Discovery of NKT cells and development of NKT cell-targeted anti-tumor immunotherapy

Natural Killer T (NKT) cells are unique lymphocytes characterized by their expression of a single invariant antigen receptor encoded by Vα14Jα18 in mice and Vα24Jα18 in humans, which recognizes glycolipid antigens in association with the monomorphic CD1d molecule. NKT cells mediate adjuvant activity to activate both CD8T cells to kill MHC-positive tumor cells and NK cells to eliminate MHC-negative tumor at the same time in patients, resulting in the complete eradication of tumors without relapse. Therefore, the NKT cell-targeted therapy can be applied to any type of tumor and also to anyone individual, regardless of HLA type.Phase IIa clinical trials on advanced lung cancers and head and neck tumors have been completed and showed significantly prolonged median survival times with only the primary treatment. Another potential treatment option for the future is to use induced pluripotent stem cell (iPS)-derived NKT cells, which induced adjuvant effects on anti-tumor responses, inhibiting in vivo tumor growth in a mouse model.     

A volume‐exclusion normalization procedure for quantitative Raman confocal microspectroscopy of immersed samples applied to human embryonic stem cells

Raman microspectroscopy is a quantitative instrumental method with considerable promise for the nondestructive analysis of living biological samples. Amongst samples of particular interest are human embryonic stem cells because of their therapeutic potential and because examination using Raman microspectroscopy does not appear to adversely affect this potential. However, it can be difficult to compare different spectra obtained with this technique and to quantify the native cellular constituents of such samples because their characteristic dimensions are difficult to establish or may vary from point to point. We present here a method to normalize spectra and estimate sample thicknesses based on a reference component present in the basal cell culture medium when we perform spectroscopy on colonies of living cells. Because more basal medium is displaced from the sampling volume as the cell layer increases in thickness, and because this component is present in the medium but excluded from cells, a concomitant decline therefore occurs in the intensity of the Raman scattering from the reference component. This permits comparisons between samples because their spectra can be scaled in inverse relation to their excluded volumes. Furthermore, estimations of sample thicknesses can also be obtained based on the same concept. Thus, the absolute quantification of cellular components becomes possible because cell sample volumes can be determined. Although applied to human embryonic stem cells, the approach is sufficiently general to be adapted for use with other samples. Copyright © 2011 John Wiley & Sons, Ltd.     

Evidence of marked glycogen variations in the characteristic Raman signatures of human embryonic stem cells

Human embryonic stem cells (hESCs) have typical Raman signatures, but specific factors that contribute to variations in these signatures have not been reported to date. Furthermore, variations due to the passaging that is necessary for hESC culture maintenance could potentially distort these signatures. It is therefore important to characterize the impact of these culture manipulations on the Raman spectra to gain a better understanding of the origins and nature of their variations. Here we report on the Raman microspectroscopy of hESCs samples from maintenance cultures, complemented with periodic acid Schiff (PAS, carbohydrates) and 4′‐6‐diamidino‐2‐phenlyindol (DAPI, nuclei) staining. The component predominantly responsible for variations between spectra was spectrally identified as glycogen. Variations in the Raman map of the 480 cm⁻¹ glycogen marker band corresponded with those of a PAS stain of the same sample area. The 785‐nm Raman microspectra of hESC cultures examined daily after passaging showed that the same nonrandom spectral variances occurred at all time points after passaging. The pattern of these variances was identified as being due to glycogen spectral components. Our results help validate the previously observed spectral signatures of hESCs and further delineate and characterize the variations that can be expected in these signatures under normal maintenance culture conditions, and aid distinguishing them from those corresponding to differentiation, thus providing a benchmark for future studies. Copyright © 2010 John Wiley & Sons, Ltd.     

Raman microspectroscopic evidence that dry‐fixing preserves the temporal pattern of non‐specific differentiation in live human embryonic stem cells

Raman microspectroscopy allows the classification of populations of human embryonic stem cells (hESCs) in different stages of differentiation based on the relative intensities of certain amino acid and nucleic acid bands. Here, we report the results of a comparative study of the Raman spectra of live cells versus cells killed and fixed by rapid desiccation, focusing on the ratio of intensities at 757 cm⁻¹ (tryptophan) and 784 cm⁻¹ (DNA and RNA). We observe that the same temporal pattern emerges over a 3‐week time course in both sample types. This suggests that prolonged observations of dry‐fixed cells can yield high signal‐to‐noise chemical images that cannot be obtained from colonies of living cells where the time scale of significant biological changes are comparable to the time scale of the measurement. This permits, for example, comparison of the spatial distributions of cells at different stages of differentiation within the same colonies. Copyright © 2010 John Wiley & Sons, Ltd.     

