Devastating Neurological Outcome Following a Subarachnoid-Pleural Fistula During Thoracic Surgery.

Pneumocephalus due to a subarachnoid-pleural fistula (SPF) has previously been described in the literature and is a rare complication following thoracic surgery. In this report, we discuss a patient who developed profound neurologic sequelae following right-sided pneumonectomy which was complicated by T2 nerve root avulsion and SPF development. The patient returned to the OR on postoperative day 21 in the setting of significant neurologic deterioration secondary to intracranial hypotension and pneumocephalus for SPF closure via thoracic laminectomy in the prone position. We present a rare cause of pneumocephalus and CSF leak, resulting in complications and sequelae and its management.

Development and Validation of Fast and Sensitive RP-HPLC Stability-Indicating Method for Quantification of Piroxicam in Bulk Drug.

A simple, rapid, sensitive, and cost-effective green solvent-assisted reverse-phase high-performance liquid chromatographic technique, coupled with a photodiode array detector, was developed and validated for the estimation of piroxicam (PRXM). The chromatographic separation was achieved by using a C-18 (250 × 4.6) mm, 5-µm stationary phase and a mobile phase consisting of methanol and 0.1% ortho-phosphoric acid in water in a ratio of (80:20) v/v at a flow rate of 1 ml/min. The detection was carried out at a wavelength of 254 nm with a constant injection volume of 10 µL throughout the analysis. The calibration curve was observed to be linear over the optimum concentration range of 50-300 µg mL-1, with an R2 value of 0.9995. The developed method was validated as per the International Council for Harmonisation (ICH) Q2 (R1) guideline. Various parameters like selectivity/specificity, accuracy/recovery, linearity, precision, detection limit, quantitation limit, robustness and stability of analyte in solution were performed for the method validation. The PRXM was evaluated under stressed conditions, including acidic, basic, oxidative, thermal and photolytic, as per ICH Q1 (R2) guidelines. Significant degradation was observed in acidic and basic degradation conditions. Conversely, the drug substance showed stability when exposed to oxidative, photolytic and thermal degradation conditions.

Alternate Electrode Placements to Facilitate Frontal Electroencephalography Monitoring in Anesthetized and Critically Ill Patients.

BACKGROUND: Frontal electroencephalography (EEG) monitoring can be useful in guiding the titration of anesthetics, but it is not always feasible to place electrodes in the standard configuration in some circumstances, including during neurosurgery. This study compares 5 alternate configurations of the Masimo Sedline Sensor. METHODS: Ten stably sedated patients in the intensive care unit were recruited. Frontal EEG was monitored in the standard configuration (bifrontal upright) and 5 alternate configurations: bifrontal inverse, infraorbital, lateral upright, lateral inverse, and semilateral. Average power spectral densities (PSDs) with 95% CIs in the alternate configurations were compared to PSDs in the standard configuration. Two-one-sided-testing with Wilcoxon signed-rank tests assessed equivalence in the spectral edge frequency (SEF-95), EEG power, and relative delta (0.5 to 3.5 Hz), alpha (8 to 12 Hz), and beta (20 to 30 Hz) power between each alternate and standard configurations. RESULTS: After the removal of unanalyzable tracings, 7 patients were included for analysis in the infraorbital configuration and 9 in all other configurations. In the lateral upright and lateral inverse configurations, PSDs significantly differed from the standard configuration within the 15 to 20 Hz band. The greatest decrease in EEG power was in the lateral inverse configuration (median: -97 dB; IQR: -130, -62 dB). The largest change in frequency distribution of EEG power was in the infraorbital configuration; median SEF-95 change of -1.4 Hz (IQR: -2.8, 0.7 Hz), median relative delta power change of +7.3% (IQR: 1.4%, 7.9%), and median relative alpha power change of -0.6% (IQR: -5.7%, 0.0%). CONCLUSIONS: These 5 alternate Sedline electrode configurations are suitable options for monitoring frontal EEG when the standard configuration is not possible.

Bibliometric review of telematics-based automobile insurance: Mapping the landscape of research and knowledge.

