Holographic Complexity of LST and Single Trace TTˉT\bar{T}

In this work, we continue our study of string theory in the background that interpolates between $AdS_3$ in the IR to flat spacetime with a linear dilaton in the UV. The boundary dual theory interpolates between a CFT$_2$ in the IR to a certain two-dimensional Little String Theory (LST) in the UV. In particular, we study \emph{computational complexity} of such a theory through the lens of holography and investigate the signature of non-locality in the short distance behavior of complexity. When the cutoff UV scale is much smaller than the non-locality (Hagedorn) scale, we find exotic quadratic and logarithmic divergences (for both volume and action complexity) which are not expected in a local quantum field theory. We also generalize our computation to include the effects of finite temperature. Up to second order in finite temperature correction, we do not any find newer exotic UV-divergences compared to the zero temperature case.Comment: Appendix A and few references added. 28 pages+1 appendi

Hydrovinylation of Olefins Catalyzed by an Iridium Complex via CH Activation

Olefin dimerizations are typically proposed to proceed via a Cossee−Arlman type migratory mechanism involving relatively electron-rich metal hydrides. We provide experimental evidence and theoretical calculations that show, in contrast, relatively electron-poor O-donor Ir complexes can catalyze the dimerization of olefins via a mechanism that involves olefin CH bond activation and insertion into a metal−vinyl intermediate

Benzene C−H Bond Activation in Carboxylic Acids Catalyzed by O-Donor Iridium(III) Complexes: An Experimental and Density Functional Study

The mechanism of benzene C−H bond activation by [Ir(μ-acac-O,O,C^3)(acac-O,O)(OAc)]_2 (4) and [Ir(μ-acac-O,O,C^3)(acac-O,O)(TFA)]_2 (5) complexes (acac = acetylacetonato, OAc = acetate, and TFA = trifluoroacetate) was studied experimentally and theoretically. Hydrogen−deuterium (H/D) exchange between benzene and CD_(3)COOD solvent catalyzed by 4 (ΔH^‡ = 28.3 ± 1.1 kcal/mol, ΔS^‡ = 3.9 ± 3.0 cal K^(−1) mol^(−1)) results in a monotonic increase of all benzene isotopologues, suggesting that once benzene coordinates to the iridium center, there are multiple H/D exchange events prior to benzene dissociation. B3LYP density functional theory (DFT) calculations reveal that this benzene isotopologue pattern is due to a rate-determining step that involves acetate ligand dissociation and benzene coordination, which is then followed by heterolytic C−H bond cleavage to generate an iridium-phenyl intermediate. A synthesized iridium-phenyl intermediate was also shown to be competent for H/D exchange, giving similar rates to the proposed catalytic systems. This mechanism nicely explains why hydroarylation between benzene and alkenes is suppressed in the presence of acetic acid when catalyzed by [Ir(μ-acac-O,O,C^3)(acac-O,O)(acac-C^3)]_2 (3) (Matsumoto et al. J. Am. Chem. Soc. 2000, 122, 7414). Benzene H/D exchange in CF_(3)COOD solvent catalyzed by 5 (ΔH^‡ = 15.3 ± 3.5 kcal/mol, ΔS^‡ = −30.0 ± 5.1 cal K^(−1) mol^(−1)) results in significantly elevated H/D exchange rates and the formation of only a single benzene isotopologue, (C_(6)H_(5)D). DFT calculations show that this is due to a change in the rate-determining step. Now equilibrium between coordinated and uncoordinated benzene precedes a single rate-determining heterolytic C−H bond cleavage step

STRATEGIES FOR FACIAL NERVE PROTECTION DURING PAROTID GLAND SURGERY, A PROSPECTIVE STUDY: USING THE TRAGAL POINTER, POSTERIOR BELLY OF DIGASTRIC AND MASTOID TIP AS LANDMARKS FOR FACIAL NERVE TRUNK IDENTIFICATION IN PAROTID SURGERY.

Background: In order to decrease the likelihood of facial nerve paralysis and address postoperative issues, our goal was to share our experience with parotid surgery. Methods: A 2 year research involving 40 patients with parotid edoema was conducted. Prior to the procedure, a cautious clinical assessment, an examination of the patient's medical history, and a facial nerve evaluation were carried out. These 40 patients (24 men and 16 women) who had parotid edoema underwent parotidectomy using techniques for an antegrade strategy over a period of two years. Results: Each of the 40 patients had a superficial parotidectomy. Thirteen patients (32.5%) exhibited impairments in facial loss of nerve mobility, with seven having HB II (17.5%), four having HB Scale III (10%), and six having HB IV (15%). The majority of patients (18/30 patients) in this study showed significant recovery between four to six months following the procedure of surgery (mean time for recovery: 7 months), and patients affected had recovered in the time duration of 11 months of parotidectomy. Conclusion: To reduce the likelihood of transient facial nerve paresis, the following safety measures were used in this investigation “vertical retraction” to lower the possibility of traction injuries. Bipolar diathermy was performed after the nerve trunk was located, and surgical sutures (5/0 polyglactin) were used to create hemostasis. With a sensitivity of 67% and a specificity of 13%, FNAC remains the investigation of choice. The numerical outcomes of the many parameters that were evaluated show that they are consistent with research from previous studies and the medical literature. Recommendation: The techniques discussed in the study if employed can significantly reduce the risk of facial nerve dysfunction. Thus, while performing Parotid gland surgery the technique should be employed

