Alkaline protease production by Basidiobolus (N.C.L. 97.1.1): effect of 'darmform' morphogenesis and cultural conditions on enzyme production and preliminary enzyme characterization

A strain of Basidiobolus (N.C.L. 97.1.1) was isolated from plant detritus which secreted alkaline protease optimally active at pH 10.0. It is the first report of a protease from Basidiobolus, which is stable to and active under high alkaline conditions. When incubated under stationary conditions in broth cultures containing salts such as ammonium chloride, 'darmform' morphogenesis was readily induced through enlargement and internal division of the hyphal segments. Secretion of high activity alkaline protease was obtained in cultures initiated with darmform morphogenesis whereas cultures initiated from mycelial inocula grew as large pellets in submerged cultures, with little or no protease secretion. Cultural conditions favoring alkaline protease secretion have been optimized and a preliminary characterization of the enzyme is presented. Compatibility of the alkaline protease with commercial detergents as well as its potential application in recovering silver from spent photographic films have also been investigated.     

Photographic detection of fluorescent-labelled oligodeoxynucleotide in the blotting format by peroxyoxalate chemiluminescence

The preparation of a fluorescent labelled oligonucleotide and its photographic detection by peroxyoxalate chemiluminescence (PO-CL) are described. Fluorescent labelling of an oligonucleotide (15-mer) was performed with naphthalene-2,3-dicarboxaldehyde to give an N-substituted 1-cyanobenz[f]isoindole (CBI) derivative (CBI-15-mer). For the photographic detection of CBI-15-mer, the bis(2,6-difluorophenyl) oxalate (DFPO)-dimethyl phthalate (DMP) system was selected to obtain a long-lived CL emission. After optimizing the conditions for the CL reaction, the system was applied to the photographic detection, and as little as 250 fmol per spot of CBI-15-mer on a membrane were detected as a visible spot with an instant photographic film. © 1998 John Wiley & Sons, Ltd.     

Biologically produced nanosilver: Current state and future perspectives

Silver nanoparticles are one of the most commercialized nanomaterials. They are widely applied as biocides for their strong antimicrobial activity, but also their conductive, optic and catalytic properties make them wanted in many applications. The chemical and physical processes which are used to synthesize silver nanoparticles generally have many disadvantages and are not eco‐friendly. In this review, we will discuss biological alternatives that have been developed using microorganisms or plants to produce biogenic silver. Until now, only their antimicrobial activity has been studied more into detail. In contrast, a wide range of practical applications as biocide, biosensor, and catalyst are still unexplored. The shape, size, and functionalization of the nanoparticles is defined by the biological system used to produce the nanoparticles, hence for every application a specific biological production process needs to be chosen. On the other hand, biogenic silver needs to compete with chemically produced nanosilver on the market. Large scale production generating inexpensive nanoparticles is needed. This can only be achieved when the biological production system is chosen in function of the yield. Hence, the true challenge for biogenic silver is finding the balance between scalability, price, and applicability. Biotechnol. Bioeng. 2012; 109: 2422–2436. © 2012 Wiley Periodicals, Inc.     

Atomic absorption spectrophotometry applied to photographic densitometry.

For this study of photographic densitometry, sections of cartilage stained with Alcian Blue, safranin O and high iron diamine were photographed at x40 with Nikon photomicrography equipment on Kodak Panatomic X film with appropriate filters to enhance contrast. Portions of the developed negative films were selected from intercellular matrix regions, and circles of film equivalent in diameter to a 30-mu circle of tissue were obtained with a hand-held paper punch. Silver was eluted from the circles of film with 35% nitric acid, and the quantity of silver deposited on the film was determined by atomic absorption spectrophotometry as a measure of stain intensity. The intensity determined by this analytic procedure compared favorably with results obtained previously from the same tissue with microspectrophotometry. This method of silver analysis has advantages over earlier studies which used silver elution to determine photographic densitometry in its technical ease, accuracy and sensitivity. Furthermore, this method compares well with microspectrophotometry in its results and has the advantages of relative inexpensiveness and availability of equipment.     

