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1.
Indian J Crit Care Med ; 27(2): 89-92, 2023 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-36865517

RESUMEN

Background: The Curing Coma Campaign (CCC) was launched by the Neurocritical Care Society (NCS) in 2019, with the purpose to bring together a diverse group of coma scientists, neurointensivists, and neurorehabilitationists. Methods: The aim of this campaign is to move beyond the limitations imposed by current definitions of coma and identify mechanisms to improve prognostication, identify test therapies, and impact outcomes. At the moment, whole approach of the CCC appears ambitiously challenging. Results: This could be true only for the Western world, such as the North America, Europe, and few developed countries. However, the whole concept of CCC may face potential challenges in the lower-middle income countries. India has several stumbling blocks that need to and can be addressed in the future, for a meaningful outcome, as envisaged in the CCC. Conclusion: India has several potential challenges, which we aim to discuss in this article. How to cite this article: Kapoor I, Mahajan C, Zirpe KG, Samavedam S, Sahoo TK, Sapra H, et al. The Curing Coma Campaign®: Concerns in the Indian Subcontinent. Indian J Crit Care Med 2023;27(2):89-92.

2.
Am J Infect Control ; 50(12): 1368-1373, 2022 12.
Artículo en Inglés | MEDLINE | ID: mdl-35181374

RESUMEN

BACKGROUND: Healthcare-associated infections (HAIs) are a significant threat in healthcare settings. Since nurses have the most day-to-day contact with patients, their knowledge about infection control (IC) practices is crucial in preventing HAIs. We therefore conducted a study to assess the knowledge and awareness of IC practices amongst nurses across hospitals in India. METHODS: An online survey-based, cross-sectional, descriptive study for nurses was conducted in July-August 2021, through a multiple-choice questionnaire, administered via a web-based link across 13 hospitals from various cities of India. Five different aspects of IC knowledge were assessed including general IC, standard precautions, transmission-based precautions, bundle care knowledge, and COVID-19 related knowledge. RESULTS: Complete data filled by 1,000 nurses was analyzed. The knowledge of nurses varied across different aspects of IC. A statistically significant association was found between the IC knowledge and the years of experience (P = .003) and the area of working (critical vs semi-critical areas) (P < .001) of nurses. A statistically significant difference was also found in the knowledge of nurses from different hospitals depending upon the accreditation (P < .001) and the teaching status (P = .035), but no significant difference based on the city category of hospital (P > .05). Accreditation showed the strongest association {ß = 2.499 (95% CI = 1.67-3.32)} while non-teaching status had a negative impact {ß = -1.76 (95% CI = 2.543 to -2.543)} on knowledge using multivariate linear regression analysis. CONCLUSIONS: Infection prevention and control is the biggest challenge in any hospital and improving the knowledge and awareness of the nurses on the same is fundamental to its success. A multifaceted approach of continuing education programs, training, and feedback should be undertaken towards improving the awareness and compliance to IC practices.


Asunto(s)
COVID-19 , Infección Hospitalaria , Humanos , Estudios Transversales , Conocimientos, Actitudes y Práctica en Salud , COVID-19/prevención & control , Control de Infecciones , Infección Hospitalaria/prevención & control , Encuestas y Cuestionarios
3.
Chemosphere ; 288(Pt 2): 132472, 2022 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-34634271

RESUMEN

Green synthesis of manganese oxide nanoparticles (NPs) was carried out by sol-gel method using Acacia Concinna fruit extract for removal of reactive dye. The effect of calcination temperature on its morphology was investigated. α-MnO2 and Mn3O4 NPs were synthesized at 400 °C and 900 °C respectively and were characterized by PXRD, SEM, TEM, FTIR, BET, Raman and TGA. As-synthesized MnO2 NPs were investigated for the adsorption of Reactive Blue 21 (RB-21) dye. The effect of pH, adsorbent dose, agitation speed, initial dye concentration and temperature on dye removal was explored. pHpzc was calculated from zeta potential study showing positive surface charge below pH 3.18 resulting in electrostatic force of attraction between adsorbate and adsorbent. Both linear and non-linear regression approaches were utilised for the fitting of kinetic models and adsorption isotherms. Adsorption data follows a pseudo second order kinetics and fits well with the Freundlich isotherm model. Thermodynamic parameters such as ΔHo, ΔSo and ΔGo were determined. The dye removal efficiency, in case of MnO2 NPs at pH 3.0 was obtained to be 98% whereas for Mn3O4, no such dye adsorption was observed. The mechanism of adsorption was studied theoretically confirming π-π interaction and H-bonding between the MnO2 and RB dye molecules.


