Effect of Bulk Composition on the Heterogeneous Oxidation of Semi-Solid Atmospheric Aerosols

Abstract: The OH-initiated heterogeneous oxidation of semi-solid saccharide particles with varying bulk compositions was investigated in an atmospheric pressure flow tube at 30% relative humidity. Reactive uptake coefficients were determined from the rate loss of the saccharide reactants measured by mass spectrometry at different monosaccharide (methyl-β-d-glucopyranoside, C7H14O6) and disaccharide (lactose, C12H22O11) molar ratios. The reactive uptake for the monosaccharide was found to decrease from 0.53 ± 0.10 to 0.05 ± 0.06 as the mono-to-disaccharide molar ratio changed from 8:1 to 1:1. A reaction–diffusion model was developed in order to determine the effect of chemical composition on the reactive uptake. The observed decays can be reproduced using a Vignes relationship to predict the composition dependence of the reactant diffusion coefficients. The experimental data and model results suggest that the addition of the disaccharide significantly increases the particle viscosity leading to slower mass transport phenomena from the bulk to the particle surface and to a decreased reactivity. These findings illustrate the impact of bulk composition on reactant bulk diffusivity which determines the rate-limiting step during the chemical transformation of semi-solid particles in the atmosphere

A rare case of Nabothian cyst presenting as mass per vagina

Nabothian cysts are benign non neoplastic disorder rarely of any clinical significance usually appear as bumps on the surface of the cervix which may be single or in groups and they appear as a sequalae to chronic cervicitis, are asymptomatic unless they are sizeable presenting with rare and varied symptoms. Generally, Nabothian cysts do not require any therapy. The therapy is recommended when a patient becomes symptomatic with pain or when the lesion character is not clear and malignancy cannot be ruled out. Here we reported a case of 23-year young unmarried girl nulligravida with complaints of mass per vagina. On local examination an irregular polypoidal mass was seen protruding outside the introitus measuring about 4×4 cm soft to cystic in consistency. Ultrasound revealed a well-defined anechoic cyst of 3.6×5.7 cm noted in the right ovary with no evidence of internal septation/solid component and wall calcification suggestive of right ovarian simple cyst with left ovary and uterus being normal. Surgical management was planned. Diagnostic laparoscopy was performed which revealed right ovarian simple cyst of 6×4 cm which was punctured using cautery and drained. Following this vaginal exploration revealed a polypoidal structure of 5×4 cm cystic consistency seen arising from right upper anterolateral lip of cervix. Polyp was resected with cautery and haemostasis achieved. Post operative period was uneventful. Such rare presentations do pose a diagnostic dilemma and hence it should be kept in mind to ensure adequate treatment

The C(3P) + NH3 reaction in interstellar chemistry: II. Low temperature rate constants and modeling of NH, NH2 and NH3 abundances in dense interstellar clouds

A continuous supersonic flow reactor has been used to measure rate constants for the C + NH3 reaction over the temperature range 50 to 296 K. C atoms were created by the pulsed laser photolysis of CBr4. The kinetics of the title reaction were followed directly by vacuum ultra-violet laser induced fluorescence (VUV LIF) of C loss and through H formation. The experiments show unambiguously that the reaction is rapid at 296 K, becoming faster at lower temperatures, reaching a value of 1.8 10-10 cm3 molecule-1 s-1 at 50 K. As this reaction is not currently included in astrochemical networks, its influence on interstellar nitrogen hydride abundances is tested through a dense cloud model including gas-grain interactions. In particular, the effect of the ortho-to-para ratio of H2 which plays a crucial role in interstellar NH3 synthesis is examined

A bonding evolution theory study of the reaction between methylidyne radical, CH(X2Π), and cyclopentadiene, C5H6

In the present work, bonding evolution theory (BET) is applied to gain insight about the complex reaction between methylidyne radical, CH (X2 Π) and cyclopentadiene, C5H6. The novelty of this work is that all reaction pathways take place in the doublet electronic state and an unpaired electron is always present. Therefore, taking the aforementioned reaction as explicative example, we have shown how to apply the BET tool to these kinds of open-shell systems, by splitting the wavefunctions into the corresponding alpha and beta parts. As an added value, we have included a point-by-point description of the algorithm we use to make it available for the readers. Hence, a complete analysis of bond breaking/forming and charge redistribution along the multi-channels connecting reactants to products via the transition states and intermediates is presented. We show how the BET brings about the representation of the electronic flow in complex molecular rearrangements like the one herein studied, yielding a transparent rationalization based on the electron density redistribution. The present study allows us to conclude that along the different processes giving rise to the benzene product, the breaking of a C C sigma bond initiates the electronic rearrangement in two cases, but not in the third one. The last step in these processes can be described as an initial weakening of the C H bond with a quasi-hydride formation and a final retro-transfer of electrons from the quasi-hydride to the C H bond. On the other hand, in the way to the fulvene product, the breaking of the C C sigma bond takes place after previous electronic redistribution. Neither the last step of the fulvene formation process nor the interesting H transfer described in the second one, can be explaiFunding for open access charge: CRUE-Universitat Jaume

