Exciton dynamics in two-dimensional metal halide perovskite: The impact of film processing.

We investigate the hot carrier and exciton dynamics in two-dimensional (2D) metal halide perovskites using time-resolved spectroscopy. 2D perovskite films were prepared with and without dimethyl sulfoxide treatment to elucidate the effect of film processing techniques on optoelectronic properties. Femtosecond transient absorption measurements reveal that the charge carrier dynamics are different in the two samples, and excitons survive for a longer time in the treated sample than the untreated one. While the early-time carrier dynamics in the untreated sample are dominated by charges trapped by defect states, the hot free carriers govern the dynamics in the treated sample due to fewer defects in it. Morphological and other spectroscopic studies, including time-resolved photoluminescence, further suggest the formation of more defects in the untreated sample. These results can guide the future development of efficient 2D perovskite-based optoelectronic devices.

Development of ASTM International D8405-Standard Test Method for Evaluating PM2.5 Sensors or Sensor Systems Used in Indoor Applications.

Sensors and sensor systems for monitoring fine particles with aerodynamic diameters smaller than 2.5 µm can provide real-time feedback on indoor air quality and thus can help guide actions to manage indoor air pollutant concentrations. Standardized verification of the performance and accuracy of sensors and sensor systems is crucial for predicting the efficacy of such monitoring. A new ASTM International standard test method (ASTM D8405) was created for this need and is the most exacting laboratory protocol published to date for evaluating indoor air quality sensors and sensor systems measuring particles smaller than 2.5 µm in diameter. ASTM D8405 subjects sensors and sensor systems to five test phases: (1) an initial particle concentration ramp; (2) exposure to various temperature and humidity conditions; (3) exposure to interfering particles; (4) temperature cycling; and (5) a final particle concentration ramp to assess drift. This paper discusses the development of the standard test method, key aspects of the testing process, example evaluation results, and a comparison of this standard test method against peer evaluation protocols.

Surface Passivation by Sulfur-Based 2D (TEA)2PbI4 for Stable and Efficient Perovskite Solar Cells.

Perovskite solar cells (PSCs) with superior performance have been recognized as a potential candidate in photovoltaic technologies. However, defects in the active perovskite layer induce nonradiative recombination which restricts the performance and stability of PSCs. The construction of a thiophene-based 2D structure is one of the significant approaches for surface passivation of hybrid PSCs that may combine the benefits of the stability of 2D perovskite with the high performance of three-dimensional (3D) perovskite. Here, a sulfur-rich spacer cation 2-thiopheneethylamine iodide (TEAI) is synthesized as a passivation agent for the construction of a three-dimensional/two-dimensional (3D/2D) perovskite bilayer structure. TEAI-treated PSCs possess a much higher efficiency (20.06%) compared to the 3D perovskite (MA0.9FA0.1PbI3) devices (17.42%). Time-resolved photoluminescence and femtosecond transient absorption spectroscopy are employed to investigate the effect of surface passivation on the charge carrier dynamics of the 3D perovskite. Additionally, the stability test of TEAI-treated perovskite devices reveals significant improvement in humid (RH ∼ 46%) and thermal stability as the sulfur-based 2D (TEA)2PbI4 material self-assembles on the 3D surface, making the perovskite surface hydrophobic. Our findings provide a reliable approach to improve device stability and performance successively, paving the way for industrialization of PSCs.

Retrospective analysis of low vision assistive products - A 6-year review.

