One-Pot Colloidal Synthesis Enables Highly Tunable InSb Short-Wave Infrared Quantum Dots Exhibiting Carrier Multiplication.

Colloidal quantum dots (CQDs) are emerging materials for short-wave infrared (SWIR, ≈1100-3000 nm) photodetectors, which are technologically important for a broad array of applications. Unfortunately, the most developed SWIR CQD systems are Pb and Hg chalcogenides; their toxicity and regulated compositions limit their applications. InSb CQD system is a potential environmentally friendly alternative, whose bandgap in theory, is tunable via quantum confinement across the SWIR spectrum. However, InSb CQDs are difficult to exploit, due to their complex syntheses and uncommon reactive precursors, which greatly hinder their application and study. Here, a one-pot synthesis strategy is reported using commercially available precursors to synthesize-under standard colloidal synthesis conditions-high-quality, size-tunable InSb CQDs. With this strategy, the large Bohr exciton radius of InSb can be exploited for tuning the bandgap of the CQDs over a wide range of wavelengths (≈1250-1860 nm) across the SWIR region. Furthermore, by changing the surface ligands of the CQDs from oleic acid (OA) to 1-dodecanthiol (DDT), a ≈20-fold lengthening in the excited-state lifetime, efficient carrier multiplication, and slower carrier annihilation are observed. The work opens a wide range of SWIR applications to a promising class of Pb- and Hg-free CQDs.

Introducing Intermolecular Cation-π Interactions for Water-Stable Low Dimensional Hybrid Lead Halide Perovskites.

Optoelectronically active hybrid lead halide perovskites dissociate in water. To prevent this dissociation, here, we introduce long-range intermolecular cation-π interactions between A-site cations of hybrid perovskites. An aromatic diamine like 4,4'-trimethylenedipyridine, if protonated, can show a long-range cation-π stacking, and therefore, serves as our A-site cation. Consequently, 4,4'-trimethylenedipyridinium lead bromide [(4,4'-TMDP)Pb2 Br6 ], a one-dimensional hybrid perovskite, remains completely stable after continuous water treatment for six months. Mechanistic insights about the cation-π interactions are obtained by single-crystal X-ray diffraction and nuclear magnetic resonance spectroscopy. The concept of long-range cation-π interaction is further extended to another A-site cation 4,4'-ethylenedipyridinium ion (4,4'-EDP), forming water-stable (4,4'-EDP)Pb2 Br6 perovskite. These water-stable perovskites are then used to fabricate white light-emitting diode and for light up-conversion through tunable third-harmonic generation. Note that the achieved water stability is the intrinsic stability of perovskite composition, unlike the prior approach of encapsulating the unstable perovskite material (or device) by water-resistant materials. The introduced cation-π interactions can be a breakthrough strategy in designing many more compositions of water-stable low-dimensional hybrid perovskites.

Bi3+ -Er3+ and Bi3+ -Yb3+ Codoped Cs2 AgInCl6 Double Perovskite Near-Infrared Emitters.

Bi3+ and lanthanide ions have been codoped in metal oxides as optical sensitizers and emitters. But such codoping is not known in typical semiconductors such as Si, GaAs, and CdSe. Metal halide perovskite with coordination number 6 provides an opportunity to codope Bi3+ and lanthanide ions. Codoping of Bi3+ and Ln3+ (Ln=Er and Yb) in Cs2 AgInCl6 double perovskite is presented. Bi3+ -Er3+ codoped Cs2 AgInCl6 shows Er3+ f-electron emission at 1540 nm (suitable for low-loss optical communication). Bi3+ codoping decreases the excitation (absorption) energy, such that the samples can be excited with ca. 370 nm light. At that excitation, Bi3+ -Er3+ codoped Cs2 AgInCl6 shows ca. 45 times higher emission intensity compared to the Er3+ doped Cs2 AgInCl6 . Similar results are also observed in Bi3+ -Yb3+ codoped sample emitting at 994 nm. A combination of temperature-dependent (5.7 K to 423 K) photoluminescence and calculations is used to understand the optical sensitization and emission processes.

Molecular Intercalation and Electronic Two Dimensionality in Layered Hybrid Perovskites.

