MoS2 Field-Effect Transistor Performance Enhancement by Contact Doping and Defect Passivation via Fluorine Ions and Its Cyclic Field-Assisted Activation.

MoS2-based field-effect transistors (FETs) and, in general, transition metal dichalcogenide channels are fundamentally limited by high contact resistance (RC) and intrinsic defects, which results in low drive current and lower carrier mobilities, respectively. This work addresses these issues using a technique based on CF4 plasma treatment in the contacts and further cyclic field-assisted drift and activation of the fluorine ions (F-), which get introduced into the contact region during the CF4 plasma treatment. The F- ions are activated using cyclic pulses applied across the source-drain (S/D) contacts, which leads to their migration to the contact edges via the channel. Further, using ab initio molecular dynamics and density functional theory simulations, these F- ions are found to bond at sulfur (S) vacancies, resulting in their passivation and n-type doping in the channel and near the S/D contacts. An increase in doping results in the narrowing of the Schottky barrier width and a reduction in RC by ∼90%. Additionally, the passivation of S vacancies in the channel enhances the mobility of the FET by ∼150%. The CF4 plasma treatment in contacts and further cyclic field-assisted activation of F- ions resulted in an ON-current (ION) improvement by ∼90% and ∼480% for exfoliated and CVD-grown MoS2, respectively. Moreover, this improvement in ION has been achieved without any deterioration in the ION/IOFF, which was found to be >7-8 orders.

Neuroimaging and artificial intelligence for assessment of chronic painful temporomandibular disorders-a comprehensive review.

Chronic Painful Temporomandibular Disorders (TMD) are challenging to diagnose and manage due to their complexity and lack of understanding of brain mechanism. In the past few decades' neural mechanisms of pain regulation and perception have been clarified by neuroimaging research. Advances in the neuroimaging have bridged the gap between brain activity and the subjective experience of pain. Neuroimaging has also made strides toward separating the neural mechanisms underlying the chronic painful TMD. Recently, Artificial Intelligence (AI) is transforming various sectors by automating tasks that previously required humans' intelligence to complete. AI has started to contribute to the recognition, assessment, and understanding of painful TMD. The application of AI and neuroimaging in understanding the pathophysiology and diagnosis of chronic painful TMD are still in its early stages. The objective of the present review is to identify the contemporary neuroimaging approaches such as structural, functional, and molecular techniques that have been used to investigate the brain of chronic painful TMD individuals. Furthermore, this review guides practitioners on relevant aspects of AI and how AI and neuroimaging methods can revolutionize our understanding on the mechanisms of painful TMD and aid in both diagnosis and management to enhance patient outcomes.

Complications of Mandibular Distraction Osteogenesis in Infants with Isolated Robin Sequence.

Mandibular Distraction Osteogenesis (MDO) is now the preferred procedure to alleviate airway obstruction in infants with severe Robin Sequence (RS). However, there have been very few studies investigating complications related to MDO surgery performed on patients affected by isolated RS. In this study, age at distraction, weight at distraction, preoperative intubation, repeat MDO and complications associated with MDO were included as variables. Minor, moderate and major problems were evaluated and recorded as surgical site infections (SSI), injuries to the facial nerve, self-extinction hypertrophic scars, temporomandibular joint ankylosis, device failures, early ossification and fibrous non-union. One hundred and fifty one patients with isolated RS were included. At distraction, the mean age was 72 days (12-540 days) and the mean weight was 4.05 kg (2.4-12.2 kg). Only one patient needed tracheostomy after MDO, and none required further distraction. Ultimately, the complication rate was 15.23%, and there was a total of 7.95% minor, 9.27% moderate and 0% major complications. Minor incidents included surgical site infection (SSI) managed with antibiotics taken orally (n = 8), neuropraxia in the VII cranial nerve (CN) (n = 1), and hypertrophic scarring (n = 3). Incidents reported as moderate were SSIs managed with intravenous antibiotics (n = 9), incision and drainage (n = 3) and self-extubation (n = 2). There was no case of TMJ ankylosis. There were no cases of early or premature ossification, fibrous non-union and device fracture. In conclusion, MDO is an effective and appropriate management technique for infants with isolated RS and severe airway obstruction. Infections at the surgery site accounted for the vast majority of the complications. Further investigations may be needed to determine the long-term consequences of MDO.

