bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemical exchange saturation transfer fingerprinting for exchange rate quantification
Authors: Zhou Zhengwei , Han Pei , Zhou Bill , Christodoulou Anthony G. , Shaw Jaime L. , Deng Zixin , Li Debiao
Published: May 2018

Purpose

There is an increased interest to determine the exchange rate using CEST to provide pH information. However, current CEST quantification methods require lengthy scan times and do not address magnetization transfer effects. The purpose of this work was to apply the magnetic resonance fingerprinting (MRF) concept to CEST to achieve more efficient and accurate exchange rate quantification.

Methods

The proposed CEST fingerprinting method used varying saturation powers and saturation times to create unique signal evolutions for different exchange rates. The acquired signal was matched to a predefined dictionary to determine the exchange rate. The magnetization transfer effects were also addressed in the framework of CEST fingerprinting: The simulated dictionary could predict the signal curves without magnetization transfer effects, and comparing the dictionary to the acquired signals allowed the correction of the magnetization transfer effects. The CEST fingerprinting method was compared with the conventional pulsed quantitative CEST method using omega plots in the creatine phantom study.

Results

The CEST fingerprinting method has a significantly reduced scan time (10 minutes versus 50 minutes) while providing more accurate exchange rate quantification using literature values as the reference.

Conclusion

In this study, we demonstrate that CEST fingerprinting is more efficient (5 times faster) compared with pulsed quantitative CEST. It is also shown that the results of the proposed CEST fingerprinting technique are much closer to the literature values than pulsed quantitative CEST at 3 T.
Breast magnetic resonance elastography: a review of clinical work and future perspectives
Authors: Bohte A.E. , Nelissen J.L. , Runge J.H. , Holub O. , Lambert S.A. , de Graaf L. , Kolkman S. , van der Meij S. , Stoker J. , Strijkers G.J. , Nederveen A.J. , Sinkus R.
Published: May 2018

This review on magnetic resonance elastography (MRE) of the breast provides an overview of available literature and describes current developments in the field of breast MRE, including new transducer technology for data acquisition and multi‐frequency‐derived power‐law behaviour of tissue. Moreover, we discuss the future potential of breast MRE, which goes beyond its original application as an additional tool in differentiating benign from malignant breast lesions. These areas of ongoing and future research include MRE for pre‐operative tumour delineation, staging, monitoring and predicting response to treatment, as well as prediction of the metastatic potential of primary tumours.
Diffusional kurtosis imaging and white matter microstructure modeling in a clinical study of major depressive disorder
Authors: Kamiya Kouhei , Okada Naohiro , Sawada Kingo , Watanabe Yusuke , Irie Ryusuke , Hanaoka Shouhei , Suzuki Yuichi , Koike Shinsuke , Mori Harushi , Kunimatsu Akira , Hori Masaaki , Aoki Shigeki , Kasai Kiyoto , Abe Osamu
Published: May 2018

Major depressive disorder (MDD) is a globally prevalent psychiatric disorder that results from disruption of multiple neural circuits involved in emotional regulation. Although previous studies using diffusion tensor imaging (DTI) found smaller values of fractional anisotropy (FA) in the white matter, predominantly in the frontal lobe, of patients with MDD, studies using diffusion kurtosis imaging (DKI) are scarce. Here, we used DKI whole‐brain analysis with tract‐based spatial statistics (TBSS) to investigate the brain microstructural abnormalities in MDD. Twenty‐six patients with MDD and 42 age‐ and sex‐matched control subjects were enrolled. To investigate the microstructural pathology underlying the observations in DKI, a compartment model analysis was conducted focusing on the corpus callosum. In TBSS, the patients with MDD showed significantly smaller values of FA in the genu and frontal portion of the body of the corpus callosum. The patients also had smaller values of mean kurtosis (MK) and radial kurtosis (RK), but MK and RK abnormalities were distributed more widely compared with FA, predominantly in the frontal lobe but also in the parietal, occipital, and temporal lobes. Within the callosum, the regions with smaller MK and RK were located more posteriorly than the region with smaller FA. Model analysis suggested significantly smaller values of intra‐neurite signal fraction in the body of the callosum and greater fiber dispersion in the genu, which were compatible with the existing literature of white matter pathology in MDD. Our results show that DKI is capable of demonstrating microstructural alterations in the brains of patients with MDD that cannot be fully depicted by conventional DTI. Though the issues of model validation and parameter estimation still remain, it is suggested that diffusion MRI combined with a biophysical model is a promising approach for investigation of the pathophysiology of MDD.
Failure Mode, Effect, and Criticality Analysis of the Parenteral Nutrition Process in a Mother–Child Hospital: The AMELIORE Study
Authors: Boulé Marianne , Lachapelle Sophie , Collin‐Lévesque Laurence , Demers Émile , Nguyen Christina , Fournier‐Tondreau Marylou , Thibault Maxime , Lebel Denis , Bussières Jean‐François
Published: May 2018

Background

The parenteral nutrition (PN) process is complex and involves multiple steps and substeps, especially in pediatrics and neonatology, given the particular needs of these patients. The objective of this study was to perform a critical analysis of the PN process at the Centre Hospitalier Universitaire Sainte‐Justine to determine which potential pitfalls are related to this process and which should be prioritized when implementing corrective measures.

