bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of a Heat Sink for an Electronic Component in ABB Drive using Different Types of Fins
Authors: Khurshid Hassan , Silaipillayarputhur Karthik , Mughanam Tawfiq Al
Published: December 2018

This paper considers an analytical approach in the design of a passive heat sink for an ABB electrical drive. The heat sink is intended to dissipate a certain amount of heat energy and to maintain the surface temperature of an electronic communication board at the prescribed temperature. The maximum size of the heat sink is known due to the existing space constraint. This paper details the step by step procedure in the development of a passive heat sink that functions based on the natural convection. Two commonly used fins such as rectangular plate fins and rectangular pins fins were considered for the project. A parametric study was considered wherein a relationship was developed between the convection heat transfer coefficient and the air flow. Likewise, the impact of convection heat transfer coefficient was seen on the rate of heat transfer and the fin geometry.
An analytical framework for smart manufacturing
Authors: Kulkarni Amogh , Balasubramanian Daniel , Karsai Gabor , Denno Peter
Published: December 2018

Smart manufacturing is an emerging paradigm for the next generation of manufacturing systems. One key to the success of smart manufacturing is the ability to use the production data for defining predictive and descriptive models and their analyses. However, the development and refinement of such models is a labor- and knowledgeintensive activity that involves acquiring data, selecting and refining an analytical method and validating results. This paper presents an analytical framework that facilitates these activities by allowing ad-hoc analyses to be rapidly specified and performed. The proposed framework uses a domain-specific language to allow manufacturing experts to specify analysis models in familiar terms and includes code generators that automatically generate the lower-level artifacts needed for performing the analysis. We also describe the use of our framework with an example problem.
A hybrid optimization approach for setup planning with tolerance constraints
Authors: Wu Wenbo , Zeng Jiani , Huang Zhengdong
Published: December 2018

Computer-aided process planning (CAPP) plays an important role in integrated manufacturing system and it can serve as a bridge between CAD and CAM. As a crucial part of CAPP, setup planning is a multi-constraint problem, in which the precision takes priority over efficiency. However, instead of precision constraints, traditional optimization methods have paid much more attention to efficiency requirements. This leads to the reduction in the precision of the final parts. This paper develops an optimization approach for solving computer-aided setup planning problem, which takes into account various constraints, especially the precision requirements specified by designers. First, objective function of the optimization model is formulated and a series of constraints, including feature precedence, tool approaching direction (TAD), and precision requirements are systematically created. Next, the model is solved by using a hybrid particle swarm optimization algorithm. In order to overcome the local optimum trap, mutation and exchange operations are adopted from the genetic algorithm. Finally, a part is tested in the case study and the validation of this method is proved.
Intérêt des dossiers de santé électroniques hospitaliers pour la recherche clinique
Authors: Dupont Danielle , Beresniak Ariel , Kalra Dipak , Coorevits Pascal , De Moor Georges
Published: December 2018

Les dossiers de santé électroniques hospitaliers contribuent à l’amélioration de la qualité des soins en permettant une meilleure gestion des informations cliniques. Les bases de données numériques ainsi constituées facilitent l’échange des informations de santé avec les prestataires de soins et optimisent la coordination multidisciplinaire pour de meilleurs résultats thérapeutiques. Le projet européen EHR4CR (electronic health records for clinical research) a développé une plateforme pilote innovante permettant de réutiliser ces données numériques pour la recherche clinique. En améliorant et en accélérant les procédures de recherche clinique, cette approche permet d’envisager la réalisation d’études cliniques de manière plus efficiente, plus rapide et plus économique.
Radiation exposure of very-low-birth-weight infants in neonatal intensive care units in Korea
Authors: Park M.J. , Kim S.S. , Park G.Y. , Hong H.S.
Published: December 2018

To our knowledge, no study has reported the radiation doses of neonates admitted to neonatal intensive care units (NICUs) in Korea. Therefore, we evaluated the radiation frequency and dose of radiation performed in NICUs using mobile X-ray machines. We retrospectively analyzed the number of radiographs and doses among 290 very low-birth-weight infants (VLBWIs) admitted at our hospital between 2011 and 2016. We compared X-ray frequencies and radiation doses according to clinical characteristics and morbidities. The entrance surface doses (ESDs) were calculated using the non-dosimeter dosimetry formula. The median number of radiographs per infant was 26, and about 25% neonates had over 50 radiographs. The number of radiographs taken was higher for infants with low-birth-weight (LBW), respiratory distress syndrome, bronchopulmonary dysplasia, and longer central venous catheterization duration (p < 0.001 for all). The cumulative ESD was 0.18 to 9.89 mGy, and the ESD per radiograph was 0.049 to 0.069 mGy. The LBW and the more severe the neonates’ condition, the greater was the radiation exposure. It is difficult to reduce the number of radiographic examinations, but the quality of examinations must be improved without compromising patient care. Additional studies are needed to minimize the cumulative exposure dose and achieve optimal image quality.
International Service Learning Program in Tourism Village Development Case Studies: Kampung Kabondok and Kampung Pasunga, Central Sumba, Indonesia
Authors: Octarino Christian Nindyaputra , Wololi Reynaldo Yosua , Wicaksono Arbiter Adi
Published: December 2018

