Unlocking Li superionic conductivity in face-centred cubic oxides via face-sharing configurations.

Oxides with a face-centred cubic (fcc) anion sublattice are generally not considered as solid-state electrolytes as the structural framework is thought to be unfavourable for lithium (Li) superionic conduction. Here we demonstrate Li superionic conductivity in fcc-type oxides in which face-sharing Li configurations have been created through cation over-stoichiometry in rocksalt-type lattices via excess Li. We find that the face-sharing Li configurations create a novel spinel with unconventional stoichiometry and raise the energy of Li, thereby promoting fast Li-ion conduction. The over-stoichiometric Li-In-Sn-O compound exhibits a total Li superionic conductivity of 3.38 × 10-4 S cm-1 at room temperature with a low migration barrier of 255 meV. Our work unlocks the potential of designing Li superionic conductors in a prototypical structural framework with vast chemical flexibility, providing fertile ground for discovering new solid-state electrolytes.

Correlation of Conductive Hearing Impairment With Sizes of Adenoids in the Pediatric Age Group: An Observational Case-Control Study.

INTRODUCTION: When adenoids enlarge and elicit symptoms it is referred to as symptomatic adenoids, which is a preventable cause of hearing loss and nasal obstruction in the pediatric age group. This study was done to correlate conductive hearing loss with the size of adenoids and to emphasize the importance of screening in the pediatric age group. METHODS: An observational case-control study was conducted to analyze the degree of hearing impairment in children with adenoid hypertrophy. In total, 98 patients with at least one symptom of adenoid hypertrophy aged between 5 and <15 years were recruited. Those with conductive hearing loss were in the case group and those with normal hearing were in the control group. Audiometry, tympanogram, X-ray, and fibreoptic nasal endoscopy were conducted and compared. RESULTS: The mean age of presentation of conductive hearing loss with adenoids was 7.67 years. The mean conductive hearing loss on audiometry was 31.69 dB. Tympanogram showed a type B curve in 40.81% of ears and type C in 26.53%. On X-ray nasopharynx, the majority of cases had grade III hypertrophy followed by grade II and grade IV. In nasal endoscopy, most cases had second-degree adenoid hypertrophy followed by third degree, first degree, and then fourth degree. The highest degree of hearing loss of 32-48 dB was present with fourth-degree adenoids. Conductive hearing loss was five times more in patients with third- and fourth-degree adenoids. CONCLUSIONS: In our study, adenoid hypertrophy has a positive correlation with conductive hearing loss in pediatric patients. So proper screening and early management should be done to prevent hearing loss in children.

Enhanced Electrochemical Performance of Disordered Rocksalt Cathodes Enabled by a Graphite Conductive Additive.

Cobalt-free cation-disordered rocksalt (DRX) cathodes are a promising class of materials for next-generation Li-ion batteries. Although they have high theoretical specific capacities (>300 mA h/g) and moderate operating voltages (∼3.5 V vs Li/Li+), DRX cathodes typically require a high carbon content (up to 30 wt %) to fully utilize the active material which has a detrimental impact on cell-level energy density. To assess pathways to reduce the electrode's carbon content, the present study investigates how the carbon's microstructure and loading (10-20 wt %) influence the performance of DRX cathodes with the nominal composition Li1.2Mn0.5Ti0.3O1.9F0.1. While electrodes prepared with conventional disordered carbon additives (C65 and ketjenblack) exhibit rapid capacity fade due to an unstable cathode/electrolyte interface, DRX cathodes containing 10 wt % graphite show superior cycling performance (e.g., reversible capacities ∼260 mA h/g with 85% capacity retention after 50 cycles) and rate capability (∼135 mA h/g at 1000 mA/g). A suite of characterization tools was employed to evaluate the performance differences among these composite electrodes. Overall, these results indicate that the superior performance of the graphite-based cathodes is largely attributed to the: (i) formation of a uniform graphitic coating on DRX particles which protects the surface from parasitic reactions at high states of charge and (ii) homogeneous dispersion of the active material and carbon throughout the composite cathode which provides a robust electronically conductive network that can withstand repeated charge-discharge cycles. Overall, this study provides key scientific insights on how the carbon microstructure and electrode processing influence the performance of DRX cathodes. Based on these results, exploration of alternative routes to apply graphitic coatings is recommended to further optimize the material performance.

