Reversible Capture Mechanism of CO2 as a Zn(II)-Methylcarbonate.

In this study, we elucidate the reaction mechanism for capturing CO2 with the ZnL1(MeOH) complex (L1=diacetyl-2-(4-methyl-3-thiosemicarbazone)-3-(2-hydrazinatopyridine)) in a methanol solution, using density functional theory calculations. One pathway involves the protonation of ZnL1(MeOH) by methylcarbonic acid, followed by ligand exchange of MeOH with MeOCO2 -. An alternative mechanism suggests a tautomerization between ZnL1(MeOH) and Zn(HL1)(OMe), followed by CO2 insertion. The latter pathway is energetically more favorable than the former and more complex than initially proposed. In fact, we unveiled that the solvent catalyzes tautomerization, as one explicit methanol molecule acts as a proton transfer agent. Then, Zn(HL1)(OMe) captures CO2, yielding a methylcarbonate bound to the metal center. The final step involves a rearrangement that leads to the cleavage of the Zn-O(Me)(COO) bond and the formation of a new Zn-O(COOMe) bond, along with the rotation of the methylcarbonate group. We consider an additional mechanism that combines tautomerization and ligand exchange but is endergonic and requires a high activation barrier for the ligand exchange. Furthermore, we evaluate the ligand basicity through the pKa calculated values of the Zn(II) complexes, the effects of varying the ligand from 4-methyl-thiosemicarbazone to 4-ethyl (L2), 4-phenethyl (L3), and 4-benzyl (L4) derivatives, and reversibility of the reaction in an argon environment.

Breaking the plane: B5H5 is a three-dimensional structure.

In this study, we delved into the structure of B5H5 and questioned some of its accepted assumptions. By exploring the potential energy surface, we found a new three-dimensional structure as the global minimum. This finding is in contrast with the previously hypothesized planar and cage-like models. Our exploration extends to the kinetic stability of various B5H5 isomers, offering insights into the dynamic behavior of these molecules.

Unveiling the electronic and structural consequences of removing two electrons from B12H122.

The notion that a regular icosahedron is unattainable in neutral B12H12 has persisted for nearly 70 years. This is because 24 valence electrons are used for B-H bonds, while another 24 electrons are necessary to maintain the deltahedron, unlike the 26 used in the dianion. According to Wade-Mingos rules, the neutral system should be a deltahedron with a capped face. Nevertheless, our exploration of the potential energy surface of B12H12 reveals that the global minimum is a closed-shell form with an H2 unit attached to a boron vertex of B12H10, preserving the deltahedral boron skeleton.

Impact of Care Interventions on the Survival of Patients with Cardiac Chest Pain.

BACKGROUND: Chest pain is considered the second most frequent complaint among patients seeking emergency services. However, there is limited information in the literature about how the care provided to patients with chest pain, when being attended to in the emergency room, influences their clinical outcomes. AIMS: To assess the relationship between care interventions performed on patients with cardiac chest pain and their immediate and late clinical outcomes and to identify which care interventions were essential to survival. METHODS: In this retrospective study. We analyzed 153 medical records of patients presenting with chest pain at an emergency service center, São Paulo, Brazil. Participants were divided into two groups: (G1) remained hospitalized for a maximum of 24 h and (G2) remained hospitalized for between 25 h and 30 days. RESULTS: Most of the participants were male 99 (64.7%), with a mean age of 63.2 years. The interventions central venous catheter, non-invasive blood pressure monitoring, pulse oximetry, and monitoring peripheral perfusion were commonly associated with survival at 24 h and 30 days. Advanced cardiovascular life support and basic support life (p = 0.0145; OR = 8053; 95% CI = 1385-46,833), blood transfusion (p < 0.0077; OR = 34,367; 95% CI = 6489-182,106), central venous catheter (p < 0.0001; OR = 7.69: 95% CI 1853-31,905), and monitoring peripheral perfusion (p < 0.0001; OR = 6835; 95% CI 1349-34,634) were independently associated with survival at 30 days by Cox Regression. CONCLUSIONS: Even though there have been many technological advances over the past decades, this study demonstrated that immediate and long-term survival depended on interventions received in an emergency room for many patients.

