presenting a region-resolved proteome reference map of the near normal, human stomach. Furthermore, we measure mucosa protein profiles of tumor and tumor nearby tissues (TNT) from 58 gastric cancer patients, enabling comparisons between tumor, TNT, and normal tissue. These datasets provide a rich resource for the gastrointestinal tract research community to investigate the molecular basis for region-specific functions in mucosa physiology and pathology including gastric cancer.
Acto-myosin force organization modulates centriole separation and PLK4 recruitment to ensure centriole fidelity
Authors: Vitiello Elisa , Moreau Philippe , Nunes Vanessa , Mettouchi Amel , Maiato Helder , Ferreira Jorge G. , Wang Irène , Balland Martial
Published: December 2018

The presence of aberrant number of centrioles is a recognized cause of aneuploidy and hallmark of cancer. Hence, centriole duplication needs to be tightly regulated. It has been proposed that centriole separation limits centrosome duplication. The mechanism driving centriole separation is poorly understood and little is known on how this is linked to centriole duplication. Here, we propose that actin-generated forces regulate centriole separation. By imposing geometric constraints via micropatterns, we were able to prove that precise acto-myosin force arrangements control direction, distance and time of centriole separation. Accordingly, inhibition of acto-myosin contractility impairs centriole separation. Alongside, we observed that organization of acto-myosin force modulates specifically the length of S-G2 phases of the cell cycle, PLK4 recruitment at the centrosome and centriole fidelity. These discoveries led us to suggest that acto-myosin forces might act in fundamental mechanisms of aneuploidy prevention.
The conformational changes coupling ATP hydrolysis and translocation in a bacterial DnaB helicase
Authors: Wiegand Thomas , Cadalbert Riccardo , Lacabanne Denis , Timmins Joanna , Terradot Laurent , Böckmann Anja , Meier Beat H.
Published: December 2018

DnaB helicases are motor proteins that couple ATP-hydrolysis to the loading of the protein onto DNA at the replication fork and to translocation along DNA to separate double-stranded DNA into single strands during replication. Using a network of conformational states, arrested by nucleotide mimics, we herein characterize the reaction coordinates for ATP hydrolysis, DNA loading and DNA translocation using solid-state NMR spectroscopy. AMP-PCP is used as pre-hydrolytic, ADP:AlF4− as transition state, and ADP as post-hydrolytic ATP mimic. 31P and 13C NMR spectra reveal conformational and dynamic responses to ATP hydrolysis and the resulting DNA loading and translocation with single amino-acid resolution. This allows us to identify residues guiding the DNA translocation process and to explain the high binding affinities for DNA observed for ADP:AlF4−, which turns out to be optimally preconfigured to bind DNA.
pH effects on the electrochemical reduction of CO(2) towards C2 products on stepped copper
Authors: Liu Xinyan , Schlexer Philomena , Xiao Jianping , Ji Yongfei , Wang Lei , Sandberg Robert B. , Tang Michael , Brown Kristopher S. , Peng Hongjie , Ringe Stefan , Hahn Christopher , Jaramillo Thomas F. , Nørskov Jens K. , Chan Karen
Published: December 2018

We present a microkinetic model for CO(2) reduction (CO(2)R) on Cu(211) towards C2 products, based on energetics estimated from an explicit solvent model. We show that the differences in both Tafel slopes and pH dependence for C1 vs C2 activity arise from differences in their multi-step mechanisms. We find the depletion in C2 products observed at high overpotential and high pH to arise from the 2nd order dependence of C-C coupling on CO coverage, which decreases due to competition from the C1 pathway. We further demonstrate that CO(2) reduction at a fixed pH yield similar activities, due to the facile kinetics for CO2 reduction to CO on Cu, which suggests C2 products to be favored for CO2R under alkaline conditions. The mechanistic insights of this work elucidate how reaction conditions can lead to significant enhancements in selectivity and activity towards higher value C2 products.
Uncovering electron scattering mechanisms in NiFeCoCrMn derived concentrated solid solution and high entropy alloys
Authors: Mu Sai , Samolyuk German D. , Wimmer Sebastian , Troparevsky Maria C. , Khan Suffian N. , Mankovsky Sergiy , Ebert Hubert , Stocks George M.
Published: December 2018

Whilst it has long been known that disorder profoundly affects transport properties, recent measurements on a series of solid solution 3d-transition metal alloys reveal two orders of magnitude variations in the residual resistivity. Using ab initio methods, we demonstrate that, while the carrier density of all alloys is as high as in normal metals, the electron mean-free-path can vary from ~10 Å (strong scattering limit) to ~103 Å (weak scattering limit). Here, we delineate the underlying electron scattering mechanisms responsible for this disparate behavior. While site-diagonal, spin dependent, potential scattering is always dominant, for alloys containing only Fe, Co, and Ni the majority-spin channel experiences negligible disorder scattering, thereby providing a short circuit, while for Cr/Mn containing alloys both spin channels experience strong disorder scattering due to an electron filling effect. Somewhat surprisingly, other scattering mechanisms—including displacement, or size effect, scattering which has been shown to strongly correlate with such diverse properties as yield strength—are found to be relatively weak in most cases.
Strain engineering of electro-optic constants in ferroelectric materials
Authors: Paillard Charles , Prokhorenko Sergei , Bellaiche Laurent
Published: December 2018

