Journal articles: 'Reaction path finding'

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Galván, Ignacio Fdez, and Martin J. Field. "Improving the efficiency of the NEB reaction path finding algorithm." Journal of Computational Chemistry 29, no. 1 (2007): 139–43. http://dx.doi.org/10.1002/jcc.20780.

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Burger, Steven K., and Paul W. Ayers. "Dual Grid Methods for Finding the Reaction Path on Reduced Potential Energy Surfaces." Journal of Chemical Theory and Computation 6, no. 5 (March 30, 2010): 1490–97. http://dx.doi.org/10.1021/ct100012y.

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Jafari, Mina, and Paul M. Zimmerman. "Reliable and efficient reaction path and transition state finding for surface reactions with the growing string method." Journal of Computational Chemistry 38, no. 10 (January 28, 2017): 645–58. http://dx.doi.org/10.1002/jcc.24720.

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Schaefer, Bastian, Stephan Mohr, Maximilian Amsler, and Stefan Goedecker. "Minima hopping guided path search: An efficient method for finding complex chemical reaction pathways." Journal of Chemical Physics 140, no. 21 (June 7, 2014): 214102. http://dx.doi.org/10.1063/1.4878944.

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De Cos-Cholula, Hector Eduardo, Gerardo Ulises Diaz-Arango, Luis Hernandez-Martinez, Hector Vazquez-Leal, Arturo Sarmiento-Reyes, Maria Teresa Sanz-Pascual, Agustin Leobardo Herrera-May, and Roberto Castaneda-Sheissa. "FPGA Implementation of Homotopic Path Planning Method with Automatic Assignment of Repulsion Parameter." Energies 13, no. 10 (May 21, 2020): 2623. http://dx.doi.org/10.3390/en13102623.

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In recent times, autonomous robots have become more relevant, aiming not only to be an extension of mobility and human performance but also allowing them to independently solve specific problems such as finding free-collision paths within some defined environments. In order to achieve this, several techniques have been developed, like action-reaction algorithms, sampling-based algorithms, and deterministic algorithms such as the Homotopy Path Planning Method (HPPM). This work presents, for the first time, a complete deterministic collision-free path planning scheme implemented in FPGA, which is mounted on a Scribbler 2 robot from Parallax. Then, an automatic algorithm of the repulsion parameter for the HPPM method is presented, using as a reference the minimum distance between the center of each obstacle with respect to the homotopic ideal path; furthermore, an algorithm is proposed for discriminating dead-end routes and collision risk trajectories, which allows us to obtain a feasible free-collision path that takes into account the robot dimensions. Besides, comparative performance tests have been carried out against other path-finding methods from the low degrees of freedom (low DoF) and sampling-based planners. Our proposal exhibits path calculation times which are 5 to 10 times faster on FPGA implementation, compared to the other methods and 10 to 100 times faster on PC implementation also compared to the rest. Similar results are obtained with regards to memory consumption, namely 20 to 200 times lower on FPGA implementation and 10 to 100 times lower on PC implementation.

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Sugimura, Natsuhiko, Yoko Igarashi, Reiko Aoyama, and Toshimichi Shibue. "Nudged elastic band method and density functional theory calculation for finding a local minimum energy pathway of p-benzoquinone and phenol fragmentation in mass spectrometry." European Journal of Mass Spectrometry 23, no. 1 (February 2017): 40–44. http://dx.doi.org/10.1177/1469066716688412.

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Analysis of the fragmentation pathways of molecules in mass spectrometry gives a fundamental insight into gas-phase ion chemistry. However, the conventional intrinsic reaction coordinates method requires knowledge of the transition states of ion structures in the fragmentation pathways. Herein, we use the nudged elastic band method, using only the initial and final state ion structures in the fragmentation pathways, and report the advantages and limitations of the method. We found a minimum energy path of p-benzoquinone ion fragmentation with two saddle points and one intermediate structure. The primary energy barrier, which corresponded to the cleavage of the C–C bond adjacent to the CO group, was calculated to be 1.50 eV. An additional energy barrier, which corresponded to the cleavage of the CO group, was calculated to be 0.68 eV. We also found an energy barrier of 3.00 eV, which was the rate determining step of the keto-enol tautomerization in CO elimination from the molecular ion of phenol. The nudged elastic band method allowed the determination of a minimum energy path using only the initial and final state ion structures in the fragmentation pathways, and it provided faster than the conventional intrinsic reaction coordinates method. In addition, this method was found to be effective in the analysis of the charge structures of the molecules during the fragmentation in mass spectrometry.

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QUAPP, WOLFGANG. "THE GROWING STRING METHOD FOR FLOWS OF NEWTON TRAJECTORIES BY A SECOND-ORDER METHOD." Journal of Theoretical and Computational Chemistry 08, no. 01 (February 2009): 101–17. http://dx.doi.org/10.1142/s0219633609004575.

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The reaction path is an important concept of theoretical chemistry. We use a definition with a reduced gradient (see Quapp et al., Theor Chem Acc100:285, 1998), also named Newton trajectory (NT). To follow a reaction path, we design a numerical scheme for a method for finding a transition state between reactant and product on the potential energy surface: the growing string (GS) method. We extend the method (see W. Quapp, J Chem Phys122:174106, 2005) by a second-order scheme for the corrector step, which includes the use of the Hessian matrix. A dramatic performance enhancement for the exactness to follow the NTs, and a dramatic reduction of the number of corrector steps are to report. Hence, we can calculate flows of NTs. The method works in nonredundant internal coordinates. The corresponding metric to work with is curvilinear. The GS calculation is interfaced with the GamessUS package (we have provided this algorithm on ). Examples for applications are the HCN isomerization pathway and NTs for the isomerization C7ax ↔ C5 of alanine dipeptide.

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Gouran, Ali Asghar, and Sakineh Asghari. "On Searching for a Stepwise Channel for the Mechanism of a 1,3-Dipolar Cycloaddition between a Thiocarbonyl S-Oxide and C20 Fullerene using Born–Oppenheimer ab Initio QM/MM Molecular Dynamics." Progress in Reaction Kinetics and Mechanism 42, no. 3 (September 2017): 282–88. http://dx.doi.org/10.3184/146867817x14954764850315.

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The probability of existence of a stepwise route which is in parallel with the well-known concerted pathway for the mechanism of 1,3-dipolar cycloaddition is debated by many researchers. As the route is stepwise, it would lead to emergence of at least a metastable intermediate which would produce some stereoisomers such as enantiomers and diastereomers. In 1986 the first clear stepwise example for a 1,3-dipolar cycloaddition was reported by Huisgen where an electron-poor alkene was reacted with a thiocarbonyl ylide. Since then, researchers have focused on the thiocarbonyl ylide 1,3-dipolar group in finding more stepwise examples. It was found that some reactions of a thiocarbonyl ylide with some dipolarophiles proceeded by a stepwise route, while others did not. This situation led us to investigate the probability of existence a stepwise route in parallel with the concerted path for the reaction of methyl thiocarbonyl S-oxide and C20 fullerene as a chemically active and nano-dimension electronegative alkene. To give more reliable data, Born–Oppenheimer ab initio QM/MM molecular dynamics was used.

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Voytek, Emily B., Caitlin R. Rushlow, Sarah E. Godsey, and Kamini Singha. "Identifying hydrologic flowpaths on arctic hillslopes using electrical resistivity and self potential." GEOPHYSICS 81, no. 1 (January 1, 2016): WA225—WA232. http://dx.doi.org/10.1190/geo2015-0172.1.