Tourism is one of the leading sectors of Central Sumba District. In addition to natural environment, Central Sumba has rich of traditional culture that maintained in their social life. Kampung Pasunga, located in Anakalang village, is one of traditional village that have been designated as a Tourism Village by the local government. Kampung Kabondok, located in Makatakeri Village, not yet established as a tourist village but it has a great tourism potential because of their cultural traditions. This Service Learning Program focuses on mentoring and empowering the community in order to develop the tourism village. The participants for about 4 wk stay with the local community to be able to understand the problems faced and then provide recommendations that need to be done. Infrastructure, quality of human resources, and tourism promotion are key problems in the development of a tourism village. Approach method and socializing with residents become a very important point, to ensure the proposed programs are the real need of the community. The final outcome are proposed programs or recommendations that divided into short, medium and long term, that will be presented to local community and stakeholders, as consideration for the local development plan.
The Use of Cambridge Scriptural Reasoning (CSR) Texts for Inter-Faith Dialogue in Classroom: Some Pedagogical Proposals
Authors: Saragih Denni , Mokorowu Yanny , Peranginangin Prasasti
Published: December 2018

Recent developments in Indonesian society show an alarming growth of religious intolerance. The paper proposes that one of ways that can contribute to remedy the situation is an Inter-faith dialogue in classroom using Cambridge Scriptural Reasoning (CSR) texts. The texts provide a primary source for understanding fundamental beliefs and focus on less controversial issues. Acknowledging the sensitivity of handling religious texts, the paper reports an exploration of the possibility and challenges of doing interfaith dialogues in a classroom using CSR texts. Based on several class experiments and qualitative interviews of the participants, the approach results in positive experience of the participants. The paper, thus, recommends three pedagogical principles. The use of the texts must have the consent of all students; the conclusion of textual meaning gives a prominent authority to the insights of its adherent; and at the end of each session, students from other religions provide testimonial on changed perception through the dialogue. As such, the paper recommends the use of CSR texts in a course on religion, particularly in Christian universities in Indonesia, as a contribution to mutual understanding and religious harmony.
Service Learning on Inclusive Design: Adaptive Home for Wheelchair-Using Persons with Disabilities
Authors: Tanuwidjaja Gunawan , Lisandra Felicia , Magdalena Agnes , Negara Josephin Martina , Hayati Arina
Published: December 2018

More than 1 000 000 000 people in the world live with disabilities, and 200 000 000 among them experience heavy functioning difficulties. Persons with Disabilities (PwDs) usually have limited economic participation, faced poverty and limited access to housing. Service Learning Program in Architecture Department (Inclusive Design Course) was created to answer the Persons with Disabilities (PwDs) needs. The course was supported by UBCHEA (https://unitedboard.org/) for the program of Service Learning of Inclusive Design for Homes and Schools in Surabaya and Bandung: Participatory Design and Campaign. It started with accessibility evaluation at PwDs’ residences (wheelchair users) in Surabaya. Simulation as PwDs in Petra Campus was also conducted to create empathy to wheelchair users. Later on, an inclusive-and-universal design was proposed. Three participatory workshops in Surabaya and Bandung were conducted to review it. The new design was produced to cater the wheelchair users. In conclusion, role play and participatory design process was the important key points of the program’s success.
Service Learning on Inclusive Design: Sidewalk Redesign for Siwalankerto, Surabaya, Indonesia
Authors: Tanuwidjaja Gunawan , Levina Claudia , Tandiono Cynthia , Tandiono Christian
Published: December 2018

Public facilities and transportation infrastructure were very important for all residents including Persons with Disabilities (PwDs). Sidewalk should be safe and easy to use for all kind of users, ranging from the elderly, children, and the PwDs including wheelchair users, visual impairment, low vision disability, etc. The sidewalk should be safe, which means it should be inclusive yet also meets the standards. The Service Learning and research program in Petra Christian University’s Architecture Program was conducted with literature study, observation, discussion and interviews with users at Siwalankerto street’s sidewalks. The design would be implemented in Petra's area in the following year.
Utilizing Social Norms Marketing to Address E-Cigarette Use on College Campuses
Authors: Scholly Kristen , Garcia Lynn , Dodge Stormy , Pokhrel Pallav
Published: December 2018

E-cigarette use is a serious health concern among adolescents and young adults. This study identifies factors associated with e-cigarette use in an effort to better understand what impacts college students’ decisions to use this tobacco product. This study utilizes data from a survey conducted at a research institution and two community colleges located in Hawaii. A multivariate logistic regression analysis identified key risk factors associated with college student e-cigarette use. Independent factors associated with e-cigarette use included use of traditional cigarettes and having one or more family members or friends who currently used e-cigarettes. Exposure to online e-cigarette information was also associated with increased odds of e-cigarette use. The study findings have important implications for e-cigarette control among adolescents and young adults. Service learning students can take an active role in developing social norms marketing campaigns designed to communicate the risks of e-cigarette use and counter marketing ploys that foster unsubstantiated beliefs regarding the benefits of e-cigarette use.
The Implementation of Service-learning in Typography Class to Design the Cover of Street Vendor Stalls in Surabaya, Indonesia.
Authors: Damajanti Maria Nala , Yuwono Elisabeth Christine
Published: December 2018