Telematics technology and its implementation in auto insurance have received great interest due to their potential to transform the insurance sector and promote safer driving practices. By implementing telematics technology, insurers may tailor insurance premiums to individual drivers, taking into account their real driving habits and performance, ultimately leading to improved road safety, cost savings, and an empowered driving community. The current study, through bibliometric analysis, carefully identifies and evaluates the existing body of scholarly literature on this subject for the last 21 years, including journal articles, conference papers, and related publications. The analysis uncovers key research studies, influential authors, top publication outlets, top countries with collaborations, and prolific research fields, providing useful insights into the evolution and growth of telematics-based insurance research. Furthermore, thematic mapping, cluster analysis, and critical analysis of top recent studies aided in identifying key research clusters and themes, as well as potential gaps and areas for further exploration, guiding future researchers and policymakers in advancing this transformative technology.

Region of interest focused MRI to synthetic CT translation using regression and segmentation multi-task network.

Objective. In MR-only clinical workflow, replacing CT with MR image is of advantage for workflow efficiency and reduces radiation to the patient. An important step required to eliminate CT scan from the workflow is to generate the information provided by CT via an MR image. In this work, we aim to demonstrate a method to generate accurate synthetic CT (sCT) from an MR image to suit the radiation therapy (RT) treatment planning workflow. We show the feasibility of the method and make way for a broader clinical evaluation.Approach. We present a machine learning method for sCT generation from zero-echo-time (ZTE) MRI aimed at structural and quantitative accuracies of the image, with a particular focus on the accurate bone density value prediction. The misestimation of bone density in the radiation path could lead to unintended dose delivery to the target volume and results in suboptimal treatment outcome. We propose a loss function that favors a spatially sparse bone region in the image. We harness the ability of the multi-task network to produce correlated outputs as a framework to enable localization of region of interest (RoI) via segmentation, emphasize regression of values within RoI and still retain the overall accuracy via global regression. The network is optimized by a composite loss function that combines a dedicated loss from each task.Main results. We have included 54 brain patient images in this study and tested the sCT images against reference CT on a subset of 20 cases. A pilot dose evaluation was performed on 9 of the 20 test cases to demonstrate the viability of the generated sCT in RT planning. The average quantitative metrics produced by the proposed method over the test set were-(a) mean absolute error (MAE) of 70 ± 8.6 HU; (b) peak signal-to-noise ratio (PSNR) of 29.4 ± 2.8 dB; structural similarity metric (SSIM) of 0.95 ± 0.02; and (d) Dice coefficient of the body region of 0.984 ± 0.Significance. We demonstrate that the proposed method generates sCT images that resemble visual characteristics of a real CT image and has a quantitative accuracy that suits RT dose planning application. We compare the dose calculation from the proposed sCT and the real CT in a radiation therapy treatment planning setup and show that sCT based planning falls within 0.5% target dose error. The method presented here with an initial dose evaluation makes an encouraging precursor to a broader clinical evaluation of sCT based RT planning on different anatomical regions.

Comparative Study of Gabapentin, Clonidine and Placebo in Alleviating the Hemodynamic Changes Due to Tracheal Intubation and Laryngoscopy.

INTRODUCTION: Hemodynamic changes during laryngoscopy and tracheal intubation must be reduced for safe and effective anesthesia. The present study was conducted to compare the efficacy of oral clonidine, gabapentin and placebo in alleviating the hemodynamic changes due to tracheal intubation and laryngoscopy. METHODS: This was a double-blinded randomized controlled trial conducted on 90 patients who were undergoing elective surgery and were randomized into three groups. Group I (n=30) received a placebo, group II (n=30) received gabapentin and group III (n=30) received clonidine as premedication before anesthesia induction. Patient heart rate and pressor response were recorded periodically and compared between the groups. RESULTS: There was no significant difference in the baseline heart rate (HR) and mean arterial pressure (MAP) between the groups. HR elevation was observed in all three groups and found to be significant (p=0.0001) but the increase was higher in the placebo (15 min: 80.80± 15.41) and lower in the clonidine group (15 min: 65.53± 12.43). The elevation in systolic and diastolic blood pressure was least and transient in the gabapentin group, as compared to placebo and clonidine group. Intra-operatively, the requirement of opioids was higher in the placebo as compared to clonidine and gabapentin (p < .001). CONCLUSION: Clonidine and gabapentin were effective in reducing the hemodynamic changes during laryngoscopy and intubation.