Role of Chalcogen Defect Introducing Metal-Induced Gap States and Its Implications for Metal-TMDs' Interface Chemistry.

The contact resistance of the transition metal dichalcogenide (TMD) devices is not comparable to that of their silicon counterparts, probably due to a lack of clarity in their interface chemistry. Looking beyond the conventional Schottky-Mott rule, the metal chalcogen orbital overlaps, tunnel barrier, and metal-induced gap states (MIGSs) are crucial factors determining different metals' contact properties with TMDs. Exploring their properties helps TMDs' contact resistance engineering, driven mainly by their orbital overlaps and perturbing parameters. This work presents the interface chemistry of TMDs (MoS2, MoSe2, WS2, and WSe2) with different metals (Au, Cr, Ni, and Pd) in detail using density functional theory computations. Additionally, the work discusses the role of the chalcogen vacancy and interstitial defects in the metal-TMD interactions and corresponding MIGS features. The investigations reveal that Au does not show any significant MIGS due to its weak interactions with all the TMDs. However, other investigated metals have a strong affinity with TMDs, making significant MIGS contributions. All the metals offer n-type doping characteristics to TMDs due to valence charge transfer from the metals toward TMDs. The chalcogen vacancy boosts the orbital overlaps of the TMDs with all the metals. The vacancy reduces metal-TMD interfacial distance, which can be a promising technique to reduce the tunnel barrier and contact resistance. The MIGS and defect-induced gap states (DIGSs) reflect the possibility of Fermi-level pinning in the TMDs' contacts with Cr, Ni, and Pd. Besides, the work discloses that the chalcogen vacancy converts an n-type Pd-TMD interface into p-type due to reverse charge transfer after the vacancy. Chalcogen interstitial impurity also helps with contact resistance engineering for some metal-TMD systems by reducing the bond distance of the metal TMDs. Our study highlights the possibility of defect-assisted and MIGS-based contact engineering at the metal-TMD interfaces.

Yield of video electro encephalography for phase 1 pre-surgical evaluation of drug resistant epilepsy in 1200 adults: retrospective study from a tertiary center situated in a lower-middle-income country.

INTRODUCTION: Video Electroencephalography (VEEG) is crucial for presurgical evaluation of Drug Refractory Epilepsy (DRE). The yield of VEEG in large volume centers, particularly those situated in Low-and Middle-Income countries (LMIC) is not well studied. METHODOLOGY: We studied 1200 adults with drug resistant focal epilepsy whose seizures were recorded during VEEG in the epilepsy monitoring unit. VEEG review and analysis was done independently by trained epileptologists. Video EEG and MRI data were examined for concordance in order to generate a hypothesis for the presumed epileptogenic zone. RESULTS: Analysis of seizure semiology provided information on the symptomatogenic zone in most cases except for 33 (2.75%) patients. A total of 1050 (87.5%) patients showed interictal epileptiform discharges (IEDs) with most (58.3%) showing unilateral IEDs. Most patients (n = 1162, 96.83%) showed ictal EEG discharges of which 951(81.8%) had unilateral ictal onset. Abnormal MRI was seen in 978 (81.5%) patients. Concordance of electroclinical data obtained by analysis of VEEG with MRI abnormality could be established in most patients (63%). Concordance was higher for patients with ictal onset from temporal regions (83.71%) as compared to posterior cortex (55.4%) and frontal regions (43.5%.) CONCLUSION: This study highlights the high yield of VEEG in phase 1 presurgical evaluation in DRE. Systematic evaluation of data from VEEG provided lateralizing and localizing information in most cases. Concordance between VEEG and MRI findings was noted in most patients. These findings support steps to increase referral for pre-surgical evaluation in DRE.

A Review on Autophagy in Orofacial Neuropathic Pain.

