Half-value Time Research Articles

Feature statistics and analysis of transient overvoltage waveform measured from 220 kV substation

The electromagnetic transient overvoltage in the substation is an important factor that affects the life of insulation equipment. For evaluate the economy and reliability of the insulation design of substation equipment, it is necessary to study and analyze the actual measured overvoltage waveforms in the substation. In this paper, firstly, the 3018 pieces of overvoltage data monitored in the 220 kV substation from 2018 to 2019 are preprocessed to obtain the required overvoltage waveform. Next, by analyzing and classifying the overvoltage data, four typical overvoltage waveforms suffered by the insulation equipment in the substation are extracted. Combined with the IEC60060 standard, the time parameters of the overvoltage waveform are selected and defined: wave-front time (Tf), half-value time (Thalf), main oscillation frequency (f), and attenuation constant (α). Further, statistical analysis is performed on the parameters of each waveform. The distribution law, distribution characteristics and distribution range of the parameters are obtained. Finally, the parameters of four typical overvoltage waveforms are summarized and compared, the cumulative distribution functions are obtained. This results can guide and optimize the insulation design of the insulation equipment in the substation, reduce design errors. It provide data support for the economy and reliability of insulation design.

Endovenous glue ablation for chronic venous insufficiency: A comprehensive 5-year assessment of clinical and hemodynamic outcomes.

Chronic venous insufficiency is mainly caused by reflux, obstruction, or both. Endovenous glue ablation has become one of the widely used methods for treating reflux in recent years. Duplex ultrasonography is the most commonly used method for diagnosing and evaluating treatment. However, there is important information that plethysmographic venous hemodynamics provides, which Duplex USG cannot provide. This retrospective study aimed to evaluate the 5-year clinical, anatomical, and hemodynamic results of endovenous glue ablation in the treatment of chronic venous insufficience, accompanied by the data from the plethysmographic study. Between January 2018 and August 2018, 133 patients with symptomatic CEAP 2-6 varicose veins with reflux of the great saphenous vein lasting longer than 0.5 seconds and a diameter of 5.5mm in the standing great saphenous vein underwent EVGA. CEAP, VCSS, CIVIQ 20, Doppler USG, GSV diameters and insufficiency times, and hemodynamically Venous Refilling Time and Venous Half-Value Time measurements were performed before the procedure. In the same way, measurements were made at the 1st, 3rd, 6th, 12th, 24th, and 60th months of the patients who were called and came to the postoperative follow-up. Procedural success was 100%, and complete occlusion was observed %93 after treatment, at the 60month. The improvement in VCSS (from 4.4 ± 1.3 to 1.7 ± 0.9), CIVIQ20 (from 8.5 ± 3.1 to 4.7 ± 2.0), VRT (from 20.3 ± 5.0 to 131.1 ± 4.0), and TH (from 2.8 ± 0.3 to 2.4 ± 0.2) was significant (p < .001 was for all). Endovenous glue ablation is a preferred method for the treatment of great saphenous vein insufficiency due to its ease of use and the comfort it provides to patients, as well as its effectiveness and safety. In particular, it can be considered an effective method for improving venous hemodynamics and relieving associated symptoms.

CO2 gas hydrate as an innovative leavening agent for baked goods

In the presented research, the use and technical realization of CO2 gas hydrate (GH) as a novel baking agent is investigated. GH are ice-like structures where one mole of hydrate typically consists of about 85% water and 15% gas. Hydrates were formed in a lab-scale 1.1 L stirred tank reactor at 1-2 °C and 3.5 MPa, and transferred into a temperature-controlled, gas-tight measuring cell. The leavening effect of gas hydrates was assessed by measuring the CO2 release rates. Storage stability at -20 to 0 °C and stability above 0 °C were investigated experimentally and a coupled thermodynamic and kinetic decay model implemented. At -10 °C, gas release was highest in the first minutes and stopped completely after 5 days. After 21 days storage at -10 °C, the GH still contained 20 % of the initial gas content. Above 0 °C, dissociation rates were highly temperature dependent, and half value times ranged from 30 min (3 °C) to 4 min (20 - 30 °C). Above 10 °C, ambient temperature had only a minor effect on the dissociation rates. Results from the kinetic decay model, applied for a 21 mm particle, showed similar dissociation behavior as a particle from experiments. Applying the model for a 3 mm particle, showed full dissociation after approximately 15 min. Stability and baking tests showed that CO2 hydrate is in principle suitable as a leavening agent. However, GH production still needs to be optimized and recipes for GH application require further development.

