bluuebunny/crossref_metadata_2025 huggingface dataset:
How electrically evoked compound action potentials in chronically implanted guinea pigs relate to auditory nerve health and electrode impedance
Authors: Schvartz-Leyzac Kara C. , Colesa Deborah J. , Buswinka Christopher J. , Rabah Andrew M. , Swiderski Donald L. , Raphael Yehoash , Pfingst Bryan E.
Published: December 2020

This study examined how multiple measures based on the electrically evoked compound action potential (ECAP) amplitude-growth functions (AGFs) were related to estimates of neural [spiral ganglion neuron (SGN) density and cell size] and electrode impedance measures in 34 specific pathogen free pigmented guinea pigs that were chronically implanted (4.9–15.4 months) with a cochlear implant electrode array. Two interphase gaps (IPGs) were used for the biphasic pulses and the effect of the IPG on each ECAP measure was measured (“IPG effect”). When using a stimulus with a constant IPG, SGN density was related to the across-subject variance in ECAP AGF linear slope, peak amplitude, and N1 latency. The SGN density values also help to explain a significant proportion of variance in the IPG effect for AGF linear slope and peak amplitude measures. Regression modeling revealed that SGN density was the primary dependent variable contributing to across-subject variance for ECAP measures; SGN cell size did not significantly improve the fitting of the model. Results showed that simple impedance measures were weakly related to most ECAP measures but did not typically improve the fit of the regression model.
Universal relations for ultracold reactive molecules
Authors: He Mingyuan , Lv Chenwei , Lin Hai-Qing , Zhou Qi
Published: December 2020

There exist universal relations between the two-body loss in chemical reactions of ultracold molecules and many-body correlations.
Genetic Analysis of the Role of the Conserved Inner Membrane Protein CvpA in Enterohemorrhagic
Escherichia coli
Resistance to Deoxycholate
Authors: Warr Alyson R. , Giorgio Rachel T. , Waldor Matthew K.
Published: December 2020

Several enteric pathogens, including enterohemorrhagic
E. coli
(EHEC) strains, require CvpA to robustly colonize the intestine. This inner membrane protein is also important for secretion of a colicin and for EHEC resistance to the bile salt deoxycholate (DOC), but its function is unknown.
Travel time and perinatal mortality after emergency caesarean sections: an evaluation of the 2-hour proximity indicator in Sierra Leone
Authors: van Duinen Alex J , Adde Håvard A , Fredin Ola , Holmer Hampus , Hagander Lars , Koroma Alimamy P , Koroma Michael M , Leather Andrew JM , Wibe Arne , Bolkan Håkon A
Published: December 2020

Introduction

Longer travel times are associated with increased adverse maternal and perinatal outcomes. Geospatial modelling has been increasingly used to estimate geographic proximity in emergency obstetric care. In this study, we aimed to assess the correlation between modelled and patient-reported travel times and to evaluate its clinical relevance.

Methods

Women who delivered by caesarean section in nine hospitals were followed up with home visits at 1 month and 1 year. Travel times between the location before the delivery and the facility where caesarean section was performed were estimated, based on two models (model I Oumaet al; model II Munozet al). Patient-reported and modelled travel times were compared applying a univariable linear regression analysis, and the relation between travel time and perinatal mortality was assessed.

Results

The median reported travel time was 60 min, compared with 13 and 34 min estimated by the two models, respectively. The 2-hour access threshold correlated with a patient-reported travel time of 5.7 hours for model I and 1.8 hours for model II. Longer travel times were associated with transport by boat and ambulance, visiting one or two facilities before reaching the final facility, lower education and poverty. Lower perinatal mortality was found both in the group with a reported travel time of 2 hours or less (193 vs 308 per 1000 births, p<0.001) and a modelled travel time of 2 hours or less (model I: 209 vs 344 per 1000 births, p=0.003; model II: 181 vs 319 per 1000 births, p<0.001).

Conclusion

The standard model, used to estimate geographical proximity, consistently underestimated the travel time. However, the conservative travel time model corresponded better to patient-reported travel times. The 2-hour threshold as determined by the Lancet Commission on Global Surgery, is clinically relevant with respect to reducing perinatal death, not a clear cut-off.
Machine-learning-based hospital discharge predictions can support multidisciplinary rounds and decrease hospital length-of-stay
Authors: Levin Scott , Barnes Sean , Toerper Matthew , Debraine Arnaud , DeAngelo Anthony , Hamrock Eric , Hinson Jeremiah , Hoyer Erik , Dungarani Trushar , Howell Eric
Published: December 2020

Background

Patient flow directly affects quality of care, access and financial performance for hospitals. Multidisciplinary discharge-focused rounds have proven to minimise avoidable delays experienced by patients near discharge. The study objective was to support discharge-focused rounds by implementing a machine-learning-based discharge prediction model using real-time electronic health record (EHR) data. We aimed to evaluate model predictive performance and impact on hospital length-of-stay.

Methods

Discharge prediction models were developed from hospitalised patients on four inpatient units between April 2016 and September 2018. Unit-specific models were implemented to make individual patient predictions viewable with the EHR patient track board. Predictive performance was measured prospectively for 12 470 patients (120 780 patient-predictions) across all units. A pre/poststudy design applying interrupted time series methods was used to assess the impact of the discharge prediction model on hospital length-of-stay.

