Method For Determination Of Rates Research Articles

A Green Method to Determine VUV (185 nm) Fluence Rate Based on Hydrogen Peroxide Production in Aqueous Solution

A mini-fluidic vacuum ultraviolet/ultraviolet (VUV/UV) photoreaction system (MVPS) was developed in our previous study. Based on the MVPS, a green method to determine VUV fluence rate has been developed using the production rate of H2 O2 when water is exposed to 185nm VUV. The H2 O2 production followed pseudo-zero-order reaction kinetics well over the first 10min of VUV/UV exposure. This new method was well calibrated with a standard cis-cyclooctene cis-trans photoisomerization actinometer as recommended by the International Union of Pure and Applied Chemistry. The apparent quantum yield for H2 O2 production by 185nm VUV irradiation of water was determined to be 0.024±0.002. As the solution pH increased from 5.0 to 8.0, the H2 O2 production rate decreased from 0.83 to 0.40μmmin-1 . Dissolved oxygen had a negligible influence on the H2 O2 production. This study proposes a novel VUV fluence rate determination method with advantages of nontoxicity, low detection limits, low costs and convenience, and it can be used as a good alternative to traditional actinometers.

Quantifying Reversible Surface Binding via Surface-Integrated Fluorescence Correlation Spectroscopy.

We present a simple and versatile single-molecule-based method for the accurate determination of binding rates to surfaces or surface bound receptors. To quantify the reversible surface attachment of fluorescently labeled molecules, we have modified previous schemes for fluorescence correlation spectroscopy with total internal reflection illumination (TIR-FCS) and camera-based detection. In contrast to most modern applications of TIR-FCS, we completely disregard spatial information in the lateral direction. Instead, we perform correlation analysis on a spatially integrated signal, effectively converting the illuminated surface area into the measurement volume. In addition to providing a high surface selectivity, our new approach resolves association and dissociation rates in equilibrium over a wide range of time scales. We chose the transient hybridization of fluorescently labeled single-stranded DNA to the complementary handles of surface-immobilized DNA origami structures as a reliable and well-characterized test system. We varied the number of base pairs in the duplex, yielding different binding times in the range of hundreds of milliseconds to tens of seconds, allowing us to quantify the respective surface affinities and binding rates.

A simplified implementation of the stationary liquid mass balance method for on‐line OUR monitoring in animal cell cultures

AbstractBACKGROUNDCompared with other methods, the stationary liquid mass balance method for oxygen uptake rate (OUR) determination offers advantages in terms of estimation accuracy and reduction of stress. However, the need for sophisticated instrumentation, like mass flow controllers and gas analysers, has historically limited wider implementation of such a method.In this paper, a new simplified method based on inexpensive valves for the continuous estimation of OUR in animal cell cultures is evaluated. The determination of OUR values is based on accurate operation of the dissolved oxygen (DO) control loop and monitoring of its internal variables.RESULTSThe method developed was tested empirically in 2 L bioreactor HEK293 batch cultures. OUR profiles obtained by a dynamic method, global mass balance method and the developed simplified method were monitored and compared. The results show how OUR profile obtained with the proposed method better follows the off‐line cell density determination. The OUR estimation frequency was also increased, improving the method capabilities and applications.The theoretical rationale of the method was extended to the sensitivity analysis which was analytically and numerically approached.CONCLUSIONSThe results showed the proposed method to be not only cheap, but also a reliable alternative to monitor the metabolic activity in bioreactors in many biotechnological processes, being a useful tool for high cell density culture strategies implementation based on OUR monitoring. © 2017 Society of Chemical Industry

Application of Hierarchical Model in Non-Life Insurance Actuarial Science

Loss data structures in non-life insurance businesses are increasingly complex, and the tendency of correlation and heterogeneity is gradually presented. Hierarchical model can breakthrough limitation that the traditional rate determination method only analyzes the loss data of the same insurance policy; meanwhile, the accuracy of complex structure data prediction is improved. This paper, using a hierarchical generalized linear model, studies the non-life rate determination of multi-year loss data and takes auto insurance data for empirical analysis. The research results show that GLMM’s fitting degree is greatly improved compared with GLM, considering the random effects. It can more effectively reflect different risk individual differences and also reveal the heterogeneity and correlation of risk individual loss during multiple insurance periods.

