Mg12O12 and Be12O12 Nanocages as Sorbents and Sensors for H2S and SO2 Gases: A Theoretical Approach.

Theoretical calculations based on the Density Functional Theory (DFT) have been performed to investigate the interaction of H2S as well SO2 gaseous molecules at the surfaces of Be12O12 and Mg12O12 nano-cages. The results show that a Mg12O12 nano-cage is a better sorbent than a Be12O12 nano-cage for the considered gases. Moreover, the ability of SO2 gas to be adsorbed is higher than that of H2S gas. The HOMO-LUMO gap (Eg) of Be12O12 nano-cage is more sensitive to SO2 than H2S adsorption, while the Eg value of Mg12O12 nano-cage reveals higher sensitivity to H2S than SO2 adsorption. The molecular dynamic calculations show that the H2S molecule cannot be retained at the surface of a Be12O12 nano-cage within 300-700 K and cannot be retained on a Mg12O12 nano-cage at 700 K, while the SO2 molecule can be retained at the surfaces of Be12O12 and Mg12O12 nano-cages up to 700 K. Moreover, the thermodynamic calculations indicate that the reactions between H2S as well SO2 with Be12O12 and Mg12O12 nano-cages are exothermic. Our results suggest that we can use Be12O12 and Mg12O12 nano-cages as sorbents as well as sensors for H2S and SO2 gases.

Effect of CO adsorption on properties of transition metal doped porphyrin: A DFT and TD-DFT study.

The structural, electronic and optical properties of transition metal doped porphyrin (TM@P; TM = Mn, Co, Fe, Cu, Ni, Zn) as well as the effect of CO adsorption on TM@P properties have been investigated using the density functional theory (DFT). The presented results include adsorption energies, bond lengths, electronic configurations, magnetic moments, density of states, frontier molecular orbitals, and UV-Vis. spectra. Our calculation results show that, the CO molecule favors to be adsorbed on TM-doped Porphyrin with its carbon head. The most energetically stable adsorption of CO is reported for Fe doped Porphyrin. The interaction between CO molecules with TM@P is attributed to donation-back donation as well as charge transfer mechanisms. Mn, Co and Fe-doped porphyrins have visible active nature which may be affected by CO adsorption, whereas, Ni, Cu and Zn-doped porphyrins have UV active nature which not affected by CO adsorption. These results may be meaningful for CO removal and detection.

Lifetime Measurements of Excited States in

Lifetimes of the first excited 2^{+} and 4^{+} states in the extremely neutron-deficient nuclide ^{172}Pt have been measured for the first time using the recoil-distance Doppler shift and recoil-decay tagging techniques. An unusually low value of the ratio B(E2:4_{1}^{+}→2_{1}^{+})/B(E2:2_{1}^{+}→0_{gs}^{+})=0.55(19) was found, similar to a handful of other such anomalous cases observed in the entire Segré chart. The observation adds to a cluster of a few extremely neutron-deficient nuclides of the heavy transition metals with neutron numbers N≈90-94 featuring the effect. No theoretical model calculations reported to date have been able to explain the anomalously low B(E2:4_{1}^{+}→2_{1}^{+})/B(E2:2_{1}^{+}→0_{gs}^{+}) ratios observed in these cases. Such low values cannot, e.g., be explained within the framework of the geometrical collective model or by algebraic approaches within the interacting boson model framework. It is proposed that the group of B(E2:4_{1}^{+}→2_{1}^{+})/B(E2:2_{1}^{+}→0_{gs}^{+}) ratios in the extremely neutron-deficient even-even W, Os, and Pt nuclei around neutron numbers N≈90-94 reveal a quantum phase transition from a seniority-conserving structure to a collective regime as a function of neutron number. Although a system governed by seniority symmetry is the only theoretical framework for which such an effect may naturally occur, the phenomenon is highly unexpected for these nuclei that are not situated near closed shells.

Pioneering investigation of the characteristics and elemental concentrations in the environment of the declining Wadi Maryut Lake.

