Structure and Spectroscopic Insights for CH3PCO Isomers: A High-Level Quantum Chemical Study.

The exploration of phosphorus-bearing species stands as a prolific field in current astrochemical research, particularly within the context of prebiotic chemistry. Herein, we have employed high-level quantum chemistry methodologies to predict the structure and spectroscopic properties of isomers composed of a methyl group and three P, C, and O atoms. We have computed relative and dissociation energies, as well as rotational, rovibrational, and torsional parameters using the B2PLYPD3 functional and the explicitly correlated coupled cluster CCSD(T)-F12b method. Based upon our study, all the isomers exhibit a bent heavy atom skeleton with CH3PCO being the most stable structure, regardless of the level theory employed. Following in energy, we found four high-energy isomers, namely, CH3OCP, CH3CPO, CH3COP, and CH3OPC. The computed adiabatic dissociation energies support the stability of all [CH3, P, C, O] isomers against fragmentation into CH3 and [P, C, O]. Torsional barrier heights associated with the methyl internal rotation for each structure have been computed to evaluate the occurrence of possible A-E splittings in the rotational spectra. For the most stable isomer, CH3PCO, we found a V3 barrier of 82 cm-1, which is slightly larger than that obtained experimentally for the N-counterpart, CH3NCO, yet still very low. Therefore, the analysis of its rotational spectrum can be anticipated as a challenging task owing to the effect of the CH3 internal rotation. The complete set of spectroscopic constants and transition frequencies reported here for the most stable isomer, CH3PCO, is intended to facilitate eventual laboratory searches.

Anxiety levels among health sciences students during their first visit to the dissection room.

BACKGROUND: The teaching of human anatomy is often based on practices of cadaver dissection and prosected specimens. However, exposure to human cadavers might be stressful and anxiety-inducing for students. The aim of this study is to explore the degree of satisfaction and anxiety among first-year students in the Medicine, Occupational Therapy, Speech Therapy and Nursing programmes at the Universidad de Castilla-La Mancha (Spain) who are experiencing their first dissection/prosection practice to develop stress coping strategies. METHODS: A total of 204 health sciences students participated in this study. The State-Trait Anxiety Inventory was used to evaluate anxiety. RESULTS: 'State Anxiety' (SA) decreased significantly throughout the course (p < 0.05), from 20.7 ± 19.29 to 13.7 ± 11.65 points. Statistical differences (p < 0.05) in SA were found between the different health sciences, and pre-practice SA was significantly different from post-practice SA. The students with the highest pre-practice SA levels were nursing students (31.8 ± 33.7 points), but medical students had the highest post-practice SA levels (18.4 ± 12.82 points). CONCLUSIONS: Although students were satisfied with dissection practices (96.8% of them recommended that the practices be retained for future courses), the experience can provoke stressful responses that must be addressed using advanced preparation and coping mechanisms, especially among medical and nursing students.

Alkaline and Alkaline-earth Cyanoacetylides: A Combined Theoretical and Rotational Spectroscopic Investigation.

The metallic cyanoacetylides LiC3N, NaC3N, MgC3N and CaC3N have been investigated by combined spectroscopy measurements and theoretical calculations. The theoretical calculations predict for the four species that the linear isomer with formula MCCCN (M= Li, Na, Mg and Ca) is the most stable one. We used the laser ablation molecular beam Fourier transform microwave spectroscopy to synthesize these species by the reaction of metal vapors, produced by laser ablation, and the 3-bromo-2-propynenitrile (BrCCCN). The pure rotational spectra were observed by Fourier transform microwave spectroscopy in the 2-18 GHz frequency region only for LiCCCN and NaCCCN, while no spectral signatures for MgCCCN and CaCCCN could be detected. Finally, we have searched for LiCCCN and NaCCCN species towards the carbon-rich evolved star IRC + 10216 but only upper limits to their abundances have been obtained.

Structural Trends in Monoboronyl Compounds: Analysis of the Interaction of Second-Row Elements with BO.