Ventilation rate determination method for residential buildings according to TVOC emissions from building materials

People spend most of their time indoors in residential buildings; thus, maintaining good indoor air quality (IAQ) is essential. It is necessary to provide a suitable ventilation rate in these spaces (low-density occupation) taking into account that materials (finishes and furnishing) are one of the main sources of indoor pollution. For that purpose, this research, based on both the National Research Council (NRC) database and a specific case study, followed a method that consisted of the identification of indoor pollution sources, evaluation of the emission factor and characterization of the IAQ. It is intended to show the influence of materials (quantity, type and age), loading ratio and pollution concentration threshold in the calculation of a ventilation rate which guarantees a good IAQ. This study also reflects the need to bring together an overall pollution concentration threshold of TVOC, below which a safe level of exposure to indoor pollution is recognized.

A Fast Electro-Thermal Model of Traction Inverters for Electrified Vehicles

In this paper, a fast electro-thermal model of traction inverters for electrified vehicles is proposed. First, a thermal model considering the thermal coupling is presented and experimentally verified. The impact of the thermal spreading effect, heat convection, and temperature-dependent material thermal properties on the accuracy of the linear assumption is investigated by ANSYS-Fluent simulation. In order to reduce the influence of the temperature-dependent thermal conductivity on the accuracy of the thermal model, the average temperature is applied to determine the thermal conductivity of the power module package. Second, an accurate temperature-dependent switching power loss model is represented as the lookup table through experimental measurements. In order to simplify the lookup table, the switching power loss is considered proportional to the dc-link voltage and, therefore, the inputs of the lookup table are current and temperature. Finally, a scheme to speed up the online junction temperature estimation is proposed by considering both the thermal network properties and the required accuracy. With the proposed calculation rate determination method, the total computational time for the junction temperature estimation is reduced significantly.

Evolution of Machine Reliability and Life and Economics of Operational Use

Abstract The article presents new assumptions for reliability and life of machines, resulting from the development of technology. The innovative approach to reliability and life design as well as warranty duration planning is presented on an example of vehicle reliability characteristics. A new algorithm is proposed for the replacement of repairable objects costs by the price of life and reliability of new unrepairable ones. For the planning of the life of innovative machines, an effective method of technical progress rate determination is proposed. In conclusion, necessary modifications of machine and vehicle use systems, resulting from technology evolution and technical progress, are indicated. Finally, recommendations and directions of indispensable research in engineering and management of technical means of production are formulated.

Photobiomodulation therapy reduces apoptotic factors and increases glutathione levels in a neuropathic pain model.

Neuropathic pain (NP) is caused by damage to the nervous system due to reactive oxygen spices (ROS) increase, antioxidants reduction, ATP production imbalance, and induction of apoptosis. In this investigation, we applied low-level laser 660nm (photobiomodulation therapy) as a new strategy to modulate pain. In order to study the effects of photobiomodulation therapy (660nm) on NP, chronic constriction injury (CCI) model was selected. Low-level laser of 660nm was used for 2weeks. Thermal and mechanical hyperalgesia were measured before and after surgery on days 7 and 14, respectively. Paw withdrawal thresholds were also evaluated. Expression of p2x3, Bax, and bcl2 protein was measured by western blotting. The amount of glutathione (GSH) was measured in the spinal cord by continuous spectrophotometric rate determination method. The results are presented as mean ± SD. Statistical analysis of data was carried out using SPSS 21. CCI decreased the pain threshold, 2-week photobiomodulation therapy significantly increased mechanical and thermal threshold, decreased P2X3 expression (p < 0.001), and increased bcl2 expression (p < 0.01), but it was not effective on the Bax expression. We speculated that although photobiomodulation therapy increased ROS generation, it increased antioxidants such as GSH. Increase in bcl2 is another mitochondrial protection mechanism for cell survival and that pain relief and decrease in P2X3 expression confirm it.