Results

Prospective discharge prediction performance ranged in area under the receiver operating characteristic curve from 0.70 to 0.80 for same-day and next-day predictions; sensitivity was between 0.63 and 0.83 and specificity between 0.48 and 0.80. Elapsed length-of-stay, counts of labs and medications, mobility assessments and measures of acute kidney injury were model features providing the most predictive value. Implementing the discharge predictions resulted in a reduction in hospital length-of-stay of over 12 hours on a medicine unit (p<0.001) and telemetry unit (p=0.002), while no changes were observed for the surgery unit (p=0.190) and second medicine unit (p<0.555).

Conclusions

Incorporating automated patient discharge predictions into multidisciplinary rounds can support decreases in hospital length-of-stay. Variation in execution and impact across inpatient units existed.
Effectiveness of workplace exercise interventions in the treatment of musculoskeletal disorders in office workers: a protocol of a systematic review
Authors: Tersa-Miralles Carlos , Pastells-Peiró Roland , Rubí-Carnacea Francesc , Bellon Filip , Rubinat Arnaldo Esther
Published: December 2020

Introduction

Physical inactivity due to changes in our society towards more sedentary behaviours is leading to health problems. Increasing physical activity might be a good strategy to improve physical strength and reduce the prevalence of illnesses associated with prolonged sitting. Office workers exhibit a sedentary lifestyle with short rest periods or even without pauses during the workday. It is important to perform workplace interventions to treat musculoskeletal disorders caused by prolonged sitting and lack of movement adopted on the office setting. This article describes a protocol for a systematic review to evaluate the effectiveness of exercise interventions on office workers in their work environment.

Methods and analysis

A literature search will be performed in the PubMed, CINAHL Plus, Cochrane Library, Scopus, ISI WoS and PeDRO databases for randomised controlled trials and studies published from 1 January 2010 to 31 July 2020 in English or Spanish. The participants will be office workers who spend most of their work time in a sitting position. The interventions performed will include any type of exercise intervention in the workplace. The outcome measures will vary in accordance with the aim of the intervention observed. The results of the review and the outcomes from the studies reviewed will be summarised with a narrative synthesis. The review protocol was developed according to the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols guidelines.

Ethics and dissemination

Ethical approval is not required. The review outcomes and the additional data obtained will be disseminated through publications and in scientific conferences.

PROSPERO registration number

CRD42020177462.
Cost-effectiveness of pembrolizumab for treatment of platinum-resistant recurrent or metastatic head and neck squamous cell carcinoma in China: an economic analysis based on a randomised, open-label, phase III trial
Authors: Xin Wenxiu , Ding Haiying , Fang Qilu , Zheng Xiaowei , Tong Yinghui , Xu Gaoqi , Yang Guonong
Published: December 2020

Background

Pembrolizumab was recently demonstrated to have survival benefit in patients with recurrent or metastatic head and neck squamous cell carcinoma (r/mHNSCC). However, the cost-effectiveness of pembrolizumab versus chemotherapy in China remains uncertain.

Objective

This analysis aimed to describe the cost-effectiveness of pembrolizumab versus standard-of-care (SOC) therapy in r/mHNSCC in China.

Design

A Markov model consisting of three health states (stable, progressive and dead) was developed to compare the cost and effectiveness of pembrolizumab with SOC in platinum-resistant r/mHNSCC. Model inputs for transition probabilities and toxicity were collected from the KEYNOTE-040 trial, while health utilities were estimated from a literature review. Cost data were acquired for the payer’s perspective in China. Costs and outcomes were discounted at an annual rate of 3.0%. Sensitivity analyses were conducted to test the uncertainties surrounding model parameters.

Outcome measures

The primary outcome was incremental cost-effectiveness ratios (ICERs), which were calculated as the cost per quality-adjusted life years (QALYs).

Results

The total mean cost of pembrolizumab and SOC was US$45 861 and US$41 950, respectively. As for effectiveness, pembrolizumab yielded 0.31 QALYs compared with 0.25 QALYs for SOC therapy. The ICER for pembrolizumab versus SOC was US$65 186/QALY, which was higher than the willingness-to-pay threshold (WTP) of US$28 130/QALY in China. The univariate sensitivity analysis indicated that utility values for progressive state, probability from stable to progressive in the SOC group, as well as cost of pembrolizumab were the three most influential variables on ICER. The probabilistic sensitivity analysis demonstrated that standard therapy was more likely to be cost-effective compared with pembrolizumab at a WTP value of US$28 130/QALY. Results were robust across both univariate analysis and probabilistic sensitivity analysis.

Conclusions

Pembrolizumab is not likely to be a cost-effective strategy compared with SOC therapy in patients with platinum-resistant r/mHNSCC in China.

