A new system for measuring low-ohmic standard resistors through a dual current sources bridge is introduced.It is used for low resistance measurements from 1 mΩto 1Ωat 1∶1 ratio,which is suitable for the laboratori...A new system for measuring low-ohmic standard resistors through a dual current sources bridge is introduced.It is used for low resistance measurements from 1 mΩto 1Ωat 1∶1 ratio,which is suitable for the laboratories without cryogenic current comparators(CCC)or direct current comparators(DCC)bridges.Behavior of this bridge is evaluated by comparing its measured values with the unknown resistor values obtained by another method.The accuracy of the introduced bridge is in the level of 10-5 for the 1 mΩresistor,and in the level of 10-4 for the 10 mΩ,100 mΩand 1Ωresistors.Moreover,a dual voltage sources system for the measurement of DC standard resistors from 1 kΩto 100 MΩis also presented.In this system,a modification is made on the modified Wheatstone bridge to evaluate its performance by adding another digital multimeter to measure the ratio between the unknown and the standard resistors simultaneously.This bridge is verified by comparing the measured values of 10 kΩresistor obtained by the two methods with its actual value.The bridge accuracy is in the level of 10-6 except for the 1 kΩresistor,and the bridge asymmetry is also evaluated.It is found the asymmetry is in the level of 10-6 for the resistors from 10 kΩto 100 MΩand in the level of 10-5 for 1 kΩresistors.The introduced bridges operations are controlled by LabVIEW programs designed specially for this purpose,and the expanded uncertainty is also evaluated for all measurement results.展开更多
Current dependence and stability of the measured resistance value are very important for the accurate measurement of DC standard resistor. In this paper, the volt-ampere （V-I） measurement method has been applied ...Current dependence and stability of the measured resistance value are very important for the accurate measurement of DC standard resistor. In this paper, the volt-ampere （V-I） measurement method has been applied to study the current depend-ence of four different types of standard resistors. Diverse values are obtained through the investigation of their stability at dif-ferent currents. Therefore, the current dependence coefficient （CDC） can be determined for each one of the studied resistors. Research shows CDC depends on the applied current value, the measurement time and the resistor type, as clearly demonstra-ted in this research.展开更多
A set of seven single junction thermal converter Micropotentiometers (μPots) has been constructed at the National Institute for Standards (NIS), Egypt. This set has been built to cover the low ac voltage ranges from ...A set of seven single junction thermal converter Micropotentiometers (μPots) has been constructed at the National Institute for Standards (NIS), Egypt. This set has been built to cover the low ac voltage ranges from 2 mV to 200 mV at frequencies from 40 Hz up to 20 kHz. The construction of the μPots set has been presented and an adopted calibration method has been performed as well. This method has been performed by means of a step-down procedure using a Digital Multi-Meter (DMM). The scaling procedures have been carried out in sequential steps starting from the calibration of the 200 mV-μpot by using DMM that is accurately calibrated at its 200 mV ac voltage range down to 2 mV-μPot. Furthermore, a new automatic calibration system has been established to achieve the scaling procedures. This system has been specially designed using Laboratory Virtual Instrument Engineering Workbench (LabVIEW) software to overcome the deficiencies of manual methods. The automatic calibration has been investigated of all mPots at different frequencies. The ac-dc differences for the μPots and their uncertainty evaluation from 2 mV to 200 mV at different frequencies from 40 Hz to 20 kHz have been determined.展开更多
Metal sulfides have been widely enticed as battery-type electrodes in supercapacitor devices because of their maximal theoretical capacitance.Nevertheless,their lower conductivity and ion transport kinetics can largel...Metal sulfides have been widely enticed as battery-type electrodes in supercapacitor devices because of their maximal theoretical capacitance.Nevertheless,their lower conductivity and ion transport kinetics can largely restrict their rate performance,hence the practical usage in fields of demanding high power devices.Therefore,the design of new electrodes with higher energy and power densities remains a highly challenging task.To the best of our knowledge,a novel hierarchical composite of Al-CoS_(2) on nitrogendoped graphene(NG)is prepared based on a zeolite imidazole framework using a simple and scalable hydrothermal process.In this hybrid,ultrathin Al-CoS_(2) nanosheet arrays are vertically orientated on the NG framework to limit self-aggregation,hence increasing the electrical property and cycle stability of composite.It is investigated that the Al/Co feeding ratio plays a crucial role in controlling the obtained hierarchical structure of Al-Co-S sheets and their electrode performance.Also,Al^(3+) can influence remarkably the morphology and electrochemical property of the resultant graphene composite.An effective synergism is noticed between the redox Al-CoS_(2) and NG resulting in fast electron transfer and chargingdischarging processes.Surprisingly,when the as-developed composite is utilized as a positive electrode at an applied current density of 1 A/g,a specific capacitance of 1915.8 F/g is attained with ultra-long cycle stability(96%,10,000 cycles)and an excellent retention rate(~89%).As a consequence,when a solid-state asymmetric supercapacitor(ASC)device is made by combining an Al-CoS_(2) @NG hybrid with a negative electrode made of polyaniline(PANI)derived carbon nanorods(PCNRs),it demonstrates remarkable specific capacitance(188 F/g),energy density(66.9 Wh/kg),and cyclic stability of 92%after 10,000 cycles.This may open the pathway for the application of the next-generation supercapacitors in the future.展开更多