Effects of 660nm Low-Level Laser Therapy on P2X3 Expression of Lumbar DRG of Adult Male Rats with Neuropathic Pain

Background: Neuropathic Pain (NP) is a serious suffering medical condition that frequently leads to disability and life style changes. Although the exact mechanisms of NP are still unknown, recently the role of reactive oxygen species (ROS) reported as an important factor for NP. Apoptosis, increase of ATP production and reduction of antioxidants are also the other factors influencing in NP. There are certain therapeutic procedures for NP among them using laser therapy newly received more attention. In the present research we studied the molecular effects of Low Level Laser Therapy (LLLT) on a rat model of NP. Methods: Thirty adult male Wistar rats (200-250 g) that randomly divided into three groups including chronic constriction injury (CCI), CCI+LLLT and control were used in this study. CCI technique was used to induce NP. Laser therapy was done by using laser beam of 660 for 14 days following CCI. After that, expression of P2X3 of the DRG, Bax and Bcl2 in lumbar spinal segments measured by Western Blotting. Level of glutathione (GSH) was also measured in lumbar spinal cord segments by Continuous Spectrophotometric Rate Determination method. For behavioral study the mechanical and thermal hyperalgesia were evaluated in days 7 and 14 after CCI. Results: LLLT for two weeks increased expression of Bcl 2 and GSH, whereas decreased Bax and P2X3 expression significantly. Comparing the results of behavioral study showed significant differences in the mechanical and thermal threshold showed between CCI and CCI+ LLLT groups. Conclusion: Based on our findings, the therapeutic effects of LLLT for NP act throughout cellular and molecular mechanisms which improve mitochondrial function that in turn improve cell function and prevent apoptosis.

Gravimetric Measurement of Hydrogen Evolution on Magnesium

The aim of this work is to study the suitability and limitations of a new gravimetric hydrogen evolution (HE) collection method for corrosion rate determination on pure Mg. This method, originally developed by Curioni [1], is based on the real-time weight measurement of the H2 produced during dissolution and exhibits a higher accuracy level as well as better collection efficiency than the traditional volumetric method. The gravimetric HE collection method overcomes some of the limitations exhibited by the traditional volumetric HE method, where hydrogen gas tends to accumulate at the walls of the funnel and the burette, leading to a lower determination of the amount of H2 produced and thus, an underestimation of the HE rate. The gravimetric HE collection method also exhibits good suitability for the study of Mg alloys with high corrosion resistance and for short experimental times, where the low levels of H2 produced prevents reliable measurements of the amount of gas evolved by the volumetric HE collection method. The gravimetric HE collection method is also applicable for dynamic measurements, i.e. potentiodynamic and galvanodynamic polarizations. The gravimetric method was evaluated for the study of anodic HE on pure Mg (also termed Negative Difference Effect (NDE)), which is characteristic of Mg and its alloys when they are forced to dissolve at anodic potentials from the E corr. Possible artifacts and experimental limitations of the gravimetric experimental method will be discussed. [1] M. Curioni, The behaviour of magnesium during free corrosion and potentiodynamic polarization investigated by real-time hydrogen measurement and optical imaging, Electrochim. Acta 120 (2014) 284-292.