Asunto(s)
Compuestos de Manganeso , Nanopartículas , Adsorción , Óxidos , Temperatura
4.
Front Plant Sci ; 13: 1048696, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36589118

RESUMEN

Biological nitrogen fixation is the most important eco-friendly approach to nitrogenous fertilizer management in the rhizosphere. Rhizobium is considered the most important symbiotic N-fixing microorganism. Native strains of Rhizobium perform better than the non-native strains by getting ambient conditions for growth and proliferation. Native strains enhance the soil fertility and productivity of pulses. The study was carried out in three phases, i.e., pot experiment, field experiment, and farmers' field demonstrations. In a pot experiment, two isolated rhizobia were inoculated to seeds of French bean (Phaseolus vulgaris) and applied with and without lime to evaluate crop growth, photosynthetic activity, and nodule characteristics of the target crop. In the field, strains were inoculated to seeds of French bean, which received different combinations of inputs- inorganic fertilizers, lime, and boron- to study the influence of native stains on crop productivity and agronomic efficiency. In comparison to non-limed packaging, the amounts of chlorophyll a, chlorophyll b, total chlorophyll, and chlorophyll a:b were, respectively, 13% to 30%, 1% to 15%, 10% to 27%, and 1% to 20% greater in limed packages. In limed packages compared to non-limed packages, the root length, biomass, density, and growth rate were increased by 16% to 17%, 36% to 52%, 38% to 49%, and 36% to 52%, respectively. In contrast to non-limed packages, limed packages had nodule attributes like the number of nodules per plant and nodular weight, which were 28% to 41% and 33% to 37% greater, respectively. Inoculation of native rhizobia strains with liming to acid soil increased 46% to 72% of leaf nitrogen content over non-limed rhizobia inoculated packages. In a field experiment, the adoption of soil test-based fertilizer application had an advantage of 25% in pod yield over farmers' practice. Acid soil amelioration with lime improved pod yield from 14% to 39% over non-limed packages. Farmers' field demonstration recorded the highest pod yield in the package where seeds were inoculated with S2 (RBHR-21) strain added with soil test-based fertilizers (STD) followed by STD + S1 (RBHR-15) with 98% and 84% increase over farmers' practice. However, experimental evidence favored using both strains for bio-inoculation of the French bean crop.

5.
J Chem Phys ; 154(24): 244305, 2021 Jun 28.
Artículo en Inglés | MEDLINE | ID: mdl-34241367

RESUMEN

A path integral ground state (PIGS) approach for the simulation of asymmetric top rotors is presented. The method is based on Monte Carlo sampling of angular degrees of freedom. A symmetry-adapted rotational density matrix is used to account for nuclear spin statistics. To illustrate the method, ground-state properties of collections of para-water molecules confined to a one-dimensional lattice are computed. Those include energetic and structural observables. An advantage of the PIGS method is that expectation values can be obtained directly since the square of the wavefunction is sampled during a simulation. To benchmark the method, ground state energies and orientational distributions are computed using exact diagonalization for a single para-water molecule in an external field using a finite basis of symmetric top eigenfunctions. Benchmark results are also provided for N = 2 para-water molecules pinned to lattice sites at various distances to sample the crossover from hydrogen bonding to the dipole-dipole interaction regime. Excellent agreement between the PIGS results and the finite basis set calculations is observed. A thorough analysis of the convergence in terms of the imaginary time propagation length and systematic Trotter error is performed. The PIGS approach is then applied to a chain of N = 11 water molecules, and an equation of state is constructed in terms of the intermolecular separation. Ordering effects are also studied, and a transition between hydrogen bonding to dipole-dipole alignment is observed. The method is scalable and can also be applied in higher dimensions.