Methods

This is a Failure Mode, Effect, and Criticality Analysis (FMECA) study. A multidisciplinary team assessed each step of the PN process and identified associated failure modes. Adapted rating scales were used to determine severity, frequency, and detectability of the failure modes. Ratings were established through multidisplinary consensus, and a criticality index (CI) was calculated for each failure mode.

Results

A total of 265 failure modes were identified in the 5 major steps of the PN process. The failure mode with the highest CI was the inscription of an inaccurate weight at prescription, with a CI of 800. The step with the highest cumulative CIs was administration to patients, with a CI sum of 7691. Various recommendations aimed at minimizing the risks associated with the PN process were made following this FMECA. Additional interventions are expected to emanate from this project because data will be presented throughout the departments involved.

Conclusion

This study is a successful example for other hospitals interested in carrying out the same kind of healthcare improvement initiative.
A qualitative study of assistant nurses' experiences of palliative care in residential care
Authors: Udo Camilla , Neljesjö Maria , Strömkvist Ingegerd , Elf Marie
Published: May 2018

Aim

To explore assistant nurses' experiences and perceptions of both positive and negative aspects of providing palliative care for older people in residential care facilities.

Design

A qualitative explorative study.

Methods

Critical incidents were collected through semi‐structured face‐to‐face interviews and analysed by performing a qualitative content analysis.

Results

A total of 40 critical incidents from daily work was described by assistant nurses. The results showed that close cooperation between unlicensed and licensed professionals was crucial to provide good care but was sometimes negatively affected by the organizational structure. The availability of professionals was identified as a critical factor in providing good care at the end of life in a consultative organization. The most prominent findings were those that indicated that, especially in a consultative organization, there seems to be a need for clear roles, comprehensive and clear care plans and a solid support structure to ensure continuity of care.
Chromogenic and Fluorogenic Probes for the Detection of Illicit Drugs
Authors: Garrido Eva , Pla Luis , Lozano‐Torres Beatriz , El Sayed Sameh , Martínez‐Máñez Ramón , Sancenón Félix
Published: May 2018

The consumption of illicit drugs has increased exponentially in recent years and has become a problem that worries both governments and international institutions. The rapid emergence of new compounds, their easy access, the low levels at which these substances are able to produce an effect, and their short time of permanence in the organism make it necessary to develop highly rapid, easy, sensitive, and selective methods for their detection. Currently, the most widely used methods for drug detection are based on techniques that require large measurement times, the use of sophisticated equipment, and qualified personnel. Chromo‐ and fluorogenic methods are an alternative to those classical procedures.
Synthesis and Application of Dendritic Fibrous Nanosilica/Gold Hybrid Nanomaterials
Authors: Byoun Wongyun , Jung Soeun , Tran Ngoc Minh , Yoo Hyojong
Published: May 2018

Morphologically unique silica nanoparticles can be used as effective templates to prepare silica–metal hybrid nanomaterials, which are highly applicable in a variety of areas. Mesoporous silica nanoparticles, which have high surface areas and an abundance of pores, can be used to synthesize mesoporous silica core–metal shell nanostructures with catalytically active sites. In this work, dendritic fibrous nanosilica (DFNS) with a high surface area is successfully employed as a template to synthesize DFNS/Au hybrid nanomaterials. Au nanodots are initially synthesized through the selective reduction of Au ions on the surface of the DFNS after surface modification to form DFNS/Au dots. A seed‐mediated growth method is used to controllably grow Au nanoparticles on the DFNS/Au dots to generate DFNS core–Au nanoparticles shell nanohybrids (DFNS/Au NPs) and DFNS core–Au layer shell nanohybrids (DFNS/Au layers). The catalytic activities of DFNS/Au NPs and DFNS/Au layers in the 4‐nitrophenol reduction reaction are compared.
Observers' response to facial disfigurement from head and neck cancer
Authors: Cho Joowon , Fingeret Michelle Cororve , Huang Sheng‐Cheng , Liu Jun , Reece Gregory P. , Markey Mia K.
Published: May 2018

Objective

Our long‐term goal is to develop a normative feedback intervention to support head and neck cancer patients in forming realistic expectations about how other people in non‐social group settings will respond to their appearance. This study aimed to evaluate the relationship between observer ratings of facial disfigurement and observer ratings of emotional response when viewing photographs of faces of head and neck cancer patients.

Methods

Seventy‐five (75) observers rated their emotional response to each of 144 facial photographs of head and neck cancer patients using the Self‐Assessment‐Manikin and rated severity of facial disfigurement on a 9‐point scale. Body image investment of the observers was measured using the Appearance Schemas Inventory‐Revised. A standardized multiple regression model was used to assess the relationship between observer ratings of facial disfigurement and observer ratings of emotional response, taking into consideration the age and sex of the patient depicted in the stimulus photograph, as well as the age, sex, and body image investment of the observer.

Results

Observers who had a strong emotional response to a patient's facial photograph tended to rate the patient's facial disfigurement as more severe (standardized regression coefficient β = 0.328, P < 0.001). Sex and age of the observer had more influence on the rating of facial disfigurement than did the patient's demographic characteristics. Observers more invested in their own body image tended to rate the facial disfigurement as more severe.