Diagnosing Sport-Related Flow Limitations in the Iliac Arteries Using Near-Infrared Spectroscopy.

Background: A flow limitation in the iliac arteries (FLIA) in endurance athletes is notoriously difficult to diagnose with the currently available diagnostic tools. At present, a commonly used diagnostic measure is a decrease in ankle brachial index with flex hips (ABIFlexed) following a maximal effort exercise test. Near-infrared spectroscopy (NIRS) is a non-invasive technique that measures skeletal muscle oxygenation as reflected by the balance of O2 delivery from microvascular blood flow and O2 uptake by metabolic activity. Therefore, NIRS potentially serves as a novel technique for diagnosing FLIA. The purpose of this study is to compare the diagnostic accuracy of NIRS-derived absolute, amplitude, and kinetic variables in legs during and after a maximal exercise test with ABIFlexed. Methods: ABIFlexed and NIRS were studied in 33 healthy subjects and 201 patients with FLIA diagnosed with echo-Doppler. Results: After maximal exercise, NIRS kinetic variables, such as the half value time and mean response time, resulted in a range of 0.921 to 0.939 AUC for the diagnosis of FLIA when combined with ABIFlexed. Conversely, ABIFlexed measurements alone conferred significantly worse test characteristics (AUC 0.717, p < 0.001). Conclusions: NIRS may serve as a diagnostic adjunct in patients with possible FLIA.

K2CO3- and K2CO3/porous SiO2-doped steam activated extruded carbons based on multi-component biochar composite: Preparation, characterization and kinetic gasification behavior

In this work, the preparation and characterization of new steam-activated K2CO3/porous SiO2-doped extruded activated carbons based on multi-component biochar composite with different gasification levels are described and compared with K2CO3-doped extruded activated carbons. The steam activation was performed in a rotary kiln quartz tube reactor in batch mode (Froude number: 1.59 × 10–3, volumetric filling degree < 6%) at an activation temperature of 880 °C. The prepared activated carbons were characterized by chemical analyses, X-ray fluorescence spectroscopy (XRF), BET-surface area and porosity measurements. The gasification of the K2CO3-doped carbons follows a zero-order kinetic with a reaction rate constant of k0 = 5.25 × 10–3 min–1 and a half-value time of τ0.5 = 95.2 min indicating that the K2CO3 catalyst maintains the catalytic activity during steam activation up to a carbon conversion of XC = 68%. The co-gasification of the K2CO3/porous SiO2-doped carbons can preferably be described by applying the shrinking unreacted grain model (SUGM) for spherical particles. A reaction rate constant of kSUGM,s = 4.75 × 10–3 min–1 with τ0.5 = 130.3 min is calculated for the chemical reactivity of the rate limiting step. The high catalytic activity of the K2CO3 catalyst was reduced here by forming a K2O × SiO2 species. An oxygen transfer via a catalytic active potassium intercalate by forming a oxygenated C(O) intermediate is proposed to describe the reaction mechanism of the gasification process in the presence of a stable and non-stable catalyst.

Reduction of the Probability of Occurrence of Differential Pressure Sticking Through the Use of Diesel on Water Based Drilling Fluids

The drilling campaign on Pad C of the Tiputini Field, located on the Oriente Basin, Ecuador, started with the first exploratory well TPTC-002. Pressure tests performed on the M1 sandstone of the Napo Formation determined that the average reservoir pressure (Pr) was 1921 psi. Ten months later, Pr averaged 846 psi. This increased the risk of differential pressure sticking, event that indeed occurred while drilling the well TPTC-016. By using the “Bow-Tie” methodology as a predictive tool to analyze risks, and taking into account the preliminary studies that describe this phenomena, a solution was found for stablishing an additional barrier with the use of diesel on the water-based drilling fluid. Diesel was used in order to extend the ‘half value time’ and to decrease the friction coefficient between the mud cake and pipe.

