Intrinsic structural dynamics dictate enzymatic activity and inhibition.

Enzymes are known to sample various conformations, many of which are critical for their biological function. However, structural characterizations of enzymes predominantly focus on the most populated conformation. As a result, single-point mutations often produce structures that are similar or essentially identical to those of the wild-type enzyme despite large changes in enzymatic activity. Here, we show for mutants of a histone deacetylase enzyme (HDAC8) that reduced enzymatic activities, reduced inhibitor affinities, and reduced residence times are all captured by the rate constants between intrinsically sampled conformations that, in turn, can be obtained independently by solution NMR spectroscopy. Thus, for the HDAC8 enzyme, the dynamic sampling of conformations dictates both enzymatic activity and inhibitor potency. Our analysis also dissects the functional role of the conformations sampled, where specific conformations distinct from those in available structures are responsible for substrate and inhibitor binding, catalysis, and product dissociation. Precise structures alone often do not adequately explain the effect of missense mutations on enzymatic activity and drug potency. Our findings not only assign functional roles to several conformational states of HDAC8 but they also underscore the paramount role of dynamics, which will have general implications for characterizing missense mutations and designing inhibitors.

Picosecond Dynamics of a Small Molecule in Its Bound State with an Intrinsically Disordered Protein.

Intrinsically disordered proteins (IDPs) are highly dynamic biomolecules that rapidly interconvert among many structural conformations. These dynamic biomolecules are involved in cancers, neurodegeneration, cardiovascular illnesses, and viral infections. Despite their enormous therapeutic potential, IDPs have generally been considered undruggable because of their lack of classical long-lived binding pockets for small molecules. Currently, only a few instances are known where small molecules have been observed to interact with IDPs, and this situation is further exacerbated by the limited sensitivity of experimental techniques to detect such binding events. Here, using experimental nuclear magnetic resonance (NMR) spectroscopy 19F transverse spin-relaxation measurements, we discovered that a small molecule, 5-fluoroindole, interacts with the disordered domains of non-structural protein 5A from hepatitis C virus with a Kd of 260 ± 110 µM. Our analysis also allowed us to determine the rotational correlation times (τc) for the free and bound states of 5-fluoroindole. In the free state, we observed a rotational correlation time of 27.0 ± 1.3 ps, whereas in the bound state, τc only increased to 46 ± 10 ps. Our findings imply that it is possible for small molecules to engage with IDPs in exceptionally dynamic ways, in sharp contrast to the rigid binding modes typically exhibited when small molecules bind to well-defined binding pockets within structured proteins.

Gallbladder perforation: Diagnostic accuracy of new CT difficulty score in predicting complicated laparoscopic cholecystectomy.

PURPOSE: To formulate and evaluate the diagnostic performance and utility of a new CT difficulty score in predicting difficult laparoscopic surgery in cases of gallbladder (GB) perforation. METHODS: This prospective single centre study included a total of 48 diagnosed cases of GB perforation on CT between December 2021 and June 2023, out of which 24 patients were operated. A new 6-point CT difficulty scoring system was devised to predict difficult laparoscopic approach, based on patterns of inflammation around the perforated GB that were found to be surgically relevant. The pre-operative imaging findings on CT were studied in detail and correlation coefficients of various imaging findings were calculated to predict difficult surgery. RESULTS: On CECT, the type of perforation, according to the revised Niemeier's classification could be exactly delineated in all 48 patients. A CT difficulty score of ≥ 3 was found to a good predictor difficult laparoscopic approach, with statistical significance (p = 0.001), sensitivity of 94.44%, specificity of 83.33%, PPV of 94.44% and NPV of 83.33%. Inflammatory changes around duodenum showed maximum correlation coefficient of 0.744 (p = 0.0001), around colon showed a correlation coefficient of 0.657 (p = 0.0005), and in the omentum had a correlation coefficient of 0.5 (p = 0.013)). Inter-observer agreement was also calculated for various findings and it was found to have moderate to strong agreement (κ value 0.5-1.0). CONCLUSION: The CT difficulty scoring system can be an effective tool in predicting difficult laparoscopic surgery in cases of GB perforation in an emergency setting which can help in decision making and improved patient outcome.

