Ionic Covalent Organic Framework as a Dual Functional Sensor for Temperature and Humidity.

Visual sensing of humidity and temperature by solids plays an important role in the everyday life and in industrial processes. Due to their hydrophobic nature, most covalent organic framework (COF) sensors often exhibit poor optical response when exposed to moisture. To overcome this challenge, the optical response is set out to improve, to moisture by incorporating H-bonding ionic functionalities into the COF network. A highly sensitive COF, consisting of guanidinium and diformylpyridine linkers (TG-DFP), capable of detecting changes in temperature and moisture content is fabricated. The hydrophilic nature of the framework enables enhanced water uptake, allowing the trapped water molecules to form a large number of hydrogen bonds. Despite the presence of non-emissive building blocks, the H-bonds restrict internal bond rotation within the COF, leading to reversible fluorescence and solid-state optical hydrochromism in response to relative humidity and temperature.

Development of a Many-Body Force Field for Aqueous Alkali Metal and Halogen Ions: An Energy Decomposition Analysis Guided Approach.

Aqueous solutions of alkyl/alkaline metal and halide ions play a crucial functional role in biological systems such as proteins, membranes, and nucleic acids and for interfacial chemistry in geomedia and in the atmosphere. We present the MB-UCB many-body force field for monovalent and divalent ions that includes polarization, charge penetration to describe the short-range permanent electrostatics accurately, as well as a model for charge transfer to better describe the quantum mechanical potential energy surface and its components obtained from the absolutely localized molecular orbital energy decomposition analysis (ALMO-EDA). We find that the MB-UCB force field is in very good agreement with a validation suite of ion-ion and ion-water cluster data, exhibiting overall better cancellation of errors among energy components, unlike the case for other many-body potentials that do not utilize an EDA scheme. However, limitations in the functional form for the classical many-body energy components do limit the best achievable accuracy through complete cancellation of error and warrant further study.

New Threat at Doorstep: What an Intensivist should Know.

How to cite this article: Das AK, Sharma A, Kumar S, Goyal S, Kothari N. New Threat at Doorstep: What an Intensivist should Know. Indian J Crit Care Med 2022;26(10):1076-1077.

Comparative Evaluation of C-MAC Videolaryngoscope with Macintosh Direct Laryngoscope in Patients with Normal Airway Predictors.

Background: Video laryngoscopes (VL) assist in securing the airway faster and more accurately in difficult airways. However, data regarding its usefulness in patients with normal airways are sparse. Aim: We designed this study to compare the ease and success of endotracheal intubation between C-MAC and Macintosh direct laryngoscope (DL) in adult patients with no anticipated airway difficulty. Settings and Design: The design involves prospective randomized case - control study. Subjects and Methods: One hundred and twenty adult patients with predicted normal airway were randomized into two groups and were intubated using VL (C-MAC VL) and DL (Macintosh DL), respectively. The Cormack-Lehane (CL) grade, time taken for intubation, attempts taken (number), and need for laryngeal maneuvers or stylets were recorded and analyzed for statistical significance. Results: Thirty-eight patients in the DL group and 48 patients in the VL group had CL I view, 20 patients in the DL group and 16 patients in the VL group had CL II, and two patients in the DL group had CL III view. None of the patients in Group VL had CL III view. In seven out of 60 cases in the DL group, difficulty was experienced during insertion of the laryngoscope blade as compared to two cases out of 60 in the VL group. The mean time taken for intubation was lesser in Group DL (28.48 s) as compared to 39.3 s in Group VL. Nine patients in Group DL and 16 patients in Group VL required external laryngeal manipulation. Stylets were used, in seven patients in group DL and in 11 patients in group VL. Conclusions: In patients with a predicted normal airway, C-MAC provides a better glottic view compared to Macintosh DL. Time taken for intubation using the C-MAC video laryngoscope was more. However, success rates on the first attempt at endotracheal intubation and the number of intubation attempts with either laryngoscope were similar.

Social Stigma of COVID-19 Experienced by Frontline Healthcare Workers of Department of Anaesthesia and Critical Care of a Tertiary Healthcare Institution in Delhi.

BACKGROUND: Social stigma is associated with Coronavirus Disease-2019 (COVID-19) particularly against people who have contracted the disease or have come in contact with it. There is paucity of studies regarding the prevalence of social stigma against healthcare workers (HCWs) in COVID-19 hospitals in India. The objective of this study was to measure social stigma faced by frontline HCWs of Department of Anaesthesia and Critical Care in a COVID-19 hospital and to assess the relationship between sociodemographic characteristics and social stigma. PATIENTS AND METHODS: A cross-sectional study using a questionnaire (sociodemographic characteristics along with modified Berger HIV Stigma Scale) was conducted from October 10, 2020 to October 30, 2020, in the Department of Anaesthesia and Critical Care. The survey was distributed among frontline HCWs using Google Forms as well as Bilingual Physical Form. Total stigma and subgroups of stigma scale were measured for different sociodemographic parameters and compared. Data were presented as mean ± standard deviation. p-value <0.05 was taken as significant. RESULTS: Out of 120 frontline HCWs participated in the study, 68 (56.6%) reported severe level of COVID-19-related stigma. The mean score of COVID-19-related stigma was 41 + 7.69. Mean scores for subgroups of stigma scale, i.e., personalized stigma, disclosure concerns, negative self-image, and concerns with public attitude, were 15.60 + 4.01, 6.68 + 3.21, 5.46 + 3.22, and 13.25 + 2.44, respectively. In the univariate analysis, the overall COVID-19-related stigma scores were associated with age >30 years, male gender, lower designation (technicians and nursing orderly), lesser education, and married HCWs. In logistic regression model, only male gender was significantly associated with severity of COVID-19 stigma. CONCLUSION: This study concluded that more than half of frontline HCWs in the Department of Anaesthesia and Critical Care experienced severe social stigma during COVID-19 pandemic, with highest stigma in concerns with public attitude subgroup. Severity of stigma was associated with age, male gender, designation, education, and marital status of HCW. HIGHLIGHTS: Frontline HCWs of Department Anaesthesia and Critical Care experienced significant stigma related to COVID-19. HOW TO CITE THIS ARTICLE: Jain S, Das AK, Talwar V, Kishore J, Heena, Ganapathy U. Social Stigma of COVID-19 Experienced by Frontline Healthcare Workers of Department of Anaesthesia and Critical Care of a Tertiary Healthcare Institution in Delhi. Indian J Crit Care Med 2021;25(11):1241-1246.

