Moiré superlattices in twisted two-dimensional halide perovskites.

Moiré superlattices have emerged as a new platform for studying strongly correlated quantum phenomena, but these systems have been largely limited to van der Waals layer two-dimensional materials. Here we introduce moiré superlattices leveraging ultrathin, ligand-free halide perovskites, facilitated by ionic interactions. Square moiré superlattices with varying periodic lengths are clearly visualized through high-resolution transmission electron microscopy. Twist-angle-dependent transient photoluminescence microscopy and electrical characterizations indicate the emergence of localized bright excitons and trapped charge carriers near a twist angle of ~10°. The localized excitons are accompanied by enhanced exciton emission, attributed to an increased oscillator strength by a theoretically predicted flat band. This research showcases the promise of two-dimensional perovskites as unique room-temperature moiré materials.

Interventions in cerebrovascular emergencies among patients with Paroxysmal nocturnal haemoglobinuria - A word of caution.

INTRODUCTION: Paroxysmal nocturnal haemoglobinuria (PNH) is a clonal hematopoietic disorder, where there is deficiency of glycosylphosphatidylinositol (GPI) anchored proteins in the cell membrane, leading to increased complement sensitivity of red blood cells, intravascular hemolysis and vascular inflammation. Arterial and venous strokes in patients with PNH are a rarity posing significant diagnostic and therapeutic challenges. We report our experience with management of PNH patients with cerebrovascular emergencies. METHODS: We report 2 patients with PNH, one who was previously diagnosed with PNH and had arterial stroke, the other had an index presentation of cerebral venous sinus thrombosis (CVT) and was subsequently diagnosed with PNH. We also present the systematic review of literature reporting similar cases, highlighting the challenges in management. RESULTS: Both patients presented to our centre with cerebrovascular emergency. The first patient was a diagnosed with PNH, and presented with left hemispheric infarction caused by thrombosis of middle cerebral artery. He was thrombolysed and underwent mechanical thrombectomy, which was unsuccessful in view of repeated re - thrombosis of the vessel. The patient survived with significant disability. The second patient had severe cerebral venous sinus thrombosis with large right hemispheric hemorrhagic venous infarction. She underwent emergency decompressive hemicraniectomy complicated by massive blood loss and disseminated intravascular coagulation. She subsequently had recurrent life threatening intracranial bleed secondary to platelet transfusions, thrombocytopenia, and use of contrast agents. She progressed to develop Budd Chiari syndrome and was initiated on Eculuzimab. She became transfusion independent, however remained in minimally conscious state and succumbed to sepsis. CONCLUSIONS: Management of arterial and venous strokes is complex in patients with PNH. Invasive procedures and platelet transfusions are to be avoided in acute thrombosis, till robust evidence is available establishing the safety of the same in patients with PNH. Eculuzimab is a promising option, but far from reach for patients in developing countries.

Pathophysiological basis in the management of myasthenia gravis: a mini review.

Myasthenia gravis is an autoimmune disorder characterized by the presence of autoantibodies against the acetylcholine receptor present in the post-synaptic membrane of the neuromuscular junction impairing the muscle contraction and causing the patient suffering from the disorder to develop a myriad of muscular defects ranging from drooping of eyelids, blurred or double vision, shortness of breath, difficulty in swallowing, as well as weakness of limbs and arms. Myasthenia gravis is known as the disease of old men and young women but in contrast to the global scenario, in India, myasthenia gravis was found to be predominant in males with the ratio of 2.70:1. Though the disorder has been studied for centuries, the true reason for disease and its pathophysiology still eludes us. But recent advancement in molecular biology and diagnostic tools has enabled us to identify many targets for pharmacotherapy as well as for early diagnosis. Thus, improving the patient's morbidity and quality of life. In this article, we are discussing the recent advancements made in diagnosis and therapy of the disease.

Effect of Two Different Ultrafast Curing Exposure Durations on the Surface Hardness of Bulk Fill Composite - An In-Vitro Study.

AIM: The aim of the present study is to assess the microhardness of resin-based composites (RBCs) cured with ultrafast curing mode at two different exposure durations. STUDY DESIGN: This is an experimental in-vitro study. Forty-five cylindrical composite specimens were prepared to a dimension of 5 mm height and 4 mm diameter. Curing was done using three different exposure modes and duration with dual mode LED curing light as follows: Group I: Ultrafast curing mode for 1 second at 2300 mW/cm2 (n = 15); Group II: Ultrafast curing mode for 3 second at 2300 mW/cm2 (n = 15) and Group III: Standard exposure mode for 20 second at 1000 mW/cm2 (n = 15). Vicker's microhardness measurement was done on both the curing and non-curing sides of the specimen using a motorised diamond-faced micro-indenter (Wilson Wolpwert, Germany) using a load of 50 gram and a dwell time of 30 second. STATISTICAL ANALYSIS: Kruskal Wallis ANOVA was used to test for difference between the three groups followed by Mann-Whitney U test for post-hoc analysis. RESULTS: The microhardness values of the composite cured with a conventional curing unit were significantly higher than the ultrafast cured specimens. CONCLUSION: Low-intensity conventional curing lights were found to perform better than the high-intensity ultrafast curing units.