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Shallow subsurface flow is a dominant process controlling hillslope runoff generation, soil development, and solute reaction and transport. Despite their importance, the location and geometry of these flow paths are difficult to determine. In arctic environments, shallow subsurface flow paths are limited to a thin zone of seasonal thaw above permafrost, which is traditionally assumed to mimic the surface topography. We have used a combined approach of electrical resistivity tomography (ERT) and self-potential (SP) measurements to map shallow subsurface flow paths in and around water tracks, drainage features common to arctic hillslopes. ERT measurements delineate thawed zones in the subsurface that control flow paths, whereas SP is sensitive to groundwater flow. We have found that areas of low electrical resistivity in the water tracks were deeper than manual thaw depth estimates and varied from the surface topography. This finding suggests that traditional techniques might underestimate active-layer thaw and the extent of the flow path network on arctic hillslopes. SP measurements identify complex 3D flow paths in the thawed zone. Our results lay the groundwork for investigations into the seasonal dynamics, hydrologic connectivity, and climate sensitivity of spatially distributed flow path networks on arctic hillslopes.

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Garifzianova, Guzel G. "Theoretical study of the isomerization of 1-amino-4-phenylamino-9,10-anthraquinone." Butlerov Communications 60, no. 12 (December 31, 2019): 37–42. http://dx.doi.org/10.37952/roi-jbc-01/19-60-12-37.

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This paper presents the results of computer simulation of tautomeric transformations of the molecule 1-amino-4-phenylamino-9,10-anthraquinone. It is known from the literature that the presence of substituents in the 1,4-position of anthraquinone-9,10 leads to various tautomeric transformations, with a shift in the absorption maximum and the appearance of absorption bands in the red wave region in electronic spectra. Both the 1-amino-4-hydroxyanthraquinone described in the literature and the 1-amino-4-phenylamino-9,10-anthraquinone are characterized by two types of prototropic tautomerism – keto-enol and amino-imine. Quantum-chemical modeling contributes to the calculation of the relative energies of tautomers and isomers, the barriers of their interconversions, as well as finding their structural parameters. The aim of this study was to study the mechanism of the formation of tautomers during hydrogen transfer in the molecule of 1-amino-4-phenylamino-9,10-anthraquinone, as well as the formation of isomers during migration of the OH group. The calculations were performed using the Gaussian09 program. To study of various tautomers of 1-amino-4-phenylamino-9,10-anthraquinone, the B3LYP method with the def2TZV basis was used. A search was conducted for transition states during hydrogen transfer and OH group migration. The descent along the reaction path was calculated to confirm that the transition state is in the path of the desired reaction. The minima corresponding to the starting material and product were localized. The activation enthalpies of the studied reactions were calculated. Migration of the OH group in the 1-amino-4-phenylamino-9,10-anthraquinone molecule leads to the formation of 4-phenylamino-9-amino-1,10-anthraquinone. As the calculation shows, the keto-form of 1-amino-4-phenylamino-9,10-anthraquinone is energetically more profitable than all the isomers studied in this work, including the enol form. The smallest difference in total potential energies is 23.7 kJ/mol between the initial ketone form of 1-amino-4-phenylamino-9,10-anthraquinone and the last transformation structure – the 4-phenylamino-9-amino-1,10-anthraquinone molecule.

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Räsänen, Markku, Henrik Kunttu, and Juhani Murto. "Infrared Induced Conformer Interconversion Processes in Low-Temperature Matrices." Laser Chemistry 9, no. 1-3 (January 1, 1988): 123–45. http://dx.doi.org/10.1155/lc.9.123.

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Molecules embedded in low-temperature matrices experience conformer interconversion processes due to IR- (or UV-)irradiation. This paper summarizes the known IR-induced conformational changes, of which the majority has been studied by using broad-band sources provided with filters. We focus at the thermal and IR-photochemical methods in obtaining information of conformational energetics of matrix isolated molecules, at the usefulness of ab initio calculations in assigning the spectra of conformers involved and in finding the reaction path on the ground state surface. The data obtained from a number of molecules is used to discuss possible mechanisms in both intramolecularly hydrogen-bonded and non-bonded molecules. Also possible indications of mode-selective phenomena in these processes are dealt with. In addition, common trends found for photorotamerization in different hosts are discussed.

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Wünschel, Markus, Ulf Leichtle, JiaHsuan Lo, Nikolaus Wülker, and Otto Müller. "Differences in tibiofemoral kinematics between the unloaded robotic passive path and a weightbearing knee simulator." Orthopedic Reviews 3, no. 2 (January 3, 2012): 2. http://dx.doi.org/10.4081/or.2012.e2.

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Cadaveric in vitro studies are essential to test hypotheses concerning surgical manipulations in the same individual. Robotic technologies as well as different knee-models have been developed to get an in-depth comprehension of knee joint kinematics. The purpose of this study was to compare utilization of these different established principles. Ten human cadaveric knee specimens were used to measure the kinematics during a weight-bearing flexion in a 6-degrees-of-freedom knee simulator. While flexing the knee, joint quadriceps muscle forces were dynamically simulated to reach a vertical ground reaction force of 100N. Fourteen knee specimens were mounted in 6-degrees-of-freedom robotic manipulator with a universal force sensor. The unloaded flexing motion of each specimen was measured by finding positions for each degree of flexion where all forces are minimal (passive path). The kinematic data of the kneesimulator and the robot concerning internal-external rotation, anterior-posterior translation, varus-valgus motion, and medial-lateral translation was examined. For all investigated degrees of freedom the kinematics of the robotic passive path differed from the loaded kinematics in the knee simulator. Simulated bodyweight as well as the examination method used has a substantial influence on joint kinematics during flexion which has to be considered when interpreting biomechanical studies as well as clinical tests.

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Dattoli, Michael J., Stephen M. Bravo, Daniel Kaplon, Matt Hayes, Alexandria Osorio, Patricia M. Dycus, David G. Bostwick, and Joseph Kaminski. "Efficacy of ferumoxytol as a lymphatic contrast agent in prostate cancer." Journal of Clinical Oncology 36, no. 6_suppl (February 20, 2018): 186. http://dx.doi.org/10.1200/jco.2018.36.6_suppl.186.

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186 Background: Ferumoxytol (Feraheme) is a ferromagnetic nanoparticle with lymphotrophic biokinetics, delivered to lymph nodes by normal macrophages. MRI suppresses normal lymph nodes containing Feraheme. Objective is to validate safety and efficacy in finding lymph node positivity in prostate cancer (PCa). Methods: Nonrandomized prospective evaluation of 178 consecutive PCa patients (pts) at high risk for lymph node spread enrolled 2/13-3/15. All received IV Feraheme. 177 received 6/mg/kg over 20 min. One pt received 3 mg/kg infusion. T2 MEDIC and T2* sequence imaging of abdomen and pelvis, given 24 hours later. Images reviewed by 2 board certified radiologists with same interpretations, blinded to clinical and histo-path info (pre-MRI TNM stage/PSA/Gleason). Nodes were deemed abnormal if they did not suppress after Feraheme infusion (group 1, 94 patients). Nodes were deemed suspicious if suppressed and met usual size criteria with high signal intensity on DWI and decreased ADC map values and morphologic features (group 2, 84 pts). 83 group 1 pts had CT biopsies (77 pelvis, 6 retroperitoneum);11 pts had open PLND. 382 lymph nodes sampled. 76 group 2 patients had CT biopsies (73 pelvis, 3 retroperitoneum); 9 pts had open PLND. 340 lymph nodes sampled. Rad-path correlation was performed. Nodes were stained; reviewed by a single pathologist with no knowledge of MRI findings. Histo-path results for each node were cataloged for later MRI comparison. Results: 90 group 1 pts (96%) proved metastatic PCa; 4 pts (4%) were normal. 68 group 1 pts (77%) had malignant lymph nodes not meeting usual imaging criteria. 39 group 2 pts (47%) showed metastatic PCa; 46 pts (53%) were normal. One group 2 pt had an allergic reaction with hives; infusion ceased at 3mg/kg; pt treated to full resolution with 50 mg IV Benadryl. Conclusions: Feraheme can evaluate lymphatic dissemination of metastatic disease in PCa patients, with a lower limit of resolution of focal lymph node metastases of 2-3 mm. Better resolution gives implications for therapeutic radiation planning of newly diagnosed or recurrent/metastatic PCa. Toxicity was very acceptable at 6mg/kg. Feraheme may play a significant role as a lymphatic contrast agent in the early dissemination of lymphatic metastatic disease.

