Coherent motion sensitivity predicts individual differences in subtraction

Recent findings suggest deficits in coherent motion sensitivity, an index of visual dorsal stream functioning, in children with poor mathematical skills or dyscalculia, a specific learning disability in mathematics. We extended these data using a longitudinal design to unravel whether visual dorsal stream functioning is able to predict individual differences in subsequent specific mathematical skills, i.e., single-digit subtraction and multiplication. We measured children's sensitivity to coherent motion in kindergarten (mean age: 5 years 8 months) and evaluated their subtraction and multiplication skills in third grade (mean age 8 years 3 months). Findings revealed an association between subtraction but not multiplication performance and coherent motion sensitivity. This association remained significant even when intellectual ability and reading ability were additionally controlled for. Subtractions are typically solved by means of quantity-based procedural strategies, which reliably recruit the intraparietal sulcus. Against the background of a neural overlap between the intraparietal sulcus and visual dorsal stream functioning, we hypothesize that low-level visuospatial mechanisms might set constraints on the development of quantity representations, which are used during calculation, particularly in subtraction.     

HPLC-ELSD法同时测定知母药材中5种成分的含量

目的采用高效液相色谱-蒸发光散射检测方法(HPLC-ELSD)建立同时测定知母药材中新芒果苷、芒果苷、知母皂苷BⅡ、宝藿苷Ⅰ及知母皂苷AⅢ的含量测定方法。方法采用Agilent poroshell 120 EC-C₁₈柱,流动相采用乙腈-0.2%醋酸水系统,梯度洗脱;柱温为30℃,流速为0.7 ml/min;蒸发光散射检测器以氮气为雾化气,雾化气温度为40℃,漂移管温度为90℃,氮气体积流量为2.0 L/min;进样量为20μl。结果 5种成分均能达到基线分离,新芒果苷24.1～386μg/ml(r=0.999 3)、芒果苷23.2～371μg/ml(r=0.998 6)、知母皂苷BⅡ54.2～867.2μg/ml(r=0.995 6)、宝藿苷Ⅰ5.3～84.8μg/ml(r=0.996 8)、知母皂苷AⅢ10～160μg/ml(r=0.998 9)的浓度范围内呈现良好的线性关系。5种成分的平均加样回收率在101.8%～105.0%之间,重复性RSD小于2.4%,知母药材中上述5种成分含量分别为1.62%、0.82%、7.36%、0.07%、0.34%。结论该方法...     

Infection dynamics and virus-induced apoptosis in cell culture-based influenza vaccine production—Flow cytometry and mathematical modeling

Cell culture-based influenza vaccine manufacturing is of growing importance. Depending on virus strains, differences in infection dynamics, virus-induced apoptosis, cell lysis and virus yields are observed. Comparatively little is known concerning details of virus–host cell interaction on a cellular level and virus spreading in a population of cells in bioreactors. In this study, the infection of MDCK cells with different influenza A virus strains in lab-scale microcarrier culture was investigated by flow cytometry. Together with the infection status of cells, virus-induced apoptosis was monitored. A mathematical model has been formulated to describe changes in the concentration of uninfected and infected adherent cells, dynamics of virus particle release (infectious virions, hemagglutinin content), and the time course of the percentage composition of the cell population.     

Light scattering in artificial fog and simulated with light scattering filter

Disability glare, affecting e.g. road safety at night, may result either from intraocular light scattering or from external conditions such as fog. Measurements were made of light scattering in fog and compared with intraocular straylight data for normal eyes and eyes with simulated cataract. All measurements were made with a direct compensation flicker method. To estimate light scattering levels in fog, straylight measurements were carried in a fog chamber for different densities of fog. Density was characterized by the meteorological term visibility V and ranged from 7 to 25. Test distance for measurements in the fog was constant at 5 m. Cataract eye conditions were simulated by placing a light scattering polymer dispersed liquid crystal (PDLC) filter with scatterers of submicron size in front of the normal eye. All measurements were made using each of three broad-band color stimuli – red, green and blue (produced either with LEDs or a color CRT monitor). Differences were found in both the level and the spectral characteristics of scattering under the different conditions. The measured values of the straylight parameter, s , in artificial fog showed no noticeable spectral dependence at any visibility range. Increasing the visibility range caused an exponential decrease in the straylight. Intraocular straylight measured with the clear eye showed an increase at the red and blue ends of the spectrum as compared to the green. Straylight measured using PDLC plates with different transparency levels showed a spectral dependence which decreased with wavelength. The scattering introduced by the PDLC plate therefore failed to give a valid simulation of cataract and fog conditions for polychromatic stimuli, due to its erroneous spectral dependence.     

Design and In-line Raman Spectroscopic Monitoring of a Protein Batch Crystallization Process

Raman spectroscopy was used to design and monitor a lysozyme protein batch crystallization process in a lab scale study to facilitate the design of a pharmaceutical protein manufacturing process. A D-optimal design that consisted of 18 experiments was performed to elucidate the effect of temperature, concentration of the precipitating agent, time of crystallization, and possible interactions between these three factors on the Raman scattering changes. A polynomial mathematical model was calculated relating the scattering of the lysozyme solutions measured at individual Raman shifts to the significant factors obtained in the previous crystallization experiment. The 2,940-cm⁻¹ band provided the highest correlation values indicative of small prediction errors and good predictive ability for the crystallization model. Raman scattering signals obtained during the experiments were used as input to obtain a response surface for the factors studied and elucidate the relationship between the crystallization process conditions and the crystals obtained. The main factors affecting the crystallization process were the sodium chloride concentration and temperature.     