Conversion of rice straw (RS) as one of agricultural plant wastes (about 45% of the volume of rice production) to valuable industrial product was achieved, by grafting different amounts of dimethylaminoethyl methacryl...Conversion of rice straw (RS) as one of agricultural plant wastes (about 45% of the volume of rice production) to valuable industrial product was achieved, by grafting different amounts of dimethylaminoethyl methacrylate (DMAEM) on it using potassium permanganate/nitric acid redox system. This was done to obtain six levels of poly (DMAEM)—rice straw graft copolymers (PDMAEMRS) having different graft yields (expressed as N%) with increasing order and designated as (PDMAEMRS 1 to PDMAEMRS 6). The latter copolymers were dispersed in aqueous solution of heavy metal ions Cu (II) ions and filtered to form rice straw co-polymer—metal ions complex. Different factors affecting the heavy metal ions removal such as pH, extent of grafting, treatment time and rice straw dose were studied in detail. It was found from the obtained results that;the residual metal ions removal from their aqueous solutions increased with 1) increasing the extent of grafting of PDMAEMRS i.e. from PDMAEMRS 1 to PDMAEMRS 6;2) increasing the pH of the metal ions solution complex from 1 to 8;3) increasing the rice straw dosage from 0.50 to 2.0 g, then leveled off thereafter;4) increasing the time of the reaction up to 20 minute then leveled off after that. On the other hand, Pb (II), Cd (II) and Hg (II) ions were also removed from their solutions with different extent. Furthermore, the prepared co-polymer could be recovered by washing the metal ions from the complex with weak acid 1 N HNO3 (pH 2) and the metal-binding activity of the rice straw was slightly reduced by this process. Finally, the ability of PDMAEMRS to remove three types of acid dyes from their solutions was also reported.展开更多
It is necessary to achieve the best specifications in carpets that provide safety to human health in establishments and buildings. This can be achieved by reducing the emissions of toxic gases from combustion via cont...It is necessary to achieve the best specifications in carpets that provide safety to human health in establishments and buildings. This can be achieved by reducing the emissions of toxic gases from combustion via controlling the carpets composition. This research presents a study on carpets behavior when burning samples with different mixing specifications to determine the combustion products by conducting a test using cone Calorimeter to determine the effect of different structures of the carpet on combustion products. The study includes the effect of both the quality of the material used and their different densities and thicknesses. The research provides an analysis of carpet combustion products from different emissions, such as the amount of carbon monoxide CO, the amount of carbon dioxide CO2, smoke density, heat of combustion, and the heat released rate. It is clear that the rate of heat released is uneven in samples with different percentages of mixing. The samples with higher mixing percentage of synthetic fibers give lower temperature while the samples with higher wool percentage give higher temperature. The temperature of combustion increases gradually with the increase of the percentage of wool while the density of the smoke decreases which achieves the required safety of carpets. In addition to this, the research proves the increase of both CO and CO2 as the percentage of synthetic fibers in products which confirms the necessity to avoid the adverse effects of these emissions on human health.展开更多
Two new miniature metallic sealed-cells containing the triple point of water, WTP （273.16 K） and the triple point of mercury, HgTP （234.3156 K） have been constructed for the realization of the International Temper...Two new miniature metallic sealed-cells containing the triple point of water, WTP （273.16 K） and the triple point of mercury, HgTP （234.3156 K） have been constructed for the realization of the International Temperature Scale of 1990 （ITS-90） at the National Institute of Standards （NIS-Egypt）. The two new cells, in addition to a previously realized argon and oxygen triple point cells, will provide facilities for the calibration of capsule-type standard platinum resistance thermometers （CSPRTs） at one single run. Many phase transition plateaux were carried out and compared to the laboratory large reference cells using the same thermometers in order to test the performance of the new cell.展开更多
Background: Radiotherapy (RT) techniques after Conservative Breast Surgery (CBS) vary. Three Dimension (3D) planning allows for better plan optimization compared to 2 Dimension (2D) plans and also allowing for creatin...Background: Radiotherapy (RT) techniques after Conservative Breast Surgery (CBS) vary. Three Dimension (3D) planning allows for better plan optimization compared to 2 Dimension (2D) plans and also allowing for creating Dose Volume Histograms (DVHs) for both Planning Target Volume (PTV) and Organs at Risk (OAR). Patients and Methods: Twenty consecutive patients with CBS planned for whole breast and supraclavicular (SCV) RT at the National Cancer Institute (NCI), Egypt between January and June 2016 were included in this study. All patients were planned clinically in 2D fashion with no more than 2 cm of ipsilateral lung allowed in the tangential fields “Limited 2D” (Limit-2D) then Target and OAR volumes were drawn according to the Radiation Therapy Oncology Group (RTOG) guidelines and 3D plans and a central slice PTV-based 2D plan, “Modified 2D” (Mod-2D), were performed in the same Computerized Tomography (CT) slices for each patient. Mono-Iso-Centeric technique (MIT) was used in 3D plans. DVH parameters were used to compare the three plans. Results: In 3D plans, compared to Limit-2D, coverage improved for the intact breast (V95% = 95% versus (Vs) 69%, p = 0.036) and SCVPTV (V90% = 90% Vs 65%, p = 0.01). The breast and SCV V 107%, V112% and Dmax were better with 3D plan however not