Clarifying the Dopant Local Structure and Effect on Ionic Conductivity in Garnet Solid-State Electrolytes for Lithium-Ion Batteries

The high Li-ion conductivity and wide electrochemical stability of Li-rich garnets (Li7La3Zr2O12) make them one of the leading solid electrolyte candidates for solid-state batteries. Dopants such as Al and Ga are typically used to enable stabilization of the high Li+ ion-conductive cubic phase at room temperature. Although numerous studies exist that have characterized the electrochemical properties, structure, and lithium diffusion in Al- and Ga-LLZO, the local structure and site occupancy of dopants in these compounds are not well understood. Two broad 27Al or 69,71Ga resonances are often observed with chemical shifts consistent with tetrahedrally coordinated Al/Ga in the magic angle spinning nuclear magnetic resonance (MAS NMR) spectra of both Al- and Ga-LLZO, which have been assigned to either Al and/or Ga occupying 24d and 96h/48g sites in the LLZO lattice or the different Al/Ga configurations that arise from different arrangements of Li around these dopants. In this work, we unambiguously show that the side products γ-LiAlO2 and LiGaO2 lead to the high frequency resonances observed by NMR spectroscopy and that both Al and Ga only occupy the 24d site in the LLZO lattice. Furthermore, it was observed that the excess Li often used during synthesis leads to the formation of these side products by consuming the Al/Ga dopants. In addition, the consumption of Al/Ga dopants leads to the tetragonal phase formation commonly observed in the literature, even after careful mixing of precursors. The side-products can exist even after sintering, thereby controlling the Al/Ga content in the LLZO lattice and substantially influencing the lithium-ion conductivity in LLZO, as measured here by electrochemical impedance spectroscopy.

Understanding the Surface Regeneration and Reactivity of Garnet Solid-State Electrolytes

Garnet solid-electrolyte-based Li-metal batteries can be used in energy storage devices with high energy densities and thermal stability. However, the tendency of garnets to form lithium hydroxide and carbonate on the surface in an ambient atmosphere poses significant processing challenges. In this work, the decomposition of surface layers under various gas environments is studied by using two surface-sensitive techniques, near-ambient-pressure X-ray photoelectron spectroscopy and grazing incidence X-ray diffraction. It is found that heating to 500 °C under an oxygen atmosphere (of 1 mbar and above) leads to a clean garnet surface, whereas low oxygen partial pressures (i.e., in argon or vacuum) lead to additional graphitic carbon deposits. The clean surface of garnets reacts directly with moisture and carbon dioxide below 400 and 500 °C, respectively. This suggests that additional CO2 concentration controls are needed for the handling of garnets. By heating under O2 along with avoiding H2O and CO2, symmetric cells with less than 10 Ωcm2 interface resistance are prepared without the use of any interlayers; plating currents of >1 mA cm-2 without dendrite initiation are demonstrated.

Surface reduction in lithium- and manganese-rich layered cathodes for lithium ion batteries drives voltage decay

Li- and Mn-rich layered oxides (Li_1.2Ni_0.2Mn_0.6O₂) are actively pursued as high energy and sustainable alternatives to the current Li-ion battery cathodes that contain Co. However, the severe decay in discharge voltage observed in these cathodes needs to be addressed before they can find commercial applications. A few mechanisms differing in origin have been proposed to explain the voltage fade, which may be caused by differences in material composition, morphology and electrochemical testing protocols. Here, these challenges are addressed by synthesising Li_1.2Ni_0.2Mn_0.6O₂ using three different hydrothermal and solid-state approaches and studying their degradation using the same cell design and cycling protocols. The voltage fade is found to be similar under the same electrochemical testing protocols, regardless of the synthesis method. X-ray absorption near edge, extended X-ray absorption fine structure spectroscopies, and energy loss spectroscopy in a scanning transmission electron microscope indicate only minor changes in the bulk Mn oxidation state but reveal a much more reduced particle surface upon extended cycling. No spinel phase is seen via the bulk structural characterisation methods of synchrotron X-ray diffraction, ⁷Li magic angle spinning solid state nuclear magnetic resonance and Raman spectroscopy. Thus, the voltage fade is believed to largely result from a heavily reduced particle surface. This hypothesis is further confirmed by galvanostatic intermittent titration technique analysis, which indicates that only very small shifts in equilibrium potential take place, in contrast to the overpotential which builds up after cycling. This suggests that a major source of the voltage decay is kinetic in origin, resulting from a heavily reduced particle surface with slow Li transport.