MEASUREMENT OF PHOTOGRAPHIC QUALITY AND INDIVIDUAL DISTINCTIVENESS FOR THE PHOTOGRAPHIC IDENTIFICATION OF HUMPBACK WHALES, MEGAPTERA NOVAEANGLIAE

Accurate identification of humpback whales from photographic identification data depends on the quality of the photographs and the distinctiveness of the flukes. Criteria for evaluating photographic quality and individual distinctiveness were developed involving judgments about overall quality or distinctiveness and about specific aspects of each. These criteria were tested for the level of agreement among judges. The distinctiveness scheme was tested for the independence of distinctiveness judgments and photographic quality. Our results show that judges could agree when evaluating specific and overall aspects of photographic quality and individual distinctiveness. The level of agreement varied for different pairs of judges, and less adept judges were identified. Ability to agree on evaluations of photographic quality was independent of the experience of the judges. Overall photographic quality and overall distinctiveness were successfully predicted from more specific variables, but the agreement between judges for these was not significantly greater than the agreement for the overall measures judged directly. There was no correlation between individual distinctiveness and photographic quality for four of the five judges, but the power of this rest may be low. Analyses of photographic identification data frequently require evaluations of photographic quality and individual distinctiveness. To obtain reliable results from such analyses, evaluation schemes and judges should be tested to ensure reliable and consistent evaluations.     

Replanning and analysis of partial setup strategies in printed circuit board assembly systems

This paper considers the operation of component placement equipment for the assembly of printed circuit boards (PCBs) in a medium-volume, medium-variety manufacturing environment. It focuses on the setup management and operational planning issues associated with productive use of these expensive resources. The concept of replanning is introduced to adapt to changes in the production environment by explicitly considering the initial state of the system. The partial setup strategy is suggested as a means of efficient adaptation and as a strategy that subsumes other setup strategies encountered in practice and the literature. These concepts are applied to the optimization of a single-placement machine producing multiple products. The results of using partial setups are compared with other commonly used strategies. Experimental results suggest significant gains at the singlemachine level. Future research is being pursued to improve the solution procedures and extend these replanning concepts to the line level.     

Isolation of Sporogen-AO1, a Sporogenic Substance,from Aspergillus oryzae

Sericin is a highly hydrophilic protein family acting as the glue in Bombyx mori silk. In order to apply sericin as a wound dressing, a novel sericin film named gel film was prepared by a simple process without using any chemical modifications: sericin solution was gelled with ethanol into a sheet shape and then dried. Infrared analysis revealed that the sericin gel film contained water-stable β-sheet networks formed in the gelation step. This structural feature rendered the gel film morphologically stable against swelling and gave it good handling properties in the wet state. The sericin gel film rapidly absorbed water, equilibrating at a water content of about 80%, and exhibited elastic deformation up to a strain of about 25% in the wet state. A culture of mouse fibroblasts on the gel film indicated that it had low cell adhesion properties and no cytotoxicity. These characteristics of sericin gel film suggest its potential as a wound dressing.     

Histochemical investigations on the nature of large blood vessel endothelial and medial argyrophilic lines and on the mechanism of silver staining

Summary A study of the mechanisms involved in silver staining of blood vessels has been performed on the rabbit and rat aorta and vena cava, both in fixed and unfixed states. Pretreatment with cationic detergents, organic solvents, and solutions containing free iodide ions inhibited the silver staining. Anionic or neutral detergents, oxidizing agents, binders of such ions as Ca⁺⁺, Mg⁺⁺ and SO ₄ ^- failed to inhibit the staining. Staining of the intercellular gaps between endothelial cells and between smooth muscle cells could also be obtained if vessels were treated with a cationic detergent and bromocresol green, or by a modified Hale's colloidal iron technique. Silver lines could be returned to dechlorinated vessels, if treated with sodium chloride before silver nitrate staining, but not vice versa; by an extended treatment with dilute silver nitrate or with gold chloride following normal silver nitrate staining; and by treatment with heparin prior to silver staining. Dark chamber experiments have demonstrated that a photographic developer can take the place of light in the silver staining procedure and that a photographic fixer has the same effect on vessel silver staining as dechlorination.The obtained results have led to the hypothesis that silver staining of vessels occurs in two stages. In the first silver ions from silver nitrate are bound by polyanions located primarily in the intercellular gaps, and then reduced. This produces a network of reduced silver grains which, however, are still too sparsely aggregated to be visualized. Chloride ions in the tissues also bind and precipitate silver ions preventing their removal in subsequent rinsing procedures. In the second stage light (or a photographic developer) reduces the silver ions in silver chloride, producing a visible accumulation of metallic silver, but only around the silver grains reduced during the first stage, analogous to the photographic process.The possible existence and function of an intercellular cement substance is discussed in light of the evidence for the presence of polyanionic groups in the intercellular gaps.     

