Surface texturing of CVD diamond assisted by ultrashort laser pulses

Diamond is a wide bandgap semiconductor with excellent physical properties which allow it to operate under extreme conditions. However, the technological use of diamond was mostly conceived for the fabrication of ultraviolet, ionizing radiation and nuclear detectors, of electron emitters, and of power electronic devices. The use of nanosecond pulse excimer lasers enabled the microstructuring of diamond surfaces, and refined techniques such as controlled ablation through graphitization and etching by two-photon surface excitation are being exploited for the nanostructuring of diamond. On the other hand, ultrashort pulse lasers paved the way for a more accurate diamond microstructuring, due to reduced thermal effects, as well as an effective surface nanostructuring, based on the formation of periodic structures at the nanoscale. It resulted in drastic modifications of the optical and electronic properties of diamond, of which “black diamond” films are an example for future high-temperature solar cells as well as for advanced optoelectronic platforms. Although experiments on diamond nanostructuring started almost 20 years ago, real applications are only today under implementation

The Influence of the Adreno-Steroids, Desoxycorticosterone, Cortisone and Acth on the Deposition of Ascorbic Acid in the Adrenalectomized Rat

Experimental evidence agrees that rats are able to synthesize Vitamin C, whereas human beings are not (32). The question then arises, do the adrenal glands play any significant role in the production of Vitamin C in the rat, if so, to what extent would the deposition of ascorbic acid be changed in various body tissue when the glands are removed ? With the forestated thought in mind, this report is designed to describe: 1. the physiological and morphological changes following adrenalectomy. 2. the physiological, morphological and biochemical changes following the administration of the adreno-steroids and ACTH. 3. the deposition of ascorbic acid in various body tissues in the adrenalectomized rat following the injection of adreno-steroids and ACTH. 4. the most effective variation of the adreno-steroids and ACTH upon ascorbic acid deposition

Functional Review and Macrostructure of the Caecum in Ardeidae

Situated on the lower digestive tract, caeca typically project cranially from the juncture of the small and large intestine. Recent studies have proposed that the role of caeca in the avian system is to act as fermentation chambers to synthesize vitamins, modulate gut microflora, and absorb nutrients; however, functionality differs with diet. Caeca are a typical characteristic of the avian gastrointestinal tract, with varying sizes and shapes, or even rudimentary or absent in some species. Caeca are notably singular and relatively small in Ardeids. Morphometric consistency in the number and presence of caeca on the lower intestinal tract of Ardeids was determined on a sample of 70 birds obtained from South Florida wildlife rehabilitation centers. This study also reports the findings of caeca length relative to morphometric and intestinal measurements. Caecum length relative to tarsus length was found to be significantly different between Cattle Egrets and Green Herons along with Green Herons and Great White Herons. Caecum length relative to small intestine length was significantly different between Great Egrets and Cattle Egrets. In order to further the understanding of Ardeid caeca, next steps include further research into the function of caeca in piscivorous birds and an in-depth look at the bacteria found in the avian caecum. In particular, future studies can be aimed at understanding why Green Herons differ so greatly from other Ardeids

Multi-wavelength, all-solid-state, continuous wave mode locked picosecond Raman laser

We demonstrate the operation of a cascaded continuous wave (CW) mode-locked Raman oscillator. The output pulses were compressed from 28 ps at 532 nm down to 6.5 ps at 559 nm (first Stokes) and 5.5 ps at 589 nm (second Stokes). The maximum output was 2.5 W at 559 nm and 1.4 W at 589 nm with slope efficiencies up to 52%. This technique allows simple and efficient generation of short-pulse radiation to the cascaded Stokes wavelengths, extending the mode-locked operation of Raman lasers to a wider range of visible wavelengths between 500 - 650 nm based on standard inexpensive picosecond Nd:YAG oscillators

Sum-frequency generation of 589 nm light with near-unit efficiency

We report on a laser source at 589 nm based on sum-frequency generation of two infrared laser at 1064 nm and 1319 nm. Output power as high as 800 mW are achieved starting from 370 mW at 1319 nm and 770 mW at 1064 nm, corresponding to converting roughly 90% of the 1319 nm photons entering the cavity. The power and frequency stability of this source are ideally suited for cooling and trapping of sodium atoms

Polarized micro-Raman studies of femtosecond laser written stress-induced optical waveguides in diamond

Understanding the physical mechanisms of the refractive index modulation induced by femtosecond laser writing is crucial for tailoring the properties of the resulting optical waveguides. In this work we apply polarized Raman spectroscopy to study the origin of stress-induced waveguides in diamond, produced by femtosecond laser writing. The change in the refractive index induced by the femtosecond laser in the crystal is derived from the measured stress in the waveguides. The results help to explain the waveguide polarization sensitive guiding mechanism, as well as providing a technique for their optimization.Comment: 5 pages, 4 figure

Optimisation of a Multi-Gravity Separator with Novel Modifications for the Recovery of Ferberite

This is the final version of the article. Available from MDPI via the DOI in this record.Tungsten is considered by the European Union as a critical raw material for future development due to its expected demand and scarcity of resource within Europe. It is therefore, critical to optimize European tungsten operations and maximise recoveries. The role of enhanced gravity/centrifugal concentrators in recovering tungsten from ultra-fine fractions should form an important part of this aim. Reported herein are the results of investigations to improve efficiency of Wolf Minerals’ Draklends mine, a major European tungsten mine, by recovering saleable material from a magnetic waste stream of a low-intensity magnetic separator using an enhanced gravity concentrator. The mine hosts wolframite and ferberite as the main tungsten bearing mineral species. A Mozley multi-gravity separator (MGS) C-900 was selected as it is suited to exploiting small variations in mineral density to affect a separation. Working with a current manufacturer, a novel scraping blade system was tested. To assess the MGS in a statistically valid manner, a response surface methodology was followed to determine optimal test conditions. The test programme showed that the most important parameters were drum speed and wash water rate. Under optimal conditions the model predicted that 40% of the tungsten could be recovered above the required grade of 43% WO3.This work is part of the OptimOre project. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 642201. Authors are thankful to Wolf Minerals for providing material for experimentation and to Gravity Mining Ltd. for support in undertaking experiments and providing the opportunity to test the modified low profile blades