Time-resolved diffuse optical tomographic imaging for the provision of both anatomical and functional information about biological tissue

We present in vivo images of near-infrared (NIR) diffuse optical tomography (DOT) of human lower legs and forearm to validate the dual functions of a time-resolved (TR) NIR DOT in clinical diagnosis, i.e., to provide anatomical and functional information simultaneously. The NIR DOT system is composed of time-correlated single-photon-counting channels, and the image reconstruction algorithm is based on the modified generalized pulsed spectral technique, which effectively incorporates the TR data with reasonable computation time. The reconstructed scattering images of both the lower legs and the forearm revealed their anatomies, in which the bones were clearly distinguished from the muscles. In the absorption images, some of the blood vessels were observable. In the functional imaging, a subject was requested to do handgripping exercise to stimulate physiological changes in the forearm tissue. The images of oxyhemoglobin, deoxyhemoglobin, and total hemoglobin concentration changes in the forearm were obtained from the differential images of the absorption at three wavelengths between the exercise and the rest states, which were reconstructed with a differential imaging scheme. These images showed increases in both blood volume and oxyhemoglobin concentration in the arteries and simultaneously showed hypoxia in the corresponding muscles. All the results have demonstrated the capability of TR NIR DOT by reconstruction of the absolute images of the scattering and the absorption with a high spatial resolution that finally provided both the anatomical and functional information inside bulky biological tissues.     

Combustion of fuel vapor-drop-air systems: Part II—Spherical flames in a vessel

The burning characteristics of fuel vapor-drop-air systems (propane-kerosene drop-air systems) have been studied using a cylindrical combustion vessel, 58 mm deep and 148 mm in diameter, with a centrally located spark gap. As in the case of burner flames reported in the previous paper, a small amount of kerosene drops added to a propane-air mixture intensities the burning process, raising the maximum pressure for an overall fuel-air ratio and shrotening the time to reach the maximum pressure from ignition. In addition, both the burning and propagating velocities of a flame for an overall fuel-air ratio are markedly accelerated by a very small amount of kerosene drops added. The combustion-promoting effects of drops are more prominent for leaner mixtures and get less prominent as the mixture becomes richer beyond the stoichimetric. An optimum value exists in the quantity of drops added to a propane-air mixture.     

Photo-electrochemical solar cells with a SnO2-liquid junction sensitized with highly concentrated dyes

The sensitization of a SnO₂-liquid junction cell with highly concentrated dyes was investigated. The dyes used were Crystal Violet, Methyl Violet B, Malachite Green, Pararosaniline, and Rhodamine B. Anomalous or positive photovoltages were obtained in the system when Fe(CN) ₆ ^3– was added. The performance of the photovoltaic cells showed an open-circuit photovoltage,V _oc, of 175 mV, a short-circuit photocurrent,I _sc, of 12 A, and a fill factor of 0.42. The action spectra resembled the absorption spectra of the aggregated dyes. A D-D mechanism is introduced to explain the anomaly of the photovoltage of the SnO₂ electrode sensitized with the dyes. This behaviour is relevant to the practical usage of such photo-electrochemical cells and merits further investigation.     

Note: Unshielded bilateral magnetoencephalography system using two-dimensional gradiometers

Magnetoencephalography (MEG) noninvasively measures neuronal activity with high temporal resolution. The aim of this study was to develop a new type of MEG system that can measure bilateral MEG waveforms without a magnetically shielded room, which is an obstacle to reducing both the cost and size of an MEG system. An unshielded bilateral MEG system was developed using four two-dimensional (2D) gradiometers and two symmetric cryostats. The 2D gradiometer, which is based on a low-T(c) superconducting quantum interference device and wire-wound pickup coil detects a magnetic-field gradient in two orthogonal directions, or ?/?x(?(2)B(z)/?z(2)), and reduces environmental magnetic-field noise by more than 50 dB. The cryostats can be symmetrically positioned in three directions: vertical, horizontal, and rotational. This makes it possible to detect bilateral neuronal activity in the cerebral cortex simultaneously. Bilateral auditory-evoked fields (AEF) of 18 elderly subjects were measured in an unshielded hospital environment using the MEG system. As a result, both the ipsilateral and the contralateral AEF component N100m, which is the magnetic counterpart of electric N100 in electroencephalography and appears about 100 ms after the onset of an auditory stimulus, were successfully detected for all the subjects. Moreover, the ipsilateral P50m and the contralateral P50m were also detected for 12 (67%) and 16 (89%) subjects, respectively. Experimental results demonstrate that the unshielded bilateral MEG system can detect MEG waveforms, which are associated with brain dysfunction such as epilepsy, Alzheimer's disease, and Down syndrome.     

