Inam Ul Ahad

Surface modification of polymers for biocompatibility via exposure to extreme ultraviolet radiation

Polymeric biomaterials are being widely used for the treatment of various traumata, diseases and defects in human beings due to ease in their synthesis. As biomaterials have direct interaction with the extracellular environment in the biological world, biocompatibility is a topic of great significance. The introduction or enhancement of biocompatibility in certain polymers is still a challenge to overcome. Polymer biocompatibility can be controlled by surface modification. Various physical and chemical methods (e.g., chemical and plasma treatment, ion implantation, and ultraviolet irradiation etc.) are in use or being developed for the modification of polymer surfaces. However an important limitation in their employment is the alteration of bulk material. Different surface and bulk properties of biomaterials are often desirable for biomedical applications. Because extreme ultraviolet (EUV) radiation penetration is quite limited even in low density mediums, it could be possible to use it for surface modification without influencing the bulk material. This article reviews the degree of biocompatibility of different polymeric biomaterials being currently employed in various biomedical applications, the surface properties required to be modified for biocompatibility control, plasma and laser ablation based surface modification techniques, and research studies indicating possible use of EUV for enhancing biocompatibility.

Characteristics and Applications of Silver Nanoparticles

This review provides an insight into the level of knowledge about the properties of silver nanoparticles, their already existing applications and possible further developments, as well as their effects on different behaviour and properties of the products wherein they are used. This chapter reviews the application fields of nanosilver, starting from basic silver properties and influential parameters in definition of silver nanoparticles (Ag NPs). Toxicity of Ag NPs is observed from various aspects in relation to cell toxicity and relevant mechanisms of their behaviour within tissue environment. Range of sizes and surface chemistry of Ag NPs and possible effects, as well as known in vivo effects are reviewed, based on the already established research results. Antibacterial properties of Ag NPs and relevant mechanisms of action are presented. Application areas where commercialization of nanosilver has started are presented: medicine (wound dressings, drug delivery, biosensors and medical diagnostics, orthopedics), food and textile industries, and water disinfection systems. Environment related issues have been considered and important conclusions derived from established results are presented. Each application sector comprises descriptions of basic mechanisms related to Ag NPs, gained benefits, but also possible risks and recognised limitations in application of Ag NPs. Future directions as recognised in specific research groups dealing with some of the sectors are listed. Exquisite properties of Ag NPs, especially antibacterial and optical properties, along with availability and lower cost of fabrication, processing and storage, compared to other noble elements makes them very promising for numerous future applications. However, proven cell toxicity must be further studied and methods to overcome these adverse effects on tissue in general are subject of current research. One important application field is drug delivery for targeted cancer cell destruction that is expected to show particular results very soon. Even with all the limitations that need to be imposed on usage of Ag NPs, they are promising nanoagent for novel advancements in different areas.

X-Ray I O Monitor Device for Primary Intensity Measurement in Computed Tomography (CT) Scanner

For a Computed Tomography (CT) Scanner used as a Non Destructive Testing (NDT) machine, 3D volume is reconstructed mathematically using un-attenuated (primary IO) and attenuated (secondary I) intensities. Primary intensity (IO) values are acquired from area of the imaging detector that is not covered by the object being tested. This procedure is prone to errors due to detector artifacts, nonlinear detector behavior, and scattered radiations detection as primary intensities, etc. This study is an attempt to make this procedure efficient and unimpeachable in which an X-ray IO monitor device is designed and validated that permit precise detection of the primary intensity to obtain better normalization and consequently higher quality image. Using TSL235 photodiode from Texas Instrument the X-ray intensity measured in current is directly converted into frequency which provides high resolution and precise X-ray detection. The device is designed to be easily integrate with an existing CT machine and could be interfaced and read out with a standard Personal Computer (PC) without any need of additional hardware. Furthermore, this device could also be used for other applications, like direct measurement of scattered radiations to apply correction to data set of scan obtained.

Response of a Zn2TiO4 Gas Sensor to Propanol at Room Temperature

In this study, three different compositions of ZnO and TiO2 powders were cold compressed and then heated at 1250 °C for five hours. The samples were ground to powder form. The powders were mixed with 5 wt % of polyvinyl butyral (PVB) as binder and 1.5 wt % carbon black and ethylene-glyco-lmono-butyl-ether as a solvent to form screen-printed pastes. The prepared pastes were screen printed on the top of alumina substrates containing arrays of three copper electrodes. The three fabricated sensors were tested to detect propanol at room temperature at two different concentration ranges. The first concentration range was from 500 to 3000 ppm while the second concentration range was from 2500 to 5000 ppm, with testing taking place in steps of 500 ppm. The response of the sensors was found to increase monotonically in response to the increment in the propanol concentration. The surface morphology and chemical composition of the prepared samples were characterized by Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). The sensors displayed good sensitivity to propanol vapors at room temperature. Operation under room-temperature conditions make these sensors novel, as other metal oxide sensors operate only at high temperature.

