Catalytic Dehydrogenation of Formic Acid Promoted by Triphos-Co Complexes: Two Competing Pathways for H2 Production.

In this study, we reported the synthesis and structural characterization of a triphos-CoII complex [(κ3-triphos)CoII(CH3CN)2]2+ (1) and a triphos-CoI-H complex [(κ2-triphos)HCoI(CO)2] (4). The facile synthetic pathways from 1 to [(κ3-triphos)CoII(κ2-O2CH)]+ (1') and [(κ3-triphos)CoI(CH3CN)]+ (2), respectively, as well as the interconversion between [(κ3-triphos)CoI(CO)2]+ (3) and 4 have been established. The activation energy barrier, associated with the dehydrogenation of a coordinated formate fragment in 1' yielding the corresponding 2 accompanied by the formation of H2 and CO2, was experimentally determined as 23.9 kcal/mol. With 0.01 mol % loading of 1, a maximum TON ∼ 1735 within 18 h and TOF ∼ 483 h-1 for the first 3 h could be achieved. Kinetic isotope effect (KIE) values of 2.25 (kHCOOH/kDCOOH) and 1.36 (kHCOOH/kHCOOD) for the dehydrogenation of formic acid and its deuterated derivatives, respectively, implicate that the H-COOH bond cleavage is likely the rate-determining step. The catalytic mechanism proposed by density functional theory (DFT) calculations coupled with experimental 1H NMR and gas chromatography-mass spectrometry (GC-MS) analysis unveils two competing pathways for H2 production; specifically, deprotonating a HCOO-H bond by a proposed Co-H intermediate C and homolytic cleavage of the CoII-H moiety of C, presumably via a dimeric Co intermediate D containing a [Co2(µ-H)2]2+ core, to yield the corresponding 2 and H2.

Plasmon Tuning of Liquid Gallium Nanoparticles through Surface Anodization.

In this work, tunable plasmonic liquid gallium nanoparticles (Ga NPs) were prepared through surface anodizing of the particles. Shape deformation of the Ga NPs accompanied with dimpled surface topographies could be induced during electrochemical anodization, and the formation of the anodic oxide shell helps maintain the resulting change in the particle shape. The nanoscale dimple-like textures led to changes in the localized surface plasmon resonance (LSPR) wavelength. A maximal LSPR red-shift of ~77 nm was preliminarily achieved using an anodization voltage of 0.7 V. The experimental results showed that an increase in the oxide shell thickness yielded a negligible difference in the observed LSPR, and finite-difference time-domain (FDTD) simulations also suggested that the LSPR tunability was primarily determined by the shape of the deformed particles. The extent of particle deformation could be adjusted in a very short period of anodization time (~7 s), which offers an efficient way to tune the LSPR response of Ga NPs.

The sex-specific association of prenatal phthalate exposure with low birth weight and small for gestational age: A nationwide survey by the Taiwan Maternal and Infant Cohort Study (TMICS).

The Taiwan Maternal and Infant Cohort Study (TMICS) was launched with the aim to assess the effects of prenatal exposure to phthalic acid esters (PAEs) on infant health. A total of 1102 pregnant women were enrolled in this study from 2012 to 2015. All participants completed a structured questionnaire, and provided urine specimens. The urinary concentrations of PAE metabolites in the third trimester were measured using liquid chromatography-electrospray ionization tandem mass spectrometry. Generalized additive model-penalized regression splines and logistic regression models were employed to determine the risk for low birth weight (LBW) or small for gestational age (SGA) among pregnant women exposed to PAEs. After adjustments for other covariates, each incremental unit of ln-transformed mono-n-butyl phthalate (MnBP) for pregnant women increased the odds of SGA in male neonates by 1.44 (95% CI: 0.92-2.23). An inverse association between SGA and maternal MnBP exposure level was observed in female neonates. An increase in one ln-transformed MnBP concentration unit decreased the risk of female SGA to 0.50 (95% CI: 0.24-0.97). In the penalized regression splines, increased risks of LBW/SGA in male neonates were presented while pregnant women exposed to increased MnBP levels. However, an association in the opposite direction was observed between maternal MnBP and LBW or SGA for male and female neonates. This study indicated that high maternal MnBP exposure in the third trimester was associated with LBW or SGA for male infants. Adverse effects on susceptible populations exposed to high levels of PAEs should be of concern.