A preliminary ventilation rate determination methods study for residential buildings and offices based on VOC emission database

Ventilation is commonly used as a basic means to supply outdoor air to indoor environment to achieve better indoor air quality. To reduce harmful effect due to indoor pollutants such as formaldehyde and VOCs emitted from building materials, proper ventilation should be maintained to meet a minimum ventilation rate at least. Two new methods, i.e., characteristic and two-stage ventilation rate method, were proposed to predict ventilation rate based on building material emissions. Scenarios involving four standard rooms and different material loadings were analyzed to study adequate ventilation rates for residential buildings and offices. The study followed the IAQ procedure recommended by ASHRAE. The emission source data were from the National Research Council Canada (NRC) database. The building material emissions and consequent VOC concentrations were predicted by using two approaches called the characteristic emission rate method and the two-stage emission rate method. The ventilation rates were calculated for ten scenarios to meet the thresholds given by seven indoor air quality references. The results showed that the ventilation rate depended on the selection of reference standard, material and emission area. The dominating chemical substance in determining ventilation rate in various cases was not unique. The time to take for the emission to complete was 2.5–5 years for all cases. Due to the inherent nature of the characteristic emission rate method for over-estimating long-term emissions, replacing the characteristic ventilation rate with steady-state ventilation rate could lead to the ventilation rate requirement reduced by approximately half.

A mathematical method for extracting cell secretion rate from affinity biosensors continuously monitoring cell activity.

Our laboratory has previously developed miniature aptasensors that may be integrated at the site of a small group of cells for continuous detection of cell secreted molecules such as inflammatory cytokine interferon gamma (IFN-γ). In a system such as this, the signal measured at the sensor surfaces is a complex function of transport, reaction, as well as of cellular activity. Herein, we report on the development of a mathematical framework for extracting cell production rates from binding curves generated with affinity biosensors. This framework consisted of a diffusion-reaction model coupled to a root finding algorithm for determining cell production rates values causing convergence of a predetermined criterion. To experimentally validate model predictions, we deployed a microfluidic device with an integrated biosensor for measuring the IFN-γ release from CD4 T cells. We found close agreement between secretion rate observed theoretically and those observed experimentally. After taking into account the differences in sensor geometry and reaction kinetics, the method for cell secretion rate determination described in this paper may be broadly applied to any biosensor continuously measuring cellular activity.

A novel murine model of Fusarium solani keratitis utilizing fluorescent labeled fungi

Fungal keratitis is a common disease that causes blindness. An effective animal model for fungal keratitis is essential for advancing research on this disease. Our objective is to develop a novel mouse model of Fusarium solani keratitis through the inoculation of fluorescent-labeled fungi into the cornea to facilitate the accurate and early identification and screening of fungal infections. F. solani was used as the model fungus in this study. In in vitro experiment, the effects of Calcofluor White (CFW) staining concentration and duration on the fluorescence intensity of F. solani were determined through the mean fluorescence intensity (MFI); the effects of CFW staining on the growth of F. solani were determined by the colony diameter. In in vivo experiment, the F. solani keratitis mice were induced and divided into a CFW-unlabeled and CFW-labeled groups. The positive rate, corneal lesion score and several positive rate determination methods were measured. The MFIs of F. solani in the 30 μg/ml CFW-30 min, 90 μg/ml CFW-10 min and 90 μg/ml CFW-30 min groups were higher than that in the 10 μg/ml CFW-10 min group (P < 0.01). Compared with the 30 μg/ml CFW-30 min group, only the 90 μg/ml CFW-30 min group showed higher MFI (P < 0.05). No significant difference was observed in the colony diameter in the CFW unstained group compared with that in the 10, 30, 90, 270, or 810 μg/ml CFW groups stained for either 10 or 30 min (P > 0.05). No significant differences (P > 0.05) were observed for the positive rate or the corneal lesion scores between the CFW-unlabeled and the CFW-labeled group. On day 1 and 2, the positive rates of the infected corneas in the scraping group were lower than those in the fluorescence microscopy group (P < 0.05). On day 3, these observe methods showed no significant difference (P > 0.05). Thus, these experiments established a novel murine model of F. solani keratitis utilizing fluorescent labeled fungi. This model facilitates the accurate identification and screening of fungal infections during the early stages of fungal keratitis and provides a novel and reliable technology to study the fungal keratitis.