Orofacial neuropathic pain indicates pain caused by a lesion or diseases of the somatosensory nervous system. It is challenging for the clinician to diagnose and manage orofacial neuropathic pain conditions due to the considerable variability between individual clinical presentations and a lack of understanding of the mechanisms underlying the etiology and pathogenesis. In the last few decades, researchers have developed diagnostic criteria, questionnaires, and clinical assessment methods for the diagnosis of orofacial neuropathic pain. Recently, researchers have observed the role of autophagy in neuronal dysfunction as well as in the modulation of neuropathic pain. On this basis, in the present review, we highlight the characteristics, classification, and clinical assessment of orofacial neuropathic pain. Additionally, we introduce autophagy and its potential role in the modulation of orofacial neuropathic pain, along with a brief overview of the pathogenesis, which in future may reveal new possible targets for treating this condition.

Breathing Mode's Temperature Coefficient Estimation and Interlayer Phonon Scattering Model of Few-Layer Phosphorene.

The breathing mode's Raman characteristic is a key parameter that estimates the number of layers and helps to determine interlayer thermal coupling in multilayer phosphorene. However, its temperature coefficient is not investigated yet, probably due to phosphorene's ambient instability, difficulties in capturing its Raman modes, and relatively weak temperature sensitivity than the corresponding primary intralayer Raman modes. Here, we captured the breathing modes' Raman scattering in multiple phosphorene flakes at different temperatures and estimated the corresponding first-order temperature coefficient. The captured modes show a negative temperature coefficient of around -0.0025 cm-1/K. Besides, we have explored a unique feature of the breathing mode phonon scattering with temperature. The modes closely follow the dominant three-phonon process and four-phonon process scattering phenomena at low- and high-temperature ranges. The three-phonon process scattering is dominant below ∼100 K, shifting to the dominant four-phonon process scattering beyond ∼150 K. Moreover, the phonon modes show anomalous behavior of blue shift with temperature during 100-150 K, probably due to transition in the scattering process. Our study shows the significant dependency of the breathing modes over temperature, which helps to understand and model phosphorene's interlayer thermal and mechanical properties. The study also reflects that phosphorene has significant interlayer heat transport capability due to three- and four-phonon scattering features.

First principles investigation of anionic redox in bisulfate lithium battery cathodes.

The search for an alternative high-voltage polyanionic cathode material for Li-ion batteries is vital to improve the energy densities beyond the state-of-the-art, where sulfate frameworks form an important class of high-voltage cathode materials due to the strong inductive effect of the S6+ ion. Here, we have investigated the mechanism of cationic and/or anionic redox in LixM(SO4)2 frameworks (M = Mn, Fe, Co, and Ni and 0 ≤ x ≤ 2) using density functional calculations. Specifically, we have used a combination of Hubbard U corrected strongly constrained and appropriately normed (SCAN+U) and generalized gradient approximation (GGA+U) functionals to explore the thermodynamic (polymorph stability), electrochemical (intercalation voltage), geometric (bond lengths), and electronic (band gaps, magnetic moments, charge populations, etc.) properties of the bisulfate frameworks considered. Importantly, we find that the anionic (cationic) redox process is dominant throughout delithiation in the Ni (Mn) bisulfate, as verified using our calculated projected density of states, bond lengths, and on-site magnetic moments. On the other hand, in Fe and Co bisulfates, cationic redox dominates the initial delithiation (1 ≤ x ≤ 2), while anionic redox dominates subsequent delithiation (0 ≤ x ≤ 2). In addition, evaluation of the crystal overlap Hamilton population reveals insignificant bonding between oxidized O atoms throughout the delithiation process in the Ni bisulfate, indicating robust battery performance that is resistant to irreversible oxygen evolution. Finally, we observe that both GGA+U and SCAN+U predictions are in qualitative agreement for the various properties predicted. Our work should open new avenues for exploring lattice oxygen redox in novel high voltage polyanionic cathodes, especially using the SCAN+U functional.

The Effect of Timing of Mandibular Distraction Osteogenesis on Weight Velocity in Infants Affected by Severe Robin Sequence.