Silver nanoparticle production by the fungus Fusarium oxysporum: nanoparticle characterisation and analysis of antifungal activity against pathogenic yeasts

The microbial synthesis of nanoparticles is a green chemistry approach that combines nanotechnology and microbial biotechnology. The aim of this study was to obtain silver nanoparticles (SNPs) using aqueous extract from the filamentous fungus Fusarium oxysporum as an alternative to chemical procedures and to evaluate its antifungal activity. SNPs production increased in a concentration-dependent way up to 1 mM silver nitrate until 30 days of reaction. Monodispersed and spherical SNPs were predominantly produced. After 60 days, it was possible to observe degenerated SNPs with in additional needle morphology. The SNPs showed a high antifungal activity against Candida and Cryptococcus , with minimum inhibitory concentration values ≤ 1.68 µg/mL for both genera. Morphological alterations of Cryptococcus neoformans treated with SNPs were observed such as disruption of the cell wall and cytoplasmic membrane and lost of the cytoplasm content. This work revealed that SNPs can be easily produced by F. oxysporum aqueous extracts and may be a feasible, low-cost, environmentally friendly method for generating stable and uniformly sized SNPs. Finally, we have demonstrated that these SNPs are active against pathogenic fungi, such as Candida and Cryptococcus .     

Machine setup and component placement in printed circuit board assembly

Populating printed circuit boards is one of the most costly and time-consuming steps in electronics assembly. At the beginning of each work order, three decisions are required: (1) a sequence must be specified for placing the individual components on the board; (2) tape reels must be assigned to positions on the magazine rack; and (3) a retrieval plan must be determined should the same component type be assigned to more than one magazine slot. Collectively, these problems can be modeled as a nonlinear integer program. In this paper, we develop a series of algorithms for solving each using an iterative two step approach. Initially, a placement sequence is generated with a weighted, nearest neighbor traveling salesman problem (TSP) heuristic; the two remaining problems are then formulated as a quadratic integer program and solved with a Lagrangian relaxation scheme. As a final step, the current magazine assignments are used to update the placement sequence, and the entire process is repeated. Our ability to deal, at least in part, with simultaneous machine operations represents the major contribution of this work. The methodology was simulated for a set of boards obtained from Texas Instruments and theoretically compared with a heuristic currently in use.     

Component Partitioning Under Demand and Capacity Uncertainty in Printed Circuit Board Assembly

This paper considers the problem of configuring a printed circuit board (PCB) assembly line experiencing uncertainty in demand and capacity. The PCB assembly process involves a single line of automatic placement machines, a variety of board types, and a number of component types. The line is set up only once, at the beginning of a production cycle, to eliminate setups between board types. Using this strategy, the line therefore can assemble all different types of PCBs without feeder changes. The problem then becomes to partition component types to the different machines in the hope of processing all boards quickly with a good workload balance. In this paper, the board demands and machine breakdowns are random but follow some probability distribution, which can be predicted from past observations of the system. We formulate this problem as a stochastic mixed-integer programming formulation with the objective of minimizing the expected makespan for assembling all PCBs during a production cycle. The results obtained indicate significant improvement over the existing methods. We hope that this research will provide more PCB assembly facilities with models and techniques to hedge against variable forecasts and capacity plans     

