Short Rinse Research Articles

Elimination of epidermal wax from explants increases growth in tissue culture of lily

The aerial parts of plants are covered by the cuticle, a skin containing among others waxes. The cuticle inhibits the outflow of compounds, in particular water, from the plant to the environment, and without a cuticle, plants dehydrate rapidly. In the cuticle, waxes are the chief actors in the blocking. In tissue culture, the humidity in the headspace is very high (close to 100 %) so evaporation is limited and the cuticle is less needed. The cuticle also inhibits the entry of compounds from the environment into plants. In tissue culture, the inflow of medium components occurs predominantly via wounds, primarily those made when explants are cut. The removal of the barrier is expected to enhance the uptake of medium components. This paper addresses the question as to whether the removal of the epidermal inflow barrier enhances growth in tissue culture of lily. Waxes were removed from scale explants by a short rinse (5 s) with chloroform. During this rinse, the stomata had to be closed since otherwise the tissue was severely damaged by the inflow of chloroform into the cavities below the stomata. The closure was achieved by an abscisic acid (ABA) pre-treatment. Removal of wax resulted in increased growth (50 %) relative to nonchloroform-treated explants. This procedure is, however, not suitable for practical application because the benefit was undone by an inhibitory effect of the ABA pre-treatment. The ABA pre-treatment also increased the percentage of contaminated cultures, probably because during surface-sterilization the disinfectant did not reach the contaminants inhabiting the cavities below the stomata when the stomata had been closed.

Comparison of Inorganic and Organic Acid Etching Processes on Germanium(100)

Germanium is currently used in semiconductor devices alloyed with silicon and shows promise as an alternative material which could eventually replace silicon. One challenge associated with implementing germanium is rapid oxidation after cleaning, which results in degraded electrical performance because germanium oxides contain many defects. Optimization of cleaning and etching processes are critical to the development of devices based on Ge. This study compares the use of inorganic and organic acids to etch germanium oxides, such as Ge(+1)2O, Ge(+2)O and Ge(+4)O2. X-ray photoelectron spectroscopy (XPS) was used to characterize the Ge(100) surface composition after hydrochloric and citric acid treatments. Immersion in concentrated HCl (12 M) completely removed both GeO2 as well as sub-stoichiometric oxides. The surface remained oxide free when etched inside an Ar purged glovebox attached to an XPS chamber, but suboxides were detected within 3 minutes when samples were exposed to air. A short immersion (60 s) in 2.4 M citric acid in ambient conditions yielded a visible film on the surface even after drying. Two rinse strategies were employed to remove residual citric acid from the surface. After a short rinse (30 s) in ethanol peaks attributed to carboxylic acid were detected in the C 1s XPS region. Residual citrate species were minimized by sonication in ethanol, however citrate species were still detected. Germanium surfaces etched in HCl showed less oxide and adsorbed carbon than those etched in citric acid however both surfaces are unstable in air and suboxides form readily. We investigated the two different acid cleans before passivation of the surface with sulfur.

Influence of storage and pre-sowing treatment of southern sweet-grass seeds on their germination and initial growth of seedlings

Summary Introduction: Southern sweet-grass (Hierochloë australis /Schrad./ Roem. et Schult., Poaceae) is a perennial tuft-grass occurring in North-Eastern part of Europe. Its leaves are collected from wild growing plants as an aromatic raw material used in alcohol industry. Due to overharvest, attempts to introduce the plant into cultivation have been undertaken. Objective: This work aims to assess the influence of southern sweet-grass seeds (spikelets) storage and pre-sowing treatment on their germination and the initial growth of seedlings. Methods: The seeds were assessed directly after harvest and after 6, 18 and 30 months of storage. The investigated parameters, i.e. 1000 seed weight, moisture content, germinability and viability of seeds (tetrazoline test) were determined according to ISTA. Results: After 30 months of storage, the germinability of seeds decreased from 42.6 (after harvest) to 4.6% but their viability remained high (70.9%). Stratification, short rinse of stratified seed in H2SO4 and application of KNO3 or GA3 had increased the seeds germination (over 70%). Conclusion: Southern sweet-grass seeds become dormant shortly after maturing. The improvement of germination requires the application of combined treatments, i.e. stratification, scarification and growth-promoting substances.

