1-Cyclohepta-2,4,6-trienyl-selanes--a 77Se NMR study: indirect nuclear 77Se--13C spin-spin coupling constants and application of density functional theory (DFT) calculations

1-Cyclohepta-2,4,6-trienyl-selanes Se(C(7)H(7))(2) (2c), R--Se--C(7)H(7) with R = Bu, (t)Bu, Ph, 4-F--C(6)H(4) (12a,b,c,d) were prepared by the reaction of the corresponding silanes, Si(SeMe(3))(2) and R--Se--SiMe(3), respectively, with tropylium bromide C(7)H(7)Br. In spite of the low stability of the selanes even in dilute solutions and at low temperature, they could be characterised by their (1)H, (13)C and (77)Se NMR parameters. Coupling constants (1)J((77)Se,(13)C) were measured and calculated by DFT methods at the B3LYP/6-311+G(d,p) level of theory. The comparison of experimental and calculated coupling constants (1)J((77)Se,(13)C) included numerous selenium carbon compounds with largely different Se--C bonds, revealing a satisfactory agreement. Both the spin-dipole (SD) and the paramagnetic spin-orbital (PSO) terms contributed significantly to the spin-spin coupling interaction, in addition to the Fermi contact (FC) term.     

Polymeric organometallic architectures of novel P-Se anions

The characterisation of a series of compounds obtained from Woollins' reagent (W.R.) offers a novel approach to organometallic coordination polymers. The syntheses were achieved by nucleophilic ring-opening reactions of W.R. with metal salts and crystallisation using solvent-diffusion techniques. One-dimensional coordination polymers are formed as a result, and we demonstrate that the dimensionality of the polymers can be influenced by using hydrated metal salts or by the construction of heterometallic arrangements.     

通透结构泡沫硒化铜原位构筑及烟气脱汞研究

燃煤烟气汞的大量排放对公众健康和生态系统造成了严重威胁,开发新型高效脱汞技术和材料对汞污染防治具有重要意义。本文采用原位硒化方法制备了泡沫硒化铜(Cu-hs),与采用水热法制备的泡沫硒化铜(Cu-hd-1和Cu-hd-12)相比,Cu-hs具有更优的单质汞(Hg⁰)吸附性能。Cu-hs具有良好的抗H₂O和SO₂干扰能力,O₂对Cu-hs吸附Hg⁰有一定的促进作用,而HCl的存在对Hg⁰吸附没有明显影响。Cu-hs表面的汞饱和吸附量为3743 g/m³(约为15 mg/g),显著高于目前文献中报道的活性炭的饱和吸附量,具有很好的燃煤烟气脱汞应用潜力。     

Kinetic modelling of ultrasound-assisted extraction of phenolics from cereal brans

Cereal brans are by‐products of the milling of cereal grains, which are mainly used as low value ingredients in animal feed. Wheat and oat bran is a rich source of bioactives and phytochemicals, especially phenolic compounds. Within this study, the application of ultrasound (US) technology to assist the extraction of phenolics from oat and wheat bran was investigated (20–45 kHz). Peleg’s mathematical model was used to study the kinetics of ultrasound-assisted extraction (UAE) and subsequent stirring of total phenolic compounds (TPC). The surface morphology of cereal brans after extraction was studied using SEM analysis. The excellent agreement was determined between the values of TPC calculated from Peleg’s mathematical model and actual experimental results. The constant that represents a time required for the initial phenolic concentration to be extracted to one-half of its initial value has been introduced (K_1/2). It was shown that the TPC extraction kinetics was dependent only on K_1/2 enabling fast kinetics fitting and comparison between extraction rates. Moreover, different values of K_1/2 constant could indicate the differences in brans composition and consequently different influence of US pretreatment on these samples.     

Total syntheses of bupleurynol and its analog

An efficient route to the natural products bupleurynol and its analog (RB-2), isolated from Bupleuri Radix, was established based on versatile intermediate (15). In this synthetic route, Sonogashira and Cadiot-Chodkiewicz coupling as well as Julia-Kocienski olefination are utilized as key steps. The highly efficient synthetic route provides opportunities to explore the biological behavior of bupleurynol and RB-2.     