Novel Focused Ion Beam Liftouts for Spatial Characterization of Spherical Biominerals With Transmission Electron Microscopy.

Focused ion beam (FIB) is frequently used to prepare electron- and X-ray-beam-transparent thin sections of samples, called lamellae. Typically, lamellae are prepared from only a subregion of a sample. In this paper, we present a novel approach for FIB lamella preparation of microscopic samples, wherein the entire cross-section of the whole sample can be investigated. The approach was demonstrated using spherical, porous, and often hollow microprecipitates of biologically precipitated calcium carbonate. The microprecipitate morphology made these biogenic samples more fragile and challenging than materials commonly investigated using FIB lamellae. Our method enables the appropriate orientation of the lamellae required for further electron/X-ray analyses after attachment to the transmission electron microscopy (TEM) grid post and facilitates more secure adhesion onto the grid post. We present evidence of autofluorescence in bacterially precipitated vaterite using this lamella preparation method coupled with TEM selected area diffraction. This innovative approach allows studying biomineralization at the micro to nano scales, which can provide novel insights into bacterial responses to microenvironmental conditions.

Enhancing the Electrode Gravimetric Capacity of Li1.2Mn0.4Ti0.4O2 Cathode Using Interfacial Carbon Deposition and Carbon Nanotube-Mediated Electrical Percolation.

Mn-based cation-disordered rocksalt oxides (Mn-DRX) are emerging as promising cathode materials for next-generation Li-ion batteries due to their high specific capacities and cobalt- and nickel-free characteristic. However, to reach the usable capacity, solid-state synthesized Mn-DRX materials require activation via postsynthetic ball milling, typically incorporating more than 20 wt % conductive carbon that adversely reduces the electrode-level gravimetric capacity. To address this issue, we first deposit amorphous carbon on the surface of the Li1.2Mn0.4Ti0.4O2 (LMTO) particles to increase the electrical conductivity by 5 orders of magnitude. Although the cathode material gravimetric first charge capacity reaches 180 mAh/g, its highly irreversible behavior leads to a first discharge capacity of 70 mAh/g. Subsequently, to ensure a good electrical percolation network, the LMTO material is ball-milled with a multiwall carbon nanotube (CNT) to obtain a 78.7 wt % LMTO active material loading in the cathode electrode (LMTO-CNT). As a result, a 210 mAh/g cathode electrode gravimetric first charge and 165 mAh/g first discharge capacity values are obtained, compared to the respective capacity values of 222 and 155 mAh/g for the LMTO material ball-milled with 20 wt % SuperP C65 electrode (LMTO-SP). After 50 cycles, LMTO-CNT delivers a 121 mAh/g electrode gravimetric discharge capacity, largely outperforming the value of 44 mAh/g of LMTO-SP. Our study demonstrates that while ball milling is necessary to achieve a significant amount of capacity of LMTO, a careful selection of additives, such as CNT, effectively reduces the required carbon quantity to achieve a higher electrode gravimetric discharge capacity.

Stacking Faults Assist Lithium-Ion Conduction in a Halide-Based Superionic Conductor.