Construction of a very high-density extracellular electrode array

Cellular activation mapping (specifying in time and space the electrical activation sequence of cells) is a well-established basic research tool in cardiac, neural, and gastric physiology. Much recent research in cardiac mapping has focused on large arrays (>200 electrodes) with small electrodes (<500 microm). Construction of such arrays using standard techniques is tedious and yields irregular electrode spacing. We present a novel construction technique that rapidly produces large arrays with regularly spaced small electrodes. For methods, fine-pitch copper ribbon cables, insulated with either polyvinylchloride (PVC) or polyimide (flexible printed circuit; FPC), were assembled together such that the active surface was the cut end of the cable. The cut end was sanded and polished, then coated with silver and sometimes silver chloride. Once completed, the alternating current (AC) root-mean-square (rms) potential was measured between two adjacent, individual electrodes. Polarization testing was conducted according to a previously reported protocol (Witkowski FX and Penkoske PA. J Electrocardiol 21: 273-282, 1988). Activation mapping was conducted in the open-chest guinea pig with both pacing- and defibrillation- strength stimuli. In terms of results, four PVC and three FPC arrays were constructed, ranging from 4 to 400 electrodes. Two hours of labor were needed to create a complete electrode array, independent of the number of electrodes, including connectors and silver/silver chloride coating. As expected, the addition of a silver/silver chloride coating significantly reduced (0.76-0.42 mV, P < 0.001) the AC rms potential difference between two electrodes. A nearly immediate recovery of the potential difference between adjacent pairs of silver/silver chloride electrodes was observed after defibrillation stimuli.     

Engineering a chemical implementation device and an imaging device for detecting chemiluminescence with a Polaroid™ high‐speed detector film: application to influenza diagnostics with the ZstatFlu®‐II test

We describe the engineering and product development of the chemiluminescent ZstatFlu®‐II Test kit for influenza diagnostics. The reaction vessel is a chemical implementation device with a polystyrene bottom chamber and a polypropylene top chamber that screw together. The patient's specimen is dispersed in a proprietary diluent and mixed inside the bottom chamber with the influenza viral neuraminidase‐specific substrate, 1,2‐dioxetane‐4,7‐dimethoxy‐Neu5Ac. Neuraminidase catalysis releases the dioxetane. The top chamber contains 40% NaOH and is sealed at the top with an ABS plastic plug‐crush pin assembly. The top chamber floor is 85% thinner at the centre, forming a frangible flap. An automated imaging device serves as an incubator for the chemical implementation devices and also facilitates the piercing of the flap by the crush pin. This action results in NaOH flushing into the bottom chamber, initiating chemiluminescence. The imaging device also exposes the Polaroid? high‐speed detector film to chemiluminescence. At the end of exposure, the film is automatically processed and ejected. Chemiluminescence from an influenza virus‐positive specimen produces a ‘+’‐shaped white image, archiving the diagnostic outcome. The modular ZstatFlu®‐II test kit components are easily adaptable for the chemiluminescent detection of a wide range of analytes. Copyright © 2003 John Wiley & Sons, Ltd.     

Growth responses and fitness costs after induction of pathogen resistance depend on environmental conditions

Fitness costs of resistance are among the most widely discussed explanations for the evolution of induced resistance, but studies on induced resistance to pathogens are scarce and contradictory. In the present study the influence of nitrogen supply, length of the growing period and competition on the seed production of Arabidopsis in response to treatment with the chemical resistance elicitor BION^® was investigated. BION^® treatment elicited resistance to the bacterial pathogen Pseudomonas syringae, and biochemical changes after BION^® treatment were similar to those observed after bacterial infection. Induced plants grew more slowly during the first week after resistance induction, for which they then compensated by exhibiting faster growth than controls. Whether or not induced plants produced less seeds than controls depended on growing conditions. Costs, no costs and even higher seed production by induced plants were observed in experiments differently combining abiotic conditions. A higher seed production by induced plants arose particularly when the vegetation period was short, most probably a consequence of senescence-related processes that had been activated by resistance elicitation. Induced plants, however, produced less seeds when competing with controls and experiencing a full growing period. Studies controlling only some of the critical environmental factors can easily lead to apparently contradictory results, which in fact represent different outcomes of a complex interplay of factors.     