Wadi Maryut Lake is one of the remaining parts of the ancient Lake Mareotis and is not mentioned in the scientific literature. For the first time, physical and chemical characteristics as well as elemental concentrations in sediment, water, soil, and plants were determined. The lowest metal pollution indices are in the northeastern end of the lake and tend to increase toward the other end. In lake aquatic environment, Al, Fe, K, Mn, Na, B, and Cr are more likely to exist in insoluble form in the southwestern part and in soluble form in the northeastern part. Using different approaches to assess sediment contamination demonstrates that sediments can be categorized as unpolluted. However, the geo-accumulation index suggests that two locations have low anthropogenic influence of Pb and the enrichment factors and the degree of contamination indicate that Co and Pb may be enriched in sediment of some locations. Comparisons with consensus-based sediment quality guidelines revealed that no sample exceeded the probable effect concentration for Cr, Cu, Ni, Pb, and Zn. The most mobile elements in sediment-water and soil-plant systems are Na, K, and Pb. In sediment-water system, Al, Fe, and Mn oxides have the major influence on scavenging of B, K, and Cr. Similarity in the occurrences of Mn, K, and Fe in soil and Mn and Fe in wild plant was found. This work demonstrates the state of decontamination of the lake and confirms its importance as a reference and comparative case for south Mediterranean coastal water bodies.

Assessment of elemental and NROM/TENORM hazard potential from non-nuclear industries in North Sinai, Egypt.

Non-nuclear industries use raw materials containing significant levels of naturally occurring radioactive material (NORM). The processing of these materials may expose workers engaged in or even people living near such sites to technologically enhanced naturally occurring radioactive material (TENORM) above the natural background. Inductively coupled plasma and gamma ray spectrometry have been used to determine major and trace elements and radionuclide concentrations in various samples, respectively, in order to investigate the environmental impact of coal mining and cement plant in North Sinai, Egypt. Generally, very little attention was directed to the large volumes of waste generated by either type of industrial activities. Different samples were analyzed including various raw materials, coal, charcoal, Portland and white cement, sludge, and wastes. Coal mine and cement plant workers dealing with waste and kaolin, respectively, are subjected to a relatively high annual effective dose. One of the important finding is the enhancement of all measured elements and radionuclides in the sludge found in coal mine. It may pose an environmental threat because of its large volume and its use as combustion material. The mine environment may have constituted Al, Fe, Cr, and V pollution source for the local area. Higher concentration of Al, Fe, Mn, B, Co, Cr, Mn, Ni, Sr, V, and TENORM were found in Portland cement and Zn in white cement. Coal has higher concentrations of Al, Fe, B, Co, Cr, and V as well as (226)Ra and (232)Th. The compiled results from the present study and different worldwide investigations demonstrate the obvious unrealistic ranges normally used for (226)Ra and (232)Th activity concentrations in coal and provided ranges for coal, Portland and white cement, gypsum, and limestone.

Metal concentrations in irrigation canals and the Nile River in an intensively exploited agricultural area.

Concentrations of major and trace elements (Al, Fe, Mn, B, Cd, Co, Cr, Cu, Mo, Ni, Pb, Sr, V, and Zn) were determined in water and sediments from irrigation canals and the Nile River in an agricultural area of 120 km(2) to evaluate the impact of agricultural practices and the spatial distribution and mobility of these elements. The enrichment factors of cadmium indicate contamination in this area. Metal pollution indices are higher at locations downstream of the irrigation canals, possibly a consequence of waste discharges and phosphate fertilizing. Comparisons with consensus-based sediment quality guidelines revealed that ∼92 % (Cr), ∼85 % (Cu), ∼46 % (Ni), and ∼23 % (Zn) of the samples exceeded the threshold effect concentrations, with 7.7 % for Cr and Ni being above the probable effect concentration. Contamination with many metals in water was found in the secondary irrigation canals. The partition coefficients of all determined metals were evaluated. The major elements Al, Fe, and Mn were found to be very mobile while V was the least mobile.

