Search Results
You are looking at 61 - 70 of 75 items for
- Author or Editor: A. Khan x
- Refine by Access: All Content x
Abstract
Trace amounts of boron present as impurity in steel can be accurately determined by measuring the α-yield in10B (n,α)7Li reaction, since this reaction has a very high cross section for thermal and epithermal neutrons while natural boron contains significant isotopic abundance of10B. The α-particles produced during10B (n,α)7Li nuclear reactions can be detected by solid state nuclear track detectors (SSNTDs) and the boron content and its distribution can be determined in a sample. The technique involves the simultaneous irradiation of unknown and known samples with thermal neutrons and recording the reaction products in SSNTDs as α-tracks. The α-tracks in the detectors are counted with the aid of an optical microscope after chemical etching. Boron concentration and distribution in the unknown sample is determined by counting and comparing the track density with that of standard sample of known boron concentration. The technique of SSNTDs has been applied by us to determine the distribution of trace amount of boron in commercial alloy steel using LR-115, CA80-15, CN-85 and CR-39 detectors. All these detectors pose various problems during reactor irradiation and etching. However, CR-39 has been found to be suitable for determining the magnitude and distribution of boron in steel. A brief description of the method and the optimum irradiation and etching conditions of various detectors for α-track revelation along with results for the estimation of boron in alloy steel are described in this paper.
The solid-state deaquation of thetrans- andcis-oximates of lawsone (I) and phthiocol (II) with cobalt(II) was investigated by means of non-isothermal thermogravimetry. The modes of deaquation during the thermolyses of hydrated oximates of (I) and (II) with compositions CoL2·2H2O were compared. The weight lossvs. temperature data were treated by using the Coats and Redfern relations. The kinetic data support a rearrangement-type mechanism for the deaquation of the oximate of phthiocol. TheE a values for both the ligands and water molecules were found to be ∼23 kJ/mol.
Abstract
The trace element composition of whole blood has been investigated in adult population in Bangladesh. The population was formed of one hundred individuals randomly selected from a working community of five hundred adults. The blood samples were freeze dried and analyzed using the external beam PIXE method. In this analysis, proton beams of 2 MeV energy and about 30 nA current were used for characteristic X-ray excitation. The concentration of eight elements, K, Ca, Fe, Cu, Zn, Br, Rb and Pb were determined by comparison with a calibration obtained from NBS orchard leaves. The frequency distributions of all the elements measured are presented and the results are compared with available data.
A study was conducted on the sheep farm of the Livestock Experimental Station, located in the southwestern Punjab, Pakistan, to determine the copper nutrition status of different classes of grazing sheep during two different seasons. A complete free-choice supplement (feed) was available to all animals throughout the year. The purpose of this research was to investigate, as a function of the seasons, the transfer of Cu from soil, and dietary factors to sheep grazing in this semiarid region, in order to evaluate if the Cu requirement of grazing livestock was met or if a deficiency occurred. The final goal was to maximize the production of the animals by adopting, if necessary, adequate, balanced Cu supplementation. Soil, forage, feed and water samples, and animal samples (plasma, milk, faeces and urine from lactating ewes, plasma, faeces and urine from non-lactating ewes and plasma and faeces from male animals) were taken eight times during the year (four times in each season). Soil copper was affected by the seasonal changes and sampling intervals and was significantly higher than plant needs during both seasons, while the forage copper level did not show significant seasonal fluctuations, but was only affected by the sampling intervals. The soil and forage Cu was sufficient for the requirements of the plants and the animals grazing there on during both seasons. The copper contents of the feed and water showed no seasonal or sampling interval fluctuations. The plasma Cu was affected by seasonal variations in non-lactating ewes and in rams and by sampling intervals in the lactating ewes. Faecal and urine Cu was not affected by seasonal or sampling intervals except in non-lactating ewes, where the sampling interval had a pronounced effect on faecal Cu, while milk Cu in lactating ewes was affected by seasonal changes only. In all classes of sheep plasma Cu was higher during the winter than during the summer and remained in the normal range for ruminants during both seasons. It is concluded that a mixture with high bioavailability, containing Cu, should be continuously provided to grazing sheep in this semi-arid region in order to maintain the normal level of Cu and maximize the production potential of ruminants.