In layered hybrid perovskites, such as (BA)2 PbI4 (BA=C4 H9 NH3 ), electrons and holes are considered to be confined in atomically thin two dimensional (2D) Pb-I inorganic layers. These inorganic layers are electronically isolated from each other in the third dimension by the insulating organic layers. Herein we report our experimental findings that suggest the presence of electronic interaction between the inorganic layers in some parts of the single crystals. The extent of this interaction is reversibly tuned by intercalation of organic and inorganic molecules in the layered perovskite single crystals. Consequently, optical absorption and emission properties switch reversibly with intercalation. Furthermore, increasing the distance between inorganic layers by increasing the length of the organic spacer cations systematically decreases these electronic interactions. This finding that the parts of the layered hybrid perovskites are not strictly electronically 2D is critical for understanding the electronic, optical, and optoelectronic properties of these technologically important materials.

Controlled Synthesis of Terbium-Doped Colloidal Gd2O2S Nanoplatelets Enables High-Performance X-ray Scintillators.

Terbium-doped gadolinium oxysulfide (Gd2O2S:Tb3+), commonly referred to as Gadox, is a widely used scintillator material due to its exceptional X-ray attenuation efficiency and high light yield. However, Gadox-based scintillators suffer from low X-ray spatial resolution due to their large particle size, which causes significant light scattering. To address this limitation, we report the synthesis of terbium-doped colloidal Gadox nanoplatelets (NPLs) with near-unity photoluminescence quantum yield (PLQY) and high radioluminescence light yield (LY). In particular, our investigation reveals a strong correlation between PLQY, LY, particle size, and Tb3+concentration. Our synthetic approach allows precise control over the lateral size and thickness of the Gadox NPLs, resulting in a LY of 50,000 photons/MeV. Flexible scintillating screens fabricated with the solution-processable Gadox NPLs exhibited a 20 lp/mm X-ray spatial resolution, surpassing commercial Gadox scintillators. These high-performance and flexible Gadox NPL-based scintillators enable enhanced X-ray imaging capabilities in medicine and security. Our work provides a framework for designing nanomaterial scintillators with superior spatial resolution and efficiency through precise control of dimensions and dopant concentration.

Combining π-Conjugation and Cation-π Interaction for Water-Stable and Photoconductive One-Dimensional Hybrid Lead Bromide.

Hybrid lead halide perovskites and their derivatives are important optoelectronic materials but suffer from water instability. Combining both the optoelectronics and the water stability of such systems is a major challenge in material design today. To address this issue, we employ the well-known π-conjugation and cation-π interaction concepts in designing a hybrid lead halide perovskite derivative system. (4,4'-VDP)Pb2Br6 (VDP = vinylenedipyridinium) single crystals are prepared. They have a one-dimensional (1D) arrangement of inorganic Pb-Br sublattices connected via the 4,4'-VDP organic sublattice. The π-conjugation in the 4,4'-VDP sublattice allows electronic communication between the 1D Pb-Br units, reducing the band gap and improving the photoconductivity. Importantly, N+ of one 4,4'-VDP molecular ion interacts with the π-electron cloud of the adjacent one. This intermolecular cation-π interaction extends throughout the organic sublattice, making the hybrid crystal stable when stored under water for more than a year without requiring any encapsulations.

Comparative assessment of SARS CoV2-associated mortalities in 3 COVID waves and related risk factors: The South Kashmir's experience.

Introduction: Severe acute respiratory syndrome coronavirus 2 causing coronavirus disease 2019 (COVID-19) pandemic have spurted in three major waves in India at different times and had different levels of severity in different waves. The objective of our study was to determine the comparative mortality rate in three COVID-19 waves and determine the factors associated with mortality. Methods: We identified a cohort of 1,132 COVID-19 patients who were admitted between April 14, 2020 and February 08, 2022 at our center. All the admitted patients with positive COVID-polymerase chain reaction were included in the study. Sample characteristics were determined by screening age, sex, socio-economic status, occupation, symptomatology of COVID, patient status on admission, baseline investigations, comorbidities, medical history, oxygen dosage needed during admission, the span of hospital stay, diagnosis, and vitals such as blood pressure, pulse, and oxygen saturation. All the data were procured from an institutional database. Results: In total, 1,132 patients included in the study, the mean age was 65.08 ± 12.29 and 56% were males. The affliction rate was 42.13% in >60 years, 29.5% in 46-60 years, 20.8% in 31-45 years, and 7.4% in 30 years' group. In the first, second, and third waves of COVID-19, the mortality rates were 13.21%, 23.53%, and 11.39%, respectively. Among the comorbidities, mortality rates were proportionately higher in those with hypertension (6.7%), and diabetes (5.5%), than those with chronic obstructive pulmonary disease (3.3%), chronic kidney disease (CKD) (1.5%), heart disease (1.6%), and malignancy (0.2%). Conclusion: We identify the peaked mortalities in the second encounter which was predicted by age, comorbidities such as hypertension, and diabetes.