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Hsieh, Chih-Hsiang, Wei-Kuan Wang, Cheng-Xun Wang, Shi-Chun Tsai, and Yi-Bing Lin. "Efficient Detection of Link-Flooding Attacks with Deep Learning." Sustainability 13, no. 22 (November 12, 2021): 12514. http://dx.doi.org/10.3390/su132212514.

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The DDoS attack is one of the most notorious attacks, and the severe impact of the DDoS attack on GitHub in 2018 raises the importance of designing effective defense methods for detecting this type of attack. Unlike the traditional network architecture that takes too long to cope with DDoS attacks, we focus on link-flooding attacks that do not directly attack the target. An effective defense mechanism is crucial since as long as a link-flooding attack is undetected, it will cause problems over the Internet. With the flexibility of software-defined networking, we design a novel framework and implement our ideas with a deep learning approach to improve the performance of the previous work. Through rerouting techniques and monitoring network traffic, our system can detect a malicious attack from the adversary. A CNN architecture is combined to assist in finding an appropriate rerouting path that can shorten the reaction time for detecting DDoS attacks. Therefore, the proposed method can efficiently distinguish the difference between benign traffic and malicious traffic and prevent attackers from carrying out link-flooding attacks through bots.

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Tiwary, Pratyush, and B. J. Berne. "Spectral gap optimization of order parameters for sampling complex molecular systems." Proceedings of the National Academy of Sciences 113, no. 11 (February 29, 2016): 2839–44. http://dx.doi.org/10.1073/pnas.1600917113.

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In modern-day simulations of many-body systems, much of the computational complexity is shifted to the identification of slowly changing molecular order parameters called collective variables (CVs) or reaction coordinates. A vast array of enhanced-sampling methods are based on the identification and biasing of these low-dimensional order parameters, whose fluctuations are important in driving rare events of interest. Here, we describe a new algorithm for finding optimal low-dimensional CVs for use in enhanced-sampling biasing methods like umbrella sampling, metadynamics, and related methods, when limited prior static and dynamic information is known about the system, and a much larger set of candidate CVs is specified. The algorithm involves estimating the best combination of these candidate CVs, as quantified by a maximum path entropy estimate of the spectral gap for dynamics viewed as a function of that CV. The algorithm is called spectral gap optimization of order parameters (SGOOP). Through multiple practical examples, we show how this postprocessing procedure can lead to optimization of CV and several orders of magnitude improvement in the convergence of the free energy calculated through metadynamics, essentially giving the ability to extract useful information even from unsuccessful metadynamics runs.

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Thirunavukarasu, Gopinath, Sukumar Kundu, Vivek V. Patel, and Alankar Alankar. "Analytical Investigation on the Evolution and Growth of β-Ti and Fe-Nb-Based Intermetallics in Diffusion Coupled Joints of Ti6Al4V|Nb|SS." Diffusion Foundations 27 (May 2020): 3–24. http://dx.doi.org/10.4028/www.scientific.net/df.27.3.

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Herein, solid-state diffusion-coupled joints (DCJs) were prepared in vacuum between stainless steel (SS) and Ti6Al4V by means of a pure niobium (Nb) interlayer (~200-μm thickness) using uni-axial compressive pressure of 4 MPa at 875 °C for 15 to 120 min. Interfacial characterization revealed the existence of successive layer wise Fe–Nb-based intermetallics like FeNb+(Nb) and Fe2Nb at Nb|SS interfaces of DCJs processed from 60 to 120 min, but the DCJs processed for shorter duration (from 15 to 30 min) do not reveal any intermetallics; however, the DCJs processed for 45 min revealed a single reaction layer of FeNb whereas that of Ti6Al4V|Nb interfaces revealed solid solution behaviour for all bonding time intervals. Required chemical analysis (in at. pct) of the reaction products was found out using spectroscope and X-ray diffractometer. Mechanical characterization (at 32 °C) of the DCJs was carried out with a microhardness tester and tensile testing facility. Ti6Al4V|Nb interface experienced a hardness of ~298 HV (for all bonding time), whereas Nb|SS interface experienced ~200 HV for 15 and 30 min and ~650 HV for 45 min and longer. DCJs treated for 60 min have better strength properties. Manifestation of reaction layers: FeNb, FeNb+(Nb), and Fe2Nb have significant effect on the strength. From the interfacial microhardness, path and surface of fracture surfaces characterizations, it was revealed that failure of the DCJs was transmitted seemingly along Nb|SS interfaces. The analytical finding of intrinsic diffusivity of Ti atoms in Nb along Ti6Al4V|Nb interface is higher by one order of magnitude than the diffusivity results of Fe atoms in Nb along the Nb|SS interface. Experimental evidences show that the growth of the reaction products along Ti6Al4V|Nb interface (adj. R-Square=0.982) and Nb|SS interface (adj. R-Square=0.999) follows a parabolic law. Recently, researchers considered diffusion coupling as the key technology to fabricate Ti|Al|Al-Cf biomimetic structure, graphite|Nb|Cu for fusion reactor devices, Ni|Ni3Al for MEMS applications, hybrid heat exchangers for nuclear applications, etc.

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Couto, Egle, Ricardo Barini, Renata Zaccaria, Joyce Maria Annicchino-Bizzacchi, Renato Passini Junior, Belmiro Gonçalves Pereira, José Carlos Gama da Silva, and João Luiz Pinto e. Silva. "Association of anticardiolipin antibody and C677T in methylenetetrahydrofolate reductase mutation in women with recurrent spontaneous abortions: a new path to thrombophilia?" Sao Paulo Medical Journal 123, no. 1 (January 2005): 15–20. http://dx.doi.org/10.1590/s1516-31802005000100004.

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CONTEXT: Recurrent spontaneous abortion (RSA) has been associated with venous thrombosis in the mother. Acquired and inherited thrombophilia factors are possible causes. OBJECTIVE: To evaluate the association between thrombogenic factors and recurrent spontaneous abortion. TYPE OF STUDY: Case-control study. SETTING: Centro de Atenção Integral à Saúde da Mulher, Universidade Estadual de Campinas. METHODS: 40 ml of blood was collected from 88 women attending an RSA clinic and 88 fertile women attending a family planning clinic, to evaluate the presence of acquired and inherited thrombophilia factors. Anticardiolipin antibodies (ACA), lupus anticoagulant and deficiencies of proteins C and S and antithrombin III were evaluated by enzyme-linked immunosorbent assay (ELISA), dilute Russell Viper Venom time (dRVVT), coagulometric and chromogenic methods. DNA was amplified by the polymerase chain reaction (PCR) to study factor V Leiden and G20210A mutations in the prothrombin gene and C677T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene. Data were analyzed using odds ratios and a regression model for age adjustment. Fisher’s exact test was used to evaluate statistical relationships between associated factors and RSA. RESULTS: ACA was detected in 11 women with RSA and one fertile woman. Heterozygous C677T was detected in 59 women with RSA and 35 fertile women. Concomitant presence of ACA and C677T was found in eight women with RSA and no fertile women (p < 0.01). DISCUSSION: The meaning of the association between C677T mutation in the MTHFR gene and ACA is still not clear. It is possible that an inherited factor that alone would not strongly predispose a woman to thrombosis could, when associated with an acquired factor, start the process and increase the likelihood of thrombosis expression. CONCLUSIONS: ACA and C677T in the MTHFR gene are statistically associated with RSA. The association of these two conditions is a new finding in thrombogenic factors and RSA.

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Malik, Chirag, and Sonali Yadav. "Sustainability ratings and corporate control: Debacle of shareholder over stakeholder theory." Corporate Ownership and Control 18, no. 1, Special Issue (2020): 408–22. http://dx.doi.org/10.22495/cocv18i1siart14.