Bacillary Layer Detachment in an Atypical Case of Central Serous Chorioretinopathy Associated with High Hyperopia.

A 16-year-old boy with elevated hyperopia presented to the office with a 24-h history of bilateral blurred vision, mainly of the left eye, and bilateral central serous chorioretinopathy. He showed a clinically recognizable bacillary layer detachment in one eye and excellent multimodal diagnostic image correlation, with the best-corrected visual acuity as 20/400. He had bilateral serous retinal detachment, as confirmed by optical coherence tomography. Laser photocoagulation was performed with good results, and reestablishment of the foveal anatomical structure was documented 16 days after treatment.

Microwave-enhanced synthesis of 26-amino-22-oxocholestanes and their cytotoxic activity.

The synthesis of a series of 26-amino-22-oxocholestanes derived from diosgenin was accomplished via the substitution of an iodine atom at C-26 by primary and secondary amines. The reactions were conducted in refluxing acetonitrile and through microwave-assisted heating. The latter shows significant improvements in terms of reaction times going from hours to a few minutes or even seconds for completion. Only one of the selected amines, 4-aminourazole, did not yield the substitution product and the imine formation pathway was investigated instead, achieving the 26-iminourazole-22-oxocholestane. All the final products have been characterized and the cytotoxic activity of three of them has been evaluated in SiHa, MCF-7 and MDA tumor cell lines by the sulforhodamine B assay.

Nursing workload. Calculation of cardiovascular risk and therapeutic objectives. / Carga de enfermedad. Cálculo del riesgo cardiovascular y objetivos terapéuticos.

Therapeutic intervention should be determined by the risk of developing atheromatous cardiovascular disease (CVD). The higher the risk, the more intense the action should be. This is the reason for the stratification of patient risk. In primary prevention, the two main guidelines used, the American Heart Association and the American College of Cardiology (ACC/AHA) use the Pooled cohort equations (PCE) and the guidelines of the European societies use the SCORE tables. The PCE calculates the risk of fatal and non-fatal CVD, and the SCORE calculates risk of fatal CVD only. In young people, it is useful to consider the lifetime risk calculation. The Spanish Society of Arteriosclerosis (SEA) recommends the SCORE system in Spain. SCORE and PCE calculate the risk for people up to 70 and 75 years of age. Prediction and potentials are available for 80 years of age and above, with the data available being much more scarce. Risk stratification in secondary prevention may be useful to identify the subgroup of patients who may benefit from more intensive treatment. Imaging tests, especially coronary calcium scans and vascular ultrasound, can help to better the profile risk. European guidelines identify LDL cholesterol as a therapeutic target. They recommend initiating treatment with statins, and increasing dose and potency until targets are achieved, and then to treatment with potent statins at a maximum tolerated dose, and ezetimibe if targets are not achieved. As a third step, PCSK9 inhibitors are indicated. They set very ambitious targets, as low as 40 mg/dL in those subjects with recurrences before two years of CVD despite high-intensity statin therapy, and below 55 mg/dL for all very high-risk subjects.

The curriculum of the plague.

The Covid-19 pandemic can be read as an eruption of the Real: a traumatic event that overwhelms our capacity for symbolization and exposes the fragility of the imaginary. Albert Camus addresses this traumatic dimension in his 1947 novel The Plague, in which he reserves a rather puzzling statement for the closing paragraph: A plague never disappears, he wrote, but can lie dormant only to reappear once again "for the education of men". What lessons can be learned from the pandemic we are experiencing right now? While Covid-19 is often discussed from a biological perspective, the magnitude of the tragedy raises questions far beyond the confines of the natural/medical sciences, questions about humanity, our limits and possibilities, and the transcendent. This article explores the potential educational aspect of the pandemic by framing the discussion in an exegetical reading of Camus' novel. Through this reading, it claims that even within the tragic reality of its effects, the present pandemic might bring to the fore the notion of an existential kind of learning-one that is deeply personal, that cannot be programmed or learned from direct teaching, and that connects us in relevant ways to the lives of others. At the same time, this reading is not oblivious to the practical needs around decision-making on the part of educational policymakers, administrators, and teachers. As the novel shows, tragic events create a demand for quick action, so a few practical principles for curriculum decision-making are also offered.

