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1.
2.
The study focuses on the 2H/H, 13C/12C, 15N/14N, 18O/16O and 34S/32S values of defatted dry matter (DFDM) and on the 2H/H, 13C/12C and 18O/16O values of the fat fraction of meat samples from various lamb types reared in seven Italian regions, following different feeding regimes (forage, concentrate, milk). The 13C/12C (r = 0.922), 2H/H (r = 0.577) and 18O/16O (r = 0.449) values of fat and DFDM are significantly correlated, the fat values being significantly lower for C and H and higher for O than for DFDM values and the differences between the two fractions not being constant for different lamb types. The feeding regime significantly affected the 13C/12C, 15N/14N, 18O/16O and 2H/H of fat. The DFDM 2H/H, and 18O/16O values, excluding an outlier, are significantly correlated with the corresponding values in meteoric waters, thus allowing us to trace the variability of geoclimatic factors. 15N/14N is influenced by pedoclimatic conditions, whereas 34S/32S is influenced by the sea spray effect and the surface geology of the provenance area. By applying stepwise linear discriminant analysis only the 2H/H of fat was found not to be significant and 97.7% of the samples were correctly assigned to the lamb type and more than 90% cross‐validated. With the feeding regime, 97.7% of the samples were both correctly assigned and cross‐validated using a predictive model including 13C/12C, 15N/14N, 18O/16O, 34S/32S of DFDM and 18O/16O of fat. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

3.
A recently discovered phenomenon of excessively high X-ray production is discussed. The high yield is attributed to the build-up of potential on non-conducting targets irradiated with accelerated ion beams, and the subsequent discharge. Ion-beams of1H+,1H2 +,2H+,2H2 +,3He+,3He2+,4He+,14N+,14N2+,16O+ and20Ne+ were used. A new mechanism of X-ray excitation is proposed. The increased X-ray fluxes produced by this process are suitable for analytical applications of high specificity. The mechanism of excitation associated with the process, factors affecting the high X-ray yields, applications and a general overview of the studies undertaken with the various ion beams are given.  相似文献   

4.
Sensitive and selective nuclear reaction methods have been sought for the nuclear microprobe measurement of the spatial distributions of13C and13C/12C ratios. The13C(α, n)16O reaction, with neutron detection, is the most selective for13C, and has a sensitivity of ca. 100 ppm. The reactions13C(d, p)14C and12C(d, p)13C, with proton detection, are the most sensitive for the simultaneous measurement of13C and12C, with detection limits of 30 and 2 ppm respectively. Less sensitive alternative reaction pairs are;13C(3He, p)15N and12C(3He, p)14N;13C(d, nγ)14N and12C(d, pγ)13C;13C(3He, pγ)15N and12C(3He, pγ)14N. The conditions governing their use, particularly light element interferences, are detailed.  相似文献   

5.
Potential energy curves of 22 electronic states of RhN have been calculated by the complete active space second‐order perturbation theory method. The X1Σ0+ is assigned as the ground state, and the first excited state a3Π0+ is 978 cm?1 higher. The 1Δ(I) and B1Σ+ states are located at 9521 and 13,046 cm?1 above the ground state, respectively. The B1Σ+ state should be the excited state located 12,300 cm?1 above the ground state in the experimental study. Moreover, two excited states, C1Π and b3Σ+, are found 14,963 and 15,082 cm?1 above the X1Σ+ state, respectively. The transition C1Π1–X1Σ0+ may contribute to the experimentally observed bands headed at 15,071 cm?1. There are two excited states, D1Δ and E1Σ+, situate at 20,715 and 23,145 cm?1 above the X1Σ+ state. The visible bands near 20,000 cm?1 could be generated by the electronic transitions D1Δ2–a3Π1 and E1Σ+0–X1Σ+0 because of the spin–orbit coupling effect. © 2013 Wiley Periodicals, Inc.  相似文献   

