In vivo magnetic resonance study of the histochemistry of coconut (Cocos nucifera)

Magnetic resonance imaging (MRI) and localized proton MR spectroscopy (MRS) techniques have been applied for studying different maturation processes in the histochemistry of coconut (Cocos nucifera). Images of the tender and mature coconut are characterized by protons of the aqueous solution present in the cavity and from the surrounding pulp, whereas the image of the dry coconut is from the protons of the fat present in the pulp. Localized proton MR spectra of the water present in the cavity from the tender and the mature coconut show several resonances due to different chemical constituents of coconut water, whereas typical spectra of the pulp from dry coconut reveal a profile of the hydrogens present in the saturated and unsaturated fatty acid chains. In addition, images obtained from a rancid coconut show the extent of internal damage and degradation due to fungal growth; the corresponding localized MR spectra of the coconut water reveal that several proton resonances are absent.     

Jets in tokamaks: A theoretical study

A new class of bifurcation of the momentum balance equations for a tokamak plasma is presented. The solution exhibits a monopolar localized jet of ExB flow. The jet is generated by the reduction of turbulent viscosity due to ExB velocity shear. Strong jets of localized plasma flow have been observed in tokamaks as a precursor to the development of a transport barrier region with reduced turbulent transport. The jet solution is shown to fit well with the experimental observations.     

Discrete breathers and delocalization in nonlinear disordered systems

We find exact localized time-periodic solutions with frequencies inside the linearized spectrum [intraband discrete breathers (IDBs)] in random nonlinear models using a new self-consistent method. The IDB frequencies belong to intervals between forbidden gaps generated by resonances with the linear modes, becoming fat Cantor sets in infinite systems. When localized IDBs are continued versus frequency, they delocalize and become multisite IDBs (not predicted by existing theorems), which can propagate energy. Some implications for energy relaxation in glasses are discussed.     

Synergistic Effect of Photothermal Therapy and Chemotherapy Using Camptothecin‐Conjugated Gold Nanorods

A combinatorial treatment comprising thermal therapy and chemotherapy offers synergistic effects by inducing localized heat to targeted tumor sites and simultaneously delivering anticancer drugs to minimize systemic side effects and enhance the cytotoxic effect. In this study, a novel platform is developed for combining photothermal therapy and chemotherapy using drug‐conjugated gold nanorods (GNRs). Camptothecin (CPT), a model anticancer drug, is chemically conjugated onto GNRs through hydrolytic ester bonding. Upon near‐infrared (NIR) irradiation, localized heat from GNRs in target areas starts to destroy tissues and cells via photothermal therapy, and the elevated temperature accelerates hydrolysis of ester linkage, rapidly releasing drugs for chemotherapy. This combined NIR triggered thermal therapy and chemotherapy with CPT‐functionalized GNRs (CPT‐GNRs) presents a synergistic effect that has high efficacy in in vitro tests, thus providing a robust platform for efficient cancer treatments.     

Localized Larmor frequency-guided fat and water proton MRI of the spine: a method to emphasize pathological findings.

A measurement protocol providing a correct adjustment of the irradiation frequencies for well separated fat and water images of the lumbar spine is presented. To determine accurately the Larmor frequencies of water and fat protons within the vertebral bodies, a volume selective spectrum of a volume element (13 mm)3 located in a lumbar vertebral body was acquired with the 90 degrees-180 degrees-180 degrees double spin-echo method. These Larmor frequencies are used to adjust the frequency-selective pulse of the SENEX chemical-shift imaging sequence. This procedure provides well separated fat and water images for a large field of view even in the inhomogeneous region of the vertebral column. Their clinical importance is demonstrated by localized Larmor frequency-guided (LLFG) SENEX 1H images of the lumbar spine in healthy persons of different age and in a patient with acute myeloid leukemia.     