Impacto da doença valvar nas atividades cotidianas de pacientes no período pré-operatório / Impact of valvular heart disease on activities of daily living during the preoperative period

Objetivo: avaliar o impacto da valvopatia no cotidiano dos pacientes em pré-operatório de cirurgia cardíaca. Métodos: estudo transversal, observacional, descritivo, com amostra de conveniência. Utilizado o instrumento "Impacto da Doença no Cotidiano do Valvopata", composto por uma questão geral e 14 itens, distribuídos em quatro domínios: "Impacto físico da doença", "Impacto da doença nas atividades cotidianas", "Impacto social e emocional da doença" e "Adaptação à doença". Obtém-se um escore para cada domínio e um escore total, por meio da soma de todos os escores (14 a 350), quanto maior o valor, maior a percepção negativa do impacto. Resultados: participaram do estudo 73 pacientes. O domínio "Impacto da doença nas atividades cotidianas" apresentou a maior média (82,79; DP=21,35), seguido pelo "Impacto social e emocional da doença" (61,24; DP=22,7). A média do escore total foi 210,55 (DP=51,7). Conclusão: os pacientes avaliaram o impacto da valvopatia como negativo no pré-operatório de cirurgia cardíaca.

Objective: to assess the impact of valvular heart disease on the daily life of patients in the preoperative period of heart surgery. Methods: we conducted a descriptive cross-sectional study using consecutive sampling. We used the assessment instrument "Impact of Valvular Heart Disease on the Daily Life of Patients", consisting of 14 items divided into four domains: "Physical impact - symptoms", "Impact on activities of daily living", "Social and emotional impact" and "Adaptation to the disease". Each domain is scored and an overall score is calculated based on the sum of all items, ranging from 14 to 350. The higher the score, the more negative the perceived impact. Results: 73 patients participated in the study. The domain that obtained the highest mean score was "Impact on activities of daily living" (82.79; SD = 21.35), followed by "Social and emotional impact" (61.24; SD = 22.7). The mean overall score was 210.55 (SD = 51.7). Conclusion: the patients rated the impact of valvular heart disease during the preoperative period of heart surgery as negative.

trans-Hydroboration-oxidation products in Δ5-steroids via a hydroboration-retro-hydroboration mechanism.

Herein, we report for the first time a "trans-hydroboration-oxidation product" isolated and characterized under traditional hydroboration-oxidation conditions using cholesterol and diosgenin as substrates. These substrates are excellent starting materials because of the rigidity and different structural environments around the double bond. Further investigations based on experimental evidence, in conjunction with theoretical studies, indicate that the formation of this trans-species occurs via a retro-hydroboration of the major product to generate the corresponding Δ6-structure and the subsequent hydroboration by the ß-face. Besides, the corresponding Markovnikov type products have been isolated in synthetically useful yields. The behavior of the reaction under a range of temperatures is also investigated.

Seagrass Halodule wrightii as a new habitat for the amphioxus Branchiostoma californiense (Cephalochordata, Branchiostomidae) in the southern Gulf of California, Mexico.

The first record of the amphioxus Branchiostoma californiense on seagrass patches of Halodule wrightii in the Gulf of California is reported. Sixty individuals (19 males, 18 females, and 23 undifferentiated) were collected in May 2017 at Bahía Balandra, Gulf of California, from subtidal seagrass patches at a depth of 0.5 m at low tide. The length and weight ranged from 15.88-28.44 mm and from 0.01-0.11 g for females and 11.7-27.9 mm and 0.01-0.09 g for males, respectively. The minimum size of sexually mature individuals was 11.70 mm for males and 15.88 mm for females; 62% of the specimens were sexually mature. Analysis of the total length-weight relationship suggested an allometric growth pattern among females, males and undifferentiated individuals, whereas an analysis of the entire sample suggested an isometric growth pattern. Typical and additional morphological characters were used to identify the amphioxi. High morphological variability between individuals was found, suggesting the presence of several morphotypes. Branchiostoma californiense had been previously reported as exclusively associated with bare sandy areas, but our study shows that this species can also be found in seagrass patches, using them as breeding and feeding grounds. Thus, seagrass patches are evidenced as suitable habitats for amphioxus.

