Amine-modified polyionic liquid supports enhance the efficacy of PdNPs for the catalytic hydrogenation of CO2 to formate

Palladium nanoparticles stabilised by aniline modified polymer immobilised ionic liquid is a remarkably active catalyst for the hydrogenation of CO2 to formate; the initial TOF of 500 h-1 is markedly higher than either unmodified catalyst or its benzylamine and N,N-dimethylaniline modified counterparts and is among the highest to be reported for a PdNP-based catalyst.

High Current Cycling in a Superconcentrated Ionic Liquid Electrolyte to Promote Uniform Li Morphology and a Uniform LiF-Rich Solid Electrolyte Interphase

High-energy-density systems with fast charging rates and suppressed dendrite growth are critical for the implementation of efficient and safe next-generation advanced battery technologies such as those based on Li metal. However, there are few studies that investigate reliable cycling of Li metal electrodes under high-rate conditions. Here, by employing a superconcentrated ionic liquid (IL) electrolyte, we highlight the effect of Li salt concentration and applied current density on the resulting Li deposit morphology and solid electrolyte interphase (SEI) characteristics, demonstrating exceptional deposition/dissolution rates and efficiency in these systems. Operation at higher current densities enhanced the cycling efficiency, e.g., from 64 ± 3% at 1 mA cm^-2 up to 96 ± 1% at 20 mA cm^-2 (overpotential <±0.2 V), while resulting in lower electrode resistance and dendrite-free Li morphology. A maximum current density of 50 mA cm^-2 resulted in 88 ± 3% cycling efficiency, displaying tolerance for high overpotentials at the Ni working electrode (0.5 V). X-ray photoelectron microscopy (XPS), time-of-flight secondary-ion mass spectroscopy (ToF-SIMS), and scanning electron microscopy (SEM) surface measurements revealed that the formation of a stable SEI, rich in LiF and deficient in organic carbon species, coupled with nondendritic and compact Li morphologies enabled enhanced cycling efficiency at higher currents. Reduced dendrite formation at high current is further highlighted by the use of a highly porous separator in coin cell cycling (1 mAh cm^-2 at 50 °C), sustaining 500 cycles at 10 mA cm^-2.

Surface SiO2 Thickness Controls Uniform-to-Localized Transition in Lithiation of Silicon Anodes for Lithium-Ion Batteries

Silicon is a promising anode material for lithium-ion batteries because of its high capacity, but its widespread adoption has been hampered by a low cycle life arising from mechanical failure and the absence of a stable solid-electrolyte interphase (SEI). Understanding SEI formation and its impact on cycle life is made more complex by the oxidation of silicon materials in air or during synthesis, which leads to SiO_x coatings of varying thicknesses that form the true surface of the electrode. In this paper, the lithiation of SiO₂-coated Si is studied in a controlled manner using SiO₂ coatings of different thicknesses grown on Si wafers via thermal oxidation. SiO₂ thickness has a profound effect on lithiation: below 2 nm, SEI formation followed by uniform lithiation occurs at positive voltages versus Li/Li⁺. Si lithiation is reversible, and SiO₂ lithiation is largely irreversible. Above 2 nm SiO₂, voltammetric currents decrease exponentially with SiO₂ thickness. For 2-3 nm SiO₂, SEI formation above 0.1 V is suppressed, but a hold at low or negative voltages can initiate charge transfer whereupon SEI formation and uniform lithiation occur. Cycling of Si anodes with an SiO₂ coating thinner than 3 nm occurs at high Coulombic efficiency (CE). If an SiO₂ coating is thicker than 3-4 nm, the behavior is totally different: lithiation at positive voltages is strongly inhibited, and lithiation occurs at poor CE and is highly localized at pinholes which grow over time. As they grow, lithiation becomes more facile and the CE increases. Pinhole growth is proposed to occur via rapid transport of Li along the SiO₂/Si interface radially outward from an existing pinhole, followed by the lithiation of SiO₂ from the interface outward.