A theoretical study of the monoboronyl compounds of second-row elements, [XBO] (X = Na, Si, P, S, Cl), has been carried out. It is observed that the preference for the XBO arrangement is higher when moving to the right of the period. In the case of sodium monoboronyl three minima were characterized, all lying rather close in energy: linear NaBO, linear NaOB, and an L-shaped structure. Linear NaBO and the L-shaped structure are nearly isoenergetic, whereas linear NaOB is located 2.11 kcal/mol above linear NaBO. The barrier for the conversion of the L-shaped structure into linear NaBO is about 5.1 kcal/mol, suggesting that both species could be potential targets for experimental detection. For silicon monoboronyl, two minima, linear SiBO and linear SiOB, are found, the latter lying about 13 kcal/mol above SiBO. The barrier for the isomerization of SiOB into SiBO is estimated to be 11.4 kcal/mol. For phosphorus, sulfur, and chlorine monoboronyls the linear XBO isomer is clearly the most stable one, and the barriers for the conversion into XOB species are relatively high, suggesting that quite likely the linear XBO isomer should be the main experimental target. All studied monoboronyls are relatively stable, with dissociation energies increasing from left to right of the second-row (69.8 kcal/mol for NaBO and 118.98 kcal/mol for ClBO). An analysis of the bonding for second-row monoboronyls has been carried out, emphasizing the different characteristics of the X-B and X-O bonds along the second row.

Metallic monoboronyl compounds: Prediction of their structure and comparison with the cyanide analogues.

A theoretical study of monoboronyls of different metals has been carried out. We have chosen Mg as representative of s-block elements, Al for the p-block, and Group 11 metals (Cu, Ag, and Au) for the d-block. Different behaviors are observed: bonding through the oxygen atom is preferred in the case of Al, for all Group 11 monoboronyls bonding through the boron atom prevails and both interactions give rise to almost isoenergetic compounds in the case of Mg. Predictions for the spectroscopic parameters relevant for rotational and vibrational spectroscopy of the different competitive species are provided. Al and Group 11 boronyls have relatively high dissociation energies, whereas Mg boronyl has moderate dissociation energy. The molecular structure of metal boronyls has been rationalized through an analysis of the bonding. The similarities and differences between metal boronyls and their isoelectronic cyanide analogues have been discussed. © 2017 Wiley Periodicals, Inc.

Metallic cyanoacetylides of copper, silver and gold: generation and structural characterization.

The metallic cyanoacetylides CuCCCN, AgCCCN, and AuCCCN have been synthesized in the throat of a pulsed supersonic expansion by reaction of metal vapors, produced by laser ablation, and BrCCCN. Their pure rotational spectra in the (X1Σ+) electronic ground state were observed by Fourier transform microwave spectroscopy in the 2-10 GHz frequency region. Importantly, the rotational spectroscopy constants determined from the analysis of the rotational spectra clearly established the existence of metal-CCCN arrangements for all the mentioned cyanoacetylides. A study of the chemical bonding by means of a topological analysis of the electron density helps to understand the preference for metal-C bonding over metal-N bonding.

Molecular Structure and Bonding in Plutonium Carbides: A Theoretical Study of PuC3.

The most relevant species of plutonium tricarbide were characterized using theoretical methods. The global minimum is predicted to be a fan structure where the plutonium atom is bonded to a quasi-linear C3 unit. A rhombic isomer, shown to be a bicyclic species with transannular C-C bonding, lies about 39 kJ/mol above the fan isomer. A linear PuCCC isomer and a three-membered ring CPuC2 isomer were found to be higher in energy (150 and 195 kJ/mol, respectively, above the predicted global minimum). The possible processes for the formation of these species are discussed, and the IR spectra were predicted to help in possible experimental detection. The nature of the Pu-C interaction has been analyzed in terms of a topological analysis of the electronic density, showing that Pu-C bonding is essentially ionic with a certain degree of covalent character.

Structure and spectroscopic properties of neutral and cationic tetratomic [C,H,N,Zn] isomers: A theoretical study.