Background: Impaired weight gain is prevalent in Robin Sequence (RS) newborns. Although mandibular distraction osteogenesis (MDO) has been proven to improve oral feeding, its impact on postoperative weight gain remains unclear. The purpose of this study is to explore whether MDO can help RS babies reach a normal weight, as well as the effect of MDO timing on weight velocity. Methods: One hundred infants with severe RS and one hundred with normal controls met the inclusion criteria for the study. Included patients underwent MDO. Weights at different timing points were recorded and analyzed and compared to normal controls. Results: After the distractor removal weights of patients undergoing MDO at <1 month and 1−2 months were close to the normal control (6.81 ± 0.93 kg versus 7.18 ± 0.61 kg, p = 0.012, and 6.82 ± 0.98 kg versus 7.37 ± 0.75 kg, p = 0.033, respectively), the weights of patients undergoing MDO at 2−3 months and 3−4 months still lagged behind (7.56 ± 1.29 kg versus 8.20 ± 0.61 kg, p = 0.000206 and 7.36 ± 1.05 kg versus 8.25 ± 0.77 kg, p = 0.004, respectively). The weights of all RS infants undergoing MDO showed no significant difference compared to the controls when they aged to 1 year (9.34 ± 0.99 kg versus 9.55 ± 0.45 kg, p = 0.254 for MDO at <1 month; 9.12 ± 0.91 kg versus 9.33 ± 0.46 kg, p = 0.100 for MDO at 1 to 2 months; 9.38 ± 0.29 kg versus 9.83 ± 0.53 kg, p = 0.098 for MDO at 2 to 3 months; and 9.38 ± 0.29 kg versus 9.83 ± 0.53 kg, p = 0.098 for MDO at 3 to 4 months). Conclusion: The MDO procedure helped patients with severe RS to reach a normal weight; and MDO intervention was recommended at an early stage for early weight gain.

First-Principles Molecular Dynamics Insight into the Atomic Level Degradation Pathway of Phosphorene.

Despite its remarkable properties, phosphorene is not promising for device application due to its instability or gradual degradation under ambient conditions. The issue still persists, and no technological solution is available to address this degradation due to a lack of clarity about degradation dynamics at the atomic level. Here, we discuss atomic level degradation dynamics of phosphorene under ambient conditions while investigating the involvement of degrading agents like oxygen and water using density functional theory and first-principles molecular dynamics computations. The study reveals that the oxygen molecule dissociates spontaneously over pristine phosphorene in an ambient environment, resulting in an exothermic reaction, which is boosted further by increasing the partial pressure and temperature. The surface reaction is mainly due to the lone pair electrons of phosphorous atoms, making the degradation directional and spontaneous under oxygen atoms. We also found that while the pristine phosphorene is hydrophobic, it becomes hydrophilic after surface oxidation. Furthermore, water molecules play a vital role in the degradation process by changing the reaction dynamics path of the phosphorene-oxygen interaction and reducing the activation energy and reaction energy due to its catalyzing action. In addition, our study reveals the role of phosphorous vacancies in the degradation, which we found to act as an epicenter for the observed oxidation. The oxygen attacks directly over the vacant site and reacts faster compared to its pristine counterpart. As a result, phosphorene edges resembling extended vacancy are prominent reaction sites that oxidize anisotropically due to different bond angle strains. Our study clears the ambiguities in the kinetics of phosphorene degradation, which will help engineer passivation techniques to make phosphorene devices stable in the ambient environment.

hsa-MiR-19a-3p and hsa-MiR-19b-3p Are Associated with Spinal Cord Injury-Induced Neuropathic Pain: Findings from a Genome-Wide MicroRNA Expression Profiling Screen.