statistical significant (NS). Junctional hot spots were 120% and 107% in the Limit-2D and 3D plans respectively (p = 0.04). The dose to the heart, mean (333 Vs 491 cGy), V10 (5% Vs 10%) and V20 (3% Vs 7%), Ipsilateral lung V20 (19% Vs 26%), and contra lateral breast D-max (205 Vs 462 cGy) were higher in 3D plans however NS, and the dose to the cord was the same. Comparison between 3D and Mod-2D showed better OAR sparing with 3D with mean heart dose (491 cGy Vs 782 cGy, p = 0.025) and Ipsilateral lung V20 (26% Vs 32%, p = 0.07% with statistically comparable target coverage. Conclusion: This study demonstrated that application of 3D plan using MIT improves coverage of breast and SCVPTVs with minimizing hot spot at the junctional area if compared with Limit-2D plans with comparable dose to OAR. When compared with Mod-2D plans, 3D plans not only had better target coverage but also better sparing of OAR, the latter was statistically significant.展开更多
The present work aims at studying the effect of Ultra-Violet/Ozone (UV/O3) irradiation of cotton fabrics on their interaction with chitosan/citric acid based formulation and, the onset of this on the ability of treate...The present work aims at studying the effect of Ultra-Violet/Ozone (UV/O3) irradiation of cotton fabrics on their interaction with chitosan/citric acid based formulation and, the onset of this on the ability of treated fabrics to remove heavy metal ions from their aqueous solutions. To achieve the goal, the cotton fabrics were preirradiated for 90 minutes using UV/O3 as radiation source. The irradiated and the unirrdadiated cotton fabrics were submitted to finishing formulation consisting essentially of chitosan as a finishing agent and citric acid as crosslinking agent in combination with sodium hypophosphite (SHP) as a catalyst. Finishing formulation containing different concentrations of chitosan (0 - 4) along with citric acid (8 g/l) and SHP (4 g/l) were used and the interaction of chitosan with the cotton fabric was assessed through nitrogen measurement. The preirradiated and chemically finished fabrics vis-à-vis the unirrdadiated fabrics were examined for metal ion removal. Results conclude that the preirradiated cotton fabrics exhibit higher nitrogen content than the unirrdadiated fabrics. The same holds true for heavy metal removal, exemplified by Zn2+ and Cd2+ ions from their aqueous solutions. That is, preirradiated fabrics containing chitosan display higher percent heavy metal removal than their unirrdadiated mates.展开更多
In the present work, composites of poly (methyl methacrylate)/titanium oxide nanoparticles (100/0, 97.5/2.5, 95/5, 92.5/7.5, 90/10 and 0/100 wt/wt%)were prepared to be used as bioequivalent materials according to thei...In the present work, composites of poly (methyl methacrylate)/titanium oxide nanoparticles (100/0, 97.5/2.5, 95/5, 92.5/7.5, 90/10 and 0/100 wt/wt%)were prepared to be used as bioequivalent materials according to their importance broad practical and medical applications. Thermal properties as well as X-ray diffraction analyses were employed to characterize the structure properties of such composite. The obtained results showed variations in the glass transition temperature (Tg), the melting temperature (Tm), shape and area of thermal peaks which were attributed to the different degrees of crystallinity and the existence of interactions between PMMA and TiO2 nanoparticle molecules. The XRD patterns showed sharpening of peaks at different concentrations of nano-TiO2 powder with PMMA. This indicated changes in the crystallinity/amorphosity ratio, and also suggested that the miscibility between the amorphous components of homo- polymers PMMA and nano-TiO2 powder is possible.The results showed that nano-TiO2 powder mix with PMMA can improve the thermal stability of the homo-polymer under investigation, lead- ing to interesting technological applications.展开更多
Automation in measurement has wide range of electrical metrology applications and construction of powerful calibration software is one of the highly accurate metrological laboratories’ priorities. Thus, two automatic...Automation in measurement has wide range of electrical metrology applications and construction of powerful calibration software is one of the highly accurate metrological laboratories’ priorities. Thus, two automatic systems for controlling and calibrating the electrical reference standards have been established at National Institute for Standards (NIS), Egypt. The first system has been built to calibrate the zener diode reference standards while the second one has been built to calibrate the electrical sourcing and measuring instruments. These two systems act as the comprehensive and reliable structure that, from the national electrical standards, disseminates the traceability to all the electrical units under calibration. The software of the two systems has been built using the Laboratory Virtual Instrument Engineering Workbench (LabVIEW) graphical language. The standard development procedures have been followed in the building of both systems software. The software requirement specifications as well as functional specifications are taken into consideration. Design, implementation and testing of the software have been performed. Furthermore, software validation for measurements’ uncertainty as well as results’ compatibility in both automatic and manual modes has been achieved.展开更多
Holography is an interesting tool in creating real objects and scenes which can be projected anywhere with accurate details and depth impression. It is also found to be more attractive to the artists than other altern...Holography is an interesting tool in creating real objects and scenes which can be projected anywhere with accurate details and depth impression. It is also found to be more attractive to the artists than other alternatives. For that reason, digital holography is being used as a display technology in cartoon movies. Since this application is dependent on the performance and the simplicity of the available display technology, it becomes very useful to improve the display technique in order to become fast, simple, and attractive by being combined with computer graphical effects. This paper discusses a simulation of a digital holographic model as a three dimensional (3D) display system and its application in making cartoon holography.展开更多