Electro-optic effects allow control of the ow of light using electric fields, and are of utmost importance for today’s information and communication technologies, such as TV displays and fiber optics. The search for large electro-optic constants in films is essential to the miniaturization and increased efficiency of electro-optic devices. In this work, we demonstrate that strain-engineering in PbTiO3 films allows to selectively choose which electro-optic constant to improve. Unclamped electro-optic constants larger than 100 pm V−1 are predicted, either by driving the softening of an optical phonon mode at a phase transition boundary under tensile strain, or by generating the equivalent of a negative pressure via compressive strain to obtain large piezoelectric constants. In particular, a r13 electro-optic coefficient twice as large as the one of the commonly used LiNbO3 electro-optic material is found here when growing PbTiO3 on the technologicallyimportant Si substrate.
Learning to predict single-wall carbon nanotube-recognition DNA sequences
Authors: Yang Yoona , Zheng Ming , Jagota Anand
Published: December 2018

DNA/single-wall carbon nanotube (SWCNT) hybrids have enabled many applications because of their special ability to disperse and sort SWCNTs by their chirality and handedness. Much work has been done to discover sequences which recognize specific chiralities of SWCNT, and significant progress has been made in understanding the underlying structure and thermodynamics of these hybrids. Nevertheless, de novo prediction of recognition sequences remains essentially impossible and the success rate for their discovery by search of the vast single-stranded DNA library is very low. Here, we report an effective way of predicting recognition sequences based on machine learning analysis of existing experimental sequence data sets. Multiple input feature construction methods (position-specific, term-frequency, combined or segmented term frequency vector, and motif-based feature) were used and compared. The transformed features were used to train several classifier algorithms (logistic regression, support vector machine, and artificial neural network). Trained models were used to predict new sets of recognition sequences, and consensus among a number of models was used successfully to counteract the limited size of the data set. Predictions were tested using aqueous two-phase separation. New data thus acquired were used to retrain the models by adding an experimentally tested new set of predicted sequences to the original set. The frequency of finding correct recognition sequences by the trained model increased to >50% from the ~10% success rate in the original training data set.
Comparison of Bacillus subtilis transcriptome profiles from two separate missions to the International Space Station
Authors: Morrison Michael D. , Fajardo-Cavazos Patricia , Nicholson Wayne L.
Published: December 2018

The human spaceflight environment is notable for the unique factor of microgravity, which exerts numerous physiologic effects on macroscopic organisms, but how this environment may affect single-celled microbes is less clear. In an effort to understand how the microbial transcriptome responds to the unique environment of spaceflight, the model Gram-positive bacteriumBacillus subtiliswas flown on two separate missions to the International Space Station in experiments dubbed BRIC-21 and BRIC-23. Cells were grown to late-exponential/early stationary phase, frozen, then returned to Earth for RNA-seq analysis in parallel with matched ground control samples. A total of 91 genes were significantly differentially expressed in both experiments; 55 exhibiting higher transcript levels in flight samples and 36 showing higher transcript levels in ground control samples. Genes upregulated in flight samples notably included those involved in biofilm formation, biotin and arginine biosynthesis, siderophores, manganese transport, toxin production and resistance, and sporulation inhibition. Genes preferentially upregulated in ground control samples notably included those responding to oxygen limitation, e.g., fermentation, anaerobic respiration, subtilosin biosynthesis, and anaerobic regulatory genes. The results indicated differences in oxygen availability between flight and ground control samples, likely due to differences in cell sedimentation and the toroidal shape assumed by the liquid cultures in microgravity.
Insulin signaling in Drosophila melanogaster mediates Aβ toxicity
Authors: Huang Yunpeng , Wan Zhihui , Wang Zhiqing , Zhou Bing
Published: December 2018

Alzheimer’s disease (AD) and diabetes are clinically positively correlated. However, the connection between them is not clarified. Here, using Drosophila as a model system, we show that reducing insulin signaling can effectively suppress the toxicity from Aβ (Amyloid beta 42) expression. On the other hand, Aβ accumulation led to the elevation of fly insulin-like peptides (ILPs) and activation of insulin signaling in the brain. Mechanistically, these observations are attributed to a reciprocal competition between Drosophila insulin-like peptides and Aβ for the activity of insulin-degrading enzyme (IDE). Intriguingly, peripheral insulin signaling is decreased despite its heightened activity in the brain. While many upstream factors may modify Aβ toxicity, our results suggest that insulin signaling is the main downstream executor of Aβ damage, and thus may serve as a promising target for Alzheimer’s treatment in non-diabetes patients. This study explains why more Alzheimer’s cases are found in diabetes patients.
Enhanced electrochemical performance and high voltage window for supercapacitor based on multi-heteroatom modified porous carbon materials
Authors: Deng Yalei , Ji Yajun , Wu Hongmei , Chen Fei
Published: December 2018