Mixed alkali-ion transport and storage in atomic-disordered honeycomb layered NaKNi2TeO6.

Honeycomb layered oxides constitute an emerging class of materials that show interesting physicochemical and electrochemical properties. However, the development of these materials is still limited. Here, we report the combined use of alkali atoms (Na and K) to produce a mixed-alkali honeycomb layered oxide material, namely, NaKNi2TeO6. Via transmission electron microscopy measurements, we reveal the local atomic structural disorders characterised by aperiodic stacking and incoherency in the alternating arrangement of Na and K atoms. We also investigate the possibility of mixed electrochemical transport and storage of Na+ and K+ ions in NaKNi2TeO6. In particular, we report an average discharge cell voltage of about 4 V and a specific capacity of around 80 mAh g-1 at low specific currents (i.e., < 10 mA g-1) when a NaKNi2TeO6-based positive electrode is combined with a room-temperature NaK liquid alloy negative electrode using an ionic liquid-based electrolyte solution. These results represent a step towards the use of tailored cathode active materials for "dendrite-free" electrochemical energy storage systems exploiting room-temperature liquid alkali metal alloy materials.

Honeycomb layered oxides: structure, energy storage, transport, topology and relevant insights.

The advent of nanotechnology has hurtled the discovery and development of nanostructured materials with stellar chemical and physical functionalities in a bid to address issues in energy, environment, telecommunications and healthcare. In this quest, a class of two-dimensional layered materials consisting of alkali or coinage metal atoms sandwiched between slabs exclusively made of transition metal and chalcogen (or pnictogen) atoms arranged in a honeycomb fashion have emerged as materials exhibiting fascinatingly rich crystal chemistry, high-voltage electrochemistry, fast cation diffusion besides playing host to varied exotic electromagnetic and topological phenomena. Currently, with a niche application in energy storage as high-voltage materials, this class of honeycomb layered oxides serves as ideal pedagogical exemplars of the innumerable capabilities of nanomaterials drawing immense interest in multiple fields ranging from materials science, solid-state chemistry, electrochemistry and condensed matter physics. In this review, we delineate the relevant chemistry and physics of honeycomb layered oxides, and discuss their functionalities for tunable electrochemistry, superfast ionic conduction, electromagnetism and topology. Moreover, we elucidate the unexplored albeit vastly promising crystal chemistry space whilst outlining effective ways to identify regions within this compositional space, particularly where interesting electromagnetic and topological properties could be lurking within the aforementioned alkali and coinage-metal honeycomb layered oxide structures. We conclude by pointing towards possible future research directions, particularly the prospective realisation of Kitaev-Heisenberg-Dzyaloshinskii-Moriya interactions with single crystals and Floquet theory in closely-related honeycomb layered oxide materials.

Inorganic AlCl3-alkali metal thiocyanate ionic liquids as electrolytes for electrochemical Al technologies.

A series of inorganic AlCl3-alkali metal thiocyanate (AMSCN: AM = Li, Na, K) ionic liquids (ILs) are demonstrated as electrolytes for Al electrodeposition and Al-anion rechargeable batteries (AARBs) at 303-363 K. Al deposits with a unique flake nanostructure are obtained in these electrolytes. The assembled AARBs show a stable cyclability over 250 cycles with a reversible capacity of ca. 70 mA h (g-graphite)-1 at 363 K. These inorganic ILs inherit the advantages of conventional chloroaluminate ILs (applicability at near-ambient temperature) and molten salts (cost effectiveness), making them promising electrolyte candidates for industrializable electrochemical Al technologies.

A Zinc-Dual-Halogen Battery with a Molten Hydrate Electrolyte.

