Immersion System Research Articles

Simulation of optical projection with polarization- dependent stray light to explore the difference between dry and immersion lithography

When imaging at high incident angles to the resist, both the reflected light from the resist surface and the image forming process of the transmitted light into the resist are polarization dependent. The transmitted TM component and the reflected TE and TM components tend to induce stray light as a function of the incident angle. In this work, these components are analyzed and evaluated quantitatively. The polarization-dependent stray light (PDS) and the system stray light found in regular optical imaging systems are incorporated into a simulation program for diffracted intensity distribution to construct exposure-defocus (E-D) trees and windows to evaluate the exposure latitude and depth of focus (DOF) of typical circuit elements. The DOF of line-space pairs and contact holes with and without PDS are compared in the cases of two- and three-beam interference, first- and second-order beams, binary intensity masks, and phase shifting masks. Even though the 193-nm immersion system is shown to be better than 157- and 193-nm dry systems, using polarized illumination can improve DOF, particularly in low k1 situations, and in other situations when the stray-light-free image contrast is low.

MASS PROPAGATION OF ECHINACEA ANGUSTIFOLIA: A PROTOCOL REFINEMENT USING SHOOT ENCAPSULATION AND TEMPORARY IMMERSION LIQUID SYSTEM

ISHS XXVI International Horticultural Congress: The Future for Medicinal and Aromatic Plants MASS PROPAGATION OF ECHINACEA ANGUSTIFOLIA: A PROTOCOL REFINEMENT USING SHOOT ENCAPSULATION AND TEMPORARY IMMERSION LIQUID SYSTEM

Benefits and limitations of immersion lithography

Liquid immersion has been used for more than 100 years to increase the numeric aperture (NA) and resolution in optical microscopy. We explore the benefits and limitations of immersion technology in lithography. Immersion optical lithography has the potential to extend the resolution below 40 nm. The theory of immersion is decribed. Simulations show that a 193-nm immersion system at NA = 0.95 can double the depth of focus as compared to a dry system. Also, an immersion 193-nm system at NA = 1.05 has slightly more depth of focus than a 157-nm dry system at NA = 0.85. However, the exposure latitude at 193 nm is decreased due to the impact of polarization in imaging. Design schemes are presented to realize an immersion step and scan system. Two configuration approaches are proposed and explored. A localized shower type solution may be preferred over a bath type solution, because the impact on the step and scan platform design is significantly less. However, scanning over the wafer edge becomes the main design challenge with a shower solution. Studies are presented that look at the interaction of immersion fluids with the lens and the photoresist. Water seems to be a likely candidate, as it does not impact productivity of the step and scan system; however, focus and aberration levels need to be carefully controlled. For 157 nm, per-fluor-polyether (PFPE) materials are currently being studied, but their characteristics may limit the productivity of the exposure system. Further research on fluid candidates for 157-nm immersion is required.

An ultrasonic wheel-array sensor and its application to aerospace structures

This paper describes the development of an ultrasonic wheel-array sensor scanning system. The system operates at 10 MHz using a 64-element array transducer which is 50 mm in length and located in a fluid-filled wheel. Thewheel is coupled to the test structure dry, or with a small amount of liquid couplant. An aperture is swept along the array forming a B-scan at each measurement position. The wheel is rolled over the surface of the test structure and a defect map (C-scan) is generated in real-time. The tyre is made from a soft, durable polymer which has very little acoustic loss. The rapid scanning is facilitated by an embedded PC which controls all of the functions of the array transmit and receive module as well as undertaking signal processing of the received waveforms. Three application studies are presented. These are the detection of embedded defects in a thick-section carbon composite test block, the detection of cracking and disbanding in a carbon composite skin-stringer sample and the inspection of sealant layers in an aluminium aircraft wing structure. In each application, the wheel-array sensor was found to produce C-scans of comparable quality to an immersion system with scanning times reduced by factors of 25-50.