Folate derivatives, 5-methyltetrahydrofolate and 10-formyltetrahydrofolate, protect BEAS-2B cells from high glucose-induced oxidative stress and inflammation.

Folate (vitamin B9) and its biologically active derivatives are well-known antioxidant molecules protecting cells from oxidative degradation. The presence of high glucose, often found in diabetic patients, causes oxidative stress resulting in cellular stress and inflammatory injury. Cells in organs such as the lung are highly prone to inflammation, and various protective mechanisms exist to prevent the progressive disorders arising from inflammation. In the present study, the synthetic form of folate, i.e. folic acid, and active forms of folate, i.e. 5-methyltetrahydrofolate and 10-formyltetrahydrofolate, were evaluated for their antioxidant and antiinflammatory potential against high glucose (50 mM)-mediated oxidative stress and inflammation in BEAS-2B cells, an immortalised bronchial epithelial cell line. High glucose treatment showed a 67% reduction in the viability of BEAS-2B cells, which was restored to the viability levels seen in control cultures by the addition of active folate derivatives to the culture media. The DCFH-DA fluorometric assay was performed for oxidative stress detection. The high glucose-treated cells showed a significantly higher fluorescence intensity (1.81- and 3.8-fold for microplate assay and microscopic observation, respectively), which was normalised to control levels on supplementation with active folate derivatives. The proinflammatory NF-κB p50 protein expression in the active folate derivative-supplemented high glucose-treated cells was significantly lower compared to the folic acid treatment. In support of these findings, in silico microarray GENVESTIGATOR database analysis showed that in bronchiolar small airway epithelial cells exposed to inflammatory condition, folate utilization pathway genes are largely downregulated. However, the folate-binding protein gene, which encodes to the folate receptor 1 (FOLR1), is significantly upregulated, suggesting a high demand for folate by these cells  in inflammatory situations. Supplementation of the active folate derivatives 5-methyltetrahydrofolate and 10-formyltetrahydrofolate resulted in significantly higher protection over the folic acid from high glucose-induced oxidative stress and inflammation. Therefore, the biologically active folate derivatives could be a suitable alternative over the folic acid for alleviating inflammatory injury-causing oxidative stress.

High-Spin Superatom Stabilized by Dual Subshell Filling.

Quantum confinement in small symmetric clusters leads to the bunching of electronic states into closely packed shells, enabling the classification of clusters with well-defined valences as superatoms. Like atoms, superatomic clusters with filled shells exhibit enhanced electronic stability. Here, we show that octahedral transition-metal chalcogenide clusters can achieve filled shell electronic configurations when they have 100 valence electrons in 50 orbitals or 114 valence electrons in 57 orbitals. While these stable clusters are intrinsically diamagnetic, we use our understanding of their electronic structures to theoretically predict that a cluster with 107 valence electrons would uniquely combine high stability and high-spin magnetic moment, attained by filling a majority subshell of 57 electrons and a minority subshell of 50 electrons. We experimentally demonstrate this predicted stability, high-spin magnetic moment (S = 7/2), and fully delocalized electronic structure in a new cluster, [NEt4]5[Fe6S8(CN)6]. This work presents the first computational and experimental demonstration of the importance of dual subshell filling in transition-metal chalcogenide clusters.

Improvement in vitamin B12 status of Wistar rats by supplementing the diet with Chlorella vulgaris biomass.

The sources of bioavailable vitamin B12 are limited, and most of them are animal-derived. Chlorella vulgaris, a freshwater microalga, is known for immune system boosting, nutraceutical properties and presence of a natural form of vitamin B12. The present study focused on the in vivo evaluation of the Chlorella biomass as a source of bioavailable vitamin B12 to alleviate the vitamin B12 deficiency status of Wistar rats. Experimental animals were evaluated for the vitamin B12 deficiency-related circulatory marker (serum vitamin B12) and functional markers (plasma homocysteine and urinary methylmalonic acid), haematological and histological changes. The results showed that an increase of 2.4-fold in urinary methylmalonic acid (13.01 ± 0.89 µmoles moles of creatinine-1), 2.6-fold in plasma homocysteine (17.18 ± 3.57 µmole L-1), and 48% decrease in serum vitamin B12 levels (252.69 ± 1.46 pg mL-1) in vitamin B12 deficient group compared to control animals. The Chlorella biomass supplementation in the diet led to the restoration of the functional and circulatory markers, hematological parameters, and vitamin B12 content of kidney and liver to control levels. The Chlorella biomass supplementation increased the erythrocyte precursors and MAST cells in the bone marrow and also normalized the histological features of kidney, liver, and lung tissues. The results suggest that the vitamin B12 from the Chlorella biomass was bioavailable and facilitated the improvement of vitamin B12 status in deficient rats.