Through Service Learning (S-L) program students of Typography 2 class, Visual Communication Design, Petra Christian University, had an opportunity to learn and applied their knowledge. The selected media is street vendor stall’s cover (it is known as keber Pedagang Kaki Lima or PKL in Indonesia) at Surabaya. This media usually installed in front of the street vendors stall. The cover material is fabric or outdoor vinyl. S-L itself is a new method which applied to Typography 2 class. S-L method was selected as one of learning method which allows students to implementing typography theories to society. According to S-L application a number of experts requiring benefits of parties involved. In this case it is important to measure the success of S-L considers the balancing benefits of students and PKL communities as the target. Therefore, students not only learning from their interaction with community by doing the cover design process but simultaneously must provide significant benefits of PKL. Through depth interviews researcher found benefits of both parties. Students got real experiences as graphic designers by serving the PKL communities as clients. In the other hand the PKL communities received new covers design as a promotional media for their stall.
University Students Teaching Environmental Science to Primary School Students as Service-Learning: Lessons Learned
Authors: McGinley Mark
Published: December 2018

The service-learning pedagogy attempts to enhance student learning by integrating academic study with meaningful community service. This paper discusses lessons learned when attempting to integrate direct service (having S-L students provide science lessons for primary students) and indirect service (having S-L students prepare curriculum guides for use by primary teachers) to maximize academic learning in a course entitled “Ecology: The Science of the Environment” at Lingnan University in Hong Kong. Although the course covered fewer topics when taught using the service-learning pedagogy, S-L students reported that participating in the service-learning project (i) increased their academic learning, (ii) enhanced their interest in science, and (iii) improved their communication and problem solving skills. Based on student feedback received, attempts were made to improve the service-learning experience by (i) altering the course outline so that S-L students have learned the material in class before sharing with the primary students, (ii) providing more input to the focus of their topics, (iii) allowing S-L students to interact with the primary students during their on-site orientation, and (iv) encouraging the primary school teachers to provide immediate feedback to the S-L students at the end of each lesson.
The Long Term Impact of A Rainforest Experience on Chinese Students’ Pro-Environmental Identity and Behavior in Macau
Authors: Tam Nga Ian
Published: December 2018

The phenomenological case study covers the limited research on Chinese students‟ experiences of nature in a tropical rainforest in Thailand. Macau is a very small place with only 20 % of natural resources remaining but Chinese students are born to be detached from these natural environments. Their comfortable lifestyle leads to a rise of unsustainable behavior such as an increased in consumption and household waste. With numerous researches that review the benefits of nature including an enhancement in environmental friendly behavior, a 7 d self-funded experiential learning program in a tropical rainforest in Thailand in 2015 was initiated in fostering 12 Chinese students‟ pro-environmental identity and behavior. Findings show the majority of students‟ pro-environmental identity and behavior is enhanced and they are trying to reconnect with the natural environment more often than before.
Service Learning on Cultural Inclusive Design for Urban Migrants' Villages: Producing Transportable Toilet
Authors: Wicandra Obed Bima , Tanuwidjaja Gunawan , Hoesny Michaela Bella , Soetrisno Monalisa , Erandaru  , Octavia Linda , Subroto Gatot
Published: December 2018

Adaptive-inclusive toilet design strategy was needed to respond the local unique toileting culture of Surabaya people, especially the urban migrants. The urban migrants in Surabaya live insecurely/unsafely in the slums because of the potential of Kampung’s eviction/demolition. Because of their limited economic condition and anxieties about sustainable land occupation, they constructed temporary shelters from the recycled materials. To answer the needs of the migrants’ sanitation, an inclusive portable toilet was produced based on the design principles and their toileting culture. The project involved several steps such as literature review, interview and photo documentation, socialization of healthy toileting culture, participative design workshop, and design development. The program was related to UNDK and supported by UBCHEA grant
Endoscopic treatment of esophageal fistulas after esophagectomy with injection of an alpha-cyanoacrylate monomer: a phase II study
Authors: Ojima Toshiyasu , Nakamura Masaki , Nakamori Mikihito , Katsuda Masahiro , Hayata Keiji , Tsuji Toshiaki , Maruoka Shimpei , Yamaue Hiroki
Published: December 2018

Background and study aims Interventional endoscopic treatments including the application of glue are becoming more frequently used for the treatment of esophageal fistulas. However, there are no prospective studies of endoscopic treatment for esophageal fistulas. This prospective study aims to investigate the efficacy and safety of endoscopic injection of alpha-cyanoacrylate monomer for intractable esophageal fistulas.

Patients and methods This single-center prospective phase II trial included patients with more than 1 wk of conservative medical treatment for intractable esophageal fistulas after esophagectomy. In the image-guided therapy suite, a mixture of alpha-cyanoacrylate monomer and oily contrast agent in a ratio of 0.3 to 1.7 mL was endoscopically injected through the fistula.