Raman spectroscopy and CARS microscopy of stem cells and their derivatives

The characterisation of stem cells is of vital importance to regenerative medicine. Failure to separate out all stem cells from differentiated cells before therapies can result in teratomas—tumours of multiple cell types. Typically, characterisation is performed in a destructive manner with fluorescent assays. A truly non‐invasive method of characterisation would be a major breakthrough in stem cell‐based therapies. Raman spectroscopy has revealed that DNA and RNA levels drop when a stem cell differentiates into other cell types, which we link to a change in the relative sizes of the nucleus and cytoplasm. We also used Raman spectroscopy to investigate the biochemistry within an early embryo, or blastocyst, which differs greatly from colonies of embryonic stem cells. Certain cell types that differentiate from stem cells can be identified by directly imaging the biochemistry with CARS microscopy; examples presented are hydroxyapatite—a precursor to bone, and lipids in adipocytes. Copyright © 2011 John Wiley & Sons, Ltd.     

A novel three-dimensional system to study interactions between endothelial cells and neural cells of the developing central nervous system

Background  

During angiogenesis in the developing central nervous system (CNS), endothelial cells (EC) detach from blood vessels growing on the brain surface, and migrate into the expanding brain parenchyma. Brain angiogenesis is regulated by growth factors and extracellular matrix (ECM) proteins secreted by cells of the developing CNS. In addition, recent evidence suggests that EC play an important role in establishing the neural stem cell (NSC) niche. Therefore, two-way communication between EC and neural cells is of fundamental importance in the developing CNS. To study the interactions between brain EC and neural cells of the developing CNS, a novel three-dimensional (3-D) murine co-culture system was developed. Fluorescent-labelled brain EC were seeded onto neurospheres; floating cellular aggregates that contain NSC/neural precursor cells (NPC) and smaller numbers of differentiated cells. Using this system, brain EC attachment, survival and migration into neurospheres was evaluated and the role of integrins in mediating the early adhesive events addressed.     

Comparison of light-induced degradation and regeneration in P-type monocrystalline full aluminum back surface field and passivated emitter rear cells

This paper reports on a systematic and quantitative assessment of light induced degradation (LID) and regeneration in full Al-BSF and passivated emitter rear contact cells (PERC) along with the fundamental understanding of the difference between the two. After LID, PERC cells showed a much greater loss in cell efficiency than full Al-BSF cells (∼0.9% vs ∼0.6%) because the degradation in bulk lifetime also erodes the benefit of superior BSRV in PERC cells. Three main regeneration conditions involving the combination of heat and light (75 °C/1 Sun/48 h, 130 °C/2 Suns/1.5 h and 200 °C/3 Suns/30 s) were implemented to eliminate LID loss due to BO defects. Low temperature/long time (75 °C/48 h) and high temperature/short time (200 °C/30s) regeneration process was unable to reach 100% stabilization. The intermediate temperature/time (130 °C/1.5 h) generation achieved nearly full recovery and stabilization (over 99%) for both full Al-BSF and PERC cells. We discussed the effect of temperature, time and suns in regeneration mechanism for two cells.     

Light‐induced degradation and regeneration of multicrystalline silicon Al‐BSF and PERC solar cells

Light‐induced degradation (LID) is a well‐known problem faced by p‐type Czochralski (Cz) monocrystalline silicon (mono‐Si) wafer solar cells. In mono‐Si material, the physical mechanism has been traced to the formation of recombination active boron‐oxygen (B–O) complexes, which can be permanently deactivated through a regeneration process. In recent years, LID has also been identified to be a significant problem for multicrystalline silicon (multi‐Si) wafer solar cells, but the exact physical mechanism is still unknown. In this work, we study the effect of LID in two different solar cell structures, aluminium back‐surface‐field (Al‐BSF) and aluminium local back‐surface‐field (Al‐LBSF or PERC (passivated emitter and rear cell)) multi‐Si solar cells. The large‐area (156 mm × 156 mm) multi‐Si solar cells are light soaked under constant 1‐sun illumination at elevated temperatures of 90 °C. Our study shows that, in general, PERC multi‐Si solar cells degrade faster and to a greater extent than Al‐BSF multi‐Si solar cells. The total degradation and regeneration can occur within ～320 hours for PERC cells and within ～200 hours for Al‐BSF cells, which is much faster than the timescales previously reported for PERC cells. An important finding of this work is that Al‐BSF solar cells can also achieve almost complete regeneration, which has not been reported before. The maximum degradation in Al‐BSF cells is shown to reduce from 2% (relative) to an average of 1.5% (relative) with heavier phosphorus diffusion.     