Corrosion and Inhibition Effects of Mild Steel in Hydrochloric Acid Solutions Containing Organophosphonic Acid

A study has been made on the mechanism of corrosion of mild steel and the effect of nitrilo trimethylene phosphonic (NTMP) acid as a corrosion inhibitor in acidic medium, that is, 10% HC1 using the weight loss method and electrochemical techniques, that is, potentiodynamic and galvanostatic polarization measurements. Although corrosion is a long-time process, but it takes place at a faster rate in the beginning which goes on decreasing with due course of time. The above-mentioned methods of corrosion rate determination furnish an average value for a long-time interval. Looking at the versatility and minimum detection limit of the voltammetric method, the authors have developed a new voltammetric method for the determination of corrosion rate at short-time intervals. The results of corrosion of mild steel in 10% HC1 solution with and without NTMP inhibitor at short-time intervals have been reported. The corrosion inhibition efficiency of NTMP is 93% after 24 h.

A high-throughput seed germination assay for root parasitic plants

BackgroundSome root-parasitic plants belonging to the Orobanche, Phelipanche or Striga genus represent one of the most destructive and intractable weed problems to agricultural production in both developed and developing countries. Compared with most of the other weeds, parasitic weeds are difficult to control by conventional methods because of their life style. The main difficulties that currently limit the development of successful control methods are the ability of the parasite to produce a tremendous number of tiny seeds that may remain viable in the soil for more than 15 years. Seed germination requires induction by stimulants present in root exudates of host plants. Researches performed on these minute seeds are until now tedious and time-consuming because germination rate is usually evaluated in Petri-dish by counting germinated seeds under a binocular microscope.ResultsWe developed an easy and fast method for germination rate determination based on a standardized 96-well plate test coupled with spectrophotometric reading of tetrazolium salt (MTT) reduction. We adapted the Mosmann’s protocol for cell cultures to germinating seeds and determined the conditions of seed stimulation and germination, MTT staining and formazan salt solubilization required to obtain a linear relationship between absorbance and germination rate. Dose–response analyses were presented as applications of interest for assessing half maximal effective or inhibitory concentrations of germination stimulants (strigolactones) or inhibitors (ABA), respectively, using four parameter logistic curves.ConclusionThe developed MTT system is simple and accurate. It yields reproducible results for germination bioassays of parasitic plant seeds. This method is adapted to high-throughput screenings of allelochemicals (stimulants, inhibitors) or biological extracts on parasitic plant seed germination, and strengthens the investigations of distinctive features of parasitic plant germination.

A novel technique for fetal heart rate estimation from Doppler ultrasound signal

BackgroundThe currently used fetal monitoring instrumentation that is based on Doppler ultrasound technique provides the fetal heart rate (FHR) signal with limited accuracy. It is particularly noticeable as significant decrease of clinically important feature - the variability of FHR signal. The aim of our work was to develop a novel efficient technique for processing of the ultrasound signal, which could estimate the cardiac cycle duration with accuracy comparable to a direct electrocardiography.MethodsWe have proposed a new technique which provides the true beat-to-beat values of the FHR signal through multiple measurement of a given cardiac cycle in the ultrasound signal. The method consists in three steps: the dynamic adjustment of autocorrelation window, the adaptive autocorrelation peak detection and determination of beat-to-beat intervals. The estimated fetal heart rate values and calculated indices describing variability of FHR, were compared to the reference data obtained from the direct fetal electrocardiogram, as well as to another method for FHR estimation.ResultsThe results revealed that our method increases the accuracy in comparison to currently used fetal monitoring instrumentation, and thus enables to calculate reliable parameters describing the variability of FHR. Relating these results to the other method for FHR estimation we showed that in our approach a much lower number of measured cardiac cycles was rejected as being invalid.ConclusionsThe proposed method for fetal heart rate determination on a beat-to-beat basis offers a high accuracy of the heart interval measurement enabling reliable quantitative assessment of the FHR variability, at the same time reducing the number of invalid cardiac cycle measurements.