Factors affecting the distribution of natural and anthropogenic radionuclides in the coastal Burullus Lake.

In the present study, measurements of naturally occurring radioactive materials and (137)Cs activity in sediment were conducted for locations covering the entire Burullus Lake in order to gather information about radionuclides mobility and distribution. Low-background γ-spectrometry was employed to determine the activity concentrations of water and sediment samples. The activity concentrations of (226)Ra and (232)Th are close to uniform distribution in the lake environment. Among the different physical and chemical characteristics measured for water and sediment, only salinity and total organic matter content have the potential to affect the mobility of (137)Cs and (40)K. The results suggest that these two radionuclides are attached to different mobile particulates. Increasing salinity tends to strengthen the adsorption of (137)Cs and solubilization of (40)K in sediment. On the other hand, sediment with high organic matter content traps (137)Cs and (40)K associated particulates to bottom sediment.

Forces on cardiac implantable electronic devices during remote magnetic navigation.

BACKGROUND: Remote magnetic navigation systems are used for catheter navigation in cardiac electrophysiological ablation procedures. In this setting, ferromagnetic particles will be moved by changes in the magnetic field. It is unknown to what extent cardiac implantable electronic devices (CIED) are affected by the magnetic field when using magnetic navigation, and whether these forces may exceed the limit of 5 N that is set forth by German and European norms for implanted electrodes. METHODS: A total of 121 rhythm devices were examined in a magnetic field of 0.1 T using the NIOBE II(®) Magnetic Navigation System (Stereotaxis, St. Louis, USA). Forces acting on the devices were measured with the force measurement tool Futek LRF 400 (Futek Advanced Sensor Technology Inc., Irvine, CA, USA). A standardized protocol of different movements of the magnetic field including all three dimensions was performed and maximal forces on the CIED were assessed. RESULTS: Out of 121 devices, 78 different pacemakers (54 different model families from 11 manufacturers) and 43 different cardioverter-defibrillators (26 different model families from 6) were examined. The mean force that could be observed was 0.33 ± 0.13 N for pacemakers (range 0.16-1.12 N) and 1.05 ± 0.11 N for cardioverter-defibrillators (range 0.86-1.38 N) when exposed to the magnetic field. CONCLUSION: Exposure of pacemakers or implantable cardioverter-defibrillators to a magnetic field of 0.1 T does not result in a force exceeding the regulatory demanded 5 N that could damage the connected leads.

Environmental assessment of gamma-radiation levels in stream sediments around Sharm El-Sheikh, South Sinai, Egypt.

A total surface area of ∼170 km(2) including 28 localities around Sharm El-Sheikh, South Sinai, were investigated by γ-ray spectroscopy. The concentrations of NORM were found to be five to seven-fold that in dune sands in different regions in Sinai. While relatively higher levels of (238)U, (234)Th, (226)Ra, and (232)Th are associated with the existing monzo-syenogranite, the concentration of (40)K is more uniformly distributed in the studied area. Locations with higher concentrations of (137)Cs are mainly located in the northern part. The (238)U, (234)Th and (226)Ra isotopes in the (238)U-series are in secular equilibrium. The absorbed dose rates and gamma-radiation hazard indices in all locations were higher than the world average value and unity, respectively. Properly regulated land use is recommended for a buffer zone in the northern part of the study area.

Spatial distribution of radioisotopes in the coast of Suez Gulf, southwestern Sinai and the impact of hot springs.