The biological characteristics of different generation mesenchymal stem cells cultured in vitro and cocultured with vascular scaffold

Mesenchymal stem cells (MSCs) were used widely as seed cells in tissue engineering blood vessel construction. However, the biological characteristics difference of different generation MSCs in vitro culture is unknown, which laid a foundation for appropriate generation seeded cells selection for tissue engineering blood vessel construction. In this report, MSCs were isolated from SD rat bone marrow and identified by flow cytometry; cell growth curve test, cell surface antigen expression rate detection, cryopreservation resuscitation rate test, CD31 expression rate test, cell cycle analysis, and adhesion difference on vascular scaffold test were performed. The research results indicated that the MSCs shape was spindle and uniform with vigorous growth. CD105 and CD90 factor expression rate reached 82.5 and 84.9%, respectively, and the expression rate of CD45 was only 7.3%. The proliferation capacity of the fourth generation MSCs were more exuberant, with proliferation index as 20.3%; the cell proliferation index of the eighth generation decreased to only 9.1%. The cryopreservation resuscitation rate of the second generation and fourth generation MSCs were both higher than 80%, and the cryopreservation resuscitation rate of the eighth generation MSCs was only about 60%. After the induction for 5 days, MSCs had weak CD31 expression, and with the prolonged induction time, expression increased. All generation MSCs expressed CD31 after being induced for 10 days; however, the CD31 positive expression rate of the second generation, fourth generation, and sixth generation MSCs had significant difference with the eighth generation MSCs. Adhesion rate of MSCs before sixth generation was around 40%, but the adhesion rate of eighth generation MSCs was only about 27%. In all, biological characteristics of different generation MSCs existed certain differences, and especially the eighth generation MSCs aged seriously, whose cell activity decreased significantly. The researchers believed that the MSCs before the sixth generation can maintain excellent properties of MSCs, and can be used as seed cells for vascular tissue engineering.     

Enhanced Protein Adsorption,Cell Attachment,and Neural Differentiation with the Help of Amine Functionalized Polycaprolactone Scaffolds

Today, neurodegenerative diseases are very common among people. As a result, researchers are investigating methods for treatment of these diseases. One therapeutic approach is differentiating stem cells into neural cells to replace damaged areas of the brain. Cell attachment is the first, necessary step for the process of differentiation. Hence, we tried to enhance cell adhesion and proliferation of bone marrow stem cells on poly(?-caprolactone) (PCL) scaffolds through modifying this substrate with amine functional groups. The presence of amine groups was confirmed by Fourier transform infrared spectrometry (FTIR). Protein adsorption was measured at 280 nm via UV-spectrometry. The proliferation of differentiated neurons was assessed by 3-(4,5-Dimethylthiazol-2-Yl)-2,5-Diphenyltetrazolium Bromide (a dye) and cresyl violet staining. Finally, the morphology of differentiated neurons was shown by scanning electron microscopy (SEM). Results showed that amine modification of PCL scaffolds enhanced protein absorption and, consequently, cell adhesion and proliferation.     

The role of stacking faults for the formation of shunts during potential‐induced degradation of crystalline Si solar cells

Mono‐ and multicrystalline solar cells have been stressed by potential‐induced degradation (PID). Cell pieces with PID‐shunts are imaged by SEM using the EBIC technique in plan view as well as after FIB cross‐section preparation. A linear shaped signature is found in plan‐view EBIC images at every potential‐induced shunt position on both mono‐ and multicrystalline solar cells. Cross‐sectional SEM and TEM images reveal stacking faults in a {111} plane. Combined TEM/EDX measurements show that the stacking faults are strongly decorated with sodium. Thus, the electric conductivity of stacking faults is assumed to arise under the influence of sodium ion movement through a high electric field across the SiN_x anti‐reflective layer, resulting in PID. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Efficacy of magnetic resonance diffusion tensor imaging and three-dimensional fiber tractography in the detection of clinical manifestations of central nervous system lupus

