Elucidating the role of ApxI in hemolysis and cellular damage by using a novel apxIA mutant of Actinobacillus pleuropneumoniae serotype 10

Exotoxins produced by Actinobacillus (A.) pleuropneumoniae (Apx) play major roles in the pathogenesis of pleuropneumonia in swine. This study investigated the role of ApxI in hemolysis and cellular damage using a novel apxIA mutant, ApxIA336, which was developed from the parental strain A. pleuropneumoniae serotype 10 that produces only ApxI in vitro. The genotype of ApxIA336 was confirmed by PCR, Southern blotting, and gene sequencing. Exotoxin preparation derived from ApxIA336 was analyzed for its bioactivity towards porcine erythrocytes and alveolar macrophages. Analysis results indicated that ApxIA336 contained a kanamycin-resistant cassette inserted immediately after 1005 bp of the apxIA gene. Phenotype analysis of ApxIA336 revealed no difference in the growth rate as compared to the parental strain. Meanwhile, ApxI production was abolished in the bacterial culture supernatant, i.e. exotoxin preparation. The inability of ApxIA336 to produce ApxI corresponded to the loss of hemolytic and cytotoxic bioactivity in exotoxin preparation, as demonstrated by hemolysis, lactate dehydrogenase release, mitochondrial activity, and apoptosis assays. Additionally, the virulence of ApxIA336 appeared to be attenuated by 15-fold in BALB/c mice. Collectively, ApxI, but not other components in the exotoxin preparation of A. pleuropneumoniae serotype 10, was responsible for the hemolytic and cytotoxic effects on porcine erythrocytes and alveolar macrophages.     

Ammonia volatilization from ammonium sulfate as sulfur source

Surface application of ammonium sulfate (AMS) as S source to soils with pH ≥7.0 is subjected to ammonia (NH₃) volatilization. However, AMS volatilizes less NH₃ than urea does. In soils with pH <7.0, unlike urea, very little NH₃ volatilization from AMS occurs. The associated N with AMS may enhance early biological N fixation by leguminous crops as compared to S sources without N such as polyhalite.     

Behavior of acoustic emission generation during tensile tests perpendicular to the plane of particleboard II: effects of particle sizes and moisture content of boards

Particleboard specimens with various particle sizes were conditioned into two ranges: low and high moisture content. One set was investigated for internal bond (IB) strength and acoustic emission (AE) events during tensile tests perpendicular to the plane and the other for ultrasonic wave transmission characteristics in the thickness direction. The particleboard structural mechanics were changed as a result of the moisture effect. Specimens conditioning to higher moisture content had lower IB strength and lower cumulative acoustic emission event counts (T _AE). The decrease in IB strength indicated that the irreversible thickness swelling was seen when recovery forces of the particles exceed the restraining action of the adhesive. This was attributed to stress release, which resulted in internal failure of the board. The change in the internal structure caused an increased stress level at the initiation of AE generation. No events were recorded before this stress level, obeying theKaiser effect. The decrease inT _AE was not only related to the decrease in IB strength but was also affected by the transformation (attenuation) of the AE signals during IB tests according to the mesh size used.Part of this paper was presented at the 45th and 50th Annual Meetings of the Japan Wood Research Society, Tokyo and Kyoto, 1995 and 2000, respectively     

大豆的一个新三体

该新三体于1983年发现,1984年鉴定。新三体的超数染色体为带随体的染色体,命名为Trisomic E(简写为 Tri E),其四体应称为随体四体(Satellite tetrasomic)。非整倍体的原始真叶较小,生长势较弱,单株结荚数比二倍体少得多。控制茸毛色的基因(t)可以定位在新三体的超数染色体上。     

Simultaneous Absorption of SO2 and NO in a Stirred Tank Reactor with NACLO2/NAOH Solutions

The wet scrubbing combined SO_x/NO removal system is one ofthe advanced air pollution control devices. This study tries tounderstand the kinetics of the absorption in the system. The absorption of SO₂ and simultaneous absorption of SO₂ and NO, whose concentrations are typical for flue gases emittedfrom coal-fired power plants, in a stirred tank reactor with NaClO₂/NaOH solutions were carried out at 50 °C.The liquid-side and gas-side mass transfer coefficients of the system were determined. The results indicate that the absorptionof SO₂ is completely gas-film controlled if the NaOH concentration is greater than 0.1 M or the NaClO₂ concentration is greater than 0.2 M. Adding SO₂ would decrease the absorption rate of NO; however, the addition of NO has no effect on the absorption rate of SO₂. The existence of O₂ has no significant effect on the absorption rate of SO₂ and NO in the combined SO_x/NO removal tests.     

