Ultrafast Spectroscopy And Computational Study Of The Photochemistry Of Diphenylphosphoryl Azide: Direct Spectroscopic Observation Of A Singlet Phosphorylnitrene

Mathematical and Physical Sciences: 2nd Place (The Ohio State University Edward F. Hayes Graduate Research Forum)In order to characterize the active site of human paraoxonase 1 (HuPON1), photochemistry of a possible photoaffinity label diphenylphosphoryl azide was studied by femtosecond transient absorption spectroscopy, chemical analysis of light-induced reaction products as well as by RI-CC2/TZVP and TD-B3LYP/TZVP computational methods. Theoretical methods predicted two possible mechanisms for singlet diphenylphosphorylnitrene formation from the photoexcited phosphoryl azide. (i) Energy transfer from the (π, π*) singlet excited state, localized on a phenyl ring, to the azide moiety, thereby leading to the formation of the singlet excited azide, which subsequently loses molecular nitrogen to form the singlet diphenylphosphorylnitrene. (ii) Direct irradiation of the azide moiety to form an excited singlet state of the azide, which in turn loses molecular nitrogen to form the singlet diphenylphosphorylnitrene. Two transient species were observed upon ultrafast photolysis (260 nm) of diphenylphosphoryl azide. The first transient absorption, centered at 475 nm (lifetime (τ) ~ 28 ps), was assigned to a (π, π*) singlet S1 excited state localized on a phenyl ring, and the second transient observed at 525 nm (τ ~ 480 ps) was assigned to singlet diphenylphosphorylnitrene. Experimental and computational results obtained from the study of diphenylphosphoramidate, along with the results obtained with diphenylphosphoryl azide, supported the mechanism of energy transfer from the singlet excited phenyl ring to the azide moiety, followed by nitrogen extrusion to form the singlet phosphorylnitrene. Ultrafast time-resolved studies performed on diphenylphosphoryl azide with the singlet nitrene quencher, tris(trimethylsilyl)silane, confirmed the spectroscopic assignment of singlet diphenylphosphorylnitrene to the 525 nm absorption band.A three-year embargo was granted for this item

Reactive Power Control in Electrical Power Transmission System

Abstract In this paper, an understanding of reactive power associated with power transmission networks is developed. To make transmission networks operate within desired voltage limits, methods of making up or taking away reactive powerhereafter called reactive-power control-are discussed. Before proceeding further, however, a thorough understanding of the reactive power in ac systems is necessary. This paper is not intended to provide a comprehensive analysis of transmission lines. Rather, its objective is to examine those aspects that enhance the understanding of the interplay between voltages on the line and the resulting reactive-power flows

EVALUATION OF THE INTERACTION OF PIPERINE WITH ANTIDEPRESSANT SERTRALINE AND ANALGESIC PENTAZOCINE, USING DIFFERENT ROUTES OF ADMINISTRATION IN ALBINO MICE

ABSTRACTObjective: To evaluate the effect of piperine on the antidepressant activity of sertraline and analgesic activity of pentazocine and to explore the effectof using oral and parenteral routes of administration on the possible interactions.Methods: Piperine was isolated from commercially obtained Piper nigrum extract. Swiss albino mice of either sex were divided into 8 groups (n=6)receiving: 2% gum acacia (oral, intraperitoneally [i.p.]), standard drug (oral, i.p.), standard drug + piperine (oral, i.p.), piperine (oral, i.p.). Tailsuspension test (TST) was used for antidepressant effect and Eddy's hot plate method for analgesic effect. Sertraline and pentazocine were used asstandard drugs (5 mg/kg) and piperine at 10 mg/kg.Result: In the TST, piperine alone (both routes) decreased immobility time, but the effect was statistically insignificant. Both combination groups(oral and i.p.) showed significantly better activity compared to sertraline oral and i.p. groups, respectively (p<0.05). Oral combination showed activitycomparable to i.p. combination (p>0.05). Piperine did not show any analgesic activity of its own (both routes). Piperine with pentazocine orallyshowed significantly better activity compared to pentazocine (oral) at 1, 2, and 4 hrs, and analgesia at 0.5 hr which pentazocine oral did not. Parenteralcombination was significantly better than pentazocine (i.p.) group at 2 and 4 hrs and better than oral combination at 4 hrs.Conclusion: Piperine has potential to be used in combination with pentazocine due to its bioenhancing effect and with sertraline due to a potentiating/additive effect which can help reduce dose and adverse effects of these drugs.Keywords: Piperine, Pentazocine, Sertraline, Albino mice, Bio enhancement, Potentiation