Enhanced electrochemical performance and high voltage window for supercapacitor based on the multi-heteroatom modified porous carbon materials.
Single crystal structure and optical properties of nonlinear optical crystal Rb0.94Ti0.94Ta0.06OPO4
Authors: Li Ziqing , Zhu Pengfei , Chen Yang , Ji Nianjing , Liu Jian , Duan Xiulan , Jiang Huaidong
Published: December 2018

SHG efficiency of Rb0.94Ti0.94Ta0.06OPO4 is about 1.4 times that of RTP.
Nanoparticle aggregation in a freshwater river: the role of engineered surface coatings
Authors: Surette Mark C. , Nason Jeffrey A.
Published: December 2018

Surface coatings applied to ENPs alter eco-corona formation in complex aquatic matrices, affecting homo- and heteroaggregation processes and environmental fate.
Perylenetetracarboxy-3,4:9,10-diimide derivatives with large two-photon absorption activity
Authors: Garoni Eleonora , Nisic Filippo , Colombo Alessia , Fantacci Simona , Griffini Gianmarco , Kamada Kenji , Roberto Dominique , Dragonetti Claudia
Published: December 2018

Perylenetetracarboxy-3,4:9,10-diimides with large TPA cross-sections.
Base-promoted direct synthesis of functionalized N-arylindoles via the cascade reactions of allenic ketones with indoles
Authors: Li Shengxiao , Wu Xin-Xing , Chen Shufeng
Published: December 2018

A convenient base-promoted cascade benzannulation reaction of allenic ketones with indole derivatives has been established.
Quasi-monodisperse polymer libraries via flash column chromatography: correlating dispersity with glass transition
Authors: Haven Joris J. , Junkers Tanja
Published: December 2018

Quasi-monodisperse (Đ = 1.005–1.040) poly(methyl) acrylate (PMA) polymer libraries are obtained via flash column chromatography separation of disperse (Đ = 1.130) PMA. The influence of dispersity on the glass transition is investigated.
Thioalkyl- and sulfone-substituted poly(p-phenylene vinylene)s
Authors: Rimmele Martina , Ableidinger Klaus , Marsh Adam V. , Cheetham Nathan J. , Taublaender M. Josef , Buchner Alina , Prinz Jonathan , Fröhlich Johannes , Unterlass Miriam M. , Heeney Martin , Glöcklhofer Florian
Published: December 2018

Poly(p-phenylene vinylene)s (PPVs) have been studied for decades, but new applications like in bioimaging keep emerging and even simple structural variations are still waiting to be explored, as we highlight by this work.
Dual-source evaporation of silver bismuth iodide films for planar junction solar cells
Authors: Khazaee Maryam , Sardashti Kasra , Chung Ching-Chang , Sun Jon-Paul , Zhou Hanhan , Bergmann Eric , Dunlap-Shohl Wiley A. , Han Qiwei , Hill Ian G. , Jones Jacob L. , Lupascu Doru C. , Mitzi David B.
Published: December 2018

Dual-source evaporation approach is applied to deposit AgBi2I7, AgBiI4 and Ag2BiI5 films; a planar junction AgBiI4-solar cell is demonstrated.
Weiterbildung zum eHealth-Berater und Vernetzung im eHealthWerk
Authors: Kokelmann Christoph , Stumpf Paul
Published: December 2018

Die Digitalisierung im Gesundheitswesen ist aus gesundheitspolitischer wie wirtschaftlicher Sicht hochaktuell. Das technisch Machbare steht jedoch der Herausforderung gegenüber, dass sowohl Patienten als auch professionelle Gesundheitsakteure in der Anwendung entsprechend geschult sein müssen. Mitunter kann der Arzt diese Beratungsleistung jedoch gar nicht leisten, weil er selbst zu unerfahren ist. Damit steigt die Wahrscheinlichkeit, dass sich der Patient die eHealth-Tools eigenständig und unsystematisch zu erschließen versucht und dass das Selbstmanagement seiner Krankheit nachteilig beeinflusst wird. Die Weiterbildung zum eHealth-Berater greift diese Diskrepanz auf und fördert die digitale Gesundheitskompetenz der Gesundheitsakteure zielgerichtet. Die Evaluation der Pilotphase konnte bestätigen, dass das Konzept der Weiterbildung dieses Ziel erreicht. Ergänzt durch aktuelle Inhalte aus dem Online-Netzwerk sind die Teilnehmer optimal für die Digitalisierung im Gesundheitswesen gerüstet.
Möglichkeiten moderner Diabetestechnologie
Authors: Thomas Andreas
Published: December 2018