Diagnosis of Covid-19 from CT slices using Whale Optimization Algorithm, Support Vector Machine and Multi-Layer Perceptron.

BACKGROUND: The coronavirus disease 2019 is a serious and highly contagious disease caused by infection with a newly discovered virus, named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). OBJECTIVE: A Computer Aided Diagnosis (CAD) system to assist physicians to diagnose Covid-19 from chest Computed Tomography (CT) slices is modelled and experimented. METHODS: The lung tissues are segmented using Otsu's thresholding method. The Covid-19 lesions have been annotated as the Regions of Interest (ROIs), which is followed by texture and shape extraction. The obtained features are stored as feature vectors and split into 80:20 train and test sets. To choose the optimal features, Whale Optimization Algorithm (WOA) with Support Vector Machine (SVM) classifier's accuracy is employed. A Multi-Layer Perceptron (MLP) classifier is trained to perform classification with the selected features. RESULTS: Comparative experimentations of the proposed system with existing eight benchmark Machine Learning classifiers using real-time dataset demonstrates that the proposed system with 88.94% accuracy outperforms the benchmark classifier's results. Statistical analysis namely, Friedman test, Mann Whitney U test and Kendall's Rank Correlation Coefficient Test has been performed which indicates that the proposed method has a significant impact on the novel dataset considered. CONCLUSION: The MLP classifier's accuracy without feature selection yielded 80.40%, whereas with feature selection using WOA, it yielded 88.94%.

Strengthening the Diagnosis of Drug-Resistant Tuberculosis Using NGS-Based Approaches and Bioinformatics Pipelines for Data Analysis in India.

In India, drug-resistant tuberculosis (DR-TB) is a major public health issue and a significant challenge to stop TB program. An estimated 27% of new TB cases and 44% of previously treated TB cases are resistant to at least one anti-TB drug. The conventional methods for DR-TB diagnosis are time-consuming and have limitations, leading to delays in treatment initiation and the spread of the disease. Next-generation sequencing (NGS) based approaches have emerged as a promising tool for diagnosing DR-TB, simultaneously offering rapid and accurate detection of resistance mutations in multiple genes. NGS-based approaches generate a large amount of data, which requires efficient and reliable bioinformatics pipelines for data analysis. TBProfiler and Mykrobe are the bioinformatics pipelines that have been created to analyze NGS data for the diagnosis of DR-TB. These pipelines use reference-based and machine-learning approaches to detect resistance mutations and predict drug susceptibility, enabling clinicians to make informed treatment decisions. Implementing NGS-based approaches and bioinformatics pipelines for DR-TB diagnosis can potentially improve patient outcomes by facilitating early detection of drug resistance and guiding personalized treatment regimens. However, the widespread adoption of these approaches in India faces several challenges, including high costs, limited infrastructure, and a lack of trained personnel. Addressing these challenges requires concerted effort to ensure equitable access to and effective implementation of these innovative technologies.

Short-term outcomes of enhanced recovery after surgery protocol in minimally invasive oesophagectomy: A prospective study.