Extensive research on Ficus species has shown their excellent cytotoxic potential which motivated the authors for further evaluation of its other species. In this article, the β-sitosterol content in the chloroform extract of the leaves of five Ficus species (Ficus carica [FCCE], Ficus nitida [FNCE], Ficus ingens [FICE], Ficus palmata [FPCE], and Ficus vasta [FVCE]) was estimated by a validated high-performance thin-layer chromatography (HPTLC) method along with cytotoxic activity. The chromatography was performed on glass-backed silica gel 60 F254 HPTLC plates with hexane and ethyl acetate (8:2, v/v) as the mobile phase. The developed plate was derivatized with p-anisaldehyde reagent, scanned, and quantified at λ = 550 nm. It furnished a compact and intense peak of β-sitosterol at R F = 0.17 ± 0.001. The contents of β-sitosterol (μg mg−1 of the dried weight of the extract) in the selected Ficus species were found as: FCCE (1.047 μg mg−1) > FVCE (0.771 μg mg−1) > FNCE (0.372 μg mg−1) > FPCE (0.309 μg mg−1), while it was absent in F. ingens. Methylthiazol tetrazolium (MTT) assay was used to compare the cytotoxic potential of all Ficus species against HepG2 (liver), HEK-293 (kidney), MCF-7 (breast), and MDA-MB 231 (breast) cell lines. The FCCE exhibited good cytotoxic property against HepG2, HEK-293, and MDA-MB-231 cells (IC50: 32.5, 41.4, and 47.3 μg mL−1, respectively), while FICE showed against HepG2 and MDA-MB-231 cells (IC50: 31.4 and 41.2 μg mL−1, respectively). The remaining Ficus extracts were found to be very less effective or insignificant. The cytotoxic property of FCCE is also supported by the HPTLC estimation of β-sitosterol which is reported to exhibit anticancer properties by interfering with multiple cell signaling pathways, including cell cycle, apoptosis, and proliferation. Our data suggest that the developed HPTLC method can be further employed in the analysis of marketed herbal formulations, and the active Ficus species can be further subjected to isolation of cytotoxic phytoconstituents.
Abstract
Platelet-rich plasma (PRP) has emerged as a cornerstone in veterinary regenerative medicine. The present study evaluated the impact of the operator on the qualitative and quantitative features of non-activated PRP derived from canine whole blood. Blood was collected in anticoagulant acid citrate dextrose from twelve healthy adult dogs and PRP was prepared according to the double-spin method. Both operators followed an identical protocol and utilized the same equipment for PRP preparation from the pooled blood samples. The resulting PRP underwent characterization, classification and coding based on minimum reporting standards. The consistency and internal reliability of different parameters were also assessed using the intraclass correlation coefficient and Cronbach's alpha values. Variables such as white blood cell (WBC) concentration, relative WBC composition and mean platelet volume (MPV) showed poor reliability, and WBC concentration and MPV also had unacceptable internal consistency. Significant differences were observed in several qualitative and quantitative parameters of the prepared PRP, highlighting the influence of the operator even when the same protocol and equipment were used. Our study has direct implications to regenerative medicine, reinforcing the urgency to set minimum requirements for reporting PRP in research studies.