Exciton annihilation in molecular aggregates suppressed through quantum interference.

Exciton-exciton annihilation (EEA), an important loss channel in optoelectronic devices and photosynthetic complexes, has conventionally been assumed to be an incoherent, diffusion-limited process. Here we challenge this assumption by experimentally demonstrating the ability to control EEA in molecular aggregates using the quantum phase relationships of excitons. We employed time-resolved photoluminescence microscopy to independently determine exciton diffusion constants and annihilation rates in two substituted perylene diimide aggregates featuring contrasting excitonic phase envelopes. Low-temperature EEA rates were found to differ by more than two orders of magnitude for the two compounds, despite comparable diffusion constants. Simulated rates based on a microscopic theory, in excellent agreement with experiments, rationalize this EEA behaviour based on quantum interference arising from the presence or absence of spatial phase oscillations of delocalized excitons. These results offer an approach for designing molecular materials using quantum interference where low annihilation can coexist with high exciton concentrations and mobilities.

Cri-Du-Chat Syndrome - A Rare Case Report.

The Cri-du-chat Syndrome (CdCs) is a rare genetic syndrome first described by Jerome Lejeune in 1963, characterized mainly by the high pitched cat like cry. The prevalence of CdCs was varied in between 1:15,000 to 1:50,000 in live birth and more common in female gender with a ratio of 4:3 [1, 2] .The condition may be accompanied by developmental and cognitive delays, poor spatial awareness, impaired ambulation, and poor sensori-motor skills. Other associated problems described include cardiovascular, renal, gastrointestinal, neurological abnormalities, preauricular tags, syndactyly, hypospadias, and cryptorchidism.1 Recent literatures show that autistic behaviours are common in various genetic disorders [3].Fatigue level of children with cri du chat syndrome was associated with the expression of autistic features [4]. Cri-du-chat syndrome is a rare genetic disorder resulting in various physical and psychological abnormalities due the deletion of chromosome 5P-. We encountered a case of cri-du-chat syndrome having external auditory canal atresia, hearing loss with speech delay. A multidisciplinary approach is required for diagnosis and management of such patients. Otological management is early identification of hearing loss and speech rehabilitation. Awareness about antenatal screening for congenital anomalies and genetic counselling is necessary among the general population.

Postnatal percentile growth charts for Indian appropriate for gestational age (AGA) very low birth weight babies.

AIMS: To develop postnatal percentile growth charts for Indian very low birth weight (VLBW) appropriate for gestational age (AGA) babies till 37 weeks post conceptional age (PCA). METHODS: Prospective, mixed longitudinal study in 105 VLBW AGA (male 73 and female 32) babies weighing <1500 g and <34 weeks gestation born over 1 year. All were weighed daily until discharge and then weekly till 37 weeks of PCA. The percentile weight curves were computed in four categories : ≤28 weeks, 29-30, 31-32 and 33 weeks, and a total of seven percentile distributions (3rd, 10th, 25th, 50th, 75th, 90th& 97th) were generated. Entire data were subjected to Tanner's 1951 method to compute mean and standard deviation for body weight. The arithmetic mean served the 50(th) percentile. RESULTS: All babies at birth were <50th centile as per Lubchenco's intrauterine growth chart. This pattern was more evident in higher gestation (31-32 and 33 weeks) than lower gestation (≤28 and 29-30 weeks). At 37 weeks PCA, all were <10th centile and the lowest was in ≤28 weeks gestation. CONCLUSIONS: Our babies are born smaller, and growth rate is slower than their western counterparts. Babies at lowest gestation had slowest postnatal growth. Hence, we need a separate growth chart for our babies.

Fibrovascular Polyp of the Cervical Esophagus: A Rare Neoplasm.

Fibrovascular polyps are rare benign epithelial neoplasia of the cervical esophagus. Usually they are large and frequently require a thoracotomy/thoracoscopy. This is a case report of an elderly lady with a large Fibrovascular polyp who had anemia and weight loss due to dysphagia, managed by rendezvous technique.

Cholesteatoma extending into the sternocleidomastoid muscle presenting as a Bezold abscess.