Nonpassivated Silicon Anode Surface

A stable solid electrolyte interphase (SEI) has been proven to be a key enabler to most advanced battery chemistries, where the reactivity between the electrolyte and the anode operating beyond the electrolyte stability limits must be kinetically suppressed by such SEIs. The graphite anode used in state-of-the-art Li-ion batteries presents the most representative SEI example. Because of similar operation potentials between graphite and silicon (Si), a similar passivation mechanism has been thought to apply on the Si anode when using the same carbonate-based electrolytes. In this work, we found that the chemical formation process of a proto-SEI on Si is closely entangled with incessant SEI decomposition, detachment, and reparation, which lead to continuous lithium consumption. Using a special galvanostatic protocol designed to observe the SEI formation prior to Si lithiation, we were able to deconvolute the electrochemical formation of such dynamic SEI from the morphology and mechanical complexities of Si and showed that a pristine Si anode could not be fully passivated in carbonate-based electrolytes.

A map of the inorganic ternary metal nitrides

Exploratory synthesis in new chemical spaces is the essence of solid-state chemistry. However, uncharted chemical spaces can be difficult to navigate, especially when materials synthesis is challenging. Nitrides represent one such space, where stringent synthesis constraints have limited the exploration of this important class of functional materials. Here, we employ a suite of computational materials discovery and informatics tools to construct a large stability map of the inorganic ternary metal nitrides. Our map clusters the ternary nitrides into chemical families with distinct stability and metastability, and highlights hundreds of promising new ternary nitride spaces for experimental investigation-from which we experimentally realized seven new Zn- and Mg-based ternary nitrides. By extracting the mixed metallicity, ionicity and covalency of solid-state bonding from the density functional theory (DFT)-computed electron density, we reveal the complex interplay between chemistry, composition and electronic structure in governing large-scale stability trends in ternary nitride materials.

High Efficiency Si Photocathode Protected by Multifunctional GaN Nanostructures

Photoelectrochemical water splitting is a clean and environmentally friendly method for solar hydrogen generation. Its practical application, however, has been limited by the poor stability of semiconductor photoelectrodes. In this work, we demonstrate the use of GaN nanostructures as a multifunctional protection layer for an otherwise unstable, low-performance photocathode. The direct integration of GaN nanostructures on n⁺-p Si wafer not only protects Si surface from corrosion but also significantly reduces the charge carrier transfer resistance at the semiconductor/liquid junction, leading to long-term stability (>100 h) at a large current density (>35 mA/cm²) under 1 sun illumination. The measured applied bias photon-to-current efficiency of 10.5% is among the highest values ever reported for a Si photocathode. Given that both Si and GaN are already widely produced in industry, our studies offer a viable path for achieving high-efficiency and highly stable semiconductor photoelectrodes for solar water splitting with proven manufacturability and scalability.

Redox-Mediated Stabilization in Zinc Molybdenum Nitrides

We report on the theoretical prediction and experimental realization of new ternary zinc molybdenum nitride compounds. We used theory to identify previously unknown ternary compounds in the Zn-Mo-N systems, Zn₃MoN₄ and ZnMoN₂, and to analyze their bonding environment. Experiments show that Zn-Mo-N alloys can form in broad composition range from Zn₃MoN₄ to ZnMoN₂ in the wurtzite-derived structure, accommodating very large off-stoichiometry. Interestingly, the measured wurtzite-derived structure of the alloys is metastable for the ZnMoN₂ stoichiometry, in contrast to the Zn₃MoN₄ stoichiometry, where ordered wurtzite is predicted to be the ground state. The formation of Zn₃MoN₄-ZnMoN₂ alloy with wurtzite-derived crystal structure is enabled by the concomitant ability of Mo to change oxidation state from +VI in Zn₃MoN₄ to +IV in ZnMoN₂, and the capability of Zn to contribute to the bonding states of both compounds, an effect that we define as "redox-mediated stabilization". The stabilization of Mo in both the +VI and +IV oxidation states is due to the intermediate electronegativity of Zn, which enables significant polar covalent bonding in both Zn₃MoN₄ and ZnMoN₂ compounds. The smooth change in the Mo oxidation state between Zn₃MoN₄ and ZnMoN₂ stoichiometries leads to a continuous change in optoelectronic properties-from resistive and semitransparent Zn₃MoN₄ to conductive and absorptive ZnMoN₂. The reported redox-mediated stabilization in zinc molybdenum nitrides suggests there might be many undiscovered ternary compounds with one metal having an intermediate electronegativity, enabling significant covalent bonding, and another metal capable of accommodating multiple oxidation states, enabling stoichiometric flexibility.

