0000000000035317
AUTHOR
Arnolds Ubelis
Graduate Studies of Global Change at the University of Latvia
In 2008 the University of Latvia (UL) completed an 18-month project of innovation – design, preparation and pilot-test of a 4-semester programme of trans-disciplinary graduate studies in “science, global change, and technologies for sustainable development” based on the experience the project team had acquired during 1997–2006 endorsing studies in “physics and technologies for sustainable development” and organizing two international conferences on “integrative approaches towards sustainability”. Within the project activities 25 members from faculties of natural sciences of the UL prepared and tested innovative courses of a 2 semester pilot programme comprising 4 modules, the audience being…
Iodine and mercury resonance lamps for kinetics experiments and their spectra in the far ultraviolet
Electrodeless iodine and mercury iodide radio-frequency discharge lamps have been made to provide intense sources of resonance radiation of iodine and mercury in the 183-253 nm region. Production technology and emission spectra in the ultraviolet and vacuum ultraviolet regions are described. Both lamps (iodine and mercury iodide) are designed and used for monitoring the iodine 2P1/2 (206.163 nm) and 2P3/2 (183.038 nm) level population kinetics after flash photolysis of I2 or other precursor molecules in laboratory experiments. The technique is suitable for the investigation of the gas phase reaction kinetics following the photolysis of I2 in the presence of O3.
Novel Immune TiO2 Photoluminescence Biosensors for Leucosis Detection
Abstract Novel immune photoluminescent biosensor, based on TiO2 nanoparticles, for retroviral leucosis detection has been developed. The photoluminescence spectra were excited by solid state laser with wavelength 355 nm and measured in the range of 370-800 nm. Original photoluminescence spectrum of TiO2 nanoparticles showed wide maximum at 515 nm. The biosensitive layer was formed by immobilization of retroviral leucosis antigens on the surface of TiO2 nanoparticles. Immobilization of antigens on TiO2 surface led to UV-shift of photoluminescence spectrum and increase of PL intensity. The response to different concentrations of retroviral leucosis antibodies has been measured. The decrease o…
Application of Room Temperature Photoluminescence From ZnO Nanorods for Salmonella Detection
ZnO nanorods grown by gaseous-disperse synthesis are confirmed by XRD analysis to have the wurtzite crystal structure. The obtained crystallites, as found from SEM studies, are 57 +/- 9 nm in diameter and 470 +/- 30 nm long on the average. Two emission bands of photoluminescence from ZnO nanorods observed at room temperature are centered at 376 and 520 nm. A biosensitive layer is prepared by immobilization of anti-Salmonella antibodies from liquid solutions on the ZnO surface. Immobilization of the biosensitive layer onto ZnO nanorods is found to increase the intensity of PL. After further reaction with Salmonella antigens (Ags), the PL intensity is found to decrease proportional to Ag conc…
Towards Next-Generation Small-Size Boron Ion Implanting Apparatus
Abstract The article provides a brief insight in the history of ion implantation, paying special attention to boron ion implantation in high purity Germanium crystal, exclusively valuable in the production of highly effective sensors of high-energy radiation to detect photons in the range of megaelectron-volt or higher up to hard X-ray range. There is a need for small user-friendly implanters in response to urgent demand to scale up production of short wave sensors, which are in exclusive demand for various nuclear safety systems worldwide. Particularly, research driven “high tech” small and medium enterprises in Latvia are among the three leading worldwide producers of such sensors and sys…
<title>Monitoring and analysis of air quality in Riga</title>
Riga, the capital of Latvia is a city with nearly 900,000 inhabitants and various highly concentrated industries. Air pollution in Riga is a serious problem affecting health and damaging valuable buildings of historical importance, as acid rain and smog take their toll. Therefore the Air Quality Management System with significant assistance from Swedish Government and persistent efforts from Riga City Council was arranged in Riga. It contains INDIC AIRVIRO system which simulates and evaluates air pollution levels at various locations. It then processes the data in order to predict air quality based on a number of criteria and parameters, measured by OPSIS differential absorption instruments…
Operating a cesium sputter source in a pulsed mode
A scheme is presented for pulsing of a cesium sputter negative ion source by periodically switching on and off the high voltage driving the sputtering process. We demonstrate how the pulsed ion beam can be used in combination with a pulsed laser (6 ns pulse length) that has a 10 Hz repetition rate to study the photodetachment process, where a negative ion is neutralized due to the absorption of a photon. In such experiments, where the ion beam is used only for a small fraction of the time, we show that the pulsed mode operation can increase the lifetime of a cathode by two orders of magnitude as compared with DC operation. We also investigate how the peak ion current compares with the ion c…
RF magnetron-sputtered coatings deposited from biphasic calcium phosphate targets for biomedical implant applications
Bioactive calcium phosphate coatings were deposited by radio-frequency magnetron sputtering from biphasic targets of hydroxyapatite and tricalcium phosphate, sintered at different mass % ratios. According to Raman scattering and X-ray diffraction data, the deposited hydroxyapatite coatings have a disordered structure. High-temperature treatment of the coatings in air leads to a transformation of the quasi-amorphous structure into a crystalline one. A correlation has been observed between the increase in the Ca content in the coatings and a subsequent decrease in Ca in the biphasic targets after a series of deposition processes. It was proposed that the addition of tricalcium phosphate to th…