TEMPERATE FRUIT PLANT PROPAGATION THROUGH TEMPORARY IMMERSION

So far many research activities have been reported on automation in micropropagation; many liquid media systems for tissue culture have been proposed in this regard. In this work the temporary immersion system (TIS) has been tested for in vitro propagation of strawberry, pear, apple, peach, cherry, plum, raspberry and papaya. Because the objectives of the experiments were to assay the media composition, to establish the immersion-period length and to define environmental parameters, a simple double bottle device, manually operated, was used. The temporary immersion of the explants was achieved filling the bottle containing the explants with the medium transferred through a silicon tube from the second bottle, in which an overpressure was created by a manual air pump. The effects on growth were compared to those of the stationary liquid and agarized cultures (control). The shoot multiplication rate was very high in strawberry, showing the typical juvenile unilobate morphology, raspberry and papaya. In pear the multiplication efficiency was strictly genotype dependent; TIS revealed to be highly efficient to prevent the apices necrosis. For the other species the TIS strongly affected the quality of the explants preventing the necrosis and the hyperhydricity. All the species maintained the juvenile habit during the TIS culture. Data on photosynthetic pigments and sugar contents seem to suggest a positive influence of TIS on the autotrophic activity.

Improved shoot regeneration from nodules of Charybdis numidica in a temporary immersion system

SummaryA procedure for improved shoot regeneration from meristematic nodules of Charybdis numidica in a temporary immersion culture system was developed by optimizing immersion frequencies, volume of the nutrient medium, and alternating application of growth regulators. Modified liquid MS medium with 3% sucrose, 20 μM BAP and 5 μM NAA (shoot induction medium) was used to induce microshoot formation on 15 g of nodules in 1000 ml bottles. Volumes of medium (250 or 500 ml) and immersion frequency (5 min every 12 or 24 h) did not significantly influence shoot regeneration rates. Shoot induction medium additionally supplemented with 5 μM paclobutrazol in most cases led to less shoots but this effect was not significant, either. Microshoots formed under these conditions were severely hyperhydrated. Nearly complete elimination of hyperhydricity and enhanced formation of properly elongated shoots were achieved by running a shoot induction step with induction medium containing paclobutrazol followed by an elongation step with a medium supplemented only with 5 μM gibberellic acid GA3. This two-step procedure yielded about 900 healthy shoots per bottle after a two-month cultivation period. Root induction was performed ex vitro during acclimatization and the plantlets could be established in the greenhouse with good success.

Growth of Lilium Oriental Hybrid ‘Casablanca’ bulblet using bioreactor culture

An automated balloon type bubble bioreactor (BTBB) was designed for the large scale propagation of lily bulblets and the factors affecting the growth of lily bulblets during bioreactor culture was studied. To establish the protocol, we used in vitro regenerated bulblets obtained from bulbscale segments of Lilium Oriental Hybrid ‘Casablanca’ as starting material. The total fresh weight as well as the individual bulblet size was markedly increased by medium refreshment. The highest number of ideal and competent bulblets (from 2 to ≥4.1 g) was achieved when bulblets were cultured in immersion system for 16 weeks with two times medium renewal after 4 and 12 weeks of culture. The sucrose concentration in the medium also plays an important role in the growth of Lilium bulblets. Larger bulblets formed on medium containing higher concentrations (90 g l −1) of sucrose. The bulblet growth in two types of BTBB: immersion and periodic immersion liquid culture (ebb & flood), was also compared. Fresh and dry weight of bulblets from the immersion system were heavier than that from the ebb & flood system. Results indicate that the immersion type BTBB with two times medium renewal is the most suitable bioreactor culture for bulblet growth of Lilium Oriental Hybrid ‘Casablanca’.