PURPOSE: The purpose of the study was to analyze the demographics, visual acuity (VA), etiologies, recommended low vision assistive products (LVAP), and the acceptance rates of LVAP in various age groups. METHODS: This was a long-term retrospective review of all the patients presenting to the low vision clinic of our tertiary eye care hospital from January 2011 to December 2016. Data obtained included age, gender, VA, visual fields, ocular pathology causing the low vision, and types of LVAP advised. The primary outcome was to analyze the type of LVAP prescribed in different age groups, and the secondary outcome was the acceptance rate of LVAP. RESULTS: We analyzed the results of 8309 patients, out of which 2844 (34%. 2) were <15 years of age, 2425 (29.5%) were between 16-40 years, and 3013 (36.3%) were above 40 years. A total of 5522 (66.4%) had best-corrected visual acuity (BCVA) ranging from 6/18-3/60, and 2796 (33.6%) had BCVA from 3/60-No PL. Approximately 38% improved with LVAPs. The most common etiology was retinitis pigmentosa in 1545 (18.6%) patients, followed by congenital nystagmus in 1482 (17.8%), and the least was albinism 383 (4.6%). Maximum prescribed and accepted LVAP were hand and stand magnifiers among 1017 (44.3%) and 512 (52.6%) patients, respectively. CONCLUSION: Products that are easy to use, require lesser adaptability, are cheap, and require lower maintenance have maximum acceptance rates. We suggest that great emphasis should be laid on training, education, and guidance for low vision rehabilitation centers.

Causation, historiographic approaches and the investigation of serious adverse incidents in mental health settings.

To improve the safety of healthcare systems, it is necessary to understand harm-related events that occur in these systems. In mental health services, particular attention is paid to harm arising from the actions of patients against themselves or others. The primary intention of examining these adverse events is to inform changes to care provision so as to reduce the likelihood of the recurrence of such events. The predominant approach to investigating adverse incidents has relied on the cause-and-effect conceptualisation of past events. Whilst the merits of approaches which are reliant on cause-and-effect narratives have been questioned, alternatives models to explain adverse incidents in health settings have not been theoretically or empirically tested. This novel article (i) examines the notion of causation (and the related notion of omission) in the context of explaining adverse events in mental health settings, and (ii) draws on a long-established discipline devoted to the study of how the past is interpreted (namely historiography) to theoretically investigate the innovative application of two historiographical approaches (i.e. counterfactual analysis and historical materialism) to understanding adverse events in mental health settings.

Comparison of the outcomes of phacoemulsification and manual small-incision cataract surgery in posterior polar cataract - A retrospective study.

Purpose: To compare the visual outcomes and intraoperative complications between phacoemulsification and manual small-incision cataract surgery (MSICS) in cases of posterior polar cataract (PPC). Methods: A retrospective study was carried out involving 142 patients (164 eyes) with PPC who underwent cataract surgery between January and December 2017. Data collected include the demographic details, preoperative uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), type of cataract, intraocular pressure, anterior and posterior segment findings, type of surgery performed, intraoperative complications, postoperative UCVA on the first day, UCVA and BCVA at 1 month after surgery, complications, and resurgery details. Results: In total, 90 patients (107 eyes) underwent phacoemulsification, and 52 patients (57 eyes) underwent MSICS. There was no significant difference in the mean age, sex, and type of PPC between the two groups (P = 0.326, 0.852, and 0.220, respectively). Patients who underwent phacoemulsification had significantly better preoperative BCVA (P = 0.002). The BCVA on first postoperative day and 1 month after surgery was better in the phacoemulsification group than in the MSICS group (P < 0.001 and 0.002, respectively). The overall incidence of posterior capsular rupture (PCR) was 11.6%, which included the 10.3% in phacoemulsification and 14.0% in MSICS. There was, however, no significant difference in the rates of PCR between the two groups (P = 0.506). Conclusion: Phacoemulsification delivered better postoperative visual outcomes than MSICS in PPC patients, whereas the complication rates were similar between the two groups.

Mentor-mentee relationship in ophthalmology - Following the footsteps of stalwarts.

