Imaging AOTFs with low RF Power in deep-UV and mid-IR

Acousto-Optic Tunable Filters (AOTFs) are commonly used for applications where high speed tuning and narrow spectral resolu- tion are required. The RF drive power for peak diffraction efficiency increases as λ2 and depends on the acousto-optic figure of merit (M2), which is material dependent. In the VIS-IR region between 450 nm and 4.5 μm tellurium dioxide (TeO2) is the common material of choice due to the high M2. At longer wavelengths (up to about 12 μm) the mercurous halides and single crystal tellurium show promise. In both cases the λ2 dependency dominates the RF power consumption and for wavelengths beyond 3.5 μm the RF power consumption is above the practical limit (>5W) for larger aperture AOTF(> 10 mm × 10 mm). In the UV range (200 nm – 400 nm) the λ2 dependency is no longer dominant and the power consumption depends mainly on the M2,however, for most materials transparent in the UV the M2 is poor and thus the drive power will again be excessive (>5W). In order to reduce the RF power requirement to reach peak diffraction efficiency, a resonant configuration in crystal quartz shows promise, especially in the UV range due to its low acoustic attenuation. We describe an AOTF operating in resonance made of crystal quartz, where the reduction of RF power consumption will be reduced by a factor between 15 and 20 compared to a conventional AOTF, thus reducing the power consumption to be within the practical limit (<5W)

Effective piezoelectric activity of zinc oxide films grown by RF planar magnetron sputtering

We present a study of the effective piezoelectric activity of thin ZnO films produced by RF planar magnetron sputtering. The energetic plasma particles which bombard the substrate in the above deposition system increase the substrate temperature, thus causing a gradual variation in film structure during the beginning of the film growth. As a result, a precursor layer is formed which consists of small randomly oriented crystallites, and exhibits poor piezoelectric activity. Hence, the film thickness responsible for piezoelectric activity is generally less than the physical thickness of the film. This leads to an increase in the resonant frequency of the film. For example, a film designed to have a half-wave resonance at 288 MHz, was found to be resonant at 332 MHz. The poorly structured initial layer meant in this typical case that only 87 % of this film volume exhibited piezoelectric activity. Investigations based on the deposition conditions (substrate temperature, and deposition rate), the optical losses, SEM imaging and RF electrical behaviour are presented in this letter

Effects of a series of triorganotins on ATP levels in human natural killer cells

Natural killer (NK) cells are our initial immune defense against viral infections and cancer development. Thus, agents that are able to interfere with their function increase the risk of cancer and/or infection. A series of triorganotins (trimethyltin (TMT), dimethylphenyltin (DMPT), methyldiphenyltin (MDPT), and triphenyltin (TPT)) have been shown to decrease the lytic function of human NK cells. TPT and MDPT were much more effective than DMPT or TMT at reducing lytic function. This study investigates the role that decreased ATP levels may play in decreases in the lytic function of NK cells induced by these organotins (OTs). A 24h exposure to as high as 10μM TMT caused no decrease in ATP levels even though this level of TMT caused a greater than 75% loss of lytic function. TPT at 200nM caused a decrease in ATP levels of about 20% while decreasing lytic function by greater than 85%. There was no association between ATP levels and lytic function for any of the compounds when NK cells were exposed for 1 or 24h. However, after a 48h exposure to both DMPT and TPT decreased lytic function was associated with decreased ATP levels. There was an association between decreased lytic function and decreased ATP levels after a 6-day exposure to each of the four compounds. These studies indicate that the loss of lytic function seen after 1 and 24h exposures to this series of organotins cannot be accounted for by decreases in ATP. However, after longer exposures loss of lytic function may be in part be attributable to inadequate ATP levels

Book reviews

Teaching/Communication/Extension/Profession,

Evidence-Based Leadership Preparation Program Practices: From the Perceptions of Georgia Rural School Leaders

Phenomenological analysis was used to explore Georgia rural school principals’ lived experiences of effective school leadership preparedness. Four overarching themes were found: productive/favorable leadership preparation program culture, bridge theory and practice in educational leadership preparation program, multicultural competencies for practice, and recommendations for effective principal preparation. The findings revealed that school leaders need increased experiential learning opportunities, increased assignments applicable to daily leader tasks, and increased cultural awareness and diversity training in their preparation programs. Principal preparation programs should work with school districts to provide purposeful, collaborative, and sustainable professional learning to prepare competent school leaders. Further research includes recruiting more rural school principals to share their experiences and perceptions with principal preparation program providers in an effort to advance aspiring principal training. Implications for practice include equipping aspiring principals with the knowledge and skills to lead for equity to continue to have a pipeline of effective school leaders to serve in Georgia’s traditionally underserved areas

Human neuroglobin protein in cerebrospinal fluid

BACKGROUND: Neuroglobin is a hexacoordinated member of the globin family of proteins. It is predominantly localized to various brain regions and retina where it may play a role in protection against ischemia and nitric oxide-induced neural injury. Cerebrospinal fluid was collected from 12 chronic regional or systemic pain and 5 control subjects. Proteins were precipitated by addition of 50% 0.2 N acetic acid, 50% ethanol, 0.02% sodium bisulfite. The pellet was extensively digested with trypsin. Peptides were separated by capillary liquid chromatography using a gradient from 95% water to 95% acetonitrile in 0.2% formic acid, and eluted through a nanoelectrospray ionization interface into a quadrapole – time-of-flight dual mass spectrometer (QToF2, Waters, Milford, MA). Peptides were sequenced (PepSeq, MassLynx v3.5) and proteins identified using MASCOT (®). RESULTS: Six different neuroglobin peptides were identified in various combinations in 3 of 9 female pain subjects, but none in male pain, or female or male control subjects. CONCLUSION: This is the first description of neuroglobin in cerebrospinal fluid. The mechanism(s) leading to its release in chronic pain states remain to be defined

An unusual cause of dyspnoea – can you spot the diagnosis?

A 66-year-old man presented with a complaint of shortness of breath. He had a significant smoking history but no known medical conditions. Two years prior, he had been involved in a motor vehicle accident and sustained blunt trauma to his chest.http://www.ajtccm.org.za/index.php/SARJam2023Internal Medicin

Photoelastically induced light modulation in gradient index lenses

A new photoelastic light modulator is demonstrated based on the modulation of the birefringence and of the index profile in graded index lenses. Using the birefringence modulation we obtained 35% modulation depth in a quarter-pitch lens and 65% using a half pitch lens at acoustic frequencies up to the MHz range. Using the index profile modulation in a half-pitch lens as a fibre-to-fibre connector we obtained 15% modulation without the incorporation of any polarizer

Adverse effects of biologic anti-inflammatory agents on the respiratory system : a review

The therapy of autoimmune rheumatological conditions has undergone significant changes with the introduction of biologic antiinflammatory agents including cytokine antagonists and agents that interfere with the function of T and B cells or those that inhibit intracellular enzymes such as Janus kinase (JAK). Although useful to control inflammation, these agents may be associated with drug-induced lung disease, which may be difficult to differentiate from pulmonary disorders caused by the underlying autoimmune diseases. This review aims to provide a description of lung disease, both infectious and non-infectious, that may be induced by the administration of biologic anti-inflammatory agents with emphasis on inhibitors of tumour necrosis factor, interleukin-1, interleukin-6 and JAK.https://journals.co.za/journal/m.ajtccmam2022Internal Medicin