The structure and spectroscopic parameters of the most relevant [C,H,N,Zn] isomers have been studied employing high-level quantum chemical methods. For each isomer, we provide predictions for their molecular structure, thermodynamic stabilities as well as vibrational and rotational spectroscopic parameters which could eventually help in their experimental detection. In addition, we have carried out a detailed study of the bonding situations by means of a topological analysis of the electron density in the framework of the Bader's quantum theory of atoms in molecules. The analysis of the relative stabilities and spectroscopic parameters suggests two linear isomers of the neutral [C,H,N,Zn] composition, namely, cyanidehydridezinc HZnCN ((1)Σ) and hydrideisocyanidezinc HZnNC ((1)Σ), as possible candidates for experimental detections. For the cationic [C,H,N,Zn](+) composition, the most stable isomers are the ion-molecule complexes arising from the direct interaction of the zinc cation with either the nitrogen or carbon atom of either hydrogen cyanide or hydrogen isocyanide, namely, HCNZn(+) ((2)Σ) and HCNZn(+) ((2)Σ).

Halogen-abstraction reactions from chloromethane and bromomethane molecules by alkaline-earth monocations.

The reactions, in the gas phase, between alkali-earth monocations (Mg(+), Ca(+), Sr(+), Ba(+)) and CH3X (X = Cl, Br) have been theoretically studied. The stationary points on the potential energy surfaces were characterized at the Density Functional Theory level on the framework of the mPW1K functional with the QZVPP Ahlrichs's basis sets. A complementary kinetics study has also been performed using conventional/variational microcanonical transition state theory. In the reactions of Mg(+) with either chloro- or bromomethane the transition structure lies in energy clearly above the reactants rendering thermal activation of CH3Cl or CH3Br extremely improbable. The remaining reactions are exothermic and barrierless processes; thus carbon-halogen bonds in chloro- or bromomethane can be activated by calcium, strontium or barium monocations to obtain the metal halogen cation and the methyl radical. The Mulliken population analysis for the stationary points of the potential energy surfaces supports a "harpoon"-like mechanism for the halogen-atom abstraction processes. An analysis of the bonding situation for the stationary points on the potential energy surface has also been performed in the framework of the quantum theory of atoms in molecules.

Generation and structural characterization of aluminum cyanoacetylide.

Combined spectroscopy measurements and theoretical calculations bring to light a first investigation of a metallic cyanoacetylide, AlC3N, using laser ablation molecular beam Fourier transform microwave spectroscopy. This molecule was synthesized in a supersonic expansion by the reaction of aluminum vapour with C3N, produced from solid aluminum rods and BrCCCN in a newly constructed ablation-heating nozzle device. A set of accurate rotational and (27)Al and (14)N nuclear quadrupole coupling constants have been determined from the analysis of the rotational spectrum and compared with those predicted in a high-level ab initio study, conducting to the assignment of the observed species to linear AlCCCN. We have searched for this species towards the carbon-rich evolved star IRC + 10216 but only an upper limit to its abundance has been obtained.

Breast Metastasis From Cutaneous Melanoma: Beyond the Infiltrating Ductal Carcinoma.

Breast metastases of extramammary origin are an extremely rare entity. Solid organ metastases to the breast include malignant melanoma, epithelial carcinoma (adenocarcinoma and squamous cell carcinoma of the lung and gastrointestinal tract), and sarcoma. A breast neoplasm can be caused by a primary tumor, in-transit metastasis, breast metastasis, and skin metastasis. A 42-year-old female patient presented with a hyperpigmented lesion on the first finger of her left hand. An incisional biopsy was carried out, reporting pigmented epithelioid melanoma. Amputation of the finger was performed, as well as an axillary sentinel lymph node excision. Later during the treatment and follow-up by medical oncology, a breast tumor was located, followed by a protocol and the approach of possible differential diagnoses. Finally, it was characterized as metastatic cutaneous melanoma. The therapeutic approach regarding the possible origin of the metastatic neoplastic character of breast tumors culminated in this case in the palliative treatment with immunotherapy of cutaneous malignant melanoma. The diagnosis of breast metastases from cutaneous malignant melanoma is a real challenge, so an extensive history and high clinical suspicion are crucial in order to provide adequate treatment, despite the gloomy prognosis.