A study on the effects of stress and hopelessness in isolated COVID-19 patients in relation to severity of infection

Introduction

In India, Coronavirus pandemic started in the month of march 2020 and is growing day by day. In view of India being one of the most populous countries, it is hard to follow social distancing and abide by the lockdown rules. Therefore, as of December 2020, total number of covid-19 cases has crossed the 10 million. But the recovery rate in India is high, so the fear due to Covid-19 has decreased in intensity.

Objectives

To assess level of perceived stress in isolated covid-19 patients To assess level of hopelessness in isolated covid-19 patients

Methods

30 Patients of diagnosed Covid-19 positive,who were isolated in covid care setting in Uttar Pradesh(India),above 18yrs of age,of both sexes and willing to participate in the study were included, their socio-demographic data collected. Beck’s hopelessness scale and Perceived stress scale were administered. Infection severity upto moderate was selected and ICU patients were excluded. Results were analysed using SPSS software.

Results

It was observed that level of hopelessness increased with increasing age and increasing severity of covid-19.Level of perceived stress also increased with increasing age and increasing covid severity. There was no relation seen between hopelessness level and perceived stress level and no difference was seen in the levels of hopelessness and perceived stress between the two sexes.

Conclusions

Levels of hopelessness and stress increased with increasing age and increasing severity of covid-19.No relation seen between hopelessness level and perceived stress level and no difference was seen in the levels of hopelessness and perceived stress between the two sexes.

Disclosure

No significant relationships.

Comparative study of caregiver stress between patients of obsessive compulsive disorder and chronic medical illness, without any physical disability

Introduction

Obsessive compulsive disorder (OCD) is a disabling condition that affects the quality of life of both the patient and the caregivers. Similarly, in patients with physical medical illness, caregivers face a significant amount of stress.

Objectives

This study aimed to assess and compare the caregiver strain index between patients of OCD and medical illness. Moreover, this study will also compare the care giver strain index in the patients of OCD and physical medical illness depending on the severity and duration of the illness.

Methods

Study was done at Department of psychiatry, Teerthanker Mahaveer University, Moradabad. In this Cross-sectional study 2 groups of caregivers were included. The group 1 included 30 caregivers of obsessive compulsive disorder patients and group 2 included 30 caregivers for physical medical illness. The Yale-Brown Obsessive Compulsive Scale was used for measuring the severity of OCD and the stress in caregivers were drawn from Caregiver strain index.

Results

This study reported a high objective burden among caregivers of OCD compared with the physical medical illness (P-value=0.002). The age of the caregivers also showed to be significantly associated with the stress in both the groups. The severity of the OCD was shown to be correlated well with the stress of the caregivers (P-value=0.032). In contrast, in physical medical illness the duration of the disease showed no significant association with the caregiver’s stress.

Conclusions

This study showed that in patients with OCD caregivers face a higher strain compared with the physical medical illness.

Disclosure

No significant relationships.

Synthesis, polytypism, and dehydration behaviour of nitrate-intercalated layered double hydroxides of Ca and Al

Rapid and controlled precipitation of the hydroxide phases from a mixed metal nitrate solution comprising Ca²⁺ and Al³⁺ ions leads to the formation of 1H and 3R polytypes of [Ca–Al] layered double hydroxide respectively.

Non-EPI-DWI for Detection, Disease Monitoring, and Clinical Decision-Making in Thyroid Eye Disease

BACKGROUND AND PURPOSE

The Clinical Activity Score is widely used to grade activity of thyroid eye disease and guide treatment decisions, but as a subjective measurement and being confined to the anterior orbit, it has limitations. Non-EPI-DWI of the extraocular muscles may offer advantages as a functional imaging technique with reduced skull base artifacts, but the correlation with the Clinical Activity Score and patient outcome is unknown. Our aim was to establish the correlation between the Clinical Activity Score and non-EPI-DWI and to describe the additional value provided by adjunctive non-EPI-DWI in making clinical decisions.