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Corporate sustainability rating is frequently observed by different stakeholders, thereby finding interest in academic studies as well. Shareholders of sustainable-companies respond to different types of stock market news, be it financial or non-financial news. Announcements relating to ratings obtained by sustainability-compliant businesses appear to create anticipation in the mind of the investor. If these announcements are viewed by investors with interest, then it can have a greater implication for corporate governance and control and the corporate leaders can find a clear path to resolve the much debated “shareholder” versus “stakeholder” view in decision-making. This paper aims to explain whether or not the declaration of sustainability ratings contributes to the stock market reaction in emerging markets such as India. Short-run event analysis was carried out on a set of selected BSE listed companies following sustainable practice (2017-2019) and the entire data set was split into categories of the upgrade, downgrade, no change, and no ratings. The study results show that the announcement of sustainability ratings is not regarded by investors with a great deal of interest and there is inherent indifference to such news in the stock market. These findings are relevant for stock exchanges, investors, and corporate control as it raises a serious issue of rethinking stakeholder awareness levels, which in an emerging economy such as India currently seem to be in a nascent stage. In order to meet the stakeholders interested in the process of business becoming sustainable corporate leaders through proper governance should explore ways and means to approach sustainability in a more systematic way

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Chang, Hsin-An, Wen-Hui Fang, Yia-Ping Liu, Nian-Sheng Tzeng, Jia-Fwu Shyu, Fang-Jung Wan, San-Yuan Huang, Tieh-Ching Chang, and Chuan-Chia Chang. "Sex-specific pathways among tri-allelic serotonin transporter polymorphism, trait neuroticism and generalized anxiety disorder." Journal of Psychiatry & Neuroscience 45, no. 6 (November 1, 2020): 379–86. http://dx.doi.org/10.1503/jpn.190092.

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Background: Neuroticism personality trait is recognized as an important endophenotypic predictor of generalized anxiety disorder (GAD). Furthermore, endophenotype-based pathway approaches have recently been shown to have greater advantages for gene-finding strategies than traditional case–control studies. In the present study, in addition to conventional case–control methods, we used pathway analyses to test whether the tri-allelic serotonin transporter promoter polymorphism (combining 5-HTTLPR and rs25531) is associated with risk of GAD through its effects on trait neuroticism. Methods: We included 2236 Han Chinese adults in this study, including 736 patients with GAD and 1500 healthy participants. We genotyped the 5-HTTLPR and rs25531 polymorphisms using the polymerase chain reaction restriction fragment length polymorphism method. We used the Neuroticism scale of the Maudsley Personality Inventory (MPI) short version (MPI-Neuroticism) to measure participants’ tendency toward neuroticism. Results: Using endophenotype-based path analyses, we found significant indirect effects of the tri-allelic genotype on risk of GAD, mediated by MPI-Neuroticism in both men and women. Compared to women carrying the S’S’ genotype, women carrying the L‘ allele had higher levels of MPI-Neuroticism, which in turn were associated with higher risk of GAD. Men, however, showed the opposite pattern. Using traditional case–control comparisons, we observed that the effect of tri-allelic genotype on GAD was significant, but only in women. Limitations: Participants were restricted to Han Chinese, and we used only 1 questionnaire to assess neuroticism. Conclusion: These findings are the first to show that the tri-allelic 5-HTTLPR polymorphism is associated with elevated risk of GAD, and that this effect is mediated via increased trait neuroticism, a sex-dependent risk pathway.

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Aguilar-Mogas, Antoni, Xavier Giménez, and Josep Maria Bofill. "Finding reaction paths using the potential energy as reaction coordinate." Journal of Chemical Physics 128, no. 10 (March 14, 2008): 104102. http://dx.doi.org/10.1063/1.2834930.

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Ejaz, Mehak, and Kalim Hyder. "Fan Chart Approach to Debt Sustainability in Pakistan." LAHORE JOURNAL OF ECONOMICS 24, no. 2 (July 1, 2019): 1–23. http://dx.doi.org/10.35536/lje.2019.v24.i2.a1.

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Pakistan’s economy has experienced relatively high growth of above 4.5 percent during FY2014-18. Meanwhile external liabilities and domestic debt have increased by almost 50 percent over the same period. This substantial increase in the external and domestic debt is a major issue for policymakers concerned about debt sustainability in Pakistan. With the objective of analyzing debt sustainability in Pakistan, this study applies a probabilistic approach to project the debt path from FY2019 to FY2025. In this approach, projections of the primary balance are derived from the estimated fiscal reaction function while the density forecast of external debt is derived from various statistical and structural models. The forecasts of the primary balance and the external debt along with the shocks of real GDP growth, real exchange rate and real interest are incorporated in the debt accumulation identity. This procedure provides a fan chart of the total debt-to-GDP ratio, which represents the appropriate uncertainty associated with the projections. The key finding of the paper is that external debt is reasonably sustained; however, the situation of the total debt is alarming. External debt may witness a declining trajectory in FY2019-20 and then remain stable within the range of 20-30 percent of GDP. However, the total debt-to-GDP ratio is rising throughout the projection period, which starts from around 100 to 175 percent of GDP in FY2020 and FY2025 and is higher than any sustainable threshold level. Therefore, policy makers need to contain fiscal deficits by domestic resource mobilization and the adoption of austerity in spending on a priority basis.

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Kale, Seyit, Olaseni Sode, Jonathan Weare, and Aaron R. Dinner. "Finding Chemical Reaction Paths with a Multilevel Preconditioning Protocol." Journal of Chemical Theory and Computation 10, no. 12 (November 21, 2014): 5467–75. http://dx.doi.org/10.1021/ct500852y.

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Rambidi, N. G., and D. Yakovenchuck. "Finding paths in a labyrinth based on reaction–diffusion media." Biosystems 51, no. 2 (August 1999): 67–72. http://dx.doi.org/10.1016/s0303-2647(99)00022-2.

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Fournier, René, Satya Bulusu, Stephen Chen, and Jamie Tung. "Using swarm intelligence for finding transition states and reaction paths." Journal of Chemical Physics 135, no. 10 (September 14, 2011): 104117. http://dx.doi.org/10.1063/1.3633515.

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Isamura, Bienfait Kabuyaya, and Kevin Alan Lobb. "New Insights into the (A)Synchronicity of Diels–Alder Reactions: A Theoretical Study Based on the Reaction Force Analysis and Atomic Resolution of Energy Derivatives." Molecules 27, no. 5 (February 25, 2022): 1546. http://dx.doi.org/10.3390/molecules27051546.

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In the present manuscript, we report new insights into the concept of (a)synchronicity in Diels–Alder (DA) reactions in the framework of the reaction force analysis in conjunction with natural population calculations and the atomic resolution of energy derivatives along the intrinsic reaction coordinate (IRC) path. Our findings suggest that the DA reaction transitions from a preferentially concerted mechanism to a stepwise one in a 0.10 Å window of synchronicity indices ranging from 0.90 to 1.00 Å. We have also shown that the relative position of the global minimum of the reaction force constant with respect to the TS is an alternative and quantifiable indicator of the (a)synchronicity in DA reactions. Moreover, the atomic resolution of energy derivatives reveals that the mechanism of the DA reaction involves two inner elementary processes associated with the formation of each of the two C-C bonds. This resolution goes on to indicate that, in asynchronous reactions, the driving and retarding components of the reaction force are mostly due to the fast and slow-forming C-C bonds (elementary processes) respectively, while in synchronous reactions, both elementary processes retard and drive the process concomitantly and equivalently.

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Nikolic, Marin, Luke Daemen, Anibal J. Ramirez-Cuesta, Rafael Balderas Xicohtencatl, Yongqiang Cheng, Seth T. Putnam, Nicholas P. Stadie, Xiaochun Liu, Jasmin Terreni, and Andreas Borgschulte. "Neutron Insights into Sorption Enhanced Methanol Catalysis." Topics in Catalysis 64, no. 9-12 (June 6, 2021): 638–43. http://dx.doi.org/10.1007/s11244-021-01461-w.