In Form von Spritzen und Kanülen zur Insulininjektion stehen den Patienten prinzipiell seit Beginn der Diabetestherapie technologische Anwendungen bereit. An dieser Situation änderte sich über viele Jahrzehnte wenig, bis in den 1980er-Jahren eine rasante Entwicklung einsetzte, welche die Diabetestherapie revolutionierte. Das betraf 2 grundsätzliche Bereiche: Einerseits standen Insulinpens und feinere Insulinkanülen zur Verfügung, dies förderte die Bereitschaft der Patienten für eine physiologischere, aber auch mehr Injektionen erforderlich machende Insulintherapie. Dazu gehören auch die zu dieser Zeit aufkommenden Insulinpumpen. Andererseits gelang es, kleine, transportable Blutzuckermessgeräte und Teststreifen mit vertretbar geringen notwendigen Blutmengen zur Messung bereitzustellen, was die Patienten in die Lage versetzte, ihre Therapie im Alltag selbst zu führen. Diese Entwicklung ist in den letzten Jahren immer rasanter geworden. Ein Meilenstein war das kontinuierliche Glukosemonitoring (CGM), ein wichtiger Bestandteil in Systemen für eine automatisierte Insulinabgabe und die Zusammenführung von Messung und Insulinabgabe. Weiterhin können durch die kontinuierliche Glukosemessung auch Blutzuckermessungen einschränkt bzw. ganz verzichtbar werden. Mit den Errungenschaften der modernen Informationstechnologie ergeben sich völlig neue Möglichkeiten, die unter den gebräuchlichen Begriff „Digitalisierung“ fallen. Wurde zunächst nur Software zur Analyse von Glukosewerten entwickelt, so lassen sich mittlerweile Daten auch über eine Cloud einem Computer zuführen, der sie analysiert und dem Patienten im Alltag unterstützende Verhaltenshinweise gibt (Patienten-Entscheidungs-Systeme). Die Möglichkeiten der modernen Diabetestechnologie betreffen nicht mehr nur Patienten mit Typ-1-, sondern zunehmend auch die mit Typ-2-Diabetes. Generell führt dies zu einem veränderten Verhältnis zwischen Arzt und Patient, wobei beide Seiten wirkungsvoll unterstützt werden.
Characteristics and Management of Patients with Venous Thromboembolism: The GARFIELD-VTE Registry
Authors: Ageno Walter , Haas Sylvia , Weitz Jeffrey I. , Goldhaber Samuel Z. , Turpie Alexander G. G. , Goto Shinya , Angchaisuksiri Pantep , Nielsen Joern Dalsgaard , Kayani Gloria , Pieper Karen S. , Schellong Sebastian , Bounameaux Henri , Mantovani Lorenzo G. , Prandoni Paolo , Kakkar Ajay K. ,   on behalf of the GARFIELD-VTE investigators
Published: December 2018

Background Management of venous thromboembolism (VTE), encompassing both deep vein thrombosis (DVT) and pulmonary embolism (PE), varies worldwide.

Methods The Global Anticoagulant Registry in the FIELD – Venous Thromboembolism (GARFIELD-VTE) is a prospective, observational study of 10,685 patients with objectively diagnosed VTE recruited from May 2014 to January 2017 at 417 sites in 28 countries. All patients are followed for at least 3 years. We describe the baseline characteristics of the study population and their management within 30 days of diagnosis.

Results The median age was 60.2 years; 50.4% were male; 61.7% had DVT and 38.3% had PE ± DVT; and 32.3% were obese (body mass index ≥ 30 kg/m2). The most common risk factors were surgery (12.5%), hospitalization (12.0%) and trauma to the lower limbs (7.8%). At the time of VTE diagnosis, 10.1% had active cancer and 5.7% were chronically immobilized. Treatment for VTE was anticoagulant (AC) therapy alone in 90.9% of patients; 5.1% received thrombolytic and/or surgical/mechanical therapy ± AC and 4.0% received no therapy. Pre-diagnosis, 12.8% received AC therapy alone and 0.2% received thrombolytic and/or surgical/mechanical therapy ± AC. After diagnosis, parenteral AC therapy alone was administered in 17.6% of patients, and it was followed by a direct oral AC (DOAC) in 16.4% or a vitamin K antagonist (VKA) in 26.8%. DOACs alone were prescribed to 32.3% of patients, while 5.9% received VKA alone.

Conclusion The initial findings from this global registry highlight the heterogeneity in characteristics and management of VTE patients. Prospective follow-up will reveal the impact of this heterogeneity on outcomes.
Updating a Perinatal Risk Scoring System to Predict Infant Mortality
Authors: Umer Amna , Lilly Christa , Hamilton Candice , Cottrell Lesley , Lefeber Timothy , Hulsey Thomas , John Collin
Published: December 2018

Objective The Birth Score Project (Project WATCH) began in the rural state of West Virginia (WV) in the United States in 1984. The project is intended to identify newborns with a greater risk of infant mortality. The primary objective of this study was to update the current Birth Score based on current literature and rigorous statistical methodology.

