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Standard Quality Control Testing, Virus Penetration, and Glove Durability
Published in Robert N. Phalen, Howard I. Maibach, Protective Gloves for Occupational Use, 2023
Oversized, circular specimens were sampled from the gloves' dorsum or palm. The nonconducting (to direct current) sample was clamped in a vertical position between two chambers later filled with a dilute aqueous salt solution held to 37°C (Figure 11.1). Electrodes were placed in each chamber (and connected to a lock-in amplifier). The electrodes served as both a source of a sinusoidally varying alternating current excitation voltage and as a phase-sensitive detector of current output from the cell. A displacement volume-controlling cam-and-race assembly, driven by a tunable-frequency motor set at a frequency of 0.8 Hz, delivered liquid into and out of one chamber. The other chamber was passively restored from a reservoir. At initial (and maximal) displacement, the membrane underwent a strain of approximately 35% in each direction. The onset of membrane failure was confirmed by recording a predefined slope change in transmembrane capacitance. The count of elapsed cycles corresponding to that failure event is recorded as the lifetime. Data were right-censored, in that failure events that occurred beyond 12,000 cycles were not recorded. Lifetime data were analyzed using the exact log-rank method, with appropriate significance-level adjustment for multiple comparisons.
Optical Imaging
Published in George C. Kagadis, Nancy L. Ford, Dimitrios N. Karnabatidis, George K. Loudos, Handbook of Small Animal Imaging, 2018
Frequency-domain imaging is commonly utilized in transmission optical imaging modalities such as diffuse optical imaging and tomography (DOT) and fluorescence molecular tomography (FMT). Instead of a steady-state light source, the light that is injected into the animal is amplitude-modulated at frequencies above 10 MHz. This amplitude modulation has several advantages. First, with a lock-in amplifier, it can increase the sensitivity on the detector side of the imaging apparatus. Second, through appropriate analysis during image reconstruction the absorption and scattering maps can be independently reconstructed. Frequency-domain imaging can be accomplished with integrating detectors such as CCDs provided that a filter with fast temporal dynamics is coupled to the camera. Unlike CW imaging, frequency-domain imaging can involve wave-like phenomena that propagate through tissue. These diffuse-photon density waves (DPDWs) can interact with tissue in a manner that can be modeled as wave scattering and diffraction. Wave-based image reconstruction methods such as diffraction tomography have been explored for this mode of optical imaging (Li et al. 1997; Liu et al. 1999; Matson and Liu 1999a,b).
Detecting Singlet Oxygen by Low-Level Chemiluminescence
Published in Robert A. Greenwald, CRC Handbook of Methods for Oxygen Radical Research, 2018
1O2 Monomol emission occurs in the infrared region at 1270 nm and is currently measured with liquid nitrogen-cooled germanium photodetectors of the type J-16 (Judson Infrared Inc., Ft. Washington, Pa.),12 EO-817 (North Coast Optical Systems and Sensors),15 or 403L (Applied Detector Corporation, Fresno, Calif.).16 The EO-817 germanium photodiode was reported to have a specific detectivity about 2 × 103-fold higher than the lead sulfide detector.17 Detector signals are processed by an amplifier (Burr-Brown amplifier,; Evans Assoc. model 4110 lock-in amplifier) and displayed on a recorder. Technical characteristics for this method of detecting 1O2 monomol emission are detailed elsewhere.15-17 A comparison of the detection limits between a J-16 germanium photodetector (Judson Infrared Inc.) and a red-sensitive photomultiplier (EMI 9658A), on the basis of 1O2 generated by the H2O2/ OCl− chemical reaction, was recently presented.12
Formulation and performance evaluation of emulgel platform for combined skin delivery of curcumin and propolis
Published in Pharmaceutical Development and Technology, 2023
Rafaela Said dos Santos, Jéssica Bassi da Silva, Camila Felix Vecchi, Katieli da Silva Souza Campanholi, Hélen Cassia Rosseto, Mariana Carla de Oliveira, Francielle Pelegrin Garcia, Rodolfo Bento Balbinot, Lidiane Vizioli de Castro Hoshino, Tânia Ueda Nakamura, Celso Vataru Nakamura, Mauro Luciano Baesso, Wilker Caetano, Marcos Luciano Bruschi
The porcine skin sample received an emulgel sample (50 μg) homogeneously distributed over a 1-cm2 surface. After 30 min, the sample was analyzed by PAS using equipment composed of 1000 W Xenon arc lamp (Oriel, model 68820) as a light source (nominal power of 800 W). The light can be diffracted by passing through the 3.16 mm input and output slits of the monochromator (Oriel, model 77250). Afterwards, it can be modulated at 13 Hz using a mechanical chopper (Stanford Research Systems, model SR 540) to focus on the sample. Band-pass filters were utilized to eliminate the higher-order diffraction. The treated skin sample was placed inside the photoacoustic cell and a transparent quartz window (diameter of 8 mm and thickness of 2 mm) was utilized to seal it. The periodic sample heating generates pressure changes resulting in the photoacoustic signal that can be captured by a capacitive microphone (Brüel and Klaer model 2669). In addition, a lock-in amplifier by EG&G Instruments, model 5110, was utilized. The thermal diffusion length was used for calculating the depth of tissue that contributed to the photoacoustic signal (Baesso et al. 1994; Ames et al. 2017) according to Equation 3: s is the thermal diffusion length, D is the sample thermal diffusivity (4.1 × 10−4 cm2/s), and πf is the light modulation frequency (13 Hz). Consequently, μs was 32 μm for the skin, which ensures that readings are taken close to the surfaces on which the light is incident, being the sample mean thickness always around 1080 μm.
