Volumetric q-space imaging by 3D diffusion-weighted MRI

High b-value diffusion magnetic resonance imaging (MRI) enables us to detect far smaller architectures, by using q-space analysis, than the resolution in conventional MRI. Average displacement, one of the q-space parameters, quantitatively reflects architecture size and is very useful in observing small changes in microstructures in vivo (e.g., neurodegeneration, tumor heterogeneity, and others). Diffusion-weighted imaging (DWI) is performed by a two-dimensional (2D) multislice method; however, due to finite slice thickness and slice gap, there is a partial-volume effect that makes it difficult to detect the net q-space signal. On the other hand, three-dimensional (3D) MRI, having the advantages of very thin slice thickness and no slice gap (contiguous slices), allows volumetric evaluation acquired in a small isotropic voxel, as compared to 2D multislice imaging. Little is known about the isotropic high-resolution 3D DWI application to q-space analysis. In this study, we have developed and implemented a high b-value 3D DWI sequence, applied q-space analysis to study the reliability of high b-value 3D DWI and obtained a microscopic analytical map with isotropic high resolution and less contamination.     

抗偏振温度变动的聚酰亚胺波导宽带耦合器

提出了一种适合于宽带光波导耦合器的抗偏振变动、抗温度变动的优化设计理论和方法。使用该理论和方法 ,在 14 90～ 16 10nm带域上 ,对氟化聚酰亚胺光波导做了 3dB耦合器的消偏振和温度依存设计。器件经三维波束传播法 (BPM)模拟运行验证 ,结果表明 ,12 0nm带宽上 ,在 - 10～ 4 0℃的环境下 ,两个正交偏振态均实现了(5 0± 0 .8) %功率输出比的良好特性     

Matryoshka Skyrmions

We construct a stable Skyrmion in 3+1$3+1$ dimensions as a sine-Gordon kink inside a domain wall within a domain wall in an O(4)$O(4)$ sigma model with hierarchical mass terms without the Skyrme term. We also find that higher dimensional Skyrmions can stably exist with a help of non-Abelian domain walls in an O(N)$O(N)$ model with hierarchical mass terms without a Skyrme term, which leads to a matryoshka structure of Skyrmions.     

Joint Function and Arthropathy Severity in Patients with Hemophilia

Background: The Arnold-Hilgartner classification is one of the most popular evaluation systems for the progression hemophilic arthropathy. A previous study reported an association between arthropathy severity and arc range of motion (ROM). However, associations between arthropathy severity and angular ROM and muscle strength remain unclear. AIM: The purpose of this study was to clarify the association between joint function and arthropathy severity in hemophilia. Methods: We studied the knee, ankle, and elbow joints of 31 patients with hemophilia (PWH). The condition of the affected joints was evaluated on the basis of the interview data, joint function measurements, and roentgenography of the affected joints. In assessment of joint function, we evaluated knee strength (flexor, extensor) and grip strength as well as the passive ROM of the elbow, knee, and ankle. During the interview, all patients were asked about the history of intra-articular bleeding over the past year and pain. Results: As arthropathy severity worsened, knee flexor strength, knee extensor strength, grip strength, and ROM (elbow flexion, elbow extension, knee flexion, knee extension, and ankle extension) significantly decreased. Even patients with mild arthropathies experienced knee extensor weakness and extension limitation. In addition, joint function of severe ankle arthropathy was significantly related to the history of intra-articular bleeding and pain. Conclusion: Our results suggest that physical therapy is necessary to improve joint function in PWH and mild or no arthropathy. Pain control and prophylactic hematological management are necessary for patients with severe arthropathy because intra-articular bleeding and pain significantly decrease joint function.     

Experimental demonstration of the time reversal Aharonov-Casher effect

We demonstrate the time reversal Aharonov-Casher (AC) effect in small arrays of mesoscopic semiconductor rings. By using an electrostatic gate we can control the spin precession rate and follow the AC phase over several interference periods. We show that we control the precession rate in two different gate voltage ranges; in the lower range the gate voltage dependence is strong and linear and in the higher range the dependence in almost an order of magnitude weaker. We also see the second harmonic of the AC interference, oscillating with half the period. We finally map the AC phase to the spin-orbit interaction parameter alpha and find it is consistent with Shubnikov-de Haas analysis.     

The first chemical conversion of l-proline to l-glutamic acid

The ruthenium tetroxide oxidation of N-acyl-l-proline esters gave the corresponding l-pyroglutamic acid derivatives in good yields with no appreciable racemization, which led to the first chemical conversion of l-proline to l-glutamic acid.     

Conformational transition of the copolymer of maleic acid and styrene in aqueous solution. II

The temperature dependence of the conformational transition from a compact to expanded-coil form of the alternating copolymer of maleic acid with styrene in aqueous 0.03M NaCl solution was studied at 15 to 40°C by pH titration, optical titration, and calorimetric measurements. The pH titration curve scarcely changed with temperature. The degree of dissociation of primary carboxyl groups in the copolymer at the midpoint of the conformational transition, determined by the optical titration, was almost independent of temperature. The standard enthalpy change of the transition at 25°C estimated from the calorimetric data was 0.36₃ kcal/mole, which may mean that the difference between the standard free energy changes of the transition at 20°C and 40°C does not exceed experimental error. The enthalpy change agrees well with the heat of transfer of benzene from the hydrophobic to the aqueous medium, and thus the compact form of the copolymer is considered to be stabilized by the hydrophobic interaction between the phenyl residues in the interior of the molecule.     

Failure Envelope Curves in Polyethylene Solids

The present work demonstrates that the failure envelope analysis can be applied for characterizing the ultimate tensile properties of polyethylene solids in which the inhomogeneous necking process is avoided. As a result, the ultimate properties are essentially identical to those of vulcanized rubbers above the glass transition temperature, suggesting that tie molecules connecting the fragmented lamellar clusters transmit the external led to the fracture site in the same manner as cross-linked rubbers do. Consideration of this crystal-network model may provide information about the molecular processes that lead to rupture. Furthermore, the present analytical method can possibly be developed for predicting rupture times when different types of tests, such as constant drawn, constant stress and constant rate of stress, are conducted.