Halogen redox couples offer several advantages for energy storage such as low cost, high solubility in water, and high redox potential. However, the operational complexity of storing halogens at the oxidation state via liquid-phase media hampers their widespread application in energy-storage devices. Herein, an aqueous zinc-dual-halogen battery system taking the advantages of redox flow batteries (inherent scalability) and intercalation chemistry (high capacity) is designed and fabricated. To enhance specific energy, the designed cell exploits both bromine and chlorine as the cathode redox couples that are present as halozinc complexes in a newly developed molten hydrate electrolyte, which is distinctive to the conventional zinc-bromine batteries. Benefiting from the reversible uptake of halogens at the graphite cathode, exclusive reliance on earth-abundant elements, and membrane-free and possible flow-through configuration, the proposed battery can potentially realize high-performance massive electric energy storage at a reasonable cost.

High-voltage honeycomb layered oxide positive electrodes for rechargeable sodium batteries.

Honeycomb layered oxides from Na2Ni2-xCoxTeO6 family were assessed for use as positive electrodes in rechargeable sodium batteries at ambient and elevated temperatures using ionic liquids. Substitution of nickel with cobalt increases the discharge voltage to nearly 4 V (versus Na+/Na), surpassing the average voltages of most Na based layered oxide positive electrodes.

Potassium Difluorophosphate as an Electrolyte Additive for Potassium-Ion Batteries.

The limited cyclability and inferior Coulombic efficiency of graphite negative electrodes have been major impediments to their practical utilization in potassium-ion batteries (PIBs). Herein, for the first time, potassium difluorophosphate (KDFP) electrolyte additive is demonstrated as a viable solution to these bottlenecks by facilitating the formation of a stable and K+-conducting solid-electrolyte interphase (SEI) on graphite. The addition of 0.2 wt % KDFP to the electrolyte results in significant improvements in the (de)potassiation kinetics, capacity retention (76.8% after 400 cycles with KDFP vs 27.4% after 100 cycles without KDFP), and average Coulombic efficiency (∼99.9% during 400 cycles) of the graphite electrode. Moreover, the KDFP-containing electrolyte also enables durable cycling of the K/K symmetric cell at higher efficiencies and lower interfacial resistance as opposed to the electrolyte without KDFP. X-ray diffraction and Raman spectroscopy analyses have confirmed the reversible formation of a phase-pure stage-1 potassium-graphite intercalation compound (KC8) with the aid of KDFP. The enhanced electrochemical performance by the KDFP addition is discussed based on the analysis of the SEI layer on graphite and K metal electrodes by X-ray photoelectron spectroscopy.

Potassium Single Cation Ionic Liquid Electrolyte for Potassium-Ion Batteries.

Potassium-ion batteries (PIBs) are a promising post-lithium-ion battery (LIB), as their resources are abundant and low-cost and may have a higher voltage than LIBs. However, the high operating voltage and extremely high reactivity of potassium metal require a chemically safe electrolyte with oxidative and reductive stabilities. In this study, a potassium single cation ionic liquid (K-SCIL), which contains only K+ as the cationic species and has a high electrochemical stability, low flammability, and low vapor pressure, is developed as an electrolyte for PIBs. The mixture of potassium bis(fluorosulfonyl)amide and potassium (fluorosulfonyl)(trifluoromethylsulfonyl)amide at a molar ratio of 55:45 had the lowest melting point of 67 °C. The K+ concentration in this K-SCIL is high (8.5 mol dm-3 at 90 °C) due to the absence of solvents and bulky organic cations. In addition, the electrochemical window is as wide as 5.6 V, which enables the construction of PIBs with a high energy density. A high current density can be achieved with this K-SCIL, owing to the absence of a K+ concentration gradient. The electrolyte was successfully used with a graphite negative electrode, enabling the reversible intercalation/deintercalation of K+, as confirmed by X-ray diffraction.

Fabrication of local micro-contacts to silicon solar cells by dewetting of ultrathin polymer films.