BACKGROUND: Although fast-track treatment pathways are well established in colorectal surgeries, their role in oesophageal resections has not been well studied. This study aims to prospectively evaluate the short-term outcomes of enhanced recovery after surgery (ERAS) protocol in patients undergoing minimally invasive oesophagectomy (MIE) for oesophageal malignancy. PATIENTS AND METHODS: We studied a prospective cohort of 46 consecutive patients from January 2019 to June 2022 who underwent MIE for oesophageal malignancy. The ERAS protocol mainly consists of pre-operative counselling, pre-operative carbohydrate loading, multimodal analgesia, early mobilisation, enteral nutrition and initiation oral feed. Principal outcome measures were the length of post-operative hospital stay, complication rate, mortality rate and 30-day readmission rate. RESULTS: The median (interquartile range [IQR]) age of patients was 49.5 (42, 62) years, and 52.2% were female. The median (IQR) post-operative day of intercoastal drain removal and initiation of oral feed was 4 (3, 4) and 4 (4, 6) days, respectively. The median (IQR) length of hospital stay was 6 (6.0, 7.25) days, with a 30-day readmission rate of 6.5%. The overall complication rate was 45.6%, with a major complication (Clavien-Dindo ≥3) rate of 10.9%. Compliance with the ERAS protocol was 86.9%, and the incidence of major complications was associated with failure to follow the protocol ( P = 0.000). CONCLUSIONS: ERAS protocol in minimally invasive oesophagectomy is feasible and safe. This may result in early recovery with shortened length of hospital stay without an increase in complication and readmission rates.

Fortification by design: A rational approach to designing vitamin D delivery systems for foods and beverages.

Over the past few decades, vitamin D deficiency has been recognized as a serious global public health challenge. The World Health Organization has recommended fortification of foods with vitamin D, but this is often challenging because of its low water solubility, poor chemical stability, and low bioavailability. Studies have shown that these challenges can be overcome by encapsulating vitamin D within well-designed delivery systems containing nanoscale or microscale particles. The characteristics of these particles, such as their composition, size, structure, interfacial properties, and charge, can be controlled to attain desired functionality for specific applications. Recently, there has been great interest in the design, production, and application of vitamin-D loaded delivery systems. Many of the delivery systems reported in the literature are unsuitable for widespread application due to the complexity and high costs of the processing operations required to fabricate them, or because they are incompatible with food matrices. In this article, the concept of "fortification by design" is introduced, which involves a systematic approach to the design, production, and testing of colloidal delivery systems for the encapsulation and fortification of oil-soluble vitamins, using vitamin D as a model. Initially, the challenges associated with the incorporation of vitamin D into foods and beverages are reviewed. The fortification by design concept is then described, which involves several steps: (i) selection of appropriate vitamin D form; (ii) selection of appropriate food matrix; (iii) identification of appropriate delivery system; (iv) identification of appropriate production method; (vii) establishment of appropriate testing procedures; and (viii) system optimization.

Left hepatectomy for hepatic hydatid cyst with intra-biliary rupture: Better to be radical.

Echinococcal liver cysts are predominantly located in the right lobe of the liver and are mostly asymptomatic. A frank intra-biliary rupture (IBR) of hydatid cyst is uncommon, having variable clinical presentation and treatment options. We present a case of a 60-year-old male patient who presented with pain in the upper abdomen associated with vomiting but without jaundice. On investigations, he was diagnosed to have a left lobe hepatic hydatid cyst (HHC) with IBR for which left hepatectomy with bile duct exploration was performed. It highlights the benign nature of the disease for which seldom major hepatectomies have to be performed.

Jejunal mucinous adenocarcinoma: Unusual presentation of a rare pathology.

Mucinous adenocarcinoma of jejunum is a rare tumor of the gastrointestinal tract. Patients usually present after fifth decade of their life with non-specific symptoms. Delayed diagnosis is commonplace and often the reason for advanced disease and poor prognosis. These tumors may masquerade as other common malignancies, with a conclusive diagnosis only after the final histopathological examination. We present a case of jejunal mucinous adenocarcinoma, disguised as cecal malignancy, in an old female patient, managed with radical resection and adjuvant chemotherapy. The report reiterates that the mucinous variant of jejunal adenocarcinoma is a rare pathology with an unusual advanced presentation.

Total robotic choledochal cyst excision with Roux-en-Y hepaticojejunostomy in adults.