6.
Anaesthesiol Intensive Ther ; 53(3): 265-270, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34006054

RESUMEN

The COVID-19 pandemic has tested the very elements of human factors and ergonomics (HFE) to their maximum. HFE is an established scientific discipline that studies the interrelationship between humans, equipment, and the work environment. HFE includes situation awareness, decision making, communication, team working, leadership, managing stress, and coping with fatigue, empathy, and resilience. The main objective of HF is to optimise the interaction of humans with their work environment and technical equipment in order to maximise patient safety and efficiency of care. This paper reviews the importance of HFE in helping intensivists and all the multidisciplinary ICU teams to deliver high-quality care to patients in crisis situations.


Asunto(s)
COVID-19/terapia , Ergonomía , Unidades de Cuidados Intensivos , SARS-CoV-2 , COVID-19/epidemiología , Comunicación , Humanos , Liderazgo , Seguridad del Paciente , Resiliencia Psicológica
7.
J Phys Chem A ; 125(3): 731-745, 2021 Jan 28.
Artículo en Inglés | MEDLINE | ID: mdl-33461293

RESUMEN

The dynamics of the H + H2+ reaction has been analyzed from the electronically first excited state of diabatic potential energy surfaces constructed by employing the Beyond Born-Oppenheimer theory [J. Chem. Phys. 2014, 141, 204306]. We have employed the coupled 3D time-dependent wavepacket formalism in hyperspherical coordinates for multisurface reactive scattering problems. To be specific, the charge transfer processes have been investigated extensively by calculating state-to-state as well as total reaction probabilities and integral cross sections, when the reaction process is initiated from the first excited electronic state (21A'). We have depicted the convergence profiles of reaction probabilities for the competing charge transfer processes, namely, reactive charge transfer (RCT) and nonreactive charge transfer (NRCT) processes for different total energies with respect to total angular momentum, J. Total and state-to-state integral cross sections are calculated as a function of total energy for the initial rovibrational state, namely, v = 0, j = 0 level of H2+ (2Σg+) molecule and are compared with previous theoretical calculations. Finally, we have calculated temperature-dependent rate constants using our presently evaluated cross sections and compared their average with the experimentally measured one.

8.
Indian J Crit Care Med ; 24(Suppl 5): S263-S271, 2020 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-33354050

RESUMEN

The number of cases with novel coronavirus disease-2019 (COVID-19) infection is increasing every day in the world, and India contributes a substantial proportion of this burden. Critical care specialists have accepted the challenges associated with the COVID-19 pandemic and are frontline warriors in this war. They have worked hard in streamlining workflow isolation of positive patients, clinical management of critically ill patients, and infection prevention practices. With no end in sight for this pandemic, intensive care unit (ICU) practitioners, hospital administrators, and policy makers have to join hands to prepare for the surge in critical care bed capacity. In this position article, we offer several suggestions on important interventions to the ICU practitioners for better management of critically ill patients. This position article highlights key interventions for COVID-19 treatment and covers several important issues such as endotracheal intubation and tracheostomy (surgical vs PCT), nebulization, bronchoscopy, and invasive procedures such as central venous catheters, arterial lines, and HD catheters. How to cite this article: Pande RK, Bhalla A, SN Myatra, Yaddanpuddi LN, Gupta S, Sahoo TK, et al. Procedures in COVID-19 Patients: Part-I. Indian J Crit Care Med 2020;24(Suppl 5):S263-S271.

9.
Indian J Crit Care Med ; 24(Suppl 5): S272-S279, 2020 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-33354051

RESUMEN

Critical care in the era of novel coronavirus disease-2019 (COVID-19) infection has multiple challenges including management of the patient, underlying comorbidities, and the complications. With no end in sight to the pandemic, intensive care unit (ICU) practitioners and hospital administrators have to join hands to prepare for the long battle ahead. Critically ill COVID-19 patients need imaging or image-guided interventions in one form or the other including X-rays, ultrasonography (USG), echocardiography (ECHO), and CT scan. These patients often require renal replacement therapy (RRT) for either the preexisting chronic renal insufficiency or acutely developing kidney injury. Another important component of care is transfer of the patient to and fro from the ICU or to higher care centers. Most of the ICUs are equipped with modern facilities but with increasing number of patients a large number of makeshift arrangements are being made for managing these patients. This position paper outlines important tips to formulate protocols and procedures for critically ill patients, who are managed in the ICU. How to cite this article: Pande RK, Bhalla A, Myatra SN, Yaddanpuddi LN, Gupta S, Sahoo TK, et al. Procedures in COVID-19 Patients: Part-II. Indian J Crit Care Med 2020;24(Suppl 5):S272-S279.