Origin of the isotropic motion in crystalline molecular rotors with carbazole stators.

Herein we report two crystalline molecular rotors 1 and 4 that show extremely narrow signals in deuterium solid-state NMR spectroscopy. Although this line shape is typically associated with fast-moving molecular components, our VT 2H NMR experiments, along with X-ray diffraction analyses and periodic DFT computations show that this spectroscopic feature can also be originated from low-frequency intramolecular rotations of the central phenylene with a cone angle of 54.7° that is attained by the cooperative motion of the entire structure that distorts the molecular axis to rotation. In contrast, two isomeric structures (2 and 3) do not show a noticeable intramolecular rotation, because their crystallographic arrays showed very restricting close contacts. Our findings clearly indicate that the multiple components and phase transitions in crystalline molecular machines can work in concert to achieve the desired motion.

Revisiting the Formation Mechanism of 1,3,4-Oxadiazole-2(3 H)-ones from Hydrazonyl Chloride and Carbon Dioxide.

The reaction mechanism for the synthesis of 1,3,4-oxadiazole-2(3 H)-ones from hydrazonyl chloride and CO2 in the presence of CsF/18-crown-6 and toluene, is revisited via density functional theory computations. Although this reaction was earlier classified as a 1,3-dipolar cycloaddition, we found some competing pathways involved therein. The mechanisms including the (F-CO2)- anion and the nitrile imine intermediate are some options. The dimerization of nitrile imine is another competing mechanism in this reaction. Our results show that the most favorable mechanism proceeds via a stepwise pathway without involving any nitrile imine intermediate or the (F-CO2)- anion. The F- anion, resulting from the formation of a complex between 18-crown-6 and Cs+ cation, deprotonates the nitrile imine precursor easily, which acts then as a nucleophilic anion, enhancing the reactivity of CO2 toward it. The mechanism for the reaction with COS, an isoelectronic analogue of CO2, is also explored.

Bonding and Mobility of Alkali Metals in Helicenes.

In this work, we analyze the interactions of alkali metal cations with [6]- and [14]helicene and the cation mobility of therein. We found that the distortion of the carbon skeleton is the reason that some of the structures which are local minima for the smallest cations are not energetically stable for K+ , Rb+ , and Cs+ . Also, the most favorable complexes are those where the cation is interacting with two rings forming a metallocene-like structure, except for the largest cation Cs+ , where the distortion provoked by the size of the cation destabilizes the complex. As far as mobility is concerned, the smallest cations, particularly Na+ , are the ones that can move most efficiently. In [6]helicene, the mobility is limited by the capture of the cation forming the metallocene-like structure. In larger helicenes, the energy barriers for the cation to move are similar both inside and outside the helix. However, complexes with the cation between two layers are more energetically favored so that the movement will be preferred in that region. The bonding analysis reveals that interactions with no less than 50 % of orbital contribution are taking place for the series of E+ -[6]helicene. Particularly, the complexes of Li+ show remarkable orbital character (72.5-81.6 %).

Revisiting the racemization mechanism of helicenes.

Herein we propose a general mechanism for the racemization of [n]helicenes up to n = 24. It is a concerted process for n = 4-7, but a multi-step mechanism is followed for n≥ 8, involving 2n- 14 intermediates. The changes in the barriers are a delicate consequence of the steric hindrance and the π-interactions.

Does H4SO5 exist?

The possible existence of H4SO5 in aqueous sulfuric acid is analyzed in detail. For bare H4SO5, the computed free energy barrier for the exergonic transformation of H4SO5 into the H2SO4H2O complex is only 3.8 kcal mol-1. The presence of water or sulfuric acid catalyzes the dehydration to such an extent that it becomes almost a barrierless process. In the gas phase, dehydration of H4SO5 is an autocatalytic reaction as the water molecule produced by the decomposition of one H4SO5 molecule induces further dissociation. Thus, in solution, the surrounding water molecules make the para-sulfuric acid a very vulnerable species to exist. The simulated Raman spectra also corroborate the absence of H4SO5 in solution.