Neuropathic pain in spinal cord injury (SCI) is associated with inflammation in both the peripheral and central nervous system (CNS), which may contribute to the initiation and maintenance of persistent pain. An understanding of factors contributing to neuroinflammation may lead to new therapeutic targets for neuropathic pain. Moreover, novel circulating biomarkers of neuropathic pain may facilitate earlier and more effective treatment. MicroRNAs (miRNAs) are short, non-coding single-stranded RNA that have emerged as important biomarkers and molecular mediators in physiological and pathological conditions. Using a genome-wide miRNA screening approach, we studied differential miRNA expression in plasma from 68 healthy, community-dwelling adults with and without SCI enrolled in ongoing clinical studies. We detected 2367 distinct miRNAs. Of these, 383 miRNAs were differentially expressed in acute SCI or chronic SCI versus no SCI and 71 were differentially expressed in chronic neuropathic pain versus no neuropathic pain. We selected homo sapiens (hsa)-miR-19a-3p and hsa-miR-19b-3p for additional analysis based on p-value, fold change, and their known role as regulators of neuropathic pain and neuroinflammation. Both hsa-miR-19a-3p and hsa-miR-19b-3p levels were significantly higher in those with chronic SCI and severe neuropathic pain versus those with chronic SCI and no neuropathic pain. In confirmatory studies, both hsa-miR-19a-3p and hsa-miR-19b-3p have moderate to strong discriminative ability to distinguish between those with and without pain. After adjusting for opioid use, hsa-miR-19b-3p levels were positively associated with pain interference with mood. Because hsa-miR-19 levels have been shown to change in response to exercise, folic acid, and resveratrol, these studies suggest that miRNAs are potential targets of therapeutic interventions.

A Roadmap for Disruptive Applications and Heterogeneous Integration Using Two-Dimensional Materials: State-of-the-Art and Technological Challenges.

This Mini Review attempts to establish a roadmap for two-dimensional (2D) material-based microelectronic technologies for future/disruptive applications with a vision for the semiconductor industry to enable a universal technology platform for heterogeneous integration. The heterogeneous integration would involve integrating orthogonal capabilities, such as different forms of computing (classical, neuromorphic, and quantum), all forms of sensing, digital and analog memories, energy harvesting, and so forth, all in a single chip using a universal technology platform. We have reviewed the state-of-the-art 2D materials such as graphene, transition metal dichalcogenides, phosphorene and hexagonal boron nitride, and so forth, and how they offer unique possibilities for a range of futuristic/disruptive applications. Besides, we have discussed the technological and fundamental challenges in enabling such a universal technology platform, where the world stands today, and what gaps are required to be filled.

A comprehensive review on biomarkers associated with painful temporomandibular disorders.

Pain of the orofacial region is the primary complaint for which patients seek treatment. Of all the orofacial pain conditions, one condition that possess a significant global health problem is temporomandibular disorder (TMD). Patients with TMD typically frequently complaints of pain as a symptom. TMD can occur due to complex interplay between peripheral and central sensitization, endogenous modulatory pathways, and cortical processing. For diagnosis of TMD pain a descriptive history, clinical assessment, and imaging is needed. However, due to the complex nature of pain an additional step is needed to render a definitive TMD diagnosis. In this review we explicate the role of different biomarkers involved in painful TMD. In painful TMD conditions, the role of biomarkers is still elusive. We believe that the identification of biomarkers associated with painful TMD may stimulate researchers and clinician to understand the mechanism underlying the pathogenesis of TMD and help them in developing newer methods for the diagnosis and management of TMD. Therefore, to understand the potential relationship of biomarkers, and painful TMD we categorize the biomarkers as molecular biomarkers, neuroimaging biomarkers and sensory biomarkers. In addition, we will briefly discuss pain genetics and the role of potential microRNA (miRNA) involved in TMD pain.

Changes in Hematological Parameters by Quantifying HRCT Chest Results in Patients With COVID-19 in Tertiary Care Hospital.

AIM: To find changes in hematologic parameters in patients who are COVID-19-positive with respect to high resolution computed tomography (HRCT) chest scan so that the exact picture of the disease course can be identified and an adequate treatment protocol can be planned to combat the COVID-19 pandemic. METHODS: Patients' health-related data including age, gender, symptomatology, associated co-morbidities, laboratory test results and HRCT results were collected. RESULTS: The radiologic findings showed ground glass opacities (GGOs) was the most common manifestation. Analysis of HRCTs of patients with COVID-19 showed that lesions were mainly confined to the right and left lower lobes, suggesting that the COVID-19 virus is mainly harbored in the basal areas of the lungs. CONCLUSION: Radiologic and laboratory investigations can greatly help in early detection of COVID-19, thus allowing for timely interventions.