10.
Indian J Crit Care Med ; 24(8): 731-734, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-33024387

RESUMEN

Polymyositis (PM) is an uncommon inflammatory myopathy that affects striated muscles. It causes weakness of the limb girdles, neck, and pharyngeal muscles. We are presenting a case of PM which manifested after intrauterine death (IUD). The patient was referred to our hospital for breathing difficulty, 4 days after delivery of a dead fetus. Initially, she was treated in line of puerperal sepsis and peripartum cardiomyopathy. Patient's cardiopulmonary functions improved but she had persistent high-grade fever. Gross muscle weakness was found on day 5 of admission, involving all four limbs, predominantly in proximal muscles and she had dark colored urine. Laboratory tests revealed myoglobinuria, high serum creatine phosphokinase (CPK) levels, and high lactate dehydrogenase (LDH) levels. Polymyositis diagnosed on the basis of high CPK levels, magnetic resonance imaging (MRI) of cervical spine, electromyography (EMG), and muscle biopsy findings. We question, whether the PM could be pathogenically related to the pregnancy? Literature review of the previously reported cases of PM/dermatomyositis and our case report suggests that pregnancy can trigger the new onset of PM. HOW TO CITE THIS ARTICLE: Borse MP, Sahoo TK, Anand KV, Kumar M, Panda D. Postpartum Polymyositis Following Intrauterine Fetal Death. Indian J Crit Care Med 2020;24(8):731-734.

11.
J Chem Phys ; 152(18): 184113, 2020 May 14.
Artículo en Inglés | MEDLINE | ID: mdl-32414240

RESUMEN

We calculate the second Rényi entanglement entropy for systems of interacting linear rotors in their ground state as a measure of entanglement for continuous rotational degrees of freedom. The entropy is defined in relation to the purity of a subsystem in a bipartite quantum system, and to compute it, we compare two sampling ensembles based on the path integral ground state (PIGS) formalism. This scheme centers on the replica trick and is aided by the ratio trick, both developed in this context by Hastings et al. [Phys. Rev. Lett. 104, 157201 (2010)]. We study a system composed of linear quantum rotors on a lattice in one dimension, interacting via an anisotropic dipole-dipole potential. The ground state second Rényi entropies estimated by PIGS are benchmarked against those from the density matrix renormalization group for various interaction strengths and system sizes. We find that the entropy grows with an increase in interaction strength, and for large enough systems, it appears to plateau near log(2). We posit that the limiting case of many strongly interacting rotors behaves akin to a lattice of two-level particles in a cat state, in which one naturally finds an entanglement entropy of log(2).