A local contact patterning process based on dewetting of 50 nm-thick polystyrene (PS) films has been developed for fabrication of silicon PERC (Passivated Emitter and Rear Cell) solar cells. Holey PS films with a random pattern of holes were prepared on dielectric passivated silicon wafers through the dewetting process, and then served as etch masks for selective plasma etching of dielectric passivation layers, in doing so metal contact patterns could be generated. The impact of local back contact formation on cell performance was studied as a function of the metallization fraction. This chemical-based patterning process, which broadens the applications of dewetting of polymer films, offers an interesting alternative to laser-based approaches as it may avoid silicon surface damage and lower the manufacturing costs. The application of this patterning technique to PERC fabrication could result in a preliminary efficiency of 13.5% with a V oc = 655 mV and a J sc = 38.4 mA cm-2. An apparent gain in conversion efficiency of 0.6% could be achieved compared to the full-area aluminum back surface field reference cell.

Rechargeable aluminum batteries utilizing a chloroaluminate inorganic ionic liquid electrolyte.

Rechargeable aluminum batteries composed of an aluminum anode, an expanded graphite cathode, and an inorganic chloroaluminate ionic liquid electrolyte show remarkably improved capacity, reversibility, and rate capability at 393 K compared to cells based on a common organic salt based ionic liquid, AlCl3-1-ethyl-3-methylimidazolium chloride.

Evidence of high di(2-ethylhexyl) phthalate (DEHP) exposure due to tainted food intake in Taiwanese pregnant women and the health effects on birth outcomes.

The contamination of a clouding agent with di(2-ethylhexyl) phthalate (DEHP), a substitute emulsifier-containing compound used in a variety of foods was announced on May 23, 2011. The aims of this study were as follows (1) compare the urine phthalates (PAE) metabolites concentration and estimate the daily intake (DI) of PAEs in pregnant women before and after the tainted food scandal and (2) examine the effect of relatively high PAEs exposure on birth outcome. One-hundred twelve pregnant women in Northern Taiwan participated in this study from March to December 2010, i.e., before the tainted food scandal. After the tainted food scandal, we collected 69, 73, and 180 urine specimens (January 2013 to August 2014) from women whom were in their first, second, and third trimesters of pregnancy, respectively. We measure urinary DEHP metabolite concentrations to estimate the DI of DEHP and the hazard quotient (HQ) of subjects. This was the first study to assess the effects of DEHP-tainted food scandal exposure in pregnant women across the three trimesters of pregnancy. After the tainted food report, the concentrations of urine PAE metabolite were significantly decreased, especially those of DEHP metabolites. Based on different reference limit values, the percentages of pregnant women whose HQDEHP value exceeded the limit ranged from 0.53% to 8.93%. Despite this low frequency, the higher ΣPAE exposure during the second trimester may significantly increase the risk of relatively low birth height compared to the lower exposure group (ß=-0.63 (-1.20 to -0.06)). Our results support the hypothesis that exposure to relatively high concentrations of DEHP in pregnant Taiwanese women may have an adverse effect on birth outcomes. The percentage of subjects whose exposure level exceeded the exposure limit was low; however, high PAEs exposure appears to be significantly associated with birth outcomes. Therefore, we suggest that reference dose for PAEs should be revised.

Visualization of Si Anode Reactions in Coin-Type Cells via Operando Scanning Electron Microscopy.

Understanding the electrochemical behavior and controlling the morphological variations of electrodes are critical for the design of high-capacity batteries. In this article, we describe a newly established operando scanning electron microscopy (SEM) to visualize the battery reactions in a modified coin cell, which allowed the simultaneous collection of electrochemical data and time-resolved images. The investigated silicon (Si)-polyimide-binder electrode exhibited a high capacity (∼1500 mAh g-1) and a desirable cyclability. Operando SEM revealed that the morphology of the Si anode drastically changed and cracks formed on the electrode because of the lithiation-induced volume expansion of the Si particles during the first charge process. Interestingly, the thickness variation in the Si composite layer was moderated in subsequent cycles. This strongly suggested that cracking caused by the breakage of the stiff binder alleviated the internal stress experienced by Si. On the basis of this finding by the operando SEM technique, patterned Si electrodes with controlled spacing were successfully fabricated, and their improved performance was confirmed.

