Isomerization of Linear C3H+3 in its reaction with acetylene, and collisional stabilization of the [C5H+5]* collision complex in a quadrupole ion trap mass spectrometer

AbstractThe isomerization of linear C3H+3 in its reaction with acetylene to cyclic C3H+3 was studied with a quadrupole ion trap mass spectrometer. The reaction of linear C3H+3 with 13C2H2 shows that isomerization takes place via a [C5H+5]* activated complex that is unstable relative to disproportionation back into the cyclic and linear forms of C3H+3 and acetylene. The formation of carbon-13 labeled cyclic and linear C3H+3 indicates that isomerization involves skeletal exchange. Collisional stabilization of the [C5H+5]* collision complex was achieved at a helium pressure of approximation 1 mtorr

Mass spectrometer apparatus for analyzing multiple fluid samples concurrently

A mass spectrometer utilizing an inlet nozzle having multiple atmospheric pressure inlets to provide multiple streams of different fluid samples such that their chemical contents can be analyzed simultaneously within a single mass spectrometer with limited or no interaction between the individual streams of sample. This capability is made possible by positioning the nozzle within a nozzle housing wherein the nozzle defines a plurality of orifices extending therethrough from the atmospheric pressure environment of the orifice inlets to the reduced air pressure environment of the nozzle outlets without allowing any mixing between the samples as they pass through the nozzle. Samples are provided to the nozzle by an electrospray ionization needle which simultaneously ionizes the fluid and supplies it to one individual nozzle orifice. Multiple electrospray ionization spray means are provided with one for each fluid sample to prevent mixing therebetween and to facilitate simultaneous analysis of different fluid samples within a mass spectrometer particularly as used within a time-of-flight mass spectrometer. The nozzle allows the samples to pass into a quadrupole ion guide which carries the sample into the detector apparatus for analysis thereof.Board of Regents, University of Texas Syste

Alcohol-assisted versus Mechanical Epithelium Removal in Photorefractive Keratectomy

Purpose: To compare the outcomes and complications of alcohol-assisted versus mechanical corneal epithelial debridement for photorefractive keratectomy (PRK). Methods: This randomized controlled trial included 1,250 eyes of 625 patients undergoing PRK for correction of myopia and myopic astigmatism. Each patient was randomly assigned to alcohol-assisted or mechanical epithelial removal. Results: A total of 658 eyes underwent alcohol-assisted epithelial removal while the epithelium was removed mechanically in 592 eyes. Mean spherical equivalent was ‑4.37}2.3 D in the alcohol group and ‑3.8}1.3 D in the mechanical group (P = 0.78). There was no significant difference in postoperative pain between the study groups (P = 0.22). Uncorrected visual acuity ≥ 20/20 and ≥ 20/40 was achieved in 90.9% versus 93.4% (P = 0.08), and 98.9% versus 99.5% (P = 0.36) of eyes in the alcohol and mechanical groups, respectively. Final refractive error within 1D of emmetropia was achieved in 90% versus 92.2% of eyes in the alcohol and mechanical groups, respectively (P = 0.23). Alcohol-assisted debridement required less time than mechanical debridement (96±18 vs. 118±26 seconds, P=0.035). There was no significant difference between the two groups in terms of early and late postoperative complications. Conclusion: Alcohol-assisted and mechanical epithelium removal are comparable in terms of efficacy and side effects. The method of epithelial debridement in PRK may be left to the surgeon′s choice

Validation of effective factors on new teachers' organizational trauma management with artificial neural network approach

Organizational trauma management is a neglected public health crisis, while it seems to be a very important issue that should be properly addressed. The present study was conducted with the aim of validating the effective factors on the organizational trauma management of new teachers with the approach of artificial neural network (ANN). The present research method was quantitative in terms of strategy and descriptive-correlation in terms of technique. The statistical population of the new research was teachers of Gilan, Alborz and Tehran provinces with a population of 15,000 people. A sample of 375 people was selected from this population by multi-stage cluster sampling method. A researcher-made questionnaire (1401) was used to collect data. In order to analyze the data, artificial neural network with multilayer perceptron method (MLP) was used using SPSS25 software. The findings showed that organizational trauma management has an input layer with 21 nodes and a hidden layer with 9 nodes, which includes psychological empowerment with the greatest effect and psychological safety with the least importance factor in organizational trauma management. According to the studies, psychological crises in organizations have become a common experience for managers and employees around the world. Some of these crises show signs of traumatic experience. If it is not managed properly, it seems that the experience of collective harm appears in the form of many organizational factors that lead to dysfunctional behavior in the organization

