Applying the extreme low-level γ-ray spectroscopic analysis the environmental neutron flux is measured using different moderator construction and environment through the reaction 197Au (n, γ) 198Au. The contribution...Applying the extreme low-level γ-ray spectroscopic analysis the environmental neutron flux is measured using different moderator construction and environment through the reaction 197Au (n, γ) 198Au. The contribution of thermal and resonance neutrons is separated using the cadmium difference technique, while fast neutrons are measured by the paraffin moderator. The results of altitude dependence of the neutron flux are discussed. The thermal neutron flux near the surface of sea water is less than its value at 100 cm over ground near sea water, while the value over the surfaces of fresh water is higher than that near the surface of sea water. Also the thermal neutron flux at 5 cm soil depth increases, then decreases to its original value at 10 cm depth and still constant until 25 cm, then decreases rapidly to reach 27% of its original value at 60 cm depth. The soil compositions, corresponding neutron temperatures and effective absorption cross sections of earth are the most effective factors on the equilibrium region of thermal neutrons in the ground.展开更多
The aim of the present study was to design and evaluate single pulse and floating double pulse valsartan core-in-cup tablets.Core tablets were prepared by direct compression of a homogenous mixture of valsartan,Avice...The aim of the present study was to design and evaluate single pulse and floating double pulse valsartan core-in-cup tablets.Core tablets were prepared by direct compression of a homogenous mixture of valsartan,Avicel PH-101,Croscarmellose sodium(CCNa),magnesium stearate&Aerosil.Weight variation,Hardness and Disintegration time were measured for the core tablets.Core-in-cup tablets were formulated using different polymers as a plug layer,including sodium alginate(SA),sodium carboxymethylcellulose(NaCMC)and hydroxypropyl methyl cellulose(HPMC).The floating behavior,water uptake and drug release from the prepared formulations were evaluated.Differential Scanning Calorimetry(DSC)was also performed to detect the possible drug excipient interaction.Stability study of the selected formula was performed at 25C&60%RH and at 40C&75%RH for 3 months.Finally,the existence of the selected formula in the stomach after oral administration to human volunteers was verified via x-ray radiography.The results showed that the release lag time of the tablets increased when the quantity of the plug layer increased thus decreasing the drug release.Plug layer polymers showed a lag time with rank order:SA<NaCMC<HPMC.Selected formulations are F5&F6.F5(having SA as the plug polymer)released valsartan after a lag time of 2 h while F6 released the drug in two successive pulses with a reasonable lag time in between due to its floating behavior.Formulations were stable for at least 3 months under standard long-term and accelerated storage conditions.In conclusion,pulsatile single pulse and floating double pulse stable valsartan core-incup tablets were successfully formulated which provided a desirable lag time followed by a rapid drug release.展开更多
Different samples of igneous and metamorphic rocks from Egypt and Germany have been considered to measure γ-ray activity concentrations due to naturally occurring, potentially hazardous radonuclides 226Ra, 232Th and ...Different samples of igneous and metamorphic rocks from Egypt and Germany have been considered to measure γ-ray activity concentrations due to naturally occurring, potentially hazardous radonuclides 226Ra, 232Th and 40K. The radiation hazard parameters including radiation equivalent activity, gamma-absorbed dose rate, and exter- nal and internal hazard indices have been estimated. The gamma-absorbed dose rates in air of rocks in Egypt range from 4.2 to 128.5 nGy·h-1 with a mean value of 55.3 nGy·h-1. For igneous and metamorphic rocks from Germany, the values of absorbed dose rates fluctuate from 5.1 to 148.6 nGy·h-1, with a mean value of 60.9 nGy·h-1. Generally, it is found that the radiation hazard indices in common igneous rocks are distinctly higher in acidic than in ultrabasic rocks. The results are discussed and compared with the corresponding published data.展开更多
文摘Applying the extreme low-level γ-ray spectroscopic analysis the environmental neutron flux is measured using different moderator construction and environment through the reaction 197Au (n, γ) 198Au. The contribution of thermal and resonance neutrons is separated using the cadmium difference technique, while fast neutrons are measured by the paraffin moderator. The results of altitude dependence of the neutron flux are discussed. The thermal neutron flux near the surface of sea water is less than its value at 100 cm over ground near sea water, while the value over the surfaces of fresh water is higher than that near the surface of sea water. Also the thermal neutron flux at 5 cm soil depth increases, then decreases to its original value at 10 cm depth and still constant until 25 cm, then decreases rapidly to reach 27% of its original value at 60 cm depth. The soil compositions, corresponding neutron temperatures and effective absorption cross sections of earth are the most effective factors on the equilibrium region of thermal neutrons in the ground.
基金Grateful thanks to Prof.Dr.Mohamed H.Zahran,Emeritus Professor of Radiology,Radiology Department,Faculty of Medicine,Alexandria University,for supervision of the X-ray study and his precious support.
文摘The aim of the present study was to design and evaluate single pulse and floating double pulse valsartan core-in-cup tablets.Core tablets were prepared by direct compression of a homogenous mixture of valsartan,Avicel PH-101,Croscarmellose sodium(CCNa),magnesium stearate&Aerosil.Weight variation,Hardness and Disintegration time were measured for the core tablets.Core-in-cup tablets were formulated using different polymers as a plug layer,including sodium alginate(SA),sodium carboxymethylcellulose(NaCMC)and hydroxypropyl methyl cellulose(HPMC).The floating behavior,water uptake and drug release from the prepared formulations were evaluated.Differential Scanning Calorimetry(DSC)was also performed to detect the possible drug excipient interaction.Stability study of the selected formula was performed at 25C&60%RH and at 40C&75%RH for 3 months.Finally,the existence of the selected formula in the stomach after oral administration to human volunteers was verified via x-ray radiography.The results showed that the release lag time of the tablets increased when the quantity of the plug layer increased thus decreasing the drug release.Plug layer polymers showed a lag time with rank order:SA<NaCMC<HPMC.Selected formulations are F5&F6.F5(having SA as the plug polymer)released valsartan after a lag time of 2 h while F6 released the drug in two successive pulses with a reasonable lag time in between due to its floating behavior.Formulations were stable for at least 3 months under standard long-term and accelerated storage conditions.In conclusion,pulsatile single pulse and floating double pulse stable valsartan core-incup tablets were successfully formulated which provided a desirable lag time followed by a rapid drug release.
文摘Different samples of igneous and metamorphic rocks from Egypt and Germany have been considered to measure γ-ray activity concentrations due to naturally occurring, potentially hazardous radonuclides 226Ra, 232Th and 40K. The radiation hazard parameters including radiation equivalent activity, gamma-absorbed dose rate, and exter- nal and internal hazard indices have been estimated. The gamma-absorbed dose rates in air of rocks in Egypt range from 4.2 to 128.5 nGy·h-1 with a mean value of 55.3 nGy·h-1. For igneous and metamorphic rocks from Germany, the values of absorbed dose rates fluctuate from 5.1 to 148.6 nGy·h-1, with a mean value of 60.9 nGy·h-1. Generally, it is found that the radiation hazard indices in common igneous rocks are distinctly higher in acidic than in ultrabasic rocks. The results are discussed and compared with the corresponding published data.
