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3.
ACS Appl Mater Interfaces ; 11(4): 4637-4648, 2019 Jan 30.
Article in English | MEDLINE | ID: mdl-30623638

ABSTRACT

The surface electronic properties of the light absorber and band alignment at the p/n heterointerface are key issues for high-performance heterojunction solar cells. We investigated the band alignment of the heterointerface between cadmium sulfide (CdS) and Ge-incorporated Cu2ZnSnSe4 (CZTGSe), with Ge/(Ge + Sn) ratios ( x) between 0 and 0.4, by X-ray photoelectron, ultraviolet, and inversed photoemission spectroscopies (XPS, UPS, and IPES, respectively). In particular, we used interface-induced band bending in order to determine the conduction band offset (CBO) and valence-band offset (VBO), which were calculated from the core-level shifts of each element in both the CdS overlayer and the CZTGSe bottom layer. Moreover, the surface electronic properties of CZTGSe were also investigated by laser-irradiated XPS. The CBO at the CdS/CZTGSe heterointerface decreased linearly, from +0.36 to +0.20 eV, as x was increased from 0 to 0.4; in contrast, the VBO at the CdS/CZTGSe heterointerface was independent of Ge content. Both UPS and IPES revealed that the Fermi level at the CZTGSe surface is located near the center of the band gap. The hole concentration at the CZTGSe surface was on the order of 1011 cm-3, which is much smaller than that of the bulk (∼1016 cm-3). We discuss the differences in hole deficiencies near the surface and in the bulk on the basis of laser-irradiated XPS and conclude that hole deficiencies are due to defects distributed near the surface with densities that are lower than in the bulk, and the Fermi level is not pinned at the CZTGSe surface.

4.
J Stroke Cerebrovasc Dis ; 27(5): 1338-1342, 2018 May.
Article in English | MEDLINE | ID: mdl-29397310

ABSTRACT

BACKGROUND: Direct oral coagulants (DOAC) have been shown to decrease the frequency of intracerebral hemorrhage (ICH) compared with warfarin. However, the precise characteristics, such as the size and locations of the hemorrhage, and outcome and onset time of ICH in patient taking DOAC are not fully elucidated. METHODS: We retrospectively analyzed the characteristics of symptomatic patients with ICH taking either DOAC or warfarin between January 2012 and December 2015. RESULTS: Out of 400 consecutive patients with ICH, 15 patients were DOAC-ICH and 24 patients were warfarin-ICH. DOAC-ICH was observed in 6 patients with 10 mg of rivaroxaban, 5 patients with 15 mg of rivaroxaban, and 1 patient with 10 mg of apixaban, 5 mg of apixaban, 30 mg of edoxaban, and 60 mg of edoxaban. Prothrombin time was well controlled in most of the warfarin-ICH patients (83.3%). The locations of ICH were similar in both groups; however, median ICH volume was significantly smaller in DOAC-ICH patients than in warfarin-ICH patients (P < .01) and ICH around basal ganglia seemed to show great difference between the groups. DOAC-ICH patients showed better neurological outcome at the time of discharge than warfarin patients (P < .01), and the ratio of good prognosis was significantly higher in the DOAC-ICH patients than in the warfarin-ICH patients (P < .01). The onset of warfarin-ICH was frequently observed in the morning and evening, whereas DOAC-ICH did not show any specific onset time. CONCLUSIONS: Patients with DOAC-ICH showed smaller ICH volume and better clinical outcomes than patients with warfarin-ICH, and DOAC-ICH did not show any specific onset peak.


