Bimolecular photodissociation of interstellar 1-Cyanonaphthalene via Intermolecular Coulombic decay.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in space and govern the interstellar chemistry. The two isomers of cyanonaphthalene (1-CNN and 2-CNN) were the first PAHs to be recently identified in the Taurus Molecular Cloud (TMC-1). Their large abundance is attributed to high photostability with nearly no photofragmentation at photon energies above the ionization potential. Here, we show that at ambient light and at densities akin to dense molecular clouds and the upper atmosphere of planets and moons, 1-CNN could undergo extensive fragmentation through a new mechanism leading to daughter cations. On UV photoexcitation, at a photon energy way below the ionization threshold, 1-CNN monomers form photoexcited dimer units. Intermolecular Coulombic decay between the two photoexcited units of the dimer leads to ionization, and the subsequent molecular rearrangements form new daughter cations. These daughter cations could react further, contributing to rich bottom-up astrochemistry, and could play a pivotal role in developmental astrobiology. Photofragmentation in atmospheric and astrophysical environments is hitherto known to be unimolecular, while the present results point a pathway involving bimolecular photofragmentation.

A Comparative Study to Assess Utility of Olfactory and Gustatory Dysfunctions in the Diagnosis of Covid-19.

COVID-19 is a global pandemic which has infected more than 100 million individuals and having taken a big toll on the world in terms of morbidity and mortality. The disease may progress in some patients from an influenza like illness to sever acute respiratory illness. Diagnosis of COVID 19 by RTPCR supported by radiological evidence, Material: In this prospective observational study, 60 COVID- 19 positive patients and 60 COVID negative/ suspect patients respectively were enrolled from march 2020 to July 2020 in Bowring and lady Curzon Hospital, Bangalore and they were assessed for taste and smell sensations based on SQOD- NS and questions based on smell and taste component of NHNE survey, symptomatic patients were followed up and duration needed for recovery of symptoms was analysed for P value, chi-square value, other relevant blood and radiological investigations were done. Observation: 1. To compare the olfactory and gustatory dysfunctions in COVID suspects and patients with laboratory-confirmed COVID-19 infection. 2. To assess utility of hypoguesia and hyposmia as discriminant clinical features that might be used for the diagnosis of COVID-19 in patients with ILI. Conclusion: We concluded that patients with COVID 19 positive status had severe spectrum of olfactory dysfunction like anosmia, hyposmia and they will have long recovery time compared to COVID negative /suspect patients .Taste perception was more impaired in COVID positive patients compared to COVID negative /suspects.Covid positive patients had higher sQOD-NS score compared to COVID negative patients and significant associations are seen.

Physiologic lead placement with electroanatomic mapping: A case series.

INTRODUCTION: His bundle pacing (HBP) and left bundle branch area pacing (LBBAP) have emerged as attractive alternatives to traditional biventricular pacing to achieve cardiac resynchronization therapy. Early reported results have been inconsistent, particularly amongst patients in whom initial placement with traditional approaches has been unsuccessful or those with complex anatomy or congenital abnormalities. In this report, we describe the use of three-dimensional electroanatomic mapping (EAM) in five selected cases. METHODS: Five patients from multiple clinical sites underwent EAM-guided HBP or LBBAP by highly trained electrophysiologists with significant experience with conduction system pacing. Each patient in this series underwent EAM-guided conduction system pacing due to complex anatomy and/or prior failed lead implantation. RESULTS: EAM-guided lead implantation was successful in all five cases. Capture thresholds were relatively low and patients continued to have evidence of successful lead implantation with minimum 1-month follow-up. The fluoroscopy time varied, likely owing to the variable complexity of the cases. CONCLUSIONS: The use of EAM, in combination with traditional intracardiac electrograms with or without fluoroscopy, allows more targeted and precise placement of leads for HBP and LBBAP pacing. Further investigation is needed to determine this strategy's long-term performance and to optimize patient selection.

Polytetrafluoroethylene Is a Safe and Effective Interposition Conduit for Caval Reconstruction After Resection of Primary Leiomyosarcoma of the Inferior Vena Cava.

BACKGROUND: Primary leiomyosarcoma of the inferior vena cava (IVC) is a rare soft tissue sarcoma. Techniques for caval reconstruction after tumor resection vary widely. Our single-center experience serves as one of the largest reviews of caval reconstruction using polytetrafluoroethylene (PTFE) interposition grafts published in the past 10 years. METHODS: We conducted a single-center retrospective review of all patients who had undergone surgical resection of IVC leiomyosarcomas since January 1, 2007. Information regarding the procedure and patient-specific data was obtained from the institution's electronic medical record. RESULTS: We identified 4 patients (3 women and 1 man) who had undergone surgical resection for IVC leiomyosarcoma with PTFE graft reconstruction. Adjunct procedures (i.e., arteriovenous fistulas) were not used to maintain graft patency. There was no perioperative mortality within our patient population. One patient returned within 30 days with an acute kidney injury associated with a partially occlusive thrombus in the proximal part of the PTFE conduit. Another patient was found to have infolding of the PTFE graft due to inappropriate graft oversizing at the time of the index operation. Two patients developed distant metastases within a year of surgery, despite having tumor-free margins at the time of the initial operation. All the PTFE interposition grafts remained patent throughout the follow-up without the need for an additional intervention. CONCLUSIONS: PTFE interposition graft may be a safe and effective conduit for caval reconstruction after resection of a primary leiomyosarcoma of the IVC, but further research is necessary to establish appropriate management guidelines.