InAs Nanorod Colloidal Quantum Dots with Tunable Bandgaps Deep into the Short-Wave Infrared.

InAs colloidal quantum dots (CQDs) have emerged as candidate lead- and mercury-free solution-processed semiconductors for infrared technology due to their appropriate bulk bandgap, which can be tuned by quantum confinement, and promising charge-carrier transport properties. However, the lack of suitable arsenic precursors and readily accessible synthesis conditions have limited InAs CQDs to smaller sizes (<7 nm), with bandgaps largely restricted to <1400 nm in the near-infrared spectral window. Conventional InAs CQD synthesis requires highly reactive, hazardous arsenic precursors, which are commercially scarce, making the synthesis hard to control and study. Here, we present a controlled synthesis strategy (using only readily available and less reactive precursors) to overcome the practical wavelength limitation of InAs CQDs, achieving monodisperse InAs nanorod CQDs with bandgaps tunable from ∼1200 to ∼1800 nm, thus crossing deep into the short-wave infrared (SWIR) region. By controlling the reactivity through in situ precursor complexation, we isolate the reaction mechanism, producing InAs nanorod CQDs that display narrow excitonic features and efficient carrier multiplication. Our work enables InAs CQDs for a wider range of SWIR applications.

Effect of chirality on the optical properties of layered hybrid perovskite R- and S-α-methylbenzylammonium lead iodide.

The introduction of chirality in layered hybrid perovskites breaks the symmetry of their inorganic sub-lattices. Consequently, they show intriguing linear and non-linear optical properties. Here we explore the effect of chirality on the excitonic photoluminescence of chiral (R- and S-α-MBA)2PbI4 (MBA: methylbenzylammonium) at cryogenic temperatures. The induced chirality splits the excitonic emissions below 150 K. Additionally, (R- and S-α-MBA)2PbI4 show wavelength-tunable second harmonic generation (SHG) that depends strongly on the polarization angle of the incident light.

Oxidative Stress in Human Pathology and Aging: Molecular Mechanisms and Perspectives.

Reactive oxygen and nitrogen species (RONS) are generated through various endogenous and exogenous processes; however, they are neutralized by enzymatic and non-enzymatic antioxidants. An imbalance between the generation and neutralization of oxidants results in the progression to oxidative stress (OS), which in turn gives rise to various diseases, disorders and aging. The characteristics of aging include the progressive loss of function in tissues and organs. The theory of aging explains that age-related functional losses are due to accumulation of reactive oxygen species (ROS), their subsequent damages and tissue deformities. Moreover, the diseases and disorders caused by OS include cardiovascular diseases [CVDs], chronic obstructive pulmonary disease, chronic kidney disease, neurodegenerative diseases and cancer. OS, induced by ROS, is neutralized by different enzymatic and non-enzymatic antioxidants and prevents cells, tissues and organs from damage. However, prolonged OS decreases the content of antioxidant status of cells by reducing the activities of reductants and antioxidative enzymes and gives rise to different pathological conditions. Therefore, the aim of the present review is to discuss the mechanism of ROS-induced OS signaling and their age-associated complications mediated through their toxic manifestations in order to devise effective preventive and curative natural therapeutic remedies.

Temperature-Dependent Photoluminescence of Hexafluorobenzene-Intercalated Phenethylammonium Tin Iodide 2D Perovskite.

Tin halide perovskites are potential alternatives of lead halide perovskites. However, the easy oxidation of Sn2+ to Sn4+ brings in a challenge. Recently, layered two-dimensional hybrid tin halide perovskites have been shown to partially resist the oxidation process because of the presence of hydrophobic organic molecules. Consequently, such layered hybrid perovskites are being explored for optoelectronic applications. The optical properties of layered tin halide perovskites depend on the interlayer separation and the dielectric mismatch between the organic and inorganic layers. Intercalation (insertion) of a molecular species between the layers modifies the interlayer interactions affecting the optical properties of layered hybrid perovskites. We investigated the effect of hexafluorobenzene (HFB) intercalation in phenethylammonium tin iodide [(PEA)2 SnI4 ] using temperature-dependent (6 K to 300 K) photoluminescence (PL). HFB intercalation increases the bandgap. A strong PL quenching is observed in pristine (PEA)2 SnI4 below 150 K, probably because of the presence of non-emissive states. HFB intercalation suppresses the influence of such non-emissive states resulting in an increase in PL intensity at the cryogenic temperatures. Our results highlight that a simple molecular intercalation (non-covalent interaction) into layered hybrid perovskites can significantly tailor the electronic and optical properties.