Band alignment at the interface between Ni-doped Cr2O3 and Al-doped ZnO: implications for transparent p-n junctions

The realization of transparent electronic and optoelectronic devices requires the use of transparent p-n junctions. In this context, understanding the band alignment at the interface between the p- and n-components represents a fundamental step towards the realization of high performance devices. In this work, the band alignment at the interface between Al-doped ZnO (AZO) and Ni-doped Cr2O3 has been analysed. The formation and evolution of the core levels as the interface progressively forms have been followed by means of x-ray Photoelectron Spectroscopy, x-ray diffraction and x-ray reflectivity. A type two (staggered) band alignment was identified, with the valence band offset and conduction band offset found to be 2.6 eV and 2.5 eV, respectively. The electrical behaviour will be discussed in terms of the position of the bands, the presence of band bending and the expected built-in potential and how these can be engineered in order to achieve the maximum performance for this hetero-structure.

Assessing the potential of Mg-doped Cr₂O₃ as a novel p-type transparent conducting oxide

One of the current challenges faced by material scientists is the development of a p-type transparent conducting oxide with levels of optical transparency and electronic conductivity to equal those of the universally n-type industry leaders such as Sn-doped In2O3. The discovery of a p-type analogue would allow for the combination of both polarities into a heterojunction, accessing the potential for transparent electronics. In this study, an insulating material, Cr2O3, is investigated both experimentally and computationally to determine if it is a viable p-type host matrix as has been recently proposed in the literature. The geometric and electronic structure are examined by high resolution x-ray diffraction, x-ray photoelectron spectroscopy, and periodic density functional theory (specifically, PBE  +  U). By incorporating Mg and performing a comprehensive defect analysis, the dominant intrinsic and extrinsic carriers in the material are determined, and it is shown that Cr2O3 has the potential to display p-type conductivity when appropriately doped.

Follicular mucinosis responding to isotretinoin treatment

Follicular mucinosis is a rare disorder of unknown etiology characterized by accumulation of mucin in the sebaceous glands and outer root sheaths of the hair follicles. It is divided into a primary benign type and a secondary type mostly associated with lymphomas. No effective standard therapy for follicular mucinosis is available. We describe the case of a 21-year-old Caucasian male who had papules, nodules, and erythematous plaques on his left shoulder, left arm, and right scapular region. He was diagnosed as primary benign generalized follicular mucinosis, and treated with isotretinoin. Almost complete remission was achieved in 4 months.

Growth of Ag nanometre-sized particles in solution: molecular dynamics simulations

This work focuses on the growth of nanometre-sized Ag clusters in solution. Molecular dynamics simulations have been employed to gain the necessary detail on the dynamics of solute species and to study the mechanistic features of the processes governing the association of solute atoms in aggregates. Supersaturated liquid solutions of Ag in tetrachloromethane have been considered. A systematic variation of the concentration of Ag atoms in solution permitted us to show the different mechanistic scenarios responsible for the growth processes of solid Ag clusters. It is shown that such processes are limited by the thermal diffusion of solute in the solution bulk at relatively low supersaturation degrees, whereas the growth is limited by interfacial effects at relatively high supersaturation degrees.

Polymerase chain reaction based detection of Mycobacterium tuberculosis complex in lupus vulgaris: a case report

Lupus vulgaris (LV), the commonest of all forms of cutaneous tuberculosis, can affect the earlobes. Authors present a 20-year-old male patient with LV of the left earlobe initially misdiagnosed as pyoderma and treated superfluously with antibiotics at different intervals over the last 4 years in another hospital. Mycobacteria could not be seen or isolated by stained smears or conventional or radiometric culture methods from the skin biopsy specimens. Suspected clinical diagnosis of our patient was LV. This was supported by positive polymerase chain reaction assay and histological findings. The lesion was treated successfully with anti-tuberculosis chemotherapy, further confirming the diagnosis of LV.

Efficacy and safety assessment of 0.5% and 1% colchicine cream in the treatment of actinic keratoses

BACKGROUND

Topical colchicine has been reported to be an effective treatment for actinic keratoses, but the optimal concentration has not been fully defined.

OBJECTIVE

The aim of this study was to further support the beneficial effect of topical colchicine therapy for actinic keratoses, and to compare the efficacy and safety of two different concentrations of colchicine cream, 0.5% and 1%.