12.
Indian J Crit Care Med ; 24(Suppl 1): S6-S30, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-32205954

RESUMEN

BACKGROUND AND PURPOSE: Short-term central venous catheterization (CVC) is one of the commonly used invasive interventions in ICU and other patient-care areas. Practice and management of CVC is not standardized, varies widely, and need appropriate guidance. Purpose of this document is to provide a comprehensive, evidence-based and up-to-date, one document source for practice and management of central venous catheterization. These recommendations are intended to be used by critical care physicians and allied professionals involved in care of patients with central venous lines. METHODS: This position statement for central venous catheterization is framed by expert committee members under the aegis of Indian Society of Critical Care Medicine (ISCCM). Experts group exchanged and reviewed the relevant literature. During the final meeting of the experts held at the ISCCM Head Office, a consensus on all the topics was made and the recommendations for final document draft were prepared. The final document was reviewed and accepted by all expert committee members and after a process of peer-review this document is finally accepted as an official ISCCM position paper.Modified grade system was utilized to classify the quality of evidence and the strength of recommendations. The draft document thus formulated was reviewed by all committee members; further comments and suggestions were incorporated after discussion, and a final document was prepared. RESULTS: This document makes recommendations about various aspects of resource preparation, infection control, prevention of mechanical complication and surveillance related to short-term central venous catheterization. This document also provides four appendices for ready reference and use at institutional level. CONCLUSION: In this document, committee is able to make 54 different recommendations for various aspects of care, out of which 40 are strong and 14 weak recommendations. Among all of them, 42 recommendations are backed by any level of evidence, however due to paucity of data on 12 clinical questions, a consensus was reached by working committee and practice recommendations given on these topics are based on vast clinical experience of the members of this committee, which makes a useful practice point. Committee recognizes the fact that in event of new emerging evidences this document will require update, and that shall be provided in due time. ABBREVIATIONS LIST: ABHR: Alcohol-based hand rub; AICD: Automated implantable cardioverter defibrillator; BSI: Blood stream infection; C/SS: CHG/silver sulfadiazine; Cath Lab: Catheterization laboratory (Cardiac Cath Lab); CDC: Centers for Disease Control and Prevention; CFU: Colony forming unit; CHG: Chlorhexidine gluconate; CL: Central line; COMBUX: Comparison of Bedside Ultrasound with Chest X-ray (COMBUX study); CQI: Continuous quality improvement; CRBSI: Catheter-related blood stream infection; CUS: Chest ultrasonography; CVC: Central Venous Catheter; CXR: Chest X-ray; DTTP: Differential time to positivity; DVT: Deep venous thrombosis; ECG: Electrocardiography; ELVIS: Ethanol lock and risk of hemodialysis catheter infection in critically ill patients; ER: Emergency room; FDA: Food and Drug Administration; FV: Femoral vein; GWE: Guidewire exchange; HD catheter: Hemodialysis catheter; HTS: Hypertonic saline; ICP: Intracranial pressure; ICU: Intensive Care Unit; IDSA: Infectious Disease Society of America; IJV: Internal jugular vein; IPC: Indian penal code; IRR: Incidence rate ratio; ISCCM: Indian Society of Critical Care Medicine; IV: Intravenous; LCBI: Laboratory confirmed blood stream infection; M/R: Minocycline/rifampicin; MBI-LCBI: Mucosal barrier injury laboratory-confirmed bloodstream infection; MRSA: Methicillin-resistant Staphylococcus aureus; NHS: National Health Service (UK); NHSN: National Healthcare Safety Network (USA); OT: Operation Theater; PICC: Peripherally-inserted central catheter; PIV: Peripheral intravenous line; PL: Peripheral line; PVI: Povidone-iodine; RA: Right atrium; RCT: Randomized controlled trial; RR: Relative risk; SCV/SV: Subclavian vein; ScVO2: Central venous oxygen saturation; Sn: Sensitivity; SOP: Standard operating procedure; SVC: Superior vena cava; TEE: Transesophageal echocardiography; UPP: Useful Practice Points; USG: Ultrasonography; WHO: World Health Organization. HOW TO CITE THIS ARTICLE: Javeri Y, Jagathkar G, Dixit S, Chaudhary D, Zirpe KG, Mehta Y, et al. Indian Society of Critical Care Medicine Position Statement for Central Venous Catheterization and Management 2020. Indian J Crit Care Med 2020;24(Suppl 1):S6-S30.

13.
J Phys Chem A ; 119(50): 12392-403, 2015 Dec 17.
Artículo en Inglés | MEDLINE | ID: mdl-26436891

RESUMEN

We implement a coupled three-dimensional (3D) time-dependent wave packet formalism for the 4D reactive scattering problem in hyperspherical coordinates on the accurate double many body expansion (DMBE) potential energy surface (PES) for the ground and first two singlet states (1(1)A', 2(1)A', and 3(1)A') to account for nonadiabatic processes in the D(+) + H2 reaction for both zero and nonzero values of the total angular momentum (J). As the long-range interactions in D(+) + H2 contribute significantly due to nonadiabatic effects, the convergence profiles of reaction probabilities for the reactive noncharge transfer (RNCT), nonreactive charge transfer (NRCT), and reactive charge transfer (RCT) processes are shown for different collisional energies with respect to the helicity (K) and total angular momentum (J) quantum numbers. The total and state-to-state cross sections are presented as a function of the collision energy for the initial rovibrational state v = 0, j = 0 of the diatom, and the calculated cross sections compared with other theoretical and experimental results.