Continuous improvement of H-mode discharge performance with progressively increasing lithium coatings in the National Spherical Torus Experiment

Lithium wall coatings have been shown to reduce recycling, improve energy confinement, and suppress edge localized modes in the National Spherical Torus Experiment. Here, we show that these effects depend continuously on the amount of predischarge lithium evaporation. We observed a nearly monotonic reduction in recycling, decrease in electron transport, and modification of the edge profiles and stability with increasing lithium. These correlations challenge basic expectations, given that even the smallest coatings exceeded that needed for a nominal thickness of the order of the implantation range.     

Objective Reduction Solutions to Higher-Order Boussinesq System in （2＋1）-Dimensions

With the help of an objective reduction approach （ORA）, abundant exact solutions of （2＋1）-dimensional higher-order Boussinesq system （including some hyperboloid function solutions, trigonometric function solutions, and a rational function solution） are obtained. It is shown that some novel soliton structures, like single linearity soliton structure, breath soliton structure, single linearity y-periodic solitary wave structure, libration dromion structure, and kink-like multisoliton structure with actual physical meaning exist in the （2＋1）-dimensional higher-order Boussinesq system.     

Ethanol-induced fatty liver in the rat examined by in vivo 1H chemical shift selective magnetic resonance imaging and localized spectroscopic methods.

In vivo 1H magnetic resonance imaging (MRI), chemical shift selective imaging (CSI), and localized (VOSY) 1H magnetic resonance spectroscopy (MRS) were used to study fatty infiltration in the livers of rats chronically fed an ethanol-containing all-liquid DeCarli-Lieber diet. Conventional total proton MRI showed a somewhat hyperintense liver for ethanol-fed rats, compared with pair-fed controls. CSI showed a dramatic increase in the fat signal intensity for ethanol-treated rats that was fairly homogeneous throughout the liver. However, CSI also showed a substantial decrease in the water signal intensity for the ethanol-treated rats compared to pair-fed control rats. 1H VOSY MR spectra also showed a 5.5-fold increase in the methylene resonance (1.3 ppm) of fat and a 50-70% decrease in the water resonance (4.8 ppm). Relative in vivo proton T1 and T2 relaxation times for the water resonance separate from the fat resonance, determined from modified VOSY experiments, were found to tend to increase and decrease, respectively, for ethanol-treated rat livers compared with controls. The decrease in hepatic water signal intensity could be accounted for by the decrease in T2 and decrease in water density due to the presence of accumulated hepatic fat (approximately 25 mg/g wet weight of liver). When ethanol was withdrawn from the chronically treated rats, fatty infiltration was observed by both CSI and VOSY spectra to revert toward control values with a half-life of 2-4 days. By day 16, however, the signal intensity for hepatic fat was still significantly higher than control levels. In vitro 1H MRS studies of chloroform-methanol extracts confirmed the 5.5-fold increase in total hepatic fat induced by the chronic ethanol treatment, and showed further that triacylglycerols were increased 7.7-fold, cholesterol was increased fourfold, and phospholipids were increased 3.3-fold, compared with liver extracts from pair-fed control rats.     

Roughness of boundary interfaces in polycrystals and its influence on the yield strength of nanocrystalline materials

The distribution in roughness of grain-boundary interfaces in polycrystals is measured metallographically. The result shows that there are high populations of localized interface areas with roughness much lower than the average in polycrystals. Effects of the roughness on the boundary sliding in nanocrystalline materials are discussed, suggesting that the sliding in the localized interface areas produces stress concentrations to cause a reduction in the yield strength of nanocrystalline materials.     