Conclusions

This study lays the groundwork for a normative database of emotional response to facial disfigurement.
Dihydrazinium Nitrates Derived from Malonic and Iminodiacetic Acid
Authors: Klapötke Thomas M. , Krumm Burkhard , Reith Thomas
Published: May 2018

Several hydrazinium nitrates were synthesized on the basis of malonic acid and iminodiacetic acid. The reaction of the corresponding ethyl esters with hydrazine hydrate yielded the dihydrazides in good‐to‐high yields and high purity. Subsequent protonation with diluted nitric acid or hydrochloric acid resulted in the corresponding nitrate and chloride salts. The neutral compounds and their salts were fully characterized, including multinuclear NMR spectroscopy, vibrational analysis, X‐ray diffraction, differential thermal analysis and elemental analysis. The energies of formation were calculated with the Gaussian program package and the detonation parameters were predicted using the Explo5 computer code.
Development and evaluation of cationic amphiphilic antimicrobial 2,5‐diketopiperazines
Authors: Labrière Christophe , Kondori Nahid , Caous Josefin Seth , Boomgaren Marc , Sandholm Kerstin , Ekdahl Kristina N. , Hansen Jørn H. , Svenson Johan
Published: May 2018

Both pathogenic bacteria and fungi are developing resistance to common antimicrobial treatment at an alarming rate. To counteract this development, it is of essence to develop new classes of antimicrobial agents. One such class is antimicrobial peptides, most of which are derived from the innate immune system. In this study, a series of novel 2,5‐diketopiperazines were designed, synthesized, and evaluated for their antimicrobial abilities. The compounds were designed to probe the pharmacophore dictated for short linear mimics of antimicrobial cationic peptides, and as such, the compounds contain a range of cationic and hydrophobic functionalities. Several of the prepared compounds displayed high antimicrobial activities toward bacteria and also against human pathogenic fungi. Of particular interest was the high activity toward fungal strains with an inherent increased resistance toward conventional antifungal agents. The most effective compounds displayed inhibition of Candida glabrata and Candida krusei growth at concentrations between 4 and 8 μg/mL, which is comparable to commercial antifungal agents in use. Structure activity relationship studies revealed a similar dependence on cationic charge and the volume of the hydrophobic bulk as for linear cationic antimicrobial peptides. Finally, the hemolytic activity of selected compounds was evaluated, which revealed a potential to produce active compounds with attenuation of unwanted hemolysis. The findings highlight the potential of cyclic cationic amphiphilic peptidomimetics as a class of promising compounds for the treatment of infections caused by microorganisms with an increased resistance to conventional antimicrobial agents.
Tunable Photocatalytic Properties of GaN‐Based Two‐Dimensional Heterostructures
Authors: Wang Guang‐Zhao , Dang Sui‐Hu , Zhao Wen‐Xi , Li Ya‐Dong , Xiao Shu‐Yuan , Zhong Ming‐Min
Published: May 2018

We have modulated the photocatalytic properties of GaN‐based two‐dimensional (2D) heterostructures including GaN/MoSe2 and GaN/WS2 (WSe2) by adjusting biaxial strain and the pH of electrolyte. The structural, energetic, and electronic properties of these GaN‐based heterostructures are investigated through hybrid density functional calculations so as to give the varied bandgaps and band edge positions. When the pH values are respectively within the scope of 7.2–7.9, 5.6–8 (9.2–10.6), and 11.2–12.4 (12.7–13), the suitable bandgaps and band edges make GaN/MoSe2, GaN/WS2, and GaN/WSe2 heterostructures sensitive to visible light and thermodynamically feasible for overall water redox processes. These results give a potential scheme for GaN‐based visible light photocatalysts.
Optimal design for resilient load‐sharing systems with nonidentical components
Authors: Xu Huyang , Fang Yuanchen , Fard Nasser
Published: May 2018

For system maintenance, strategic component restoration planning is an important conceptual framework for load‐sharing k‐out‐of‐n: G system. A cost‐effective treatment of failure events is imperative with the purpose of reinstating the system ability. This paper presents a new optimal design method for load‐sharing repairable k‐out‐of‐n: G system, in which a flowgraph is used in conjunction with multiresponse optimization. By introducing the concept of modular design, the system is partitioned into scalable and repairable maintenance modules. The determination of the optimal design depends on the type of system components, the module‐based system structure, and the repair rule setting. An extended flowgraph model, which links covariates into transition branches, is used for modeling the system failure evolution. With consideration of various system performance measurements as responses, multiresponse optimization with weighted principal component analysis is used to achieve an optimal design of maintenance modules as well as repair policy. The methodology presented in this paper provides an efficient way to design a system having nonidentical components and arbitrary repair time distributions with consideration of the variety of maintenance policies as well as the diversity of system operating conditions.
Characterization of alkylphosphonic acid vapors using atmospheric flow tube–ion trap mass spectrometry
Authors: Morrison Kelsey A. , Clowers Brian H.
Published: May 2018

Rationale

A key aspect of detecting hazardous compounds at ultra‐trace levels for processing, compliance, and clean‐up purposes involves developing methods that are not only sensitive, but also highly selective with minimal sampling effort. Atmospheric flow tube mass spectrometry (AFT‐MS) using dielectric barrier discharge ionization has emerged as a technique that combines such features for vapor detection. AFT‐MS is thus appealing for application to ambient screening for chemical warfare agents (CWAs) and their degradation products. Initial characterization of AFT‐MS for CWA detection necessitates examining less harmful simulant species. A predominant hydrolysis product of most organophosphorus CWAs is methylphosphonic acid and most other hydrolysis products consist of some form of an alkylphosphonic acid.