Results Twenty-five patients who underwent esophagectomy at Wakayama Medical University Hospital were enrolled in this study. The primary disease was esophageal cancer in 16 patients (64 %) and gastric cancer in the remaining 9 patients (36 %). Complete closure of the esophageal fistula was performed in 22 patients after endoscopic injection of alpha-cyanoacrylate monomer. The overall success rate was 88 %. There was no fistula recurrence in any successful closure cases. Three patients with failed esophageal fistula closure had esophageal cancer with cervical esophageal fistulas and required reoperation of the fistulectomy under general anesthesia. No complications associated with this endoscopic treatment were detected.

Conclusions Endoscopic treatment with injection of alpha-cyanoacrylate monomer facilitated healing of post-esophagectomy fistula in 88 % of patients without complications. This suggests that the treatment is effective and safe for patients with esophageal fistulas.
Stability in the energy space of the sum of N peakons for a modified Camassa-Holm equation with higher-order nonlinearity
Authors: Liu Xingxing
Published: December 2018

Considered herein is the orbital stability in the energy space H1(R) of a decoupled sum of N peakons for a modified Camassa-Holm equation with higher-order nonlinearity. The equation studied here admits single peakon and multi-peakons. Based on our obtained result of the stability of a single peakon and then combining modulation argument with monotonicity of the local energy H1-norm, we get the stability of the sum of N peakons.
Strain engineering the structures and electronic properties of Janus monolayer transition-metal dichalcogenides
Authors: Liu Huating , Huang Zongyu , He Chaoyu , Wu Yanbing , Xue Lin , Tang Chao , Qi Xiang , Zhong Jianxin
Published: December 2018

We studied the structures and electronic properties of Janus transition-metal dichalcogenide monolayers MXY (M = Mo, W; X ≠ Y = S, Se, Te) by first-principles calculations. The results of the electronic band structures and the density of states reveal that all of the MXY monolayers show semiconducting characteristics. Particular attention has been focused on the bandgap engineering by applying in-plane biaxial compressive and tensile strain. It is observed that the bandgap values of the MXY monolayers decrease with the increase of strain degree under the tension and compression biaxial strain, and a semiconductor-to-metal transition can be undergone at a critical value of strain. The possibility of the tunable energy gap over a wide range makes MXY monolayers potential candidates for nanoelectronics and optoelectronics.
Effect of synthesis route on structure and dielectric properties of (1-x)BiFeO3-xBaTiO3 solid solutions and its phase diagram
Authors: Singh Anar , Kumar Arun , Pandey Dhananjai
Published: December 2018

We present here a comparative study of structure, surface morphology, composition analysis, and dielectric properties of (1-x)BiFeO3-xBaTiO3 (BF-xBT) solid solutions, synthesized by two different solid state reaction routes reported in the literature. The results of structural and dielectric studies suggest that BF-xBT ceramics synthesized using BaTiO3, Bi2O3, and Fe2O3 (method-I) as initial ingredients are not monophasic for 0.50 < x < 0.80. In this composition range, we observe the phase coexistence of tetragonal and rhombohedral/pseudocubic phases. The ferroelectric Curie temperature (TC ∼ 400 K) of this tetragonal phase corresponds to the TC of BaTiO3. Composition analysis of these ceramics also confirms the presence of BaTiO3-rich phase. These observations suggest that BaTiO3 does not react completely with Bi2O3 and Fe2O3 when synthesized by method-I. In marked contrast, the BF-xBT solid solutions synthesized by method-II using Bi2O3, Fe2O3, BaCO3, and TiO2 as initial ingredients are compositionally homogeneous and single phase in the entire composition range (0 < x ≤ 1). The average atomic percentage of Bi, Fe, Ba, and Ti for BF-xBT ceramics synthesized by method-II, as obtained from energy dispersive x-ray spectroscopy, is close to the nominal composition within ±2%. Structural and dielectric studies do not reveal any signature of the coexistence of phases in these samples. Using the results of structural and dielectric studies, we also present a new and updated phase diagram of BF-xBT synthesized by method-II.
A 3-mirror surface force balance for the investigation of fluids confined to nanoscale films between two ultra-smooth polarizable electrodes
Authors: van Engers C. D. , Balabajew M. , Southam A. , Perkin S.
Published: December 2018

We present a new technique, based on the Surface Force Balance (SFB), for the direct measurement of surface forces between two ultra-smooth and polarizable gold electrode surfaces across thin fluid films. Combining the direct interferometric measurement of surface separation and contact geometry with smooth electrode surfaces has proved challenging in the past, and for this reason, previous measurements with the SFB typically involved two insulating mica surfaces, or one mica surface and one electrode surface, or an alternative less direct measure of the surface separation. Here, we demonstrate that a 3-mirror interferometer can overcome these difficulties: the setup involves two ultra-smooth electrode/mirror surfaces between which the fluid is confined and a third mirror to allow for interferometric detection of the liquid thickness with nanometer resolution and at thicknesses much smaller than the diffraction limit of the light. We conclude with a proof-of-concept measurement across dry nitrogen gas. The technique should prove useful for studying the properties of fluids confined at the nanoscale inside a slit-pore of controlled electrical potential or subject to applied electric fields.
Single field-of-view tomographic imaging of 3D impurity emission distribution in magnetized edge plasma of LHD
Authors: Kobayashi Taisuke , Kobayashi Masahiro , Iwama Naofumi , Kuzmin Arseniy , Goto Motoshi , Kawamura Gakushi
Published: December 2018