A ligand-induced homojunction between aluminum-based superatomic clusters.

A superatomic molecule formed by joining two metallic clusters linked by an organometallic bridge can behave like a semiconductor and the addition of ligands can induce a significant energy level shift across an inter-cluster homojunction. This shift is induced by the N-ethyl-2-pyrrolidone ligands, and the placement of the ligands strongly affects the direction of the dipole moment, including the case where the dipole moment is parallel to the cluster interface. This computational study provides an alternative strategy for constructing nanometer-scale electronic interfaces between clusters mimicking semiconductor motifs. The semiconducting features in the PAl12 clusters emerge from the grouping of the quantum states in a confined nearly free electron gas that creates a substantial energy gap. An organometallic Ge(CH3)2(CH2)2 bridge links the clusters while maintaining the cluster's electronic shell structure. The amount of level shifting between the bridged clusters can be changed by controlling the number of ligands. Attaching multiple ligands can result in a broken gap energy alignment in which the HOMO level of one cluster is aligned with the LUMO level of the other bridged cluster. Furthermore, the singly ligated bridged superatomic molecule is found to exhibit promising features to separate the electron-hole pairs for photovoltaic applications.

Superatomic molecules with internal electric fields for light harvesting.

Traditional p-n junctions used for photovoltaics require an interface where a light induced electron-hole pair is separated by an electric field. Developing alternative strategies for forming strong internal electric fields for electron-hole pair separation offers the possibility for better performance. We demonstrate that fusing two superatomic clusters with donor/acceptor ligands on opposite sides of the cluster leads to such a strong internal electric field. In two fused metal-chalcogenide Re6S8Cl2(L)4 clusters with donor PMe3 ligands and acceptor CO ligands on the opposite sides of the fused clusters, the electronic levels undergo shifts analogous to band bending in traditional p-n junctions. The fused cluster has a large dipole moment, and an optical spectrum that strongly absorbs excitation above the HOMO-LUMO gap of the fused clusters, but is optically very weak for the lowest energy excitation that can lead to electron-hole pair recombination. This is because the electron is localized on the CO portion of the fused cluster, while the electron-hole pair is localized on the PMe3 side of the cluster. It is shown that the electronic states localized on each side of the cluster can be aligned/misaligned by applying a voltage in different directions, offering diode like characteristics.

Comparative life cycle assessment of autotrophic cultivation of Scenedesmus dimorphus in raceway pond coupled to biodiesel and biogas production.

Life cycle assessment (LCA) of indigenous freshwater microalgae, Scenedesmus dimorphus, cultivation in open raceway pond and its conversion to biodiesel and biogas were carried out. The LCA inventory inputs for the biogas scenario was entirely based on primary data obtained from algal cultivation (in pilot scale raceway pond), harvesting, and biogas production; while only the downstream processing involved in biodiesel production namely drying, reaction and purification were based on secondary data. Overall, eight scenarios were modeled for the integrated process involving: algae-based CO2 capture and downstream processing scenarios for biodiesel and biogas along with impact assessment of nutrient addition and extent of recycling in a life cycle perspective. The LCA results indicated a huge energy deficit and net CO2 negative in terms of CO2 capture for both the biodiesel and biogas scenarios, majorly due to lower algal biomass productivity and higher energy requirements for culture mixing. The sensitivity analysis indicated that variability in the biomass productivity has predominant effect on the primary energy demand and global warming potential (GWP, kg CO2 eq.) followed by specific energy consumption for mixing algal culture. Furthermore, the LCA results indicated that biogas conversion route from microalgae was more energy efficient and sustainable than the biodiesel route. The overall findings of the study suggested that microalgae-mediated CO2 capture and conversion to biodiesel and biogas production can be energy efficient at higher biomass productivity (> 10 g m-2 day-1) and via employing energy-efficient systems for culture mixing (< 2 W m-3).