MATERIALS AND METHODS

This was a retrospective longitudinal study of 31 patients seen in a multidisciplinary thyroid eye disease clinic during 5 years who had at least 1 ophthalmic and endocrine assessment including the Clinical Activity Score and a non-EPI-DWI ADC calculation. The Spearman rank correlation coefficient was used to determine the relationship between the Clinical Activity Score and non-EPI-DWI. A patient flow chart was constructed to evaluate clinical decision-making, and receiver operating characteristics were generated.

RESULTS

From 60 non-EPI-DWI scans, 368 extraocular muscles were selected for analysis. There was a significant positive correlation between the Clinical Activity Score and ADC (r _s = 0.403; 95% CI, 0.312-0.489; P < .001). ADC values were significantly higher in the Clinical Activity Score ≥ 3 group compared with the Clinical Activity Score < 3 group (P < .001). Our patient flow chart identified a third intermediate-severity cohort in which the non-EPI-DWI was particularly useful in guiding clinical decisions.

CONCLUSIONS

The non-EPI-DWI correlated well with the Clinical Activity Score in our patients and was a useful adjunct to the Clinical Activity Score in making clinical decisions, especially in patients with intermediate activity and severity of thyroid eye disease.

Synthon Approach to Structure Models for the Bayerite-Derived Layered Double Hydroxides of Li and Al

The Br^- ion intercalated layered double hydroxide (LDH) of Li and Al obtained from the bayerite-Al(OH)₃ precursor crystallizes in a structure different from that of the gibbsite-Al(OH)₃ derived counterpart. Additionally, it undergoes temperature- and humidity-induced reversible interpolytype transformations. The dehydrated LDH (T ≈ 120 °C) adopts a structure of hexagonal symmetry (space group P3̅1m) and comprises a stacking of the metal hydroxide layers arranged one above another. On cooling and rehydration, the LDH adopts a structure of monoclinic symmetry with a stepwise increase in the stacking angle, β. Using the structural synthon approach, based on the systematic elimination of the principal symmetry elements of the hexagonal crystal, structure models were generated for each of the two hydration steps (relative humidity ∼50%, >70%) and the structures refined (space group C2/m). The refined structures show that the interpolytype transitions are a result of rigid translations of successive metal hydroxide layers relative to one another by translation vectors (1/6, 0, 1) and (1/3, 0, 1), respectively.

Triphenylbenzene Sensor for Selective Detection of Picric Acid

A C ₃-symmetric triphenylbenzene based photoluminescent compound, 1,3,5-tris(4'-(N-methylamino)phenyl) benzene ([NHMe]₃TAPB), has been synthesized by mono-N-methylation of 1,3,5-tris(4'-aminophenyl) benzene (TAPB) and structurally characterized. [NHMe]₃TAPB acts as a selective fluorescent sensor for picric acid (PA) with a detection limit as low as 2.25 ppm at a signal to noise ratio of 3. Other related analytes (i.e. TNT, DNT and DNB) show very little effect on the fluorescence intensity of [NHMe]₃TAPB. The selectivity is triggered by proton transfer from picric acid to the fluorophore and ground-state complex formation between the protonated fluorophore and picrate anion through hydrogen bonding interactions. The fluorescence lifetime measurements reveal static nature of fluorescence quenching.

Structure models for the hydrated and dehydrated nitrate-intercalated layered double hydroxide of Li and Al

Imbibition of LiNO₃ into gibbsite results in the formation of a single phase layered double hydroxide of the composition LiAl₂(OH)₆(NO₃)·1.2H₂O. This phase undergoes reversible dehydration along with the compression of the basal spacing accompanied by the reorientation of the nitrate in the interlayer gallery. The hydrated phase is a solid solution of two lattices: (i) a hexagonal lattice defining the ordering of atoms within the metal hydroxide layer, and (ii) a lattice of orthorhombic symmetry defining the ordering of atoms within the interlayer. DFT calculations of the hydration behaviour show that there is no registry between the two sublattices. In the dehydrated phase, the nitrate ion is intercalated with its molecular plane parallel to the metal hydroxide layer and the crystal adopts a structure of hexagonal symmetry.

Management of invasive cervical resorption in a maxillary central incisor

Invasive cervical resorption is often not diagnosed properly, leading to improper treatment or unnecessary loss of the tooth structure. Early diagnosis and appropriate treatment are the keys to a successful outcome of therapy. Invasive cervical resorption is often seen in the cervical area of the tooth, but because it is initiated apical to the epithelial attachment, it can present anywhere in the root. In the early stages, it may be symmetrical, but larger lesions have the tendency to be asymmetrical. It can expand apically or coronally.