A new tomographic scheme is proposed for reconstructing three dimensional (3D) impurity emission distributions from two dimensional (2D) measurements with a single field-of-view in the magnetized edge plasma in a Large Helical Device (LHD). The 2D image is obtained with a multi-channel fiber array spectrometer, which views the entire region of the edge stochastic magnetic layer of LHD, including divertor plates, divertor legs, the stochastic layer, and the last closed flux surface. The scheme introduces new regularization terms in the Lagrangian function, based on the transport feature in magnetized plasma that the transport parallel to the magnetic field lines is much faster than the transport across the magnetic field, thus assuming smooth distribution in the parallel direction. The scheme is benchmarked with the test data of 3D distribution in the measurement volume, where the effectiveness of the various regularization terms is surveyed and feasibility of the scheme is confirmed. The new scheme is applied to the experimental data in LHD for carbon impurity emissions of C1+ and C3+, where the obtained distributions are discussed taking into account the plasma wall interaction and charge dependence of ionization potentials.
An X-band pulsed electron paramagnetic resonance spectrometer with time resolution improved by a field-programmable-gate-array based pulse generator
Authors: Shi Zhifu , Mu Shiwei , Qin Xi , Dai Yingqiu , Rong Xing , Du Jiangfeng
Published: December 2018

We report an X-band pulsed electron paramagnetic resonance (EPR) spectrometer using a Field-Programmable-Gate-Array (FPGA) based pulse generator. The microwave (MW) pulse length and pulse-pulse interval can be adjusted with 50 ps time resolution. A FPGA based pulse generator is utilized to achieve such time resolution. There are eight pulse channels integrated in the pulse generator. Each channel outputs rectangular pulses with 50 ps time resolution. The spectrometer includes a pulse forming unit, where four high-speed PIN diode switches are controlled by the pulse generator to generate MW pulses. A commercial digital storage oscilloscope is used to record the EPR signal. A customized software is developed to control the components of the spectrometer and to perform data processing task. The usefulness of high time resolution is demonstrated by the results of Rabi oscillation.
Strain measurement of ultrathin epitaxial films using electron diffraction techniques
Authors: Wang G.-C. , Lu T.-M.
Published: December 2018

Many diffraction and imaging techniques have been developed and used to measure the strains in epitaxial films with different degrees of accuracy. In this tutorial, we will focus on measurements of strains in epitaxial films using electron diffraction techniques. These include reflection high-energy electron diffraction (RHEED), azimuthal reflection high-energy electron diffraction, low-energy electron diffraction (LEED), and high-resolution low-energy electron diffraction techniques. These diffraction techniques are surface sensitive and are suitable for in situ measurements of strains in ultrathin epitaxial films quantitatively. In particular, RHEED and LEED are simple to operate and readily available in many laboratories. We discuss the instrument limit of strain measurement in each technique. A nominal definition of the resolving power of an instrument to resolve a strain state is given as the percentage of intrinsic instrumental broadening in the reciprocal unit with respect to the first reciprocal Brillouin zone (2π/lattice constant) of a sample. It is shown that the resolving power of these diffraction techniques ranges from 2% to 0.2%. Experimental strategies without modifying the instrument and to achieve a strain detection capability beyond the definition of the nominal resolving power of these techniques are presented.
Electronic and optical properties of pristine, N- and S-doped water-covered TiO2 nanotube surfaces
Authors: Kenmoe S. , Lisovski O. , Piskunov S. , Zhukovskii Y. F. , Spohr E.
Published: December 2018

For rational design and improvement of electronic and optical properties of water-splitting photocatalysts, the ability to control the band edge positions relative to the water redox potentials and the photoresponse as a function of environmental conditions is essential. We combine ab initio molecular dynamics simulations with ab initio many-body theoretical calculations to predict the bandgap and band edge energies, as well as the absorption spectrum of pristine and N- and S-doped TiO2 nanotubes using the DFT+U and G0W0 approaches. Both levels of theory show similar trends, and N+S-codoping appears to be the optimal system for photocatalytic water splitting both in dry and humid conditions. However, the effect is rather moderate. Compared to DFT+U, the enhanced many-body effects in the G0W0 calculations push the absolute energies of the band edges to higher values and yield increased quasi-particle bandgaps in better agreement with experiment. In dry and humid conditions, the electronic bandgap for all systems is found to be in the range of 6.0–6.2 eV with a redshift from electronic gap to optical gap. The absorption spectra show an optical anisotropy and different absorption thresholds for different light polarizations.
Communication: Water activation and splitting by single metal-atom anions
Authors: Liu Gaoxiang , Miliordos Evangelos , Ciborowski Sandra M. , Tschurl Martin , Boesl Ulrich , Heiz Ulrich , Zhang Xinxing , Xantheas Sotiris S. , Bowen Kit
Published: December 2018