Electronic Properties Of 4-substituted Naphthalimides

This paper describes a study of excited-state properties of naphthalmide (NI) and four 4-substituted derivatives: 4-chloronaphthalimide (Cl-NI), 4-methylthionaphthalmide (MeS-NI), 4-nitronaphthalimide (O(2)N-NI), and 4-(N,N-dimethylaminonaphthalimide (Me(2)N-NI). Steady-state absorption and fluorescence spectra were collected in solvents of varying polarity to determine the excited-state character of NI derivatives. Furthermore. the excited-state dynamics were studied Using femtosecond transient absorption spectroscopy. The experimental findings were compared to calculated data obtained using time-dependent density functional (TD-DFT) methods. We found that light absorption by all NI derivatives leads to the production of the second excited state (S(2)), which was found to have a n,pi* character. Within similar to 40 ps, the S(2) state undergoes internal conversion to produce the S(1) state. The S(1) state is relatively long-lived (similar to 4 ns) and has charge-transfer character in NI derivatives with electron-withdrawing and electron-donating groups (MeS-NI, O(2)N-Ni, and Me(2)N-NI). In the case of NI and Cl-NI, the S(1) state has a pi,pi* character and undergoes intersystem crossing to produce the T(1) state within 400 ps

Trajectory Optimization and Following for a Three Degrees of Freedom Overactuated Floating Platform

Space robotics applications, such as Active Space Debris Removal (ASDR), require representative testing before launch. A commonly used approach to emulate the microgravity environment in space is air-bearing based platforms on flat-floors, such as the European Space Agency's Orbital Robotics and GNC Lab (ORGL). This work proposes a control architecture for a floating platform at the ORGL, equipped with eight solenoid-valve-based thrusters and one reaction wheel. The control architecture consists of two main components: a trajectory planner that finds optimal trajectories connecting two states and a trajectory follower that follows any physically feasible trajectory. The controller is first evaluated within an introduced simulation, achieving a 100 % success rate at finding and following trajectories to the origin within a Monte-Carlo test. Individual trajectories are also successfully followed by the physical system. In this work, we showcase the ability of the controller to reject disturbances and follow a straight-line trajectory within tens of centimeters.Comment: Accepted to IROS2022, code at https://gitlab.com/anton.bredenbeck/ff-trajectorie

Pinpointing The Extent Of Electronic Delocalization In The Re(i)-to-tetrazine Charge-separated Excited State Using Time-resolved Infrared Spectroscopy

Femtosecond mid-IR transient absorption spectroscopy (TRIR) and time-dependent density functional theory (TD-DFT) calculations on Re(CO)(3)Cl(Me(2)BPTZ) [Me(2)BPTZ = 3,6-bis(5-methyl-2-pyridine)-1,2,4,5-tetrazine] are used to demonstrate that the lowest excited state of the complex is a triplet metal-to-ligand charge-transfer ((3)MLCT) state with a lifetime of 225 ps. The short excited-state lifetime is explained by the energy-gap taw. Vibrational cooling of the (3)MLCT state shows up as early-time dynamics (3.6 ps). The structural changes in the excited state are deduced from the frequency shifts in the TRIR vibrational bands. The vibrational frequencies of the CO groups increase upon excitation as a result of decreased back-bonding between the CO ligands and the oxidized Re center in the (3)MLCT state. The vibrational frequencies of the central tetrazine ring of Me(2)BPTZ decrease because of the decrease in the bond order upon reduction of the Me(2)BPTZ ligand in the (3)MLCT state. Interestingly, the TRIR signals from the pyridine moieties of Me2BPTZ were not detected. These results can be explained by localization of the electronic charge on the central tetrazine ring in the (3)MLCT state of Re(CO)(3)Cl(Me(2)BPTZ), as supported by TD-DFT calculations

Finding and Following Optimal Trajectories for an Overactuated Floating Robotic Platform

The recent increase in yearly spacecraft launches and the high number of planned launches have raised questions about maintaining accessibility to space for all interested parties. A key to sustaining the future of space-flight is the ability to service malfunctioning - and actively remove dysfunctional spacecraft from orbit. Robotic platforms that autonomously perform these tasks are a topic of ongoing research and thus must undergo thorough testing before launch. For representative system-level testing, the European Space Agency (ESA) uses, among other things, the Orbital Robotics and GNC Lab (ORGL), a flat-floor facility where air-bearing based platforms exhibit free-floating behavior in three Degrees of Freedom (DoF). This work introduces a representative simulation of a free-floating platform in the testing environment and a software framework for controller development. Finally, this work proposes a controller within that framework for finding and following optimal trajectories between arbitrary states, which is evaluated in simulation and reality.Comment: 16th Symposium on Advanced Space Technologies in Robotics and Automation 202