Cholesteatoma is a non-neoplastic cystic lesion arising in the middle ear cleft with the propensity to spread and recur after surgery, but it is unusual to find cholesteatoma invading sternocleidomastoid muscle after 15 years of modified radical mastoidectomy and presenting as Bezold abscess. In this report, the authors highlight the fact that cholesteatoma recurrence if neglected can present as a Bezold abscess with the invasion of cholesteatoma from the mastoid tip into the sternocleidomastoid muscle. This requires complete excision of the cholesteatoma sac along with the surrounding soft tissue.

Mucus targeting as a plausible approach to improve lung function in COVID-19 patients.

COVID-19 (SARS-CoV-2) has emerged as one of the worst pandemics that have tormented the globe due to its highly contagious nature. Even if the disease manifests fever-like symptoms mostly, the disease may progress to the pulmonary-hyper inflammatory phase, with severe pneumonia, hypoxia and subsequent multiple organ infection. This subsequently creates a huge burden to the health care systems across the globe for an immediate arrangement of ventilator facilities, oxygen supply and advanced health care. We evaluated the pathological similarity of COVID-19 with other airway obstructive disorders such as COPD and asthma and found typical mucus hypersecretion and mucus plugging in COVID-19 subjects. From several bronchoscopy and clinical autopsy carried out in COVID-19 patients, the overexpression of mucin gene was evident which play a significant role in mucus hypersecretion and accumulation, leading to airway obstruction and further to respiratory distress. In the present work, we highlight the need for intense research inputs to elucidate the exact role the mucus plays in worsening COVID-19 symptoms. This will further help to find a proper approach to quantify the airway mucus plugging in each patient and to develop an appropriate therapy either to inhibit mucus secretion or to improve mucus clearance through well-designed clinical trials.

Antibacterial activity and debonding force of different lingual retainers bonded with conventional composite and nanoparticle containing composite: An in vitro study.

BACKGROUND: To evaluate the antibacterial activity and debonding force of retainers bonded with conventional and nanoparticle (TiO2) containing composite. METHODOLOGY: Antibacterial activity was tested against Streptococcus mutans and Lactobacillus acidophilus using disk agar diffusion, biofilm inhibition, and eluted components tests. For the eluted components test, colony counts of bacteria were tested on 0, 3, and 30 days. Three different retainers were bonded to the lingual surface of extracted lower incisors using conventional and 1% TiO2 composite. Samples were divided as follows: Group 1: 1a, stainless steel retainer (Bond-a-Braid) with conventional composite, and 1b, stainless steel retainer with nanoparticle composite; Group 2: 2a, titanium retainer with conventional composite, and 2b, titanium retainer with nanoparticle composite; Group 3: 3a, fiber-reinforced retainer (Interlig) with conventional composite, and 3b, fiber-reinforced retainer with nanoparticle composite. The Instron stereomicroscope was used to test debonding force and failure sites respectively. RESULTS: In the disk agar diffusion test, TiO2 composite has shown more inhibition zones. Biofilm inhibition test showed a significant decrease in colony counts of both organisms in the TiO2 group. The eluted component test showed a significant decrease in colony counts from day 0 to day 30 in the TiO2 group compared with the control group. The highest debonding force was observed in stainless steel retainers with conventional composite, and lowest in fiber-reinforced composite retainers with TiO2 composite, with no significant difference in Adhesive Remnant Index scores. CONCLUSION: The TiO2 composite group showed greater antibacterial activity without compromising the bond strength, which was statistically significant. Compared with other groups, stainless steel wires bonded with conventional composite showed the highest debonding force.

Culture and characterization of human dental pulp­derived stem cells as limbal stem cells for corneal damage repair.

Limbal stem cell deficiency (LSCD) is one of the leading causes of corneal damage. Injury or inflammation in the cornea causes LSCD, which may be unilateral or bilateral depending upon the cause. Limbal epithelial cell implants successfully improve vision in patients with chemical injury­induced LSCD. Transplantation of cultured epithelial stem cells has become a treatment of choice for numerous patients with LSCD. Bilateral LSCD is frequently observed in the general population, where no residual stem cells are available for ex vivo culture. Allografts are associated with a high risk of rejection, neoplasia, and disease transmission. In this respect, allogenic cell populations from other regions in the patient may substitute for allogenic material. In the present study, dental pulp stem cells were cultured in limbal stem cell media and these cells were characterized against limbal stem cells, revealing the significance of using dental pulp stem cell treatment in bilateral LSCD. The morphology and culture pattern of both limbal and dental pulp stem cells grown in limbal stem­specific media were similar. Polymerase chain reaction analysis revealed that stem cell markers were highly expressed in limbal stem cells compared to in dental pulp stem cells, regardless of the medium and scaffold in which they were grown. Although dental pulp stem cell molecular expression is quite low at the transcript level, the functional protein level according to immunocytochemistry and western blot analyses demonstrated that stem cells and corneal differentiation molecule levels were quite high, indicating their potential as limbal stem cells in the respective microenvironment.