We report experimental and computational results pertaining to the activation and splitting of single water molecules by single atomic platinum anions. The anion photoelectron spectra of [Pt(H2O)]−, formed under different conditions, exhibit spectral features that are due to the anion-molecule complex, Pt−(H2O), and to the reaction intermediates, HPtOH− and H2PtO−, in which one and two O–H bonds have been broken, respectively. Additionally, the observations of PtO− and H2+ in mass spectra strongly imply that water splitting via the reaction Pt− + H2O → PtO− + H2 has occurred. Extending these studies to nickel and palladium shows that they too are able to activate single water molecules, as evidenced by the formation of the reaction intermediates, HNiOH− and HPdOH−. Computations at the coupled cluster singles and doubles with perturbatively connected triples level of theory provide structures and vertical detachment energies (VDEs) for both HMOH− and H2MO− intermediates. The calculated and measured VDE values are in good agreement and thus support their identification.
PicoTesla magnetic tunneling junction sensors integrated with double staged magnetic flux concentrators
Authors: He Guanyang , Zhang Yiou , Qian Lijuan , Xiao Gang , Zhang Qiang , Santamarina J. Carlos , Patzek Tadeusz W. , Zhang Xixiang
Published: December 2018

Ultra-sensitive solid-state magnetic sensors are in strong demand in many applications where currently available sensors are inadequate. We have used high performance magnetic tunneling junction (MTJ) sensors and pushed the magnetic sensing limit to a high level. We have incorporated double-staged magnetic flux concentrators, one on the MTJ chip level and the other on a more macroscopic level, to amplify the external field of interest. With this approach and undergoing a process of optimization on the flux concentrators, we have increased the sensitivity of the MTJ sensor by a large factor of 517 to 775.4%/Oe in terms of magnetoresistance response. The coercivity of the sensor is only 0.12 Oe. We have achieved a detectable field limit of 30 pT/Hz at 10 kHz. We have presented the noise spectrum and the sensitivity spectrum up to a maximum frequency of 100 kHz.
Evaluation of bioink printability for bioprinting applications
Authors: Zhang Zhengyi , Jin Yifei , Yin Jun , Xu Changxue , Xiong Ruitong , Christensen Kyle , Ringeisen Bradley R. , Chrisey Douglas B. , Huang Yong
Published: December 2018

Three-dimensional (3D) bioprinting, as a freeform biomedical manufacturing approach, has been increasingly adopted for the fabrication of constructs analogous to living tissues. Generally, materials printed during 3D bioprinting are referred as bioinks, which may include living cells, extracellular matrix materials, cell media, and/or other additives. For 3D bioprinting to be an enabling tissue engineering approach, the bioink printability is a critical requirement as tissue constructs must be able to be printed and reproduce the complex micro-architecture of native tissues in vitro in sufficient resolution. The bioink printability is generally characterized in terms of the controllable formation of well-defined droplets/jets/filaments and/or the morphology and shape fidelity of deposited building blocks. This review presents a comprehensive overview of the studies of bioink printability during representative 3D bioprinting processes, including inkjet printing, laser printing, and micro-extrusion, with a focus on the understanding of the underlying physics during the formation of bioink-based features. A detailed discussion is conducted based on the typical time scales and dimensionless quantities for printability evaluation during bioprinting. For inkjet printing, the Z (the inverse of the Ohnesorge number), Weber, and capillary numbers have been employed for the construction of phase diagrams during the printing of Newtonian fluids, while the Weissenberg and Deborah numbers have been utilized during the printing of non-Newtonian bioinks. During laser printing of Newtonian solutions, the jettability can be characterized using the inverse of the Ohnesorge number, while Ohnesorge, elasto-capillary, and Weber numbers have been utilized to construct phase diagrams for typical non-Newtonian bioinks. For micro-extrusion, seven filament types have been identified including three types of well-defined filaments and four types of irregular filaments. During micro-extrusion, the Oldroyd number has been used to characterize the dimensions of the yielded areas of Herschel-Bulkley fluids. Non-ideal jetting behaviors are common during the droplet-based inkjet and laser printing processes due to the local nonuniformity and nonhomogeneity of cell-laden bioinks.
Impact of deep level defects induced by high energy neutron radiation in β-Ga2O3
Authors: Farzana Esmat , Chaiken Max F. , Blue Thomas E. , Arehart Aaron R. , Ringel Steven A.
Published: December 2018