INTRODUCTION: Choledochal cyst (CDC) excision with bilio-enteric anastomosis has been reported by a laparoscopic approach. With the advent of robotic surgery, it is likely to simplify the performance of such complex procedures. Herein, we present our technique of total robotic CDC excision with intra-corporeal Roux-en-Y hepaticojejunostomy (RYHJ). METHODS: The patient was placed in a reverse Trendelenburg position. The robotic ports were placed in a "C"-shaped manner, with the camera port placed ~2 cm below the umbilicus. A 12-mm assistant port was placed in between the camera and the left-sided robotic port. Robotic dissection and excision of extrahepatic part CDC were performed, and subsequently, intra-corporeal robotic RYHJ with jejunojejunostomy was completed. Intra-operatively, indocyanine green dye was used to delineate the biliary anatomy and to check the anastomotic integrity. RESULTS: All three patients were female with a median age of 21 (18-34) years. Two patients had type IVa, and one had a mixed variant of type I(C) with type VI. The median operative time was 420 min, whereas docking and console time was 22 (20-25) min and 400 (360-450) min, respectively. The median blood loss and length of hospital stay were 50 (50-100) ml and 6 (5-6) days, respectively. One patient has mild acute pancreatitis in the post-operative period, which was managed conservatively. CONCLUSION: Robotic CDC excision and reconstruction seem to be a safe, feasible, and effective surgical option that provides the benefits of minimal access surgery but also greatly aids in complex dissection and reconstruction.

Total robotic lateral pancreaticojejunostomy and modified Frey's procedure for chronic calcific pancreatitis.

BACKGROUND: Surgical intervention has been shown to have good post-operative outcomes in patients with chronic pancreatitis with pain refractory to oral analgesics. We present our initial experience with robotic lateral pancreaticojejunostomy (LPJ) and modified Frey's procedure (MFP). METHODOLOGY: Patients with chronic calcific pancreatitis were evaluated with routine biochemical and radiological investigations. The indication of surgery was intractable pain which was recorded by an Intensity Frequency, Consequence (IFC) pain score. The patient was placed in a reverse Trendelenburg position with four 8-mm robotic ports and one 12-mm assistant port. Robotic ultrasound was utilized to identify the pancreatic duct. After retrieving all the calculi, which was confirmed by pancreatoscopy with the help of a video choledochoscope and performing the head coring in particular cases, the Roux-en-Y LPJ was performed. RESULTS: Among five patients (4 males, one female), robotic LPJ was performed in 2 and MFP in 3 patients. The cohort's median age was 32 (interquartile range (IQR), 28, 40) years, and the median (IQR) pancreatic duct size was 9 (9, 13) mm. The median (IQR) duration of the procedure was 385 (380, 405) minutes, with a median (IQR) blood loss of 100 (50-100) ml, and the patients were discharged on median post-operative day 5. The patients continue to do well at a median follow-up of 3-30 months without the requirement of oral analgesics. CONCLUSION: Robotic LPJ and MFP are feasible in experienced hands with good post-operative outcomes and enhanced quality of life. Intra-operative pancreatoscopy with the help of a choledochoscope can be utilized to ascertain the complete clearance of pancreatic duct stones and the consequent pain relief.

Factors affecting the fate of ß-carotene in the human gastrointestinal tract: A narrative review.

Carotenoids and their metabolites play crucial roles in human health such as in immunity, cell differentiation, embryonic development, maintenance of plasma membrane integrity, and gastrointestinal functions, in addition to counteracting night blindness and other eye-related diseases. However, carotenoid bioavailability is highly variable and often low. The bioavailability of ß-carotene, among the most frequently consumed carotenoid from the diet, is determined by food matrix related factors such as carotenoid dose, its location in food the matrix, the physical state in food, the presence of other food compounds in the matrix such as dietary fiber, dietary lipids, other micronutrients present such as minerals, and food processing, influencing also the size of food particles, and the presence of absorption inhibitors (fat replacers and anti-obesity drugs) or enhancers (nano-/micro-formulations). However, also host-related factors such as physiochemical interactions by gastrointestinal secretions (enzyme and salts) and other host-related factors such as surgery, age, disease, obesity, and genetic variations have shown to play a role. This review contributes to the knowledge regarding factors affecting the bioavailability of ß-carotene (food and host-relegated), as well as highlights in vitro models employed to evaluate ß-carotene bioavailability aspects.