Health Care Seeking and Risk Behaviors among High School Students in the Context of a School-Based Health Center

Background. To address adolescent health needs in urban Wyandotte County, Kansas, a school-based health center (SBHC) was opened in March 2012. Students were surveyed to inform SBHC operations. Methods. All Wyandotte High School students were invited to complete an online survey in class in May 2012. Questions on demographics, health care seeking behaviors, behavioral risk factors, and missed school days were included. Results. Of 1,240 eligible students, 398 responded (32.3%). Nearly half (45.8%) reported that the emergency room or hospital was the location where they usually would seek health care. Females were more likely than males to report less access to mental health counseling (15.1% vs 10.8%, p = 0.01) or reproductive health care (7.7% vs 5.7%, p = 0.03) when needed and were more likely to miss school due to a health problem (54.0% vs 37.9% missed ≥ 1 day in past 4 weeks, p = 0.006). Males were more likely to report having had sex (59.2% vs 46.9%, p = 0.02) while females were more likely to report never using a condom when having sex (30.6% vs 18.3%, p = 0.001). Almost two-thirds (61.9%) of respondents were aware of the SBHC; 18.7% had used the SBHC. Conclusions. Students do not have adequate access to primary care, including sexual and mental health care. Using these data, the SBHC can be better adapted to meet student needs

ЭПИСТЕМОЛОГИЯ ИНТЕЛЛЕКТУАЛЬНЫХ СИСТЕМ НАУЧНОГО ПОИСКА

The paper studies problems pertaining to development of intellectual scientific search systems from the point of view of epistemology as a science on knowledge, its functioning and development. The most important epistemological postulates are determined in the paper and these postulates serve as a basis for an analysis of intellectual technologies of creative search and knowledge formation. Using a systematic approach to study of intellectual technologies of the innovation search the paper considers division of knowledge system in its components – properties of an object to be investigated (separate knowledge clusters). The mentioned approach and adopted biophysical analogies in the investigation of the intellectual technology on knowledge formation have made it possible to identify one of the key epistemology problems in respect of intellectual systems that is an initial uncertainty of scientific search purpose. In this connection a structure of value-orientated knowledge search in the intellectual medium is determined in the paper. The paper also analyzes process pertaining to transformation of value orientation of scientific search into its purposeful development. A role of intellectual systems of scientific search concerning knowledge synthesis of various cognate practices is considered in the paper. The paper proposes a variant pertaining to creation of generalized information image of the studied phenomenon in the intellectual medium on the basis of frame models of knowledge systems from various cognate practices.Рассмотрены проблемы создания интеллектуальных систем научного поиска с точки зрения эпистемологии как науки о знаниях, их функционировании и развитии. Определены важнейшие эпистемологические начала, на которых базируется анализ интеллектных технологий творческого поиска и формирования знаний. На основе системного подхода к изучению интеллектных технологий инновационного поиска рассмотрено членение системы знаний на ее составляющие – свойства объекта исследования (отдельные кластеры знаний). Указанный подход и принятые биофизические аналогии в исследовании интеллектной технологии формирования знаний позволили выделить одну из ключевых проблем эпистемологии интеллектуальных систем – начальную неопределенность цели научного поиска. В связи с этим определена структура ценностноориентированного поиска знаний в интеллектуальной среде и проанализирован процесс преобразования ценностной ориентации научного поиска в его целенаправленное развитие. Рассмотрена роль интеллектуальных систем научного поиска в вопросах синтеза знаний различных практик когнитологии. Предложен вариант создания обобщенного информационного образа изучаемого явления в интеллектуальной среде на основе фреймовых моделей систем знания из различных когнитивных практик

