Maskless etching of silicon using patterned microdischarges

Microdischarges in flexible copper-polyimide structures with hole diameters of 200 µm have been used as stencil masks to pattern bare silicon in CF4/Ar chemistry. The discharges were operated at 20 Torr using the substrate as the cathode, achieving etch rates greater than 7 µm/min. Optical emission spectroscopy provides evidence of excited fluorine atoms. The etch profiles show a peculiar shape attributed to plasma expansion into the etched void. Forming discharges in multiple hole and line shapes permits direct pattern transfer in silicon and could be an alternative to ultrasonic milling and laser drilling

High-pressure micro-discharges in etching and deposition applications

High-pressure micro-discharges are promising sources of light, ions, and radicals and offer some advantages in materials processing applications as compared to other more conventional discharges. We review here results from etching experiments using stencil masks where the discharge is formed only in the pattern cutout. The mask consists of a thin metal-dielectric structure and is pressed against a Si wafer, which becomes part of the electric circuit. Pattern transfer takes place, albeit the profile shape appears to be limited by the expansion of the plasma into the etched hole at long etch times. We also review experiments on using micro-discharges as sources of radicals for materials deposition applications. In the latter case, the micro-discharges form in metal capillary tubes permitting incorporation of gas flow and a short reaction zone that can be controlled to favour production of specific radicals. We demonstrate these concepts by using CH4/H2 chemistry for diamond deposition on a heated Mo substrate. Good quality micro- and nano-diamond crystals could be produced

Hollow cathode sustained plasma microjets: Characterization and application to diamond deposition

Extending the principle of operation of hollow cathode microdischarges to a tube geometry has allowed the formation of stable, high-pressure plasma microjets in a variety of gases including Ar, He, and H2. Direct current discharges are ignited between stainless steel capillary tubes (d = 178 µm) which are operated as the cathode and a metal grid or plate that serves as the anode. Argon plasma microjets can be sustained in ambient air with plasma voltages as low as 260 V for cathode-anode gaps of 0.5 mm. At larger operating voltage, this gap can be extended up to several millimeters. Using a heated molybdenum substrate as the anode, plasma microjets in CH4/H2 mixtures have been used to deposit diamond crystals and polycrystalline films. Micro-Raman spectroscopy of these films shows mainly sp3 carbon content with slight shifting of the diamond peak due to internal stresses. Optical emission spectroscopy of the discharges used in the diamond growth experiments confirms the presence of atomic hydrogen and CH radicals

Microbiological Assessment of Food Quality

Microbiological quality assessment is an integral part of any product development as it gives a clue to the safety and keeping quality of the food. The studies include raw materials, on-line studies to nomitor processing, finished product and storage studies. Methodologies are also examined to develop and suggest newer and better methods. Future priority areas of work are also discussed

Argon excimer emission from high-pressure microdischarges in metal capillaries

We report on argon excimer emission from high-pressure microdischarges formed inside metal capillaries with or without gas flow. Excimer emission intensity from a single tube increases linearly with gas pressure between 400 and 1000 Torr. Higher discharge current also results in initial intensity gains until gas heating causes saturation or intensity drop. Argon flow through the discharge intensifies emission perhaps by gas cooling. Emission intensity was found to be additive in prealigned dual microdischarges, suggesting that an array of microdischarges could produce a high-intensity excimer source

Primjena novih metoda kontrole patogenih oblika bakterije Escherichia coli

Among foodborne pathogens, diarrhoeagenic Escherichia coli is of major concern because of its commensal status, abundance in the natural environment, and ability to acquire virulence determinants by horizontal gene transfer from other microbes. From enterotoxigenic E. coli (ETEC) strains to the more virulent enterohemorrhagic E. coli (EHEC), the mechanisms of pathogenicity within this species are intriguing. Recent advances in molecular diagnostics are providing novel tools for improved rapid detection and quantification of this and other pathogenic bacteria from clinical, food, and environmental specimens. These include simple and inexpensive colorimetric and immunological methods to more elaborate nucleic acid-based assays that combine extreme specificity to unparalleled sensitivity and high sample throughput. This review summarizes the current state of E. coli pathogenesis with emphasis on the need for incorporating detection and surveillance tools as part of pre- and post-harvest food safety ideals.Patogena bakterija Escherichia coli, koja uzrokuje dijareju, najopasniji je patogeni mikroorganizam u hrani zbog svoje rasprostranjenosti u prirodnom okolišu i sposobnosti prisvajanja virulentnosti horizontalnim transferom gena iz drugih mikroba. Mehanizmi njezine patogenosti su intrigantni, počevši od enterotoksigenog soja E. coli (ETEC) pa sve do virulentnijeg eneterohemoragijskog soja (EHES). Napredak u molekularnoj dijagnostici doveo je do razvoja novih metoda brzog određivanja prisutnosti i broja te bakterije i sličnih patogenih bakterija u kliničkim uzorcima, hrani i okolišu. U tu svrhu mogu se primijeniti jednostavne i jeftine kolorimetrijske i imunološke metode ili kompliciranije metode dokazivanja nukleinskih kiselina koje su vrlo specifične i osjetljive pa se pomoću njih može analizirati veliki broj uzoraka. Ovaj revijalni prikaz donosi pregled patogeneze E. coli, a ističe nužnost određivanja njezine prisutnosti te nadzor prije i nakon žetve radi procjene zdravstvene ispravnosti hrane

Is the project management field suffering from methodological inertia? Looking for evidence in publications in a recently established journal

Project management (PM) researchers have traditionally used quantitative methods in their research due to the origins of this practice-based discipline in defence and engineering. Although qualitative methods are starting to be used in PM research, most of the qualitative research reported tends to use case studies. Recently, there has been a call for PM researchers to use more novel methods to increase the variety of methods used by the researcher in the field contributing to its further development (Drouin, Muller and Sankaran 2013; Cameron, Sankaran and Scales 2015). A review of papers presented at the International Research Network on Organizing by Projects (IRNOP) conference in Berlin in 2009 showed a surprising trend that papers presented at these conferences used more qualitative methods in comparison with articles published in key PM journals. This paper analyses articles published over the past six years in a comparatively new PM journal, since its inception, to explore whether the new journal has motivated PM researchers to overcome their methodological inertia and broaden the variety of research methods they use. A mixed methods prevalence study was undertaken on articles published in the International Journal of Managing Projects in Business (IJMPiB) from 2008 to 2014 (n=265). The findings point to methodological inertia in the majority of research but also an unusually high proportion of the use of mixed methods. Future research is needed to add finer granularity to the analysis