Simplicity Driven Application Development

In this article we discuss a simplicity-oriented approach to application development along a case study for engineering a web platform for orchestrating predefined service modules. Focus here is the growing demand for agility: 1) earlier solutions typically economically outperform later, more mature solutions, and 2) the half-value times of applications are drastically shrinking. Our simplicity-oriented approach therefore addresses both, the ease of application development, exploiting the so-called 80/20 principle, and the ease of take-up, aiming at removing potential hurdles for user adoption. We will discuss how this reflects on design decisions, in particular concerning the sweet spot where to change from adopting and adapting existing software to custom development.

Anomalous transport resolved in space and time by fluorescence correlation spectroscopy

A ubiquitous observation in crowded cell membranes is that molecular transport does not follow Fickian diffusion but exhibits subdiffusion. The microscopic origin of such a behaviour is not understood and highly debated. Here we discuss the spatio-temporal dynamics for two models of subdiffusion: fractional Brownian motion and hindered motion due to immobile obstacles. We show that the different microscopic mechanisms can be distinguished using fluorescence correlation spectroscopy (FCS) by systematic variation of the confocal detection area. We provide a theoretical framework for space-resolved FCS by generalising FCS theory beyond the common assumption of spatially Gaussian transport. We derive a master formula for the FCS autocorrelation function, from which it is evident that the beam waist of an FCS experiment is a similarly important parameter as the wavenumber of scattering experiments. These results lead to scaling properties of the FCS correlation for both models, which are tested by in silico experiments. Further, our scaling prediction is compatible with the FCS half-value times reported by Wawrezinieck et al. [Biophys. J. 89, 4029 (2005)] for in vivo experiments on a transmembrane protein.

Gastric Emptying of Preterm Neonates Receiving Domperidone

Objectives: Immature gut motility in very low birth weight infants causes feeding intolerance. We evaluated the effect of domperidone, a prokinetic agent, on gastric emptying in very low birth weight infants. Methods: The study was conducted in a crossover design. Gastric emptying was assessed ultrasonographically by measuring the time it took the antral cross sectional area of the stomach to reach half of the value of the 1st measurement on 2 occasions: (1) upon administration of domperidone (0.3 mg/kg/8 h p.o.) for at least 2 days and (2) while patients received an equal quantity of sterile water. 11 infants were randomly assigned to receive domperidone before the 1st measurement and the remaining afterwards. There was a 3–5 day interval between the 2 measurements. At the time when both measurements were performed, every neonate had been receiving the same quantity and quality of milk. 12 infants were formula-fed while 10 were fed their own mother’s supplemented milk. Results: 22 infants with a mean (SD) birth weight of 1,377 g (319) and a mean (SD) gestational age of 30.2 weeks (2.1) were studied. The mean (SD) antral cross sectional area half-value time (in minutes) was 47.6 (23.9) in the domperidone group and 68.2 (25.5) in the control group (p = 0.008). There was no significant difference between formula-fed neonates and neonates fed their own mother’s milk in either group. Conclusions: Domperidone significantly reduces gastric emptying in preterm neonates, and this may account for its effect in cases of disturbances related to gut motility.