This work describes the concentrations of radioisotopes in soil, sediment, wild plants and groundwater in southwestern Sinai. The study area extends from Suez to Abu Rudies along the eastern part of the Suez Gulf. It included two hot springs: Ayun Musa and Hammam Faraoun. No dependence of ¹³7Cs concentrations on any of the measured sand characteristics was found, including calcium carbonate. The enrichment of ²²6Ra in Hammam Faraoun hot spring was the most prominent feature. The ²²6Ra concentration in hot springs of Ayun Musa and Hammam Faraoun were 68 and 2377 Bq kg⁻¹ for sediments, 3.5 and 54.0 Bq kg⁻¹ for wild plants and 205 and 1945 mBq l⁻¹ for the groundwater, respectively. In addition, ²²6Ra activity concentration in local sand in the area of Hammam Faraoun was ∼14 times that of Ayun Musa. On the other hand, the ²³²Th concentrations were comparable in the two hot springs, while ¹³7Cs concentrations were relatively higher in Ayun Musa. The characteristics and radioelements studies support possible suggestions that the waters in the two hot springs have different contributions of sea and groundwaters crossing different geological layers where the water-rock interaction takes place.

Inter-comparison study of the population dose due to gamma-radiation in the coast of North Sinai between Rafah and Bir El-Abd areas.

This study compares the external dose due to the gamma-ray emitting radionuclides in various areas in North Sinai, Egypt. The whole area was divided into 10 regions. The average absorbed dose rates were evaluated for each region. It was found that Zaranik-protected area and Al-Massaid have the highest values of 72.7 and 57.2 nGy h(-1), respectively. The corresponding values of the remaining regions were <23 nGy h(-1). The mean annual effective dose equivalents for the four largest cities Rafah, El-Sheikh Zuwaied, Al-Arish and Bir El-Abd were 20.8, 18.8, 57.4 and 14.0 microSv, respectively. The results are compared with those from different areas in Egypt and in various countries.

Reduction of the dimensionality and comparative analysis of multivariate radiological data.

Computational methods were used to reduce the dimensionality and to find clusters of multivariate data. The variables were the natural radioactivity contents and the texture characteristics of sand samples. The application of discriminate analysis revealed that samples with high negative values of the former score have the highest contamination with black sand. Principal component analysis (PCA) revealed that radioactivity concentrations alone are sufficient for the classification. Rough set analysis (RSA) showed that the concentration of (238)U, (226)Ra or (232)Th, combined with the concentration of (40)K, can specify the clusters and characteristics of the sand. Both PCA and RSA show that (238)U, (226)Ra and (232)Th behave similarly. RSA revealed that one or two of them can be omitted without degrading predictions.

Anti-HBc screening in Egyptian blood donors reduces the risk of hepatitis B virus transmission.

Occult hepatitis B virus (HBV) in blood donors is considered as a potential risk for transmission of HBV infection. The aim of this study was to determine the prevalence of anti-hepatitis B core antibody (anti-HBC) positivity in Egyptian blood donations as well as to estimate the frequency of HBV-DNA in anti-HBc-positive donations. The study included 760 Egyptian healthy blood donors, representing 26 different Egyptian governorates screened according to routine practice for the presence of hepatitis B surface antigen (HBsAg), hepatitis C virus (HCV) antibodies (Abs), HIV-1/2 Abs and Treponema Abs. The accepted blood units for donation were tested for the presence of total anti-HBc Abs by two tests. Positive units for anti-HBc were further tested for HBV-DNA by polymerase chain reaction. According to routine screening, a total of 48/760 units (6.3%) were rejected [38 (5%) HCV-Ab-positive units, 9 (1.18%) HbsAg-positive units and 1 (0.13%) Treponema-Ab-positive unit]. Among the accepted blood units for donation, prevalence of anti-HBc was 78/712 units (10.96%). HBV-DNA was detected in 9/78 (11.54%) of the anti-HBc-positive units, and thus, occult HBV infection was detected in 9/712 (1.26%) of the accepted blood donations. Implementing anti-HBc test to the routine assay for the forthcoming two decades would certainly eliminate possible HBV-infected units. Rejection of these units will be beneficial to decrease the risk of HBV transmission with its potential consequences particularly in immunocompromised recipients.

Distribution of gamma-ray emitting radionuclides in the environment of Burullus Lake: I. Soils and vegetations.