MICROPROPAGAÇÃO DE CLONES DE BANANA cv. TERRA EM BIORREATOR DE IMERSÃO TEMPORÁRIA

Mudas micropropagadas de banana têm sido ofertadas ao mercado com o intuito de suprir a demanda de uma fruticultura cada vez mais tecnificada. Os preços mais elevados deste tipo de muda têm sido um dos maiores entraves ao seu uso. Vários são os fatores que oneram o seu preço final: mão-de-obra especializada, necessidade de laboratórios bem equipados, estrutura de aclimatização apropriada, baixa taxa de multiplicação de algumas variedades, etc. O presente trabalho relata a micropropagação de bananeiras cv. Terra, utilizando biorreatores de imersão temporária, com o objetivo de aumentar a taxa de multiplicação e diminuir os custos de produção das mudas. Os resultados obtidos mostraram que o ciclo de imersão de 4 horas e a renovação do meio de cultura aos 30 dias foram essenciais para uma maior produção de biomassa e crescimento dos explantes. A composição do meio de cultura influenciou o desenvolvimento dos explantes de banana cultivados nos biorreatores. Explantes cultivados em meio MS + 3mg/L de BAP com renovação para MS básico, após 30 dias, apresentaram maior produção de biomassa e alta taxa de multiplicação. Comparando-se o biorreator de imersão temporária com o sistema tradicional em semi-sólido, observou-se que, no primeiro, as microplantas apresentaram maior comprimento, produção de biomassa de 2,86 vezes maior e 2,20 vezes mais brotos do que no sistema tradicional.

Epithelial adhesion complexes and organ culture of the human cornea

The effects of extended organ culture of human cornea on the structural integrity, particularly adhesion complexes, of the epithelium were determined. Human corneas were placed in organ culture using an immersion method. The structure of the cornea prior to culture (0 h) and at 7, 14, and 18 days in culture was evaluated by staining with hematoxylin/eosin, and by ultrastructural analysis that included a morphometric study of the type and number of adhesion complexes. Human corneas prepared immediately (0 h) and those in culture after 7 days showed similar structural organization and anatomical features. In contrast to 0 h specimens, the corneal epithelium at 14 days in culture exhibited signs of deterioration, with increases in cellular contraction, extracellular space, electron density of the cytoplasm, nuclear invaginations, and nucleoplasmic opacity, as well as aggregations of junctional complexes between cells. At 18 days in culture, the ocular surface epithelium was markedly reduced in thickness and consisted of no more than 2–3 cell layers; a distinct basal layer was not detected, and the morphology of the suprabasal and basal layers were similar. The basement membrane was disorganized, and anchoring complexes composed of hemidesmosomes were often absent. The number and type of the anchoring complexes associated with the basal epithelium and Bowman’s membrane were comparable until 14 days of age, although the total number of hemidesmosomes per μm of epithelial plasmalemma was subnormal. After 2 weeks in culture, there were 38–72% fewer anchoring complexes and a decrease of 44% in the number of hemidesmosomes/μm of membrane from samples prepared immediately and after 7 days in culture. These results indicate that the structural integrity of human corneal epithelium in organ culture is compromised after 14 days in vitro using an immersion system of tissue culture. Thus, long-term use of cultures to define homeostasis and wound healing of the ocular surface epithelium, which necessitates normal architecture including anchoring complexes between epithelium and Bowman’s membrane, may not be appropriate and requires careful monitoring both qualitatively and quantitatively at the electron microscopic level of resolution.

High-temperature, microwave-assisted UV digestion: a promising sample preparation technique for trace element analysis.

A novel, microwave-assisted, high-temperature UV digestion procedure was developed for the accelerated decomposition of interfering dissolved organic carbon (DOC) prior to trace element analysis of liquid samples such as, industrial/municipal wastewater, groundwater, and surface water, body fluids, infusions, beverages, and sewage. The technique is based on a closed, pressurized, microwave digestion device. UV irradiation is generated by immersed electrodeless Cd discharge lamps (228 nm) operated by the microwave field in the oven cavity. To enhance excitation efficiency an antenna was fixed on top of the microwave lamp. The established immersion system enables maximum reaction temperatures up to 250-280 degrees C, resulting in a tremendous increase of mineralization efficiency. Compared to open UV digestion devices, decomposition time is reduced by a factor of 5 and the maximum initial concentration of DOC can be raised by at least a factor of 50. The system's performance on a real-type sample was evaluated for the mineralization of skimmed milk (IRMM, CRM 151) and subsequent determination of trace elements using standard spectroscopic techniques. Recovery for Cd (109%), Cu (112%), Fe (99%), and Pb (96%) showed good agreement with the 95% confidence interval of the certified values.