6.
The composition of nickel hexacyanoferrate(II) complexes depends on the ratios of sodium hexacyanoferrate(II) and nickel nitrate solutions mixed. The adsorption behavior of nickel hexacyanoferrate(II) is described; acid treatment of Ni2Fe(CN)6 accelerates the adsorption rate of cesium, but does not increase the adsorption capacity. The Ni—Cs exchange ratios of Ni2Fe(CN)6 are discussed. In concentrated salt solutions, the distribution coefficients of 59Fe, 60Co, 65Zn. 137Cs, 95Zr and 144Ce are determined together with those of 85Sr and 106Ru. A simple determination of 137Cs in sea water containing 59Fe, 60Co, 65Zn, 95Zr, 144Ce, 85Sr and 106Ru is described.  相似文献   

7.
脯氨酸类衍生物结构独特,鲜有报道利用核磁共振(nuclear magnetic resonance,NMR)技术对氨基酸的手性进行鉴别.利用多种NMR技术:1H NMR、1H-1H同核位移相关谱(1H-1H COSY)、1H-1H质子全相关谱(1H-1H TOCSY)、1H-1H核Overhauser效应谱(1H-1H NOESY)、13C NMR、无畸变的极化转移增强法(DEPT135°)、1H-13C检出1H的异核单量子相干(1H-13C HSQC)和1H-13C检出1H的异核多键相关(1H-13C HMBC),对脯氨酸类N-酰胺衍生物两种构象异构体的1H和13C NMR进行了全归属,确定了室温下在二甲基亚砜(DMSO)中L型和D型的顺反异构体以相同的比例同时存在.  相似文献   

8.
Summary Targeted radiotherapy has the potential to provide radiation doses from a wide range of radionuclides, some of them suitable for killing single cells while others are more suitable for killing tumor cell clusters of various sizes. A list of 64 radionuclides, including 20 new potential candidates for therapy (73Ga, 75Se, 87mSr, 97Ru, 103Ru, 113Sn, 113mIn, 117Sb, 123Sn, 131Cs, 139Ce, 141Ce, 149Eu, 167Tm, 170Tm, 173Tm, 195Au, 195mPt, 197Pt and 197Hg) were analyzed in terms of the suitability of their energies for killing tumor cells which grow as single, small, intermediate and large clusters. In addition, their possible production routes were studied.  相似文献   

9.
Summary Excitation functions were measured by stacked-foil technique for the natZn(p,x)61Cu, 66Zn(p,x)61Cu, 68Zn(p,x)61Cu and natZn(p,x)60Cu nuclear processes up to 100 MeV. The experimental cross sections were compared with published data. On the base of these excitation functions, the cross sections of 64Zn(p,x)61Cu process were also deduced. Integral thick target yields were calculated for the 64Zn(p,x)61Cu and nat,64Zn(p,x)60Cu processes and irradiation parameters were elaborated for the 61Cu production via the 64Zn+p reactions for low and middle energy accelerators. According to our calculations the yield of 61Cu amounts to 1.02 . 1011 Bq . A-1 . s-1 (9.9 mCi A-1 . h-1) from 19®10 MeV while it reaches 3.91 . 1011 Bq . A-1 . s-1 (38 mCi . µ A-1 . h-1) in the energy range of 67®60 MeV.  相似文献   

10.
This research was dedicated to the study of the background levels of 210Po and natural gamma emitters as 40K, 214Pb, 214Bi, 228Ac, 212Pb and 212Bi in coffee powder and in coffee beverage; also the artificial 137Cs was determined. In the coffee powder the mean 210Po activity resulted 7.25 ± 2.25 × 10?2 Bq kg?1. 40K showed a mean activity of 907.4 ± 115.6 Bq kg?1. The mean activity concentration of 214Pb and 214Bi, indicators of 226Ra, given as mean value of the two radionuclides, resulted 10.61 ± 4.02 Bq kg?1. 228Ac, 228Ra indicator, showed a mean activity concentration of 13.73 ± 3.20 Bq kg?1. The mean activity concentration of 212Pb, 224Ra indicator, was 8.28 ± 2.88 Bq kg?1. 208Tl, 224Ra indicator, presented a mean activity concentration of 11.03 ± 4.34 Bq kg?1. In all samples, the artifical 137Cs resulted below the detection limit (2.0 Bq kg?1). The arithmetical mean value of percentage of 210Po extraction in coffee beverage resulted 20.5 ± 6.9. The percentage of transfer of gamma emitters,40K, 214Pb, 214Bi, 228Ac, 212Pb, 208Tl resulted of 80.0, 33.5, 24.7, 30.0, 35.1 and 53.5 % for 40K, 214Pb, 214Bi, 228Ac, 212Pb and 208Tl respectively.  相似文献   