Acute Glomerulonephritis as a Paraneoplastic Syndrome Secondary to Urachal Adenocarcinoma: An Unknown Entity.

Urachal carcinoma is an uncommon malignancy with a peculiar biomolecular characterization and therefore a complex approach. It was incorporated by the World Health Organization in 2004 in the tumors of the urinary system classification. This neoplasm is generally diagnosed in advanced stages. The standard treatment is surgical, however, due to the rarity and relatively late clinical manifestation of urachal carcinomas, the survival data are mostly case reports, as well as information about medical-surgical treatment based on evidence. The data used were extracted from both the physical and electronic clinical records. Among atypical presentations reported in the literature, we report a case of urachal adenocarcinoma with simultaneous glomerulonephritis as a paraneoplastic syndrome of which there is no report to date. Surgery was carried out in our patient, unfortunately with lifetime morbidity from kidney function replacement secondary to kidney function damage by glomerulonephritis, despite previous immunosuppression treatment for rapidly progressive glomerulonephritis. It is worth mentioning that if the initial diagnosis represents a clinical challenge, treatment is even more complex, given the little information that currently exists about it. Urachal carcinoma is a diagnostic and treatment challenge. Up to now, surgery has been the treatment of choice in localized or locally advanced disease, however, with a high morbidity for the patient.

Multicenter Study on the Frequency of Low Bone Mineral Density in Young Women With Breast Cancer and Associated Factors.

INTRODUCTION: Young women with breast cancer (BC) may experience bone mineral density (BMD) loss secondary to cancer treatment effects on estrogen levels. Studies assessing BMD in BC patients have had a limited representation of young women. This multicenter retrospective study analyzed the frequency of low BMD and associated factors in this age group. METHODS: Women diagnosed with stage 0-III BC at ≤40 years, treated with chemotherapy and/or endocrine therapy between 2010 and 2020 at 5 Mexican BC referral centers were eligible. Demographic, clinical and treatment data were collected, as well as bone dual-energy X-ray absorptiometry (DEXA) results. Low BMD was defined as lumbar or femoral neck T-score < -1.0 or Z-score ≤ -2.0. RESULTS: A total of 1259 patients were included; median age at diagnosis was 36 years (21-40). Overall, 93% received chemotherapy and 65% endocrine therapy (tamoxifen was received at some point by 61%, aromatase inhibitors by 17%, and GnRH agonists/bilateral oophorectomy by 21%). DEXA scans were documented in 254 (20%), of which 163 (64%; 95% confidence interval [CI] 58%-70%) had a low BMD report. Low BMD was associated with receiving aromatase inhibitors (Odds ratio [OR] 1.92; 95% CI 1.13-3.24), and GnRH agonists/bilateral oophorectomy (OR 2.25; 95% CI 1.21-4.21). CONCLUSION: The suboptimal frequency of BMD monitoring observed displays an alarming disregard for bone health in young patients. Thus, a high proportion of women with low BMD are potentially being missed and precluded from the opportunity to receive timely interventions. Particular focus should be put on BMD monitoring among patients treated with aromatase inhibitors, GnRH agonists or bilateral oophorectomy.

Computational study of peptide bond formation in the gas phase through ion-molecule reactions.

A computational study of peptide bond formation from gas-phase ion-molecule reactions has been carried out. We have considered the reaction between protonated glycine and neutral glycine, as well as the reaction between two neutral glycine molecules for comparison purposes. Two different mechanisms, concerted and stepwise, were studied. Both mechanisms show significant energy barriers for the neutral reaction. The energy requirements for peptide bond formation are considerably reduced upon protonation of one of the glycine molecules. For the reaction between neutral glycine and N-protonated glycine the lowest energy barrier is observed for the concerted mechanism. For the reaction between neutral glycine and protonated glycine at carbonyl oxygen, the preferred mechanism is the stepwise one, with a relatively small energy barrier (23 kJ mol(-1) at 0 K) and leading to the lowest-lying protonated glycylglycine isomer. In the case that the reaction could be initiated by protonated glycine at hydroxyl oxygen the process would be barrier-free and clearly exothermic. In that case peptide bond formation could take place even under interstellar conditions if glycine is present in space.