The concentrations and distribution of gamma-ray emitting isotopes in Burullus Lake were investigated with the aim of evaluating the environmental radioactivity. Particularly in wetlands, natural properties of the environment can cause the actual inventory to be different from the activity originally deposited. The mean concentrations of (226)Ra, (232)Th and (40)K were 14.3, 15.5 and 224 Bq/kg, respectively, in the coastal soils. On the other hand, soil samples from the islands had mean concentrations of 13.5, 17.4 and 341 Bq/kg for (226)Ra, (232)Th and (40)K, respectively. Samples from coast and islands show evidence of possible transfer and accumulation of the (137)Cs radionuclide. The mean (137)Cs activity concentrations in the soil samples were 1.2 and 15.1 Bq/kg in the coast and islands, respectively. The vertical migration of (137)Cs was studied based on its content in the consequently located three soil layers down to 30 cm depth. The radium equivalent, dose rate in air and annual dose equivalent from the terrestrial natural gamma-radiation were evaluated. The mean activity concentrations of the gamma-ray emitting radionuclides in vegetation were relatively low.

Characteristics, spatial distribution and vertical profile of gamma-ray emitting radionuclides in the coastal environment of North Sinai.

Radionuclide concentrations of beach and dune sand from various sites in Al-Arish city and surrounding area, North Sinai, Egypt, were measured. The sampling sites included locations in the local harbor, Al-Arish valley and Zaranik protected area. The results indicate that the activities of the products of (232)Th and (226)Ra series in samples from the harbor and along the beach were higher than those from non-coastal sites. The activity concentrations of (232)Th for beach sand ranged from 2.3 to 506.5 Bq/kg with an average of 83.4 Bq/kg, while that for dune sand ranged from 2.2 to 15.1 Bq/kg with an average of 6.4 Bq/kg. The average activity concentration of (226)Ra for beach sand was 56.0 Bq/kg (2.9-261.5 Bq/kg), while that for dune sand was 6.5 Bq/kg (3.0-14.7 Bq/kg). The average activity concentrations of (40)K for beach and dune sand were 88.1 Bq/kg and 178.4 Bq/kg, respectively. Six depth profiles in the harbor area were measured up to a depth of 1m within more than two years. These sets of measurements allowed the determination of the migration rate of black sand to be 0.094 cm/day. Samples with the smallest grain size (<0.2 mm) were found to have the highest level of activities, which were attributed to their high content of black sand. No risk exists for public health based on the calculated effective dose equivalent and the recommended limit of 5 mSv/y. On the other hand, local children and adults may receive doses higher than this recommended limit in two locations in the Zaranik protected area according to a model developed in this study.

Levels of 137Cs and 40K in edible parts of some vegetables consumed in Egypt.

The concentrations of (137)Cs and (40)K in some Egyptian foodstuffs have been measured. The results of this study can be considered as a first step towards calculating the baseline levels of radioactivity in foodstuffs in Egypt. Furthermore, the data presented herein can be used as a reference level for future food radioactivity monitoring after the possible operation of the planned nuclear power plants, as well as to screen imported foodstuffs that are suspected of being contaminated. The overall intake of (137)Cs is quite low and no significant radionuclide contamination was found. The highest contents of (137)Cs and (40)K among the tested foodstuffs were in Jew's mallow and roquette. Calculations were also made to determine the potential dose to an individual consuming vegetables.

Prevalence and epidemiological features of hepatocellular carcinoma in Egypt-a single center experience.