Systemic lupus erythematosus (SLE) is an autoimmune disease frequently associated with neuropsychiatric manifestations. No follow-up case report has characterized white matter alterations in patients with neuropsychiatric lupus erythematosus (NPSLE) before and after treatment. In this study, a 16-year-old NPSLE patient with severe neuropsychological symptoms was treated with steroid pulse therapy, and was scanned with conventional magnetic resonance (MR) and diffusion tensor imaging (DTI) at onset and 17 months after treatment. Conventional MR images showed diffuse brain atrophy and focal vasogenic edema in the putamen, but they did not reveal abnormalities in the corpus callosum. Region-of-interest analysis of DTI images showed that fractional anisotropy and fiber tracts increased significantly, while axial diffusivity, radial, and mean diffusivity decreased significantly in the corpus callosum after treatment. The results indicated that the vasogenic edema was present in the corpus callosum at onset and was significantly reduced after treatment. These changes were generally compatible with the patient’s clinical manifestations. Hence, we concluded that MR-DTI and fiber tractography are helpful to reveal the relationship between white matter alterations and neurological dysfunctions in NPSLE patients.     

Experimental and predictive study on the performance and energy consumption characteristics for the regeneration of activated alumina assisted by ultrasound

Activated alumina used in dehumidification should be regenerated at more than 110 °C temperature, resulting in excessive energy consumption. Comparative experiments were conducted to study the feasibility and performance of ultrasonic assisted regeneration so as to lower the regeneration temperature and raise the efficiency. The mean regeneration speed, regeneration degree, and enhanced rate were used to evaluate the contribution of ultrasound in regeneration. The effective moisture diffusivity and desorption apparent activation energy were calculated by theoretical models, revealed the enhanced mechanism caused by ultrasound. Also, we proposed some specific indexes such as unit energy consumption and energy-saving ratio to assess the energy-saving characteristics of this process. The unit energy consumption was predicted by artificial neural network (ANN), and the recovered moisture adsorption of activated alumina was measured by the dynamic adsorption test. Our analysis illustrates that the introduction of power ultrasound in the process of regeneration can reduce the unit energy consumption and improve the recovered moisture adsorption, the unit energy consumption was decreased by 68.69% and the recovered moisture adsorption was improved by 16.7% under 180 W power ultrasound compared with non-ultrasonic assisted regeneration at 70 °C when initial moisture adsorption was 30%. Meanwhile, an optimal regeneration condition around the turning point could be obtained according to the predictive results of ANN, which can minimize the unit energy consumption. Moreover, it was found that a larger specific surface area of activated alumina induced by ultrasound contributed to a better recovered moisture adsorption.     

Thermal modeling and the optimized design of metal plate cooling systems for single concentrator solar cells

A metal plate cooling model for 400× single concentrator solar cells was established.The effects of the thickness and the radius of the metal plate,and the air environment on the temperature of the solar cells were analyzed in detail.It is shown that the temperature of the solar cells decreased sharply at the beginning,with the increase in the thickness of the metal plate,and then changed more smoothly.When the radius of the metal plate was 4 cm and the thickness increased to 2 mm or thicker,the temperature of the solar cell basically stabilized at about 53 C.Increasing the radius of the metal plate and the convective transfer coefficient made the temperature of the solar cell decrease remarkably.The effects of Al and Cu as the metal plate material on cooling were analyzed contrastively,and demonstrated the superiority of Al material for the cooling system.Furthermore,considering cost reduction,space holding and the stress of the system,we optimized the structural design of the metal plate.The simulated results can be referred to the design of the structure for the metal plate.Finally,a method to devise the structure of the metal plate for single concentrator solar cells was given.     

飞机跑道胶痕的自动识别系统设计与实现

为了减轻机场跑道除胶工作人员的劳动强度,提高除胶工作效率,文章提出了一种基于机器视觉的胶痕自动查找和识别方法,设计了基于ARM单片机控制的图像无线采集和基于PC机控制的图像接收、图像预处理和图像识别系统。文章通过分析预处理后的数据特点,确定了基于细胞神经网络算法的胶痕识别算法,然后在MATLAB仿真环境下确定了该算法的最优模型和参数,最后在Visual C++ 6.0环境下完成了该算法的程序编译,调试并完成了对胶痕的自动识别过程。理论仿真和程序测试的结果证明了文章提出的方法在胶痕自动识别系统中的可行性,也为机场特种设备的无人化和智能化提供了参考。