Transgenerational accumulation of radiation damage in small mammals chronically exposed to Chernobyl fallout

The purpose of this investigation has been the analysis of the long-term development of biological damage in natural populations of a model mammalian species, the bank vole (Clethrionomys glareolus, Schreber), which were chronically exposed to low doses of ionizing radiation over 22 animal generations within 10 years following the Chernobyl accident. The time course of the biological end-points (chromosome aberrations in bone marrow cells and embryonic lethality) was compared with the time course of the whole-body absorbed dose rate from external and internal exposure in the studied populations inhabiting monitoring sites in Belarus with different ground deposition of radionuclides. The yield of chromosome aberrations and, in lesser degree, embryonic lethality was associated with the radionuclide contamination of the monitoring areas in a dose-dependent manner. As a main feature of the long-term development of biological damage under low dose rate irradiation, permanently elevated levels of chromosome aberrations and an increasing frequency of embryonic lethality have developed over 22 animal generations. This contrasts with the assumption that the biological damage would gradually disappear since in the same period of time the whole-body absorbed dose rate decreased exponentially with a half-value time of about 2.5-3 years. Furthermore, gravid females were captured, and their offspring, born and grown up under contamination-free laboratory conditions, showed the same enhanced level of chromosome aberrations. Therefore the authors suggest that, along with the biological damage attributable to the individual exposure of each animal, the observed cellular and systemic effects reflect the transgenerational transmission and accumulation, via genetic and/or epigenetic pathways, of damage attributable to the chronic low-dose rate exposure of the preceding generations of animals. They also suggest that the level of the accumulated transmissible damage in the investigated populations will decrease in future due to the further recession of the chronic exposure and as a consequence of selection processes.

Dispersion and stability of silver inks

Different dispersants were used to develop ethanol-based silver inks for continuous ink-jet printing. Inks were made using varying amounts of dispersant and silver. Various parameters, such as sedimentation behaviour, sediment volume, half-value time and viscosity, were used to assess the dispersion and stability of these inks over 10 days.

A method to measure thermal conductivity and thermal diffusivity under pore and confining pressure

A measuring equipment was developed for the determination of thermal conductivity and thermal diffusivity of rocks under pore and confining pressure up to 90 MPa and 300 MPa, respectively. A quadratic heater placed between two cubic samples generates a rectangular heat pulse of 5 s length. In one of the cubes the pulse response at a known distance from the heater is measured by a thermocouple. The sample holder is mounted on the upper plug of the used high pressure vessel. The whole sample arrangement is sealed against the pressure medium by an elastic polyurethene jacket. Pore fluid is introduced into the pore space of the rock sample by a perforated back plate. A numerical modelling of the pulse propagation is used to determine thermal conductivity and thermal diffusivity from the measured pulse amplitude and half value time. First results are given for a 16 % porosity sandstone from Obernkirchen, Germany.

Morphometric study on the postnatal growth of the hippocampus in Australian Aborigines and Caucasians

In an autopsy study on Australian Aborigines (29 males, 27 females) and Caucasians (57 males, 37 females) the postnatal growth of the hippocampus was studied and described by mathematical growth functions. For male adults no significant difference in hippocampal volume was found. In contrast, hippocampal volume was significantly smaller for Aboriginal females compared to Caucasian females. Growth analysis showed slower growth rates and later half-value times for Aborigines compared to Caucasians. These results are discussed in relation to secular changes of growth parameters of the human brain during the last century, the socioeconomic and health status of Aborigines, and sexual differences in development and plasticity of the hippocampus.

Morphometric study on the postnatal growth of the cerebellum of Australian Aborigines and Caucasians

In an autopsy study on 29 male Aborigines and 57 male Caucasians, macroscopic and microscopic parameters of postnatal cerebellar development were determined and described by mathematic growth functions. For the whole cerebellum and its cortical layers volume measurments revealed delayed maturation for Aborigines compared to Caucasians. Despite the slower development in childhood, significantly smaller values for adult Aborigines compared to Caucasians were observed only for the whole cerebellum and the Purkinje cell sheet. Similarly, postnatal changes in Purkinje cell size showed prolonged growth phases in Aborigines compared to Caucasians. Calculations of absolute cell numbers for individual layers demonstrated later half-value times and slower growth rates for cell numbers in the internal granular and molecular layers consistent with the findings for the corresponding layer volumes. For Caucasians, the growth curve for the absolute cell number in the internal granular layer showed a maximum about 21 months postnatally and subsequently decreased towards adulthood by about 18%. No such overshoot could be demonstrated for Aborigines. In relation to absolute cell numbers in adulthood, this could indicate a smaller number of granule cells migrating from the external to the internal granular layer as well as less pronounced granule cell death in Aborigines compared to Caucasians. The external granular layer of Caucasians increased in volume postnatally to reach a maximum at about 4 months and subsequently decreased until its disappearance at approximately 2 years of age. The number of Purkinje cells decreased marginally postnatally in both populations. These results were discussed in relation to secular changes of growth parameters of the cerebellum during the last century and the socioeconomic and health status of Aborigines.