Efficient large-array k-domain parallel MRI using channel-by-channel array reduction

This article presents a method to explore the flexibility of channel reduction in k-domain parallel imaging (PI) with massive arrays to improve the computation efficiency. In PI, computation cost increases with the number of channels. For the k-domain methods requiring channel-by-channel reconstruction, this increase can be significant with massive arrays. In this article, a method for efficient k-domain PI reconstruction in large array systems is proposed. The method is based on the fact that in large arrays the channel sensitivity is localized, which allows channel reduction through channel cross correlation. The method is tested with simulated and in vivo MRI data from a 32-channel and 64-channel systems using the multicolumn multiline interpolation (MCMLI) method. Results show that the proposed algorithm can achieve similar or improved reconstruction quality with significantly reduced computation time for massive arrays with localized sensitivity.     

k-space inherited parallel acquisition (KIPA): application on dynamic magnetic resonance imaging thermometry

In this study, a novel method for dynamic parallel image acquisition and reconstruction is presented. In this method, called k-space inherited parallel acquisition (KIPA), localized reconstruction coefficients are used to achieve higher reduction factors, and lower noise and artifact levels compared to that of generalized autocalibrating partially parallel acquisition (GRAPPA) reconstruction. In KIPA, the full k-space for the first frame and the partial k-space for later frames are required to reconstruct a whole series of images. Reconstruction coefficients calculated for different segments of k-space from the first frame data set are used to estimate missing k-space lines in corresponding k-space segments of other frames. The local determination of KIPA reconstruction coefficients is essential to adjusting them according to the local signal-to-noise ratio characteristics of k-space data. The proposed algorithm is applicable to dynamic imaging with arbitrary k-space sampling trajectories. Simulations of magnetic resonance thermometry using the KIPA method with a reduction factor of 6 and using dynamic imaging studies of human subjects with reduction factors of 4 and 6 have been performed to prove the feasibility of our method and to show apparent improvement in image quality in comparison with GRAPPA for dynamic imaging.     

Fat/water quantitation and differential relaxation time measurement using chemical shift imaging technique

The use of chemical shift imaging for fat and water quantitation and differential measurement of relaxation times for the fat and water component is demonstrated using a hybrid technique. The efficacy of the imaging technique for fat and water quantitation has been tested by comparing the results of imaging to the results of volumetric measurements in phantoms with oil and water homogeneously mixed, fat extraction in ground meat of different grades, and biopsy in preliminary clinical studies. Good correlation is found between the fat and water content measured by imaging and that measured by other means except for the inability to differentiate unsaturated fat protons from water protons. Longitudinal (T1) and transverse (T2) relaxation times for water and fat are also shown to be measurable independently when fat and water signal are suppressed accordingly. The independently measured relaxation times correspond closely to those of the pure samples except that unsaturated protons give decreased water relaxation estimates.     

HL-2A 装置超声分子束注入缓解偏滤器靶板上边缘局域模热通量研究

在HL-2A 装置上优化和发展了偏滤器靶板上的红外测温系统,并利用该系统分析了高约束模放电期间边缘局域模的热沉积分布特性。在高约束模式放电期间,超声分子束注入使边缘局域模所引起的偏滤器靶板上瞬间热通量峰值下降了~60%,并伴随着边缘局域模爆发频率增加了2~3 倍,而等离子体储能仅下降了~8%。分析结果表明,大幅度的丝状结构在超声分子束注入之后得到了有效抑制,沉积到偏滤器靶板上的瞬间热通量峰值也随之下降。此外,在超声分子束注入之后偏滤器室内的热辐射损失大幅度增加,从而耗散了热输运所携带的部分能量,进一步分散了沉积到偏滤器靶板上的能量,有效地保护了偏滤器靶板。     

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在HL-2A 装置上优化和发展了偏滤器靶板上的红外测温系统,并利用该系统分析了高约束模放电期间边缘局域模的热沉积分布特性。在高约束模式放电期间,超声分子束注入使边缘局域模所引起的偏滤器靶板上瞬间热通量峰值下降了~60%,并伴随着边缘局域模爆发频率增加了2~3 倍,而等离子体储能仅下降了~8%。分析结果表明,大幅度的丝状结构在超声分子束注入之后得到了有效抑制,沉积到偏滤器靶板上的瞬间热通量峰值也随之下降。此外,在超声分子束注入之后偏滤器室内的热辐射损失大幅度增加,从而耗散了热输运所携带的部分能量,进一步分散了沉积到偏滤器靶板上的能量,有效地保护了偏滤器靶板。     