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AbstractSorption enhanced methanol production makes use of the equilibrium shift of the $$\hbox {CO}_2$$ CO 2 hydrogenation reaction towards the desired products. However, the increased complexity of the catalyst system leads to additional reactions and thus side products such as dimethyl ether, and complicates the analysis of the reaction mechanism. On the other hand, the unusually high concentration of intermediates and products in the sorbent facilitates the use of inelastic neutron scattering (INS) spectroscopy. Despite being a post-mortem method, the INS data revealed the change of the reaction path during sorption catalysis. Concretely, the experiments indicate that the varying water partial pressure due to the adsorption saturation of the zeolite sorbent influences the progress of the reaction steps in which water is involved. Experiments with model catalysts support the INS findings.

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Yang, Yul W., Collin M. Costello, and Aaron R. Mangold. "Dermoscopic Findings of Irritant “Poral” Reactions to Cobalt During Patch Testing." Dermatitis 28, no. 6 (2017): 367. http://dx.doi.org/10.1097/der.0000000000000322.

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Celani, Paolo, Michael A. Robb, Marco Garavelli, Fernando Bernardi, and Massimo Olivucci. "Geometry optimisation on a hypersphere. Application to finding reaction paths from a conical intersection." Chemical Physics Letters 243, no. 1-2 (September 1995): 1–8. http://dx.doi.org/10.1016/0009-2614(95)00821-k.

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Banerjee, Subham, Pronobesh Chattopadhyay, Animesh Ghosh, Manash Pratim Pathak, Shweta Singh, and Vijay Veer. "Acute Dermal Irritation, Sensitization, and Acute Toxicity Studies of a Transdermal Patch for Prophylaxis Against (±) Anatoxin-A Poisoning." International Journal of Toxicology 32, no. 4 (May 21, 2013): 308–13. http://dx.doi.org/10.1177/1091581813489996.

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The skin irritating, sensitizing, and acute dermal toxicity potential of a novel combinational prophylactic transdermal patch, mainly composed of eserine and pralidoxime chloride as active pharmaceutical ingredients, against (±) anatoxin-a poisoning were investigated in rabbits, guinea pigs, and rats in compliance with the Organisation for Economic Cooperation and Development guidelines. In primary skin irritation test, rabbits were dermally attached with the therapeutically active transdermal patch or with a placebo patch for 72 hours. The transdermal patches did not induce any adverse reactions such as erythema and edema on intact skin sites. The active patch was classified as a practically nonirritating material based on the score in the primary irritation index. In the Buehler test, guinea pigs were sensitized by the active or placebo transdermal patches attached for 24 hours. The patches did not induce any sensitization reactions in contrast to a severe sensitization reaction that occurred in the positive control. Therefore, the active patch and placebo patch were both graded as weak in sensitization score and rate. Acute dermal toxicity test in rats did not produce any overt signs of toxicity following a 14-day treatment period. Taken together, these findings suggest that the transdermal patch does not cause skin irritation, skin sensitization, or dermal toxic effects following dermal application.

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Rambidi, N. G., and D. Yakovenchuk. "Information-processing capabilities of chemical reaction-diffusion systems. 2: Finding paths in a labyrinth based on reaction-diffusion media." Advanced Materials for Optics and Electronics 9, no. 1 (January 1999): 27–34. http://dx.doi.org/10.1002/(sici)1099-0712(199901/02)9:1<27::aid-amo363>3.0.co;2-e.

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Teymoortash, A., J. A. Fasunla, W. Pfützner, and S. Steinbach-Hundt. "Nasal tip abscess due to adverse skin reaction to Prolene: an unusual long term complication of rhinoplasty." Journal of Laryngology & Otology 127, no. 1 (November 22, 2012): 76–79. http://dx.doi.org/10.1017/s0022215112002575.

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AbstractObjectives:Allergic reactions to Prolene are rare. This paper reports a nasal tip abscess which developed in a patient with an adverse skin reaction to Prolene after rhinoplasty.Methods and results:A 26-year-old woman presented with painful, progressive nasal tip swelling and redness. She had undergone septo-rhinoplasty two years previously. She was initially treated with endonasal drainage of the abscess and antibiotics, but a revision rhinoplasty three months later became necessary because of recurrent abscess formation. Intra-operative findings included granulation tissue with pockets of pus and knotted Prolene sutures at the tip-defining points of the lower lateral cartilages. She was patch-tested with Prolene and a cutaneous Prolene suture was placed on her back; an adverse skin reaction was seen for the latter.Conclusion:Use of non-absorbable sutures, such as Prolene, in the subcutaneous layer may be a potential, rare risk factor for adverse skin reactions.

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Charenton, Clément, and Marc Graille. "mRNA decapping: finding the right structures." Philosophical Transactions of the Royal Society B: Biological Sciences 373, no. 1762 (November 5, 2018): 20180164. http://dx.doi.org/10.1098/rstb.2018.0164.

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In eukaryotes, the elimination of the m 7 GpppN mRNA cap, a process known as decapping, is a critical, largely irreversible and highly regulated step of mRNA decay that withdraws the targeted mRNAs from the pool of translatable templates. The decapping reaction is catalysed by a multi-protein complex formed by the Dcp2 catalytic subunit and its Dcp1 cofactor, a holoenzyme that is poorly active on its own and needs several accessory proteins (Lsm1–7 complex, Pat1, Edc1–2, Edc3 and/or EDC4) to be fully efficient. Here, we discuss the several crystal structures of Dcp2 domains bound to various partners (proteins or small molecules) determined in the last couple of years that have considerably improved our current understanding of how Dcp2, assisted by its various activators, is recruited to its mRNA targets and adopts its active conformation upon substrate recognition. We also describe how, over the years, elegant integrative structural biology approaches combined to biochemistry and genetics led to the identification of the correct structure of the active Dcp1–Dcp2 holoenzyme among the many available conformations trapped by X-ray crystallography. This article is part of the theme issue ‘5′ and 3′ modifications controlling RNA degradation’.

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Judajana, F. M., Paulus Budiono, and Indah Nuraini. "ANALISIS POLA HUMAN LEKOCYTE ANTIGEN (HLA) KELAS I PADA PENDERITA DEMAM BERDARAH DENGUE POPULASI INDONESIA DI JAWA TIMUR." INDONESIAN JOURNAL OF CLINICAL PATHOLOGY AND MEDICAL LABORATORY 18, no. 2 (March 17, 2018): 105. http://dx.doi.org/10.24293/ijcpml.v18i2.1008.