11.
From the decay of their most intense -ray, /or rays/, the half-lives of24Na,31Si,49Ca,52V,139Ba,142Pr,153Sm,159Gd,165Dy,166Ho,175Yb,187W,233Th and239U have been redetermined.  相似文献   

12.
The addition of54Mn and65Zn to a nine-radionuclide standard (containing241Am.,109Cd.57Co,139Ce,203Hg.113Sn,137Cs,88Y, and60Co) provides the capability to determine the extent of coincidence summing for gamma rays from88Y and60Co. A method for correcting the efficiency points at 1332 keV (60Co) and 1836 keV (88Y) for coincidence summing is presented.  相似文献   

13.
In the wavelength range of 231-275 nm, we have studied the mass-resolved dissociation spectra of OCS+ via B2+←X23/2(000) and B2+←X21/2(000, 001) transitions by preparing OCS+ ions in the well-defined spin-orbit states. The spectroscopic constants ofυ1(CS stretch)=828.9 (810.4) cm-1, υ2(bend)=491.3 cm-1 and υ3(CO stretch)=1887.2 cm-1 for OCS+(B2+) are deduced. The observed dependence of the υ2(bend) mode excitation of B2+ on the spin-orbit splitting of X2∏(Ω=1/2, 3/2) in the B2+←X2∏ transition can be attributed to the K coupling between the (000)21/2 and (010)2+1/2 vibronic levels of X2∏ state, which makes the B2+(010)←X21/2(000) transition possible.  相似文献   

14.
Probabilities of gamma-ray simultaneous emission have been calculated for the determination of correction factors of full-energy peak areas of radionuclides with a complex decay scheme at measurements of gamma-spectra using HPGe detectors. Coincidence probabilities were determined using the Monte Carlo method for the following radionuclides: 22Na, 24Na, 46Sc, 51Cr, 52Fe, 54Mn, 56Co, 57Co, 58Co, 59Fe, 60Co, 64Cu, 65Zn, 67Cu, 68Ge-68Ga, 75Se, 85Sr, 88Y, 94Nb, 108mAg, 109Cd, 111In, 124Sb, 125Sb, 125I, 131I, 132Cs, 133Ba, 134Cs, 139Ce, 152Eu, 153Sm, 153Gd, 155Eu, 166mHo, 169Yb, 177Lu, 186Re, 207Bi, 208Tl, 212Pb, 212Bi, 241Am.  相似文献   

15.
The cross-sections for the production of the short-lived nuclides:26mAl,197mAu,136mBa,79mBr,139mCe,34Cl,167mEr,114m3In,114m2In,38mK,38mCl,26Na,20F,192Re,207mPb,203mPb,46mSc,183mW,90mZr obtained from (n, 2n), (n, n′), (n, alpha), (n,p) reactions using 14 MeV neutrons, were evaluated by the activation method. The experimental results of this work were compared with those obtained by other authors.  相似文献   