Vitamin A fortification: Recent advances in encapsulation technologies.

Vitamin A is an essential micronutrient whose deficiency is still a major health concern in many regions of the world. It plays an essential role in human growth and development, immunity, and vision, but may also help prevent several other chronic diseases. The total amount of vitamin A in the human diet often falls below the recommended dietary allowance of approximately 900-1000 µ$ \umu $ g/day for a healthy adult. Moreover, a significant proportion of vitamin A may be degraded during food processing, storage, and distribution, thereby reducing its bioactivity. Finally, the vitamin A in some foods has a relatively low bioavailability, which further reduces its efficacy. The World Health Organization has recommended fortification of foods and beverages as a safe and cost-effective means of addressing vitamin A deficiency. However, there are several factors that must be overcome before effective fortified foods can be developed, including the low solubility, chemical stability, and bioavailability of this oil-soluble vitamin. Consequently, strategies are required to evenly disperse the vitamin throughout food matrices, to inhibit its chemical degradation, to avoid any adverse interactions with any other food components, to ensure the food is palatable, and to increase its bioavailability. In this review article, we discuss the chemical, physical, and nutritional attributes of vitamin A, its main dietary sources, the factors contributing to its current deficiency, and various strategies to address these deficiencies, including diet diversification, biofortification, and food fortification.

Evaluation of primary Ahmed Glaucoma valve implantation in post-traumatic angle recession glaucoma in Indian eyes.

PURPOSE: To highlight the efficacy of primary Ahmed glaucoma valve implantation in angle recession glaucoma following blunt ocular trauma in Indian eyes. DESIGN: A retrospective analytical study. MATERIALS AND METHODS: This study included 52 patients of angle recession glaucoma, who presented between Mar 2006 to Feb 2016, out of which 38 patients had undergone primary AGV implantation, while the rest were managed with topical anti-glaucoma medications. Preoperative data included age, sex, type and mode of injury, duration of injury, assessment of best-corrected visual acuity (BCVA) and intraocular pressure (IOP). The extent of angle recession was observed by gonioscopy. The intraocular pressure, visual acuity, and the number of anti-glaucoma medications were measured postoperatively. The success of this technique was analyzed by using a Kaplan-Meier cumulative survival curve. RESULTS: Following AGV implantation, the mean IOP was significantly reduced to 8.7 ± 2.2 at 1st day, 10.1 ± 2.2 at 7th day, 14.2 ± 3.4 at 3rd month, 15.6 ± 3.7 at 1 year, and 15.6 ± 3.6 at 3rd-year follow-up showing statistically significant values (p < 0.001) at each visit. The IOP was successfully controlled at the last follow-up without topical treatment. Mean BCVA at 3 years -post-AGV was 0.144 (0.151) (LogMAR) which was statistically significant (p < 0.001) as compared to the mean BCVA of 0.898 (± 0.205) LogMAR units at presentation. The success rate by Kaplan-Meier survival curve analysis was 90% at the mean follow-up duration of 29.47 ± 3.39 months. Overall surgical complications were noted in the form of prolonged hypotony, hyphema in 7 patients (13.5%). CONCLUSIONS: In medically uncontrolled post-traumatic angle recession glaucoma, primary AGV Implantation is a safe and effective surgical procedure with lesser complication rates providing long-term IOP control in a younger population.

Occupational exposure to pesticides in female tea garden workers and adverse birth outcomes.