Background: The studies carried out on hepatocellular carcinoma (HCC) are scarce in Egypt. Nevertheless, they presumed an upward trend for HCC among chronic liver disease (CLD) patients. The objectives of this research were to determine the trend of HCC, the possible risk factors implicated in its development and the population attributable risk of HCVAb and HBsAg positivity for HCC. Methods: Medical records of all patients attending Cairo Liver Center during the years 1992-1995 were reviewed to determine the sociodemographic characteristics, HCVAb, HBsAg and HCC status. Prospectively, 200 HCC cases' stored sera as well as 120 healthy control were tested for aflatoxin B(1) quantitatively and qualitatively. Results: HCC accounted for 4.7% (321/6850) of CLD patients included in the study. HCVAb positive cases were strikingly high (71.1%) and HBsAg positive cases were reported in 22.4% of patients. There was an annual significant rise of HCC ranging from 3.6% in 1992 to 5.3% in 1995. HCC was significantly more prevalent among old age groups (60 years) than younger age groups. The impact of gender and past history of schistosomiasis on HCC was not proved by this study. HCVAb and HBsAg positivity were the two significant independent risk factors for HCC. The population attributable risk percent has shown that HCC cases attributed to HCVAb positivity accounted for 51.1%; while HBsAg positivity only explained 21.3% of cases. Aflatoxin B(1) was detected in 17% of HCC cases compared to 9.4% of healthy control. Risk ratio=2(95%). Conclusion: HCC is showing an increasing trend among our patients. Its development is mainly due to high rates of HCVAb and HBsAg positivity. HBsAg positive patients were at double risk to develop HCC and HCVAb positive patients were at 1.6 more risk. The high prevalence of HCVAb positivity renders its contribution to the development of HCC over seven-fold higher than HBsAg positivity. Short and long term health strategies are crucial to prevent and control HCC in Egypt.

Effect of monophasic blood flow on the patency of microvascular anastomoses.

The effect of monophasic blood flow on the patency of microvascular anastomoses in the rat femoral artery was evaluated by the authors. An experimental model of monophasic blood flow was created in the rat femoral artery to simulate that seen in patients with peripheral vascular disease. Microvascular anastomoses were performed, and the patency at the first hour and 24 hr later was determined. The studies demonstrated that microarterial anastomotic patency was the same when performed in vessels with monophasic or triphasic flow patterns. The authors conclude that monophasic blood flow is not an absolute contraindication for free-tissue transfer.

Combination treatment of interferon alpha-2b and ribavirin in comparison to interferon monotherapy in treatment of chronic hepatitis C genotype 4 patients.

BACKGROUND AND AIM: Treatment of chronic hepatitis C patients, infected with genotype 4 with interferon-alpha yielded a limited response. Our aim was to compare the efficacy of interferon-alpha alone and in combination with ribavirin in chronic hepatitis C patients infected with genotype 4. PATIENTS: Fifty-two chronic hepatitis C patients (all males) infected with genotype 4, who had not received interferon, were randomized into 2 equal comparable groups. METHODS: Group I received interferon alpha-2b "Schering Plough" 3 MU, tiw combined with ribavirin (1000 mg/day). Group II received interferon alpha-2b alone in the same dose. Both groups were evaluated monthly, at the end of 24 weeks of treatment and 24 weeks later. Two patients were dropped from group I and one patient from group II. RESULTS: Biochemical response: at the end of treatment, a return to normal of ALT was obtained in 16/24 (66.7%) patients on combination therapy vs 8/25 (32%) patients on interferon alone (p = 0.0152). At the end of follow-up, a sustained response was achieved in 10/24 (41.7%) patients on combination therapy vs 4/25 (16%) patients on interferon (p = 0.0468). Virologic response: at the end of treatment, the rates of virological response were higher in the patients on combination therapy 9/24 (37.5%) than in those on interferon 4/25 (16%) (p = 0.0380). At the end of follow-up, loss of serum HCV RNA was reported in 5/24 (20.8%) patients on combination therapy vs 2/25 (8%) patients on interferon (p = 0.1916). Histologic response: mild histologic improvement was shown by a decrease in the inflammatory score, which was highest in patients in the combination group. CONCLUSIONS: In chronic hepatitis C patients infected with genotype 4, combination therapy with interferon-alpha and ribavirin was more effective than treatment with interferon monotherapy. At the end of the follow-up, about 50% of patients in both groups were still viraemic though their ALT remained normal.