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The incidence of Dengue Haemorrhagic Fever (DHF) is obvious rapidly increasing and it may have existed previously, and specificfactors precipitating of the diseases can be identified in Indonesia population. These include environmental changes, demographic factors,host immunity, micro organism variant and drug resistance suggesting that infection will continue to emerge, probably increase andemphasizes the urgent need for effective surveillance. The Immunology approach of Dengue Haemorrhagic Fever as emerging diseaseshas been advanced on two major fronts. First, the elucidation of the basic mechanisms associated antigen recognition, elimination,rejection and immunological protection from recurrence. Secondly, to solve the clinical problem (diagnostic, therapeutic and prevention)the application of the knowledge of immunological memory to diseases is used as a tool. Over expressed emerging pathogens such asmolecularly defined mutated antigen; this antigen as a target of specific immune reaction and has been encountered as a danger signal.The current studies have shown that few immune competent cells (activated T cells and B cells) are exposed to antigen. The immuneconsequence of infectious tissue induced Major Histocompatibility Complex (MHC)/Human Leukocyte Antigen (HLA) molecules expressionon antigen presenting cell and have also shown, that an immunological reaction occurs in all organs in response to a number of diseases.However, most infectious diseases express MHC/HLA class II molecules, in order to recognize the new mutated antigen and also expressthe MHC/HLA class I molecules in order to eliminate those antigen. Progress in the genetic dissection of infectious diseases will also comefrom the complementary analysis of the various biological and clinical phenotypes associated with a given infectious agent, stronglysuggesting that host factors play an important role in susceptibility or resistance to infection. In order to know the regulation processbetween different types of pathogen and the host immune system, as well as the regulation factor of the cross talk between the differentcomponents of the immune response in human as the host, it is important to get an understanding of the immune genetic system. Thisresearch work is aimed at the locating and identifying the HLA class I which encode the protein as immune-component to be involvedin the pathogenesis of DHF as a viral infection base on the examination on 20 DHF patients and have already examined the HLA-A, -Bas HLA class I with the DNA typing-PCR. The results analysis with Chi square with Yates‘s Correction and the relative risk (Wolf rule)is HLA-A*11,-A*24 and HLA-B*15,-B*18 has specific association with DHF on Indonesia population in East Java. The evidence of theinfluence of the immune genetics marker to the DHF is provided by the following observations: (1) the level of infection often differsgreatly among infected subjects, (2) some infected subjects do not develop clinical disease, (3) the clinical manifestations of diseaseseverity, time to onset, duration of disease etc, may differ greatly among symptomatic patients. This finding opens the path to developeffective means of immunotherapy and improved the diagnosis for lesions, in order to apply the current strategies for the developing ofimmunodiagnostic, immunotherapy-based treatment through an infected target cell or developed new effective vaccines.

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PIERROUTSAKOU, DIMITRA. "DYNAMICAL DIPOLE MODE IN FUSION HEAVY-ION REACTIONS." International Journal of Modern Physics E 19, no. 05n06 (June 2010): 1031–42. http://dx.doi.org/10.1142/s0218301310015473.

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The prompt γ-ray emission, associated with the dynamical dipole mode decay, was investigated in the 32,36 S + 100,96 Mo and 36,40 Ar + 96,92 Zr fusion-evaporation reactions in the energy range E lab= 6 - 16 MeV / nucleon . The above reaction pairs populate, through entrance channels having different charge asymmetries, a compound nucleus in the 132 Ce mass region at excitation energies of 117, 174 and 284 MeV with identical spin distribution. By studying the differential γ-ray multiplicity spectra of the considered systems, the features of the dynamical dipole mode as a function of the beam energy were extracted while the γ-ray angular distributions were used to prove its pre-equilibrium character. The experimental findings were compared with theoretical predictions performed within a BNV transport model and based on a collective bremsstrahlung analysis of the entrance channel reaction dynamics. As a fast cooling mechanism on the fusion path, the prompt dipole radiation could be of interest for the synthesis of super heavy elements through hot fusion reactions providing a way to cool down the hot fusion paths, so ending up with a larger survival probability. To shed light on this hypothesis, the dynamical dipole mode investigation was extended to a heavier compound nucleus, 192 Pb , by means of the 40 Ca + 152 Sm and 48 Ca + 144 Sm reactions at E lab= 11 and 10.1 MeV/nucleon, respectively. Preliminary results of this measurement, concerning both fusion-evaporation and fission events are presented.

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Zairi, Fahed, Jean Michel Remacle, Mohamed Allaoui, and Richard Assaker. "Delayed hypersensitivity reaction caused by metal-on-metal total disc replacement." Journal of Neurosurgery: Spine 19, no. 3 (September 2013): 389–91. http://dx.doi.org/10.3171/2013.6.spine121010.

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The authors report the case of a 53-year-old woman who underwent placement of a metal-on-metal total disc replacement (TDR) device for the treatment of discogenic back pain. The initial postoperative course was normal, but 2 months after surgery she started to complain of a recurrence of pain and she progressively developed cauda equina syndrome. Radiological and biological findings showed an inflammatory polyneuropathy associated with an epidural mass. A diagnosis of cell-mediated hypersensitivity reaction (Type IV) was made after patch testing showed positive reactions for 1% cobalt chloride and chromium. A decision was made to remove the TDR device and to perform a circumferential fusion. This report is intended to inform the reader that systemic metal release and hypersensitivity reaction are possible complications of metal-on-metal TDR.

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DAVARI, MEHDI D., AMENEH TAGHIZADEH, HOMAYOON BAHRAMI, and MANSOUR ZAHEDI. "THEORETICAL STUDY ON THE KINETICS AND MECHANISM OF THE REACTION OF CYCLOHEXYL ISOCYANIDE AND 1,1,1,5,5,5-HEXAFLUROPENTANE-2,4-DIONE USING DFT METHOD." Journal of Theoretical and Computational Chemistry 07, no. 06 (December 2008): 1227–50. http://dx.doi.org/10.1142/s021963360800443x.

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Kinetics and mechanism of the reaction between cyclohexyl isocyanide and 1,1,1,5,5,5-hexafluropentane-2,4-dione has been investigated by utilizing transition state theory and using B3LYP/6-31G* method. Based on previous experimental studies, two paths namely direct attack and conjugate addition have been proposed. Energy changes vs intrinsic reaction coordinate (IRC) along these paths have been studied both in the gas phase and considering nonspecific solvent effect under Onsager's model while all intermediate and possible transition states' geometries obtained and optimized. Small differences have been observed between gas phase and solution phase results. Taking advantage of the thermodynamic and kinetic calculated parameters, observed reaction rate constants and activation energies have been acquired. Computational results suggest that the conjugate addition path is totally unacceptable, while a new path has been proposed, which is both energetically and kinetically preferred to direct attack path. This new path undergoes the Michael addition along with a Cope–Claisen-type rearrangement. In this path, a new intermediate has been encountered for the first time, which contains a five-membered ring of four carbon atoms and one oxygen atom. NBO analysis has revealed that in such intermediate, oxygen lone pair has resonance with C – C π bond inside and C – N π bond outside of the ring leading to this species special stability. Molecular orbital calculations satisfy NBO findings.

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Liu, Yuli, and Paul W. Ayers. "Finding minimum energy reaction paths on ab initio potential energy surfaces using the fast marching method." Journal of Mathematical Chemistry 49, no. 7 (April 29, 2011): 1291–301. http://dx.doi.org/10.1007/s10910-011-9818-3.

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Castillo-García, Alvaro, Andreas W. Hauser, María Pilar de Lara-Castells, and Pablo Villarreal. "A Path Integral Molecular Dynamics Simulation of a Harpoon-Type Redox Reaction in a Helium Nanodroplet." Molecules 26, no. 19 (September 24, 2021): 5783. http://dx.doi.org/10.3390/molecules26195783.

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We present path integral molecular dynamics (PIMD) calculations of an electron transfer from a heliophobic Cs2 dimer in its (3Σu) state, located on the surface of a He droplet, to a heliophilic, fully immersed C60 molecule. Supported by electron ionization mass spectroscopy measurements (Renzler et al., J. Chem. Phys.2016, 145, 181101), this spatially quenched reaction was characterized as a harpoon-type or long-range electron transfer in a previous high-level ab initio study (de Lara-Castells et al., J. Phys. Chem. Lett.2017, 8, 4284). To go beyond the static approach, classical and quantum PIMD simulations are performed at 2 K, slightly below the critical temperature for helium superfluidity (2.172 K). Calculations are executed in the NVT ensemble as well as the NVE ensemble to provide insights into real-time dynamics. A droplet size of 2090 atoms is assumed to study the impact of spatial hindrance on reactivity. By changing the number of beads in the PIMD simulations, the impact of quantization can be studied in greater detail and without an implicit assumption of superfluidity. We find that the reaction probability increases with higher levels of quantization. Our findings confirm earlier, static predictions of a rotational motion of the Cs2 dimer upon reacting with the fullerene, involving a substantial displacement of helium. However, it also raises the new question of whether the interacting species are driven out-of-equilibrium after impurity uptake, since reactivity is strongly quenched if a full thermal equilibration is assumed. More generally, our work points towards a novel mechanism for long-range electron transfer through an interplay between nuclear quantum delocalization within the confining medium and delocalized electronic dispersion forces acting on the two reactants.

