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We discuss the notion of spin squeezing considering two mutually exclusive classes of spin-s states, namely, oriented and non-oriented states. Our analysis shows that the oriented states are not squeezed while non-oriented
states exhibit squeezing. We also present a new scheme for construction of spin-s states using 2s spinors oriented along different axes. Taking the case of s=1, we show that the ‘non-oriented’ nature and hence squeezing arise from the intrinsic quantum correlations that exist among
the spinors in the coupled state. 相似文献
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Niloofar Jalilian Ali Akbar Asgharinezhad Homeira Ebrahimzadeh Karam Molaei Sara Karami 《Chromatographia》2018,81(11):1569-1578
In this work, surfactant-coated Fe3O4@decanoic acid nanoparticles was synthesized as a viable nanosorbent for coextraction of drugs with different polarities (hydrophobic, hydrophilic). To reach desirable enrichment factors, efficient clean-up and low limits of detection (LODs), the method was combined with dispersive liquid–liquid microextraction (DLLME). The coupling of these extraction methods with GC-FID detection was applied to simultaneous extraction and quantification of venlafaxine (VLF) as a hydrophilic model drug and desipramine (DESI) and clomipramine (CLO) as hydrophobic model drugs in urine samples. The effect of sample pH, nanosorbent amount, sorption time, surfactant concentration, eluent type, eluent volume, salt content, elution time in magnetic solid phase extraction step and extraction solvent and its volume along with sample pH in DLLME step were optimized. Under the selected conditions, linearity was achieved within the range of 5–5000 µg L?1. The LOD values were obtained in the range of 1.5–3.0 µg L?1 for DESI, 1.2–2.5 µg L?1 for VLF and 2.0–4.0 µg L?1 for CLO, respectively. The percent of extraction recoveries and relative standard deviations (n?=?5) were in the range of 82.4–95.9 and 6.1 for DESI, 60.5–92.8 and 6.9 for VLF and 57.2–58.0 and 5.5 for CLO, respectively. Ultimately, the applicability of the new method was successfully confirmed by the extraction and quantification of DESI, VLF and CLO from human urine samples. 相似文献
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胶体粒子聚集速率常数实验值远低于理论值一直是被普遍关注的问题.聚集速率常数的理论推导是基于粒子的几何半径来考虑的,但决定粒子扩散速率及聚集速率的应该是粒子的流体力学半径(大于几何半径),因而它是使聚集速率常数实验值低于理论值的因素之一.影响流体力学半径的因素很多,其中,带电粒子在溶液中因表面存在双电层,会明显增大流体力学半径,造成聚集速率减慢.而双电层的厚度又随溶液中离子强度的不同而改变.本工作在聚集速率的公式中引入了修正因子,即几何半径与其流体力学半径之比,以修正由于用几何半径代替流体力学半径带来的误差.其中几何半径和流体力学半径可以分别用扫描电镜(SEM)和动态光散射(DLS)来测定.以两种粒径的聚苯乙烯带电微球为例,考察了在不同离子强度下,该误差的大小.结果发现,对于半径为30 nm的微球,用流体力学半径计算的慢聚集速率常数比理论值偏低约8%.该误差随离子强度增加而减少.对于快聚集情况,流体力学半径对聚集速率基本没有影响. 相似文献
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Amita Gupta Alexei Yu Ganin Parmanand Sharma Vikrant Agnihotri LM Belova KV Rao Mikhail E Kozlov AA Zakhidov RH Baughman 《Pramana》2002,58(5-6):1051-1059
We present studies of novel nanocomposites of BiNi impregnated into the structure of opals as well as inverse opals. Atomic force microscopy and high resolution elemental analyses show
a highly ordered structure and uniform distribution of the BiNi filler in the matrix. These BiNi-based nanocomposites are
found to exhibit distinct ferromagnetic-like ordering with transition temperature of about 675 K. As far as we know there
exists no report in literature on any BiNi compound which is magnetic. 相似文献
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Ali Akbar Asgharinezhad Homeira EbrahimzadehFatemeh Mirbabaei Narges MollazadehNafiseh Shekari 《Analytica chimica acta》2014
