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101.
An article by Coulson on the relationhship of physics and mathematics has attracted our attention to problems already discussed by Titchmarsh, namely the distribution of quantum energy levels of a particle confined in a square or a cube with infinite potential-energy walls. These problems are identical to some classical problems in the theory of lattice points, which belongs to number theory. They are seemingly simple, but in fact they are very difficult and not yet completely solved. We summarize the most relevant results from number theory. Whereas the beautiful theorems bearing directly on the error with respect to elementary estimates only provide indications concerning the order of that error; theorems concerning mean values can be used as a basis for a physicist's guess on its asymptotic mean value. This paper has also been intended to contribute to bridging the gap between quantum mechanics and number theory. 相似文献
102.
103.
A theoretical study of charge transfer (CT) characteristics in nitrate (NO3(-)) anion-water complexes is presented, together with those for the halides, F-, Cl-, and Br-, for comparison. The relation between the vibrational frequency red shifts of the hydrogen (H)-bonded OH stretches and CT from the anion to the water molecule, established in previous work for the one-water complexes of the halides, is studied for both the one- and six-water nitrate complexes and is extended to the six-water case for the halides. In NO3(-) x H2O, the water molecule receives about as much charge as that in Br- x H2O. In a result consistent with aqueous phase infrared experiments [Bergstr?m, P. A.; Lindgren, J.; Kristiansson, O. J. Phys. Chem. 1991, 95, 8575-8580], the CT and OH red shift in NO3(-) x 6 H2O are found to be smaller than those for all of the six-water halide complexes, despite the presence of three H-bonding sites. The inability of the nitrate anion to effect substantial CT lies in the preservation of the pi-system being energetically favored over charge localization and enhancement of the strengths of the multiple H-bonds. 相似文献
104.
G. Minero-Ramales D. López-Mancilla Carlos E. Castañeda G. Huerta Cuellar R. Chiu Z. J. Hugo García López R. Jaimes
Reátegui E. Villafaña Rauda C. Posadas-Castillo 《The European physical journal. Special topics》2016,225(13-14):2655-2667
This paper presents a novel electronic locking key based on discrete-time chaos synchronization. Two Chen chaos generators are synchronized using the Model-Matching Approach, from non-linear control theory, in order to perform the encryption/decryption of the signal to be transmitted. A model/transmitter system is designed, generating a key of chaotic pulses in discrete-time. A plant/receiver system uses the above mentioned key to unlock the mechanism. Two alternative schemes to transmit the private chaotic key are proposed. The first one utilizes two transmission channels. One channel is used to encrypt the chaotic key and the other is used to achieve output synchronization. The second alternative uses only one transmission channel for obtaining synchronization and encryption of the chaotic key. In both cases, the private chaotic key is encrypted again with chaos to solve secure communication-related problems. The results obtained via simulations contribute to enhance the electronic locking devices. 相似文献
105.
Yeon Joo Choi Dae Won Kim Min Jea Shin Hyeon Ji Yeo Eun Ji Yeo Lee Re Lee Yejin Song Duk-Soo Kim Kyu Hyung Han Jinseu Park Keun Wook Lee Jong Kook Park Won Sik Eum Soo Young Choi 《Molecules (Basel, Switzerland)》2021,26(11)
Parkinson’s disease (PD) is characterized mainly by the loss of dopaminergic neurons in the substantia nigra (SN) mediated via oxidative stress. Although glutaredoxin-1 (GLRX1) is known as one of the antioxidants involved in cell survival, the effects of GLRX1 on PD are still unclear. In this study, we investigated whether cell-permeable PEP-1-GLRX1 inhibits dopaminergic neuronal cell death induced by 1-methyl-4-phenylpyridinium (MPP+) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). We showed that PEP-1-GLRX1 protects cell death and DNA damage in MPP+-exposed SH-SY5Y cells via the inhibition of MAPK, Akt, and NF-κB activation and the regulation of apoptosis-related protein expression. Furthermore, we found that PEP-1-GLRX1 was delivered to the SN via the blood–brain barrier (BBB) and reduced the loss of dopaminergic neurons in the MPTP-induced PD model. These results indicate that PEP-1-GLRX1 markedly inhibited the loss of dopaminergic neurons in MPP+- and MPTP-induced cytotoxicity, suggesting that this fusion protein may represent a novel therapeutic agent against PD. 相似文献
106.