Methods

An application of AFT‐MS is presented wherein a homologous series of four alkylphosphonic acids (methyl‐, ethyl‐, propyl‐, and t‐butylphosphonic acid) were first qualitatively evaluated as anionic clusters with nitrate. These anionic adducts were subsequently quantified from non‐equilibrium headspace vapor sampled over alkylphosphonic acid solutions in methanol.

Results

The series of phosphonic acids demonstrated consistent relative ion abundances thought to be related at least in part to the relative vapor pressures depending on their alkyl chains. For quantitation, the resulting linear ranges were found to be 2 to 50 ppmsoln for methylphosphonic acid, 5 to 50 ppmsoln for ethylphosphonic acid, and 2 to 25 ppmsoln for propylphosphonic acid and t‐butylphosphonic acid; quality controls of 15 ppmsoln were used to assess the quantitation accuracy.

Conclusions

Although measured over a limited dynamic range, the real‐time analysis afforded by this method suggests the feasibility of using thermodynamically stable anionic adducts to monitor organophosphorus compounds via AFT‐MS. In addition, this is proof‐of‐concept for the use of this ambient sensing technique to detect phosphonic acids. Furthermore, a discussion is included regarding gaps in clustering thermodynamics literature that would assist in uncovering physical or chemical explanations for observed trends.
Robust fusion time‐varying Kalman estimators for multisensor networked systems with mixed uncertainties
Authors: Liu Wen‐Qiang , Wang Xue‐Mei , Deng Zi‐Li
Published: May 2018

This paper addresses the problem of designing robust fusion time‐varying Kalman estimators for a class of multisensor networked systems with mixed uncertainties including multiplicative noises, missing measurements, packet dropouts, and uncertain‐variance linearly correlated measurement and process white noises. By the augmented approach, the original system is converted into a stochastic parameter system with uncertain noise variances. Furthermore, applying the fictitious noise approach, the original system is converted into one with constant parameters and uncertain noise variances. According to the minimax robust estimation principle, based on the worst‐case system with the conservative upper bounds of the noise variances, the five robust fusion time‐varying Kalman estimators (predictor, filter, and smoother) are presented by using a unified design approach that the robust filter and smoother are designed based on the robust Kalman predictor, which include three robust weighted state fusion estimators with matrix weights, diagonal matrix weights, and scalar weights, a modified robust covariance intersection fusion estimator, and robust centralized fusion estimator. Their robustness is proved by using a combination method, which consists of Lyapunov equation approach, augmented noise approach, and decomposition approach of nonnegative definite matrix, such that their actual estimation error variances are guaranteed to have the corresponding minimal upper bounds for all admissible uncertainties. The accuracy relations among the robust local and fused time‐varying Kalman estimators are proved. A simulation example is shown with application to the continuous stirred tank reactor system to show the effectiveness and correctness of the proposed results.
Subsidies from anadromous sea lamprey (Petromyzon marinus) carcasses function as a reciprocal nutrient exchange between marine and freshwaters
Authors: Weaver D.M. , Coghlan S.M. , Greig H.S. , Klemmer A.J. , Perkins L.B. , Zydlewski J.
Published: May 2018

Nutrient and energy flows across ecosystem boundaries subsidize recipient communities and influence bottom‐up processes in food webs. Migratory fish such as anadromous sea lamprey provide a pulse of marine‐derived nutrients and energy to Atlantic coastal streams in spring when organisms would otherwise be subject to limiting resources. We conducted sea lamprey carcass addition experiments to characterize the role of subsidies on producer and consumer trophic pathways by manipulating subsidy quantity and light exposure. We demonstrated that producer and decomposer productivity is constrained by nutrients during spring; however, these limitations were reduced in producers as light limitations intensified through riparian shading. We observed no significant effects of increasing carcass subsidies on producer and decomposer biomass. Our results suggest that high densities of carcass subsidies may stimulate primary productivity; however, these effects are mediated by the degree of riparian shading, which demonstrated a onefold to fourfold difference in biomass accrual. In addition, sea lamprey carcass nutrients were captured by larval conspecifics. Stable isotopes analysis demonstrated that adult sea lamprey carcass tissue was relatively enriched in 15N and 13C isotopes compared with larvae. We observed significant enrichment in the 13C isotope among larvae sampled after 2 and 4 weeks of exposure to adult carcass nutrients. Our work suggests that a portion of sea lamprey subsidies serve as a reciprocal exchange between freshwaters and the ocean. We highlight that this cross‐ecosystem linkage is likely influenced by subsidy quantity from donor systems and is mediated by environmental characteristics affecting the recipient system.
A decision support system to diagnose factors limiting stream trout fisheries
Authors: Holmes R. , Matthaei C. , Gabrielsson R. , Closs G. , Hayes J.
Published: May 2018