In this study, diverse types of Fe3O4 nanocomposites modified by polyaniline, polypyrrole, and aniline–pyrrole copolymer were synthesized through chemical oxidative polymerization process for dispersive-μ-solid phase extraction (D-μ-SPE) in the presence of various dopants. The results showed that the nanocomposite modified by polyaniline with p-toluene sulfonic acid as a dopant demonstrated higher extraction efficiency for lorazepam (LRZ) and nitrazepam (NRZ). Also the synthesized magnetic sorbents were characterized. The nanocomposite sorbent in combination with high performance liquid chromatography–UV detection was applied for the extraction, preconcentration and determination of lorazepam and nitrazepam in urine and plasma samples. Different parameters influencing the extraction efficiency including: sample pH, amount of sorbent, sorption time, elution solvent and its volume, salt content, and elution time were optimized. The obtained optimal conditions were: sample pH, 6; amount of sorbent, 5 mg; sorption time, 5.0 min; elution solvent and its volume, 0.5 mM cethyltrimethyl ammonium bromide in acetonitrile, 150 μL; elution time, 2.0 min and without addition of NaCl. The calibration curves were linear in the concentration range of 1–2000 μg L−1. The limits of detection (LODs) were achieved in the range of 0.5–1.8 μg L−1 for NRZ and 0.2–2.0 μg L−1 for LRZ, respectively. The percent of extraction recoveries and relative standard deviations (n = 5) were in the range of 84.0–99.0, 6.1–7.8 for NRZ and 90.0–99.0, 4.1–7.0 for LRZ, respectively. Ultimately, the applicability of the method was successfully confirmed by the extraction and determination of NRZ and LRZ in human urine and plasma samples. 相似文献
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Darshan C Kundaliya Reeta Vij AA Tulapurkar U Vaidya R Pinto RG Kulkarni 《Pramana》2002,58(5-6):1041-1044
Electrical resistance (R) measurements of a bulk La0.33Nd0.33Ca0.33MnO3 perovskite in magnetic fields up to 40 kOe have revealed anomalous temperature hysteretic effects both in 0 Oe and 20 kOe
magnetic fields. The sharp peak observed in the R vs. T plot indicates the occurrence of metal-to-insulator (M-I) transition at a temperature of T
MI=110 K and 140 K, for cooling and warming paths, respectively. An applied magnetic field of 20 kOe reduces the resistance
and shifts T
MI to 160 K and 185 K for cooling and warming, respectively. We have observed a much higher resistance in the cooling path than
in the warming path leading to the hysteretic resistance ratio (R
cool/R
warm) of 200 at 110 K and 1.8 at 160 K for 0 Oe and 20 kOe, respectively. Record values of colossal magnetoresistance (CMR) have
been achieved. The CMR value reaches nearly 99% in the temperature ranges of 90 K to 140 K and 90 K to 170 K for 20 kOe and
40 kOe magnetic fields in the cooling mode, respectively. The observed unusual behavior is attributed to the co-existence
of La-rich and Nd-rich domains assumed to be distributed randomly in the compound. 相似文献
20.
We have studied the peak effect (PE) phenomenon in single crystals of weakly pinned superconductors CeRu2 and 2H-NbS2. 2H-NbS2 is iso-structural and iso-electronic to 2H-NbSe2, whose similarity with CeRu2 as regards the PE representing the order-to-disorder transformation of the flux line lattice was claimed some time ago. We
report on the step change in equilibrium magnetization across the peak effect in CeRu2. We also present the vortex phase diagram of 2H-NbS2 obtained from the magnetization data, and compare the PE phenomenon in 2H-NbS2 and 2H-NbSe2. 相似文献