Application of Laser Plasma Sources of Soft X-rays and Extreme Ultraviolet (EUV) in Imaging, Processing Materials and Photoionization Studies

In the paper we present new applications of laser plasma sources of soft X-rays and extreme ultraviolet (EUV) in various areas of plasma physics, nanotechnology and biomedical engineering. The sources are based on a gas puff target irradiated with nanosecond laser pulses from commercial Nd: YAG lasers, generating pulses with time duration from 1 to 10 ns and energies from 0.5 to 10 J at a 10 Hz repetition rate. The targets are produced with the use of a double valve system equipped with a special nozzle to form a double-stream gas puff target which allows for high conversion efficiency of laser energy into soft X-rays and EUV without degradation of the nozzle. The sources are equipped with various optical systems to collect soft X-ray and EUV radiation and form the radiation beam. New applications of these sources in imaging, including EUV tomography and soft X-ray microscopy, processing of materials and photoionization studies are presented.

Laser plasma sources of soft x-rays and extreme ultraviolet (EUV) for application in science and technology

Laser plasma sources of soft x-rays and extreme ultraviolet (EUV) developed in our laboratory for application in various areas of technology and science are presented. The sources are based on a laser-irradiated gas puff target approach. The targets formed by pulsed injection of gas under high-pressure are irradiated with nanosecond laser pulses from Nd:YAG lasers. We use commercial lasers generating pulses with time duration from 1ns to 10ns and energies from 0.5J to 10J at 10Hz repetition rate. The gas puff targets are produced using a double valve system equipped with a special nozzle to form a double-stream gas puff target which secures high conversion efficiency without degradation of the nozzle. The use of a gas puff target instead of a solid target makes generation of laser plasmas emitting soft x-rays and EUV possible without target debris production. The sources are equipped with various optical systems, including grazing incidence axisymmetric ellipsoidal mirrors, a “lobster eye” type grazing incidence multi-foil mirror, and an ellipsoidal mirror with Mo/Si multilayer coating, to collect soft x-ray and EUV radiation and form the radiation beams. In this paper new applications of these sources in various fields, including soft x-ray and EUV imaging in nanoscale, EUV radiography and tomography, EUV materials processing and modification of polymer surfaces, EUV photoionization of gases, radiobiology and soft x-ray contact microscopy are reviewed.

EUV ablation: a study of the process

An investigation on short-wavelength ablation mechanism of poly(1,4-phenylene ether ether-sulfune) PPEESand poly (1-hexadecene-sulfone) PHDS (Figure 9-10) by EUV radiation is presented. The goal of this work is to evaluate the ablation behavior with respect to the influence of wavelength, fluence and quantum efficiency. Because there is no yet a general EUV ablation theory, data are analyzed in order to underline regularity of the process which can be used in future to detect the scaling laws of the process. The differences with longer wavelengths ablation and EUV one are pointed out and possible applications of EUV ablation are proposed.

Introduction—The Current Status and Momentum in Nanotechnology Commercialisation

Everybody is talking about nanoscience and nanotechnology. Nowadays ‘nano’ is very popular in science and technology, as well as in everyday news in journals, magazines and newspapers. If you ask non-scientific people “What is nano?”, the majority would probably respond “something small and new”… We can use some of the definitions, starting from Feynman’s famous sentence, “There’s Plenty of Room at the Bottom” or some officially adopted such as “Nanotechnology is science, engineering, and technology conducted at the nanoscale, which is about 1 to 100 nm.”, USA National Nanotechnology Initiative. Today, the term nano has become more than this simple definition. It is probably also becoming a kind of philosophy, as once in ancient Greece, philosophy was the science comprising mathematics, biology and other fields of natural science.

Modification of Polymer Substrates with Extreme Ultraviolet - Potential Application in Cancer Cell Identification

Conformal Invariance and Conserved Quantities for Lagrange Equation of Thin Elastic Rod Peng Wanga,∗, Hui-Rong Feng and Zhi-Mei Lou School of Civil Engineering and Architecture, University of Jinan, Jinan, Shangdong, 250022, P.R. China College of Transportation and Civil Engineering, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, P.R. China Department of Physics, Shaoxing University, Shaoxing, Zhejiang, 312000, P.R. China

TiO2 gas sensor to detect the propanol at room temperature

Titanium dioxide (TiO2) was used as raw material to create sensing materials for gas sensor applications. The sample was mixed with isopropanol and wet-ball milled for 24 hours and then dried at 120°C to evaporate the solvent. Twenty grams of the dried powder was then pressed at 2 tons (27.58 MPa) using a pellet die. The pellet was heated at 1250°C in air for 5 hours and then milled for 10 minutes to powder form using a Gy-RO Mill machine. FIB and SEM analysis were used to study the microstructure of the materials. The polyvinyl butyral (5 wt.%) was used as a binder, while ethylenglycolmonobutylether served as a solvent to make a suitable paste. The paste was screen-printed on top of an alumina substrate that had copper electrodes to form the sensor. The sensor was used to detect propanol at room temperature over two different ranges (500 to 3000 ppm and 2500 to 5000 ppm). It was observed that the response of the device increased proportionally with increasing gas concentration repeatability.