Kinetics studies of the reactions of main fourth-period monocations (Ga+, Ge+, As+, and Se+) with methyl fluoride.

Thermodynamics and kinetics theoretical studies on the gas-phase reactions of fluoromethane with main fourth-period monocations (Ga(+), Ge(+), As(+), and Se(+)) have been carried out. Density functional theory (in particular mPW1K functional) was employed in the description of the potential energy surfaces, and refinement of the energies were done at the CCSD(T) level. The reaction rate constants were estimated using variational/conventional microcanonical transition state theory. From a thermodynamic viewpoint, the fluorine abstraction product is predicted for Ga(+) and Ge(+), whereas for As(+) and Se(+) the elimination product, MCH2(+) (M = As, Se) + HF, is the preferred one. Nevertheless, the most favorable channel for the reactions of CH3F with Ga(+) and Se(+) cations present a net activation barrier. In the case of Ga(+), the reaction proceeds via an addition channel forming the adduct complex, CH3FGa(+), whereas for Se(+) no reaction is found, in agreement with the experiments. The predicted reaction rate constants are in reasonable good agreement with the experimental values available. Apart from the harpoon-like mechanism, our results suggest that an oxidative addition mechanism seems to play a relevant role.

Reactivity of first-row transition metal monocations (Sc+, Ti+, V+, Zn+) with methyl fluoride: a computational study.

The gas-phase reactivity of methyl fluoride with selected first-row transition metal monocations (Sc(+), Ti(+), V(+), and Zn(+)) has been theoretically investigated. Our thermochemical and kinetics study shows that early transition-metal cations exhibit a much more active chemistry than the latest transition metal monocation Zn(+). The strong C-F bond in methyl fluorine can be activated by scandium, titanium, and vanadium monocations yielding the metal fluorine cation, MF(+). However, the rate efficiencies vary dramatically along the period 0.73 (Sc), 0.91 (Ti), and 0.028 (V) in agreement with the experimental observation. The kinetics results show the relative importance of the entrance and exit channels, apart from the "inner" bottleneck, to control the global rate constant of these reactions. At the mPW1K/QZVPP level our computed kglobal (at 295 K), 1.99 × 10(-9) cm(3) molecule(-1) s(-1) (Sc(+)), 1.29 × 10(-9) cm(3) molecule(-1) s(-1) (Ti(+)), and 3.46 × 10(-10) cm(3) molecule(-1) s(-1) (V(+)) are in good agreement with the experimental data at the same temperature. For the reaction of Zn(+) and CH3F our predicted value for kouter, at 295 K, 3.79 × 10(-9) cm(3) molecule(-1) s(-1), is in accordance with the capture rate constant. Our study suggests that consideration of the lowest excited states for Ti(+) and V(+) is mandatory to reach agreement between calculations and experimental measurements.

Anxiety, emotions, and thoughts of veterinary medicine students during their first visit to the dissection room.

The use of cadavers is essential for veterinary anatomy learning. However, facing an animal corpse can be stressful for veterinary students because of their empathy toward animals. The objective of this study was to evaluate veterinary medicine students' emotions, feelings, and anxiety levels related to practicals with dog cadavers. Two questionnaires were administered to 1st year students (n = 168) at CEU Cardenal Herrera University in Valencia (Spain) before and after their first practical session with cadavers. The application of State-Trait Anxiety Inventory questionnaires showed that "state anxiety" decreased significantly (p < 0.05), from a score of 14.8 before the practical to 10.4 after, and that female students showed higher but not significantly different levels than males. Most (64%) of the students were not willing to donate the bodies of their pets, and those students were more stressed before the practical than their peers, although their anxiety levels significantly decreased by the end of the session. The majority of the students answered positively about emotions, such as feeling calm, safe, not nervous, relaxed and not worried before the practical, and this increased significantly to more than 80% by the end of the session. The visualization of educational videos prior to the session was evaluated positively by students. These results agree with those reported in other health science disciplines, showing that students face practical sessions with corpses in a similar way and suggesting that the use of videos can help decrease anxiety and enhance their learning experience.