In situ Scanning Electron Microscopy of Silicon Anode Reactions in Lithium-Ion Batteries during Charge/Discharge Processes.

A comprehensive understanding of the charge/discharge behaviour of high-capacity anode active materials, e.g., Si and Li, is essential for the design and development of next-generation high-performance Li-based batteries. Here, we demonstrate the in situ scanning electron microscopy (in situ SEM) of Si anodes in a configuration analogous to actual lithium-ion batteries (LIBs) with an ionic liquid (IL) that is expected to be a functional LIB electrolyte in the future. We discovered that variations in the morphology of Si active materials during charge/discharge processes is strongly dependent on their size and shape. Even the diffusion of atomic Li into Si materials can be visualized using a back-scattering electron imaging technique. The electrode reactions were successfully recorded as video clips. This in situ SEM technique can simultaneously provide useful data on, for example, morphological variations and elemental distributions, as well as electrochemical data.

Quantitative analysis of normal fetal medulla oblongata volume and flow by three-dimensional power Doppler ultrasound.

OBJECTIVE: Assessment of the fetal medulla oblongata volume (MOV) and blood flow might be important in the evaluation of fetal brain growth. We used three-dimensional power Doppler ultrasound (3DPDUS) to assess the fetal MOV and blood flow index in normal gestation. The relationships between these parameters were further analyzed. METHODS: We assessed the total volume and blood flow index of the fetal MO in normal pregnancies using a 3DPDUS (Voluson 730 Expert). The true sagittal plane over the fetal occipital area was measured by a 3D transabdominal probe to scan the fetal MO under the power Doppler mode. Then, we quantitatively assessed the total volume of the fetal MOV, mean gray area (MG), vascularization index (VI), and flow index (FI). RESULTS: A total of 106 fetuses, ranging from 19 weeks to 39 weeks of gestation, were involved in our study. The volume of the fetal MO was highly positively correlated with gestational age [correlation coefficient (r) = 0.686, p < 0.0001]. The MG was negatively correlated with gestational age [r = -0.544, p < 0.0001). VI and FI showed no significant correlation with gestational age (p = 0.123 and p = 0.219, respectively). CONCLUSION: 3DPDUS can be used to assess the fetal MOV and blood flow development quantitatively. Our study indicated that fetal MOV and blood flow correlated significantly with the advancement of gestational age. This information may serve as reference data for further studies of the fetal brain and blood flow under abnormal conditions.

Vaginal birth after cesarean section: 10 years of experience in a tertiary medical center in Taiwan.

OBJECTIVE: Because of the increased risk of uterine rupture and other morbidities, instances of trial of labor after cesarean (TOLAC) have decreased in number each year. Nevertheless, under careful assessment and advanced medical care, TOLAC is still a safe option for delivery. The objective of this study is to find the factors that impact the success rate for TOLAC and to compare the results with Taiwan national registry data. MATERIALS AND METHODS: A longitudinal cohort study that includes a total of 254 cases of women receiving TOLAC in a tertiary medical center over a period of 10 years. RESULTS: A total of 254 participants who underwent TOLAC, which accounts for 1.67% of total labor instances (254/15,166), were enrolled for analysis. The success rate of TOLAC was found to be 80.70% (205/254), including 146 (57.5%) normal deliveries, 45 (17.7%) vacuum-assisted deliveries, and 14 (5.5%) forceps-assisted deliveries. The conversion rate to cesarean section was 19.3%. There were no uterine rupture cases in our study, and there were only two suspected cases, which turned out to have no actual rupture. When analyzing the factors affecting the results of TOLAC, we found that a successfully spontaneously delivered baby had a lower birth weight than the failed TOLAC cases that were converted to cesarean delivery (mean, 2989 g vs. 3379 g; p < 0.001). Among the patients who were converted to cesarean section, the most common reason was dysfunctional labor (79.6%), followed by fetal distress (14.3%). CONCLUSION: Under intensive care and observation, TOLAC section may still be a feasible choice. Nevertheless, the body weight of the baby has been shown to be a factor that can influence the success rate.