Study of radon in ground water and physicochemical parameters in Khartoum state

This study was conducted primarily to measure and map radon activity concentration in wells within water supply network of Khartoum State. Ground water samples were collected before and after autumn and analysed using low level γ-spectrometry equipped with HPGe-detector. Radon activity concentration was found in the range of 1.58–345.10 Bq/L with an average value of 59.20 ± 6.60 Bq/L. Upon comparing the radon concentration values obtained with EPA it was found they were far below the maximum contaminant level of EPA with the exception five samples. Physicochemical water parameters were measured and no correlation was noted between radon concentration and these parameters. The overall annual effective dose for adults due to radon ingestion is less than WHO recommended reference dose level for most except 14 samples.     

EFFECT OF COMPOSITION AND PROCESSING CONDITION ON MICROSTRUCTURAL PROPERTIES AND DURABILITY OF FLUOROPOLYMER/ACRYLIC BLENDS

Fluoropolymer blends have been widely used as binders for exterior coatings because of their excellent resistance to ultra-violet (UV) radiation as well as to many corrosive chemical agents.It is known that the fluorinated component usually has a lower glass transition temperature and easily crystallizes in the final structure depending upon the blend composition and sample annealing condition.We investigated the effect of blend composition and annealing process (slow and fast cooling) on the surface mor...     

Determination of 226Ra, 232Th and 40K in teeth by use of gamma spectroscopy

This study entails the measurement of the specific activity of natural radionuclides (²²⁶Ra, ⁴⁰K and ²³²Th) in 18 tooth samples obtained from the clinic of the Universiti Sains Malaysia (USM), Penang, by using an HPGe detector. The specific activity of ²²⁶Ra, ⁴⁰K and ²³²Th was measured to estimate the hazard index of the radionuclides, radium equivalent activities (Ra_eq), external, internal hazard indices (H_ex, H_in), and absorbed dose (D_out, D_in). The maximum values of concentration of ²²⁶Ra, ²³²Th and ⁴⁰K in the tooth samples were found to be 60.82, 60.29 and 594.22?Bq kg^?1, respectively. Maximum values of Ra_eq, H_ex, H_in, D_out and D_in were found to be 192.78?Bq kg^?1, 0.520, 0.685, 89.29 and 169.81?nGy h^–1, Iγ and Iα as 0.702 and 0.304, respectively. The results were lower than the average world value (UNSCEAR). In addition, a strong correlation was found between the concentrations of ²²⁶Ra and Ra_eq, between energy and net area, as well as between radionuclides (²²⁶Ra, ⁴⁰K and ²³²Th) in tooth samples and age of volunteers. This study showed that the concentrations and hazard indices of tooth samples are below the recommended safe levels; therefore, the study area is considered safe in terms of radiological health hazards.     

Decoherence via the dynamical casimir effect

We derive a master equation for a mirror interacting with the vacuum field via radiation pressure. The dynamical Casimir effect leads to decoherence of a superposition state in a time scale that depends on the degree of "macroscopicity" of the state components, and which may be much shorter than the relaxation time scale. Coherent states are selected by the interaction as pointer states.     

The mass attenuation coefficients in some vanadium and nickel compounds

The mass attenuation coefficients for V₂O₃, VO₂, VF₃, NH₄VO₃, VF₄, NiF₂, NiCl₂, NiCl₂H₂O, NiF₂4H₂O, NiCl₂6H₂O, Ni(ClO₄)₂6H₂O were measured in the X-ray energy range from 15.746 to using a Si(Li) detector. The measured values are compared with the theoretical ones calculated using WinXcom.     

Who touched the document?: A new overall strategy for collection and identification of DNA from the questioned documents as a supportive evidence

The questions on which judges/prosecutors apply for expertise are mostly about by whom a document was drafted/signed. In this study, a new collective strategy was constructed including a collection method, a modified-silica-based DNA isolation method, and a novel purification method on four contact traces formed on four different paper surface during writing, using PCR with AmpFlSTR®GlobalFiler™ STR kit (after experimental comparison between three different kits) and identification using CE. This collective analysis approach is more sensitive and superior to its equivalents on questioned documents in literature because quantifiable amounts of touch DNA and profiles with high loci percentages (100% on day 1, 72.72% after 1 week) were obtained up to 1 week even after the most challenging conditions of sample forming that a forensic scientist can meet; as washing hands just before drafting and using a very low pressure in a shorter time (simulating a simple contact real conditions while drafting), using no visualizing technique that damages the document. Using the strategy, four most commonly used paper types were compared, to see in which of them DNA could be recovered better. The success of this strategy was shown on the 1-day to 10-year-old real samples from a diary and some archive documents from a law office (including the mix-DNA and different ballpoint pens). Thus, it became possible to show if a person had touched the document, in high success rates up to 1 week as a secondary evidence, when primary evidences are insufficient for the detection of document fraud offenses.     