Study Design The study merged data from the Birth Score, Birth Certificate (birth years 2008–2013), and Infant Mortality Data (N = 121,640). The merged data were randomly divided into developmental (N = 85,148) and validation (N = 36,492) datasets. Risk scoring system was developed using the weighted multivariate risk score functions and consisted of infant and maternal factors.

Results The updated score ranged from 0 to 86. Infants with a score of ≥17 were categorized into the high score group (n = 15,387; 18.1%). The odds of infant mortality were 5.6 times higher (95% confidence interval: 4.4, 7.1) among those who had a high score versus low score.

Conclusion The updated score is a better predictor of infant mortality than the current Birth Score. This score has practical relevance for physicians in WV to identify newborns at the greatest risk of infant mortality and refer the infants to primary pediatric services and case management for close follow-up.
Passive Ceiling Light Disinfection System to Reduce Bioburden in an Intensive Care Unit
Authors: Rohan Annie , Khan Imraan , Yin Donglei , Yang Jie
Published: December 2018

A ceiling-installed narrow spectrum (402–420 nm) bactericidal blue light disinfection system was installed in a large suburban medical intensive care unit (ICU) and evaluated for implementation feasibility and effectiveness in reducing environmental bioburden. Installation of 54 ceiling devices was accomplished at low cost and with minimal ICU process disruption. Postinstallation high-touch surface colony counts were significantly lower than preinstallation. Linear mixed modeling demonstrated a 21% average overall decrease in colony count after installation, with consistent reduction in colony counts starting from week 4 postinstallation. Automated technology is potentially more efficient in reducing environmental bioburden in the acute care setting compared with other bioburden reducing methods or can provide a robust compliment to manual cleaning.
An autonomous optimal control strategy for reducing Gaussian laser beam constraint effect on photovoltaic array
Authors: Zhang Rui , Wang Yibo , Xu Honghua
Published: December 2018

A novel autonomous optimal control strategy on a photovoltaic array under a Gaussian beam constraint condition for a high-intensity laser power beaming system is proposed in this paper. The proposed strategy divides the PV array into several concentric parallel branches according to Gaussian irradiance distribution and optimizes the series and parallel forms of each concentric branch and its PV cells, which is not dependent on the specific PV array topology and can obtain an optimal connection form matching with the system under Gaussian beam constraint condition. The proposed strategy can be applied to the different connection forms of PV array for minimizing the Gaussian constraint effect by utilizing the characteristics of Gaussian irradiance distribution on laser facula and the inherent error values in the matching area of the laser facula and the PV array, and the output power and the efficiency of PV array can reach an optimal value simultaneously. The uneven irradiance of Gaussian laser facula is mathematically modeled in this paper. The correctness of theoretical analysis is verified by simulation results.
Realization of uniform transverse gain in an edge-pumped multislab pulsed amplifier with a gradient profile doping
Authors: Li Min , Yan Xiongwei , Feng Xi , Tang Xuan , Wang Jianjun , Li Mingzhong , Zhang Xiaomin
Published: December 2018

Gradient doping ensures uniform transverse gain in an edge-pumped multislab pulsed amplifier, and a 1D iterative method is developed to generate the proper doping profile. Our investigations show that uniform gain under short pump duration tp = 0.25 ms can be readily achieved, where the modulation of the gain distribution is lower than 1.05 even if the diagonal transverse gain-length product (DTGLP) increases up to 5. For tp = 1.0 ms, comparable modulation of the gain distribution is achieved for a much lower DTGLP value of 2.3. To extend the DTGLP range for long pump duration, a modified 1D iterative method with an effectively “shortened” lifetime of the active ions is developed. With the modified method, the gain uniformity for both pumping conditions is greatly improved, and specifically, the DTGLP increases from 2.3 to 3.0 for tp = 1.0 ms. In addition, degradation of the gain uniformity resulting from deviations of the doping concentration is discussed. The deviations should be at least lower than 1% and 5% for tp = 1.0 ms and tp = 0.25 ms to maintain the gain uniformity, respectively. Our investigations might provide a useful way to design the amplifier with uniform gain in the beam aperture of a high average power pulsed laser.
Brightness of femtosecond nonequilibrium photoemission in metallic photocathodes at wavelengths near the photoemission threshold
Authors: Bae Jai Kwan , Bazarov Ivan , Musumeci Pietro , Karkare Siddharth , Padmore Howard , Maxson Jared
Published: December 2018