Characterization of Aspergillus oryzae glycoside hydrolase family 43 β-xylosidase expressed in Escherichia coli

This is the first report of glycoside hydrolase family 43 β-xylosidase from Aspergillus oryzae. To characterize this enzyme, the recombinant enzyme was expressed in Escherichia coli. Unlike known β-xylosidases from fungal origins, the enzyme did not show substrate ambiguity and was stable at alkaline pH.     

不同路面条件下轮胎牵引性能数值模拟分析

车辆行驶路面多种多样,如干路面、湿路面、冰路面、雪路面和土路面等.轮胎是车辆与行驶路面之间的唯一接触点,而轮胎牵引性能随着不同路面条件发生相应的变化.轮胎牵引性能是决定车辆安全性能的关键因素,可通过数值模拟的方式研究不同路面条件下轮胎牵引力的变化情况.例如隐-显式有限元方法可用于提高轮胎在干路面条件下的性能,如图1所示,轮胎的预测力和力矩与试验结果吻合.在预测中,有限元分析方法对研究较大侧偏角情况是非常有帮助的.尽管希望对轮胎在其它路面条件下的不同性能进行预测,但目前在数值模拟方面的研究很少,其中一个难点是轮胎与路面的接触问题,不同类型的接触面为研究工作带来一定难度.近几年,解决了流体/结构体相互作用问题的数值模拟方法被用于分析不同路面条件下轮胎的牵引性能.     

Comparison of the phytohaemagglutinin from red kidney bean (Phaseolus vulgaris) purified by different affinity chromatography

Affinity chromatography (AC) on Affi-Gel blue gel column and thyroglobulin (Tg)-Sepharose 4B column, respectively, were compared for their efficiency in purifying phytohaemagglutinin (PHA) from red kidney beans (Phaseolus vulgaris). Considering the purity and haemagglutinating activity of the obtained samples, Affi-Gel blue gel exhibited less affinity for PHA than Tg-Sepharose matrix. Affi-Gel blue purified sample showed multiple bands in SDS-PAGE gel, which further confirmed that Affi-Gel blue bound non-PHA proteins as well as PHA. PHA purified by one-step Tg-Sepharose column gave significantly (p < 0.05) higher purity (0.75 ± 0.13 mg PHA/mg lyophilized powder) than the sample purified by two-step (Affi-Gel blue first and then Tg-Sepharose) purification (0.62 ± 0.20 mg PHA/mg lyophilized powder). Circular dichroism (CD) spectra showed that the sample purified by one-step Tg-Sepharose column had similar secondary structures with the sample purified by two-step purification. Thus, one-step Tg-Sepharose purification was effective and time-saving for the preparation of PHA and a promising substitute for the two-step purification method.     

Optimization of antioxidant peptide production from grass carp sarcoplasmic protein using response surface methodology

The sarcoplasmic protein was extracted from the muscle of grass carp, a Chinese freshwater carp, and was hydrolyzed with five proteases to produce antioxidant peptides. Papain hydrolysate was found to have the greatest activity against lipid peroxidation. Response surface methodology (RSM) was applied to optimize the hydrolysis conditions (including enzyme to substrate ratio, time and temperature). The minimum EC₅₀ value (317.25 μg/mL) which signified the maximum antioxidant activity was obtained at an enzyme to substrate ratio of 0.79%, an incubation time of 5.69 h and an incubation temperature of 52.15 °C, which was in agreement with the predicted value (313.99 μg/mL) estimated by RSM within a 95% confidence interval. Also, it was found that moderate denaturation of the sarcoplasmic protein and a modest increase in the degree of hydrolysis promoted the antioxidant activities of the hydrolysates. Oligopeptides (< 3 kDa) contributed more to the antioxidant activity than polypeptides.