Subject(s)
Anticoagulants/adverse effects , Cerebral Hemorrhage/chemically induced , Pyrazoles/adverse effects , Pyridines/adverse effects , Pyridones/adverse effects , Rivaroxaban/adverse effects , Thiazoles/adverse effects , Warfarin/adverse effects , Administration, Oral , Adult , Aged , Aged, 80 and over , Anticoagulants/administration & dosage , Cerebral Hemorrhage/diagnostic imaging , Circadian Rhythm , Female , Humans , Male , Middle Aged , Prothrombin Time , Pyrazoles/administration & dosage , Pyridines/administration & dosage , Pyridones/administration & dosage , Retrospective Studies , Risk Factors , Rivaroxaban/administration & dosage , Thiazoles/administration & dosage , Time Factors , Treatment Outcome , Warfarin/administration & dosage
6.
ACS Appl Mater Interfaces ; 8(39): 26013-26018, 2016 Oct 05.
Article in English | MEDLINE | ID: mdl-27611007

ABSTRACT

Organolead-halide perovskites can be promising materials for next-generation solar cells because of its high power conversion efficiency. The method of precise fabrication is required because both solution-process and vacuum-process fabrication of the perovskite have problems of controllability and reproducibility. Vacuum deposition process was expected to achieve precise control; however, vaporization of amine compound significantly degrades the controllability of deposition rate. Here we achieved the reduction of the vaporization by implementing the laser evaporation system for the codeposition of perovskite. Locally irradiated continuous-wave lasers on the source materials realized the reduced vaporization of CH3NH3I. The deposition rate was stabilized for several hours by adjusting the duty ratio of modulated laser based on proportional-integral control. Organic-photovoltaic-type perovskite solar cells were fabricated by codeposition of PbI2 and CH3NH3I. A power-conversion efficiency of 16.0% with reduced hysteresis was achieved.

7.
J Vis Exp ; (105): e53276, 2015 Nov 09.
Article in English | MEDLINE | ID: mdl-26575244

ABSTRACT

One of the potential applications of metal nanostructures is light trapping in solar cells, where unique optical properties of nanosized metals, commonly known as plasmonic effects, play an important role. Research in this field has, however, been impeded owing to the difficulty of fabricating devices containing the desired functional metal nanostructures. In order to provide a viable strategy to this issue, we herein show a transfer printing-based approach that allows the quick and low-cost integration of designed metal nanostructures with a variety of device architectures, including solar cells. Nanopillar poly(dimethylsiloxane) (PDMS) stamps were fabricated from a commercially available nanohole plastic film as a master mold. On this nanopatterned PDMS stamps, Ag films were deposited, which were then transfer-printed onto block copolymer (binding layer)-coated hydrogenated microcrystalline Si (µc-Si:H) surface to afford ordered Ag nanodisk structures. It was confirmed that the resulting Ag nanodisk-incorporated µc-Si:H solar cells show higher performances compared to a cell without the transfer-printed Ag nanodisks, thanks to plasmonic light trapping effect derived from the Ag nanodisks. Because of the simplicity and versatility, further device application would also be feasible thorough this approach.


Subject(s)
Metal Nanoparticles/chemistry , Nanostructures/chemistry , Silicon/chemistry , Silver/chemistry , Solar Energy , Dimethylpolysiloxanes/chemistry , Hydrogen/chemistry , Light , Printing
8.
Chem Commun (Camb) ; 50(3): 362-4, 2014 Jan 11.
Article in English | MEDLINE | ID: mdl-24247179

ABSTRACT

A method to fabricate metal nanostructures by transfer printing, applicable to textured surfaces, is described. The key is the use of self-assembled polystyrene-block-poly-2-vinylpyridine thin films as binding layers. The plasmonic properties of the obtained metal (Ag) nanostructures showed the potential of this method in the design of novel devices.

9.
Int J Pharm ; 320(1-2): 71-8, 2006 Aug 31.
Article in English | MEDLINE | ID: mdl-16750604

ABSTRACT

The industrial manufacturing of rapidly disintegrating oral tablets with a sufficient tensile strength was investigated. The manufacturing method of the tablets involved the crystalline transition of amorphous sucrose that was produced in the process of fluidized bed granulation of mannitol using sucrose solution as a binder. The aim of this article was to clarify the usefulness of amorphous sucrose formed during the granulation for the rapidly disintegrating oral tablets manufacturing, and to investigate the effects of crystalline transition of the amorphous sucrose in granules on the characteristics of the resultant tablets prepared by this crystalline transition (CT) method. The X-ray diffraction measurement and thermal analysis showed that amorphous sucrose was effectively formed in granules consisting of 95% mannitol and 5% sucrose when the granulation was performed on the condition of water content of 4%. The tensile strength of tablets comprised of the granules, which were compressed before the crystallization of amorphous sucrose, increased remarkably after storage, because new internal solid bridges were formed in the tablets as a result of the crystallization. We conclude that rapidly disintegrating oral tablets can effectively be manufactured by the CT method using the granules obtained by the fluidized bed granulation method.