In the pursuit of urgently needed, energy dense solid-state batteries for electric vehicle and portable electronics applications, halide solid electrolytes offer a promising path forward with exceptional compatibility against high-voltage oxide electrodes, tunable ionic conductivities, and facile processing. For this family of compounds, synthesis protocols strongly affect cation site disorder and modulate Li+ mobility. In this work, we reveal the presence of a high concentration of stacking faults in the superionic conductor Li3YCl6 and demonstrate a method of controlling its Li+ conductivity by tuning the defect concentration with synthesis and heat treatments at select temperatures. Leveraging complementary insights from variable temperature synchrotron X-ray diffraction, neutron diffraction, cryogenic transmission electron microscopy, solid-state nuclear magnetic resonance, density functional theory, and electrochemical impedance spectroscopy, we identify the nature of planar defects and the role of nonstoichiometry in lowering Li+ migration barriers and increasing Li site connectivity in mechanochemically synthesized Li3YCl6. We harness paramagnetic relaxation enhancement to enable 89Y solid-state NMR and directly contrast the Y cation site disorder resulting from different preparation methods, demonstrating a potent tool for other researchers studying Y-containing compositions. With heat treatments at temperatures as low as 333 K (60 °C), we decrease the concentration of planar defects, demonstrating a simple method for tuning the Li+ conductivity. Findings from this work are expected to be generalizable to other halide solid electrolyte candidates and provide an improved understanding of defect-enabled Li+ conduction in this class of Li-ion conductors.

Surgical Procedure among Patients with Foreign Body Obstruction in Food Passage in a Tertiary Care Hospital: A Descriptive Cross-sectional Study.

INTRODUCTION: Foreign body is any object in a region it is not meant to be, where it can cause harm if immediate medical attention is not sought. Its removal by surgical procedure is one of the commonest surgeries done. The objective is to find out prevalence of the patients who underwent operation for foreign bodies obstruction in food passage in the Department of Otorhinolaryngology-Head and Neck Surgery in a tertiary care centre. METHODS: A descriptive cross-sectional study conducted among patients operated in the Department of Otorhinolaryngology and Head and Neck Surgery of a tertiary care center from August 2014 to May 2017. Ethical approval was received from the Institutional Review Committee of the Institute. Convenience sampling method was used. Statistical Package for the Social Sciences was used for analysis. Point estimate at 95% Confidence Interval was calculated along with frequency and proportion for binary data. RESULTS: Out of total 700 patients having operation in department, 115 (16.42%) (95% Confidence Interval = 13.67-19.16) had operation for foreign body obstruction in the food passage. Among 115 patients, 62 (53.90%) were males and 53 (46.10%) were females. Most common foreign bodies ingested in children was coin 17 (14.78%) and bone chips 40 (34.78%) in adults. Cricopharynx 90 (78.26%) is the commonest site for foreign body lodgement. CONCLUSIONS: Prevalence of the patients who underwent operation for foreign bodies obstruction in food passage in a tertiary care hospital is high. Their removal by rigid oesophagoscopy is one of the commonest surgical procedures done in tertiary care center.

Histopathology of Sinonasal and Nasopharyngeal Neoplastic Lesions in a Tertiary Care Center of Western Nepal: A Descriptive Cross-sectional Study.

INTRODUCTION: Sinonasal and nasopharyngeal regions harbor diverse clinical conditions including many non-neoplastic and neoplastic lesions presenting with nasal obstruction, facial pain and swelling, rhinorrhea, epistaxis, and other oral, ear, and orbital symptoms. Histopathology of excised lesions is the mainstay for the definitive diagnosis and management of neoplastic lesions. The aim of this study is to find out the prevalence of neoplastic lesions among sinonasal and nasopharyngeal masses. METHODS: This was a descriptive cross-sectional study conducted among sinonasal and nasopharyngeal masses in the Department of Pathology of a tertiary care center of western Nepal with primary data of 20 years from January 2001 to May 2020. Ethical approval was taken from the Institutional Review Committee. Convenience sampling method was used. Data management and statistical analysis were done using Statistical Package for Social Sciences. Point estimate at 95% Confidence Interval was calculated along with frequency and percentage. RESULTS: Out of 395 sinonasal and nasopharyngeal lesions, 134 (33.92%) (29.26-38.58 at 95% Confidence Interval) were neoplastic lesions. The malignant lesions were found to be 60 (44.77%). Inverted papilloma was the most common benign lesion comprising 28 (20.89%) of cases, and squamous cell carcinoma and nasopharyngeal carcinoma were the most common malignant lesions comprising 12 (8.95%) cases each. CONCLUSIONS: This study observed a variety of neoplastic lesions. The most common benign lesion was nasal polyp and squamous cell carcinoma and nasopharyngeal carcinoma were the most common malignant lesions.

