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Control of the charge state of the nitrogen-vacancy (NV) center is crucial because of its instability and its transitions between the negative (NV–) and neutral (NV0) NV charge states under laser irradiation In this study, we fabricated an n-i-n junction, with an i-layer sandwiched between two phosphorus-doped n-layers; then, we measured the charge state of NV centers under steady state and laser irradiation in a known band structure where the Fermi energy changes gradually. The steady-state charge state measured by a nondestructive single shot exhibited stable NV– and NV0 signals when the Fermi level was even slightly above and below the transition level, respectively. This result indicates that the charge state can be significantly stabilized through band engineering. Both charge-state populations were observed only when the Fermi level was close to the transition level. Under continuous green laser irradiation, the ratio of NV– measured by the photoluminescence spectra changed gradually with the Fermi level in the depletion layer because of the balance between excitation from the laser and the supply of charge from the band. This outcome agrees reasonably with the calculated bands. Furthermore, we measured the PL spectra of the ensemble NV centers and discovered that their charge state can be well-controlled, as in the single NV center. The charge state of the i-layer at the interface can be stabilized by depositing a thin n-layer on the surface. These results would contribute significantly to improve sensor performance. [ABSTRACT FROM AUTHOR]

We have observed a new optical transition in the photoreflectance spectra of indirect-gap BiOCl thin films, which were grown on SrTiO3 substrates. The position of this transition is close in energy to its bulk critical point (CP) energy. Moreover, these are significantly lower than a higher-lying direct-type CP from an energetic point of view. The spectral line shape analysis for our observed signal suggests the presence of an excitonic effect of this compound. We determined its dependence of the optical anomaly on temperature ranging from 80 K to RT. We adopted the Varshni model for this analysis. At last, we compared photonic properties of BiOCl with those of an element and binary semiconductors. [ABSTRACT FROM AUTHOR]

We report on a bistable defect known as M-center, here introduced in n-type 4H-SiC by 2 MeV He ion implantation. Deep levels of the M-center are investigated by means of junction spectroscopy techniques, namely, deep level transient spectroscopy (DLTS) and isothermal DLTS. In addition to previously reported three deep levels arising from the M-center (labeled as M1, M2, and M3), we provide direct evidence on the existence of a fourth transition (labeled as M4) with an activation energy of 0.86 eV. Activation energies and apparent capture cross sections for all four metastable defects are determined. From first-principles calculations, it is shown that the observed features of the M-center, including the charge state character, transition levels, bi-stability dynamics, and annealing, are all accounted for by a carbon self-interstitial. [ABSTRACT FROM AUTHOR]

The realization of electroluminescence (EL) of negatively charged nitrogen vacancy (NV−) centers is important toward all-electrical control of diamond quantum devices. In this study, we demonstrated electrical excitation and detection of EL of single NV− centers by using lateral diamond p+–i(n−)–n+ diodes. It had been grown by homoepitaxy using the plasma enhanced chemical vapor deposition technique. We introduced a lightly phosphorus doped i(n−) layer to stabilize the negative state of NV centers. It was estimated that the efficiency of the electrical excitation rate of the NV center was more than 30 times enhanced by introducing lateral diamond p+–i(n−)–n+ diodes structure compared with the previous vertical diode. Furthermore, the EL of a single NV− center embedded in the i(n−) layer region was characterized. The results show that the charge state of the single NV centers can be manipulated by the voltage applied to the p+–i(n−)–n+ diode, where the emission of EL is increasingly dominated by NV− in the range of 30 to 50 V. [ABSTRACT FROM AUTHOR]

Teruhiko Makino,1 Yoshiaki Takegami,1 Mati Ur Rehman,1 Yoko Yoshihisa,1 Waka Ishida,2 Takashi Toyomoto,3 Tadamichi Shimizu11Department of Dermatology, University of Toyama, Toyama, Japan; 2Department of Dermatology, Niigata Central Hospital, Joetsu, Japan; 3Department of Dermatology, Saiseikai Takaoka Hospital, Takaoka, JapanBackground: The long-term follow-up of chronic urticaria (CU) is important to ensure the adequate treatment of patients. Olopatadine hydrochloride is one of the second-generation nonsedating antihistamines.Methods: This study was designed to assess the optimal dose of olopatadine to suppress symptoms of chronic urticarial itch in well-controlled patients. After CU patients were treated with 10 mg olopatadine, patients having a visual analogue scale (VAS) itch score of less than 20 were randomly allocated into one of three groups: 10 mg/day (n = 35), 5 mg/day (n = 30), or no medication (n = 32).Results: The suppressive effects of both the 5 mg and 10 mg olopatadine treatments on the VAS itch score were more significant and longer lasting over a period of 4 weeks than the no-medication treatment. Both the 5-mg group and the 10-mg group showed improved urticarial symptoms and maintained their VAS itch score within normal limits compared to the no-medication group. The differences between the 5-mg and 10-mg groups were not significant.Conclusion: These results demonstrate that treatment with olopatadine at a dose of 5 mg once daily is effective and safe for the management and prevention of CU symptoms for itch in well-controlled patients.Keywords: chronic urticaria, olopatadine, dose, antihistamine, itch, histamine

Takako Yamakoshi,1 Teruhiko Makino,1 Kenji Matsunaga,1 Yoko Yoshihisa,1 Mati Ur Rehman,1 Taisuke Seki,2 Yoshito Hayashi,3 Tadamichi Shimizu11Department of Dermatology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama-shi, Toyama; 2Seki Dermatological Clinic, Toyama-shi, Toyama; 3Otsuka Pharmaceutical Factory Inc, Naruto-shi, Tokushima, JapanBackground: Oronine H® ointment, which contains chlorhexidine gluconate as its active component, is a well known disinfectant, and has been widely used for treatment of acne in Japan. In this study, we investigated the inhibitory effect of this ointment on the formation of comedones induced by application of 50% oleic acid on the orifices of the external auditory canals of rabbits.Methods: The application sites were observed with a dermatoscope, and the area of the hair pores was measured using an Image analysis software program.Results: The chlorhexidine gluconate ointment inhibited comedone formation significantly more effectively than the liquid paraffin used as a control (P < 0.001). We also investigated the therapeutic effect of this ointment on comedones. After starting application of chlorhexidine gluconate ointment or liquid paraffin on the comedone area, the hair pore size was gradually decreased in the group treated with chlorhexidine gluconate ointment compared with the hair pore size at baseline.Conclusion: These results suggest that chlorhexidine gluconate ointment is effective for inhibiting comedone formation as well as for treating already formed comedones. Chlorhexidine gluconate ointment is a useful topical medicine for the treatment of early-stage acne and for preventing acne.Keywords: chlorhexidine gluconate ointment, comedones, dermatoscope, oleic acid