Ultrasound irradiation effect on photosynthesis and transpiration of aquatic lirium plants
Published in International Journal of Radiation Biology, 2021
José Antonio Calderón, Jeniffer Yeismar Calderón, Alejandro Rojas, Joel Hernández-Wong, Uriel Nogal, Ernesto Marin, Antonio Gustavo Juárez-Gracia, Gabriel Peña-Rodríguez, José Bruno Rojas-Trigos
The bottom of Figure 2 shows an enlarged view of the scheme of the PA cell, which consists of a solid body containing an air chamber with a volume of about 3.4cm3 connected to the sensitive acoustic detector (Pressure-field ½” microphone Brüel & Kjaer, model 4192) through a cylindrical channel with a diameter of 2mm. The upper chamber opening is sealed with a quartz window, while the lower opening is completely covered with the specimen (leaf) using vacuum grease to adhere it to its outer surface. In this form, one side of the leaf is in contact with the air inside the chamber. The other is held on a flat backing of glass that keeps it rigid and slightly pressed on the base of the PA chamber using two brackets. When the light beam passes through the window, it reaches and perpendicularly impinges on the leaf’s surface. The light energy absorbed by the leaf generates an acoustic signal in the chamber that consists of two contributions: the photothermal response, which comes from the conversion of part of the absorbed light energy in heat that diffuse to the PA chamber; and the photobaric response, that comes from the modulated emission of oxygen during the leaf photosynthetic process. The acoustic detector senses the acoustic signal generated in the chamber. It is turned into an electrical signal, which is directed to a Lock-in amplifier (SR-850) synchronized at the fixed modulated frequency. The process is fully automatically controlled by a personal computer and a GPIB (General-purpose interface bus) electronic card.
Versatility of targeted antibiotic-loaded gold nanoconstructs for the treatment of biofilm-associated bacterial infections
Published in International Journal of Hyperthermia, 2018
Daniel G. Meeker, Tengjiao Wang, Walter N. Harrington, Vladimir P. Zharov, Sarah A. Johnson, Samir V. Jenkins, Stephanie E. Oyibo, Christopher M. Walker, Weston B. Mills, Mark E. Shirtliff, Karen E. Beenken, Jingyi Chen, Mark S. Smeltzer
Photothermal microscopy was performed as previously described [18]. Briefly, a custom built platform based on an inverted Olympus IX73 (Olympus America, Inc., Central Valley, PA, USA) using a 3-wavelength Wavelength Division Multiplexer (WDM or RGB Combiner, RGB46HF; Thorlabs, Newton, NJ, USA) was used to combine 488 nm (fluorescence excitation: IQ1C45 (488–60) laser diode; Power Technology, Little Rock, AR, USA), 532 nm (PT pump: LabSpec 532 nm DPSS Laser; Laserglow Technologies, LLS series, Toronto, Canada) and 635 nm (PT probe: LP637 SM Fiber-Pigtailed Laser Diode; Thorlabs, Newton, NJ, USA) laser beams into a single mode fibre. High resolution confocal fluorescence and PTM imaging were carried out simultaneously by steering laser beams using galvo-mirrors (GVSM002; Thorlabs, Newton, NJ, USA) across the sample. Probe beam intensity was collected using 40× objective located above the sample and measured by amplified photodiode (PDA10A; Thorlabs, Newton, NJ, USA). PT signal was measured using a digital lock-in amplifier (MFLI, 500 kHz, 60MSa/s, Zurich Instruments, Switzerland) and recorded using custom software developed on the LabView platform. Conventional fluorescent imaging was carried out using a CCD camera DP80 (Olympus America, Central Valley, PA, USA). PT and fluorescence images were merged and PT signal was quantified pixel-by-pixel using ImageJ software. Each AuNC sample was run in triplicate and 95% confidence intervals were obtained for labelling efficiency and signal intensity relative to a control of a sample of bacteria alone.