Effect of Pregabalin on Postcraniotomy Pain in Patients Undergoing Supratentorial Tumor Surgery: A Randomized, Double-Blind, Placebo-Controlled Trial.

Background and Objectives Suboptimal management of postcraniotomy pain causes sympathetic and hemodynamic perturbations, leading to deleterious effects on the neurological system and overall patient outcome. Opioids are the mainstay of postoperative pain management but have various problems when given in high doses, or for prolonged durations in neurosurgical patients. The ideal method of pain control following craniotomy generally relies on a combination of various drugs. Oral pregabalin may be an attractive alternative in these patients. Materials and Methods Sixty, American Society of Anesthesiologists class I and II patients posted for elective supratentorial craniotomy, aged 18 and 60 years, were randomly assigned into three groups of 20 each to receive oral placebo (Group A), pregabalin 75 mg (Group B), or pregabalin 150 mg (Group C) before the induction of anesthesia. At the end of the surgery, patient-controlled analgesia was started with intravenous fentanyl. Visual analog scale (VAS) score was recorded every 2 hours for 24 hours, along with total postoperative fentanyl requirement. Results There were no differences in sex, duration of surgery or anesthesia and total intraoperative fentanyl administered among the three groups. The median postoperative VAS score (Group A-18.0, Group B-20, and Group C-22.0; p = 0.63) was similar in all the groups. However, postoperative fentanyl requirement over 24 hours was least in the group that received 150 mg pregabalin (Group A-190 µg, Group B-240 µg, and Group C-100 µg; p = 0.03). Conclusions Even though pain scores were not significantly different, patients receiving 150 mg oral pregabalin required the least amount of postoperative opioids.

Improvement of vitamin B12 status with Spirulina supplementation in Wistar rats validated through functional and circulatory markers.

Spirulina evaluated as a source of vitamin B12 through the modulation of vitamin B12 deficiency mediated physiological and biochemical changes in experimental animals. The B12 deficient male weanling Wistar rats were fed with Spirulina-supplemented diet for 10 weeks. An increase in urinary methylmalonic acid (22.70 ± 4.08 µmol/moles of creatinine) and plasma homocysteine (16.55 ± 0.48 µmol/L) levels in the B12 deficient group was observed, while these were equal to control in the Spirulina fed group (8.71 ± 0.48 µmol/mol of creatinine and 6.88 ± 1.18 µmol/L, respectively). The vitamin B12 levels in serum (874.27 ± 89.69), plasma (615.53 ± 26.5 pg/ml), kidney (10.19 ± 1.066 ng/g), and liver tissues (6.37 ± 0.62 ng/g) in the Spirulina fed group were similar to control. Severe atrophic changes in the testes and altered tissue architecture in lung and spleen as seen in the B12 deficient group were normalized in the Spirulina fed group. The study validates that Spirulina can improve the vitamin B12 status. PRACTICAL APPLICATIONS: The present study showed that the supplementation of Spirulina in the diet of vitamin B12 deficient rats leads to the normalization of vitamin B12 deficiency-induced circulatory and functional biomarkers along with biochemical and histological changes. Vegetarian sources for vitamin B12 are limited and the results presented here provide scientific validation for the use of Spirulina as a potential vegetarian source of bioavailable vitamin B12 .

Development of a carotenoid enriched probiotic yogurt from fresh biomass of Spirulina and its characterization.

Incorporation of Spirulina in milk as thermally dried powder has the disadvantages of non-uniform distribution with undesirable odor and flavor. Through homogenization (200 ± 10 bar), complete dispersion of fresh Spirulina biomass (7% w/w) in milk was achieved and thereafter a carotenoid enriched probiotic yogurt was developed. Confocal microscopy revealed porous Spirulina-milk protein matrix integrated with smaller fat globules in the yogurt. Spirulina led to a 29.56% increase in Lactobacillus acidophilus count, a 20% reduction in fermentation time and a total probiotic count of 1.2 × 107 CFU mL-1. The protein, total chlorophyll, total carotenoid and ß-carotene content (on dry w/w basis) were 3.58 ± 0.08 g 100 g-1, 0.407 ± 0.018 mg g-1, 0.235 ± 0.016 mg g-1 and 13.28 ± 0.08 µg g-1, respectively. During storage (18 days at 6-8 °C), the L. acidophilus count reached 8.83 ± 0.11 log CFU mL-1 with 103.03% increase in the viability by day three and the yogurt retained 71.5% carotenoids. The probiotc Spirulina yogurt was found to be acceptable to consumers as evaluated by affective consumer test.