Introduction of Near to Far Infrared Range Direct Band Gaps in Graphene: A First Principle Insight.

Lack of band gaps hinders application of graphene in the fields like logic, optoelectronics, and sensing despite its various extraordinary properties. In this work, we have done systematic investigations on direct band gap opening in graphene by hydrogenation and fluorination of carbon vacancies using the density functional theory computational approach. We have seen that although a carbon vacancy (void) opens an indirect band gap in graphene, it also creates unwanted mid gap (trap) states, which is attributed to unbound orbitals of the nearest unsaturated carbon atoms at the vacant site. The unsaturated carbon atoms and corresponding trap states can degrade the stability of graphene and create band gaps particularly for large size vacancies. We have proposed that hydrogenation or fluorination of the unsaturated carbon atoms near the vacant site helps in disappearance of the trap states while contributing to promising direct band gaps in graphene. The opened band gap is tunable in the infrared regime and persists for different sizes and densities of hydrogenated or fluorinated patterns. In addition, we have also found that the proposed approach is thermodynamically favorable as well as stable. This keeps the planar nature of the graphene monolayer, despite creation of defects and subsequent functionalization, thereby making it useful for 2D material-based electronics, optoelectronics, and sensing applications.

Complete Blood-count-based Inflammatory Score (CBCS) of COVID-19 Patients at Tertiary Care Center.

CONTEXT: Inflammation is a significant factor driving the rise of multiple cases of viral pneumonia, including COVID-19 infection. Peripheral white blood cells (WBCs), the neutrophil (NEU)-to-lymphocyte (LYM) ratio (NLR), the platelet-to-lymphocyte (PLR) ratio, and hemoglobin (Hb) are markers of systematic inflammatory reaction and often predict disease severity. OBJECTIVE: The current study intended to examine the prognostic importance of hemoglobin (Hb), total leukocyte count (TLC), absolute neutrophile count (ANC), absolute lymphocyte count (ALC), NLR, d-NLR [derived NLR = ANC/(WBC-ANC)], absolute platelet count (APC), and PLR, based on complete blood counts (CBCs) for COVID-19 patients. DESIGN: The research team designed a retrospective that was conducted between March 27 and June 5, 2020, after the first COVID-19 case was reported in Ajmer, Rajasthan, India on March 27. SETTING: The study took place at Jawaharlal Nehru (JLN) Medical College in Ajmer, Rajasthan, India. PARTICIPANTS: The study included 364 participants who were all COVID-positive patients who came to the hospital during the study's period, including patients from various age groups and of both genders. OUTCOME MEASURES: Using the results of the CBC, the research team measured: (1) Hb in g/dl, (2) ANC, (3) ALC, and (4) APC. The neutrophil-lymphocyte ratio (NLR) and the platelet-lymphocyte ratio (PLR) were calculated from measurements of the levels of the circulating biomarkers, as cells × 103/µl. RESULT: For participants who were severely symptomatic, the mean age was 57.86 ± 8.92. Males were more likely to experience severe symptoms. Participants' Hb values were significantly different between groups, and TLC, ANC, NLR, d-NLR, and PLR were highest in the severely symptomatic group and lowest in the asymptomatic group. NLR was positively associated with a risk of COVID-19 pneumonia, while Hb was negatively associated with development of pneumonia. CONCLUSIONS: Disease severity and age are independent predictors of poor outcomes. The NLR should be used as a routine blood test that can help in the diagnosis of disease severity in COVID-19. NLR is very simple tool that can be used as a fast and low-cost test that is easily available, even in small centers where the facilities for other tests, such as tests of LDH, CRP, and IL-6, and high resolution CT scans aren't available. Thus, NLR can be used as single independent predictor of COVID-19 disease severity.

Stone-Wales Defect and Vacancy-Assisted Enhanced Atomic Orbital Interactions Between Graphene and Ambient Gases: A First-Principles Insight.