The operation of photoemission electron sources with wavelengths near the photoemission threshold has been shown to dramatically decrease the minimum achievable photocathode emittance, but at the cost of significantly reduced quantum efficiency (QE). In this work, we show that for femtosecond laser and electron pulses, the increase in required laser intensities due to the low QE drives the photocathode electronic distribution far from static equilibrium. We adapt an existing dynamic model of the electron occupation under high intensity laser illumination to predict the time-dependent effects of the nonequilibrium electron distribution on the QE, mean transverse energy (MTE), and emission brightness of metal photocathodes. We find that multiphoton photoemission dramatically alters the MTE as compared to thermal equilibrium models, causing the MTE to no longer be a monotonic function of photon excess energy.
Color-center formation and thermal recovery in X-ray and electron-irradiated magnesium aluminate spinel
Authors: Costantini Jean-Marc , Lelong Gérald , Guillaumet Maxime , Takaki Seiya , Yasuda Kazuhiro
Published: December 2018

We have studied the formation of color centers in magnesium aluminate spinel (MgAl2O4) by X-ray and electron irradiations near room temperature (RT). For this purpose, Cu Kα radiation and three electron energies (1.0, 1.4, and 2.5 MeV) were used for variable fluences (up to 4.2 × 1018 cm−2). Off-line UV-visible absorption spectra were recorded at RT as well as at low temperature down to 27 K after electron irradiation. The dependence of the production rate of F centers (oxygen vacancies) on the electron energy yields a threshold displacement energy of 190 ± 10 eV for oxygen atoms at RT, which is much higher than the determinations by molecular-dynamics simulations. Such a discrepancy is discussed on the basis of available migration data of point defects in spinel. Equipartition of F0 and F+ centers, i.e., the neutral (VOx) and singly ionized (VO.) oxygen vacancies, is reached for high electron fluences. Moreover, the evolution of the width of color-center absorption bands versus temperature is interpreted with the classical theory for F centers (neutral halogen vacancies) in alkali halides. The Stokes shifts are deduced from the temperature dependence of the absorption bandwidths of color centers like for alkali halides and alkaline-earth oxides. Finally, isothermal annealing data for long annealing time show a non-zero asymptotic behavior for both F0 and F+ centers. This uncommon behavior is interpreted by charge exchange processes leading to an equilibrium state between those two color centers.
Reduced order derivation of the two-dimensional band structure of a mixed-mode resonator array
Authors: Amirkhizi Alireza V. , Wang Weidi
Published: December 2018

In this paper, the 2D band structure of a mixed-mode metamaterial resonator array for in-plane waves is investigated. The band structure in the interior and on the boundary of the irreducible Brillouin zone and 1D dispersion diagrams for different propagation angles are calculated numerically and presented. Additionally, a reduced order analytical method is established to compare and approximate the band structure. The studied metamaterial, with a T-shaped cantilever beam as the resonator in its square array repeating unit cells, exhibits branches with mixed P and SV waves except at exactly one angle of propagation. This paper also reports on the occurrence of avoided level crossings, which are related to the existence of exceptional points in the complex domain. A reduced order analytical approach is used that can generate partial (low branches) band structure with relatively little computational effort. The reduced order model agrees well with the numerical results for these low branches and can provide support in mode identification and band sorting. With proper adjustments in parameters, this analytical method will be applicable to other metamaterials that have a similar unit cell structure.
Reflectance of a reflective photonic crystal p-contact layer for improving the light-extraction efficiency of AlGaN-based deep-ultraviolet light-emitting diodes
Authors: Yun Joosun , Kashima Yukio , Hirayama Hideki
Published: December 2018

We utilized the finite-difference time-domain method (FDTD) to investigate the reflectance of an air void photonic crystal (PhC) on the p-electrode of an AlGaN-based deep ultraviolet (DUV) light-emitting diode (LED). Firstly, a transparent p-AlGaN layer with cylindrical air voids on a Ni(1nm)/Al(140nm) metal electrode was optimized to maximize the reflectance at normal incidence. It was shown that by having the optimum AlGaN PhC on the metal electrode, the reflectance as a function of the angle of incidence was advantageously redistributed to increase LEE. The calculated angle-dependent reflectances were converted to average reflectance considering the power distribution of dipole sources in the TE and TM modes. The average reflectances of a reference structure and the PhC structure for the TM mode at wavelengths around 283 nm were 77.1 and 85.2%, respectively. Thus, an incremental increase of 8% in average reflectance for the TM mode was obtained by adopting the optimized PhC. Secondly, we investigated a PhC with air voids in two different layers, a p-GaN layer and a p-AlGaN layer on the Ni/Al. The calculated average reflectances at 283 nm were 38% and 42% for the TE and TM modes, respectively, when the thickness of the p-GaN layer was 70 nm. The average reflectances for the TE and TM modes with a uniform 70nm thick p-GaN layer without a PhC were 4.2 and 3.6%, respectively. This clearly shows that the optimized PhC can reduce light absorption in both the p-GaN layer and the metal electrode.
Achieving higher thermoelectric performance for p-type Cr2Ge2Te6 via optimizing doping
Authors: Tang Xiaodan , Fan Dengdong , Guo Lijie , Tan Huan , Wang Shuxia , Lu Xu , Cao Xianlong , Wang Guoyu , Zhou Xiaoyuan
Published: December 2018