Aquatic Biofouling Prevention by Electrically Charged Nanocomposite Polymer Thin Film Membranes

Electrically conductive polymer-nanocomposite (ECPNC) tight nanofiltration (NF) thin film membranes were demonstrated to have biofilm-preventing capabilities under extreme bacteria and organic material loadings. A simple route to the creation and application of these polyamide-carbon nanotube thin films is also reported. These thin films were characterized with SEM and TEM as well as FTIR to demonstrate that the carbon nanotubes are embedded within the polyamide and form ester bonds with trimesoyl chloride, one of the monomers of polyamide. These polymer nanocomposite thin film materials boast high electrical conductivity (∼400 S/m), good NaCl rejection (>95%), and high water permeability. To demonstrate these membranes' biofouling capabilities, we designed a cross-flow water filtration vessel with insulated electrical leads connecting the ECPNC membranes to an arbitrary waveform generator. In all experiments, conducted in highly bacterially contaminated LB media, flux tests were run until fluxes decreased by 45 ± 3% over initial flux. Biofilm-induced, nonreversible flux decline was observed in all control experiments and a cross-flow rinse with the feed solution failed to induce flux recovery. In contrast, flux decrease for the ECPNC membranes with an electric potential applied to their surface was only caused by deposition of bacteria rather than bacterial attachment, and flux was fully recoverable following a short rinse with the feed solution and no added cleaning agents. The prevention of biofilm formation on the ECPNC membranes was a long-term effect, did not decrease with use, and was highly reproducible.

Deciduous tree leaves in trace elements biomonitoring: A contribution to methodology

Air quality biomonitoring using plant leaves has been widely applied to assess the effects of atmospheric pollution. Although practiced for many years, it has not given completely satisfactory data, due to different and even opposing results. This study comprises an investigation on the content of some trace elements (Al, As, Ba, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Cd, Pb) in leaves of four tree species common for the urban area of Belgrade (Serbia). The assay took place in July 2009 when the selected trees ( Acer platanoides, Aesculus hippocastanum, Betula pendula, Tilia cordata) were in the maximum of physiological activity during the vegetation season. Among the investigated species, leaves of A. platanoides contained the highest concentrations of the measured elements. The assumption that a large green area in the Belgrade city periphery would be a suitable control site appeared to be disputable due to the substantial load of the elements obtained in the leaves. It was shown that even a short rinse with bidistilled water (3–5 s), applied twice to the leaves prior to chemical analysis, led to a significant decrease of some element concentrations (most pronounced for Al, Fe and Pb in all species, but also evident for Cu, Cr, Co and Zn for some of them). However, by washing leaves, the representativeness of leaf samples per studied site could be improved due to removal of some superficial loosely adhered impurities and so diminished large variability of element concentrations among leaf subsamples providing more representative information on the element content in leaves per site, and the area, respectively.

Effect of Radical Scavenger and UV Irradiation on Removal of Photoresist and BARC using Water/Ozone in Cu/Low-k Interconnect

This study focused on the removal of post-etch photoresist (PR) and bottom anti-reflection coating (BARC) layers using O3 dissolved in H2O at 60 {degree sign}C. A complete removal of the PR layer was achieved with a short rinse in propylene carbonate (PC). However, the k-value of the film as determined using Hg-probe showed an increase of about 0.3 due to the wet process at 60 {degree sign}C for 5 min, and the BARC layer remained on the substrate. Using acetic acid (HAc) 0.5 M, a radical scavenger, as additive resulted in a small reduction in k-value of about 0.2 with respect to the sample processed in the same solution without HAc. Within the range of HAc concentration of 0.01-0.5 M, there was no clear trend and no significant effect in terms of PR removal as a function of HAc concentration, indicating a direct O3 attack of PR. The issue of BARC removal was addressed using UV treatment at 222 nm wavelength.

