Industrial utilization of tobacco stalks II: preparation and characterization of tobacco pulp by steam explosion pulping

Our previous paper showed tobacco stalks to posses the characteristics of a raw material for pulp and paper application. It contains the major biomass constituents and cell components common to wood species. In this study, preparation and characterization of tobacco stalk pulp by steam explosion (SE) pulping at two chemical pretreatments were attempted. Chemical pretreatment prior to SE pulping improved the brightness, yield, and strength properties of the resulting tobacco SE pulps in the order: 6% Na₂SO₃ + 1% NaOH > 6% Na₂SO₃ > control (untreated). The 6% Na₂SO₃ + 1% NaOH-impregnated tobacco stalks produced SE pulps of good fiber length distribution and considerable properties that compare well with pulps from other raw materials obtained from previous studies, and the nonimpregnated ones showed strength properties superior to those of their poplar counterpart. Prior to bleaching, pretreating the tobacco stalk SE pulps with two stages, 2% NaOH at 90°C, improved the initial pulp brightness by about 5 points. Two-stage 6% H₂O₂ bleaching gave a comparable effect with hypochlorite bleaching for both tobacco and poplar, giving a 29–34 brightness point increase for tobacco SE pulp and 61 for the poplar samples. The differences in the bleaching responses for untreated tobacco and poplar SE pulps were attributed to the differences in their lignin structure, as shown in the total yield of their respective nitrobenzene oxidation products and FT-IR spectra. Tobacco SE pulps contain more of the guaiacyl-type lignin and poplar the syringyl-type lignin.This paper was presented in part during the 1998 CORESTA (Cooperation Centre for Scientific Research Relative to Tobacco) Congress, Brighton, UK, October 1998     

Lessons from the Demonstration Management Improvement Program

The Management Improvement Program,a process based on Organizational Developmentprinciples and methods, was applied to an irrigatedagricultural system in Arizona, USA. The MIP seeks toimprove management and performance of the agriculturalsystem through structured diagnosis, planning, andimplementation activities with the participation ofsystem stakeholders. An equally important objectiveof the demonstration project was to identify strengthsand shortcomings of the MIP methodology and togenerate recommendations for managing its futureapplications. The data used to analyze thedemonstration project's management were obtainedthrough formal interviews and informal conversationswith individual participants, program review andfeedback sessions, and records of meetings andindividual communications.Lessons about the project's management are categorizedin six areas: the initial exploration phase, initialplanning, participant on-boarding, formation of theprocess management team, development of the localcontrol group, and evaluation of the project. A keyaspect of conducting a change process such as the MIPfor improving the performance of agricultural systems,is that issues affecting the system may be difficultto identify early in the process or may requirelonger-term solutions, extending beyond the life ofthe formal process. Because of this uncertainty, adetailed action plan, the role of participants, andmeasures for evaluating progress or impact are alsolikely to be uncertain early in the project. Nevertheless, it is critical that the application,including these elements, be defined as concisely aspossible, especially relative to scope and funding,while still allowing the flexibility to address apotentially wider range of issues. Given the natureof the MIP, those responsible for its management needto be technically proficient, experienced with teammanagement techniques, sensitive to the localpolitical environment of natural resource management,and when necessary, willing to challenge stakeholders'initial understandings of issues.     

Colorimetric Evaluation of Mahi-Mahi and Tuna for Biogenic Amines

The Food and Drug Administration and National Marine Fisheries Services grade tuna and mahi-mahi using trained sensory panels in order to determine the quality of these fish. A major concern with both species is the presence of histamine in the flesh, which can cause scombroid poisoning, a severe illness that can lead to death. Three different assays were examined in an attempt to correlate sample grade with biogenic amine content. The first method, acetic acid Dräger tubes, was only effective in identifying the highest grade (lowest quality) of mahi-mahi. The second method was a bromophenol blue (BPB) colorimetric strip that was sensitive to volatile biogenic amines. The third method was a histamine-specific enzyme-linked immunosorbant assay (ELISA) that detected analytes in the liquid phase. The results of the BPB and ELISA methods showed a correlation between sample grade and biogenic amine content for mahi-mahi. The same correlation was not observed with the tuna samples, likely due to physiological differences between the two species that affect the detection of the analytes.     

Influence of formulants and salt formation on volatilisation and activity of pyrimethanil

Pyrimethanil is an anilinopyrimidine fungicide which is highly effective against grey mould (Botrytis cinerea) in many crops. Some of its effectiveness can be attributed to localised vapour-phase activity in parts of the canopy not reached by foliar spray. Control of pyrimethanil volatilisation was investigated using matrix-forming materials or by formation of salts using organic acids. Whilst matrix formation had little effect, organic salts of pyrimethanil showed much reduced volatility. Some of the salts showed different bio-logical potential against cereal pathogens that were not well controlled by parent pyrimethanil. In addition, salt formation offered the possibility of significant changes to the physical form of pyrimethanil, opening up new formulation and co-formulation opportunities. © 1998 Society of Chemical Industry     

Genetic engineering of maize (Zea mays) for high-level tolerance to treatment with the herbicide dicamba