Cr2Ge2Te6-based compounds with a layered structure and high symmetry hold a great promise for thermoelectric applications. Our studies have been committed to improve their electrical properties considering the low power factor of only ∼0.23 mW/mK2 in pristine samples. In this work, various doping contents on the site that has less influence on the charge-conducting band have been investigated to enhance the power factor. The results show that Fe-doping is the most favorable among elements we applied. According to the first-principles calculation, the Fe doping on the Cr site leads to the increment of the density of states around the Fermi level. By tuning the carrier concentration via Fe doping, the peak power factor rises from 0.23 mW/mK2 to 0.37 mW/mK2 and zT rises from 0.3 to 0.4 at 830 K for Cr1.9Fe0.1Ge2Te6 along the pressing direction. These results shed lights for designing high performance thermoelectric materials.
Microstructure and properties of as-cast 30Mn steel
Authors: Yan H. H. , Hu Y. , Zhao D. W.
Published: December 2018

The microstructure and properties of as-cast 30Mn steel with and without adding rare earths were systematically investigated. The microstructure was characterized by optical microscopy and scanning electron microscopy combined with energy-dispersive spectroscopy. The addition of rare earths could improve the cast structure. The austenitic transformation of the two steels was studied by differential scanning calorimetry. The onset and finish temperature of austenite increased, and the relative content of ferrites and pearlites changed. Rare earths, when added, improved the strength and plasticity, and increase the impact toughness by 31.3%. The heat deformation behavior was analyzed by using a Gleeble-3500 thermo-mechanical simulator. The onset of dynamic recrystallization was delayed, and the hot deformation microstructures were refined.
Overlimiting current due to electro-diffusive amplification of the second Wien effect at a cation-anion bipolar membrane junction
Authors: Schiffbauer Jarrod , Ganchenko Nataly Yu. , Ganchenko Georgy S. , Demekhin Evgeny A.
Published: December 2018

Numerical simulations are presented for the transient and steady-state response of a model electrodiffusive cell with a bipolar ion-selective membrane under electric current. The model uses a continuum Poisson-Nernst-Planck theory including source terms to account for the catalytic second Wien effect between ionogenic groups in the membranes and resolves the Debye layers at interfaces. The resulting electric field at the membrane junction is increased by as much as four orders of magnitude in comparison to the field external to the membrane. This leads to a significant amplification of the second Wien effect, creating an increased ionic flux due to the catalytic decomposition of water. The effect also induces an exaltation effect wherein the salt ion flux undergoes a concomitant increase as well. The interplay of effects results in a unique over-limiting current mechanism due to concentration polarization internal, rather than external, to the membranes. In addition to the case of two equal but oppositely charged membranes under the standard simplifying assumption of equal ionic diffusivities, two variations on this model are studied. Asymmetric diffusivities, representative of the actual mobility difference in dissociated water ions, and the effect of the membrane charge density ratio were also considered. The latter elucidates an overlimiting current shift mechanism for DNA adsorption on anion-selective membranes proposed by Slouka et al. [Langmuir 29, 8275 (2013)]. The former provides more realistic picture of multi-ion transport and demonstrates a surprising steady-state effect due to the asymmetry in the diffusivity of hydroxide and hydronium.
Determination of the rheological properties of Matrigel for optimum seeding conditions in microfluidic cell cultures
Authors: Kane K. I. W. , Lucumi Moreno E. , Lehr C. M. , Hachi S. , Dannert R. , Sanctuary R. , Wagner C. , Fleming R. M. T. , Baller J.
Published: December 2018

Hydrogels are increasingly used as a surrogate extracellular matrix in three-dimensional cell culture systems, including microfluidic cell culture. Matrigel is a hydrogel of natural origin widely used in cell culture, particularly in the culture of stem cell-derived cell lines. The use of Matrigel as a surrogate extracellular matrix in microfluidic systems is challenging due to its biochemical, biophysical, and biomechanical properties. Therefore, understanding and characterising these properties is a prerequisite for optimal use of Matrigel in microfluidic systems. We used rheological measurements and particle image velocimetry to characterise the fluid flow dynamics of liquefied Matrigel during loading into a three-dimensional microfluidic cell culture device. Using fluorescence microscopy and fluorescent beads for particle image velocimetry measurements (velocity profiles) in combination with classical rheological measurements of Matrigel (viscosity versus shear rate), we characterised the shear rates experienced by cells in a microfluidic device for three-dimensional cell culture. This study provides a better understanding of the mechanical stress experienced by cells, during seeding of a mixture of hydrogel and cells, into three-dimensional microfluidic cell culture devices.
Strong emission of THz radiation from GaAs microstructures on Si
Authors: Maeng Inhee , Lee Gyuseok , Kang Chul , Ju Gun Wu , Park Kwangwook , Son Seoung-Bum , Lee Yong-Tak , Kee Chul-Sik
Published: December 2018