The concentrations of 20 trace elements in several ceramics tiles and ceramic composites used in Egypt were elementally analyzed by neutron activation analysis(NAA) technique. The samples and standard were irradiate...The concentrations of 20 trace elements in several ceramics tiles and ceramic composites used in Egypt were elementally analyzed by neutron activation analysis(NAA) technique. The samples and standard were irradiated with reactor for 4 h(in the Second Research Egyptian Reactor(Et-RR-2)) with thermal neutron flux 5.9×10 13 n/(cm 2·s).The gamma-ray spectra obtained were measured for several times by means of the hyper pure germanium detection system(HPGe). Also a solid state nuclear track detector(SSNTD) CR-39, was used to measure the emanation rate of radon for these samples. The radium concentrations were found to vary from 0.39—3.59 ppm and the emanation rates were found to vary from (0.728—5.688) × 10 -4 kg/(m 2· s).The elemental analysis of the ceramic tiles and ceramic composites have a great importance in assigning the physical properties and in turn the quality of the material.展开更多
Ultraviolet-visible（UV-Vis）spectrophotometry is commonly used in analytical laboratories for qualitative and quantitative analyses.To make the data obtained reliable,an experimental instrument must be calibrated.Nat...Ultraviolet-visible（UV-Vis）spectrophotometry is commonly used in analytical laboratories for qualitative and quantitative analyses.To make the data obtained reliable,an experimental instrument must be calibrated.National Institute for Standards（NIS）in Egypt builds up aphotometric method to ensure the competence of absorbance and transmittance to the standard international and national requirements.This paper presents an instrument for UV-Vis measurement,discusses the factors affecting measurement reliability and estabishes the uncertainty model including correspoding measurement parameters.展开更多
Phototherapy lamps are the most effective and safest in the treatment of several medical treatments such as bilirubin. They transfer radiant energy expressed by irradiance unit in W/m2 into the skin specifically to ac...Phototherapy lamps are the most effective and safest in the treatment of several medical treatments such as bilirubin. They transfer radiant energy expressed by irradiance unit in W/m2 into the skin specifically to achieve a therapeutic reduction in the bilirubin concentration in the blood. National Institute for Standards （NIS） in Egypt builds up a radiometric method to en- sure the competence of phototherapy sources （luminaire） to the standard international and national requirements. Hence, NIS provides traceability to customer through unbroken chain of phototherapy radiometer calibrated as irradiance response in W/m2. Uncertainty model including all parameters accompanied with the measurements is studied.展开更多
AC currents are automatically calibrated by two different thermal current converter(TCC)designs.The two designs are different in the used number of the thermal-elements(TEs).Consequently they differ in their output el...AC currents are automatically calibrated by two different thermal current converter(TCC)designs.The two designs are different in the used number of the thermal-elements(TEs).Consequently they differ in their output electro motive force(EMF).Studying the effect of changing the output EMF is done in this paper through calibrating AC currents.5 mA and 5 A are accurately calibrated at different frequencies 55 Hz,1 kHz and10 kHz by the two TCCs.A comparison is made between the results to evaluate the effect of the output EMF value on the accuracy and the uncertainty of the low and higher AC current calibration.A LabVIEW program is designed for this accurate automatic calibration to overcome the problems of the manual calibration on the thermal converters.展开更多
Form error measurement is a critical exercise in providing measures for the quality control in the precision manufacturing industry.Coordinate measuring machine （CMM） is one of the automated systems used in the accu...Form error measurement is a critical exercise in providing measures for the quality control in the precision manufacturing industry.Coordinate measuring machine （CMM） is one of the automated systems used in the accurate and precise dimensional measurements and geometrical form.This paper aims to study the effect of dynamic original unforeseeable errors at different undulations per revolution （UPR） of standard artifact measurement using selected two types of CMM touchtriggering stylus.Stylus-type and stylus-speed parameters were adopted and utilized throughout the course of experiment.The results are analyzed using fast Fourier transformation to obtain foreseeable geometrical errors due to CMM machine structure and stylus scanning speeds.The results of experiment successfully indicate that the number of UPR plays an important role in determining the CMM accuracy level of the roundness measurement result.Some specific error equations for stylus system and machine structure responses have been postulated and analysed to empirically predict the accuracy of PRISMOBridge-CMM-type at National Institute for Standards （NIS） in egypt.展开更多