Absorption Kinetics of Nitrogen Oxides using Sodium Chlorite Solutions in Twin Spray Columns

NO _X is a major pollutant that causes acid deposition and photochemical smog. A large amount of NO _X is emitted from combustion sources such as power plants. As some articles have indicated, NO _X removal with NaClO₂ solution in an absorption column is an effective control approach. In this approach, first insoluble NO is oxidized into water-soluble NO₂ under acidic conditions, then NO₂ is removed in alkaline NaClO₂ solutions. The results indicate that the reaction rate constant is 9.1×10⁴ (L)^4.4/cm⁶/s/mol^2.4 in the first absorption column with acidic conditions, and the reaction orders with respect to NO and NaClO₂ are 1.4 and 2, respectively. In the second absorption column with alkaline conditions, the reaction rate constant is 3.2×10⁷ (L)^5.2/cm⁶/s/mol^3.2 and the reaction orders with respect to NO and NaClO₂ are 1.6 and 2.5, respectively. The activation energies in the first and second absorption column are 71.8 and 139.6 kJ/mol, respectively.     

Determination of carotenoids in spear shrimp shells (Parapenaeopsis hardwickii) by liquid chromatography

The objectives of this study were to develop a high-performance liquid chromatography method for analysis of carotenoids in spear shrimp shells (Parapenaeopsis hardwickii) and to compare the extraction efficiency of carotenoids by supercritical carbon dioxide (SCD) and solvents. Results showed that the most appropriate HPLC method was accomplished by employing a Cosmosil 5C18-AR-II column and a mobile phase of methanol-dichloromethane-acetonitrile (90:5:5, v/v/v) (A) and water (100%) (B) with the following gradient elution: 92% A and 8% B in the beginning, decreased to 4% B in 9.5 min, 1% B in 26 min, 0% B in 35 min, maintained for 25 min, and returned to 92% A and 8% B in 61 min. All-trans-astaxanthin and its two cis isomers, as well as five astaxanthin monoesters and 11 diesters were resolved within 60 min with a flow rate at 2 mL/min and detection at 480 nm. Astaxanthin diesters were found to contain 12 fatty acids, of which palmitic acid and stearic acid constituted a large portion, whereas astaxanthin monoesters were found to contain 10 fatty acids with arachidonic acid dominating. Solvent extraction could generate a higher content of trans-astaxanthin and astaxanthin esters, while SCD extraction could produce greater levels of 9-cis-astaxanthin and 13-cis-astaxanthin.     

Molecular simulations to estimate thermodynamics for adsorption of polar organic solutes to montmorillonite

Ideally, one could use molecular mechanics or quantum mechanics to predict the magnitude of organic solute adsorption from water to soil minerals. Reproduction and/or prediction of mineral and interfacial structures remains challenging, but calculation of meaningful energy relations through computational chemistry techniques is even more difficult than structural calculations. This paper attempts to define the necessary and relevant components for an overall scheme that allows translation of computed interaction enthalpies to experimental adsorption enthalpies and vice versa. While the scheme could be applied to quantum calculations, we test it for the possibility of using empirical molecular mechanics to estimate relative energies for the adsorption of non‐ionic organic solutes in clay mineral‐water‐solute systems. We used molecular dynamics’ simulations to estimate relative clay–organic interaction enthalpies for a series of nitro‐aromatic solutes and hydrated, K‐saturated montmorillonite, for comparison with experimental adsorption isotherm data for the same clay‐nitroaromatic systems. The trend of computed interaction enthalpies (e.g. −234 ± 17 kJ mol⁻¹ for trinitrobenzene and −154 ± 16 kJ mol⁻¹ for p‐nitrobenzene) agreed modestly well with the trend of adsorption maxima from the experiments. Furthermore, we developed several variants on a thermodynamic cycle framework for comparing computed interaction energies with experimentally determined adsorption enthalpies. The algorithms, which include estimates for enthalpy changes both in bulk solution and in the clay interlayer, show promise: for p‐dinitrobenzene and for 1,3,5‐trinitrobenzene, the overall predicted adsorption enthalpies (e.g. −13 ± 22 and −67 ± 23 kJ mol⁻¹, respectively) were in modest agreement with experiments (−18 ± 1 and −28 ± 4 kJ mol⁻¹, respectively). We discuss shortcomings of the methods, in hopes of encouraging better estimates for the various energy terms, improvement of the algorithms, and more valid comparisons between quantum mechanical or molecular mechanical interaction energies and experimental enthalpies.