Maintaining or restoring productive freshwater fisheries is a key challenge for resource managers. However, the inherent uncertainty and complexity of managing fisheries, often based on scant environmental data, make it difficult for managers and the public to reach consensus on appropriate actions. To help deal with this issue, we created a literature‐based decision support system to diagnose limiting factors for stream brown trout fisheries. Once limiting factors are determined, appropriate management actions can be tailored to address them. Our Bayesian belief network (BBN)‐based framework serves 2 functions: (a) It directs users to assemble a parsimonious environmental data set to inform stream fishery management, and (b) it integrates and interrogates these data to generate standardized and testable hypotheses about which environment factors are likely to limit trout productivity. The BBN has been trained on brown trout because among freshwater fish, this species has the richest literature base and is highly valued worldwide. However, the framework could be adapted for other stream fish. We applied our BBN to the Horokiri Stream, a data‐rich catchment in Wellington, New Zealand. The BBN probability outputs were comparable with the conclusions of 5 experienced fishery biologists following their detailed investigation into the factors that led to the loss of the Horokiri brown trout fishery between 1951 and 1990.
Spatial and temporal variance in fatty acid and stable isotope signatures across trophic levels in large river systems
Authors: Fritts A. K. , Knights B. C. , Lafrancois T. D. , Bartsch L. A. , Vallazza J. M. , Bartsch M. R. , Richardson W. B. , Karns B. N. , Bailey S. W. , Kreiling R. M.
Published: May 2018

Fatty acid and stable isotope signatures allow researchers, managers, and policy makers to better understand food webs, food sources, and trophic relationships. Research in marine and lentic systems has indicated that the variance of these biomarkers can exhibit substantial differences across spatial and temporal scales, but this type of analysis has not been completed for large river systems. Our objectives were (a) to evaluate variance structures for fatty acids and stable isotopes (i.e., δ13C and δ15N) of seston, threeridge mussels, hydropsychid caddisflies, gizzard shad, and bluegills across spatial scales (10s–100s of km) in large rivers of the Upper Mississippi River Basin, USA, that were sampled annually for 2 years and (b) to evaluate the implications of this variance on the design and interpretation of trophic studies. The greatest variance for both stable isotopes was present at the largest spatial scale for all taxa (except seston δ15N), indicating that these isotopic signatures are responding to factors at a larger geographic level rather than being influenced by local‐scale alterations. Conversely, the greatest variance for fatty acids was present at the smallest spatial scale (i.e., among individuals) for all taxa except caddisflies, indicating that the physiological and metabolic processes that influence fatty acid profiles can differ substantially between individuals at a given site. Our results highlight the need to consider the spatial partitioning of variance during sample design and analysis, as some taxa may not be suitable for use in assessing ecological questions at larger spatial scales.
Velocity‐aware handover prediction in LEO satellite communication networks
Authors: Hu Xin , Song Hangyu , Liu Shuaijun , Wang Weidong
Published: May 2018

The previous satellite handover prediction and ground cellular network were mainly studied in the static steady satellite links. Rare work has been conducted to resolve the dynamic satellite handover prediction. The complexity of this problem comes from that the multiple link states of the satellite change with the users' movements. To reckon with these challenges, the time‐expanded graph, in which the covering satellite and the handover strategy are treated as its node and arc weight respectively, is constructed in this paper. And the handover prediction is viewed as finding the shortest path of the time‐expanded graph dynamically based on the previous state with the perception of velocity. Compared with the previous approaches in the satellite handover prediction, the proposed method can effectively avoid the handover prediction failure and reduce the redundant computation triggered by static update algorithms. Simulation results are presented to show the improvements.
The pedagogical value of conceptual metaphor for secondary science teachers
Authors: Daane Abigail R. , Haglund Jesper , Robertson Amy D. , Close Hunter G. , Scherr Rachel E.
Published: May 2018

The abstract nature of energy encourages metaphorical language. In educational settings, teachers and students use conceptual metaphors subconsciously to express their ideas about what energy is or how it functions in particular scenarios. However, research on scientific analogies and metaphors has predominantly focused on explicit instructional analogies, rather than implicit, everyday metaphor. In professional development for secondary science teachers, we sought to make explicit the embeddedness and ubiquity of conceptual metaphor in everyday language and in science—particularly, in energy—to expand teachers’ understanding of their students’ ideas. In our microcase study, we observed and video recorded four secondary teachers discussing metaphor. We used interaction analysis methods, focusing on how both discursive and nonverbal interactions between people, objects, and environment change over time, to analyze the collected data. We found evidence of teachers’ (1) learning about conceptual metaphor theory and (2) finding value in understanding conceptual metaphor in educational settings. In particular, teachers acknowledged that if they identify implicit metaphors in students’ science language, they will better understand students’ ideas about energy. We present possible mechanisms for teacher learning about and valuing of energy metaphor; we also suggest how to support teachers in noticing and valuing metaphors for energy instruction.
A bias‐corrected estimator in multiple imputation for missing data
Authors: Tomita Hiroaki , Fujisawa Hironori , Henmi Masayuki
Published: May 2018

Multiple imputation (MI) is one of the most popular methods to deal with missing data, and its use has been rapidly increasing in medical studies. Although MI is rather appealing in practice since it is possible to use ordinary statistical methods for a complete data set once the missing values are fully imputed, the method of imputation is still problematic. If the missing values are imputed from some parametric model, the validity of imputation is not necessarily ensured, and the final estimate for a parameter of interest can be biased unless the parametric model is correctly specified. Nonparametric methods have been also proposed for MI, but it is not so straightforward as to produce imputation values from nonparametrically estimated distributions. In this paper, we propose a new method for MI to obtain a consistent (or asymptotically unbiased) final estimate even if the imputation model is misspecified. The key idea is to use an imputation model from which the imputation values are easily produced and to make a proper correction in the likelihood function after the imputation by using the density ratio between the imputation model and the true conditional density function for the missing variable as a weight. Although the conditional density must be nonparametrically estimated, it is not used for the imputation. The performance of our method is evaluated by both theory and simulation studies. A real data analysis is also conducted to illustrate our method by using the Duke Cardiac Catheterization Coronary Artery Disease Diagnostic Dataset.
Synthesis of Aqueous Dispersible Reduced Graphene Oxide by the Reduction of Graphene Oxide in Presence of Carbonic Acid
Authors: Wadekar Pravin H. , Ahirrao Dinesh J. , Khose Rahul V. , Pethsangave Dattatray A. , Jha Neetu , Some Surajit
Published: May 2018

