RESUMEN
A light-sensitive moiety, e.g., azobenzene, for the light-sensitive liposomal drug carrier has shown advantages as an advanced drug delivery system in site-specific smart therapy due to its reversible photoisomerization characteristics. In this work, a series of 4-position-cholesterol-functionalized azobenzene derivatives with 4'-position substituted pyridine, quinoline, isoquinoline, triethylamine, or ethylenediamine were synthesized, and the relationship between the molecular structure and drug release behaviors was clarified. We found that the charge and electrophilicity of substituents were two important factors (expressed as the characteristic time) that can precisely regulate the isomerization ratio in the liposomal system. There was an approximately linear correlation between the characteristic time of photoisomerization and the fitted first-order constant of photoinduced drug release rate. The photoinduced drug release could be achieved at the desired time and in an appropriate amount by tailoring the substituents at the 4'-position of azobenzene-cholesterol derivatives.
RESUMEN
An impulse measurement system based on a simple pendulum is newly developed. The system has a resolution of 10-7 Ns for ablation events induced by a single laser at a pulse rate of 2 Hz or less. For ablation events at 10 Hz and above, the system can record the impulse as an average force. The impulse generated by a Nd:YAG pulse laser irradiating a 7075 aluminum alloy is investigated in vacuum. The impulse arises at 3 J/cm2 and the momentum coupling factor, Cm, plateaus at approximately 20 µNs/J over a range of 5 to 50 J/cm2 without producing a plasma shielding effect. Cm is characterized by only fluence independent of pulse width in the range of 10 to 20 ns. This result indicates that it should be feasible to deorbit a 150 kg abandoned satellite at an altitude of 1200 km using a chaser satellite equipped with a 100 W laser.
RESUMEN
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused a worldwide pandemic. Ultraviolet (UV) is regarded as a very powerful tool against SARS-CoV-2. However, the inactivating effects of different UV wavelengths on SARS-CoV-2 under the same conditions have hardly been compared. Here, we showed that SARS-CoV-2 cultured in Dulbecco's modified Eagle's medium and 2% fetal bovine serum was efficiently inactivated by irradiation with 222, 254, and 265 wavelengths UV, but not at 308 nm. In addition, it was revealed that UV absorption by DMEM-2% FBS is very efficient at 222 nm. Our results present potentially important information for selecting the optimum UV wavelength according to the application.
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SARS-CoV-2 is the causative agent of COVID-19, which is a global pandemic. SARS-CoV-2 is transmitted rapidly via contaminated surfaces and aerosols, emphasizing the importance of environmental disinfection to block the spread of virus. Ultraviolet C radiation and chemical compounds are effective for SARS-CoV-2 disinfection, but can only be applied in the absence of humans due to their toxicities. Therefore, development of disinfectants that can be applied in working spaces without evacuating people is needed. Here we showed that TiO2-mediated photocatalytic reaction inactivates SARS-CoV-2 in a time-dependent manner and decreases its infectivity by 99.9% after 20 min and 120 min of treatment in aerosol and liquid, respectively. The mechanistic effects of TiO2 photocatalyst on SARS-CoV-2 virion included decreased total observed virion count, increased virion size, and reduced particle surface spike structure, as determined by transmission electron microscopy. Damage to viral proteins and genome was further confirmed by western blotting and RT-qPCR, respectively. The multi-antiviral effects of TiO2-mediated photocatalytic reaction implies universal disinfection potential for different infectious agents. Notably, TiO2 has no adverse effects on human health, and therefore, TiO2-induced photocatalytic reaction is suitable for disinfection of SARS-CoV-2 and other emerging infectious disease-causing agents in human habitation.
Asunto(s)
Desinfección/métodos , SARS-CoV-2/efectos de los fármacos , Titanio/farmacología , Animales , COVID-19/metabolismo , Línea Celular , Chlorocebus aethiops , Humanos , Pandemias , ARN Viral/efectos de los fármacos , SARS-CoV-2/patogenicidad , Titanio/química , Células VeroRESUMEN
We experimentally demonstrated a dual-wavelength independently mode-locked Yb:YAG ceramic laser in a single cavity. Dual-wavelength mode locking at 1033.6 and 1047.6 nm was operated simultaneously in one beam. Each pulse width was measured to be approximately 380 fs using an autocorrelator. The spectral widths were 4.50 nm centered at 1033.6 nm and 3.08 nm centered at 1047.6 nm. To the best of our knowledge, this is the first dual-wavelength mode locking achieved in Yb-doped solid-state lasers.
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Cerámica/química , Diseño Asistido por Computadora , Rayos Láser , Modelos Teóricos , Simulación por Computador , Diseño de Equipo , Análisis de Falla de EquipoRESUMEN
A diode-pumped passively mode-locked Yb:YAG ceramic laser was demonstrated. 417 and 286 fs pulses with average powers of 250 and 25 mW were obtained at 1030 nm using 1 and 0.1% output couplers, respectively. 233 fs pulses with an average power of 20 mW were also obtained at a center wavelength of 1048.3 nm using a 0.1% output coupler. To the best of our knowledge, this is the first demonstration of a diode-pumped mode-locked Yb:YAG ceramic laser.
Asunto(s)
Cerámica , Láseres de Estado Sólido , Diseño Asistido por Computadora , Diseño de Equipo , Análisis de Falla de Equipo , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
Efficient laser performance is demonstrated with Nd:GdVO4 crystals grown by the floating zone method. With a 2-at. % Nd-doped crystal a slope efficiency of 67% is achieved with pumping at 808 nm. We also find that pumping at 879 nm with a bandwidth of 1.8 nm is practical for laser diode pumping. With this pumping level the slope efficiency reaches 78%. High-quality Nd:GdVO4 crystals are successfully grown with as much as 15-at.% Nd concentration by the floating zone method without inclusions or macroscopic defects. Homogeneity and high reproducibility of crystal growth are confirmed.