Mentor- mentee relationship in any discipline is a professional and interpersonal relationship. It associates a mentor with a protégé or a mentee. Mentoring is a serious business in Ophthalmology, both academically and surgically. The mentors act as role models for future generations by acting as a friend, coach, or guide to the mentee. They do so by giving valuable advice, moral support, and inculcating skills in a mentee. It is difficult to pinpoint the precise function of the mentor-mentee relationship, but the final goal is to achieve personal and professional objectives. In the current article, the authors have shed light on the imperative aspect of one's Ophthalmology career, i.e., the mentor-mentee relationship. This article describes various aspects of mentoring, the traits of a perfect mentor and mentee, the pre-requisites for a good mentee-mentor relationship, the hindrances and obstacles in a good relationship, and the impact of COVID-19 on the same. The potential goal of this article is to ignite the constructive spirit of the mentor-mentee relationship, encourage potential mentors to become ideal mentors, and potential mentees to gain from serious mentors.

Cannabis Cultivation Facilities: A Review of Their Air Quality Impacts from the Occupational to Community Scale.

This review addresses knowledge gaps in cannabis cultivation facility (CCF) air emissions by synthesizing the peer-reviewed and gray literature. Focus areas include compounds emitted, air quality indoors and outdoors, odor assessment, and the potential health effects of emitted compounds. Studies suggest that ß-myrcene is a tracer candidate for CCF biogenic volatile organic compounds (BVOCs). Furthermore, ß-myrcene, d-limonene, terpinolene, and α-pinene are often reported in air samples collected in and around CCF facilities. The BVOC emission strength per dry weight of plant is higher than most conventional agriculture crops. Nevertheless, reported total CCF BVOC emissions are lower compared with VOCs from other industries. Common descriptors of odors coming from CCFs include "skunky", "herbal", and "pungent". However, there are few peer-reviewed studies addressing the odor impacts of CCFs outdoors. Atmospheric modeling has been limited to back trajectory models of tracers and ozone impact assessment. Health effects of CCFs are mostly related to odor annoyance or occupational hazards. We identify 16 opportunities for future studies, including an emissions database by strain and stage of life (growing cycle) and odor-related setback guidelines. Exploration and implementation of key suggestions presented in this work may help regulators and the industry reduce the environmental footprint of CCF facilities.

Acute isolated medial rectus palsy due to infarction as a result of hypercoagulable state: A case report and literature review.

Isolated medial rectus palsy in an otherwise healthy individual is a very rare entity. However, this may point towards underlying systemic pathology. This is a case report of an otherwise healthy young adult male who presented with sudden onset non-progressive blurring of vision in right eye. A series of investigations were performed and the patient was diagnosed to have a rheumatological disorder. Isolated muscle palsies in young patient may be masking a systemic disorder and needs to be evaluated thoroughly.

Identification of peptide coatings that enhance diffusive transport of nanoparticles through the tumor microenvironment.

In solid tumors, increasing drug penetration promotes their regression and improves the therapeutic index of compounds. However, the heterogeneous extracellular matrix (ECM) acts as a steric and interaction barrier that hinders effective transport of therapeutics, including nanomedicines. Specifically, the interactions between the ECM and surface physicochemical properties of nanomedicines (e.g. charge, hydrophobicity) affect their diffusion and penetration. To address the challenges using existing surface chemistries, we used peptide-presenting phage libraries as a high-throughput approach to screen and identify peptides as coatings with desired physicochemical properties that improve diffusive transport through the tumor microenvironment. Through iterative screening against the ECM and identification by next-generation DNA sequencing and analysis, we selected individual clones and quantify their transport by diffusion assays. Here, we identified a net-neutral charge, hydrophilic peptide P4 that facilitates significantly higher diffusive transport of phage than negative control through in vitro tumor ECM. Through alanine mutagenesis, we confirmed that the hydrophilicity, charge, and spatial ordering impact diffusive transport. The P4 phage clone exhibited almost 200-fold improved uptake in ex vivo pancreatic tumor xenografts compared to the negative control. Nanoparticles coated with P4 exhibited ∼40-fold improvement in diffusivity in pancreatic tumor tissues, and P4-coated particles demonstrated less hindered diffusivity through the ECM compared to functionalized control particles. By leveraging the power of molecular diversity using phage display, we can greatly expand the chemical space of surface chemistries that can improve the transport of nanomedicines through the complex tumor microenvironment to ultimately improve their efficacy.