Sugarcane micropropagation and phenolic excretion

Sugarcane shoot formation was followed using a temporary immersion system. Plant fresh weight, plant dry weight, shoot number and phenolic excretion to the culture medium were recorded during shoot formation. Shoot number increased for 30 days of culture but formation of new shoots was greatly reduced from 31 to 40 days. Phenolic excretion also increased during the first 20 days of culture (gallic acid represented 82% total phenolics) and decreased during the last 10 days (31–40 days of culture). The most intensive period of phenolic excretion (11–20 days) preceded the most intensive period of shoot formation (21–30 days). The same relationship does not seem to exist between the accumulation of fresh and dry weights. Subculture onto fresh medium at the beginning of proliferation (10 days after culture initiation) was detrimental to shoot formation in the subsequent period (11–20 days). However, such a detrimental effect could be avoided if gallic acid was added to the medium. Addition of cysteine to the culture medium reduced both excretion of phenolics and shoot formation but not fresh weight. The use of temporary immersion systems, the increase of culture medium volume per initial explant and the addition of paclobutrazol promoted both phenolic excretion and sugarcane shoot formation. Results presented here indicate a relationship between phenolic excretion and shoot formation but not with accumulation of plant weight.

High-yielding repetitive somatic embryogenesis and plant recovery in a selected tea clone, 'TRI-2025', by temporary immersion.

Methods for improving the efficiency of repetitive somatic embryogenesis and plant recovery from somatic embryos of clonal tea, TRI 2025 [Camellia sinensis (L.) O. Kuntze] were investigated by optimising the immersion frequencies of the explants using a modified temporary immersion system (TIS). The relative efficiencies of three conventional methods for multiplying embryos were compared with the temporary immersion method. The highest rate of multiplication of secondary embryos (24-fold) was achieved using the TIS. By controlling the immersion cycles, we achieved more consistent, synchronised multiplication and embryo development with a high level of plant recovery. A one-step computer-programmed immersion protocol based on a single, simple medium with no growth regulators was developed, enabling multiplication, maturation, germination and plant recovery within 17 weeks. Plantlets recovered through this method were hardy, with 2- to 5-cm-long shoots containing a minimum of 2-4 lush green leaves and a well-formed taproot. Callus formation, hyperhydricity and other developmental abnormalities were not observed at any stage in the process. Plantlets produced using this method were successfully acclimatised to glasshouse conditions. This protocol avoids culture transfers, and thus minimises the risk of contamination and reduces labour costs. This technique could have significant commercial implications in tea propagation as it has the potential for large-scale production with considerably reduced production costs.

Trend beat

Topics covered in this column include: bioaugmentation, the addition of billions of microorganisms to wastewater to achieve a range of process objectives such as improved operational efficiency and reduced levels of ammonia, grease, sludge, and odors; a new water treatment facility in Lake Havasu City, Arizona, that will be the first in the US to use biological treatment to remove manganese; an innovative and economical sidestream ozone injection system designed to disinfect drinking water in high‐pressure applications for the Greater Vancouver Water District; and, a personal immersion system (PIS) that consists of two conventional personal computers and two standard projectors with a special projection screen and interaction equipment.