Subject(s)
Excipients/chemistry , Mannitol/chemistry , Sucrose/chemistry , Tablets , Technology, Pharmaceutical , Administration, Oral , Calorimetry, Differential Scanning , Crystallization , Crystallography, X-Ray , Drug Storage , Porosity , Solubility , Temperature , Tensile Strength , Time Factors
10.
Chem Pharm Bull (Tokyo) ; 54(2): 175-80, 2006 Feb.
Article in English | MEDLINE | ID: mdl-16462059

ABSTRACT

The aim of this article was to determine the optimal ingredients for the rapidly disintegrating oral tablets prepared by the crystalline transition method (CT method). The effect of ingredients (diluent, active drug substance and amorphous sugar) on the characteristics of the tablets was investigated. The ingredients were compressed and the resultant tablets were stored under various conditions. The oral disintegration time of the tablet significantly depended on diluents, due to differences in the penetration of a small amount of water in the mouth and the viscous area formed inside the tablet. The oral disintegration time was 10-30 s for tablets with a tensile strength of approximately 1 MPa, when erythritol, mannitol or xylitol was used as the diluent. The increase in the tensile strength of tablets containing highly water-soluble active drug substances during storage was as large as that of tablets without active drug substances, while the increase in the tensile strength of tablets containing low water-soluble active drug substances was small. It was therefore found that highly water-soluble active drug substances were more suitable for the formulation prepared by the CT method than low water-soluble active drug substances. Irrespective of the type of amorphous sugar (amorphous sucrose, lactose or maltose) used, the porosity of tablets with 1 MPa of tensile strength was 30-40%, and their oral disintegration time was 10-20 s. The optimal ingredients for rapidly disintegrating oral tablets with reasonable tensile strength and disintegration time were therefore determined from these results.


Subject(s)
Chemistry, Pharmaceutical/methods , Tablets , Absorption , Administration, Oral , Carbohydrates , Crystallization , Crystallography, X-Ray , Excipients , Humidity , Lactose , Porosity , Solubility , Tensile Strength , Thermodynamics
11.
Int J Pharm ; 296(1-2): 64-72, 2005 May 30.
Article in English | MEDLINE | ID: mdl-15885456

ABSTRACT

The aim of this study is to investigate the factors affecting the characteristics of rapidly disintegrating tablets containing an amorphous ingredient prepared by crystalline transition method (CTM) under various storage conditions. Effect of storage conditions and formulating ratio of amorphous sucrose on the characteristic changes (tensile strength, porosity, and disintegration time) of the rapidly disintegrating tablets was studied. The storage conditions of different temperature and humidity affected the rate of crystalline transition and the increase in the tablet tensile strength. The faster crystalline transition resulted in a faster rate of increase in the tablet tensile strength. Regarding the effect of the formulating ratio of amorphous sucrose, in the case of 20-100%, the tensile strength after storage as a function of the porosity could be plotted on the same curve. For tablets containing 100% amorphous sucrose, the tablets with different porosity changed to almost the same structure due to the crystalline transition. Hence, the higher formulating ratio of amorphous sucrose provided the longer disintegration time in the mouth. Therefore, we concluded that the formulating ratio of 10-20% of the amorphous sucrose in the tablet is suitable for the rapidly disintegrating tablet in the mouth when prepared by CTM.


Subject(s)
Mouth/metabolism , Sucrose/chemistry , Sucrose/metabolism , Crystallization , Humans , Mouth/drug effects , Porosity , Solubility , Sucrose/administration & dosage , Tablets , Tensile Strength , Time Factors
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