In this article, we have proposed a simple, environmentally benign and highly effective method for the reduction of graphene oxide (GO) by using carbonic acid as a chemical reducing agent to synthesize the reduced graphene oxide (rGO). Carbonic acid has been synthesized by mixing the dry ice (solid CO2) with deionized water and by the mixing of acetic acid and sodium bicarbonate. The formed carbonic acid utilized to remove the oxygen‐containing functionalities of GO to produce rGO. Surprisingly, the synthesized rGO has shown aqueous dispersible property, which helps to disperse rGO in water for a prolonged time. The electrochemical activity of resulting materials has been achieved by measuring specific capacitance by cyclic voltammetry (CV) and galvanostatic charge‐discharge (GCD). Specific capacitance of resultant material is 350.3 F g−1 at 1 A g−1 with good cyclic stability performance indicating supercapacitive nature of the resultant material. According to the data obtained, it is observed that as‐prepared carbonic acid is capable of producing carboxyl functionalized graphene which leads to disperse rGO in water. This preparative method will overcome the problems to prepare rGO dispersion in aqueous medium rather than in hazardous organic solvents.
Studies of Viscosity Coefficient and Density Properties of Imidazolium Based Ionic Liquids in Aqueous Solutions at Different Temperatures
Authors: Patil Pramod P. , Shaikh Vasim R. , Gupta Gaurav R. , Patil Pankaj D. , Borse Amulrao U. , Patil Kesharsingh J.
Published: May 2018

The densities and viscosity coefficients for binary aqueous solutions of imidazolium based ionic liquids (IL′s), namely 1‐Butyl‐3‐Methylimidazolium Bromide (0.02281 to 0.17232 mol⋅kg‐1) and 1‐Butyl‐3‐Methylimidazolium Chloride (0.01948 to 0.19816 mol⋅kg‐1) have been measured at 293.15, 298.15, and 303.15 K, and at atmospheric pressure, respectively. Using the density data, the apparent molar volumes (
) and partial molar volumes (
) of solutes at finite concentrations and at infinitely dilute solutions (
) were estimated. The limiting partial molar volumes of the constituent ions are also reported. The viscosity A, B and D coefficients of Jones‐Dole equation for the studied IL′s are obtained by using viscosity coefficient data. It is observed that viscosity A and B coefficients are positive in magnitude for studied IL′s while the temperature coefficient of B (dB/dT) is of negative, signifying that cations are water structure making ions. The application of Vand's equation to viscosity data and estimation of volume fractions of the solute enabled us to obtain Einstein‐Simha factor and particle interaction coefficient for the ion‐pairs. The analysis of the results indicates that imidazolium cations act as electrostrictive water structure making ions.
Fabrication of Hollow Co3O4 Nanospheres and Their Nanocomposites of CNT and rGO as High‐Performance Anodes for Lithium‐Ion Batteries
Authors: Kesavan Thangaian , Gunawardhana Nanda , Senthil Chenrayan , Kundu Manab , Maduraiveeran Govindhan , Yoshio Masaki , Sasidharan Manickam
Published: May 2018

We report an efficient method for fabrication of Co3O4 hollow nanospheres (CHN) by self‐assembly process using poly(styrene–b–2‐vinylpyridine–b–ethylene oxide) micelle as a soft template and [(NH4)2Co(SO4)2.6H2O] as cobalt source. To mitigate the capacity fading of Co3O4, nanocomposites of CHN with multi‐walled carbon nanotubes (MWCNT) and reduced graphene oxide (rGO) were synthesized by a simple sonication followed by hydrothermal treatment. The cationic shell block with positively charged 2‐vinylpyridine units (pH 4) electrostatically interacts with anionic Co(II) species during the self‐assembly and subsequently condenses to form CHN. A combined structural and morphological characterization indicates that the CHN, rGO, and MWCNT were well integrated within the nanocomposite. Powder X‐ray diffraction (XRD) pattern of pristine CHN clearly confirms the formation of pure cubic phase of Co3O4. The morphological features such as particle size, void space diameter, and shell thickness were evaluated using a transmission electron microscope (TEM) and average diameter of hollow nanosphere was found to be 27 ± 2 nm. The nanocomposite CHN/rGO and CHN/CNT constructed electrodes exhibit higher charge/discharge capacities (∼943 mAh g−1) when compared to pristine CHN based electrode (∼678 mAh g−1) in LIBs after 50 cycles. Both CHN/rGO and CHN/CNT deliver high specific capacity, rate capability, and electrode stability vis‐à‐vis cycling performance compared to CHN.
Elemental Sulfur Participates in the Decarboxylative Coupling of Oxidized 2‐Aminophenol and Phenylglyoxylic Acid
Authors: Yuan Xinglong , Liu Yafeng , Qin Mingda , Yang Xueying , Chen Baohua
Published: May 2018