Güven Kuzey Nur Cemaloğlu Reşit Yakut Mehtap Asmafiliz Nuran Kılıç Zeynel Aydın Betül Açık Leyla Hökelek Tuncer 《Research on Chemical Intermediates》2021,47(10):3933-3962
Research on Chemical Intermediates - The N3P3 ring of hexachlorocyclotriphosphazene, N3P3Cl6 (1) (HCCP; trimer), was used significantly as a scaffold for the syntheses of... 相似文献
107.
Synthesis of Migrastatin Analogues as Inhibitors of Tumour Cell Migration: Exploring Structural Change in and on the Macrocyclic Ring
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Dr. Daniele Lo Re Dr. Ying Zhou Dr. Joanna Mucha Dr. Leigh F. Jones Lorraine Leahy Prof. Corrado Santocanale Prof. Magdalena Krol Prof. Paul V. Murphy 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(50):18109-18121
Migrastatin and isomigrastatin analogues have been synthesised in order to contribute to structure–activity studies on tumour cell migration inhibitors. These include macrocycles varying in ring size, functionality and alkene stereochemistry, as well as glucuronides. The synthesis work included application of the Saegusa–Ito reaction for regio‐ and stereoselective unsaturated macroketone formation, diastereoselective Brown allylation to generate 9‐methylmigrastatin analogues and chelation‐induced anomerisation to vary glucuronide configuration. Compounds were tested in vitro against both breast and pancreatic cancer cell lines and inhibition of tumour cell migration was observed in both wound‐healing (scratch) and Boyden chamber assays. One unsaturated macroketone showed low affinity for a range of secondary drug targets, indicating it is at low risk of displaying adverse side effects. 相似文献
108.
托马斯--杨是一位多才多艺的学者, 在光学、声学、流体动力学、医学、材料力学、
考古学、语言学、保险学等众多领域做出了突出贡献, 但由于种种原因使他在力学方面的贡
献未曾得到学术界的足够重视. 杨在力学方面的研究涉及到材料力学、血液流动力学、能量、
冲击动力学、表面浸润力学、工程结构分析等方面. 他是一位纯粹的自然哲学家, 同时他能
够将理论与实验和工程实际相结合, 实现了后辈力学家所提倡的``技术科学'的理念. 相似文献
109.
Silver(I) fluoride (AgF)-mediated intramolecular nonoxidative and oxidative palladium-catalyzed cyclizations of 1,3-diphenyl- and 8-iodo-1,3-diphenylbenzo[e][1,2,4]triazin-7(1H)-ones 6a (R = H) and 7a (R = I) afford a new 'alkaloid like' ring system 2-phenyl-6H-[1,2,4]triazino[5,6,1-jk]carbazol-6-one 8a (triazafluoranthenone) in 86 and 100% yields, respectively. Furthermore, these cyclization protocols were used to prepare triazafluoranthenone analogues 8b-e bearing dialkylamino, methoxy, and phenylsulfanyl substituents at C-5, which were also independently synthesized from triazafluoranthenone 8a by regioselective nucleophilic addition. Similar AgF-mediated intramolecular nonoxidative and oxidative palladium-catalyzed cyclizations of 8,10-dihydro-1-iodo-10-phenylphenazin-2(7H)-ones 13 gave the new 'alkaloid like' ring system 8H-indolo[1,2,3-mn]phenazin-8-one 14 in 80 and 18% yields, respectively. 相似文献
110.
A novel fiber optic spectrophotometric determination of nitrite using Safranin O and cloud point extraction 总被引:1,自引:0,他引:1
A novel fiber optic spectrophotometric method for nitrite determination in different samples is suggested, based on the reaction of nitrite with Safranin O in acidic medium to form a diazo-safranin, which is subsequently coupled with pyrogallol in alkaline medium to form a highly stable, red azo dye, followed by cloud point extraction (CPE) using a mixed micelle of a nonionic surfactant, Triton X-114, with an anionic surfactant, sodium dodecyl sulphate (SDS). The reaction and extraction conditions (e.g., acidity for diazotization and alkalinity for pyrogallol coupling, and other reagent concentrations, time, and tolerance to other ions) were optimized. Linearity was obeyed in a concentration range up to 230 μg L−1, and the detection limit of the method is 0.5 μg L−1 of nitrite ion. The molar absorptivity for nitrite of the Safranin-diazonium salt (?610 nm = 4 × 103 L mol−1 cm−1) existing in literature was greatly enhanced by pyrogallol coupling and CPE enrichment (?592 nm = 1.39 × 105 L mol−1 cm−1). The method was applied to the determination of nitrite in tap water, lake water and milk samples with an optimal preconcentration factor of 20. 相似文献