14.
J Chem Phys ; 143(6): 064706, 2015 Aug 14.
Artículo en Inglés | MEDLINE | ID: mdl-26277155

RESUMEN

A second order classical perturbation theory is developed to calculate the sticking probability of a particle scattered from an uncorrugated thermal surface. An analytic expression for the temperature dependent energy loss of the particle to the surface is derived by employing a one-dimensional generalized Langevin equation. The surface temperature reduces the energy loss, since the thermal surface transfers energy to the particle. Using a Gaussian energy loss kernel and the multiple collision theory of Fan and Manson [J. Chem. Phys. 130, 064703 (2009)], enables the determination of the fraction of particles trapped on the surface after subsequent momentum reversals of the colliding particle. This then leads to an estimate of the trapping probability. The theory is tested for the model scattering of Ar on a LiF(100) surface. Comparison with numerical simulations shows excellent agreement of the analytical theory with simulations, provided that the energy loss is determined by the second order perturbation theory.

15.
J Chem Phys ; 142(2): 024304, 2015 Jan 14.
Artículo en Inglés | MEDLINE | ID: mdl-25591350

RESUMEN

A recently proposed coupled three-dimensional time-dependent wave-packet formalism in hyperspherical coordinates is shown to yield accurate results for the reactive non-charge transfer process in the title system at collision energies as low as 100 K, where the lowest sheet of the accurate double many body expansion form for the singlet H3 (+) is used. The results are compared with available experimental data as well as time-independent calculations, and the agreement shown to be generally good.

16.
J Phys Chem A ; 118(26): 4837-50, 2014 Jul 03.
Artículo en Inglés | MEDLINE | ID: mdl-24918479

RESUMEN

We explore a coupled three-dimensional (3D) time-dependent wave packet formalism in hyperspherical coordinates for a 4D reactive scattering problem on the lowest adiabatic singlet surface (1(1)A') of the D(+) + H2 reaction. The coupling among the wavepackets arises through quantization of the rotation matrix, which represents the orientation of the three particles in space. The required transformation from Jacobi to hyperspherical coordinates and vice versa during initialization and projection of the wave packet on the asymptotic state(s), and the coupled equations of motion, are briefly discussed. With the long-range potential known to contribute significantly on the D(+) + H2 system, we demonstrate the workability of our approach, where the convergence profiles of the reaction probability for the reactive noncharge transfer (RNCT) process [D(+) + H2(v=0, j=0,1) → HD(v',j') + H(+)] are shown for three different collisional energies (1.7, 2.1, and 2.5 eV) with respect to the helicity (K) and total angular momentum (J) quantum numbers. The calculated reactive cross-section is presented as a function of the collision energy for two different initial states of the diatom (v = 0, j = 0, 1).

17.
J Chem Phys ; 139(3): 034310, 2013 Jul 21.
Artículo en Inglés | MEDLINE | ID: mdl-23883030

RESUMEN

The selective control of O-H/O-D bond dissociation in reduced dimensionality model of HOD molecule has been explored through IR+UV femtosecond pulses. The IR pulse has been optimized using simulated annealing stochastic approach to maximize population of a desired low quanta vibrational state. Since those vibrational wavefunctions of the ground electronic states are preferentially localized either along the O-H or O-D mode, the femtosecond UV pulse is used only to transfer vibrationally excited molecule to the repulsive upper surface to cleave specific bond, O-H or O-D. While transferring from the ground electronic state to the repulsive one, the optimization of the UV pulse is not necessarily required except specific case. The results so obtained are analyzed with respect to time integrated flux along with contours of time evolution of probability density on excited potential energy surface. After preferential excitation from [line]0, 0> ([line]m, n> stands for the state having m and n quanta of excitations in O-H and O-D mode, respectively) vibrational level of the ground electronic state to its specific low quanta vibrational state ([line]1, 0> or [line]0, 1> or [line]2, 0> or [line]0, 2>) by using optimized IR pulse, the dissociation of O-D or O-H bond through the excited potential energy surface by UV laser pulse appears quite high namely, 88% (O-H ; [line]1, 0>) or 58% (O-D ; [line]0, 1>) or 85% (O-H ; [line]2, 0>) or 59% (O-D ; [line]0, 2>). Such selectivity of the bond breaking by UV pulse (if required, optimized) together with optimized IR one is encouraging compared to the normal pulses.