A method for determination of emission rates from SO2 sheets for storage of grapes

Introduction Table grapes are very susceptible to decay caused by Botrytis cinerea during storage, and one of the common means to control decay is by packaging the fruit with a SO2-generating sheet. Typically, the sheets contain sodium metabisulphite in a granulated form that releases SO2 upon absorption of water in two phases: a fast-release phase of high SO2 level and a slow, continual release of a low level of SO2. Objective Currently, there is no published method to compare or validate the performance of different SO2 sheets. This paper describes a simple analytical method to quantify the rate of SO2 release from the sheets which does not require setting up storage experiments with grapes. Results The method was used to test the total amount of SO2, which was released under the experimental conditions. However, most of the study was focused on a relative measurement that can help with comparing different SO2 sheets or the same sheets from different production dates. Conclusion The method revealed significant differences in SO2 release pattern between different types of SO2 sheets or the same sheets from different years of production. The method can allow grape growers to have better tools that will ensure successful control of decay during storage.

Alternative method for angular rate determination within the GOCE gradiometer processing

The most crucial part of the GOCE gradiometer processing is, besides the internal calibration of the gradiometer, the determination of the satellite’s inertial angular rate. This paper describes a new method for the angular rate determination. It is based on the stochastic properties of the GOCE star sensors and the gradiometer. The attitude information of both instrument types is combined at the level of angular rates. The combination is done in the spectral domain by Wiener filtering, and thus using an optimal relative weighting of the star sensor and gradiometer attitude information. Since the complete processing chain from raw measurements to gravity field solutions is performed, the results are not only analyzed at the level of gravity gradients, but also of gravity field solutions. Compared to the nominal method, already the resulting gravity gradients show a significantly improved performance for the frequencies (mainly) below the gradiometer measurement bandwidth. This can be verified by analysis of the gravity gradient trace. The improvement is propagated to the level of gravity field models, where a better accuracy can be observed for selected groups of coefficients at characteristic bands at orders k × 16, with integer k, up to high harmonic degrees.

Corrosion inhibition of copper in HNO3 solution using thiophene and its derivatives

The corrosion behavior of copper in the presence of thiophene (T) and some of its derivatives [2-thiophene carboxylic acid (TC) and 2-thienyl ethanol (TE)] has been investigated in 2M HNO3 solution using electrochemical frequency modulation (EFM), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and weight loss techniques. Polarization studies showed that these compounds act as mixed type inhibitors. EFM technique provides a new tool for electrochemical corrosion monitoring and was used as an effective method for corrosion rate determination. In EFM measurements corrosion current density was determined without prior knowledge of Tafel slopes. Inhibition efficiency of these compounds has been found to vary with concentrations of the compounds and temperature. The adsorption of these compounds on the copper surface from the acid solution has been found to obey Langmuir adsorption isotherm. The thermodynamic activation parameters of copper corrosion in 2M HNO3 were determined and discussed. The results obtained from EFM, EIS, Tafel and weight loss measurements were in good agreement.

Dating mortar by optically stimulated luminescence: A feasibility study

Quartz is the datable component in mortar. Although its luminescence properties are very well studied, the problem of mortar dating arises from a low level of optical bleaching. In order to reduce the time consuming efforts for dating lime mortar in monuments by optically stimulated luminescence, we investigated the most suitable methods of dose and dose rate determination, and we explored tests which are suitable to predict the datability of a given material. Reverting to the large number of publications on sedimentary partially bleached quartz we found linear modulation techniques especially useful, equally we also recommend the determination of the level of optical depletion before starting analyses. Single grain analysis is regarded as an ultimate but infallible tool to date very poorly bleached quartz from mortar. Dose rate measurements need to take into account the radioactive equilibrium of the uranium decay and the short range inhomogeneity of the environmental gamma radiation field: gamma spectrometry and on-site TLD measurements are best suited.