Application of 2D Non-Graphene Materials and 2D Oxide Nanostructures for Biosensing Technology
The discovery of graphene and its unique properties has inspired researchers to try to invent other two-dimensional (2D) materials. After considerable research effort, a distinct "beyond graphene" domain has been established, comprising the library of non-graphene 2D materials. It is significant that some 2D non-graphene materials possess solid advantages over their predecessor, such as having a direct band gap, and therefore are highly promising for a number of applications. These applications are not limited to nano- and opto-electronics, but have a strong potential in biosensing technologies, as one example. However, since most of the 2D non-graphene materials have been newly discovered,…
<title>Iodine and mercury resonance lamps and their spectrum in far UV</title>
Electrodeless iodine, mercury iodide, and mercury radio- frequency discharge lamps have been made to provide effective sources of atomic spectra for analytical spectroscopy providing powerful resonance radiation of iodine and mercury in the 120-253 nm region. The lamps are required and can be used for spectral calibration, resonance absorption, and fluorescence detection techniques, for investigation of atomic characteristics (e.g., branching ratios) and other purposes where intense monochromatic spectra are needed. Production technology, development, and investigation of the UV and VUV emission are described.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downlo…
ZnO Nanorods Room Temperature Photoluminescence Biosensors For Salmonella Detection
Salmonella antibodies immobilized on ZnO nanostructures surface from liquid solutions, resulted in enhance of ZnO photoluminescence intensity. Biosensor reaction to salmonella antigens caused to decrease of PL intensity for all measured antigen concentrations.
Advanced Hardware and Software for the Upgrade of Mirror/Prisma Monochromator SPM-2 (Carl Zeiss Jena) for the Measurements of Basic Spectroscopic Properties of Atoms in Near VUV, Far UV, UV Spectral Region
Today's digital electronics and fast computers allow the efficiently processing of large volumes of spectroscopic information, which means the opportunity to reuse and upgrade monochromator with sophisticated optical and mechanical systems being designed and used in the middle of the last century. Particular interest is towards high-resolution prism monochromator. We used such an approach to computerize manual operations of universal mirror monochromator SPM-2, which has changeable quartz, glass, NaCl and KBr crystal prisms. SPM-2 was produced by VEB Carl Zeiss JENA in the early sixties of the last century (in former GDR), and its advanced features were widely used [1]. The current interest…
Specific UV and VUV spectra light sources
The report contains information about laboratory made radiofrequency powered electrodeless discharge sources (lamps) of resonance atomic spectra radiation for various elements (e.g. Hg, Cd, Zn, O, S, Se, Te, As, Sb, Bi, J, Br, Kr, Xe, H) having main spectral lines in UV and VUV region. There are known, and can be found a lot of new specific applications of such sources in laboratory made or commercial optical devices.
<title>Iodine and bromine resonance lamps in atmospheric research</title>
For the first time previously developed iodine resonance spectra source has been tested in flash photolysis experiment. Quantitative measurements of concentration kinetics of iodine atomic species in a I2+O3 system are possible. The 183.038 nm resonance absorption transition of I(2P3/2) in previously developed EDL has been studied; dependence of self-absorption and self-reversal on iodine partial pressure in the discharge volume has been measured. The search for optimal conditions for an iodine EDL with minimized self-absorption and sufficient intensity were made. In condition of flash photolysis with previously described method it is possible to determine the emission temperature, oscillat…
A Ground Validation Station for the Satellite-based Atmospheric Sensor Instruments GOME and SCIAMACHY
The development of a DOAS based ground validation station for satellite based atmospheric sensor instruments GOME and SCIMACHY at the Institute of Atomic Physics and Spectroscopy, University of Latvia, is now underway. The activity has to look to the future by: — the development of co-operation with the European research community in atmospheric science contributing to the valuable infrastructure for common needs; and — a building up of the capacity of the team (through research training of students) to become a strong partner in the future.
Production and Characterization of Oxyhydroxyapatites
The amount and alignment of hydroxyl ions influence the bioactivity of hydroxyapatite. Hydroxyl ions in hydroxyapatite are the most mobile and upon heating are the first to leave the lattice to form oxyhydroxyapatite. This work describes a method for producing hydroxyapatite with different amounts of hydroxyl ions, and reports on the changes in Fourier transform infrared absorption at increasing level of dehydroxylation. Detailed analysis of spectra in the 500 – 700 cm-1 range showed a peak shift for the hydroxyl ion absorption line at 632 cm-1 to 637 cm-1 and an increase in the wavenumber for the phosphate line at 575 cm-1.
In situ detection of atomic and molecular iodine using resonance and off-resonance fluorescence by lamp excitation: ROFLEX
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