Morphometric study on the postnatal growth of non-cortical brain regions in Australian Aborigines and Caucasians

In an autopsy study on 29 male and 27 female Aborigines and 57 male and 37 female Caucasians the volumes of a large number of brain regions were determined and fitted to logistic growth functions. For Aboriginal adults significantly smaller values were found for weight and volume of the whole brain, cerebrum, and cerebellum and for the volumes of cerebral white matter, thalamus, amygdaloid body (females only), and globus pallidus (males only). No significant differences were found for caudate nucleus, putamen, amygdaloid body (males only), and globus pallidus (females only). Almost every region studied showed later half-value times, slower growth rates, and prolonged growth phases for Aborigines compared to Caucasians. These results are discussed in relation to secular changes of growth parameters of the human brain during the last century, timing of growth phases for each area, and the socioeconomical and health status of Aborigines.

Insecticide metabolism and partition in isolated organs of house fly larvae and adults

Isolated organs of larvae and adults of house flies were incubated in nutrient solutions to study uptake and metabolism of insecticides. Single organs were incubated in solutions of radiolabeled paraoxon, methyl-paraoxon, parathion, and tetrachlorvinphos. Larval fatbody, consisting of a single layer of large cells, was studied most extensively. Uptake and release of the insecticides led to the same partition between solution and organ. This was not so in adult gut or abdominal body wall. Partition between fatbody and solution was 2250, 370, and 11 for parathion, tetrachlorvinphos, and paraoxon, respectively. Release of insecticide into the medium followed first-order kinetics. Rate of equilibration was slowest for tetrachlorvinphos (half value time 17 min). Parathion exchanged faster and paraoxon fastest (half value < 1 min). Metabolism was mainly studied in two strains Fc and Nic with polysubstrate monooxygenases causing resistance to paraoxon and other insecticides, and in a tetrachlorvinphos resistant strain CH with high GSH 2S-transferase activity. Oxygenase activity varied widely between individual larvae, the variation being at least partly genetic. Sesamex and parathion inhibited paraoxon metabolism. Transferase activity in fatbodies of CH was maximally 8 nmol tetrachlorvinphos/hour, whereas larvae in vitro had an activity of 52 nmol/hour. Incubation of isolated organs is well stuited for genetic studies on detoxication capacity since it enables the study of metabolism in individual small insects. Its merits and limitations for toxicological analysis are discussed.

COMBINED VENTILATION AND PERFUSION SCANNING OF THE LUNG IN CHILDREN WITH BRONCHOPULMONARY DISEASES

The combined ventilation and perfusion scanning with 133Xe-gas and 99mTo Human albumin microspheres was carried out in 133 children at the age from 1 month to 16 years. The findings were compared with clinical x-ray and bronchologic ones as well as with parameters for the function of the lung FVC and FEV1.0. In children with bronchiectasia (n = 24) there exist distinct perfusion and exhale disturbances in form of trapped gas, reduced exhalation and half value time of the 133Xe-clearance in the bronchiectasial areas, proved bronchographically. In children with deforming bronchitis (n = 18) we only observed slight perfusion disturbances and twice discreet exhale troubles without trapped gas. In children with cystic fibrosis (n = 26) regional obstructions could prematurelly be proved, they were not yet caught spirometrically. Typical findings were diffuse perfusion - and ventilation disturbances (trapped gas) mainly in the apex areas. With agenesia of A. pulmonalis we observed no perfusion and reduced FRC of the side affected with no abnormality in exhaling, as well as in case with agenesia of the lung an absent perfusion and ventilation.