Trial registration number

NCT02252042; Post-results.
How to improve emergency care to adults discharged within 24 hours? Acute Care planning in Emergency departments (The ACE study): a protocol of a participatory design study
Authors: Østervang Christina , Lassen Annmarie Touborg , Jensen Charlotte Myhre , Coyne Elisabeth , Dieperink Karin Brochstedt
Published: December 2020

Introduction

The development of acute symptoms or changes in diseases led to feelings of fear and vulnerability and the need for health professional support. Therefore, the care provided in the acute medical and surgical areas of the emergency department (ED) is highly important as it influences the confidence of patients and families in managing everyday life after discharge. There is an increase in short-episode (<24 hours) hospital admissions, related to demographic changes and a focus on outpatient care. Clear discharge information and inclusion in treatment decisions increase the patient’s and family’s ability to understand and manage health needs after discharge, reduces the risk of readmission. This study aims to identify the needs for ED care and develop a solution to improve outcomes of patients discharged within 24 hours of admission.

Methods and analysis

The study comprises the three phases of a participatory design (PD). Phase 1 aims to understand and identify patient and family needs when discharged within 24 hours of admission. A qualitative observational study will be conducted in two different EDs, followed by 20 joint interviews with patients and their families. Four focus group interviews with healthcare professionals will provide understanding of the short pathways. Findings from phase 1 will inform phase 2, which aims to develop a solution to improve patient outcomes. Three workshops gathering relevant stakeholders are arranged in the design plus development of a solution with specific outcomes. The solution will be implemented and tested in phase 3. Here we report the study protocol of phase 1 and 2.

Ethics and dissemination

The study is registered with the Danish Data Protection Agency (19/22672). Approval of the project has been granted by the Regional Committees on Health Research Ethics for Southern Denmark (S-20192000–111). Findings will be published in suitable international journals and disseminated through conferences.
Assessing the changes in childbirth care practices and neonatal outcomes in Western China: pre-comparison and post-comparison study on early essential newborn care interventions
Authors: Qu Wen , Yue Qing , Wang Yan , Yang Jin Liuxing , Jin Xi , Huang Xiaona , Tian Xiaobo , Martin Kathryn , Narayan Anuradha , Xu Tao
Published: December 2020

Objective

To explore the changes in childbirth care practices and health outcomes of newborns after the introduction of early essential newborn care (EENC).

Design

A pre-comparison and post-comparison study.

Setting

The study was conducted in December 2016 and December 2018 in 18 counties in four western provinces of China.

Participants

46 hospitals that provide delivery services participated in the study.

Interventions

EENC practices were introduced and implemented in the 46 hospitals.

Outcome measures

The changes of hospital indicators such as incidence of birth asphyxia and neonatal mortality were compared in 2016 and 2018. EENC coverage indicators, such as skin-to-skin (STS) contact, and time of first breast feeding were also compared before and after the intervention via interview with 524 randomly selected postpartum mothers (320 in 2016 and 204 in 2018).

Results

54 335 newborns were delivered in the pre-EENC period (2016) and 58 057 delivered in the post-EENC period (2018). According to hospital records, the proportion of newborns receiving immediate STS contact increased from 32.6% to 51.2% (Risk Ratio (RR)=1.57,95% CI 1.55 to 1.59) and the percentage of newborns receiving prolonged STS contact for more than 90 min increased from 8.1% to 26.8% (RR=3.31, 95% CI 3.21 to 3.41). No statistically significant changes were found in neonatal mortality, although slight decreases in birth asphyxiate and neonatal intensive care unit admission rates were detected. Among the mothers interviewed, the proportion of newborns receiving immediate STS contact increased from 34.6% to 80.0% (RR=2.31, 95% CI 1.69 to 3.17). The exclusive breastfeeding rate increased from 43% to 73.4% (RR=1.71, 95% CI 1.43 to 2.04). The average length of the first breast feeding increased from 15.8 min to 17.1 min.

Conclusions

The introduction of EENC has yielded significant improvements in newborn care services at the pilot hospitals, including enhanced maternal and newborn care practices, improved STS contact quality and early breastfeeding performance. Further studies are needed to evaluate the long-term impact of EENC on newborn health outcomes.
Implementing large-system, value-based healthcare initiatives: a realist study protocol for seven natural experiments
Authors: Sarkies Mitchell N , Francis-Auton Emilie , Long Janet C , Partington Andrew , Pomare Chiara , Nguyen Hoa Mi , Wu Wendy , Westbrook Johanna , Day Richard O , Levesque Jean-Frederic , Mitchell Rebecca , Rapport Frances , Cutler Henry , Tran Yvonne , Clay-Williams Robyn , Watson Diane E , Arnolda Gaston , Hibbert Peter D , Lystad Reidar , Mumford Virginia , Leipnik George , Sutherland Kim , Hardwick Rebecca , Braithwaite Jeffrey
Published: December 2020

Introduction

Value-based healthcare delivery models have emerged to address the unprecedented pressure on long-term health system performance and sustainability and to respond to the changing needs and expectations of patients. Implementing and scaling the benefits from these care delivery models to achieve large-system transformation are challenging and require consideration of complexity and context. Realist studies enable researchers to explore factors beyond ‘what works’ towards more nuanced understanding of ‘what tends to work for whom under which circumstances’. This research proposes a realist study of the implementation approach for seven large-system, value-based healthcare initiatives in New South Wales, Australia, to elucidate how different implementation strategies and processes stimulate the uptake, adoption, fidelity and adherence of initiatives to achieve sustainable impacts across a variety of contexts.