Remarkably strong emission of terahertz radiation from illuminated GaAs microstructures on a Si substrate is reported. The peak–to–peak amplitude of terahertz radiation from the sample is 9 times larger than that of THz radiation from a semi-insulating GaAs wafer. The spectral width of the sample is larger than that of a semi-insulating GaAs wafer; in particular, the spectral amplitude increases at higher frequencies. The presented GaAs microstructures on a Si substrate can be suitable for practical and efficient THz sources required in various THz applications.
Numerical study on solidification heat transfer of spherical composite phase change capsule with high thermal conductivity
Authors: Dai Xiaoli , Wu Xiaoyan , Tian Fei
Published: December 2018

This study explores numerically the solidification of a spherical composite phase change capsule (PCC) with high thermal conductivity, in which expanded graphite (EG) is added into the high-density polyethylene (HDPE)/paraffin shape-stabilized phase change material (SSPCM). The mathematical model is solved numerically by the apparent heat capacity method. In the simulations, the volume change of paraffin during phase transformation and the distribution of cavities arising from the manufacturing process are considered. As an important thermophysical property of the HDPE/paraffin/EG material, the effective thermal conductivity is determined based on fractal theory, the laws of minimal thermal resistance and specific equivalent thermal conductivity. The model is validated by comparison with similar available models and the agreement is found to be satisfactory. The influence of several significant parameters on the heat transfer process is analyzed, such as the content of EG, volume change of the PCM, etc. The results show that the volume change of paraffin has a great impact on the heat transfer process during the later stages. A certain amount of EG addition can effectively improve the heat transfer characteristics of the phase change capsule, including the moving rate of the phase interface and instantaneous release rate of heat flux.
Simple and fast determination of band structure and level repulsion in a mixed-mode metamaterial
Authors: Cockbill Louisa
Published: December 2018

Advanced treatment of a reduced order model is shown to agree well with numerical results in a complex mixed-mode resonator array.
Geometrically incompatible confinement of solids
Authors: Davidovitch Benny , Sun Yiwei , Grason Gregory M.
Published: December 2018

Significance

The complex morphologies of confined skins (e.g., a candy wrapper or a wrinkled elbow) emerge from the generic conflict between their susceptibility to buckling even under minute compression and the unavoidable strain in conforming geometries. Our study of the implications of this conflict leads to the formulation of an effective principle—the Gauss–Euler
elastica
—that characterizes the feasible deformations of thin sheets subject to “geometrically incompatible confinement.”
Comparison of small extracellular vesicles isolated from plasma by ultracentrifugation or size‐exclusion chromatography: yield, purity and functional potential
Authors: Takov Kaloyan , Yellon Derek M. , Davidson Sean M.
Published: December 2018

Interest in small extracellular vesicles (sEVs) as functional carriers of proteins and nucleic acids is growing continuously. There are large numbers of sEVs in the blood, but lack of standardised methods for sEV isolation greatly limits our ability to study them. In this report, we use rat plasma to systematically compare two commonly used techniques for isolation of sEVs: ultracentrifugation (UC‐sEVs) and size‐exclusion chromatography (SEC‐sEVs). SEC‐sEVs had higher particle number, protein content, particle/protein ratios and sEV marker signal than UC‐sEVs. However, SEC‐sEVs also contained greater amounts of APOB+ lipoproteins and large quantities of non‐sEV protein. sEV marker signal correlated very well with both particle number and protein content in UC‐sEVs but not in all of the SEC‐sEV fractions. Functionally, both UC‐sEVs and SEC‐sEVs isolates contained a variety of proangiogenic factors (with endothelin‐1 being the most abundant) and stimulated migration of endothelial cells. However, there was no evident correlation between the promigratory potential and the quantity of sEVs added, indicating that non‐vesicular co‐isolates may contribute to the promigratory effects. Overall, our findings suggest that UC provides plasma sEVs of lower yields, but markedly higher purity compared to SEC. Furthermore, we show that the functional activity of sEVs can depend on the isolation method used and does not solely reflect the sEV quantity. These findings are of importance when working with sEVs isolated from plasma‐ or serum‐containing conditioned medium.
Facile sonochemical synthesis of artichoke-like Co3O4-graphene nanocomposites
Authors: Kamar E M , El-Dek S I
Published: December 2018

Facile sonochemical technique was used for the first time to synthesize Co3O4-graphene nanocomposites at room temperature. The nanocomposites under investigation were prepared with different Co3O4 molar ratios of nanoparticles. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Fourier transform infrared spectroscopy (FT-IR) and UV-vis spectroscopy. The results show that Co3O4 nanoparticles were distributed uniformly on the surface of graphene sheet. This work reports a simple preparation approach and recommends the described methodology for the decoration of graphene sheet surface with miscellaneous metal oxide nanoparticles.