Graphene has magnificent fundamental properties for its application in various fields. However, these fundamental properties have been observed to get perturbed by various agents like intrinsic defects and ambient gases. Degradation as well as p-type behavior of graphene under an ambient atmosphere are some of the properties that have not yet been explored extensively. In this work, interactions of different ambient gases, like N2, O2, Ar, CO2, and H2O, with pristine and defective graphene are studied using density functional theory (DFT) computations. It is observed that while the pristine graphene is chemically and physically inert with ambient gases, except for oxygen, its interaction with these ambient gases increases significantly in the presence of carbon vacancies and Stone-Wales (SW) defects. We report that Ar and N2 are apparently not inert with defective graphene, as they also influence its fundamental properties like band structure, mid gap (trap) states, and Fermi energy level. We have also found that while oxygen makes pristine graphene p-type, the phenomenon amplifies in the presence of SW defects. Besides, in the presence of carbon vacancies, N2, H2O, and CO2 also make the graphene monolayer p-type. Among ambient gases, oxygen is the real performance and reliability killer for graphene. Its reaction is seeded by a carbon vacancy, which initiates its degradation by local formation of graphene oxide.

Visualizing Oxidation Mechanisms in Few-Layered Black Phosphorus via In Situ Transmission Electron Microscopy.

Layered two-dimensional (2D) black phosphorus (BP) exhibits novel semiconducting properties including a tunable bandgap and high electron mobility. However, the poor stability of BP in ambient environment severely limits potential for application in future electronic and optoelectronic devices. While passivation or encapsulation of BP using inert materials/polymers has emerged as a plausible solution, a detailed fundamental understanding of BP's reaction with oxygen is imperative to rationally advance its use in applications. Here, we use in situ environmental transmission electron microscopy to elucidate atomistic structural changes in mechanically exfoliated few-layered BP during exposure to varying partial pressures of oxygen. An amorphous oxide layer is seen on the actively etching BP edges, and the thickness of this layer increases with increasing oxygen partial pressure, indicating that oxidation proceeds via initial formation of amorphous PxOy species which sublime to result in the etching of the BP crystal. We observe that while few-layered BP is stable under the 80 kV electron beam (e-beam) in vacuum, the lattice oxidizes and degrades at room temperature in the presence of oxygen only in the region under the e-beam. The oxidative etch rate also increases with increasing e-beam dosage, suggesting the presence of an energy barrier for the oxidation reaction. Preferential oxidative etching along the [0 0 1] and [0 0 1] crystallographic directions is observed, in good agreement with density functional theory calculations showing favorable thermodynamic stability of the oxidized BP (0 0 1) planes compared to the (1 0 0) planes. We expect the atomistic insights and fundamental understanding obtained here to aid in the development of novel approaches to integrate BP in future applications.

Correlation of Thyroid Hormone Profile with Biochemical Markers of Renal Function in Patients with Undialyzed Chronic Kidney Disease.

OBJECTIVE: The present study was conducted to evaluate the correlation of renal functions with thyroid hormone levels in patients with undialyzed chronic kidney disease (CKD). Literature shows significant alteration in thyroid hormone function tests in CKD patients who are receiving long-standing dialysis treatment. However, not much is described in those receiving conservative management without dialysis. Although CKD is associated with an increased prevalence of primary hypothyroidism, various studies on thyroid hormone status in uremic patients have reported conflicting results. METHODOLOGY: Thyroid hormone levels and biochemical markers of renal function were estimated in 30 undialyzed CKD patients and similar number of age- and sex-matched healthy controls, followed by statistical analysis and correlation. RESULTS: Free triiodothyronine (FT3) and free thyroxine (FT4) were found to be significantly reduced (P < 0.001 for each) in undialyzed CKD patients whereas thyroid-stimulating hormone (TSH) levels showed statistically insignificant alteration in both groups. We also observed that urea and creatinine were negatively correlated whereas creatinine clearance was positively correlated with both FT3 and FT4 having high statistical (two tailed) significance with P < 0.001. Nonsignificant correlation was seen between blood urea and TSH (r = 0.236, P = 0.069), creatinine clearance, and TSH (r = 0.206, P = 0.114 Pearson's correlation coefficient). There is just significant positive correlation between the serum creatinine values and TSH (r = 0.248, P = 0.049). CONCLUSIONS: Thyroid hormones were significantly decreased in undialyzed CKD patients as compared to healthy controls.