A 22-pole radiofrequency ion trap setup for laboratory astrophysical studies.

The formation of large interstellar molecules starting from small reactants constitutes the bottom-up approach in astrochemistry. An experimental setup wherein the ionic reactant is prepared and allowed to react with neutral reactants within a confined interaction space is most desirable for this approach. Here, we present our efforts in constructing a 22-pole radio-frequency ion trap experimental setup that could act as a reaction chamber for the neutral reactant and trapped ions. A compact piezo-based pulsed supersonic expansion discharge source was developed to achieve efficient production of anions, particularly metal-bearing ions. In addition, two other ion sources, namely, the electron impact ion source and the plasma supersonic discharge ion source, were developed to cater to the production of specific ions. The geometry of this experimental setup facilitates photo excitation of trapped ions. The trapping efficiency was studied by trapping SF5+ and SF6- for a few seconds. The control exhibited by various parameters on the efficiency of the trapping is discussed in detail. Potential studies that could be performed with this new experimental setup are also discussed.

Paraneoplastic gastrointestinal dysmotility due to non-Hodgkin diffuse large B cell lymphoma: a case report.

Paraneoplastic gastrointestinal dysmotility is a rare entity which occurs in association with malignancy. We present the second case associated with lymphoma, characterised by generalised gastrointestinal dysmotility with constipation, malnutrition, weight loss, and capsule endoscope retention. This case highlights the importance of maintaining a high index of suspicion for malignancy in patients with unexplained gastrointestinal dysmotility.

A first report on the spatial and temporal variability of microplastics in coastal soils of an urban town in south-western India: Pre- and post-COVID scenario.

We present a first study on the temporal changes (2019-2021) in the microplastic abundance in the coastal soils of an urban town in the south-western part of India. All sampling stations exhibited higher abundances of microplastics in soils collected during 2021 (959.7 ± 277.7 particles/kg) compared to those collected in 2019 (515.1 ± 182.7 particles/kg). Morphologically, flakes, fibres, and films are the most abundant types documented in the soil environment. The microplastics of 0.3-5 mm size are relatively more abundant (60.6 %) compared to those of 0.03-0.3 mm size (39.4 %) in 2021. The three main types of polymers (polypropylene and high- and low-density polyethylene) in the soil exhibited an increase in abundance during an interval of 15 months (October 2019 to March 2021). In addition to packaging materials, the enhanced use of surgical masks during the COVID-19 period might have acted as a source of microplastic contamination in the soils.

Molecular growth of PANH via intermolecular Coulombic decay.

Nitrogen-bearing polycyclic aromatic hydrocarbons (PANHs) are ubiquitous in space. They are considered precursors to advanced biomolecules identified in meteorites. However, their chemical evolution into biomolecules in photodestructive astrophysical mediums remains a paradox. Here, we show that light can efficiently initiate the molecular mass growth of PANHs. Ultraviolet-photoexcited quinoline monomers, the smallest PANH, were observed to associate and intermolecular Coulombic decay between the associating monomers formed the cations of quinoline-dimer. Molecular rearrangements in the dimer cation lead to a dominant formation of cations heavier than quinoline. The enrichment of these heavier cations over all the other cations reveals the efficiency of this route for the mass growth of PANHs in space. This mechanism also leads to a highly reactive unsaturated PANH-ring via CH loss, a hitherto unknown channel in any photon-driven process. The occurrence of this efficient pathway toward complex molecules points to a rich chemistry in dense interstellar clouds.

Photodissociation pathways and lifetimes of protonated peptides and their dimers.

Photodissociation lifetimes and fragment channels of gas-phase, protonated YA(n) (n = 1,2) peptides and their dimers were measured with 266 nm photons. The protonated monomers were found to have a fast dissociation channel with an exponential lifetime of ~200 ns while the protonated dimers show an additional slow dissociation component with a lifetime of ~2 µs. Laser power dependence measurements enabled us to ascribe the fast channel in the monomer and the slow channel in the dimer to a one-photon process, whereas the fast dimer channel is from a two-photon process. The slow (1 photon) dissociation channel in the dimer was found to result in cleavage of the H-bonds after energy transfer through these H-bonds. In general, the dissociation of these protonated peptides is non-prompt and the decay time was found to increase with the size of the peptides. Quantum RRKM calculations of the microcanonical rate constants also confirmed a statistical nature of the photodissociation processes in the dipeptide monomers and dimers. The classical RRKM expression gives a rate constant as an analytical function of the number of active vibrational modes in the system, estimated separately on the basis of the equipartition theorem. It demonstrates encouraging results in predicting fragmentation lifetimes of protonated peptides. Finally, we present the first experimental evidence for a photo-induced conversion of tyrosine-containing peptides into monocyclic aromatic hydrocarbon along with a formamide molecule both found in space.