Phospholipase C-ϵ Augments Epidermal Growth Factor-dependent Cell Growth by Inhibiting Epidermal Growth Factor Receptor Down-regulation

The down-regulation of the epidermal growth factor (EGF) receptor is critical for the termination of EGF-dependent signaling, and the dysregulation of this process can lead to oncogenesis. In the present study, we suggest a novel mechanism for the regulation of EGF receptor down-regulation by phospholipase C-epsilon. The overexpression of PLC-epsilon led to an increase in receptor recycling and decreased the down-regulation of the EGF receptor in COS-7 cells. Adaptor protein complex 2 (AP2) was identified as a novel binding protein that associates with the PLC-epsilon RA2 domain independently of Ras. The interaction of PLC-epsilon with AP2 was responsible for the suppression of EGF receptor down-regulation, since a perturbation in this interaction abolished this effect. Enhanced EGF receptor stability by PLC-epsilon led to the potentiation of EGF-dependent growth in COS-7 cells. Finally, the knockdown of PLC-epsilon in mouse embryo fibroblast cells elicited a severe defect in EGF-dependent growth. Our results indicated that PLC-epsilon could promote EGF-dependent cell growth by suppressing receptor down-regulation.

A Human Protein Atlas for Normal and Cancer Tissues Based on Antibody Proteomics

Antibody-based proteomics provides a powerful approach for the functional study of the human proteome involving the systematic generation of protein-specific affinity reagents. We used this strategy to construct a comprehensive, antibody-based protein atlas for expression and localization profiles in 48 normal human tissues and 20 different cancers. Here we report a new publicly available database containing, in the first version, approximately 400,000 high resolution images corresponding to more than 700 antibodies toward human proteins. Each image has been annotated by a certified pathologist to provide a knowledge base for functional studies and to allow queries about protein profiles in normal and disease tissues. Our results suggest it should be possible to extend this analysis to the majority of all human proteins thus providing a valuable tool for medical and biological research.

Leaf surface wax layers of Brassicaceae lack feeding stimulants for Phaedon cochleariae

AbstractNumerous reports have indicated that glucosinolates are important stimulants for specialist herbivores feeding on Brassicaceae, and that these metabolites might be present on the plant surface and thereby detectable by an alighting insect. We investigated the outermost layer of leaves of two species of Brassicaceae, Brassica napus L. var. ‘Martina’ and Nasturtium officinale R. Br., using two highly selective extraction methods. When the epicuticular wax layer was mechanically removed with gum arabic, no glucosinolates were detectable in the lower and upper leaf surfaces. Extracting the leaf surfaces with a threefold short rinse with chloroform/methanol/water (2 : 1 : 1 vol/vol/vol) led to varying results, depending on the light conditions under which plants had been kept in the period prior to extraction. In plants kept under light, glucosinolates were detectable in a first extraction in minor concentrations, with increasing amounts in a second and third extraction. In plants kept in darkness, glucosinolates were almost absent in the first extraction. We postulate that the polar glucosinolates are washed from the inner leaf tissue through open stomata to the outside during solvent extraction, but are not naturally present in the outermost wax layer. The response of the crucifer specialist Phaedon cochleariae (F.) (Coleoptera: Chrysomelidae) to leaf surfaces of the host plants B. napus and N. officinale and to a glucosinolate was tested. Adults preferred both the adaxial and abaxial leaf surfaces of host plants that had been treated with gum arabic in order to remove the epicuticular waxes over intact surfaces. Waxes may therefore prevent direct contact with the stimulants. Sinigrin (allyl glucosinolate) and/or surface extracts of N. officinale leaves applied on Pisum sativum leaf discs did not evoke feeding, but feeding did occur when total leaf extracts of B. napus or N. officinale were applied on this non‐host. We conclude that glucosinolates might only act as feeding stimulants for P. cochleariae in concert with compounds other than surface waxes.