Emergence of Aggregation Induced Emission (AIE), Room-Temperature Phosphorescence (RTP), and Multistimuli Response from a Single Organic Luminogen by Directed Structural Modification.

Multifunctional organic luminogens exhibiting simultaneous aggregation induced emission (AIE), room-temperature phosphorescence (RTP), and mechanochromism have recently attracted considerable attention owing to their potential applications in optoelectronics and bioimaging. However, a comprehensive correlation among these three distinguished properties is yet to be unveiled, which will help to decipher defined methodologies to design future generation multifunctional organic materials. Herein, we have demonstrated a route to obtain a multifunctional organic luminogen, starting from an ACQphore (TPANDI) by simple structural engineering. We have shown that a slight reduction in length of the planar acceptor moieties can effectively inhibit the undesirable π-π stacking interaction between molecules in the condensed state and thereby cause an ACQ to AIE type transformation from TPANDI to TPANMI and TPAPMI. Both TPANMI and TPAPMI exhibit RTP properties (even in ambient condition) because of the presence of a reasonably low singlet-triplet energy gap (ΔEST). In our study, these two luminogens were found to be mechano-inactive. Interestingly, an insertion of cyano-ethylene group and benzene linker in between the triphenylamine and phthalimide moieties introduced another luminogen TPACNPMI, which can simultaneously exhibit AIE, RTP, and mechanochromic properties.

Bloom syndrome in two siblings.

Bloom syndrome (congenital telangiectatic erythema) is a rare autosomal recessive disorder characterized by telangiectasias and photosensitivity, growth deficiency of prenatal onset, variable degrees of immunodeficiency, and increased susceptibility to neoplasms of many sites and types. We are reporting Bloom syndrome in two brothers from Kashmir (India), 8 and 6 years of age, who presented with erythematous rashes on the face, photosensitivity, and growth retardation.

Antigliadin antibodies in psoriasis.

BACKGROUND/OBJECTIVES: Although antigliadin antibodies (AGA) are markers of coeliac disease, elevated levels of these antibodies are also seen in many other autoimmune, neurological, haematological, collagen vascular and cutaneous disorders, even in the absence of clinically overt gastrointestinal disease. Several studies have reported an association between psoriasis and AGA, with improvement in severity of psoriasis on a gluten-free diet. This study aims to determine whether patients with psoriasis in Kashmir have an increased prevalence of elevated AGA. METHODS: A total of 120 patients (all native Kashmiris) with psoriasis and an equal number of age- and sex-matched controls without any personal or family history of autoimmune disorders were included in the study. Both groups were tested for IgA and IgG AGAs using a standard enzyme-linked immunosorbent assay method. RESULTS: No statistically significant difference in the prevalence of AGA among patients with psoriasis (6.67% for IgA and 4.17% for IgG) and control group individuals (7.5% IgA and 5.0% IgG) was observed. The mean AGA levels in the two groups were not statistically different. Furthermore, no significant association between AGA levels and psoriasis severity, joint involvement, age of onset of psoriasis or arthritis was observed. CONCLUSIONS: The results of our study show that AGA are not elevated in psoriasis patients as compared with a healthy population, and there is no association between AGA and psoriasis, its onset, severity and joint symptoms.

Parrilla urethra: A sequalae of electric shock torture to genitals in men. A 40 case series in Kashmir (India).

INTRODUCTION: Since the 20th century, electric shock torture has become one of the most prevalent methods of torture partly because it produces sequelae that are more challenging to visibly detect, particularly when administered using high voltage and low current. In sexual torture, a wire is wrapped around the head of the penis and a wire electrode is inserted into the urethra.This produces unbearable pain and can lead to urethral strictures with devastating physical and psychological consequences. OBJECTIVE: To document electric shock torture to genitals as an etiologic agent in urethral stricture and erectile dysfunction amongst survivors of electric torture introducing the term "parrilla urethra" for the electric shock torture urethral stricture. MATERIALS AND METHODS: The study included 40 patients who attended the Department of Urology, Directorate of Health services, Srinagar, Kashmir, India with obstructive lower urinary tract symptoms (LUTS) / obstructive uroflowmetry between March 2010 and November 2014. All cases had an antecedent of electric shock torture to genitals six months to one year prior to examination. Pre-post psychological impact and well-being was used through Global Assessment of Functioning (GAF) scores. RESULTS: The mean age of patients was 35.6 years. Most of the urethral strictures were located in the anterior urethra. Some degree of erectile dysfunction was present in all (100%) of patients. Psychological sequelae including depression, anxiety, acute stress disorder and symptoms of post-traumatic stress disorder were observed. Patients were treated with standard urethroplasty procedures after addressing the urethral stricture.This improved both physical and psychological sequelae of torture.