Ambient-light-induced intermolecular Coulombic decay in unbound pyridine monomers.

Intermolecular Coulombic decay (ICD) is a process whereby photoexcited molecules relax by ionizing their neighbouring molecules. ICD is efficient when intermolecular interactions are active and consequently it is observed only in weakly bound systems, such as clusters and hydrogen-bonded systems. Here we report an efficient ICD between unbound molecules excited at ambient-light intensities. On the photoexcitation of gas-phase pyridine monomers, well below the ionization threshold and at low laser intensities, we detected the parent and heavier-than-parent cations. The isotropic emission of slow electrons revealed ICD as the underlying process. π-π* excitation in unbounded pyridine monomers triggered an associative interaction between them, which leads to an efficient three-centre ICD. The cation resulting from the molecular association of the three pyridine centres relaxed through fragmentation. This below-threshold ionization under ambient light has implications for the understanding of radiation damage and astrochemistry.

Spectral tuning of the photoactive yellow protein chromophore by H-bonding.

Spectral tuning in the photoactive yellow protein (PYP) is investigated by performing gas-phase absorption measurements on a PYP-model chromophore with two water molecules hydrogen-bonded to it. The photoabsorption maximum shows an unusually large blue shift of 0.71 eV in going from the bare to the hydrogen-bonded chromophore. It is concluded that several interactions within the PYP protein are mutually cancelling each other, yielding an absorption maximum that is close to the absorption maximum of the bare chromophore. The system breaks apart upon photoexcitation in the gas phase by releasing the two water molecules, leaving the chromophore itself intact. The hydrogen-bonding interactions thus play an important role in stabilizing the gas phase chromophore against photofragmentation. The relaxation dynamics for the breakup process was also studied, and the timescale of relaxation via fragmentation was found to be < 25 ns.

Sub-microsecond photodissociation pathways of gas phase adenosine 5'-monophosphate nucleotide ions.

The sub-microsecond dissociation pathways for the protonated and deprotonated forms of adenosine 5'-monophosphate were probed in the gas phase using a linear time of flight spectrometer. The studies show two dissociation pathways for the AMP ions indicating dominant ergodic pathways in the photodissociation of these species. The photofragmentation was determined to be a single photon process for the AMP ions. Photodetachment of the AMP anion excited at 266 nm was not observed, leaving dissociation as the prominent pathway for relaxation of the excess energy in the biomolecule. The photofragments were analysed at the electrostatic ion storage ring (ELISA) and found to be similar to collision induced fragments in the case of anions but different in the case of cations.

Dissociation lifetime studies of doubly deprotonated angiotensin peptides.

The doubly deprotonated [Asn,Val5] angiopeptide, in the gas phase, was irradiated with 266 nm photons. The time of flight (TOF) of the products formed following photoabsorption, namely, the monoanion and neutral fragments, was recorded with submicrosecond time resolution. Monte Carlo simulations of the TOF of the neutral fragments indicate that the dissociation occurs faster than 100 ns. A similar experiment performed on the Val5 angiopeptide also yielded a dissociation time shorter than 100 ns. We suggest dissociation mechanisms that account for the different number of photons required for the release of CO2.

Retrospective review of 290 small carotid cave aneurysms over 17 years.

OBJECTIVE: The carotid cave is a unique intradural region located along the medial aspect of the internal carotid artery. Small carotid cave aneurysms confined within this space are bound by the carotid sulcus of the sphenoid bone and are thought to have a low risk of rupture or growth. However, there is a lack of data on the natural history of this subset of aneurysms. METHODS: The authors present a retrospective case series of 290 small (≤ 4 mm) carotid cave aneurysms evaluated and managed at their institution between January 2000 and June 2017. RESULTS: No patient presented with a subarachnoid hemorrhage attributable to a carotid cave aneurysm, and there were no instances of aneurysm rupture or growth during 911.0 aneurysm-years of clinical follow-up or 726.3 aneurysm-years of imaging follow-up, respectively. CONCLUSIONS: This series demonstrates the benign nature of small carotid cave aneurysms.

Transforaminal sacral approach for spinal anesthesia in orthopedic surgery: A novel approach.

Regional anesthesia is preferred world-wide for its distinct advantages. The benefits of regional anesthesia in patients with comorbid conditions are well-established. The administration of regional anesthesia can sometimes pose a challenge to the anesthesiologist due to the structural abnormalities of the spine. The most common difficulty encountered for spinal anesthesia in our hospital (Nalgonda District) is skeletal fluorosis. Apart from the midline approach, paramedian, and Taylor's approaches are advocated for difficult scenarios. This article reports two orthopedic cases, conducted under a novel spinal anesthesia technique, i.e., transforaminal sacral approach under C-arm guidance with a successful outcome. The sacral foraminal subarachnoid block is a method to access the subarachnoid space through the upper posterior sacral foramina.