Methods and analysis

This exploratory, sequential, mixed methods realist study followed RAMESES II (Realist And Meta-narrative Evidence Syntheses: Evolving Standards) reporting standards for realist studies. Stage 1 will formulate initial programme theories from review of existing literature, analysis of programme documents and qualitative interviews with programme designers, implementation support staff and evaluators. Stage 2 envisages testing and refining these hypothesised programme theories through qualitative interviews with local hospital network staff running initiatives, and analyses of quantitative data from the programme evaluation, hospital administrative systems and an implementation outcome survey. Stage 3 proposes to produce generalisable middle-range theories by synthesising data from context–mechanism–outcome configurations across initiatives. Qualitative data will be analysed retroductively and quantitative data will be analysed to identify relationships between the implementation strategies and processes, and implementation and programme outcomes. Mixed methods triangulation will be performed.

Ethics and dissemination

Ethical approval has been granted by Macquarie University (Project ID 23816) and Hunter New England (Project ID 2020/ETH02186) Human Research Ethics Committees. The findings will be published in peer-reviewed journals. Results will be fed back to partner organisations and roundtable discussions with other health jurisdictions will be held, to share learnings.
China’s Rail Infrastructure On Track to Go Global
Authors: DARKE Walker
Published: December 2020

Alongside China’s sustained investment in domestic rail infrastructure, rail transport has become one of many infrastructural services on the menu for prospective international partners of the Belt and Road Initiative. This article undertakes a study of press and media reports from across the globe exploring China’s impact on rail infrastructure outside China. It highlights China’s truly global reach in rail through various means and the key political, economic and cultural motivations.
High-Performance Organometallic Catalyst Based on Nickel Porphyrin/Carbon Fibre for the Oxygen Reduction Reaction
Authors: Elghamry Ibrahim , Alablan Abdulrahman S. , Alkhalifah Mohammed A. , Abdelsalam Mamdouh E.
Published: December 2020

Development of efficient non-precious metals catalysts for the oxygen reduction reaction (ORR) has attracted considerable attention. A composite catalyst based on nickel- 5,10,15,20-tetra(p-thioanisole) porphyrin complex (Ni-TPT-P) and carbon fibres (CF) is here investigated for the ORR. The porphyrin is synthesised by a one-pot multi-step approach. Ultraviolet-visible (UV–vis) and fourier-transform infrared (FTIR) techniques are used to confirm the synthesis of the Ni-TPT-P complex. The metalloporphyrins (Ni-TPT-P) are non-covalently adsorbed on the CF via

π
−
π

stacking interaction. The composite catalyst shows well-defined redox peaks attributed to the Ni2+/Ni3+ redox couple in O2-saturated 0.1 M KOH solution. The area under the reduction peak is used to calculate a surface coverage (

Г

) of 2.43 × 1015 for the Ni2+/Ni3+ species on the catalyst surface area. The rotating ring disk electrode (RRDE) technique is used to assess the performance of the catalyst towards the ORR. Key performance indicators such as the onset potential, average number of electrons and

HO

2

−

yield are found to be, 0.82 V vs RHE, 3.6 electrons and 22.0% respectively.
Measurement of Volume Changes and Associated Stresses in Ge Electrodes Due to Na/Na+ Redox Reactions
Authors: Rakshit Subhajit , Pakhare Akshay S. , Ruiz Olivia , Khoshi M. Reza , Detsi Eric , He Huixin , Sethuraman Vijay A. , Nadimpalli Siva P. V.
Published: December 2020

In situ electrochemical cells were assembled with an amorphous germanium (a-Ge) film as working electrode and sodium foil as reference and counter electrode. The stresses generated in a-Ge electrodes due to electrochemical reaction with sodium were measured in real-time during the galvanostatic cycling. A specially designed patterned a-Ge electrode was cycled against sodium and the corresponding volume changes were measured using an AFM; it was observed that sodiation/desodiation of a-Ge results in more than 300% volume change, consistent with literature. The potential and stress response showed that the a-Ge film undergoes irreversible changes during the first sodiation process, but the subsequent desodiation/sodiation cycles are reversible. The stress response of the film reached steady-state after the initial sodiation and is qualitatively similar to the response of Ge during lithiation, i.e., initial linear elastic response followed by extensive plastic deformation of the film to accommodate large volume changes. However, despite being bigger ion, sodiation of Ge generated lower stress levels compared to lithiation. Consequently, the mechanical dissipation losses associated with plastic deformation are lower during sodiation process than it is for lithiation.
Fast Charging of Li-Ion Cells: Part V. Design and Demonstration of Protocols to Avoid Li-Plating
Authors: Shkrob Ilya A. , Rodrigues Marco-Tulio F. , Abraham Daniel P.
Published: December 2020

Fast charging of Li-ion batteries would make “fueling” of electric vehicles comparable in time to fueling of gasoline-powered cars, increasing consumer appeal of the new technology. Taking the US Department of Energy goal of safe 6 C charging to 80% capacity as a guide, we describe approaches that can mitigate Li plating on the graphite anode. To make this possible, a variable-rate anode potential charging protocol has been implemented by using a microprobe reference electrode to continuously monitor and adjust the current, in this way avoiding low anode potentials that favor Li deposition. Various implementations of the anode potential control are considered using electrochemical modeling and compared with the experimental data. For charge to 80% capacity at 30 °C, an average C-rate of 4.97 C was obtained for an NCM523/graphite cell with 70 μm thick graphite electrode and 7.40 C for a cell with 47 μm thick graphite electrode. Our electrochemical model accounts for these observations and provides a means to extrapolate the approach to other cell designs and operation regimes, drawing the maximum average fast charging rates that can still avoid Li plating.
Inorganic-Shell Reinforcement: TiO2-Coated Polyimide Nanofibers Membrane as Advanced Separator for Lithium-Ion Batteries
Authors: Dong Nanxi , Wang Jie , Tian Guofeng , Qi Shengli , Sun Guohua , Wu Dezhen
Published: December 2020