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Ardhany, Syahrida Dian, Susi Novaryatiin, Mohammad Rizki Fadhil Pratama, and Zulkhurnain Utar. "IRRITATION TEST OF BAWANG DAYAK (Eleutherine bulbosa(Mill.) Urb.) EXTRACT CREAM WITH HUMAN PATCH TEST METHOD." Jurnal Farmasi Sains dan Praktis 7, no. 1 (May 1, 2021): 74–80. http://dx.doi.org/10.31603/pharmacy.v7i1.4854.

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Topical agents indicated for the treatment of acne have the potential to cause irritation or allergic contact dermatitis. This study investigates the irritancy potential of anti-acne cream of bawang dayak (Eleutherine bulbosa (Mill.) Urb.) previously tested for microbiological effectiveness with the lowest concentration of 5% and the highest concentration of 20%. The method used in this study is the human patch test. A total of 20 volunteers were recruited for the patch test study, testing the cream. The result showed that all volunteers did not experience irritation both in the 5% or 20% bawang dayak extract cream formulations. However, the interview results were found that some volunteers experienced a slight itching without any significant skin adverse reactions on the cream application. Therefore, based on these initial findings it can be safely concluded that the cream of bawang dayak does not cause significant skin adverse reaction and good enough for further development for anti-acne cream dosage form.

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Altman-Price, Neta, and Moshe Mevarech. "Genetic Evidence for the Importance of Protein Acetylation and Protein Deacetylation in the Halophilic Archaeon Haloferax volcanii." Journal of Bacteriology 191, no. 5 (December 29, 2008): 1610–17. http://dx.doi.org/10.1128/jb.01252-08.

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ABSTRACT Protein acetylation and deacetylation reactions are involved in many regulatory processes in eukaryotes. Recently, it was found that similar processes occur in bacteria and archaea. Sequence analysis of the genome of the haloarchaeon Haloferax volcanii led to the identification of three putative protein acetyltransferases belonging to the Gcn5 family, Pat1, Pat2, and Elp3, and two deacetylases, Sir2 and HdaI. Intriguingly, the gene that encodes HdaI shares an operon with an archaeal histone homolog. We performed gene knockouts to determine whether the genes encoding these putative acetyltransferases and deacetylases are essential. A sir2 deletion mutant was able to grow normally, whereas an hdaI deletion mutant was nonviable. The latter is consistent with the finding that trichostatin A, a specific inhibitor of HdaI, inhibits cell growth in a concentration-dependent manner. We also showed that each of the acetyltransferases by itself is dispensable for growth but that deletion of both pat2 and elp3 could not be achieved. The corresponding genes are therefore “synthetic lethals,” and the protein acetyltransferases probably have a common and essential substrate.

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Leitich, Johannes, Ingeborg Heise, and Kurt Schaffner. "The reaction of some endo-5-acetyl norborn-2-enes with benzene thiol: a thermally induced non-allylic [1,3]-acetyl shift, as anticipated by a photochemical precedent." Canadian Journal of Chemistry 73, no. 11 (November 1, 1995): 1785–93. http://dx.doi.org/10.1139/v95-220.

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The thermal reaction of benzene thiol with rac-1-(4aS*,5R*,8S*,8aR*-5,8-methano-1,2,3,4,4a,5,8,8a-octahydro-4a-naphthyl)ethanone (10b), an endo-5-acetylnorborn-2-ene with a particularly close distance between one olefinic carbon and the keto carbon, and with its 8aS* epimer 10a, has been investigated. Besides the conventional unrearranged adducts 16a, b and 17a, b of the thiol to the C=C bonds of 10a, b, an adduct 18 was formed from 10b that involved a [1,3]-acetyl shift; no other products were formed. The dependence of adduct ratios on thiol concentration is consistent with two competing reactions of an intermediate radical 14b formed by addition of thiyl radical to the C=C bond of 10b, namely, abstraction of hydrogen from thiol (which is the conventional reaction path) vs. intramolecular attack of the radical on the keto group inducing the [1,3] shift of the latter. This shift constitutes an intramolecular variety of the known alkyl transposition reaction of ketones initiated by a reversible attack of an alkyl radical on a keto carbonyl group to generate an intermediate tert-alkoxyl radical; however, it is very much faster than the intermolecular reaction and corresponds to an effective molarity between 107 and 1010. These findings have a bearing on the mechanism of photorearrangements homologous to the ODPM (oxa-di-π-methane) photorearrangement, such as ODPE (oxa-di-π-ethane) and higher homologues, in that they support a two-step mechanism involving this type of acyl shift. Keywords: oxadi-π-methane photorearrangement; oxadi-π-ethane photorearrangement; acetyl shift, non-allylic [1,3]; thiol, addition to C=C bonds; norbornenes.

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Brodbaker, Elliott, and Melanie Pratt. "Contact Sensitivity to Aluminum." Journal of Cutaneous Medicine and Surgery 13, no. 4 (July 2009): 226–29. http://dx.doi.org/10.2310/7750.2008.08046.

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Purpose: To report two cases of aluminum contact dermatitis caused by different sources. Methods: Two patients were patch-tested for suspected contact sensitivities. Results: The results of patch testing revealed aluminum contact dermatitis reactions in both patients. Conclusion: Aluminum contact dermatitis is a rare finding with many possible etiologies. One should consider aluminum sensitivity when all patch test sites are positive when using aluminum Finn Chambers.

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Fischer, Stefan, and Martin Karplus. "Conjugate peak refinement: an algorithm for finding reaction paths and accurate transition states in systems with many degrees of freedom." Chemical Physics Letters 194, no. 3 (June 1992): 252–61. http://dx.doi.org/10.1016/0009-2614(92)85543-j.

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Biring, Shyamal Kumar, and Pinaki Chaudhury. "A stochastic optimization method based technique for finding out reaction paths in noble gas clusters perturbed by alkali metal ions." Chemical Physics 377, no. 1-3 (November 2010): 46–53. http://dx.doi.org/10.1016/j.chemphys.2010.08.014.

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Liddle, Brantley. "What Is the Temporal Path of the GDP Elasticity of Energy Consumption in OECD Countries? An Assessment of Previous Findings and New Evidence." Energies 15, no. 10 (May 21, 2022): 3802. http://dx.doi.org/10.3390/en15103802.

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This paper answers the question: what is the path of the GDP elasticity of economy-wide energy consumption for OECD countries over the period 1960–2019? To do so, this study first considers the arguments as to why this elasticity might change over time, and then reviews the previous evidence on whether this elasticity has changed over time. Lastly, the paper compiles and uses a new dataset to analyze whether the GDP elasticity of energy demand in OECD countries (i) has changed between the periods before and after the major energy crises (e.g., 1974–1985); and (ii) has been stable since 1986. Elasticity stability is analyzed via rolling window regressions using dynamic mean group cross-correlated errors. We argue that (i) the GDP elasticity for economy-wide energy consumption was around unity for OECD countries prior to the first energy crisis; and (ii) the reactions to the extreme oil price experiences that occurred over 1974–1985 led to a substantially lower GDP elasticity for economy-wide energy consumption of around 0.6 that has been stable at that level since the end of the second energy crisis (circa 1986). This demonstration of the path of the GDP elasticity is in contrast to some recent work that has suggested the GDP elasticity of energy has not changed (or changed very little) since the 1970s or even since the 1960s. Furthermore, this evidence that reactions to those extreme oil price experiences led to a step-function-like lowering of the GDP elasticity runs counter to other arguments that dematerialization, inverted-U-based development paths, or Kyoto Protocol ratification are responsible for continued declines in the GDP elasticity.

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Lasiman, E. T., F. D. Naufal, M. F. Anshor, A. Z. F. Syafira, D. Setianto, A. Ubaidillah, B. Rendy, et al. "DFT study of lithium diffusion in pristine La₂O₃." Journal of Physics: Conference Series 2243, no. 1 (June 1, 2022): 012108. http://dx.doi.org/10.1088/1742-6596/2243/1/012108.