Hygiene aspects of modern poultry chilling

An evaluation was made of six commercial poultry chilling systems in relation to factors affecting microbial contamination of carcasses. These systems included water immersion chilling, air chilling and air chilling with evaporative cooling using water sprays. Samples of neck skin and body cavity were taken from carcasses, together with samples from the chilling environment. These were examined for total aerobic mesophilic microbes and counts of presumptive coliform bacteria and Pseudomonas spp. at specific points in the chilling process. Physical measurements included surface and deep-muscle temperatures of carcasses, water temperatures and chlorine concentrations in the immersion system and air speed and temperature during air chilling. The results obtained for water immersion chilling confirmed previous experience that the washing effect reduces microbial contamination of carcasses, although initially the numbers of pseudomonads tended to increase. The air chillers varied in design and mode of operation, but had little overall effect on microbial contamination of the skin. When a completely dry process was used, microbial numbers were reduced approximately ten-fold in the body cavity. However, the use of water sprays tended to increase contamination of the cavity, while relatively heavy spraying using non-chlorinated water, resulted in a substantial increase in the numbers of pseudomonads.

Assessment of depuration system and duration on gut evacuation rate and mortality of red swamp crawfish

Two depuration, or purging, systems were examined for their effect on survival and evacuation rate of intestinal contents of the hindgut of crawfish ( Procambarus clarkii). In the immersion system, crawfish were held in baskets suspended in the water column and subjected to profuse aeration and low water exchange. Crawfish in the water spray system were maintained in shallow pools (1.3-cm deep water) and in a constant mist environment. Loading rate for each system was 14.5 kg crawfish/m 2 surface area. Similar mortality was observed from the two systems and averaged 9% and 12% for 24 and 48 h of purging, respectively. Cannibalism occurred in both purge systems; however, the mean net hindgut evacuation rate for crawfish was similar for the two systems and averaged 57%, 63%, 78%, and 81% for 12-, 24-, 36-, and 48-h purge durations, respectively. Evacuation efficiency after 12 and 24 h was positively correlated with water temperature. Of the total amount of intestinal contents excreted during 48 h of purging, 70%, on average, was excreted within the first 12 h. Mortality increases as purge duration increases; therefore, the shortest and most practical duration that results in a product acceptable by the consumer will be the most cost effective. A 12-h (or overnight) duration in well-managed systems may be sufficient for most markets in Louisiana.

Wave propagation in an anisotropic nickel-based superalloy

The effects of elastic anisotropy on ultrasound propagation in a nickel-based single crystal test component are studied using a 25 MHz focused probe in a water immersion system. Anisotropy gives rise to directionally dependent acoustic wavespeeds, beam steering, acoustic energy focusing and mode conversion for normal incidence. Transverse mode echoes are particularly strong in the vicinity of crystallographic directions in which the Gaussian curvature of the slowness surface is zero and divergence of the echo amplitude is predicted on the basis of the stationary phase approximation. There are other directions where the transverse mode echoes vanish for symmetry reasons. The longitudinal mode echo amplitude also shows significant variation with direction. Overall there is good agreement between the echo signal arrival times and amplitudes we measure and calculation. Progress in applying this technique to gas turbine blades is reported.

Pineapple ( Ananas comosus L. Merr) micropropagation in temporary immersion systems

A procedure for the mass propagation of pineapple plants (Ananas comosus L. Merr) using a temporary immersion technique is described. This procedure involved three distinct phases in the automated temporary immersion system: shooting, bud differentiation and elongation. To establish this protocol, we used in vitro shoots obtained from established liquid culture as starting materials. Three culture methods (solid, liquid and temporary immersion) were compared. Temporary immersion increased the multiplication rate and fresh and dry weight after 42 days. Conventional micropropagation (liquid medium) and temporary immersion were compared in combination with paclobutrazol. Paclobutrazol promoted the formation of compact bud clusters with limited leaf development. The highest multiplication rate (106) was found when ex-plants were cultured in shooting medium (MS+2.1 mg/l BA+0.3 mg/l NAA) supplemented with 1 mg/l PB for 7 weeks. A 10-l temporary immersion bioreactor was used to test two approaches during elongation stage: reduction of the shoot-formation period or decrease of the initial number of explants. The highest number of competent and uniform plants (191.8 plant/l) was achieved when shoots were cultured for 4 weeks in shooting medium supplemented with PB.