16.
Radioactivity of coals and fly ashes   总被引:1,自引:0,他引:1  
The level and the behavior of the naturally occurring primordial radionuclides 238U, 226Ra, 210Pb, 232Th, 228Ra and 40K in coals and fly ashes are described. The activity concentrations of the examined coals and originated from coal mines in Greece ranged from 117 to 435 Bq·kg−1 for 238U, from 44 to 255 Bq·kg−1 for 226Ra, from 59 to 205 Bq·kg−1 for 210Pb, from 9 to 41 Bq·kg−1 for 228Ra and from 59 to 227 Bq·kg−1 for 40K. These levels are comparable to those appeared in coals of different countries worldwide. The activity concentrations of the examined fly ashes and produced in coal-fired power plants in Greece ranged from 263 to 950 Bq·kg−1 for 238U, from 142 to 605 Bq·kg−1 for 226Ra, from 133 to 428 Bq·kg−1 for 210Pb, from 27 to 68 Bq·kg−1 for 228Ra and from 204 to 382 Bq·kg−1 for 40K. The results showed that there is an enrichment of the radionuclides in fly ash relative to the input coal during the combustion process. The enrichment factors (EF) ranged from 0.60 to 0.76 for 238U, from 0.69 to 1.07 for 226Ra, from 0.57 to 0.75 for 210Pb, from 0.86 to 1.11 for 228Ra and from 0.95 to 1.10 for 40K.  相似文献   

17.
The absolute total and full-energy peak (FEP) efficiencies of a high purity germanium (HPGe) photon detector are measured in the energy range from 40 keV to 1500 keV. The functional parameters are fitted to the calibration points from 14 long-lived standard sources (129I,241Am,109Cd,57Co,139Ce,137Cs,54Mn,65Zn,60Co,22Na,133Ba,152Eu,154Eu and166mHo) within an accuracy better than the quoted uncertainty of the calibration sources. The efficiencies in far and close geometries are compared.  相似文献   

18.
Nuclear proliferation signature radionuclides can be delivered to the aquatic environs via direct liquid discharges or atmospheric routes. The candidate radionuclides for detection are 3H, 90Sr, 95Nb, 95Zr, 99Tc, 106Ru, 125Sb, 129I, 134Cs, 137Cs, 144Ce, 147Pm, NatU, 238U, 235U, 237Np, 239Pu, 240Pu, and 241Pu. The criteria for detection are the limits of radionuclide analysis, the nature and variability of background oncentrations, and the transport characteristics between the source and sample site. The type of sample to be taken is determined by the signature radionuclides sorption on/in the media sampled. Non-sorbing radionuclides such as 3H, 99Tc, and 129I are in the water, whereas the Pu radionuclides are in the transported sediments. Results are discussed for monthly releases of radionuclides such as 90Sr, 137Cs, and 239Pu for variable flow-rate conditions with typical backgrounds and typical detection limits.  相似文献   

19.
By using digital deconvolution to improve spectral resolution, earlier NMR studies on 15N-enriched acetamide have been revised and extended to determine the signs of the heteronuclear spin-spin coupling constants. 1J(13CO15N), 2J(13CH315N) and 3J(C1H315N) are negative while 3J(1H13CH3)>0. The results, interpreted on the basis of the ‘selective decoupling’ formalism, were confirmed by computer simulation of the double resonance spectra. It is shown that 2J(1H-α13CO) is significantly larger than 2J(1HN 13CO). Thus, jointly with {1H-β}-13C′ double resonance experiments, {1H-α}-13C′ experiments ought to be most helpful when assigning peptide group carbonyl resonances. The study provides valuable information for the interpretation of heteronuclear coupling constants in polypeptides.  相似文献   

20.
We have measured the ionic conductivities of pressed pellets of the layered compounds MUO2PO4 · nH2O, and correlated the results with TGA data. The conductivities (in ohm?1 m?1), at temperatures increasing with decreasing water content over the range 20 to 200°C, were approximately as follows: Li+4H2O, 10?4; Li+, Na+, K+, and NH4+3H2O, 10?4, 10?2, 10?4, and 10?4; H+, Li+, and Na+1.5H2O, 10?2, 10?4, and 10?4; Na+1H2O, 10?5; H+, K+, and NH4+0.5H2O, all 10?5; and H+, Li+, Na+, K+, NH+4, and 12Ca2+OH2O, 10?5, 10?5, 10?4, 10?5, 10?5, and 10?6. A ring mechanism is proposed to account for the high conductivity found in NaUO2PO4 · 3.1H2O. The accurate TGA data showed that most of the hydrates had water vacancies of the Schottky type, and should be represented as MUO2PO4(A ? x)H2O, where x can be between 0 and 0.3.  相似文献   

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