Flow tube studies of the C(3P) reactions with ethylene and propylene

International audienceProduct detection studies of C(3P) atom reactions with ethylene, C2H4(X1Ag) and propylene, C3H6(X1A′) are carried out in a flow tube reactor at 332 K and 4 Torr (553.3 Pa) under multiple collision conditions. Ground state carbon atoms are generated by 193 nm laser photolysis of carbon suboxide, C3O2 in a buffer of helium. Thermalized reaction products are detected using tunable VUV photoionization and time of flight mass spectrometry. For C(3P) + ethylene, propargyl (C3H3) is detected as the only molecular product in agreement with previous studies on this reaction. The temporal profiles of the detected ions are used to discriminate C(3P) reaction products from side reaction products. For C(3P) + propylene, two reaction channels are identified through the detection of methyl (CH3) and propargyl (C3H3) radicals for the first channel and C4H5 for the second one. Franck–Condon Factor simulations are employed to infer the C4H5-isomer distribution. The measured 1:4 ratio for the i-C4H5 isomer relative to the methylpropargyl isomers is similar to the C4H5 isomer distribution observed in low-pressure flames and differs from crossed molecular beams data. The accuracy of these isomer distributions is discussed in view of large uncertainties on the photoionization spectra of the pure C4H5 isomer

From Stroke to Dementia: a Comprehensive Review Exposing Tight Interactions Between Stroke and Amyloid-β Formation

Stroke and Alzheimer’s disease (AD) are cerebral pathologies with high socioeconomic impact that can occur together and mutually interact. Vascular factors predisposing to cerebrovascular disease have also been specifically associated with development of AD, and acute stroke is known to increase the risk to develop dementia. Despite the apparent association, it remains unknown how acute cerebrovascular disease and development of AD are precisely linked and act on each other. It has been suggested that this interaction is strongly related to vascular deposition of amyloid-β (Aβ), i.e., cerebral amyloid angiopathy (CAA). Furthermore, the blood–brain barrier (BBB), perivascular space, and the glymphatic system, the latter proposedly responsible for the drainage of solutes from the brain parenchyma, may represent key pathophysiological pathways linking stroke, Aβ deposition, and dementia. In this review, we propose a hypothetic connection between CAA, stroke, perivascular space integrity, and dementia. Based on relevant pre-clinical research and a few clinical case reports, we speculate that impaired perivascular space integrity, inflammation, hypoxia, and BBB breakdown after stroke can lead to accelerated deposition of Aβ within brain parenchyma and cerebral vessel walls or exacerbation of CAA. The deposition of Aβ in the parenchyma would then be the initiating event leading to synaptic dysfunction, inducing cognitive decline and dementia. Maintaining the clearance of Aβ after stroke could offer a new therapeutic approach to prevent post-stroke cognitive impairment and development into dementia

Pharmacokinetic and pharmacodynamic study of intranasal and intravenous dexmedetomidine

Background: Intranasal dexmedetomidine produces safe, effective sedation in children and adults. It may be administered by drops from a syringe or by nasal mucosal atomization (MAD NasalTM). / Methods: This prospective, three-period, crossover, double-blind study compared the pharmacokinetic (PK) and pharmacodynamic (PD) profile of i.v. administration with these two different modes of administration. In each session each subject received 1 μg kg−1 dexmedetomidine, either i.v., intranasal with the atomizer or intranasal by drops. Dexmedetomidine plasma concentration and Ramsay sedation score were used for PK/PD modelling by NONMEM. / Results: The i.v. route had a significantly faster onset (15 min, 95% CI 15–20 min) compared to intranasal routes by atomizer (47.5 min, 95% CI 25–135 min), and by drops (60 min, 95%CI 30–75 min), (P<0.001). There was no significant difference in sedation duration across the three treatment groups (P=0.88) nor in the median onset time between the two modes of intranasal administration (P=0.94). A 2-compartment disposition model, with transit intranasal absorption and clearance driven by cardiac output using the well-stirred liver model, was the final PK model. Intranasal bioavailability was estimated to be 40.6% (95% CI 34.7–54.4%) and 40.7% (95% CI 36.5–53.2%) for atomization and drops respectively. Sedation score was modelled via a sigmoidal Emax model driven by an effect compartment. The effect compartment had an equilibration half time 3.3 (95% CI 1.8–4.7) min−1, and the EC50 was estimated to be 903 (95% CI 450–2344) pg ml−1. / Conclusions: There is no difference in bioavailability with atomization or nasal drops. A similar degree of sedation can be achieved by either method. / Clinical trial registration: HKUCTR-1617