Nanosecond switchable localized surface plasmons through resettable contact angle behavior in silver nanoparticles.

In this article, we show nanosecond switchable localized surface plasmon resonance (LSPR) dipole and quadrupole modes from silver (Ag) nanoparticles on fused quartz substrates. Near-spherical Ag nanoparticles (contact angle of 166°± 9 ) were synthesized by Ultra Violet (UV) laser dewetting of Ag thin films under a glycerol fluid environment. Under a single 9 nanosecond laser pulse irradiation of the particles in air, the particles were changed into a near-hemispherical shape (with contact angle of 103°± 7 ). The resulting changes in particle contact area and volume fraction in the dielectric media resulted in substantial shift in the wavelength and intensity of the dipolar and quadrupolar LSPR modes to the violet side of visible spectrum. This switching of the plasmon resonance wavelength position could be repeated over multiple cycles by resetting the contact angle by laser re-irradiation under glycerol. This reusable nanoparticle system with reversible plasmonic properties within nanosecond time scales could prove a cost-effective way of designing high speed plasmonic devices in desired wavelength regions.

In Situ Contact Angle Tuning of Silver Nanostructures by Laser Heating in Different Fluid Ambient.

It has been theoretically suggested by Yan et al. (Colloids Surf., A 2013, 429, 142-148) that the contact angle θc of a liquid droplet on any given surface can be controlled by immersing it in an appropriate surrounding environment. Here, we report the first experimental demonstration of such an in situ contact angle tuning of silver (Ag) nanoparticles on quartz substrates via nanosecond pulsed laser heating under various fluid ambients, like air, water, and glycerol. Nanosphere lithography (NSL) was used to deposit Ag nanopyramids on quartz substrates. This system was subsequently melted by laser heating inside the various fluids to form nanoparticles. By using a combination of top and side view scanning electron microscopy (SEM) imaging, we show that the contact angle of Ag nanoparticles could be increased by going from heating in air to heating under fluids, with a near hemispherical shape (θc ∼ 99°) under air irradiation to nearly spherical (θc ∼ 167°) under glycerol irradiation. The mechanism of this contact angle change could be explained qualitatively by the changing interfacial energies of the substrate and metal in the various fluids. Similar contact angle control was also achieved for nanoparticles created by dewetting of Ag thin films in the various fluids. One practical implication of this contact angle tunability is the ability to change the intensity ratio of the quadrupolar to dipolar localized surface plasmon resonances in the Ag nanoparticles. This work also has implications to those applications in which nanoparticles on a substrate are heated in various gas or fluid ambients, such as in catalysis, as the ensuing shape change can modify properties.

Thermal and Plasmonic Stabilization of Silver Nanostructures Using a Bilayer Anchoring Technique.

In this work, we demonstrate how to suppress the shape instability of silver (Ag) nanotriangular pyramids following high-temperature annealing without a coating or encapsulation, thus producing a more stable optical plasmonic system. Nanosphere lithography (NSL) was used to fabricate large-area arrays of nanotriangular pyramids of Ag on glass substrates. By using a combination of morphology and spectroscopic studies it was found that exposure of this system to high temperatures of 473 K and beyond in air led to a rapid change in nanostructure shape, and thus, the surface area, with a substantial change to the original plasmonic character. On the other hand, NSL nanotriangular pyramids made from bilayers of Ag on Co or Co on Ag showed much smaller changes in shape and area following annealing up to 573 K in air. In the case of pure Ag, the NSL nanotriangular pyramid changed into a more spherical shape with an overall decrease of ∼24% in its surface area following annealing at 573 K. This lead to a large blue shift of over ∼287 nm or ∼39% in the location of the dipolar plasmonic resonance. On the other hand, the triangular shape of Ag was retained in both the metal bilayer cases, with much smaller area changes of ∼10 and ∼9%, for the Ag deposit when on Co and when under Co, respectively. Consequently, the plasmonic shifts were substantially smaller, of ∼65 nm or about 9%, in these bilayer systems. The mechanism for this stabilization was attributed to the higher surface energy of Co and much lower diffusivity of Co as well as Ag on Co that resulted in an anchoring of the Ag shape to its original state. The plasmonic quality factor for the bimetal NSL nanotriangular pyramids also showed substantially improved stability over pure Ag, further indicating that this anchoring approach is a viable pathway to produce pristine Ag surfaces for high-temperature plasmonic applications.