Herein, we report a series of titania (TiO2)-coated polymeric nanofibers membranes with superb strength, excellent thermal stability, and admirable wettability via in situ coating TiO2 nano-shells on the surface of polyimide (PI) nanofibers. TiO2 nano-shells are able to weld the PI nanofibers and serve as a reinforcement layer, endowing the TiO2-coated PI separator with high tensile strength of 43.94 MPa. Specifically, the in situ coating technique is a simple and controllable method to fabricate high-performance hybrid separator and meet the demand of low-cost industrial production. Moreover, TiO2-coated PI separator displays preferable wettability, thermal stability, and ion conductivity than the Celgard separator. Importantly, the unique thermal dimensional stability of TiO2-nanoshells and PI materials also improves the safety of lithium ion battery (LIB). Notably, TiO2-coated PI separator exhibit superior LIB capability of 140.1 mAh g−1 at 5 C compared to the commercial Celgard separator (95.4 mAh g−1, 5 C). Besides, the present battery with TiO2-coated PI separator can operate stably after being tested at 1 C for 100 cycles. Thus, we believe that this work provides a significant contribution for realizing industrial production preparation of high-performance hybrid separators for LIBs.
From the Editor: Scaling the Heights
Authors: Rajeshwar Krishnan
Published: December 2020

Another year has come and gone and the reflective mood that sets in toward the end of each year is slowly fading as I sit down to write this column in February.
From the Editor: Red, Blue, or Green?
Authors: Rajeshwar Krishnan
Published: December 2020

I am writing this column during the home stretch of the presidential election year in the U.S. Notwithstanding the election-year hype and policy differences (e.g., off-shore drilling, nuclear power), both sides of the political spectrum are remarkably like-minded in their approach to energy and the environment.
From the President: The Benefits of Membership
Authors: Buckley Noel
Published: December 2020

Member benefits are a cornerstone of our Society. These have changed over the years in response to changes in the needs of members, changes in the format of publications, and other trends in the activities of the Society.
Organic and Bioelectrochemistry: New Directions, Bright Prospects
Authors: Fry Albert
Published: December 2020

I am honored and delighted to have the opportunity to be guest editor of this issue of Interface, devoted to organic and biological electrochemistry. As I have discussed in my article in this issue, organic electrochemistry entered a period of intense growth in the mid-1960s, which I have traced to the simultaneous development around that time of new instrumental techniques, theoretical developments (such as the ability to simulate complex reaction mechanisms), and the entry of a large number of highly productive individuals into the area.
The Chalkboard: Basics of Lighting: Efficacy, Color Rendering, and Color Temperature
Authors: Happek Uwe
Published: December 2020

If you are environmentally conscious, or simply thrifty, you probably would have replaced your incandescent lamps (the Edison type) with more efficient devices. (If you happen to live in Europe, you cannot even buy the incandescent any more!) What you are looking for when deciding on a new lamp is the “luminous efficacy,” measured in lumens/watt.
Size Does Matter: Autonomous Micro-Power Sources
Authors: Takeuchi Esther
Published: December 2020

It is indeed a pleasure to be guest editor of this issue of Interface and have the opportunity to shed some light on the relationship of power and size. Remarkable advances have taken place in the ability to construct electronic devices, sensors, and even mechanical systems at the micro scale.
Metal Corrosion in the Human Body: The Ultimate Bio-Corrosion Scenario
Authors: Hansen Douglas C.
Published: December 2020

It is not something one usually thinks about until it becomes a personal health issue for most of us. That is, the need for the implantation of a medical device (Fig. 1) to improve our existing medical condition. The majority of these devices are made of a metal alloy, and for most of us, any concerns about corrosion implications from these implants are secondary to the relief we feel from the anticipated beneficial effect these devices are designed to have.
Nanostructured Carbons: Double-Layer Capacitance and More
Authors: Simon Patrice , Burke Andrew
Published: December 2020

This article is concerned with the design and characteristics of electrochemical double layer capacitors (EDLCs), and in particular the role of nanostructured carbons and how they function.
Organic Electrochemistry, Microreactors, and Their Synergy
Authors: Yoshida Jun-ichi
Published: December 2020

Driven by remarkable improvements in our understanding of factors governing organic reactions, the role of organic synthesis has been expanded to various fields of science and technology, such as new materials and new medicinal agents.
Hybrid Supplies for Wireless Micro-Systems
Authors: Torres Erick O. , Milner Luke , Rincón-Mora Gabriel A.
Published: December 2020