Active sulfate reabsorption in the proximal convolution of the rat kidney: specificity, Na+ and HCO3- dependence.

Using the standing droplet technique in the proximal convolution and simultaneous microperfusion of the peritubular capillaries, the decrease in luminal sulfate concentration with time and the zero net flux transtubular concentration difference of sulfate (delta CSO42-) at 45 s was determined - the latter being taken as a measure of the rate of active sulfate reabsorption. Starting with 0.5 mmol/l sulfate in both perfusates the delta CSO42- value of 0.35 mmol/l was approached exponentially with a half value time of 4.3 s. The delta CSO42- values in the early proximal and late proximal convolution did not deviate from each other. If the Na+ concentration in the perfusates was reduced, the delta CSO42- approached zero and extrapolated to a slightly negative value (Ci greater than Co). When 1 mmol/l ouabain was added to the perfusates delta CSO42- decreased by 66% (the latter experiments were performed in the golden hamster which is more sensitive to ouabain than the rat). 1 mmol/l thiosulfate diminished delta CSO42- by 68% and 1 mmol/l molybdate by 24%. Omitting or replacing bicarbonate by HEPES or glycodiazine reduced the sulfate reabsorption significantly, while acetazolamide (0.1 mmol/l) and increasing the CO2-pressure from 4.66 to 14.0 kPa (i.e. 5-15% CO2) had no effect. SITS 1 mmol/l had no effect on sulfate reabsorption. The data indicate that the sulfate reabsorption is driven by a Na+ gradient and inhibited by thiosulfate and molybdate, i.e. molecules which have a similar tetrahedral molecule structure. The sulfate reabsorption depends in an undefined manner on the presence of bicarbonate ions.

Beurteilungskriterien der hepatobiliären Funktionsszintigraphie mit99mTc-markiertem Diäthyl-IDA — Befunde bei Lebergesunden

Hepato-biliary functional scintigraphy was performed on 51 patients with normal livers after in the injection of 99mTc diethyle-IDA. The results were analysed according the morphological criteria (demonstration of the bile duct, intra-hepatic ducts, gall bladder and renal tract) and functional criteria (T max, half-time biliary excretion values, development of activity in the bile duct, in the gall bladder and in the gut). Demonstration of the bile duct and gall bladder was successful in all cases if the examination was carried out after an appropriate interval following food. 84.3% of patients showed a gall bladder excretary pattern of the tracer and 15.7% a gall bladder storage pattern. Correspondingly, bile appeared in the duodenum at 16.5 +/- 6.5 minutes (excretion) or 79.3 +/- 49.5 minutes (storage). The left hepatic duct was shown in 58.8%, the right hepatic duct in only 58.8%. Sixty minutes after the injection no activity could be determined in the bile ducts beyond the liver parenchyma. The gall bladder could be identified after 26.6 +/- 24.4 minutes, occasionally it was much later, up to 110 minutes. The liver function curve showed a Tmax level of 6.8 +/- 2.7 minutes and half value time of 15.8 +/- 6.7 minutes. At 5 minutes after injection the renal pelvis could be identified in 19.6%, but in no case was this still present beyond 15 minutes. Duodeno-gastric reflux was not demonstrated.

Functional gastric diagnosis (author's transl)

A method is described (isotope gastro-diagram) in which a radio-active labelled standard meal is used under physiological and phatological conditions; in this way the half-value time of gastric emptying can be used as an objective measure of gastric motor function, and which can be easily reproduced. This has become of clinical interest, particularly since the introduction of hypotonic and double contrast methods in radiological diagnosis. The clinical value of this method has been elucidated amongst surgical patients on whom pre- and post-operative measurements were carried out following selective vagotomies, combined with various types of pyloroplastry for the treatment of gastric and duodenal ulcers.