The ambient dose of radiation therapy and nuclear medicine units of Clinical Oncology Hospital, Menoufia University were investigated using thermoluminescence dosimeter MTS-700 and surveymeter (Inspector Radiation Ale...The ambient dose of radiation therapy and nuclear medicine units of Clinical Oncology Hospital, Menoufia University were investigated using thermoluminescence dosimeter MTS-700 and surveymeter (Inspector Radiation Alert). The maximum% difference between read out of both MTS-700 (TLD) and surveymeter did not exceed 6% and 8% for the two hospital units respectively. Values of the annual ambient dose received in both hospital units were found to be incompliant with radiation protection regulations. In addition, the extremity effective dose Hp (0.07) of staff in nuclear medicine unit was measured using wrist and finger techniques. Results indicate in-homogenies distribution of fingertips doses. Radiation doses received by the wrists and fingertips of radiopharmaceutical staff preparing 99mTc syringe were observed to be higher by a factor of about 1.41 and 1.44 respectively than those for the administrating staff whom injecting patients by 99mTc syringe, but also still in congruent with international radiation protection regulations.展开更多
This paper study stability of saturated salt solutions cells at 25 ℃. These cells were prepared and measured at National Institute for Standard （NIS-Egypt） to study the stability of the saturated salt solutions. Th...This paper study stability of saturated salt solutions cells at 25 ℃. These cells were prepared and measured at National Institute for Standard （NIS-Egypt） to study the stability of the saturated salt solutions. The study was carried out using three saturated salt solutions, which are Potassium Acetate 22.5%, Potassium Iodide 68.9% and Potassium Sulphate 97.3% to cover low, medium and high relative humidity. The study was carried out using different shapes and volumes half liter spherical, liter spherical and liter conical per each salt which was prepared. The apparatus which used in measurement system in the first time are the same which used after ten years. The results show that the change of relative humidity value after ten years ranged from 0.1% to 0.7%. This value is suitable within uncertainty ＋ 2%. The period of stability for each run for all cells was found to be more than five hours and this period enough for calibration. The measurements show that the cells are stable for more than ten years with accepted value.展开更多
The performance of many optical glass elements depends on the structure of the surface. The high refractive index of flint glass is advantageous in constructing some optical elements (lenses, prisms, beam splitters, ...The performance of many optical glass elements depends on the structure of the surface. The high refractive index of flint glass is advantageous in constructing some optical elements (lenses, prisms, beam splitters, …). Also, high achromaticity and size reduction in oblique incidence TIR (total internal reflection) phase retarders require high-index glass. The present work is interested in studying the optical properties of the thin surface layer formed on TIR rhomb retarder at different wavelengths to indicate the extent to which this surface layer affects the performance of this TIR rhomb retarder and show how to overcome this effect.展开更多
文摘A new system for measuring low-ohmic standard resistors through a dual current sources bridge is introduced.It is used for low resistance measurements from 1 mΩto 1Ωat 1∶1 ratio,which is suitable for the laboratories without cryogenic current comparators(CCC)or direct current comparators(DCC)bridges.Behavior of this bridge is evaluated by comparing its measured values with the unknown resistor values obtained by another method.The accuracy of the introduced bridge is in the level of 10-5 for the 1 mΩresistor,and in the level of 10-4 for the 10 mΩ,100 mΩand 1Ωresistors.Moreover,a dual voltage sources system for the measurement of DC standard resistors from 1 kΩto 100 MΩis also presented.In this system,a modification is made on the modified Wheatstone bridge to evaluate its performance by adding another digital multimeter to measure the ratio between the unknown and the standard resistors simultaneously.This bridge is verified by comparing the measured values of 10 kΩresistor obtained by the two methods with its actual value.The bridge accuracy is in the level of 10-6 except for the 1 kΩresistor,and the bridge asymmetry is also evaluated.It is found the asymmetry is in the level of 10-6 for the resistors from 10 kΩto 100 MΩand in the level of 10-5 for 1 kΩresistors.The introduced bridges operations are controlled by LabVIEW programs designed specially for this purpose,and the expanded uncertainty is also evaluated for all measurement results.
文摘Current dependence and stability of the measured resistance value are very important for the accurate measurement of DC standard resistor. In this paper, the volt-ampere （V-I） measurement method has been applied to study the current depend-ence of four different types of standard resistors. Diverse values are obtained through the investigation of their stability at dif-ferent currents. Therefore, the current dependence coefficient （CDC） can be determined for each one of the studied resistors. Research shows CDC depends on the applied current value, the measurement time and the resistor type, as clearly demonstra-ted in this research.
文摘A set of seven single junction thermal converter Micropotentiometers (μPots) has been constructed at the National Institute for Standards (NIS), Egypt. This set has been built to cover the low ac voltage ranges from 2 mV to 200 mV at frequencies from 40 Hz up to 20 kHz. The construction of the μPots set has been presented and an adopted calibration method has been performed as well. This method has been performed by means of a step-down procedure using a Digital Multi-Meter (DMM). The scaling procedures have been carried out in sequential steps starting from the calibration of the 200 mV-μpot by using DMM that is accurately calibrated at its 200 mV ac voltage range down to 2 mV-μPot. Furthermore, a new automatic calibration system has been established to achieve the scaling procedures. This system has been specially designed using Laboratory Virtual Instrument Engineering Workbench (LabVIEW) software to overcome the deficiencies of manual methods. The automatic calibration has been investigated of all mPots at different frequencies. The ac-dc differences for the μPots and their uncertainty evaluation from 2 mV to 200 mV at different frequencies from 40 Hz to 20 kHz have been determined.
