Lignin in woody tissues after chemical pretreatment and bacterial attack

Summary Tangential latewood sections (60 m) of Scots pine sapwood were differently treated with chlorite. The subsequently incubated two strains of Bacillus polymyxa caused a weight loss up to about 25%, including a loss of lignin of about 42%.UV-microspectrophotometry of 1 m-cross-sections prepared from the cultured woody tissues demonstrated that bacteria caused neither quantitative nor qualitative changes of the remaining lignin.The lignin, which was dissociated from the pretreated woody cell wall by bacteria, could not be respired, suggesting that the lignin is a ballast to these bacteria that inhibits the dissimilation of the carbohydrates in the wood.We appreciate the financial support by Deutsche Forschungsgemeinschaft. Thanks are due to Mrs. R. Endeward for her assistance during the microspectrophotometric evaluations and to Mr. U. Engel and Dr. O. Faix for carrying out the IR-measurements     

Insektizidresistenz bei Dipteren

Zusammenfassung Einige grundsätzliche Probleme der Insektizidresistenz bei Dipteren scheinen heute geklärt zu sein. Vor allem besteht wohl kein Zweifel mehr, daß Insektizidresistenz ein genetisch verankertes Merkmal ist und daß das Insektizid bei der Entstehung einer Resistenz lediglich im Sinne eines positiven Auslesefaktors wirksam ist. Irgendwelche tatsächlich wirksamen und in der Praxis verwertbaren Möglichkeiten zur Verhütung einer Resistenzentwicklung oder ihrer erfolgreichen Bekämpfung bestehen bisher noch nicht. Der Praxis kann nur empfohlen werden, die Zahl der resistenten Individuen durch die Anwendung geeigneter Insektizidmischungen möglichst niedrig zu halten und somit der Ausbreitung der resistenten Populationen soweit wie möglich Einhalt zu bieten.

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Summary A few basic problems of resistance to insecticides in Diptera appear to be cleared. Above all there is no doubt that insecticide resistance is a genetically interrelated characteristic and that the insecticides in the origin of resistance act solely in the sense of a positive selection factor. Until now no really effective practical possibilities for the prevention of the development of resistance or its successful control do exist.In practice it can only be recommended to keep the number of resistant individuals low by employing proper insecticide mixtures and thus to check as far as possible the spread of resistant populations.

     

Incorporation of stable glycerol-borate complex into phenolic resin as a glue line treatment in engineered wood products

ABSTRACT

A glycerol-borate complex has been developed and demonstrated as a new glue line treatment for engineered wood products such as laminated veneer lumber (LVL) and plywood. This allows the entire billet or panel to be evenly penetrated with boron to elevated levels, which increases the level in the central ninth and ensures the panel is significantly higher in boron throughout the panel compared with traditional envelope treatments. These external treatment systems often result in envelope treatments as it is difficult to get the treatment chemical evenly into the central ninth of the panel. The glycerol-borate complex reported herein is compatible with phenol formaldehyde resins typically used for plywood and LVL. These resins systems are not typically compatible with boron as the boron binds to the phenolic hydroxyl groups resulting in a range of undesirable side effects, such as premature gelation of the resin system. Boron is less toxic than alternative treatment chemicals and is very effective due to its broad spectrum of fungicidal and insecticidal activity. Boron does not break down into ineffective compounds and thus does not require high treatment dose levels. Additionally, the amount added can be directly measured using ICP-MS to ensure a suitable level of treatment chemical has been added.     

Plant viruses in irrigation water: reduced dispersal of viruses using sensor-based disinfection

The increasing use of recirculating nutrient solutions and drainage water for irrigation purposes requires effective sanitation methods to minimise the dispersal of plant pathogens. Among these, plant viruses are of particular interest because they cannot be cured. A new disinfection system was tested in regard to its ability to inactivate plant viruses in nutrient solution in greenhouses. Potassium hypochlorite produced onsite by an electrolytic disinfector and injected once weekly into the nutrient solution by a sensor, prevented the dispersal of Pepino mosaic virus in the tomato crop. The management program assures that virus particles released from infected plants do not accumulate, forming an infectious virus reservoir which represents an inoculum potential in the hydroponic system. Both tested applications at 0.2 or 0.5 mg free chlorine/l nutrient solution for 60 or 30 min ensured virus inactivation and did not cause phytotoxicity. The yield of tomato plants grown in KCIO-treated nutrient solution was even significantly higher than that of control plants. PepMV-infected source plants solely bore unmarketable tomatoes showing discoloration. By inhibiting the dispersal of PepMV and the infection of test plants, the amount of unmarketable tomato fruits was reduced rigorously in treated variants.     