Retrospective study on outcomes of terminal chop technique of nuclear fragmentation in phacoemulsification and combined surgery: An observational study.

PURPOSE: Terminal chop, a new technique of nuclear segmentation, has been recently described in literature. The technique is considered to be a safe and effective option. METHODS: We did a retrospective study to evaluate the outcome of terminal chop. Patients operated for terminal chop (phacoemulsification with or without trabeculectomy) from October 2016 to July 2018 were included in the study. RESULTS: In all, 933 patients were included in the study. The grade of nuclear sclerosis ranged from 2 to 5. All the patients had a significant visual improvement at 1 month postop. Around 3.4% had pseudoexfoliation and 8.89% of the eyes underwent combined surgery. Cumulative dissipated energy showed a proportionate relation with the grade of nucleus. Intraoperative complication rate was 0.08%. Postoperative complication rate was 3.50%. CONCLUSION: Terminal chop proved to be a safe, reproducible, and effective technique of nuclear segmentation in different grades of cataract.

POSTERIOR VITRECTORHEXIS: A SURGICAL MODIFICATION FOR INTRAOCULAR FOREIGN BODY REMOVAL THROUGH LIMBAL ROUTE.

PURPOSE: To describe a modified surgical technique of creating a posterior capsule opening for removal of retained intraocular foreign body, what we call as retroillumination-assisted posterior vitrectorhexis. METHODS: Vitrectomy probe through pars plana route is used to create a well-controlled circular posterior vitrectorhexis. RESULTS: A uniformly circular posterior capsule opening is created after standard pars plana vitrectomy for the removal of foreign body. CONCLUSION: Posterior vitrectorhexis is a well-controlled technique in the setting of a penetrating injury that can facilitate safe removal of different sizes of intraocular foreign body simultaneously preserving capsular support.

Formation of Particulate Matter from the Oxidation of Evaporated Hydraulic Fracturing Wastewater.

The use of hydraulic fracturing for production of petroleum and natural gas has increased dramatically in the past decade, but the environmental impacts of this technology remain unclear. Experiments were conducted to quantify airborne emissions from 12 samples of hydraulic fracturing flowback wastewater collected in the Permian Basin, as well as the photochemical processing of these emissions leading to the formation of particulate matter (PM). The concentration of total volatile carbon (hydrocarbons evaporating at room temperature) averaged 29 mg of carbon per liter. After photochemical oxidation under high NO x conditions, the amount of organic PM formed per milliliter of wastewater evaporated averaged 24 µg; the amount of ammonium nitrate formed averaged 262 µg. Based on the mean PM formation observed in these experiments, the estimated formation of PM from evaporated flowback wastewater in the state of Texas is in the range of estimated PM emissions from diesel engines used in oil rigs. Evaporation of flowback wastewater, a hitherto unrecognized source of secondary pollutants, could significantly contribute to ambient PM concentrations.

Extraocular needle- guided haptic insertion technique of scleral fixation intraocular lens surgeries (X-NIT).

The most challenging step in sutureless scleral fixation of intraocular lens (SFIOL) is exteriorization of haptics. The conventional handshake technique has a learning curve since it involves intraocular handing over of haptics from one forceps to another. Here, we describe "extraocular needle-guided haptic insertion technique" (X-NIT), a novel technique of exteriorizing haptics that totally eliminates intraocular manipulations. This method involves sequential introduction of two bent 26-gauge needles through the sclera (pars plicata zone) into the eye which are brought out through a sclerocorneal wound. The intraocular lens haptics are threaded through these needles and exteriorized. Nineteen consecutive patients underwent surgery by this technique. There were no intraoperative complications. The mean best-corrected visual acuity (BCVA) of these patients at 1-month follow-up was 0.5 ± 0.3 (logarithm of the minimum angle of resolution) with 18 of 19 eyes showing one or more lines of improvement in BCVA. X-NIT is a safe, easy, cost-effective, and highly reproducible technique, especially for beginners.