Mechanism Of N(5)-ethyl-flavinium Cation Formation Upon Electrochemical Oxidation Of N(5)-ethyl-4a-hydroxyflavin Pseudobase

We investigated the oxidation behavior of 5-ethyl-4a-hydroxy-3-methy1-4a,5-dihydrolumitlavin (pseudobase Et-FlH) in acetonitrile with the aim of determining if the two-electron oxidized Et-FlOH(2+) undergoes a release of hydroxyl cation and the production of 5-ethyl-3methyllumiflavinium cation (Et-Fl(+)). The focus of this work is to investigate the possibility of using Et-FlOH as a catalyst for water oxidation. The cyclic voltammetry demonstrates that Et-FlOH exhibits two one-electron oxidation potentials at +0.95 and +1.4 V versus normal hydrogen electrode (NHE), with the second oxidation potential being irreversible. The production of Et-FY\u27 is observed in the cyclic voltammetry of Et-FlOH and has been previously assigned to the release of OH(+) from the two-electron oxidized Et-FlOH(2+). The results of our study show that this is not the case: (i) we performed bulk electrolysis of the electrolyte solution at +2 V and then added Et-FlOH to the electrolyzed solution. We found that Et-Fr is produced from this solution, even though Et-FlOH itself was not oxidized; (ii) reactions of Et-FlOH with chemical oxidants (eerie ammonium nitrate, nitrosyl tetrafluoroborate, and tetrabutylammonium persulfate) demonstrate. that Et-Fl(+) production occurs only in the presence of strong Lewis acids, such as Ce(4+) and NO(+) ions. On the basis of these results, we propose that the production of Et-Fl+ in the electrochemistry of Et-FlOH(-1) occurs because of the shift in the Et-FlOH/Et-Fl+ acid base equilibrium in the presence of protons released during anodic oxidation. We identified two sources of protons: (i) oxidation of traces of water present in the acetonitrile releases oxygen and protons and (ii) two-electron oxidized Et-FlOH(2+) releases protons located on the N(5)-alkyl chain. The release of protons from Et-FlOH(2+) was confirmed by cyclic voltammetry of Et-FlOH in the presence of pyridine as a base. The first oxidation peak of Et-FlOH at +0.95 V is reversible in the absence of pyridine. The addition of pyridine leads to the shift of the oxidation potential to a less positive value, which is consistent with a proton-coupled electron transfer (PCET). Furthermore, the anodic current increases, and the cathodic peak becomes irreversible, giving rise to two additional reduction peaks at -0.2 and -1 V. The same reduction peaks were observed in the high scan rate cyclic voltammogram of Et-FlOH in the absence of pyridine, implying that the release of protons indeed occurs from Et-FlOH(2+). To determine which functional group of Et-FlOH(center dot+) is the source of protons, we performed DFT calculations at the B3LYP/6-311++G level of theory for a reaction of Et-FlOH(center dot+). with pyridine and identified two proton sources: (i) the \u3eN-CH(2)(-) group of the N(5) alkyl chain and (ii) the OH group in the 4a-position of the radical cation. Because the appearance of new reduction peaks at 0.2 and 1.0 V occurs in the model compound that lacks OH protons (Et-FlOMe), we conclude that the proton removal occurs predominantly from the \u3eN-CH(2)- moiety

Virosome: A vector in vaccine delivery

These days vaccines are considered the best economical and effective technique for preventing and handling bacterial infections, like human papillomavirus (HPV) or meningitis, allergies, autoimmune Relevant Disorders, Microbial Infections, and many more viral diseases. Annually millions of lives are saved from death-causing infections and other relevant disorders with the help of proper immunization with the help of vaccines. But still, many diseases are not yet preventable by vaccines and there is a chance of the improvement of current vaccines with help of many approaches. One of these is a compound known as a virosome, which is produced when pure haemagglutinin and neuraminidase projections of the influenza virus surface are removed from viral envelope and deposited on the exterior of unilamellar liposomes.Studies have shown that in order to attain the desired therapeutic effect, a physical attachment between the target antigen and the virosomal carrier is necessary. A virosome can bind to and “infect” host cells and deliver the antigen directly into the processing pathway which is an Alternatively, the virosome may be phagocytosed by an APC. So Our review gives a novel idea of the vector technology for vaccine delivery, its properties, method of preparation, and importance as well as some applications of different virosomal vaccine discoveries