基金supported by the National Research Foundation of Korea(NRF)funded by the Ministry of Education(NRF-2019R1l1A3A010638331,NRF-2021R1I1A1A01059870 and NRF-2022R1I1A1A01069960)the Hannam University research fund in 2022+4 种基金the Marie Sklodowska-Curie grant agreement(801538)the CONEX-Plus program at the Universidad CarlosⅢde Madridthe European Union’s Horizon 2020 research and innovation programmeAbdolkhaled Mohammadi(Universitéde Montpellier,France)Pranay Barkataki(Sony R&D,India)for fruitful discussion and support。
文摘Metal sulfides have been widely enticed as battery-type electrodes in supercapacitor devices because of their maximal theoretical capacitance.Nevertheless,their lower conductivity and ion transport kinetics can largely restrict their rate performance,hence the practical usage in fields of demanding high power devices.Therefore,the design of new electrodes with higher energy and power densities remains a highly challenging task.To the best of our knowledge,a novel hierarchical composite of Al-CoS_(2) on nitrogendoped graphene(NG)is prepared based on a zeolite imidazole framework using a simple and scalable hydrothermal process.In this hybrid,ultrathin Al-CoS_(2) nanosheet arrays are vertically orientated on the NG framework to limit self-aggregation,hence increasing the electrical property and cycle stability of composite.It is investigated that the Al/Co feeding ratio plays a crucial role in controlling the obtained hierarchical structure of Al-Co-S sheets and their electrode performance.Also,Al^(3+) can influence remarkably the morphology and electrochemical property of the resultant graphene composite.An effective synergism is noticed between the redox Al-CoS_(2) and NG resulting in fast electron transfer and chargingdischarging processes.Surprisingly,when the as-developed composite is utilized as a positive electrode at an applied current density of 1 A/g,a specific capacitance of 1915.8 F/g is attained with ultra-long cycle stability(96%,10,000 cycles)and an excellent retention rate(~89%).As a consequence,when a solid-state asymmetric supercapacitor(ASC)device is made by combining an Al-CoS_(2) @NG hybrid with a negative electrode made of polyaniline(PANI)derived carbon nanorods(PCNRs),it demonstrates remarkable specific capacitance(188 F/g),energy density(66.9 Wh/kg),and cyclic stability of 92%after 10,000 cycles.This may open the pathway for the application of the next-generation supercapacitors in the future.
文摘Conversion of rice straw (RS) as one of agricultural plant wastes (about 45% of the volume of rice production) to valuable industrial product was achieved, by grafting different amounts of dimethylaminoethyl methacrylate (DMAEM) on it using potassium permanganate/nitric acid redox system. This was done to obtain six levels of poly (DMAEM)—rice straw graft copolymers (PDMAEMRS) having different graft yields (expressed as N%) with increasing order and designated as (PDMAEMRS 1 to PDMAEMRS 6). The latter copolymers were dispersed in aqueous solution of heavy metal ions Cu (II) ions and filtered to form rice straw co-polymer—metal ions complex. Different factors affecting the heavy metal ions removal such as pH, extent of grafting, treatment time and rice straw dose were studied in detail. It was found from the obtained results that;the residual metal ions removal from their aqueous solutions increased with 1) increasing the extent of grafting of PDMAEMRS i.e. from PDMAEMRS 1 to PDMAEMRS 6;2) increasing the pH of the metal ions solution complex from 1 to 8;3) increasing the rice straw dosage from 0.50 to 2.0 g, then leveled off thereafter;4) increasing the time of the reaction up to 20 minute then leveled off after that. On the other hand, Pb (II), Cd (II) and Hg (II) ions were also removed from their solutions with different extent. Furthermore, the prepared co-polymer could be recovered by washing the metal ions from the complex with weak acid 1 N HNO3 (pH 2) and the metal-binding activity of the rice straw was slightly reduced by this process. Finally, the ability of PDMAEMRS to remove three types of acid dyes from their solutions was also reported.
文摘It is necessary to achieve the best specifications in carpets that provide safety to human health in establishments and buildings. This can be achieved by reducing the emissions of toxic gases from combustion via controlling the carpets composition. This research presents a study on carpets behavior when burning samples with different mixing specifications to determine the combustion products by conducting a test using cone Calorimeter to determine the effect of different structures of the carpet on combustion products. The study includes the effect of both the quality of the material used and their different densities and thicknesses. The research provides an analysis of carpet combustion products from different emissions, such as the amount of carbon monoxide CO, the amount of carbon dioxide CO2, smoke density, heat of combustion, and the heat released rate. It is clear that the rate of heat released is uneven in samples with different percentages of mixing. The samples with higher mixing percentage of synthetic fibers give lower temperature while the samples with higher wool percentage give higher temperature. The temperature of combustion increases gradually with the increase of the percentage of wool while the density of the smoke decreases which achieves the required safety of carpets. In addition to this, the research proves the increase of both CO and CO2 as the percentage of synthetic fibers in products which confirms the necessity to avoid the adverse effects of these emissions on human health.
文摘Two new miniature metallic sealed-cells containing the triple point of water, WTP （273.16 K） and the triple point of mercury, HgTP （234.3156 K） have been constructed for the realization of the International Temperature Scale of 1990 （ITS-90） at the National Institute of Standards （NIS-Egypt）. The two new cells, in addition to a previously realized argon and oxygen triple point cells, will provide facilities for the calibration of capsule-type standard platinum resistance thermometers （CSPRTs） at one single run. Many phase transition plateaux were carried out and compared to the laboratory large reference cells using the same thermometers in order to test the performance of the new cell.