Enzymatic Cleaning of Milk Pasteurizers

The use of cleaning agents containing enzymes to reduce the (non-biodegradable) chemical loading of cleaning effluents from milk pasteurizer heat exchangers was investigated on the laboratory and plant scale. In the laboratory trials, an acid treatment (15 min, 0.5% nitric acid, 60°C) was followed by a short rinse with fresh water and then enzymatic treatment (45 min). Temperature and pH ranges were adjusted to the optimum conditions specified by the enzyme manufacturer. Deposit-free metal surfaces were obtained with three enzymes (Savinase ® , Properase 1600 L ® and Esperase ® ). The Savinase ® agent was subsequently used in a field test featuring a milk pasteurizer (ZE 23 WP1, 25,000 l h –1 , Alfa-Laval). Process conditions were matched to the laboratory conditions. After a short final rinse, the heater was opened and visual examination indicated that all surfaces in contact with the product were clean. After one week's fouling/cleaning cycles the surfaces, including the separator, were still clean. These studies indicate that enzyme-based cleaning of milk heaters can be effective. The considerable environmental benefits offered by enzyme cleaners can be realized if some of the remaining difficulties concerning enzyme dosage, process control and economics can be overcome.

Arsenic removal using a polymeric/inorganic hybrid sorbent

A fixed-bed sorption process can be very effective in removing trace concentrations of arsenic from contaminated groundwater provided: the sorbent is very selective toward both As(III) and As(V) species; the influent and treated water do not warrant any additional pre- or post- treatment; pH and composition of the raw water with respect to other electrolytes remain unchanged besides arsenic removal, and the sorbent is durable with excellent attrition resistance properties. In addition, the sorbent should be amenable to efficient regeneration for multiple reuse. This study reports the results of an extensive investigation pertaining to arsenic removal properties of a polymeric/inorganic hybrid sorbent. Each hybrid sorbent particle is essentially a spherical macroporous cation exchanger bead within which agglomerates of nanoscale hydrated Fe oxide (HFO) particles have been uniformly and irreversibly dispersed using a simple chemical–thermal treatment. The new sorbent, referred to as hybrid ion exchanger or HIX, combines excellent mechanical and hydraulic properties of spherical polymeric beads with selective As(III) and As(V) sorption properties of HFO nanoparticles at circum-neutral pH. Comparison of the results of fixed-bed column runs between the new sorbent and the polymeric anion exchanger confirmed that both As(V) and As(III) were removed very selectively with HIX. Equally important, no pH adjustment, pre- or post-treatment was warranted. Besides the absence of arsenic, the treated water composition was identical to that of influent water. HIX was amenable to efficient in situ regeneration with caustic soda and could subsequently be brought into service following a short rinse with carbon dioxide sparged water. During fixed-bed column runs, intraparticle diffusion was identified as the primary rate-limiting step for both As(III) and As(V) sorption. Repeated use of the same HIX particles during various laboratory investigations provided strong evidence that the new sorbent possesses excellent attrition resistance properties and retains its arsenic removal capacity over cycles.

Ballistic electron emission microscopy study of barrier height inhomogeneities introduced in Au/n-Si Schottky contacts by a HF pretreatment

The distribution of Schottky barrier heights over the contact area in Au/n-Si diodes was determined by ballistic electron emission microscopy. For samples on which an aqueous HF pretreatment of the Si substrate was applied, the histogram contains several high barrier Gaussian distribution components. After a short rinse, in de-ionized water or methanol, it was mainly the most important lower Gaussian component which was left. Using additional x-ray photoemission spectroscopy and atomic force microscopy measurements allowed us to propose a model, wherein negatively charged species containing F at the interface, are thought to be responsible for the high barrier Gaussian components.

Hybridisation techniques on gridded high density DNA and in situ colony filters based on fluorescence detection.