A simple and practical elemental sulfur‐catalyzed one‐pot method for the synthesis of benzoxazole derivatives has been developed. The protocol uses inexpensive elemental sulfur as the catalyst and highly effective to promote this transformation without the aid of any metal salts. The corresponding benzoxazoles were achieved in good to high yields. Compared with previous methods, becouse of elemental sulfur promoted decarboxylative cyclization was unique and allow highly flexible and wide range of applications displays great potential for replacing existing methodologies.
Anticorrosive, Ultralight, and Flexible Carbon‐Wrapped Metallic Nanowire Hybrid Sponges for Highly Efficient Electromagnetic Interference Shielding
Authors: Wan Yan‐Jun , Zhu Peng‐Li , Yu Shu‐Hui , Sun Rong , Wong Ching‐Ping , Liao Wei‐Hsin
Published: May 2018

Metal‐based materials with exceptional intrinsic conductivity own excellent electromagnetic interference (EMI) shielding performance. However, high density, corrosion susceptibility, and poor flexibility of the metal severely restrict their further applications in the areas of aircraft/aerospace, portable and wearable smart electronics. Herein, a lightweight, flexible, and anticorrosive silver nanowire wrapped carbon hybrid sponge (Ag@C) is fabricated and employed as ultrahigh efficiency EMI shielding material. The interconnected Ag@C hybrid sponges provide an effective way for electron transport, leading to a remarkable conductivity of 363.1 S m−1 and superb EMI shielding effectiveness of around 70.1 dB in the frequency range of 8.2–18 GHz, while the density is as low as 0.00382 g cm−3, which are among the best performances for electrically conductive sponges/aerogels/foams by far. More importantly, the Ag@C sponge surprisingly exhibits super‐hydrophobicity and strong corrosion resistance. In addition, the hybrid sponges possess excellent mechanical resilience even with a large strain (90% reversible compressibility) and an outstanding cycling stability, which is far better than the bare metallic aerogels, such as silver nanowire aerogels and copper nanowire foams. This strategy provides a facile methodology to fabricate lightweight, flexible, and anticorrosive metal‐based sponge for highly efficient EMI shielding applications.
Selective CXCR4+ Cancer Cell Targeting and Potent Antineoplastic Effect by a Nanostructured Version of Recombinant Ricin
Authors: Díaz Raquel , Pallarès Victor , Cano‐Garrido Olivia , Serna Naroa , Sánchez‐García Laura , Falgàs Aïda , Pesarrodona Mireia , Unzueta Ugutz , Sánchez‐Chardi Alejandro , Sánchez Julieta M. , Casanova Isolda , Vázquez Esther , Mangues Ramón , Villaverde Antonio
Published: May 2018

Under the unmet need of efficient tumor‐targeting drugs for oncology, a recombinant version of the plant toxin ricin (the modular protein T22‐mRTA‐H6) is engineered to self‐assemble as protein‐only, CXCR4‐targeted nanoparticles. The soluble version of the construct self‐organizes as regular 11 nm planar entities that are highly cytotoxic in cultured CXCR4+ cancer cells upon short time exposure, with a determined IC50 in the nanomolar order of magnitude. The chemical inhibition of CXCR4 binding sites in exposed cells results in a dramatic reduction of the cytotoxic potency, proving the receptor‐dependent mechanism of cytotoxicity. The insoluble version of T22‐mRTA‐H6 is, contrarily, moderately active, indicating that free, nanostructured protein is the optimal drug form. In animal models of acute myeloid leukemia, T22‐mRTA‐H6 nanoparticles show an impressive and highly selective therapeutic effect, dramatically reducing the leukemia cells affectation of clinically relevant organs. Functionalized T22‐mRTA‐H6 nanoparticles are then promising prototypes of chemically homogeneous, highly potent antitumor nanostructured toxins for precise oncotherapies based on self‐mediated intracellular drug delivery.
Liquid‐Phase Exfoliated Indium–Selenide Flakes and Their Application in Hydrogen Evolution Reaction
Authors: Petroni Elisa , Lago Emanuele , Bellani Sebastiano , Boukhvalov Danil W. , Politano Antonio , Gürbulak Bekir , Duman Songül , Prato Mirko , Gentiluomo Silvia , Oropesa‐Nuñez Reinier , Panda Jaya‐Kumar , Toth Peter S. , Del Rio Castillo Antonio Esau , Pellegrini Vittorio , Bonaccorso Francesco
Published: May 2018

Single‐ and few‐layered InSe flakes are produced by the liquid‐phase exfoliation of β‐InSe single crystals in 2‐propanol, obtaining stable dispersions with a concentration as high as 0.11 g L−1. Ultracentrifugation is used to tune the morphology, i.e., the lateral size and thickness of the as‐produced InSe flakes. It is demonstrated that the obtained InSe flakes have maximum lateral sizes ranging from 30 nm to a few micrometers, and thicknesses ranging from 1 to 20 nm, with a maximum population centered at ≈5 nm, corresponding to 4 Se–In–In–Se quaternary layers. It is also shown that no formation of further InSe‐based compounds (such as In2Se3) or oxides occurs during the exfoliation process. The potential of these exfoliated‐InSe few‐layer flakes as a catalyst for the hydrogen evolution reaction (HER) is tested in hybrid single‐walled carbon nanotubes/InSe heterostructures. The dependence of the InSe flakes' morphologies, i.e., surface area and thickness, on the HER performances is highlighted, achieving the best efficiencies with small flakes offering predominant edge effects. The theoretical model unveils the origin of the catalytic efficiency of InSe flakes, and correlates the catalytic activity to the Se vacancies at the edge of the flakes.
Multiscale Hierarchical Design of a Flexible Piezoresistive Pressure Sensor with High Sensitivity and Wide Linearity Range
Authors: Shi Jidong , Wang Liu , Dai Zhaohe , Zhao Lingyu , Du Mingde , Li Hongbian , Fang Ying
Published: May 2018