Publication rates from the All India Ophthalmic Conference 2010 compared to 2000: Are we improving?

PURPOSE: To determine the publication rates of free papers and posters presented at the All India Ophthalmic Conference (AIOC) 2010 in peer-reviewed journals up to December 2015 and compare this with publication rates from AIOC2000 published previously. METHODS: A thorough literature search was conducted using PubMed, Google Scholar, and the general Google search engine by two independent investigators. The title of the paper, keywords and author names were used to "match" the AIOC free-paper with the published paper. In addition, the "purpose," "methods," and "outcome measures" between the two were studied to determine the "match." RESULTS: A total of 58 out of 394 free-papers (14.7%) from AIOC2010 were published till December 2015 compared to 16.5% from AIOC2000. Out of these, 52 (90%) were published in PubMed indexed journals. Maximum publications were seen in pediatric ophthalmology (50%) followed by glaucoma (24.4%) and cornea (23.8%). Fifteen out of 272 posters (5.5%) were published; orbit/oculoplastics had the highest poster publications (13%). Excluding papers in nonindexed journals and those by authors with international affiliations, the publication rate was approximately 12%. CONCLUSION: The publication rate of free papers from AIOC2010 has marginally reduced compared to AIOC2000. Various causes for this such as lack of adequate training, motivation, and lack of incentives for research in the Indian scenario have been explored, and measures to improve this paradigm have been discussed. It will be prudent to repeat this exercise every decade to compare publication rates between periodic AIOC, stimulate young minds for quality research and educate policy makers toward the need for developing dedicated research departments across the country.

Anterior stromal puncture with staining: A modified technique for preoperative reference corneal marking for toric lenses and its retrospective analyses.

INTRODUCTION: Toric intraocular lenses (IOLs) are an effective way of compensating preexisting corneal astigmatism during cataract surgery. To achieve success, it is imperative to align the toric IOLs in desired position and preoperative reference marking is one among the three important steps for accurate alignment. To make the marking procedure simpler and effective, we have modified the conventional three-step slit lamp-based technique. MATERIALS AND METHODS: Patient is seated in front of the slit lamp and asked to keep the chin over chin rest. A 26-gauge bent needle with tip stained by sterile blue ink marker is used to make anterior stromal puncture (ASP) at the edges of horizontal 180° axis near the limbus. RESULTS: A total of 58 eyes were retrospectively evaluated. Mean (+/-SD) IOL deviation on day 1 and day 30 was 5.7 ± 6.5° and 4.7 ± 5.6°, respectively. Median IOL misalignment on day 1 and day 30 was 3°. Redialing of IOL was required in 2 (3.4%) eyes only, all of which were performed within 1 week of surgery. In total, 2 (3.7%) eyes had a residual astigmatism of - 0.5 Dcyl and - 1.0 Dcyl, respectively. CONCLUSION: ASP is an effective technique for reference marking, technically simpler and can be practiced by most of the surgeons. It avoids the necessity of high-end sophisticated machinery and gives a better platform for the reference corneal marking along with the benefit of reproducibility and simplicity.

Measurement, Classification and Evaluation of Sleep Disturbance in Psoriasis: A Systematic Review.