The effects of high energy neutron irradiation on the deep level defect concentration profile throughout the bandgap of β-Ga2O3 were investigated by a combination of deep level optical spectroscopy (DLOS) and deep level transient spectroscopy (DLTS). For the unintentionally doped edge-defined film-fed growth-grown (010) β-Ga2O3 substrates investigated here, it was found that the dominant effects of neutron irradiation were to produce defects detected by DLOS having energy levels of EC −1.29 eV and EC −2.00 eV, with no discernable impact on traps within ∼1 eV of the conduction band edge. Commensurate with the introduction of these states was a significant amount of net doping reduction, for which lighted capacitance-voltage studies revealed that both of these irradiation-induced deep states are responsible, likely through a compensation mechanism. The sensitivity of the EC −1.29 eV and EC −2.00 eV states on irradiation suggests an intrinsic source, and whereas the EC −2.00 eV state was already present in the as-grown material, the EC −1.29 eV state was not detected prior to irradiation. DLOS and DLTS revealed other defect states at EC −0.63 eV, EC −0.81 eV, and EC −4.48 eV, but none of these responded to neutron irradiation for two different 1 MeV equivalent fluences 8.5 × 1014 cm−2 and 1.7 × 1015 cm−2, which is consistent with the behavior expected for defect states having an extrinsic source.
Structure modulation induced enhancement of microwave absorption in WS2 nanosheets
Authors: Ding W. , Hu L. , Liu Q. C. , Sheng Z. G. , Dai J. M. , Zhu X. B. , Sun Y. P.
Published: December 2018

This work reports the structural phase manipulation and the enhancement of microwave absorption in WS2 nanosheets. Large-scale WS2 nanosheets (1T@2H WS2) containing mixed 2H and 1T phases were synthesized by a simple hydrothermal process. The structural characteristics and concentration (∼60%) of the 1T phase in 1T@2H WS2 nanosheets were identified by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. With the emergence of the 1T phase, the permittivity of 1T@2H WS2 is more than three times higher than that of WS2 with a pure 2H phase (2H WS2). Moreover, the microwave absorption properties were remarkably enhanced due to the emergence of the 1T phase. Contrary to 2H WS2, in which microwave reflection loss (RL) is close to zero, the RL for 1T@2H WS2 can reach −47 dB with an effective bandwidth (<−10 dB) of 5.2 GHz. In addition, with the adjustment of the thickness of the absorber layer from 1.5 to 5 mm, 1T@2H WS2 can achieve strong absorption in a wide band from 4 to 18 GHz. This finding provides an effective strategy for designing and synthesizing the microwave absorption materials.
Perspective: Computational modeling of accurate cellular membranes with molecular resolution
Authors: Klauda Jeffery B.
Published: December 2018

Modeling lipid bilayers using molecular simulations has progressed from short simulations of single-component lipids to currently having the ability to model complex cellular membranes with nearly 100 different lipid types on a μs time scale. This perspective article presents a review of how the chemical physics field has provided insight into the structure and dynamics of accurate cellular membrane models. A short review of lipid force fields is presented, and how lower-resolution models can allow for assemblies and time scales not attainable with all-atom models. Key examples on membranes that mimic the lipid diversity seen in nature are provided for all-atom and coarse-grained lipid force fields. The article concludes with an outlook for the field on where there exist certain challenges (lipid diversity and leaflet concentration asymmetry) over the next several years. This is an exciting time to be a researcher in the field of modeling cellular membranes with ultimate goals to model not just an accurate cell membrane but in the future modeling a whole cell.
Substituent effect on the yield of unpaired electrons in DNA bases studied by electron paramagnetic resonance
Authors: Oka Toshitaka , Yokoya Akinari , Fujii Kentaro , Kino Yasushi , Sekine Tsutomu
Published: December 2018

The physicochemical processes underlying the radiation sensitization of DNA by the K-shell photoabsorption of nitrogen and oxygen atoms are unclear. Accordingly, we evaluated electron paramagnetic resonance spectra of thin films of pyrimidine bases. By altering the substituents of the pyrimidine ring, we found a substituent effect on the yield of unpaired electrons induced by photoabsorption. The yield of the unpaired electrons of the DNA-base containing amino groups increased by the donation of electrons, and the yield of halogenated DNA-bases decreased by the withdrawal of electrons. These different physicochemical processes might affect DNA bases, leading to differences in DNA modification.
Optimization of laser-driven cylindrical implosions on the OMEGA laser
Authors: Hansen E. C. , Barnak D. H. , Chang P.-Y. , Betti R. , Campbell E. M. , Davies J. R. , Knauer J. P. , Peebles J. L. , Regan S. P. , Sefkow A. B.
Published: December 2018

Laser-driven cylindrical implosions were conducted on the OMEGA laser as part of the laser-driven mini-MagLIF (Magnetized Liner Inertial Fusion) Campaign. Gated x-ray images were analyzed to infer shell trajectories and study the energy coupling in these implosions. Two-dimensional and three-dimensional HYDRA simulations were performed and post-processed to produce synthetic x-ray self-emission images for comparison. An analysis technique, which could be applied to both experimental and simulated x-ray images, was developed to characterize the shape and uniformity of the implosion. The analysis leads to a measurement of the average implosion velocity and axial implosion length, which can then be used to optimize the beam pointing and energy balance for future experiments. Discrepancies between simulation results and experiments allude to important physical processes that are not accounted for in the simulations. In 2-D simulations, the laser beam's azimuthal angle of incidence is not included because the ϕ-direction is not simulated, and thus, energy absorption is over-predicted. The 3-D simulation results are more consistent with the experiments, but the simulations do not include the calculation of cross-beam energy transfer or non-local thermal transport, which affects the energy coupled to the implosion. By appropriately adjusting the simulated energy balance and flux limit, the simulations can accurately model the experiments, which have achieved uniform implosions over a 700-μm-long region at velocities of approximately 200 km/s.
Detection of time reversibility in time series by ordinal patterns analysis
Authors: Martínez J. H. , Herrera-Diestra J. L. , Chavez M.
Published: December 2018