METHODS

Sixteen patients with actinic keratoses were enrolled in this comparative randomized study. Eight patients applied 1% colchicine cream, twice daily on their lesions while the other eight were treated with a 0.5% colchicine cream for 10 days. Some patients were applied a second course of 10 days' therapy. Patients were examined before treatment and at 10 days, and followed up at 1, 2 and 6 months of treatment. Visible and palpable actinic keratoses lesions in each group were counted. Safety and efficacy were also assessed by clinical examination at each study visit. Routine laboratory tests were performed before and after treatment.

RESULTS

Actinic keratoses lesions showed significant clinical improvement following treatment with 0.5% and 1% colchicine cream. Complete healing of actinic keratoses were observed in six of the eight patients in the 1% colchicine group, and in seven of the eight patients in the 0.5% colchicine group. The reduction rate in number of actinic keratoses at the end of treatment in the 1% colchicine group was 73.9% (48/65) (p < 0.001), and the reduction rate in the 0.5% colchicine group was 77.7% (52/67) in total (p < 0.001). The reduction in number of actinic keratoses (mean +/- SD) at the end of treatment was similar in the 1% colchicine group (0.7 +/- 1.3), and the 0.5% colchicine group (mean 0.6 +/- 1.7) (p > 0.05). Systemic side effects were not seen in either concentration.

CONCLUSIONS

Topical colchicine is an effective and safe alternative agent. Cream containing 0.5% of colchicine is equally effective as 1% colchicine cream in the treatment of actinic keratoses.

An open, randomized, comparative study of oral fluconazole, itraconazole and terbinafine therapy in onychomycosis

BACKGROUND/AIM

In this open, randomized and comparative study, the safety and efficacy of systemic fluconazole, itraconazole and terbinafine was investigated in 50 patients with distal subungual toenail onychomycosis diagnosed clinically and mycologically. The patients with positive mycology and also the patients with positive microscopy and negative culture were investigated.

METHODS

The treatment duration was 3 months, and the follow-up period was 6 months. Patients were randomly assigned: 16 patients received 150 mg fluconazole once weekly, 18 patients received 200 mg itraconazole twice daily with meals during the first week of each month, and 16 patients received 250 mg/day terbinafine during the treatment period.

RESULTS

In a clinical evaluation, at the endpoint of the follow-up period, the clinical cure rates were 81.3% (13/16) in the terbinafine group, 77.8% (14/18) in the itraconazole group, and 37.5% (6/16) in the fluconazole group. The mycological cure rates were 75% (12/16), 61.1% (11/18) and 31.2% (5/16), respectively. The overall assessment rates were 62.5% (10/16), 61.1% (11/18) and 31.2% (5/16), respectively. Statistically significant intra-group reductions from baseline symptom severity values were seen at the endpoint of treatment and at the endpoint of the follow-up period for all three treatment groups in onycholysis, subungual hyperkeratosis, affected-area percentage score and total score parameters (p < 0.001). At the endpoint of the follow-up period, statistically significant differences between the treatment groups were seen in clinical, mycological and overall assessment (p < 0.05). However, while no statistically significant difference between the terbinafine and itraconazole groups was seen, there was a clinical and statistical difference between the other groups and the fluconazole group. Treatment was not stopped for side effects such as mild gastrointestinal and central nervous system symptoms. These effects were noted in four patients in the fluconazole group (25%), five patients in the itraconazole group (27.8%), and three patients in the terbinafine group (18.75%). The clinical laboratory data on all three drug groups did not show any statistically or clinically significant intra-group changes from baseline values at the endpoint (p > 0.05).

CONCLUSION

This comparative study of systemic fluconazole, itraconazole and terbinafine showed that all three drugs were effective and safe in the treatment of onychomycosis. However, fluconazole, at these doses and treatment durations, was the least effective. With regard to cost-effectiveness, side effects and the cure rates, terbinafine could be the drug of choice in the short-term treatment of toenail onychomycosis.

Preparation of polyethyleneglycol (PEG) coatings for microencapsulation of charcoal

Polyethyleneglycols (PEGs) with their high solubility in water cannot normally be used as a coating material in aqueous solutions such as blood. A gamma-radiation procedure was therefore applied after coating charcoal granules with PEG in a non-aqueous phase, and an 80-90% insoluble polymer matrix on charcoal was obtained. PEGs with different molecular weights from 4000 to 300,000 were used for coating. The performance of this system was determined by using several test solutes, namely creatinine, uric acid, and vitamin B-12. It was observed that the pore size and structure of these membranes can be adjusted by changing the irradiation time and by using PEGs with different molecular weights. Thus, very high mass transfer rates can be achieved.