Photoengraving of coverslips and slides to facilitate monitoring of micromanipulated cells or chromosome spreads

A simple photolithographic technique has been developed which can be used to produce microscopic grid patterns on glass coverslips. The grid pattern is first photo-reduced onto film, and the resulting photographic negative is then used as a mask. A glass slide or coverslip, coated with a layer of photoresist, is then exposed to tungsten light through the mask. After developing and etching, the grid pattern is transferred permanently onto glass. This simple and rapid procedure allows one to mass-produce very small, high resolution grids which are useful for monitoring individual microinjected cells or chromosomal spreads under the microscope.     

Balancing bias and precision in capture-recapture estimates of abundance

Capture‐recapture estimates of abundance using photographic identification data are sensitive to the quality of photographs used and distinctiveness of individuals in the population. Here analyses are presented for examining the effects of photographic quality and individual animal distinctiveness scores and for objectively selecting a subset of data to use for capture‐recapture analyses using humpback whale (Megaptera novaeangliae) data from a 2‐year study in the North Atlantic. Photographs were evaluated for their level of quality and whales for their level of individual distinctiveness. Photographic quality scores had a 0.21 probability of changing by a single‐quality level, and there were no changes by two or more levels. Individual distinctiveness scores were not independent of photographic quality scores. Estimates of abundance decreased as poor‐quality photographs were removed. An appropriate balance between precision and bias in abundance estimates was achieved by removing the lowest‐quality photographs and those of incompletely photographed flukes given our assumptions about the true population abundance. A simulation of the selection process implied that, if the estimates are negatively biased by heterogeneity, the increase in bias produced by decreasing the sample size is not more than 2%. Capture frequencies were independent of individual distinctiveness scores.     

The Elongation Performance of Spirulina-templated Silver Micro Springs Embedded in the Polydimethylsiloxane

Helical conductive particles have attracted much attention in preparing stretchable conductive materials because of their structural flexibility and uniform strain distribution under deformation.In this paper,Spirulina-templated silver micro springs were fabricated using electroless deposition of silver onto Spirulina surface.To investigate their potential application as conductive fillers for stretchable materials,they were mixed into polydimethylsiloxane (PDMS) uniformly,and then the mixture was spin coated on a polyfluortetraethylene (PTFE) plate to form a thin film,during which,micro springs tended to align its major axis along the radial direction of the plate.The tensile tests of micro springs were carried out using the film along the alignment direction of micro springs on the custom-made setup.Under the optimal condition of coating thickness of 0.67 μtm,helical pitch of 29 μm and annealing temperature of 300 ℃,the average elongation of micro springs can reach up to ～106.9％,which indicates that the as-prepared Spirulina-templated silver micro springs are promising flexible conductive fillers for fabricating stretchable conductive materials.     

Dry,High Resolution Autoradiography

Microtomed sections of freeze-dried, paraffin-embedded tissues are placed on pieces of thin sheet-Teflon backed by a felt pad. The sections are then pressure-mounted on dry photographic emulsion. After suitable exposure, the sections are firmly cemented to the emulsion with 0.45% cellulose acetate in a 10:1 mixture of 2-butanone and acetone. This prevents the specimens from falling off or moving during photographic processing, though the tissue can be stained through the cellulose acetate binder. The method has been tested with tissues containing tritium-labelled DNA, and it produced resolution comparable to that obtained with standard liquid emulsion or stripping film techniques.     

Dry, High Resolution Autoradiography

Microtomed sections of freeze-dried, paraffin-embedded tissues are placed on pieces of thin sheet-Teflon backed by a felt pad. The sections are then pressure-mounted on dry photographic emulsion. After suitable exposure, the sections are firmly cemented to the emulsion with 0.45% cellulose acetate in a 10:1 mixture of 2-butanone and acetone. This prevents the specimens from falling off or moving during photographic processing, though the tissue can be stained through the cellulose acetate binder. The method has been tested with tissues containing tritium-labelled DNA, and it produced resolution comparable to that obtained with standard liquid emulsion or stripping film techniques.