Improved production of potato microtubers using a temporary immersion system

A temporary immersion system for potato microtuber production was designed using 4-l vessels. This culture technique showed several advantages compared to solid cultures: i.e., three fold increase in shoot length, more internodes per plant and improved vigor. In the tuber induction stage, microtubers can be induced at all plant nodes, indicating that the tuberization is not restricted to specific regions. For both cultivars tested, Desiree and Atlantic, an average of 3.1 and 2.8 tubers per single node cutting was achieved after 9 weeks in culture. The size and weight of the tubers were higher than on solid media. Scale up was performed with cv. Atlantic in 10-l polycarbonate flasks and 12 units were mounted containing 150 single nodal cuttings each. An average of 2.6 tubers per inoculated cutting was obtained, with 1.3 g fresh weight per microtuber. Temporary immersion is a valuable option for potato microtuber production, as well as for shoot production during the planting season.

4Pi-Confocal Imaging in Fixed Biological Specimens

By combining the wavefronts produced by two high-aperture lenses, two-photon 4Pi-confocal microscopy allows three-dimensional imaging of transparent biological specimens with axial resolution in the 100–140-nm range. We reveal the imaging properties of a two-photon 4Pi-confocal microscope as applied to a fixed cell. We demonstrate that a fast, linear point deconvolution suffices to achieve axially superresolved 3D images in the cytoskeleton. Furthermore, we describe stringent algorithms for alignment and control of the two lenses. We also show how to compensate for the effects of a potential refractive index mismatch of the mounting medium with respect to the immersion system.

Comparative evaluation of the sporicidal activity of new low-temperature sterilization technologies: Ethylene oxide, 2 plasma sterilization systems, and liquid peracetic acid

Objective: This study was undertaken to evaluate the efficacy of 4 new low-temperature sterilization technologies: ethylene oxide with hydrochlorofluorocarbons, a liquid peracetic acid immersion system (Steris System 1 Processor), and 2 plasma sterilization processes that use vaporized hydrogen peroxide (Sterrad 100 and the Sterrad 100S). The Sterrad 100S system potentially improves sterilizer efficacy by using 2 cycles of a diffusion stage and a plasma stage per sterilization cycle. Methods: Flat stainless steel carriers were inoculated with approximately 10 6 Bacillus stearothermophilus spores. These carriers were aseptically placed in the middle of 40 cm long stainless steel lumens (hollow tubes). Two types of lumen were used: (1) a lumen test unit with a removable 5 cm center piece (1.2 cm diameter) of stainless steel sealed to the narrower steel tubing by hard rubber septums and (2) a straight lumen. Three different diameters of the lumen test unit (1, 2, and 3 mm) and a single diameter of the straight lumen (3 mm) were studied. At least 40 replicates were performed for each type of lumen and sterilization method. After inoculation, the test unit was evaluated in 1 of the low-temperature sterilization technologies. After sterilization, the carriers were cultured in trypticase soy broth for 14 days at 55°C and assessed for growth of B stearothermophilus spores. Results: Our results demonstrated that ethylene oxide with hydrochlorofluorocarbons, the Sterrad 100S, and the Sterrad 100S half cycle were highly effective in killing approximately 10 6 B stearothermophilus spores present in the center of narrow-lumen stainless steel tubes. As the lumen diameter decreased with the lumen test unit, the Sterrad 100 demonstrated reduced ability to kill B stearothermophilus spores present on the carrier. At the smallest diameter tested (1 mm), the Sterrad 100 system failed 74% of the time. The Steris System 1 was not effective in completely eliminating the 10 6 inoculum under test conditions. Conclusion: The Sterrad 100S was significantly superior to the Sterrad 100 system and equivalent to ethylene oxide with hydrochlorofluorocarbons. Introduction of this new Sterrad 100S system should improve the margin of safety and reduce processing costs by its use of a shorter cycle time. The Steris System 1 is limited by diffusion of the chemical sterilant into the interior of the lumen test unit. (AJIC Am J Infect Control 1998;26: 393-8)