文摘Background: Radiotherapy (RT) techniques after Conservative Breast Surgery (CBS) vary. Three Dimension (3D) planning allows for better plan optimization compared to 2 Dimension (2D) plans and also allowing for creating Dose Volume Histograms (DVHs) for both Planning Target Volume (PTV) and Organs at Risk (OAR). Patients and Methods: Twenty consecutive patients with CBS planned for whole breast and supraclavicular (SCV) RT at the National Cancer Institute (NCI), Egypt between January and June 2016 were included in this study. All patients were planned clinically in 2D fashion with no more than 2 cm of ipsilateral lung allowed in the tangential fields “Limited 2D” (Limit-2D) then Target and OAR volumes were drawn according to the Radiation Therapy Oncology Group (RTOG) guidelines and 3D plans and a central slice PTV-based 2D plan, “Modified 2D” (Mod-2D), were performed in the same Computerized Tomography (CT) slices for each patient. Mono-Iso-Centeric technique (MIT) was used in 3D plans. DVH parameters were used to compare the three plans. Results: In 3D plans, compared to Limit-2D, coverage improved for the intact breast (V95% = 95% versus (Vs) 69%, p = 0.036) and SCVPTV (V90% = 90% Vs 65%, p = 0.01). The breast and SCV V 107%, V112% and Dmax were better with 3D plan however not statistical significant (NS). Junctional hot spots were 120% and 107% in the Limit-2D and 3D plans respectively (p = 0.04). The dose to the heart, mean (333 Vs 491 cGy), V10 (5% Vs 10%) and V20 (3% Vs 7%), Ipsilateral lung V20 (19% Vs 26%), and contra lateral breast D-max (205 Vs 462 cGy) were higher in 3D plans however NS, and the dose to the cord was the same. Comparison between 3D and Mod-2D showed better OAR sparing with 3D with mean heart dose (491 cGy Vs 782 cGy, p = 0.025) and Ipsilateral lung V20 (26% Vs 32%, p = 0.07% with statistically comparable target coverage. Conclusion: This study demonstrated that application of 3D plan using MIT improves coverage of breast and SCVPTVs with minimizing hot spot at the junctional area if compared with Limit-2D plans with comparable dose to OAR. When compared with Mod-2D plans, 3D plans not only had better target coverage but also better sparing of OAR, the latter was statistically significant.
文摘The present work aims at studying the effect of Ultra-Violet/Ozone (UV/O3) irradiation of cotton fabrics on their interaction with chitosan/citric acid based formulation and, the onset of this on the ability of treated fabrics to remove heavy metal ions from their aqueous solutions. To achieve the goal, the cotton fabrics were preirradiated for 90 minutes using UV/O3 as radiation source. The irradiated and the unirrdadiated cotton fabrics were submitted to finishing formulation consisting essentially of chitosan as a finishing agent and citric acid as crosslinking agent in combination with sodium hypophosphite (SHP) as a catalyst. Finishing formulation containing different concentrations of chitosan (0 - 4) along with citric acid (8 g/l) and SHP (4 g/l) were used and the interaction of chitosan with the cotton fabric was assessed through nitrogen measurement. The preirradiated and chemically finished fabrics vis-à-vis the unirrdadiated fabrics were examined for metal ion removal. Results conclude that the preirradiated cotton fabrics exhibit higher nitrogen content than the unirrdadiated fabrics. The same holds true for heavy metal removal, exemplified by Zn2+ and Cd2+ ions from their aqueous solutions. That is, preirradiated fabrics containing chitosan display higher percent heavy metal removal than their unirrdadiated mates.
文摘In the present work, composites of poly (methyl methacrylate)/titanium oxide nanoparticles (100/0, 97.5/2.5, 95/5, 92.5/7.5, 90/10 and 0/100 wt/wt%)were prepared to be used as bioequivalent materials according to their importance broad practical and medical applications. Thermal properties as well as X-ray diffraction analyses were employed to characterize the structure properties of such composite. The obtained results showed variations in the glass transition temperature (Tg), the melting temperature (Tm), shape and area of thermal peaks which were attributed to the different degrees of crystallinity and the existence of interactions between PMMA and TiO2 nanoparticle molecules. The XRD patterns showed sharpening of peaks at different concentrations of nano-TiO2 powder with PMMA. This indicated changes in the crystallinity/amorphosity ratio, and also suggested that the miscibility between the amorphous components of homo- polymers PMMA and nano-TiO2 powder is possible.The results showed that nano-TiO2 powder mix with PMMA can improve the thermal stability of the homo-polymer under investigation, lead- ing to interesting technological applications.
文摘Automation in measurement has wide range of electrical metrology applications and construction of powerful calibration software is one of the highly accurate metrological laboratories’ priorities. Thus, two automatic systems for controlling and calibrating the electrical reference standards have been established at National Institute for Standards (NIS), Egypt. The first system has been built to calibrate the zener diode reference standards while the second one has been built to calibrate the electrical sourcing and measuring instruments. These two systems act as the comprehensive and reliable structure that, from the national electrical standards, disseminates the traceability to all the electrical units under calibration. The software of the two systems has been built using the Laboratory Virtual Instrument Engineering Workbench (LabVIEW) graphical language. The standard development procedures have been followed in the building of both systems software. The software requirement specifications as well as functional specifications are taken into consideration. Design, implementation and testing of the software have been performed. Furthermore, software validation for measurements’ uncertainty as well as results’ compatibility in both automatic and manual modes has been achieved.
文摘Holography is an interesting tool in creating real objects and scenes which can be projected anywhere with accurate details and depth impression. It is also found to be more attractive to the artists than other alternatives. For that reason, digital holography is being used as a display technology in cartoon movies. Since this application is dependent on the performance and the simplicity of the available display technology, it becomes very useful to improve the display technique in order to become fast, simple, and attractive by being combined with computer graphical effects. This paper discusses a simulation of a digital holographic model as a three dimensional (3D) display system and its application in making cartoon holography.