Ultra-compact micro-electronic devices like wireless microsensors provide sensing and monitoring functions to a wide variety of applications in medicine, industry, and the military. Because of their diminutive micro-scale dimensions, these micro-systems are unobtrusive and can be deployed in numerous quantities as a network gathering information from typically inaccessible environments, such as inside the human body.
JES Classics: ECS Science at Its Best: Perspectives on Newman’s Work on Resistance for Flow of Current to a Disk
Authors: Orazem Mark E. , Tribollet Bernard
Published: December 2020

In the late 1960s, John Newman began publishing a series of papers on the electrical characteristics of a disk electrode embedded in a semi-infinite insulating plane. His work revealed the influence that nonuniform current distributions have on experimental measurements obtained with the rotating disk electrode, commonly used in the electrochemical community.
JES Classics: ECS Science at Its Best: Polarization Curves Demystified
Authors: Zawodzinski Thomas A.
Published: December 2020

It is occasionally the case that certain types of work produce results that seem completely obvious in hindsight. A common example of a case where this effect is observed is for papers that provide a synthesis of several ideas. The elegance, simplicity, and power of such analyses, while critical to the consolidation of scientific ideas, leads us to forget the state of confusion or piecemeal understanding that existed prior to their elaboration.
JES Classics: ECS Science at Its Best: A Perspective on Electrochemical Impedance Analysis of Polyaniline Films on Electrodes
Authors: Lvovich Vadim F.
Published: December 2020

During the past two decades, extensive studies of conductive polymers have been driven by their special properties, such as flexible solution and melt processability manufacturing, blendability with commodity polymers, good ambient stability, and unconventional electrical and optical properties.
Selective Corrosion and Solidification Microstructure of Laser Powder Bed Fusion 316L Stainless Steel
Authors: Macatangay Duane Armell , Conrades Jenna , Brunner Keegan , Kelly Robert
Published: December 2020

The recent growth in additive manufacturing (AM) has fueled the motivation to understand the properties and performance of conventional alloys that have been synthesized through these methods. Laser powder bed fusion (LPBF) is a form of AM that uses high energy lasers to construct bulk materials from the melting and rapid solidification of powder on a layer-by-layer basis. While there has been considerable work done to optimize LPBF processing parameters for various metallic alloys and characterize the resulting microstructure and mechanical properties, little work has been performed to characterize the corrosion properties of these 3-D printed alloys.

316L is an austenitic stainless steel that is utilized in various applications due to its excellent mechanical properties and corrosion resistance. Although wrought 316L has a signature microstructure that is nominally single phase and made up of equiaxed grains, the additive process introduces a non-equilibrium microstructure. This leads to the introduction of compositional heterogeneities via melt pool boundaries and cellular structures and provide an origin for selective corrosion, leading to potential issues involving the longevity of these alloys in the as-printed state.

Sensitization occurs in stainless steels through the intergranular precipitation of chromium carbides at grain boundaries when the material is exposed to temperature ranges of 450 – 800 °C. This leads to the depletion of chromium at regions adjacent to grain boundaries and may lead to intergranular corrosion and intergranular stress corrosion cracking. The utilization of post-processing methods such as hot isotactic pressing induces temperatures within this range and may initiate this solid-solid phase transformation. The observation of accelerated sensitization in LPBF 316L provides motivation to characterize and understand this sensitization behavior.

This study explores corrosion in LPBF 316L with attention to melt pool boundary dissolution and intergranular corrosion. This study also acknowledges the effect of processing parameters on the resulting microstructure and corrosion behavior. Galvanostatic etching and potentiodynamic polarization are performed to quantify and understand the electrochemical behavior of these alloys. Characterization methods such as scanning electron microscopy and white light interferometry are used to probe the microstructure and corrosion morphology of these alloys in comparison to the conventionally wrought counterpart.
Ordered Macroporous Photonic Crystal Hot Electron Plasmonic Photocatalysts
Authors: Collins Gillian , Lonergan Alex , McNulty David , Glynn Colm , Buckley Darragh , Hu Changyu , O'Dwyer Colm
Published: December 2020

Plasmon-enhanced photocatalysis provides opportunities for controlling chemical reaction rates, especially when the influence of the light is to enhance or alter charge transfer properties. Semiconductor photocatalysts with an inverse opal or photonic crystal structure not only provide large, open and accessible surface area, they are electrically interconnected as a porous network. This becomes a useful scaffold to dock metallic nanoparticles whose size can be tuned to absorb specific frequencies resonant with their localised surface plasmon resonance. Coupling this with the nature of the metal-semiconductor band structure (where the metal oxide is wide band gap) and exploiting certain properties of photonic crystals, more efficient photocatalysts are possible. We demonstrate semiconducting photonic crystal plasmonic photocatalysts using V2O5 and TiO2 as visible light semiconductor catalysts that showed superior performance to a conventional TiO2 support for hydrogenation of 4-nitrophenol. The approach married the photonic band gap, metal oxide semiconductor bandgap, slow photon effect and localised surface plasmon polaritons to maximum photon absorption to modulate charge transfer and electron density either in the metal nanoparticle, or the conduction band of the semiconductor to give a better photocatalyst.

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Figure 1. V2O5 3D macroporous inverse opal photonic crystal decorated with Au nanoparticles.