18.
J Chem Phys ; 136(8): 084306, 2012 Feb 28.
Artículo en Inglés | MEDLINE | ID: mdl-22380041

RESUMEN

We perform four-dimensional (4D⊗2D) as well as six-dimensional (6D) quantum dynamics on a parametrically time- and temperature-dependent effective Hamiltonian for D(2)(v, j)-Cu(111) system, where such effective potential has been derived through a mean-field approach between molecular degrees of freedom and surface modes with Bose-Einstein probability factor for their initial state distribution. We present the convergence of the theoretically calculated sticking probabilities employing 4D⊗2D quantum dynamics with increasing number of surface atoms as well as layers for rigid surface and the surface at a particular temperature, where the temperature-dependent sticking probabilities appear exclusively dictated by those surface modes directed along the Z-axis. The sticking and state-to-state transition probabilities obtained from 6D quantum dynamics are shown as a function of initial kinetic energy of the diatom at different surface temperature. Theoretically calculated sticking probabilities display the similar trend with the experimentally measured one.

19.
J Chem Phys ; 136(5): 054104, 2012 Feb 07.
Artículo en Inglés | MEDLINE | ID: mdl-22320722

RESUMEN

We follow a suggestion by Lipoff and Herschbach [Mol. Phys. 108, 1133 (2010)] and compare dressed and bare adiabatic potentials to get insight regarding the low-energy dynamics (e.g., cold reaction) taking place in molecular systems. In this particular case, we are interested to study the effect of conical intersections (ci) on the interacting atoms. For this purpose, we consider vibrational dressed adiabatic and vibrational dressed diabatic potentials in the entrance channel of reactive systems. According to our study, the most one should expect, in case of F + H(2), is a mild effect of the (1, 2) ci on its reactive/exchange process--an outcome also supported by experiment. This happens although the corresponding dressed and bare potential barriers (and the corresponding van der Waals potential wells) differ significantly from each other.

20.
J Phys Chem A ; 115(21): 5256-73, 2011 Jun 02.
Artículo en Inglés | MEDLINE | ID: mdl-21545164

RESUMEN

We include the phonon modes originating from the three layers of Cu(100)/Cu(111) surface atoms on the dynamics of molecular [H(2)(v,j)/D(2)(v,j)] degrees of freedom (DOFs) through a mean field approach, where the surface temperature is incorporated into the effective Hamiltonian (potential) either by considering Boltzmann probability (BP) or by including the Bose-Einstein probability (BEP) factor for the initial state distribution of the surface modes. The formulation of effective potential has been carried out by invoking the expression of transition probabilities for phonon modes known from the "stochastic" treatment of linearly forced harmonic oscillator (LFHO). We perform four-dimensional (4D⊗2D) as well as six-dimensional (6D) quantum dynamics on a parametrically time and temperature-dependent effective Hamiltonian to calculate elastic/inelastic scattering cross-section of the scattered molecule for the H(2)(v,j)-Cu(100) system, and dissociative chemisorption-physisorption for both H(2)(v,j)-Cu(100) and D(2)(v,j)-Cu(111) systems. Calculated sticking probabilities by either 4D⊗2D or 6D quantum dynamics on an effective potential constructed by using BP factor for the initial state distribution of the phonon modes could not show any surface temperature dependence. In the BEP case, (a) both 4D⊗2D and 6D quantum dynamics demonstrate that the phonon modes of the Cu(100) surface affect the state-to-state transition probabilities of the scattered H(2) molecule substantially, and (b) the sticking probabilities due to the collision of H(2) on Cu(100) and D(2) on Cu(111) surfaces show noticeable and substantial change, respectively, as function of surface temperature only when the quantum dynamics of all six molecular DOFs are treated in a fully correlated manner (6D).

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