文摘The concentrations of 20 trace elements in several ceramics tiles and ceramic composites used in Egypt were elementally analyzed by neutron activation analysis(NAA) technique. The samples and standard were irradiated with reactor for 4 h(in the Second Research Egyptian Reactor(Et-RR-2)) with thermal neutron flux 5.9×10 13 n/(cm 2·s).The gamma-ray spectra obtained were measured for several times by means of the hyper pure germanium detection system(HPGe). Also a solid state nuclear track detector(SSNTD) CR-39, was used to measure the emanation rate of radon for these samples. The radium concentrations were found to vary from 0.39—3.59 ppm and the emanation rates were found to vary from (0.728—5.688) × 10 -4 kg/(m 2· s).The elemental analysis of the ceramic tiles and ceramic composites have a great importance in assigning the physical properties and in turn the quality of the material.
文摘Ultraviolet-visible（UV-Vis）spectrophotometry is commonly used in analytical laboratories for qualitative and quantitative analyses.To make the data obtained reliable,an experimental instrument must be calibrated.National Institute for Standards（NIS）in Egypt builds up aphotometric method to ensure the competence of absorbance and transmittance to the standard international and national requirements.This paper presents an instrument for UV-Vis measurement,discusses the factors affecting measurement reliability and estabishes the uncertainty model including correspoding measurement parameters.
文摘Phototherapy lamps are the most effective and safest in the treatment of several medical treatments such as bilirubin. They transfer radiant energy expressed by irradiance unit in W/m2 into the skin specifically to achieve a therapeutic reduction in the bilirubin concentration in the blood. National Institute for Standards （NIS） in Egypt builds up a radiometric method to en- sure the competence of phototherapy sources （luminaire） to the standard international and national requirements. Hence, NIS provides traceability to customer through unbroken chain of phototherapy radiometer calibrated as irradiance response in W/m2. Uncertainty model including all parameters accompanied with the measurements is studied.
文摘AC currents are automatically calibrated by two different thermal current converter(TCC)designs.The two designs are different in the used number of the thermal-elements(TEs).Consequently they differ in their output electro motive force(EMF).Studying the effect of changing the output EMF is done in this paper through calibrating AC currents.5 mA and 5 A are accurately calibrated at different frequencies 55 Hz,1 kHz and10 kHz by the two TCCs.A comparison is made between the results to evaluate the effect of the output EMF value on the accuracy and the uncertainty of the low and higher AC current calibration.A LabVIEW program is designed for this accurate automatic calibration to overcome the problems of the manual calibration on the thermal converters.
文摘Form error measurement is a critical exercise in providing measures for the quality control in the precision manufacturing industry.Coordinate measuring machine （CMM） is one of the automated systems used in the accurate and precise dimensional measurements and geometrical form.This paper aims to study the effect of dynamic original unforeseeable errors at different undulations per revolution （UPR） of standard artifact measurement using selected two types of CMM touchtriggering stylus.Stylus-type and stylus-speed parameters were adopted and utilized throughout the course of experiment.The results are analyzed using fast Fourier transformation to obtain foreseeable geometrical errors due to CMM machine structure and stylus scanning speeds.The results of experiment successfully indicate that the number of UPR plays an important role in determining the CMM accuracy level of the roundness measurement result.Some specific error equations for stylus system and machine structure responses have been postulated and analysed to empirically predict the accuracy of PRISMOBridge-CMM-type at National Institute for Standards （NIS） in egypt.
文摘The ambient dose of radiation therapy and nuclear medicine units of Clinical Oncology Hospital, Menoufia University were investigated using thermoluminescence dosimeter MTS-700 and surveymeter (Inspector Radiation Alert). The maximum% difference between read out of both MTS-700 (TLD) and surveymeter did not exceed 6% and 8% for the two hospital units respectively. Values of the annual ambient dose received in both hospital units were found to be incompliant with radiation protection regulations. In addition, the extremity effective dose Hp (0.07) of staff in nuclear medicine unit was measured using wrist and finger techniques. Results indicate in-homogenies distribution of fingertips doses. Radiation doses received by the wrists and fingertips of radiopharmaceutical staff preparing 99mTc syringe were observed to be higher by a factor of about 1.41 and 1.44 respectively than those for the administrating staff whom injecting patients by 99mTc syringe, but also still in congruent with international radiation protection regulations.
文摘This paper study stability of saturated salt solutions cells at 25 ℃. These cells were prepared and measured at National Institute for Standard （NIS-Egypt） to study the stability of the saturated salt solutions. The study was carried out using three saturated salt solutions, which are Potassium Acetate 22.5%, Potassium Iodide 68.9% and Potassium Sulphate 97.3% to cover low, medium and high relative humidity. The study was carried out using different shapes and volumes half liter spherical, liter spherical and liter conical per each salt which was prepared. The apparatus which used in measurement system in the first time are the same which used after ten years. The results show that the change of relative humidity value after ten years ranged from 0.1% to 0.7%. This value is suitable within uncertainty ＋ 2%. The period of stability for each run for all cells was found to be more than five hours and this period enough for calibration. The measurements show that the cells are stable for more than ten years with accepted value.
文摘The performance of many optical glass elements depends on the structure of the surface. The high refractive index of flint glass is advantageous in constructing some optical elements (lenses, prisms, beam splitters, …). Also, high achromaticity and size reduction in oblique incidence TIR (total internal reflection) phase retarders require high-index glass. The present work is interested in studying the optical properties of the thin surface layer formed on TIR rhomb retarder at different wavelengths to indicate the extent to which this surface layer affects the performance of this TIR rhomb retarder and show how to overcome this effect.