Abstract
An investigation is conducted on the status of trace and minor elements in some foodstuffs (cereals, vegetables, milk, egg and fish), commonly consumed in Bangladesh, using proton induced X-ray emission (PIXE) and radioisotope-induced X-ray fluorescence (XRF) techniques. In PIXE measurements, the samples were irradiated in air with 2.0 MeV (energy on the target) protons having the beam intensity of 30 nA for characteristic X-ray excitation, while in XRF analysis, the samples were excited for 5000 seconds with a 10 mCi Cd-109 annular X-ray source. The elemental concentration of K, Ca, Mn, Fe, Ni, Cu, Zn, Se, As, Br, Rb, Sr, Mo, and Pb were determined in the samples by comparison with X-ray yield curves constructed from IAEA and NBS standard reference materials. The validity of the analytical procedures (PIXE and XRF) followed in this study has been confirmed by comparative measurements of Cu, Zn and Mn in some varieties of rice with atomic absorption spectrophotometry. The results indicate that none of the food regimes investigated here is burdened with heavy metals beyond permissible limits except five species of vegetables with chromium having the range of 0.99–3.59 mg/kg compared to the literature value of 0.0–0.36 mg/kg (dry weight basis). An average value of 0.2 mg/kg of arsenic was observed both in IRRI (n=16) and local Aman (n=12) varieties of rice and only one hen egg contained 1.7 mg/kg of lead in yolk. The zinc content in some marine fish from Bay of Bengal was reported to be 5.4–19.5 mg/kg, whereas in the present study of sweet-water fish, the level is found to be 15.2–62.1 mg/kg (fresh weight basis) for five species. In human milk, both Cu (0.12–0.25 mg/l, n=8) and Zn (0.28–1.80 mg/l, n=8) levels appear to be almost half the literature values (n=25). On the other hand formula milk has higher values of Cu (0.32–1.63 mg/kg, n=16) and Zn (5.16–19.8 mg/kg, n=16).
Although the antimicrobial activity of the engineered nanoparticles (NPs) is well known, the biochemical mechanisms underlying this activity are not clearly understood. Therefore, four NPs with the highest global production, namely SiO2, TiO2, ZnO, and Ag, were synthesized and characterized. The synthesized SiO2, TiO2, ZnO, and Ag NPs exhibit an average size of 11.12, 13.4, 35, and 50 nm, respectively. The antimicrobial activity of the synthesized NPs against bacteria and fungi were also determined. NPs-mediated inhibition of two very important enzymes, namely urease and DNA polymerase, is also reported. The synthesized NPs especially Ag and ZnO show significant antimicrobial activity against bacteria and fungi including methicillin-resistant Staphylococcus aureus even at low concentration. The DNA polymerase activity was inhibited at a very low concentration range of 2–4 µg/ml, whereas the urease activity was inhibited at a high concentration range of 50–100 µg/ml. Based on their ability to inhibit the urease and DNA polymerase, NPs can be arranged in the following order: Ag > ZnO > SiO2 > TiO2 and Ag > SiO2 > ZnO > TiO2, respectively. As the synthesized NPs inhibit bacterial growth and suppress the activity of urease and DNA polymerase, the use of these NPs to control pathogens is proposed.
Abstract
Pyrolysis of trisbipyridineiron(II) chloride under controlled thermal conditions and inert atmosphere of argon gas yields a residue of iron nanoparticles. Evolved gas analysis by GC–MS and 1H NMR revealed emission of bipyridine, 6-chlorobipyridine, 6,6′-dichlorbipyridine, bipyridine hydrochloride, and hydrochloric acid as decomposition products. CHN, XRPD, EDXRF, TEM, AFM, and 57Fe Mössbauer spectroscopy of the residue indicated formation of pure iron nanoparticles in the size range of 50–72 nm. Based on these results a mechanism for thermal degradation of trisbipyridineiron(II) chloride has been worked out.
Bacillus thuringiensis (B.t) is well known for its biocontrol potential against a variety of insects. Nematicidal potential of ten B.t isolates was tested against root-knot nematodes (Meloidogyne javanica (Treub) Chitwood) in vitro, under greenhouse as well as in field conditions. Eggs and second stage juveniles (J2) were exposed to 5 and 25% concentrations of bacterial cell-free aqueous extracts up to 96 h. B.t isolates showed lesser degrees of nematicidal activity at 5% concentration. However, some B.t isolates (B.t-14, B.t-16 and B.t-64) greatly reduced egg hatching and increased J2. All B.t isolates revealed suppressed egg hatching and increased mortality of J2 at 25% concentration. Soil applications with most of the B.t isolates under greenhouse and field conditions significantly improved height and fresh weights of root-knot nematode parasitized okra (Abelmoschus esculentus (L.) Moench). Some isolates, including B.t-64 reduced the number of galls and egg masses. B.t-64 reduced gall formation up to 70% under greenhouse conditions. However, 29% of decrease was observed in field conditions. Similarly, B.t-64 treated plants showed a 56% decreased in eggs/egg mass in a field experiment. Population of root-knot nematodes in the rhizosphere was decreased up to 61% in the field experiment as compared to control.