Figure 1
(Invited) Porous Structure Produced By Metal-Assisted Etching of Silicon
Authors: Yae Shinji , Matsumoto Ayumu
Published: December 2020

Metal-assisted etching of silicon can produce porous silicon and silicon nanowires by simply immersing metal-modified silicon in a hydrofluoric acid solution without electrical bias [1]. Such etching proceeds by a local galvanic cell mechanism consisting of local anodic dissolution of silicon and local cathodic reduction of an oxidizing agent, such as oxygen [2, 3] or hydrogen peroxide, on catalytic metal. The structure of porous silicon is widely controlled from nanometer to sub-millimeter scale in pore size and from straight to an ants’ nest like in pore morphology by changing etching conditions [1-3]. We fabricate various porous structures on silicon wafers, and apply them to antireflection of solar cells and autocatalytic electroless formation of metal-nanorods and metal films on silicon surfaces. The structure of porous silicon is easily controlled in the nanometer scale with changing etching conditions such as kind, size, and distribution of metal catalysts, kind and concentration of oxidizing agent, intensity of photoillumination, and etching time. Recently, we found that general corrosion occurred on the top surface of the silicon substrate around the metal particles even under the dark condition [4]. The general corrosion depended on the metal species and it was explained by the formation and dissolution of a mesoporous layer.

[1] Z. Huang, N. Geyer, P. Werner, and U. Gösele, Adv. Mater., 23, 285 (2011).

[2] S. Yae, Y. Kawamoto, H. Tanaka, N. Fukumuro, and H. Matsuda, Electrochem. Comm., 5, 632 (2003).

[3] S. Yae, M. Tashiro, M. Abe, N. Fukumuro, H. Matsuda, J. Electrochem. Soc., 157, D90 (2010).

[4] A. Matsumoto, H. Son, M. Eguchi, K. Iwamoto, Y. Shimada, K. Furukawa, and S. Yae, RSC Adv., 10, 253 (2020).
(Invited) Anodization of Al in Neutral Oxalate Solution to Form Fine Nanoporous Film
Authors: Nishio Kazuyuki
Published: December 2020

Anodic porous alumina has been widely used as an oxide coating of Al surfaces. Recently, fine and deep nanoporous structures are studied for use as novel templates in various applications. Highly ordered porous alumina is obtained by long-time anodization under appropriate conditions. Typically, hexagonally arranged nanopores with an interpore distance of 100 nm are formed in oxalic acid at 40 V.1 Here, we describe the formation of finer porous alumina (interpore distance of ~25 nm) by anodization in a potassium oxalate solution at 40 V. There have been a few reports on the formation of fine pores in boric acid and borate solutions under hot conditions.2-4 It is thought that the increase in the solubility of the oxide film in the hot borate electrolyte results in the growth of fine pores. However, in the case of anodization in a neutral oxalate solution, a fine nanoporous film was formed in a wide range of temperatures (0-85 °C).

Figure 1 (left) shows the results of Al anodization in 0.20 M potassium oxalate (pH 7.6) at 40 V vs Hg/Hg2SO4 for 6 h at 25 °C. The current gradually increased to ~0.4 mAcm-2 in 40 min then gradually decreased. After anodization for 2 h, the current reached a low value and remained at ~0.1 mAcm-2. As shown in the figure, the voltage between the working and counter electrodes remained at 41.7 V. Figure 2 (right) shows a cross-sectional SEM image of the obtained oxide film. Since the interpore distance of anodic porous alumina formed in conventional oxalic acid at 40 V is 100 nm (scale length in Fig. 2), the image clearly indicates that the pores are unusually fine. It is also confirmed that the oxide film is composed of following three layers: an upper porous layer that contains large pores, a lower porous layer with fine and straight pores and a flat barrier layer with a thickness of ~60 nm. The total thickness of the oxide film was 440 nm. It was also confirmed that the growth of nanopores terminates when the anodic current decreases from its peak to a low value.5

References

(1) H. Masuda, K Fukuda, Science, 268, 1466 (1995).

(2) G. A. Dorsey Jr., J. Electrochem. Soc.
1969, 116, 466.

(3) J. S. L. Leach, P. Neufeld, Corros. Sci.
1969, 9, 413.

(4) H. Takahashi, M. Nagayama, Electrochim. Acta
1978, 23, 279.

(5) K. Nishio, R. Sasaki, Chem. Lett., 2019, 48, 1126.

Figure 1
(Invited) Self-Activation of TiO2 Nanotubes for Photocatalytic H2 Generation
Authors: Schmuki Patrik
Published: December 2020

