Structural modifications of zinc phthalocyanine thin films for organic photovoltaic applications

Zinc phthalocyanine (ZnPc) thin films are vacuum-evaporated on bare indium-tin-oxide (ITO) coated glass by varying substrate temperature and growth rate. The samples are characterized by atomic force microscopy, x-ray diffraction, and infrared spectroscopy. The temperature does not play a clear role in the crystalline growth of ZnPc possibly due to the significant structural defects on ITO surface, while it strongly influences the surface morphology and molecular alignment. The relationships between growth characteristics and performances of photovoltaics with planar heterojunction are discussed in detail. Increasing temperature or growth rate leads to a rougher surface morphology, which enables more donor/accepter interface area for photocurrent generation. Moreover, at elevated temperature, more molecules adopt standing-up geometry, resulting in a reduction in overall efficiency. The results imply that low-temperature process in order to control the molecular alignment is preferred for efficient organic photovoltaics. By simply increasing the growth rate of ZnPc up to 0.40 Å/s at room temperature, ZnPc/C60 planar heterojunction shows an efficiency of 1.66, compared to 1.24 for the cell when ZnPc is prepared at 0.10 Å/s. © 2012 American Institute of Physics

"Phase separation of co-evaporated ZnPc:C

We demonstrate phase separation of co-evaporated zinc phthalocyanine (ZnPc) and fullerene (C 60) for efficient organic photovoltaic cells. With introducing a poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) film and a crystalline copper iodide film on indium tin oxide, 20-nm-thick ZnPc film adopts a lying-down crystalline geometry with grain sizes of about 50 nm. This surface distributed with strong interaction areas and weak interaction areas enables the selective growth of ZnPc and C 60 molecules during following co-evaporation, which not only results in a phase separation but also improve the crystalline growth of C 60. This blend film greatly enhances the efficiencies in photocurrent generation and carrier transport, resulting in a high power conversion efficiency of 4.56 under 1 sun. © 2012 American Institute of Physics

Test of High Temperature Superconducting REBCO Coil Assembly for a Multi-Frequency ECR Ion Source

Chong T.H., Fukuda M., Yorita T., et al. Test of High Temperature Superconducting REBCO Coil Assembly for a Multi-Frequency ECR Ion Source. IEEE Transactions on Applied Superconductivity 34, 1 (2024); https://doi.org/10.1109/TASC.2024.3360935.High temperature superconducting REBCO tape has the characteristic of maintaining high critical current density under strong external magnetic field, which makes it an ideal material for the construction of air-core electromagnets of accelerator and electron cyclotron resonance (ECR) ion source. In Research Center for Nuclear Physics, Osaka University, a non-insulated air-cored REBCO coil assembly has been constructed. This coil assebmly consists of three circular REBCO solenoid and six racetrack REBCO coil. This coil assembly will be used as an electromagnet of a multi-frequency ECR ion source, and is also developed as a key technology development of an air-core cyclotron. The magnetic field of this ion source are designed, and 77 K performance tests of the assembly are carried out in order to examine the capability of REBCO coils of inducing magnetic field under external field. In this work, the test results and the magnetic field designed for the ECR ion source will be presented and discussed

Noninvasive prediction of shunt operation outcome in idiopathic normal pressure hydrocephalus

Idiopathic normal pressure hydrocephalus (iNPH) is a syndrome characterized by gait disturbance, cognitive deterioration and urinary incontinence in elderly individuals. These symptoms can be improved by shunt operation in some but not all patients. Therefore, discovering predictive factors for the surgical outcome is of great clinical importance. We used normalized power variance (NPV) of electroencephalography (EEG) waves, a sensitive measure of the instability of cortical electrical activity, and found significantly higher NPV in beta frequency band at the right fronto-temporo-occipital electrodes (Fp2, T4 and O2) in shunt responders compared to non-responders. By utilizing these differences, we were able to correctly identify responders and non-responders to shunt operation with a positive predictive value of 80% and a negative predictive value of 88%. Our findings indicate that NPV can be useful in noninvasively predicting the clinical outcome of shunt operation in patients with iNPH

Different Characteristics of Cognitive Impairment in Elderly Schizophrenia and Alzheimer's Disease in the Mild Cognitive Impairment Stage

We compared indices of the revised version of the Wechsler Memory Scale (WMS-R) and scaled scores of the five subtests of the revised version of the Wechsler Adult Intelligence Scale (WAIS-R) in 30 elderly schizophrenia (ES) patients and 25 Alzheimer's disease (AD) patients in the amnestic mild cognitive impairment (aMCI) stage (AD-aMCI). In the WMS-R, attention/concentration was rated lower and delayed recall was rated higher in ES than in AD-aMCI, although general memory was comparable in the two groups. In WAIS-R, digit symbol substitution, similarity, picture completion, and block design scores were significantly lower in ES than in AD-aMCI, but the information scores were comparable between the two groups. Delayed recall and forgetfulness were less impaired, and attention, working memory and executive function were more impaired in ES than in AD-aMCI. These results should help clinicians to distinguish ES combined with AD-aMCI from ES alone

In vitro co-culture systems for studying molecular basis of cellular interaction between Aire-expressing medullary thymic epithelial cells and fresh thymocytes

We previously established three mouse cell lines (Aire+TEC1, Aire+TEC2 and Aire+DC) from the medullary thymic epithelial cells (mTECs) and dendritic cells (mDCs). These cells constitutively expressed “autoimmune regulator (Aire) gene” and they exhibited various features of self antigen-presenting cells (self-APCs) present in the thymic medullary region. Here, we confirmed our previous observation that Aire+ thymic epithelial cells adhere to fresh thymocytes and kill them by inducing apoptosis, thus potentially reproducing in vitro some aspects of the negative selection of T cells in vivo. In this system, a single Aire+ cell appeared able to kill ∼30 thymocytes within 24 hrs. Moreover, we observed that ectopic expression of peripheral tissue-specific antigens (TSAs), and expression of several surface markers involved in mTEC development, increased as Aire+ cell density increases toward confluency. Thus, these Aire+ cells appear to behave like differentiating mTECs as if they pass through the developmental stages from intermediate state toward mature state. Surprisingly, an in vitro co-culture system consisting of Aire+ cells and fractionated sub-populations of fresh thymocytes implied the possible existence of two distinct subtypes of thymocytes (named as CD4+ killer and CD4− rescuer) that may determine the fate (dead or alive) of the differentiating Aire+mTECs. Thus, our in vitro co-culture system appears to mimic a part of “in vivo thymic crosstalk”