Herbicide-tolerant crops have been widely and rapidly adopted by farmers in several countries due to enhanced weed control, lower labor and production costs, increased environmental benefits, and gains in profitability. Soon to be introduced transgenic soybean and cotton varieties tolerant to treatments with the herbicide dicamba offer prospects for excellent broadleaf weed control in these broadleaf crops. Because monocots such as maize (Zea mays) can be treated with dicamba only during a limited window of crop development and because crop injury is sometimes observed when conditions are unfavorable, transgenic maize plants have been produced and tested for higher levels of tolerance to treatment with dicamba. Maize plants expressing the gene encoding dicamba monooxygenase (DMO) linked with an upstream chloroplast transit peptide (CTP) display greatly enhanced tolerance to dicamba applied either pre-emergence or postemergence. Comparisons of DMO coupled to CTPs derived from the Rubisco small subunit from either Arabidopsis thaliana or Z. mays showed that both allowed production of transgenic maize plants tolerant to treatment with levels of dicamba (i.e., 27 kg/ha) greatly exceeding the highest recommended rate of 0.56 kg/ha.     

Mercury: results on mass, radius, ionosphere, and atmosphere from mariner 10 dual-frequency radio signals

Analysis of the radio-tracking data from Mariner 10 yields 6,023,600 +/- 600 for the ratio of the mass of the sun to that of Mercury, in very good agreement with values determined earlier from radar data alone. Occultation measurements yielded values for the radius of Mercury of 2440 +/- 2 and 2438 +/- 2 kilometers at laditudes of 2 degrees N and 68 degrees N, respectively, again in close agreement with the average equatorial radius of 2439 +/- 1 kilometers determined from radar data. The mean density of 5.44 grams per cubic centimeter deduced for Mercury from Mariner 10 data thus virtually coincides with the prior determination. No evidence of either an ionosphere or an atmosphere was found, with the data yielding upper bounds on the electron density of about 1500 and 4000 electrons per cubic centimeter on the dayside and nightside, respectively, and an inferred upper bound on the surface pressure of 10(-8) millibar.     

小麦农杆菌介导转基因植株的稳定获得和检测

 以预培养 4 d的小麦幼胚愈伤组织为受体 ,L B培养基上激活培养 3 d或 AB培养基上激活培养 4 d,并在WCC培养基中重悬的 C5 8c1农杆菌菌系为供体 ,将含有目的基因、标记基因的 p PTN2 4 9、p PTN 2 5 4、p PTN2 70、p SIS-GFP等重组 DNA质粒转入了小麦 ,经在含 10～ 5 0 mg/ L geneticin( G4 18)、5 0 mg/ L cefotaxime、5 0 m g/ L vancomycin、5 0 m g/ L ticillicin选择培养基上多次选择 ,移栽前利用 npt EL ISA检测 ,移栽后利用叶片离体退绿、PCR和 South-ern blot 4种方法综合检测 ,共获得了 2 9株转基因植株 ,转化频率平均为 0 .82 %。在所获得的转基因植株中 ,单拷贝整合植株占 65 .5 2 %。研究结果还表明 ,不同基因型的转化效率显著不同 ,除了 Bobwhite外 ,笔者也从扬麦 10号获得了转基因植株 ;EL ISA测定值的高低与外源 DNA整合的拷贝数有一定关系 ;初步建立了农杆菌介导稳定转化小麦的技术体系。     

Morphofunctional Characterization of Cooled Sperm With Different Extenders to Use in Equine-Assisted Reproduction

The aim of this study was to assess extenders for cooling equine semen at 5°C and to be used in assisted reproductive technologies (ARTs). Four ejaculates were obtained from each of four stallions. Gel-free semen was diluted in three different extenders: (1) SMK, an opaque skim milk–based extender; (2) SMT, a skim milk (65%) and Tyrode medium (35%); and (3) BSAG, a clear extender containing 1% bovine serum albumin. Samples were packaged (10 mL; 50 × 10⁶ sperm/mL) and stored in a cooling device at 5°C for 12 hours. Analyses were done at 0, 4, 8, and 12 hours after cooling. Semen was analyzed for sperm motility characteristics using a computer-assisted sperm analysis, for plasma membrane and acrosome integrity and mitochondrial membrane potential, using fluorescent probes (propidium iodide, Hoechst 33342, fluorescein isothiocyanate–conjugated Pisum sativum agglutinin, and 5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolyl carbocyanine iodide [JC-1]). Morphology was evaluated with differential interference contrast microscopy and sperm chromatin integrity by the toluidine blue technique. Data were analyzed by analysis of variance and by Tukey test, with time as a repeated measure (SAS, 1998), when P < .05 was significant. In general, milk-based extenders (SMT and SMK) showed improved maintenance of semen quality compared with BSAG. Finally, the addition of skim milk to equine semen extender for cooling at 5°C for 12 hours seems to play a crucial role in sperm preservation. Although, optically clearer extenders are desired for use in ARTs, such as sperm sexing, the milk-free extender (BSAG) is less efficient for cooled-stored equine semen.