Small carbides of third-row main group elements: structure and bonding in C3X compounds (X = K-Br).

The molecular structures of third-row main group tricarbides C(3)X (X = K-Br) have been studied by quantum chemical methods. It is found that less electronegative elements (K, Ca, Ga, Ge) favor either fan or rhombic structures (resulting from side interactions with either linear or triangular C(3) units), whereas the more electronegative elements (As, Se, Br) favor linear or three-membered ring structures (resulting from σ-type interactions with either linear or triangular C(3) units). The predicted global minima are of fan type for C(3)K, rhombic for C(3)Ca, C(3)Ga, and C(3)Ge, linear for C(3)As and C(3)Se, and a three-membered ring for C(3)Br. In order to aid in their possible experimental identification the molecular geometries, vibrational frequencies, IR intensities, and dipole moments have been provided. The nature of the interactions has been characterized through an analysis of the electronic charge density. In addition, the relative stability of the different isomers has been also rationalized in terms of an energy decomposition analysis.

Computational study on the affinity of potential drugs to SARS-CoV-2 main protease.

Herein, we report a computational investigation of the binding affinity of dexamethasone, betamethasone, chloroquine and hydroxychloroquine to SARS-CoV-2 main protease using molecular and quantum mechanics as well as molecular docking methodologies. We aim to provide information on the anti-COVID-19 mechanism of the abovementioned potential drugs against SARS-CoV-2 coronavirus. Hence, the 6w63 structure of the SARS-CoV-2 main protease was selected as potential target site for the docking analysis. The study includes an initial conformational analysis of dexamethasone, betamethasone, chloroquine and hydroxychloroquine. For the most stable conformers, a spectroscopic analysis has been carried out. In addition, global and local reactivity indexes have been calculated to predict the chemical reactivity of these molecules. The molecular docking results indicate that dexamethasone and betamethasone have a higher affinity than chloroquine and hydroxychloroquine for their theoretical 6w63 target. Additionally, dexamethasone and betamethasone show a hydrogen bond with the His41 residue of the 6w63 protein, while the interaction between chloroquine and hydroxychloroquine with this amino acid is weak. Thus, we confirm the importance of His41 amino acid as a target to inhibit the SARS-CoV-2 Mpro activity.

The Effect of Visualization Techniques on Students of Occupational Therapy during the First Visit to the Dissection Room.

Background: Part of the basic teaching of human anatomy are prosection sessions with a human corpse, which may generate stress or anxiety among students. The objective of this work was to study how, through the visualization technique (a coping technique), these levels could be reduced before starting prosection classes. Methods: A cross-sectional pilot study was conducted involving first-year students who had never participated in screening sessions. Prior to the visit, occupational therapy students underwent a viewing session (visualization technique). On the day of the visit, before and after the screening session, an anonymous questionnaire was distributed to find out about aspects of the students' experiences, such as their feelings and perceptions. The State−Trait Anxiety Inventory was used to assess anxiety. Results: The baseline levels of anxiety measured remained stable (from 18.5 to 18.2 points), with no differences being found (p > 0.05). The levels of emotional anxiety measured fell from 15.2 to 12.6 points (p < 0.05). Before starting the class, there were six students (17.1%) with anxiety criteria, and this figure was doubled at the end of the session (33.3%) (p < 0.05). Conclusions: Sessions in a dissection room can cause stressful experiences and change the emotional balances of some students. The results obtained and published here showed no significant differences after the visualization technique. We found that the students believed that the prosection sessions were very useful for teaching anatomy.