Validated method for occupational cyclophosphamide monitoring using LC-MS/MS and a Poroshell 120 column

Pharmacy staff and health care workers in hospitals may be exposed to antineoplastic drugs during cancer chemotherapy. Sensitive methods should be used to monitor the occupational exposure in biofluids such as urine. In this study, a sensitive method for cyclophosphamide determination in urine with high recovery was developed and validated for monitoring occupational exposure. Triple liquid-liquid extraction with ethyl acetate/dichloromethane (φ_r= 3:1; 6.0 mL) was applied. Good separation of cyclophosphamide and ifosfamide was achieved in a 9.0 min analysis, using liquid chromatography combined with tandem mass spectrometry (LC-MS/MS). Limit of detection and limit of quantification were 0.07 ng mL^?1 and 0.11 ng mL^?1, respectively. Repeatability (RSD, %) was ≤ 12.74%. Inter-day and inter-analyst precision values (RSD, %) were ≤ 13.94% and 12.59%. Mean recovery for three different concentrations was (101.62 ± 6.05) %. The validation results were fitted for the purpose of routine monitoring of occupational cyclophosphamide exposure in hospital staff.     

A fast method for monitoring of organic explosives in soil: a gas temperature gradient approach in LC–APCI/MS/MS

A novel, fast liquid chromatography atmospheric pressure chemical ionization mass spectrometry (LC–APCI–MS/MS) screening method was developed to determine the trace amounts of TNT (trinitrotoluene), RDX (1,3,5-trinitroperhydro-1,3,5-triazine), HMX (cyclotetramethylene-tetranitramine), PETN (pentaerythritoltetranitrate), TETRYL (2,4,6-trinitrophenyl-N-methylnitramine), picric acid (2,4,6 trinitrophenol), 2,6-DNT (2,6-dinitrotoluene), and TMETN (trimethylolethane-trinitrate) which contaminate the soil after explosion. A gradient of 2.00 mM ammonium nitrate aqueous solution-methanol mobile system, C18 column, and atmospheric pressure chemical ionization (APCI) (?) ionization mode was used after a single-step solid–liquid extraction procedure from soil matrix. Phenytoin was used as the internal standard. As an extraordinary application, gas temperature gradient in an APCI ionization was used. Analytes were selectively eluted from the system within 10 min. Average recovery obtained from the soil was between 93.01 and 104.20% at 250.0, 500.0, and 1000.0 ngg^?1 concentration levels. Limit of detection (LOD) and limit of quantification (LOQ) values obtained from the analysis of the soil samples including explosive mix were between 8.9–161.2 and 13.2–241.5 ngg^?1, respectively.     

Matrix-assisted laser desorption/ionization Fourier transform mass spectrometry of luteinizing hormone releasing hormone-metal ion complexes

Complexes of luteinizing hormone releasing hormone (LHRH) with divalent metal ions (Ni, Zn, Cu) have been studied by matrix-assisted laser desorption ionization (MALDI) and Fourier transform mass spectrometry. LHRH-metal complexes were detected in high abundance for all three metals from synthesized samples, particularly in negative ion mode. The mixture of the apopeptide with the metal salts yielded in most cases a very minor signal of metal-complex ions. As opposed to Ni and Zn, copper complex ions were mostly observed as Cu(I) adducts. This can be partly attributed to plume reactions of Cu(I) with the apopeptide. the Cu(II) complexes appeared only for the synthetic complex. We show how to distinguish between the contribution to the overall signal from desorbed complexes and from Cu(I) complexes formed in the MALDI plume.     

Metformin Containing Nickel (II) Complexes: Synthesis,Structural Characterization,Binding and Kinetic Interactions with BSA,Antibacterial and in-vitro Cytotoxicity Studies

In quest of antimicrobial and anticancer agents, metformin containing Ni (II) complexes, [Ni (Met)₂]Cl·OH ( 1 ) and [Ni (Met)(IDA)] ( 2 ) {Met: metformin, IDA: iminodiacetic acid} were synthesized and X-ray structure of 1 is four-coordinate square planar geometry. Bovine serum albumin (BSA) interaction and binding studies to Met, IDA and their Ni (II) complexes were investigated and showed a strong interaction. A static quenching process was proposed at low concentrations of compounds whereas, combined quenching process was observed for 1 and 2 at higher concentrations. Kinetic stability, affinity and association constants of compounds-BSA were studied using stopped-flow technique and a mechanism was proposed: a fast and reversible step of BSA binding including complex formation and dissociation was proposed; for the second step, a reversible reaction was observed for 1 and 2 whereas, an irreversible reaction with Met and IDA was observed indicating that coordination with nickel ions change the interaction mechanism. Additionally, the antibacterial investigation against both Gram-positive and Gram-negative bacteria showed that all compounds exhibited significant activities. They also show cytotoxicity against HepG2 human liver cancer cell but the half maximal inhibitory concentration (IC50) values obtained for the cell lines were higher in comparison with cisplatin. Although Met-BSA and IDA-BSA are kinetically more stable than that of 1 -BSA and 2 -BSA, 1 -BSA and 2 -BSA showed better antibacterial and cytotoxic activities which is in agreement with the binding constants.