Effect of different stripping techniques on pulpal temperature: in vitro study.

INTRODUCTION: Proximal stripping of enamel is a routine clinical procedure employed in orthodontics to create space or for balancing tooth size discrepancies. This procedure may result in heat transfer to the pulp, predisposing it to histopathological changes and necrosis of the pulp tissue. OBJECTIVE: To measure the temperature changes in the pulp chamber during different stripping procedures. METHODS: 80 proximal surfaces of 40 extracted human premolar teeth were stripped using four techniques: diamond burs in air-rotor handpiece with air-water spray; diamond burs in micromotor handpiece, with and without a coolant spray; and hand-held diamond strips. A J-type thermocouple connected to a digital thermometer was inserted into the pulp chamber for evaluation of temperature during the stripping procedure. RESULTS: An increase in the pulpal temperature was observed for all stripping method. Diamond burs in micromotor handpiece without coolant resulted in the higher increase in temperature (3.5oC), followed by hand-held diamond strips (2.8oC), diamond burs in air-rotor with air-water spray (1.9oC); and the smallest increase was seen with diamond burs in micromotor handpiece with coolant (1.65oC). None of the techniques resulted in temperature increase above the critical level of 5.5oC. CONCLUSION: Frictional heat produced with different stripping techniques results in increase in the pulpal temperature, therefore, caution is advised during this procedure. A coolant spray can limit the increase in temperature of the pulp.

Tuning the electronic properties of hexanuclear cobalt sulfide superatoms via ligand substitution.

Molecular clusters are attractive superatomic building blocks for creating materials with tailored properties due to their unique combination of atomic precision, tunability and functionality. The ligands passivating these superatomic clusters offer an exciting opportunity to control their electronic properties while preserving their closed shells and electron counts, which is not achievable in conventional atoms. Here we demonstrate this concept by measuring the anion photoelectron spectra of a series of hexanuclear cobalt sulfide superatomic clusters with different ratios of electron-donating and electron-withdrawing ligands, Co6S8(PEt3)6-x (CO) x (x = 0-3). We find that Co6S8(PEt3)6 has a low electron affinity (EA) of 1.1 eV, and that the successive replacement of PEt3 ligands with CO gradually shifts its electronic spectrum to lower energy and increases its EA to 1.8 eV. Density functional theory calculations reveal that the increase of EA results from a monotonic lowering of the cluster highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO). Our work provides unique insights into the electronic structure and tunability of superatomic building blocks.

Effect of different stripping techniques on pulpal temperature: in vitro study

ABSTRACT Introduction: Proximal stripping of enamel is a routine clinical procedure employed in orthodontics to create space or for balancing tooth size discrepancies. This procedure may result in heat transfer to the pulp, predisposing it to histopathological changes and necrosis of the pulp tissue. Objective: To measure the temperature changes in the pulp chamber during different stripping procedures. Methods: 80 proximal surfaces of 40 extracted human premolar teeth were stripped using four techniques: diamond burs in air-rotor handpiece with air-water spray; diamond burs in micromotor handpiece, with and without a coolant spray; and hand-held diamond strips. A J-type thermocouple connected to a digital thermometer was inserted into the pulp chamber for evaluation of temperature during the stripping procedure. Results: An increase in the pulpal temperature was observed for all stripping method. Diamond burs in micromotor handpiece without coolant resulted in the higher increase in temperature (3.5oC), followed by hand-held diamond strips (2.8oC), diamond burs in air-rotor with air-water spray (1.9oC); and the smallest increase was seen with diamond burs in micromotor handpiece with coolant (1.65oC). None of the techniques resulted in temperature increase above the critical level of 5.5oC. Conclusion: Frictional heat produced with different stripping techniques results in increase in the pulpal temperature, therefore, caution is advised during this procedure. A coolant spray can limit the increase in temperature of the pulp.