High-resolution nuclear track mapping in detailed cellular histology using CR-39 with the contact microscopy technique

In radiation cancer therapies using energetic charged particles such as proton/heavy-ion therapy and boron neutron capture therapy (BNCT), studies on radiation-induced biological response at cellular level are important because the radiation damage from energetic charged particles is highly localized along their paths and the radiation sensitivity is quite different in each cellular organelle. In such studies the information on the position of charged particle impact in biological cells is necessary. A novel method for high-resolution nuclear track mapping in detailed cellular histology has been developed. In this technique, biological specimens mounted on CR-39 plates are exposed to energetic charged particles. The irradiated samples are exposed to UV, and then etched for a short time. Both etch pits of nuclear tracks and relief for transmission UV image of the specimen can be observed on the CR-39 surface with an atomic force microscope (AFM) at about 100 nm resolution.     

Two surface plasmon resonances effects for light through the perforated metal film

Light transmission through perforated metal film has been reported and some investigations have been made into the physical origin of this phenomenon. We show that the transmission assisted with surface plasmon (SP) through a perforated metal film results from two different SP resonances effects: surface plasmon resonance due to the periodicity at the left air/metal and right metal/air interfaces and localized cavities resonance inside rectangular holes. The fields intensity is localized separately on the left and right metal-air surfaces for structure-factor-induced surface plasmon mode. And for localized cavities resonance mode, standing electromagnetic fields can also be entirely localized inside the nanohole region. The aspect ratio of the rectangular holes can affect the transmission.     

离子注入对ZnTe:O中间带光伏材料的微观结构及光学特性的影响

II-VI和III-V族高失配合金半导体是新型高效中间带太阳电池的优选材料体系,但中间带的形成及其能带调控等关键问题仍未得到有效解决.采用氧离子注入方式,在非平衡条件下对碲化锌(Zn Te)单晶材料实现了等电子掺杂,深入研究了离子注入对Zn Te:O材料的微观结构和光学特性的影响.研究表明:注入合适浓度的氧离子(2.5×1018cm-3)将会形成晶格应变,并诱导1.80 e V(导带下0.45 e V)中间带的产生;而较高浓度(2.5×1020cm-3)的氧离子会导致Zn Te注入层表面非晶化,并增强与锌空位相关的深能级(～1.6 e V)发光.时间分辨光致发光结果显示,离子注入诱导形成的中间带主要是和氧等电子陷阱束缚的局域激子发光有关,载流子衰减寿命较长(129 ps).因此,需要降低晶格紊乱度和合金无序,实现电子局域态向扩展态的转变,从而有效调控中间带能带结构.     

Empirical analysis of individual popularity and activity on an online music service system

Quantitative understanding of human behaviors supplies basic comprehension of the dynamics of many socio-economic systems. Based on the log data of an online music service system, we investigate the statistical characteristics of individual activity and popularity, and find that the distributions of both of them follow a stretched exponential form which interpolates between exponential and power law distribution. We also study the human dynamics on the online system and find that the distribution of interevent time between two consecutive listenings of music shows the fat tail feature. Besides, with the reduction of user activity the fat tail becomes more and more irregular, indicating different behavior patterns for users with diverse activities. The research results may shed some light on the in-depth understanding of collective behaviors in socio-economic systems.     

Localized Structures on Periodic Background Wave of （2＋1）-Dimensional Boiti-Leon-Pempinelli System via an Object Reduction

In this paper, we present an object reduction for nonlinear partial differential equations. As a concrete example of its applications in physical problems, this method is applied to the （2＋1）-dimensional Boiti-Leon-Pempinelli system, which has the extensive physics background, and an abundance of exact solutions is derived from some reduction equations. Based on the derived solutions, the localized structures under the periodic wave background are obtained.