机动车辆新型报警器智能控制的研究

通过对机动车辆防盗报警装置使用可靠性的研究，设计了一种基于单片机控制的新型智能防盗报警器。其具有制动系统低液压报警、冷却系统冷却液高温报警、润滑系统低油压报警功能。实践证明：这种报警器可靠性强、智能程度高，使用效果优于其他报警器。     

Analysis of the retrogradation of low starch concentration gels using differential scanning calorimetry,rheology, and nuclear magnetic resonance spectroscopy

The retrogradation of 5, 10, 15, and 25% corn starch gels was measured using differential scanning calorimetry (DSC), rheology, and an array of NMR spectroscopy techniques. During the initial (<24 h) stage of retrogradation, an increase in G' corresponding to an increase in the number of solid protons participating in cross-relaxation (M(B)(0) was observed for all four concentrations studied. During the latter (>24 h) stage of retrogradation, amylopectin recrystallization becomes the dominant process as measured by an increase in deltaH(r) for the 25% starch gel, which corresponded to a further increase in. A decrease in the molecular mobility of the liquid component was observed by decreases in (17)O T(2), (1)H D(0), and T(2A). The value for T(2B) (the solid transverse relaxation time) did not change with concentration or time indicating that the mobility of the solid component does not change over time despite the conversion of the highly mobile starch fraction to the less mobile solid state during retrogradation.     

Mercury deposition and sources for the upper great lakes region

Mercury concentrations and depositions for northeastern Minnesota were measured in precipitation to investigate depositional trends, relationships with major cations and anions, and possible source emission regions. Results for 1987–1990 showed that environmentally significant amounts of Hg are present in precipitation and air and are subsequently deposited to remote lake watersheds. Volume-weighted concentrations of total Hg in precipitation averaged about 18 ng Hg L⁻¹ with calculated annual depositions near 15 μg Hg m⁻². Mercury concentrations in precipitation are positively correlated with the major ions, conductivity, and pH, and are negatively correlated with precipitation volume. The best predictor equation from stepwise regression has an r² of 0.65 with Mg and chloride concentrations as predictor variables. From measurements of Hg in rain concentrations as a function of time within events, scavenging ratios for “washable” Hg were calculated to be 140 ± 80 (mass based at a 1 mm hr ⁻¹ precipitation rate). Up to about 10% of the total Hg in air is subject to washout by precipitation for a given event. Air parcel back-trajectories indicate that possible source regions within 72-hr travel time were located mostly to the south, southeast, and southwest, up to 2500 km distance away but local sources may also be important.     

Dual stable isotope analysis (δC and δN) of soil invertebrates and their food sources

More research is required to validate and refine natural abundance stable isotope ratio techniques as a tool for the investigation of the feeding ecology of soil animals and trophic relations in soil food webs. Isotope ratios of C (δ¹³C) and N (δ¹⁵N) were measured in herbivorous and detritivorous invertebrate groups, namely lumbricid earthworms (7 species), enchytraeid worms (3 species), slugs (3 taxa), and their potential food sources in an arable system. Intrapopulation δ¹⁵N variation in the slug Deroceras reticulatum (n=52) was large (range 4.2‰), possibly reflecting spatial variability in the food sources. Significant correlations between C:N ratios and isotope ratios in earthworms suggest that factors other than feeding may influence isotopic patterns. One enchytraeid species, Enchytraeus buchholzi, was enriched in ¹³C and strongly depleted in ¹⁵N compared to all other groups. Invertebrates formed a continuum when considered in relation to C and N separately, but fell into two distinct groups on the basis of combined C and N isotope ratios. The less enriched group represents herbivorous and litter-feeding species, while the more enriched group represents soil feeders. It is concluded that δ¹³C measurements could provide a means of assigning separate baseline δ¹⁵N values to primary and secondary decomposers, which in turn could improve the inference of higher trophic levels, omnivory and intraguild predation.