人工神经网络催化动力学光度法同时测定硒和铁

在酸性介质中,硒(Ⅳ)和铁(Ⅲ)同时催化H_2O_2氧化二甲基黄褪色反应.研究发现:两者对H_2O_2氧化二甲基黄褪色反应的催化作用不具有加和性.根据这一现象,结合人工神经网络,建立了一种新的不经分离可同时测定硒(Ⅳ)和铁(Ⅲ)混合物中硒(Ⅳ)和铁(Ⅲ)各自含量的分析方法.方法应用于合成样品及烟草样品中硒(Ⅳ)和铁(Ⅲ)的测定,结果满意.     

Behavior of the Cricopharyngeal Segment During Esophageal Phonation in Laryngectomized Patients

BACKGROUND: After total laryngectomy, the interruption of the upper digestive tube and the section of the cricopharyngeal segment alter the high-pressure zone of the pharyngoesophageal transition, which will not only start to have a digestive function, but also be stimulated to take on the production of voice and speech. The pressure observed in the cricopharyngeal segment seems to act as a critical factor for the development of esophageal sound production, and manometry is the procedure capable of quantifying the pressure observed in this region. OBJECTIVE: The objective of the current study was to assess the upper esophageal sphincter pressure in laryngectomized patients who are either successful or unsuccessful esophageal speakers, both at rest and during esophageal phonation, using manometry. METHODS: Twenty laryngectomized persons aged 32 to 83 years (mean, 44.2 years) were submitted to evaluation by a speech pathologist and divided into two groups, ie, successful esophageal speakers (N=12) and unsuccessful esophageal speakers (N=8), according to a scale validated by Wepman et al (1953). The upper esophageal sphincter (UES) pressure was assessed by manometry both at rest and during the following voice emissions in Portuguese: the vowel "a," the monosyllable "pa," and the sentence "papai papou pipoca." The amplitude, the duration of the pressure wave, and the area under the curve were measured. RESULTS: At rest, the mean UES pressure was 11.83 mm Hg for successful esophageal speakers and 9.92 mm Hg for unsuccessful esophageal speakers, with no significant difference between groups; the mean for the two groups as a whole was 11.06 mm Hg. During the voice and speech sequence tests, no significant difference was observed when the emissions in Portuguese of "a," "pa," and the sentence were analyzed separately. CONCLUSION: As the pressure observed at rest did not differ between the successful esophageal speakers and the unsuccessful esophageal speakers, and the amplitude, the duration of the pressure wave, and the area under the amplitude x duration curve were also equal for both groups, we conclude that the cricopharyngeal segment pressure is not a preponderant factor for the acquisition of esophageal voice and speech.     

Noninvasive quantification of fluid mechanical energy losses in the total cavopulmonary connection with magnetic resonance phase velocity mapping

A major determinant of the success of surgical vascular modifications, such as the total cavopulmonary connection (TCPC), is the energetic efficiency that is assessed by calculating the mechanical energy loss of blood flow through the new connection. Currently, however, to determine the energy loss, invasive pressure measurements are necessary. Therefore, this study evaluated the feasibility of the viscous dissipation (VD) method, which has the potential to provide the energy loss without the need for invasive pressure measurements. Two experimental phantoms, a U-shaped tube and a glass TCPC, were scanned in a magnetic resonance (MR) imaging scanner and the images were used to construct computational models of both geometries. MR phase velocity mapping (PVM) acquisitions of all three spatial components of the fluid velocity were made in both phantoms and the VD was calculated. VD results from MR PVM experiments were compared with VD results from computational fluid dynamics (CFD) simulations on the image-based computational models. The results showed an overall agreement between MR PVM and CFD. There was a similar ascending tendency in the VD values as the image spatial resolution increased. The most accurate computations of the energy loss were achieved for a CFD grid density that was too high for MR to achieve under current MR system capabilities (in-plane pixel size of less than 0.4 mm). Nevertheless, the agreement between the MR PVM and the CFD VD results under the same resolution settings suggests that the VD method implemented with a clinical imaging modality such as MR has good potential to quantify the energy loss in vascular geometries such as the TCPC.