BACKGROUND: Psoriasis is a long-term immune-mediated inflammatory disorder mainly, but not only, affecting skin, and is associated with significant medical and psychological morbidity. Evidence suggests that sleep is disrupted in psoriasis, however high quality empirical evidence is lacking. Given the importance of sleep for health, characterisation of sleep disruption in psoriasis is an important goal. We therefore conducted a systematic review of the sleep-psoriasis literature. METHODS: Searches were conducted in Pubmed, SCOPUS and Web of Science from inception to May 2016. Studies were compared against inclusion/exclusion criteria and underwent a quality evaluation. Given the heterogeneity of studies, we conducted a narrative synthesis of the findings. RESULTS: Searches revealed 32 studies which met our predetermined inclusion/exclusion criteria. Whilst 93.7% of studies reported sleep disruption in this population, ranging from 0.05% to 85.4%, many had important methodological shortcomings. Over half of all quantitative studies (54.8%; 17/31) relied on non-validated measures, contributing to heterogeneity in study findings. In those that employed valid measures, assessing sleep was often not the primary objective. We frequently found the absence of adequate sample size calculations and poor statistical reporting. CONCLUSION: This review showed that in psoriasis, reported sleep rates of sleep disturbance varied substantially. Most studies lacked a hypothesis driven research question and/or failed to use validated measures of sleep. We were unable to draw firm conclusions about the precise prevalence and nature of sleep disturbance within the psoriasis population. We offer suggestions to help advance understanding of sleep disturbance in psoriasis.

Factors affecting treatment outcome in congenital nasolacrimal duct obstruction: A retrospective analysis from South India.

PURPOSE: To investigate outcomes for different treatment modalities in congenital nasolacrimal duct obstruction (CNLDO) in an Indian population. DESIGN: Retrospective, interventional, case series. MATERIALS AND METHODS: In an institutional setting, case records of patients with CNLDO from January 2008 to 2012, were reviewed, and data on patient demographics, clinical presentation, and treatment details (sac massage, probing, and/or dacryocystorhinostomy) were recorded. Success of treatment was defined as complete resolution of symptoms and negative regurgitation on pressure over lacrimal sac (ROPLAS) area. RESULTS: Two hundred and ninety-eight eyes of 240 patients with a mean age of 22.2 ± 26.14 months (median = 12 months, interquartile range = 17) were analyzed. Sac massage (n = 226) was successful in 67 eyes (30%). Multivariable logistic regression analyses showed that children with mucoid ROPLAS were almost 6 times more likely (odds ratio [OR] = 5.55 vs. clear ROPLAS, 95% confidence interval [CI] = 2.35-13.09, P < 0.001) to experience failure of sac massage. Overall probing (n = 193) was successful for 143 (74%) eyes. Multivariable logistic regression showed that older children were 25% more likely to experience probing failure (OR = 1.25 for every 6 months increment in age, 95%, CI = 1.09-1.42, P = 0.001). CONCLUSION: Sac massage is successful in only a third of our patients and those with mucoid ROPLAS are more likely to experience failure. Probing is successful in three-quarter of our subjects, and its success declines with a progressive increase in age. Lower socioeconomic status, poor general health, and recurrent respiratory infections are unique to our population and may influence outcomes.

The role of compression in the management of soft tissue ankle injuries: a systematic review.

BACKGROUND: Ankle sprains are very common injuries which can lead to long-term pain, swelling and instability. Compression is often used in the treatment of these common injuries but is it effective and how best is it delivered? METHODS: MEDLINE (1966-current), EMBASE (1980-current), Cochrane Library (2011:1) and MEDION were included in our search. Studies evaluating compression in the treatment of ankle sprains were included. Two authors independently reviewed potential studies according to a set eligibility criteria. RESULTS: Twelve studies including 1,701 patients with ankle sprains were identified (level of evidence: four grade 1b; five grade 2b; three grade 4). Intermittent pneumatic compression (IPC), elastic tubular bandage and compression bandaging were all evaluated. Five of the 12 studies reported that compression therapy improves recovery after ankle injury, of which one evaluated IPC, and the remaining four elastic bandages (Elastoplast, class II elastic stockings, wool and crepe, focal compression with air stirrup). Five studies evaluating Tubigrip in ankle sprains concluded that Tubigrip has no positive effect on functional recovery and may increase the requirement for analgesia compared with no intervention. CONCLUSION: Compression may be an effective tool in the management of ankle injuries and has been shown to reduce swelling and improve quality of life in single studies. Definitive conclusions are hampered by the poor quality of evidence and the variety of treatments used. The most effective form of compression to treat ankle sprains or is yet to be determined. Adequately designed randomized control trials are clearly needed.