RESUMO Introdução: o desgaste proximal do esmalte é um procedimento clínico rotineiro utilizado na Ortodontia para se criar espaços ou equilibrar discrepâncias de tamanho dentário. Esse procedimento pode resultar em transferência de calor para a polpa, predispondo-a a mudanças histopatológicas e necrose do tecido pulpar. Objetivo: medir as mudanças de temperatura na câmara pulpar durante diferentes procedimentos de desgaste interproximal. Métodos: 80 superfícies proximais de 40 pré-molares humanos foram desgastadas utilizando-se quatro técnicas diferentes: brocas diamantadas em motor a ar (alta rotação) com spray de água e ar; brocas diamantadas em micromotor (baixa rotação) com e sem spray de resfriamento; e tiras diamantadas manuais. Um par termoelétrico do tipo J conectado a um termômetro digital foi inserido na câmara pulpar para avaliação da temperatura durante o desgaste proximal. Resultados: foi observado um aumento da temperatura da câmara pulpar em todos os métodos de desgaste proximal. As brocas diamantadas em micromotor sem resfriamento foram responsáveis pelo maior aumento da temperatura (3,5oC), seguidas pelas lixas diamantadas manuais (2,8oC) e brocas diamantadas em motor a ar (alta rotação) com spray de água e ar (1,9oC). O menor aumento foi observado com as brocas diamantadas em micromotor (baixa rotação) com resfriamento (1,65oC). Nenhuma das técnicas elevou a temperatura acima do nível crítico de 5,5oC. Conclusão: o aquecimento friccional produzido pelas diferentes técnicas de desgaste proximal levou ao aumento da temperatura da câmara pulpar; assim, cuidados devem ser tomados durante esse procedimento. O spray de água e ar pode limitar o aumento da temperatura da polpa.

Strong lowering of ionization energy of metallic clusters by organic ligands without changing shell filling.

Alkali atoms have unusually low ionization energies because their electronic structures have an excess electron beyond that of a filled electronic shell. Quantum states in metallic clusters are grouped into shells similar to those in atoms, and clusters with an excess electron beyond a closed electronic may also exhibit alkali character. This approach based on shell-filling is the way alkali species are formed as explained by the periodic table. We demonstrate that the ionization energy of metallic clusters with both filled and unfilled electronic shells can be substantially lowered by attaching ligands. The ligands form charge transfer complexes where the electronic spectrum is lifted via crystal field like effect. We demonstrate that the effect works for the weakly bound ligand, N-ethyl-2-pyrrolidone (EP = C6H11NO), and that the effect leads to a dramatic lowering of the ionization energy independent of the shell occupancy of the cluster.

Strong Effect of Organic Ligands on the Electronic Structure of Metal-Chalcogenide Clusters.

It is shown that multiple ionization energies of metal-chalcogenide clusters can be substantially reduced by adding ligands that form charge transfer complexes. We demonstrate this intriguing phenomenon by considering metal-chalcogenide clusters including cases where a cluster has a filled electronic shell with a large gap between the occupied and unoccupied states reminiscent of stable species. The studies include a Co6Se8 core ligated with tri-ethylphosphine (PEt3) ligands forming a stable Co6Se8(PEt3)6 species. All of the ligated clusters have a first ionization energy in the range for alkali atoms and multiple ionization energies that are considerably lower than those for the non-ligated clusters. The change in electronic behavior upon ligation can be associated with a shift in the electronic spectrum via a crystal field like effect due to attaching ligands that form charge transfer complexes. We also show that metal-chalcogenide species can be programmed by proper ligand replacement to promote dimerization by first forming the Co6Se8(PEt3) n(CO)6- n ( n = 0-6) clusters where the CO ligands could be replaced by diisocyanide (CNC6H4NC) ligands. The diisocyanide ligand acts as a rigid linker between the metallic cores, enabling the formation of a Co6Se8(PEt3)5(CNC6H4NC)Co6Se8(PEt3)5 superatomic molecule (SM), and we examine the electronic and magnetic properties of the recently synthesized SM via studies on an analogous SM with smaller ligands.