Time irreversibility is a common signature of nonlinear processes and a fundamental property of non-equilibrium systems driven by non-conservative forces. A time series is said to be reversible if its statistical properties are invariant regardless of the direction of time. Here, we propose the Time Reversibility from Ordinal Patterns method (TiROP) to assess time-reversibility from an observed finite time series. TiROP captures the information of scalar observations in time forward as well as its time-reversed counterpart by means of ordinal patterns. The method compares both underlying information contents by quantifying its (dis)-similarity via the Jensen-Shannon divergence. The statistic is contrasted with a population of divergences coming from a set of surrogates to unveil the temporal nature and its involved time scales. We tested TiROP in different synthetic and real, linear, and non-linear time series, juxtaposed with results from the classical Ramsey’s time reversibility test. Our results depict a novel, fast-computation, and fully data-driven methodology to assess time-reversibility with no further assumptions over data. This approach adds new insights into the current non-linear analysis techniques and also could shed light on determining new physiological biomarkers of high reliability and computational efficiency.
An efficient strategy to estimate thermodynamics and kinetics of G protein-coupled receptor activation using metadynamics and maximum caliber
Authors: Meral Derya , Provasi Davide , Filizola Marta
Published: December 2018

Computational strategies aimed at unveiling the thermodynamic and kinetic properties of G Protein-Coupled Receptor (GPCR) activation require extensive molecular dynamics simulations of the receptor embedded in an explicit lipid-water environment. A possible method for efficiently sampling the conformational space of such a complex system is metadynamics (MetaD) with path collective variables (CVs). Here, we applied well-tempered MetaD with path CVs to one of the few GPCRs for which both inactive and fully active experimental structures are available, the μ-opioid receptor (MOR), and assessed the ability of this enhanced sampling method to estimate the thermodynamic properties of receptor activation in line with those obtained by more computationally expensive adaptive sampling protocols. While n-body information theory analysis of these simulations confirmed that MetaD can efficiently characterize ligand-induced allosteric communication across the receptor, standard MetaD cannot be used directly to derive kinetic rates because transitions are accelerated by a bias potential. Applying the principle of Maximum Caliber (MaxCal) to the free-energy landscape of morphine-bound MOR reconstructed from MetaD, we obtained Markov state models that yield kinetic rates of MOR activation in agreement with those obtained by adaptive sampling. Taken together, these results suggest that the MetaD-MaxCal combination creates an efficient strategy for estimating the thermodynamic and kinetic properties of GPCR activation at an affordable computational cost.
Atomic-scale structure characteristics of antiferroelectric silver niobate
Authors: Li Gen , Liu Hai , Zhao Lei , Gao Jing , Li Jingfeng , Yu Rong , Zhu Jing
Published: December 2018

Antiferroelectric materials are a kind of functional material, which are widely used in electrostatic energy storage, energy conversion devices, and magnetoelectric coupling devices. As a typical lead-free antiferroelectric material, silver niobate has attracted much attention in recent years due to its excellent performance in energy storage. In this work, using the spherical aberration corrected electron microscopy technique, atomic-resolution images of pure silver niobate were obtained, which revealed typical microscopic physical characteristics of such complex antiferroelectric oxides: in such materials, all cations deviate from the average positions of the main lattice, and the displacement of each kind of cation varies periodically in two opposite directions, resulting in periodic wavy (1–10)c atomic planes, and the period of cation displacement is 15.6 Å. At the same time, the 90° antiferroelectric domain boundary and the antiphase domain wall defects are further revealed and analyzed.
Multi-channel tri-gate normally-on/off AlGaN/GaN MOSHEMTs on Si substrate with high breakdown voltage and low ON-resistance
Authors: Ma Jun , Erine Catherine , Xiang Peng , Cheng Kai , Matioli Elison
Published: December 2018

In this work, we present multi-channel tri-gate AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors (MOSHEMTs) for high-voltage applications. A heterostructure with multiple AlGaN/GaN layers was used to form five parallel two-dimensional-electron-gas (2DEG) channels to reduce the ON-resistance (RON), simultaneously modulated by the 3-dimensional tri-gate electrodes. The tri-gate is a unique technology to control the multi-channels, providing enhanced electrostatics and device performance, and, in turn, the multi-channels are exceptionally suited to address the degradation in drain current (ID,max) caused by the tri-gate. With a tri-gate width (w) of 100 nm, normally-on multi-channel tri-gate transistors presented 3×-higher maximum drain current (ID,max), 47%-smaller RON, as well as 79%-higher maximum transconductance (gm,max), as compared to counterpart single-channel devices. Using the channel depletion through the tri-gate sidewalls, normally-off operation was also achieved by reducing w below the sidewall depletion width (wdep), resulting in a positive threshold voltage (VTH) of 0.82 V at 1 μA/mm. The devices presented a high breakdown voltage (VBR) of 715 V, which reveals a promising future platform for high-voltage low-RON GaN transistors.