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Abstract Surface coating can suppress side reactions between electrode and electrolyte in Lithium-Ion Batteries (LIBs) but may also affect the Li mobility when shuttling into / out from the electrode of a LIB. Lanthanum Oxide (La2O3) coating has been experimentally shown to enhance LIB performance. In this study, we investigate the diffusion of Li in pristine La2O3 to understand the enhanced electrochemical performance of several La2O3-coated Li-ion battery cathodes. We used Density Functional Theory (DFT) with Climbing Image Nudged Elastic Band (CI-NEB) to calculate the energy barrier and the diffusivity of Li. We considered three pathways, i.e., the octahedral-to-octahedral path (O-O), octahedral-tetrahedral-octahedral path (O-T-O), and octahedral-tetrahedral-tetrahedral-octahedral path (O-T-T-O), and our results suggest that the O-O pathway has the lowest Li energy barrier of 0.09 eV. This finding suggests that Li will preferably diffuse along the [010] direction. Furthermore, we find that Li will diffuse more slowly along the [001] direction.

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Engedahl, Unni, Adam A. Arvidsson, Henrik Grönbeck, and Anders Hellman. "Reaction Mechanism for Methane-to-Methanol in Cu-SSZ-13: First-Principles Study of the Z2[Cu2O] and Z2[Cu2OH] Motifs." Catalysts 11, no. 1 (December 25, 2020): 17. http://dx.doi.org/10.3390/catal11010017.

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As transportation continues to increase world-wide, there is a need for more efficient utilization of fossil fuel. One possibility is direct conversion of the solution gas bi-product CH4 into an energy-rich, easily usable liquid fuel such as CH3OH. However, new catalytic materials to facilitate the methane-to-methanol reaction are needed. Using density functional calculations, the partial oxidation of methane is investigated over the small-pore copper-exchanged zeolite SSZ-13. The reaction pathway is identified and the energy landscape elucidated over the proposed motifs Z2[Cu2O] and Z2[Cu2OH]. It is shown that the Z2[Cu2O] motif has an exergonic reaction path, provided water is added as a solvent for the desorption step. However, a micro-kinetic model shows that neither Z2[Cu2O] nor Z2[Cu2OH] has any notable activity under the reaction conditions. These findings highlight the importance of the detailed structure of the active site and that the most stable motif is not necessarily the most active.

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Martino, Mariangela, Cecilia Liberati, Benedetta Bua, Elisa Barbieri, Paola Costenaro, Costanza Di Chiara, Carlo Giaquinto, Ettore De Canale, Osvalda Rampon, and Daniele Donà. "Treatment for Severe Malaria: Post-Artesunate Delayed Haemolysis and Neutropenia." Healthcare 10, no. 3 (February 22, 2022): 413. http://dx.doi.org/10.3390/healthcare10030413.

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Parenteral artesunate (AS) is the WHO first-line treatment recommended in adults and children for severe malaria. Post-artesunate delayed haemolysis (PADH) is an uncommon adverse reaction to AS with a mechanism that is not fully understood, occurring in adults and children. Neutropenia is another possible finding after AS treatment, albeit rare. We present the case of a child who experienced both effects after treatment with AS for imported severe Falciparum malaria with very high parasitaemia. In addition, thirty-five paediatric cases of PADH, five cases of delayed anaemia without known haemolysis, and fourteen cases of neutropenia after artesunate treatment were identified from the literature review. PADH seems to be a dose-independent reaction and is not strongly related to hyperparasitaemia, although it is more frequent in this case. To date, the benefits of AS outweigh its potential side effects. However, haematological follow-up is mandatory to avoid possible complications from anaemia and neutropenia, especially in children treated with other contemporary drugs.

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Olsson, Mats H. M., Janez Mavri, and Arieh Warshel. "Transition state theory can be used in studies of enzyme catalysis: lessons from simulations of tunnelling and dynamical effects in lipoxygenase and other systems." Philosophical Transactions of the Royal Society B: Biological Sciences 361, no. 1472 (July 13, 2006): 1417–32. http://dx.doi.org/10.1098/rstb.2006.1880.

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The idea that enzyme catalysis involves special factors such as coherent fluctuations, quantum mechanical tunnelling and non-equilibrium solvation (NES) effects has gained popularity in recent years. It has also been suggested that transition state theory (TST) cannot be used in studies of enzyme catalysis. The present work uses reliable state of the art simulation approaches to examine the above ideas. We start by demonstrating that we are able to simulate any of the present catalytic proposals using the empirical valence bond (EVB) potential energy surfaces, the dispersed polaron model and the quantized classical path (QCP) approach, as well as the approximate vibronic method. These approaches do not treat the catalytic effects by phenomenological treatments and thus can be considered as first principles approaches (at least their ability to compare enzymatic reaction to the corresponding solution reactions). This work will consider the lipoxygenase reaction, and to lesser extent other enzymes, for specific demonstration. It will be pointed out that our study of the lipoxygenase reaction reproduces the very large observed isotope effect and the observed rate constant while obtaining no catalytic contribution from nuclear quantum mechanical (NQM) effects. Furthermore, it will be clarified that our studies established that the NQM effect decreases rather than increases when the donor–acceptor distance is compressed. The consequences of these findings in terms of the temperature dependence of the kinetic isotope effect and in terms of different catalytic proposals will be discussed. This paper will also consider briefly the dynamical effects and conclude that such effects do not contribute in a significant way to enzyme catalysis. Furthermore, it will be pointed out that, in contrast to recent suggestions, NES effects are not dynamical effects and should therefore be part of the activation free energy rather than the transmission factor. In view of findings of the present work and our earlier works, it seems that TST provides a quantitative tool for studies of enzyme catalysis and that the key open questions are related to the nature of the factors that lead to transition state stabilization.

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Khodayari-Rostamabad, Ahmad, Søren S. Olesen, Carina Graversen, Lasse P. Malver, Geana P. Kurita, Per Sjøgren, Lona L. Christrup, and Asbjørn M. Drewes. "Disruption of Cortical Connectivity during Remifentanil Administration Is Associated with Cognitive Impairment but Not with Analgesia." Anesthesiology 122, no. 1 (January 1, 2015): 140–49. http://dx.doi.org/10.1097/aln.0000000000000510.

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Abstract Background: The authors investigated the effect of remifentanil administration on resting electroencephalography functional connectivity and its relationship to cognitive function and analgesia in healthy volunteers. Methods: Twenty-one healthy male adult subjects were enrolled in this placebo-controlled double-blind cross-over study. For each subject, 2.5 min of multichannel electroencephalography recording, a cognitive test of sustained attention (continuous reaction time), and experimental pain scores to bone-pressure and heat stimuli were collected before and after infusion of remifentanil or placebo. A coherence matrix was calculated from the electroencephalogram, and three graph-theoretical measures (characteristic path-length, mean clustering coefficient, and relative small-worldness) were extracted to characterize the overall cortical network properties. Results: Compared to placebo, most graph-theoretical measures were significantly altered by remifentanil at the alpha and low beta range (8 to 18 Hz; all P < 0.001). Taken together, these alterations were characterized by an increase in the characteristic path-length (alpha 17% and low beta range 24%) and corresponding decrements in mean clustering coefficient (low beta range −25%) and relative small-worldness (alpha −17% and low beta range −42%). Changes in characteristic path-lengths after remifentanil infusion were correlated to the continuous reaction time index (r = −0.57; P = 0.009), while no significant correlations between graph-theoretical measures and experimental pain tests were seen. Conclusions: Remifentanil disrupts the functional connectivity network properties of the electroencephalogram. The findings give new insight into how opioids interfere with the normal brain functions and have the potential to be biomarkers for the sedative effects of opioids in different clinical settings.

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Journal articles on the topic 'Reaction path finding'

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