Ruptured heterotopic pregnancy: a rare cause for hemoperitoneum; report of three cases from kashmir, India.

Heterotopic pregnancy has been found in various forms but is still a rare event in the natural conception cycles, occurring in less than 1:30000 pregnancies with the incidence rising to 1:100 to 1:500 pregnancies duo to assisted reproductive technologies. Delay in diagnosing the condition can be fatal for both the mother and the fetus. Three patients aged 28, 31 and 26 years presented with amenorrhea of ten, eight and twelve weeks duration respectively with signs of peritonism and shock. Investigations revealed intra and extra uterine pregnancies in all the three cases with the rupture of the extra uterine pregnancies. All the cases were operated and first two cases were followed up postoperatively till the delivery of the term live babies. The third case is still under our follow up. A high index of suspicion by a general surgeon is needed in arriving at a prompt diagnosis of ruptured heterotopic pregnancy so that rapid resuscitation, heart sparing anesthesia and expeditious surgery is carried out for both maternal and intrauterine fetal wellbeing.

Encountering Meckel's diverticulum in emergency surgery for ascaridial intestinal obstruction.

BACKGROUND: Meckel's diverticulum is the most common congenital anomaly of the gastrointestinal tract. In children with intestinal ascariasis, the diverticulum remains asymptomatic or rarely the Ascaris lumbricoides may lead to its complications in the presence of massive intestinal roundworm load. Given that preoperative diagnosis is seldom carried out, when Meckel's diverticulum is found at laparotomy for obstructive intestinal complications of roundworm, the diverticulum should be removed as complications may occur at any time. The aim of this study was to describe the findings of concomitant presence of Meckel's diverticulum who had surgical intervention in symptomatic intestinal ascariasis in children. METHODS: A retrospective case review study of 14 children who had surgical intervention for symptomatic intestinal ascariasis having the presence of concomitant Meckel's diverticulum was done. The study was done at SMHS Hospital Srinagar, Kashmir. RESULTS: A total of the 14 children who had ascaridial intestinal obstruction with concomitant presence of Meckel's diverticulum were studied. Age of children ranged from 4-12 years, male:female ratio was 1.8:1. Nine patients had asymptomatic Meckel's diverticulum, whereas 5 patients with symptomatic signs were found in the course of emergency surgery for ascaridial intestinal obstruction. CONCLUSION: Meckel's diverticulum in intestinal ascariasis may pursue silent course or may be accompanied with complications of the diverticulitis, perforation or the gangrene. Incidental finding of the Meckel's diverticulum in the intestinal ascariasis should have removal.

Spectrum of abdominal organ injury in a primary blast type.

INTRODUCTION: Abdominal organ injury in a primary blast type is always challenging for diagnosis. Air containing abdominal viscera is most vulnerable to effects of primary blast injury. In any patient exposed to a primary blast wave who presents with an acute abdomen, an abdominal organ injury is to be kept in a clinical suspicion. AIM: Study various abdominal organ injuries occurring in a primary type of blast injury. MATERIAL AND METHODS: All those who had exploratory laparotomy for abdominal organ injuries after a primary blast injury for a period of 10 years from January 1998 - January 2008 were included in this retrospective study. RESULTS: Total 154 patients had laparotomy for abdominal organ injuries with a primary blast type of injury. Small intestine was damaged in 48 patients (31.1%) followed by spleen in 22.7% cases. 54 patients (35.06%) had more than one organ injured. Liver laceration was present in 30 patients (19.48%). Multiple small gut perforations were present in 37 patients (77.08%). Negative laparotomy was found in 5 patients (3.24%) whereas 3 (1.94%) had re-exploration. Mortality was present in 6 patients (3.89%). CONCLUSIONS: Primary blast injury causes varied abdominal organ injuries. Single or multiple organ damage can be there. Small intestine is commonest viscera injured. Laparotomy gives final diagnosis.

An unusual case of frost bite autoamputation of toes.

BACKGROUND: We report a case of a 15 year old young female who suffered autoamputation of left mid foot and four digits of right foot following repeated application of snow to relieve the pain in her frost bitten feet. CASE PRESENTATION: The sociodemographic background, cause, resulting injury and subsequent management are discussed. CONCLUSION: Such injuries are relatively rare but awareness of the risk of this type of injury is important.