Treatment of Acute Painful Thyroiditis with Low Dose Prednisolone: A Study on Patients from Western Nepal.

INTRODUCTION: Thyroiditis is a disorder that involves inflammation of the thyroid gland. Subacute thyroiditis is the most common cause of acute painful thyroiditis. It is thought to be a viral inflammatory disorder. Subacute thyroiditis has been treated with either nonsteroidal anti-inflammatory drugs (NSAIDs) or high dose corticosteroids. The response to steroids is more dramatic and quicker than the NSAIDs. Prednisolone is the most commonly used corticosteroid to treat subacute thyroiditis. The usual dose is one mg/kg/day tapered over six weeks although the basis for this dose has not been established yet by prospective studies. AIM: The current research was carried out to study if prednisolone in lower initial dose (20 mg/day tapered over four weeks) is effective in patients with acute painful thyroiditis. MATERIALS AND METHODS: This study was a prospective, cross sectional, observational study carried out at Pokhara, Nepal. All the patients presenting with anterior neck pain of less than 1 week with tender thyroid on palpation and ESR more than 30mm/h were included in the study. The patients were administered prednisolone in a starting dose of 20 mg/day tapered over four weeks. Data were collected, analysed and the results were interpreted. RESULTS: One hundred and twenty two patients of acute painful thyroiditis were included in our study. Age of the patients ranged from 19 years to 69 years with the mean age of 36.58 years. Female to Male ratio was 10:1. Mean ESR was 57.03 at the time of presentation. ESR decreased to 29.63 at two weeks and 17.03 mm per hour (normal) at 4 weeks after continuation of the drug. All the patients reported with severe pain in the anterior neck at the time of presentation. Pain was completely relieved in 115 patients (94%) at 2 weeks after starting the treatment and it was better than previous in seven patients. CONCLUSION: Twenty mg of prednisolone daily tapered over 4 weeks is an adequate treatment of subacute thyroiditis. However, dose can be drastically tapered after 2 weeks.

Epidemiological Study of Laryngeal Carcinoma in Western Nepal.

BACKGROUND: Laryngeal malignancy is a common malignancy of the head and neck region. Affected patients usually present with features that are characteristic of certain subsites. The larynx is oncologically divided into three: supraglottis, glottis and subglottis. Studies from Western countries have shown that the glottis is the commonest subsite to harbour laryngeal malignancy. However, the supraglottis has been reported to be the commonest subsite in developing countries, including examples in the Indian subcontinent. To our knowledge, no study has been carried out in western Nepal about the epidemiology of laryngeal cancer to date. The purpose of this study was to analyse the epidemiology of laryngeal cancer in relation to its risk factors, age distribution,and preferred subsites and to see if there is any recent change in the subsite wise distribution of laryngeal malignancy in western Nepal. MATERIALS AND METHODS: Patients of all ages and both sexes with suspected laryngeal malignancy were enrolled in the initial study. Detailed history taking and clinical examination was performed to find out the involved subsite in relation to the clinical features. Direct laryngoscopy was performed to further confirm the subsite and to take biopsy from the growth under general anesthesia. After confirmation of malignancy from the biopsy report, patients were finally included in the study. Data were analysed and observations were made to find out the distribution of laryngeal malignancy in different subsites. RESULTS: The supraglottic larynx was the commonest subsite to harbor laryngeal malignancy. Smoking and alcohol were found to be the common risk factors. The mean age of the patients was in their sixties. CONCLUSIONS: Laryngeal malignancy is common in elderly individuals. Supraglottic laryngeal malignancy is the commonest laryngeal malignancy in people who smoke and drink alcohol in Nepal. Avoidance of alcohol use and smoking will be a milestone to reduce the incidence of laryngeal cancers and associated mortality.