Pesticides are globally used to eliminate pests from crops and plants. The increased use of pesticides has posed a serious threat to human health. This study evaluates the effects of pesticide exposure on pregnancy outcomes in tea garden workers (TGW). The acetylcholinesterase (AChE) activity was measured in the maternal blood, placenta, and cord blood of TGW and housewives (HWs). The placental structure and expression of hypoxia-inducible factor (HIF)-1α were also analyzed in TGW and HW groups delivering low birth weight (LBW) and normal birth weight (NBW) babies. A significantly decreased AChE activity was observed in maternal blood and cord blood in TGW as compared with HW in the LBW group. However, it did not change significantly in the NBW group (p < .05). The adjusted regression analysis of birth outcomes (birth weight, head circumference, infant's length, and ponderal index) revealed a significant and positive association with the levels of AChE activity in maternal blood, placenta, and cord blood in TGW (p < .05). The histological analysis showed significantly higher placental syncytial knots, chorangiosis, fibrinoid deposition, necrosis, and stromal fibrosis in the LBW group of TGW. Microinfarction, increased fibrinoid deposition, and atypical villi characteristics, such as mushroom-like structures, were observed during scanning electron microscopy along with increased HIF-1α expression in placental tissues of TGW exposed to pesticides. Results suggest that occupational pesticide exposure during pregnancy may decrease AChE activity and cause in utero pathological changes accompanied by an increased HIF-1α expression, which also contributes to placental insufficiency and fetal growth restriction.

Management of Obscurely Dilated Common Bile Duct with Normal Liver Function Tests: A Pragmatic Approach.

OBJECTIVE: Dilated common bile duct (CBD) (8-15 mm) with normal liver function tests is seen not infrequently, while management of such patients is ambiguous. We propose a treatment algorithm for this cohort of patients after observing them over a period of 8 years. METHODS: Seventy-eight such patients were managed from 2009 to 2017 and categorized as: Group A-dilated CBD with post-cholecystectomy status (n = 15); B-dilated CBD with cholelithiasis (n = 34); C-dilated CBD without cholelithiasis (n = 16); D-dilated CBD with no cause identified and underwent CBD excision (n = 13). Causes for CBD dilatation were evaluated. The outcome of patients in Group B + C without any cause (n = 33) was compared with Group D. RESULT: Median age, CBD diameter, bilirubin and alkaline phosphatase were 51 years (13-79), 10 mm (8-20), 0.6 mg/dl (0.2-2.5) and 126 IU (60-214), respectively. Group-A patients who did not manifest any cause of CBD dilatation were managed conservatively. The aetiology was identified in 17/50 patients in Group B & C [acute pancreatitis (n = 6), passed CBD calculi (n = 3), perivaterian diverticulum (n = 3), viral aetiology (n = 4) and tumour (n-1)]. In Group-C, 7 patients with no obvious cause underwent endoscopic sphincterotomy, pancreatoduodenectomy (n = 1), and the rest were managed conservatively (n = 8). There was no significant difference in the complication between Group B + C (without any cause) and Group D (3/33 vs. 1/13; p = 0.58) at a median follow-up of 72 months (30-90). CONCLUSION: Dilated CBD with normal LFT's without apparent cause is mostly benign and of no consequence. Excision of the CBD is not required for most of these patients.

Management options for post-esophagectomy chylothorax.

Chylothorax, although an uncommon complication of esophagectomy, is associated with high morbidity and mortality if not treated promptly. Consequently, knowledge of the thoracic duct (TD) anatomy is essential to prevent its inadvertent injury during surgery. If the TD is injured, early diagnosis and immediate intervention are of paramount importance; however, there is still no universal consensus about the management of post-operative chylothorax. With increasing advances in the spheres of interventional radiology and minimally invasive surgery, there are now several options for managing TD injury. We review this topic in detail to provide a comprehensive and practical overview to help surgeons manage this challenging complication. In particular, we discuss an appropriate step-up approach to prevent the morbidity associated with open surgery as well as the metabolic, nutritional, and immunological disorders that accompany a prolonged illness.

Turbulent Flow in a Cavernous Sinus Lesion: Does It Suggest Something?