A Review of Manufacturing Process of Polyethylene Pipe and Connectors for Applying in High-Pressure Natural Gas Pipelines

In this article various pipes used for transporting of gas are introduced and pros and cons of each one are elucidated. The pipes are categorized in three different subgroups including metallic, polymeric and metallic-wire reinforced polymeric pipes. Metallic-wire reinforced polymeric pipes are nominated as the best option for usage in high pressure pipelines transporting natural gas. As a result, some information about major manufacturers of this kind of polymeric pipes, raw material, production process and metallic-wire orientation are presented. Finally, from economical point of view, some calculations are done to estimate required amount of polymer and metallic-wire to manufacture such pipes. It is also possible to compare their manufacturing cost with usual metallic and polymeric pipes

Sleep patterns and habits in high school students in Iran

<p>Abstract</p> <p>Background</p> <p>Sleep patterns and habits in high school students in Iran have not been well studied to date. This paper aims to re-address this balance and analyse sleep patterns and habits in Iranian children of high school age.</p> <p>Methods</p> <p>The subjects were 1,420 high school students randomly selected by stratified cluster sampling. This was a self-report study using a questionnaire which included items about usual sleep/wake behaviours over the previous month, such as sleep schedule, falling asleep in class, difficulty falling asleep, tiredness or sleepiness during the day, difficulty getting up in the morning, nightmares, and taking sleeping pills.</p> <p>Results</p> <p>The mean duration of night sleep was 7.7 h, with no difference between girls, boys, and school year (grade). The mean time of waking in the morning was not different between genders. About 9.9% of the girls and 4.6% of the boys perceived their quality of sleep as being bad, and 58% of them reported sleepiness during the day. About 4.2% of the subjects had used medication to enhance sleep. The time of going to bed was associated with grade level and gender. Sleep latency was not associated with gender and grade leve, l and 1.4% experienced bruxism more than four times a week.</p> <p>Conclusion</p> <p>Our results are in contrast with that of previous studies that concluded sleep duration is shorter in Asia than in Europe, that boys woke-up significantly later than girls, and that the frequency of sleep latency category was associated with gender and grade level. The magnitude of the daytime sleepiness, daytime sleepiness during classes, sleep latency, and incidences of waking up at night represent major public health concerns for Iran.</p

Sheathless interface for capillary electrophoresis/electrospray ionization-mass spectrometry using an in-capillary electrode

A simple and rugged sheathless interface for capillary electrophoresis/electrospray ionization-mass spectrometry (CE/ESI-MS) was designed using common laboratory tools and chemicals. The interface uses a small platinum (Pt) wire which is inserted into the CE capillary through a small hole near the terminus. The position of the wire inside the CE capillary and within the buffer solution is analogous to standard CE separation operations where the terminus of the CE capillary is placed inside a buffer reservoir along with a grounded platinum electrode. By combining the use of the in-capillary electrode interface with sharpening of the fused silica tip of the CE capillary outlet, a stable electrospray current was maintained for an extended period of time. The design was successfully applied to CE/ESI-MS separations and analysis of mixtures of peptides and proteins. A detection limit of approximately 4 femtomole (S/N=3) was achieved for detection of myoglobin utilizing a 75 μm-i.d. aminopropylsilane treated CE column and using a wide scan range of 550-1350 Da. The advantages of this new design include: (1) a stable CE and ESI current, (2) durability, (3) a reduced risk of sparking between the capillary tip and the inlet of the mass spectrometer, (4) lack of any dead volume, and (5) facile fabrication with common tools and chemicals.Board of Regents, University of Texas Syste

Interfacing low-flow separation techniques

A capillary column, and method for forming a capillary column, in which the capillary column comprises at least one porous segment at a terminus of the capillary column, wherein the at least one porous segment is formed by exposing the segment to one or more of a solution of acid, base, and a mechanical tool.Board of Regents, University of Texas Syste