Flexible piezoresistive pressure sensors have been attracting wide attention for applications in health monitoring and human‐machine interfaces because of their simple device structure and easy‐readout signals. For practical applications, flexible pressure sensors with both high sensitivity and wide linearity range are highly desirable. Herein, a simple and low‐cost method for the fabrication of a flexible piezoresistive pressure sensor with a hierarchical structure over large areas is presented. The piezoresistive pressure sensor consists of arrays of microscale papillae with nanoscale roughness produced by replicating the lotus leaf's surface and spray‐coating of graphene ink. Finite element analysis (FEA) shows that the hierarchical structure governs the deformation behavior and pressure distribution at the contact interface, leading to a quick and steady increase in contact area with loads. As a result, the piezoresistive pressure sensor demonstrates a high sensitivity of 1.2 kPa−1 and a wide linearity range from 0 to 25 kPa. The flexible pressure sensor is applied for sensitive monitoring of small vibrations, including wrist pulse and acoustic waves. Moreover, a piezoresistive pressure sensor array is fabricated for mapping the spatial distribution of pressure. These results highlight the potential applications of the flexible piezoresistive pressure sensor for health monitoring and electronic skin.
Transformation of Amorphous Polyphosphate Nanoparticles into Coacervate Complexes: An Approach for the Encapsulation of Mesenchymal Stem Cells
Authors: Müller Werner E. G. , Wang Shunfeng , Tolba Emad , Neufurth Meik , Ackermann Maximilian , Muñoz‐Espí Rafael , Lieberwirth Ingo , Glasser Gunnar , Schröder Heinz C. , Wang Xiaohong
Published: May 2018

Inorganic polyphosphate [polyP] has proven to be a promising physiological biopolymer for potential use in regenerative medicine because of its morphogenetic activity and function as an extracellular energy‐donating system. Amorphous Ca2+–polyP nanoparticles [Ca–polyP‐NPs] are characterized by a high zeta potential with −34 mV (at pH 7.4). This should contribute to the stability of suspensions of the spherical nanoparticles (radius 94 nm), but make them less biocompatible. The zeta potential decreases to near zero after exposure of the Ca–polyP‐NPs to protein/peptide‐containing serum or medium plus serum. Electron microscopy analysis reveals that the particles rapidly change into a coacervate phase. Those mats are amorphous, but less stable than the likewise amorphous Ca–polyP‐NPs and are morphogenetically active. Mesenchymal stem cells grown onto the polyP coacervate show enhanced growth/proliferation and become embedded in the coacervate. These results suggest that the Ca–polyP coacervate, formed from Ca–polyP‐NPs in the presence of protein, can act as an adaptable framework that mimics a niche and provides metabolic energy in bone/cartilage engineering.
Determination of Maximum Surface Heat Flux during Jet Impingement Surface Quenching with a Sharp Edge Nozzle
Authors: Agrawal Chitranjan , Kumar Ravi , Gupta Akhilesh , Chatterjee Barun
Published: May 2018

The maximum surface heat flux is determined during jet impingement quenching of hot vertical stainless steel surface of 800 ± 10 °C initial temperature. Water jet through a sharp edge nozzle of 24 ± 1 °C temperature is injected on a vertical test surface of 0.25 mm thickness. The investigation is made up for stagnation point to 24 mm downstream location above and below of the stagnation point. Water flow is regulated to maintain the jet Reynolds number in the range of 5000–24,000. It has been observed that maximum surface heat flux is highest for the stagnation point and reduces monotonically for the downstream spatial locations. The decrease in maximum surface heat flux is higher for the locations above the stagnation point as compared to the locations below the stagnation point. However, for the entire measured spatial locations the maximum surface heat flux increases with the rise in jet diameter and coolant flow rate. The proposed correlation for the maximum surface heat flux predicts experimental data within an error band of ±15%.
Concise Review: Prostate Cancer Stem Cells: Current Understanding
Authors: Skvortsov Sergej , Skvortsova Ira-Ida , Tang Dean G. , Dubrovska Anna
Published: May 2018

Prostate cancer (PCa) is heterogeneous, harboring phenotypically diverse cancer cell types. PCa cell heterogeneity is caused by genomic instability that leads to the clonal competition and evolution of the cancer genome and by epigenetic mechanisms that result in subclonal cellular differentiation. The process of tumor cell differentiation is initiated from a population of prostate cancer stem cells (PCSCs) that possess many phenotypic and functional properties of normal stem cells. Since the initial reports on PCSCs in 2005, there has been much effort to elucidate their biological properties, including unique metabolic characteristics. In this Review, we discuss the current methods for PCSC enrichment and analysis, the hallmarks of PCSC metabolism, and the role of PCSCs in tumor progression.