Synthesis, Structure, and Reactivity of O-Donor Ir(III) Complexes: C−H Activation Studies with Benzene

Various new thermally air- and water-stable alkyl and aryl analogues of (acac-O,O)_2Ir(R)(L), R−Ir−L (acac-O,O = κ^2-O,O-acetylacetonate, −Ir− is the trans-(acac-O,O)_2Ir(III) motif, R = CH_3, C_2H_5, Ph, PhCH_2CH_2, L = Py) have been synthesized using the dinuclear complex [Ir(μ-acac-O,O,C^3)−(acac-O,O)(acac-C^3)]_2, [acac-C−Ir]_2, or acac-C−Ir−H_2O. The dinuclear Ir (III) complexes, [Ir(μ-acac-O,O,C^3)−(acac-O,O)(R)]_2 (R = alkyl), show fluxional behavior with a five-coordinate, 16 electron complex by a dissociative pathway. The pyridine adducts, R−Ir−Py, undergo degenerate Py exchange via a dissociative mechanism with activation parameters for Ph−Ir−Py (ΔH^‡ = 22.8 ± 0.5 kcal/mol; ΔS^‡ = 8.4 ± 1.6 eu; ΔG^‡_(298K) = 20.3 ± 1.0 kcal/mol) and CH_3−Ir−Py (ΔH^‡ = 19.9 ± 1.4 kcal/mol; ΔS^‡ = 4.4 ± 5.5 eu; ΔG^‡_(298K) = 18.6 ± 0.5 kcal/mol). The trans complex, Ph−Ir−Py, undergoes quantitatively trans-cis isomerization to generate cis-Ph−Ir−Py on heating. All the R−Ir−Py complexes undergo quantitative, intermolecular CH activation reactions with benzene to generate Ph−Ir−Py and RH. The activation parameters (ΔS^‡ =11.5 ± 3.0 eu; ΔH^‡ = 41.1 ± 1.1 kcal/mol; ΔG^‡_(298k) = 37.7 ± 1.0 kcal/mol) for CH activation were obtained using CH_3−Ir−Py as starting material at a constant ratio of [Py]/[C_6D_6] = 0.045. Overall the CH activation reaction with R−Ir−Py has been shown to proceed via four key steps:  (A) pre-equilibrium loss of pyridine that generates a trans-five-coordinate, square pyramidal intermediate; (B) unimolecular, isomerization of the trans-five-coordinate to generate a cis-five-coordinate intermediate, cis-R−Ir-□; (C) rate-determining coordination of this species to benzene to generate a discrete benzene complex, cis-R−Ir−PhH; and (D) rapid C−H cleavage. Kinetic isotope effects on the CH activation with mixtures of C_6H_6/C_6D_6 (KIE = 1) and with 1,3,5-C_6H_3D_3 (KIE ∼3.2 at 110 °C) are consistent with this reaction mechanism

GREEN SYNTHESIS, CHARACTERIZATION AND ANTIBACTERIAL ACTIVITY OF SILVER NANOPARTICLES

Metallic nanoparticles have gained the interest of researchers worldwide due to their unique antibacterial, antimicrobial and anti-inflammatory properties. There is a constant need for the sustainable green synthesis of the metallic nanoparticles with less involvement of the toxic chemicals. In this background, our group has synthesised the silver nanoparticles from the aqueous extracts of clove and cinnamon through green method. The aqueous spice extracts were used for the reduction of silver nitrate solution. The synthesised silver nanoparticles were characterised by the UV-Visible spectroscopy, dynamic light scattering (DLS) and transmission electron microscopy (TEM). Antibacterial properties of the nanoparticles were evaluated on the Escherichia coli and Staphylococcus aureus strains using the Kirby-Bauer antibiotic testing method. UV-Vis spectroscopy confirms the size of the nanoparticles to be around 30-60 nm which is further confirmed by the DLS and TEM techniques. Further, the antibacterial activity analysis showed that the bacterial samples (S. aureus and E. coli) treated with the synthesised silver nanoparticles showed minimum inhibitory concentration in the range of 25-30 μM. The study presents an environment friendly method to synthesise metallic nanoparticles showing good antibacterial activity. This work would help other research groups working in the field of biological application of green synthesis mediated metallic nanoparticles