Hybridisation techniques on gridded high density DNA and in situ colony filters based on fluorescence detection.

3H]muscimol binding of GABA receptors in the visual cortex of normal and monocularly deprived cats

In vitro receptor binding techniques were used to compare the total number, affinity and regional distribution of GABA receptors in visual cortex, as revealed by [ 3H]muscimol binding, in 5 normal and 5 monocularly deprived (MD) cats. Analysis of saturation kinetics and pharmacological specificity indicated that binding was to a single site having the characteristics of the GABA A receptor. No differences were found between normal and MD cats in either number or affinity of receptors. Within visual cortex, there were laminar differences in the density of binding, but no evidence for a lateral (columnar) organization. Label was densest in the superficial layers (I–IV), lowest in layer V and intermediate in layer VI. This pattern of label varied with incubation parameters with layer IV showing the densest label when high concentrations of [ 3H]muscimol and short rinse times were used. There were no differences between normal and MD cats in regional distribution of receptors under any incubation condition.

The synthesis and biological properties of 8-azido-N 6-benzyladenine, a potential photoaffinity reagent for cytokinin

A cytokinin photoaffinity reagent, 8-azido-N (6)-benzyladenine (8N3BA), was synthesized from 8-bromoadenosine via azide replacement, benzylation at N-1, rearrangement to the N-6-benzyl derivative and acid hydrolysis. The compound thus obtained was found to have full cytokinin activity in the moss and tobacco cell-suspension bioassays. Photolysis of 8N3BA was accomplished with long and short-wavelength ultraviolet light and produced compounds which had very little or no biological activity in the two bioassays. In-vivo photolysis of 8N3BA caused loss of the cytokinin activity of this compound in moss protonemata. This result was similar to earlier ones where the biological response of moss protonemata to benzyladenine was reversed following removal of the hormone by a short rinse with water.

The interaction of apurinic acid aldehyde groups with pararosaniline in the Feulgen-Schiff and related staining procedures.

The equilibrium reactions involved in the formation of the apurinic acid (APA)-Schiff chromophores in the staining phase of the Feulgen-Schiff reaction do not allow a quantitative conversion of APA to these chromophores. By modification of the sulfite and dye concentrations and the pH of the staining reagents, or by using better solvents for pararosaniline like acetic acid or dimethylsulfoxide (DMSO) a shift of these equilibria was attempted in order to obtain a higher amount of APA-bound dye. A 40% higher absorbance, when compared with the normal Schiff-staining, was obtained in model films by staining with a saturated solution of pararosaniline in a 1:1 v/v mixture of DMSO and SO2-water, followed by rinsing in SO2-water. A doubling of the absorbance resulted in the same objects when a saturated solution of pararosaniline in a 2 M acetic acid/acetate buffer of pH 4.45 was used for staining, followed by a short rinse in SO2-water. Amino groups (as found in histones) are shown to compete with the amino groups of pararosaniline for the APA aldehydes. This effect, although causing lower staining intensities, is shown not to be the explanation for the differences in stain content found between more and less compact forms of chromatin. Depending on the pH, and dye and sulfite concentrations of the staining reagents, the following components are considered as possible contributors to the mixture of chromophores (Duijndam et al., 1973 b) formed between APA and Schiff's reagent or its modifications: 1. An acid labile component with a wavelength of maximal absorbance (lambda max) near 510 nm; its structure is probably the azomethine--CH=N--; 2. A relatively acid stable component with a high value of molecular absorbance (epsilon), an lambda max near 570 nm and possibly having an enamine structure--CH=CH--NH--; 3. A component with intermediate acid stability, low epsilon, and lambda max near 540 nm, and which is probably an alkylsulfonic acid --CH(SO3H)--NH--compound. Small differences in the staining conditions in the histochemical application of the Feulgen-Schiff reaction may cause a shift in the ratio between especially components 2 and 3, resulting in variations in stain content and in lambda max.