Light scattering in rat neocortical slices differs during spreading depression and ischemia

Spreading depression (SD) and ischemia are different pathophysiological events but have similar characteristics. This study investigated whether similarity exists in the light scattering (LS) properties during SD and ischemia in rat neocortical slices. SD was induced by injection of K(+) while ischemia was simulated by removing oxygen and glucose. LS was simultaneously recorded with changes in extracellular direct current (DC) potential and extracellular space (ECS) volume. LS was measured using a photon counting fiber optic system and the ECS volume change was determined by measuring the ECS concentration of tetramethylammonium (TMA(+)). Slices maintained in normal artificial cerebrospinal fluid (ACSF) showed a consistent LS increase during SD, but exhibited two different LS behaviors during 6 min of ischemia. In eight slices, LS decreased and remained so until the end of the ischemic challenge. In another 10 slices, LS diminished initially but, after 2 min, suddenly reversed sign, accompanied by a rapid negative shift in extracellular DC potential. When 50 or 91% of Cl(-) in the ACSF was replaced by membrane-permeable propionate, LS retained its increase during SD, but always showed the sudden LS reversal during ischemia. In contrast, when Cl(-) was substituted with membrane-impermeant methylsulfate, the SD-induced LS increase was replaced by an LS decrease, and the sudden LS reversal during ischemia was absent. While the LS signal showed different characteristics during SD and ischemia, the DC potential always presented negative shifts and the ECS volume always exhibited similar decreases. These results suggest that the polarity of the LS signal is determined by the competition of at least two factors: cell swelling and anion influx.     

Mapping dynamic concentration profiles with micrometric resolution near an active microscopic surface by confocal resonance Raman microscopy. Application to diffusion near ultramicroelectrodes: first direct evidence for a conproportionation reaction

Confocal Raman microspectroscopy is a very efficient means for probing the molecular composition of micrometric-sized samples. Its coupling with Raman resonance spectroscopy allows the specific tracking of very dilute species by considerably enhancing its Raman bands. Thus, spatially resolved information on the chemical composition of diffusion layers, which build up spontaneously near an active surface placed in a solution, can be obtained with a micrometric resolution. In this work, the applicability of the method for imaging diffusional transport towards ultramicroelectrodes with a micrometric resolution is examined. The efficiency and versatility of confocal resonance Raman microspectroscopy have been tested by probing the composition of the two different diffusion layers which build up in the vicinity of an ultramicroelectrode during the reduction of tetracyanoquinodimethane (TCNQ) on its first or second electrochemical wave. Besides the establishment of the method, this work affords the first direct experimental evidence of the existence and role of conproportionation reactions, which take place on the second reduction wave of EE electrochemical systems. In both cases, the concentration profiles of the radical anion TCNQ^? agree extremely well with the theoretical predictions.     

光敏性双亲共聚物在水溶液中的胶束化行为

通过ε-己内酯改性丙烯酸酯(FAa，n=1～4)与肉桂酰氯间的酰化反应合成了一系列光敏性大单体(FAaC)，与甲基丙烯酸(MAA)在溶液中进行自由基聚合，制备了具有光敏性的双素无规共聚物(PMFAaC)。将PMFAaC在选择性溶剂中进行自组装，可以形成纳米结构的聚合物。用动态激光光散射(DLS)研究了聚合物胶束的溶液行为，同时考察了单体含量、聚合物终浓度、聚合物侧链长、pH值、离子强度及温度等因素对胶束粒径的影响。实验结果表明，PMFAaC在选择性溶剂中可自组装成胶束，其粒径及其分布对单体含量、聚合物终浓度、聚合物侧链长、pH值、离子强度等有一定的依赖性，而对温度无依赖性。进一步用紫外光使肉桂酰基发生交联反应。从而制备得到核交联且稳定的纳米胶束。用DIS表征发现交联后的胶束粒径较交联前的小。     

Solid-state transformation of a leukotriene antagonist

SK&F 104353, a potent leukotriene antagonist, exists in two physically distinct species as a disodium salt. Type I melts with decomposition, showing a single endotherm in the region of 250–270°C in differential scanning calorimetry (DSC) thermograms, as well as exhibiting a weak powder X-ray diffraction (XRD) pattern. Type II contains a single DSC melting endotherm in the same region, but in contrast has additional, smaller endotherms in the region of 70–85°C; the new transitions remain upon cooling and reheating. The powder XRD pattern of II is very similar to that of I with respect to peak positions, but II's bands are sharper, suggestive of increased crystallinity. Types I and II can also be distinguished using solution calorimetry, manifesting different heats of solution in an ethanol/water mixture. Apparent irreversible conversion of I to II can readily occur, and has a significant impact with respect to physical stability of potential suspension aerosol formulations. The results are explained in terms of a solid-state transformation, i.e., from a metastable, partially amorphous form of low crystallinity (I) to a similar but more physically stable form of higher crystallinity (II); the conversion is facilitated by the presence of water, although true ‘hydration’ is not involved. Temperature-dependent Raman spectroscopy has been applied to characterize the transformation in more detail. The unusual solid-state behavior of this compound may reflect more general structural characteristics of leukotriene antagonists.