Layered Double Hydroxides: Proposal of a One-Layer Cation-Ordered Structure Model of Monoclinic Symmetry

Layered double hydroxides are obtained by partial isomorphous substitution of divalent metal ions by trivalent metal ions in the structure of mineral brucite, Mg(OH)2. The widely reported three-layer polytype of rhombohedral symmetry, designated as polytype 3R1, is actually a one-layer polytype of monoclinic symmetry (space group C2/m, a = 5.401 Å, b = 9.355 Å, c = 11.02 Å, β = 98.89°). This structure has a cation-ordered metal hydroxide layer defined by a supercell a = √3 × a0; b = 3 × a0 (a0 = cell parameter of the cation-disordered rhombohedral cell). Successive layers are translated by (1/3, 0, 1) relative to one another. When successive metal hydroxide layers are translated by (2/3, 0, 1) relative to one another, the resultant crystal, also of monoclinic symmetry, generates a powder pattern corresponding to the polytype hitherto designated as 3R2. This structure model not only removes all the anomalies intrinsic to the widely accepted cation-disordered structure but also abides by Pauling's rule that forbids trivalent cations from occupying neighboring sites and suggests that it is unnecessary to invoke rhombohedral symmetry when the metal hydroxide layer is cation ordered. These results have profound implications for the correct description of polytypism in this family of layered compounds.

Towards comprehensive population-based screening for diabetic retinopathy: operation of the North Wales diabetic retinopathy screening programme using a central patient register and various screening methods

OBJECTIVES

To examine whether population-based retinopathy screening using a central diabetes register and employing various screening methods can achieve a high degree of population coverage to meet National Screening Committee (NSC) targets. To identify the main barriers to achieving comprehensive population coverage. To analyse referrals to ophthalmology and their outcome as a measure of previously unmet need. To assess the influence of modality of screening.

SETTING

Three local health board areas in North Wales.

METHODS

Establishment of a district diabetes register to hold records of all patients and subserve call-recall of general practitioner (GP) sole-care patients for screening by optometrists or digital photography. Hospital attenders were screened in diabetic clinic by direct ophthalmoscopy. Data were collected for years 1 and 2 of operation of the scheme.

RESULTS

The system held a screening record for 86% of diabetic patients after year 1 and 93% after year 2. Failure to attend was the major barrier to comprehensive population screening, but this improved in year 2 (P<0.001). Both optometrists and photography identified substantial unmet need: 1% of all GP sole-care patients required immediate laser treatment. Photography was more sensitive than optometrist screening, but the additional retinopathy identified was mostly minor not requiring treatment.

CONCLUSIONS

Lack of screening is much more important than modality of screening as a cause of missed sight-threatening retinopathy. A central, district-based patient register system identifies those patients not screened for further follow-up and can produce a high level of population coverage, close to NSC targets. Such schemes are needed, particularly to support primary care diabetes management.

Is telemedicine a subset of medical informatics?

Informatics has a key characteristic of a new discipline in a technically transient environment--there is no universal definition of it. This is not surprising, given its complex and diverse nature. In a broad sense informatics is the interface between developing technologies and the decision sciences, in particular clinical sciences. Telemedicine has no universally accepted definition either. Telemedicine requires the use of electronic communication networks for the transmission of information and data related to the diagnosis and treatment of, as well as education about, medical conditions. The debate ensues over whether it is or is not a subset of medical informatics. The care of the elderly diploma programme is a telemedicine project within the department of family medicine at the University of Alberta; it is a distance learning programme directed towards educating and training physicians in rural Alberta. This project provided us with the practical experience of addressing both informatics and telemedicine issues jointly.

Primary biphasic synovial sarcoma of the orbit

Synovial sarcoma is one of the most common soft tissue malignancies of adolescents and young adults. Despite its name, it is no longer thought to be histogenetically derived from the synovium. What seems to be the first case of synovial sarcoma to arise in the orbit presented in a 21 year old woman as a slowly enlarging subconjunctival mass. Although this tumour was typically biphasic, the monophasic spindle cell variant arising at this site could easily be confused with less aggressive orbital connective tissue neoplasms.