A Reactive Force Field with Coarse-Grained Electrons for Liquid Water.

Nonreactive force fields are defined by perturbations of electron density that are relatively small, whereas chemical reactivity involves wholesale electronic rearrangements that make and break bonds. Thus, reactive force fields are incredibly difficult to develop compared to nonreactive force fields, yet at the same time, they fill a critical need when ab initio molecular dynamics methods are not affordable. We introduce a new reactive force field model for water that combines modified nonbonded terms of the ReaxFF model and its embedding in the electrostatic interactions described by our recently introduced coarse-grained electron model (C-GeM). The ReaxFF/C-GeM force field is characterized for many energetic and dissociative water properties for water clusters, structure, and dynamical properties under ambient conditions in the condensed phase, as well as the temperature dependence of density and water diffusion, with very good agreement with experiment. The ReaxFF/C-GeM force field should be more transferable and more broadly applicable to a range of reactive systems involving both proton and electron transfer in the condensed phase.

Multi-State VALBOND for Atomistic Simulations of Hypervalent Molecules, Metal Complexes, and Reactions.

The implementation, validation, and application of the multi-state VALBOND method for transition-metal-containing and hypervalent molecules are presented. This approach is particularly suited for molecules with unusual shapes and systems that need to be described by a superposition of resonance structures, each of which satisfies the octet rule. The implementation is based on the original VALBOND force field and allows us to smoothly switch between resonance structures, each of which can be characterized by its own force field, including varying charge distributions and coupling terms between the states. The implementation conserves total energy for simulations in the gas phase and in solution and is applied to a number of topical systems. For the small hypervalent molecule ClF3, the barrier for pseudorotation is found to be 4.3 kcal/mol, which compares favorably with the experimentally measured value of 4.8 kcal/mol. A transition-metal-containing complex, cisplatin, is characterized by six resonance states, for which the vibrational spectrum is found to be in good agreement with experiment. Finally, umbrella sampling simulations of the SN2 reaction BrMe + Cl- → Br- + MeCl in solution yield a barrier height of 24.6 kcal/mol, in good agreement with experiment (24.7 kcal/mol).

Kinetic Analysis and Structural Interpretation of Competitive Ligand Binding for NO Dioxygenation in Truncated Hemoglobin†N.

The conversion of nitric oxide (NO) into nitrate (NO3- ) by dioxygenation protects cells from lethal NO. Starting from NO-bound heme, the first step in converting NO into benign NO3- is the ligand exchange reaction FeNO+O2 →FeO2 +NO, which is still poorly understood at a molecular level. For wild-type (WT) truncated hemoglobin N (trHbN) and its Y33A mutant, the calculated barriers for the exchange reaction differ by 1.5 kcal mol-1 , compared with 1.7 kcal mol-1 from experiment. It is directly confirmed that the ligand exchange reaction is rate-limiting in trHbN and that entropic contributions account for 75 % of the difference between the WT and the mutant. Residues Tyr 33, Phe 46, Val 80, His 81, and Gln 82 surrounding the active site are expected to control the reaction path. By comparison with electronic structure calculations, the transition state separating the two ligand-bound states was assigned to a 2 A state.

Copper Oxidation/Reduction in Water and Protein: Studies with DFTB3/MM and VALBOND Molecular Dynamics Simulations.

We apply two recently developed computational methods, DFTB3 and VALBOND, to study copper oxidation/reduction processes in solution and protein. The properties of interest include the coordination structure of copper in different oxidation states in water or in a protein (plastocyanin) active site, the reduction potential of the copper ion in different environments, and the environmental response to copper oxidation. The DFTB3/MM and VALBOND simulation results are compared to DFT/MM simulations and experimental results whenever possible. For a copper ion in aqueous solution, DFTB3/MM results are generally close to B3LYP/MM with a medium basis, including both solvation structure and reduction potential for Cu(II); for Cu(I), however, DFTB3/MM finds a two-water coordination, similar to previous Born-Oppenheimer molecular dynamics simulations using BLYP and HSE, whereas B3LYP/MM leads to a tetrahedron coordination. For a tetraammonia copper complex in aqueous solution, VALBOND and DFTB3/MM are consistent in terms of both structural and dynamical properties of solvent near copper for both oxidation states. For copper reduction in plastocyanin, DFTB3/MM simulations capture the key properties of the active site, and the computed reduction potential and reorganization energy are in fair agreement with experiment, especially when the periodic boundary condition is used. Overall, the study supports the value of VALBOND and DFTB3(/MM) for the analysis of fundamental copper redox chemistry in water and protein, and the results also help highlight areas where further improvements in these methods are desirable.