A 14-year-old boy who had been complaining of double vision for the previous month was referred for neuro-ophthalmological evaluation. He was carrying a diagnosis of a cavernous sinus haemangioma causing a right VIth nerve palsy, based on imaging elsewhere. He reported having a boil at the angle of his mouth, which was associated with left-sided facial cellulitis, two weeks before the onset of the diplopia. His blood investigations showed a leukocytosis with elevated inflammatory markers. Re-evaluation of the magnetic resonance imaging suggested a sac-like out-pouching in the intracavernous part of the right internal carotid artery with differential intensity suggestive of turbulent flow. On the basis of the clinico-radiological findings, a diagnosis of mycotic aneurysm of the cavernous sinus part of internal carotid artery was made. A high index of suspicion is required to detect this rare clinical entity, which is associated with a potentially catastrophic clinical course.

Neurological consequences of COVID-19: what have we learned and where do we go from here?

The coronavirus disease-19 (COVID-19) pandemic is an unprecedented worldwide health crisis. COVID-19 is caused by SARS-CoV-2, a highly infectious pathogen that is genetically similar to SARS-CoV. Similar to other recent coronavirus outbreaks, including SARS and MERS, SARS-CoV-2 infected patients typically present with fever, dry cough, fatigue, and lower respiratory system dysfunction, including high rates of pneumonia and acute respiratory distress syndrome (ARDS); however, a rapidly accumulating set of clinical studies revealed atypical symptoms of COVID-19 that involve neurological signs, including headaches, anosmia, nausea, dysgeusia, damage to respiratory centers, and cerebral infarction. These unexpected findings may provide important clues regarding the pathological sequela of SARS-CoV-2 infection. Moreover, no efficacious therapies or vaccines are currently available, complicating the clinical management of COVID-19 patients and emphasizing the public health need for controlled, hypothesis-driven experimental studies to provide a framework for therapeutic development. In this mini-review, we summarize the current body of literature regarding the central nervous system (CNS) effects of SARS-CoV-2 and discuss several potential targets for therapeutic development to reduce neurological consequences in COVID-19 patients.

Intriguing electronic and optical prospects of FCC bimetallic two-dimensional heterostructures: epsilon near-zero behavior in UV-Vis range.

A higher superconducting critical temperature and large-area epsilon-near-zero systems are two long-standing goals of the scientific community, having an explicit relationship with the correlated electrons in localized orbitals. Motivated by the recent experimental findings of the strongly correlated phenomena in nanostructures of simple Drude metallic systems, we have theoretically investigated some potential bimetallic FCC combinations having close resemblance with the experimental systems. The explored systems include the large-area interface to the embedded and doped two-dimensional (2D) combinatorial nanostructures. Using different effective single-particle first-principles approaches encompassing density functional theory (DFT), time-dependent DFT (TDDFT), phonon and DFT-coupled quantum transport, we propose some interesting correlated prospects of potential bimetallic nanostructures like Au/Ag and Pt/Pd. For the 2D doped and embedded nanostructures of these systems, the DFT-calculated non-trivial band-structures indicate the interfacial morphology-induced band localization. The calculated Fermi-surface topology of the nanostructures and the corresponding nesting behavior may be emblematic to the presence of instabilities, such as charge density waves. The optical attributes extracted from the TDDFT calculations result in near-zero behavior of both real and imaginary parts of the dynamical dielectric response in the ultra-violet to visible (UV-Vis) optical range. In addition, low-energy intra-band plasmonic oscillations, as present for individual metallic surfaces, are completely suppressed for the embedded and doped nanostructures. The TDDFT-derived electron-energy loss spectra manifest the survival of only inter-band transitions. The presence of soft phonons and dynamic instabilities is observed from the phonon-dispersion of the nanostructured systems. Quantum transport calculations on the simplest possible device made out of these bimetallic systems reveal the generation of highly transmitting pockets over the cross-sectional area for some selected device geometry. We envisage that, if scrutinized experimentally, such systems may unveil many fascinating interdisciplinary aspects of orbital chemistry, physics and optics, promoting their relevant applications in many diverse fields.