TiO2 and particularly its anatase form, is one of the most widely studied oxide semiconductors for photocatalytic production of H2 from aqueous solutions.In anatase, the conduction band is situated at an energetic position that allows the transfer of photogenerated electrons to aqueous media and thus the conversion of H+ into H2. Moreover, TiO2 provides an almost unique high resistance against chemical and photocorrosion. On the other hand, photocatalytic H2 production from aqueous electrolytes shows very slow kinetics on all TiO2 surfaces. Therefore, typically decoration of titania with co-catalysts is used to accelerate the H2 evolution kinetics. Most effective co-catalysts are costly noble metals, such as Pt, Pd, or Au. Economically it is of great interest to develop means and approaches to reduce the use of such costly co-catalyst. In the presentation, we discuss efficient noble-metal-free approaches for catalyzing photocatalytic hydrogen generation. A particularly interesting approach is provided by defined defect engineering of anatase. Specific shallow Ti3+ states can promote the generation of photocatalytic H2. Most spectacular is that these catalytic sites can be formed by photoinduced reduction. In other words, under suitable illumination conditions it is possible to create, in situ, energetically suitable Ti3+ states that then act as an intrinsic co-catalyst for photocatalytic H2 evolution. As a result, both co-catalytic formation of active sites and photocatalytic H2 formation is observed. I.e. with increasing illumination time, a light‐induced self‐amplification of the photocatalytic H2 production rate occurs. The effect is characterized by electron paramagnetic resonance (EPR) spectroscopy, reflectivity, and photoelectrochemical techniques. The origin of the self‐activation and amplification behavior observed for anatase nanoparticles and anodically grown self-organized TiO2 nanotube structures will be discussed in the presentation.
Similarity and Difference in the Plating Pretreatment for Mg and Al Alloys
Authors: Azumi Kazuhisa , Ikeda Kazuki , Watanabe Junpei , Yamamoto Hiroyuki
Published: December 2020

Mg and Al are light-weight less-noble metals and are expected as a key material for potential applications in the fields of transportation to save energy. Especially for Mg alloys, the addition of corrosion resistance is essentially important for outside use. Plating has been used to provide various functionalities to metals such as good appearance, wear resistance, sliding performance, wettability or repellency, and corrosion resistance. Both Mg and Al have similar difficulty in the plating process because the surface of metals is always covered with the passive film (Al) or corrosion film (Mg) that prevents the plating process as the electron transfer and the metal-to-metal bonding. In the plating process, therefore, such surface films should be removed before or during the treatment process. The zincate pretreatment has been applied to these metals in which the surface was replaced with Zn layer that provides a good substrate for the subsequent plating process. In the zincate process, Al or Mg surface is dissolved, and Zn is deposited simultaneously by the substitution reaction in the zincate bath containing Zn(II) ions to cover the substrate. In the case of Al, this substitution reaction proceeds rapidly, and the substrate surface is almost completely covered with Zn layer. In the case of Mg, however, the coverage with Zn is more important than Al because Mg can be rapidly dissolved in the zincating bath. Excess dissolution of Mg substrate causes the undesired poor adhesion of the plating film to the substrate. Therefore, the zincating condition for Mg alloys should be optimized to take a balance between the Mg dissolution and the substitutional deposition of Zn.

On the other hand, a complicated structure composed of the area where dense pillars are formed and a bank surrounding this area is sometimes found on AZ31 alloy after the zincate treatment, as shown in Fig. 1. Such a structure is formed by the combination of the continuous dissolution of Mg substrate and the local deposition of Zn that protects Mg substrate from the dissolution. A bank is formed on the grain boundary of AZ31 surface, where initial Zn deposition preferentially proceeded. Such micro-structure can be compared with a well-known ordered porous alumina film formed on Al by the dynamic process of the continuous growth of anodic oxide film and mass transportation of ions in the growing film.

Figure 1
Modified Silicon Nanoparticles As an Anode for Lithium-Ion Batteries
Authors: Nurpeissova Arailym , Abilmazhinova Dana , Mukanova Aliya , Bakenov Zhumabay
Published: December 2020

Due to the outstanding electrochemical properties, lithium-ion batteries have become a widely used energy storage technology for diverse types of devices. However, rapid progress in portable electronic devices and electric vehicles requires further essential improvement in the power and energy densities of lithium-ion batteries (LIBs) [1]. Conventional LIBs technology has reached the limit of its gravimetric / volumetric energy densities and power capabilities, reducing its ability to power new electronic devices and / or work as large batteries.

Among the promising candidates for anode materials, silicon (Si) has several advantages, including high theoretical capacity, low reaction potential against cathode material, environmental compatibility, low toxicity, and low cost. However, for the practical implementation of Si anodes in LIBs, it is necessary to consider one big critical issue: adaptation of large volume changes. Significant change in volume (4300%) during lithiation / delitration, leads to the volume expansion and grinding of Si particles, which leads to a rapid loss of electrode capacity, as shown in Figure 1a.

Figure 1. Schematic representation of volume expansion of Si anode (a) and suppression of volume expansion in modified Si anode (b)

This work presents the development of a new technology for the preparation of a composite anode material based on spinel Li4Ti5O12 (LTO) and Si with the addition of polyacrylonitrile (PAN) by liquid-phase coating, which demonstrates a synergistic positive effect on the performance of Si anodes (Fig. 1b). The idea lies in the coating the surface of silicon particles with LTO and PAN to suppress the volume expansion and improve the conductivity. The unique structure of LTO with zero deformation during lithiation / delitiation will help to withstand the volume change whereas PAN coating will improve the conductivity of the whole system.

Acknowledgements

This work was supported by projects AP05133706 “Innovative high-capacity anodes based on lithium titanate for a next generation of batteries” from the Ministry of Education and Science of the Republic of Kazakhstan and 091019CRP2114 “Three-Dimensional All Solid State Rechargeable Batteries” from Nazarbayev University.

References:

[1] J.M. Tarascon, M. Armand, Issues and challenges facing rechargeable lithium batteries, Nature. 414 (2001) 359–67. https://doi.org/10.1038/35104644

Figure 1