The thermal fatigue resistance of vermicular cast iron coupling with H13 steel units by cast-in process

This paper focuses on improving the thermal fatigue resistance on the surface of vermicular cast iron coupling with inserted H13 steel blocks that had different cross sections, by cast-in processing. The microstructure of bionic units was examined by scanning electron microscope. Micro-hardness and thermal fatigue resistance of bionic samples with varied cross sections and spacings were investigated, respectively. Results show that a marked metallurgical bonding zone was produced at interface between the inserted H13 steel block and the parent material - a unique feature of the bionic structure in the vermicular cast iron samples. The micro-hardness of the bionic samples has been significantly improved. Thermal resistance of the samples with the circular cross section was the highest and the bionics sample with spacing of 2 mm spacing had a much longer thermal fatigue life, thus resulting in the improvement for the thermal fatigue life of the bionic samples, due to the efficient preclusion for the generation and propagation of crack at the interface of H13 block and the matrix. Crown Copyright (c) 2010 Published by Elsevier Ltd. All rights reserved.

Enhanced Thermal Shock Resistance of Ceramics through Biomimetically Inspired Nanofins

We propose here a new method to make ceramics insensitive to thermal shock up to their melting temperature. In this method the surface of ceramics was biomimetically roughened into nanofinned surface that creates a thin air layer enveloping the surface of the ceramics during quenching. This air layer increases the heat transfer resistance of the surface of the ceramics by about 10 000 times so that the strong thermal gradient and stresses produced by the steep temperature difference in thermal shock did not occur both on the actual surface and in the interior of the ceramics. This method effectively extends the applications of existing ceramics in the extreme thermal environments.

Potential role of DNA-dependent protein kinase in cellular resistance to ionizing radiation

In this paper, we study the ability of DNA-PK-deficient (M059J) and -proficient (M059K) cells to undergo the rate of cellular proliferation, cell cycle distribution and apoptosis after 10 Gy X-ray irradiation, and the role of DNA-PK in radiosensitivity. The results showed that M059J cells exhibited hyper-radiosensitivity compared with M059K cells. A strong G2 phase arrest was observed in M059J cells post irradiation. Significant accumulation in the G2 phase in M059J cells was accompanied by apoptosis at 12 h. Altogether, the data suggested that DNA-PK may have two roles in mammalian cells after DNA damage, a role in DNA DSB repair and a second role in DNA-damaged cells to traverse a G2 checkpoint, by which DNA-PK may affect cellular sensitivity to ionizing radiation. 地址: [Li Ning; Zhang Hong; Wang Yanling; Hao Jifang] Chinese Acad Sci, Inst Modern Phys, Lanzhou 730000, Peoples R China; [Li Ning; Zhang Hong; Wang Yanling; Hao Jifang] Key Lab Heavy Ion Radiat Med Gansu Prov, Lanzhou 730000, Peoples R China; [Li Ning; Wang Yanling] Chinese Acad Sci, Grad Sch, Beijing 100039, Peoples R China; [Wang Xiaohu] Gansu Tumor Hosp, Dept Radiotherapy, Lanzhou 730050, Peoples R China

Electrochemical measurement of hydrogen peroxide in plasma: Evaluation of freshwater prawn (Macrobrachium rosenbergii) and crucian carp (Cyprinus carpio) phagocytes under natural conditions

An electrochemical technique for the real-time detection of hydrogen peroxide (H2O2) was employed to describe respiratory burst activity (RBA) of phagocytes in plasma which can be used to evaluate the ability of immune system and disease resistance. The method is based upon the electric current changes, by redox reaction on platinum electrode of extracellular hydrogen peroxide (H2O2) released from phagocytes stimulated by the zymosan at 680 mV direct current (d.c.). Compared with the control, activation of respiratory burst by zymosan particles results in a high amperometric response, and a current peak was obtained during the whole monitoring process. The peak current was proved by addition Of Cu2+ and other controls, to be the result of intense release of H2O2 from phagocytes. The peak area was calculated and used to evaluate the quantity of effective H2O2, which represents the quantity of H2O2 beyond the clearance of related enzymes in plasma. According to Faraday's law, the phagocytes' ability of prawns to generate effective H2O2 was evaluated from 1.253 x 10(-14) mol/cell to 6.146 x 10(-14) mol/cell, and carp from 1.689 x 10(-15) Mol/Cell to 7.873 x 10(-1)5 mol/cell. This method is an acute and quick detection of extracellular effective H2O2 in plasma and reflects the capacity of phagocytes under natural conditions, which could be applied for selecting species and parents with high immunity for breeding in aquaculture. (c) 2007 Elsevier Ltd. All rights reserved.

Berberine as a natural source inhibitor for mild steel in 1 M H2SO4

Berberine was abstracted from coptis chinensis and its inhibition efficiency on corrosion of mild steel in 1 M H2SO4 was investigated through weight loss experiment, electrochemical techniques and scanning electronic microscope (SEM) with energy disperse spectrometer (EDS). The weight loss results showed that berbefine is an excellent corrosion inhibitor for mild steel immersed in 1M H2SO4. Potentiodynamic curves suggested that berbefine suppressed both cathodic and anodic processes for its concentrations higher than 1.0 x 10(-4) M and mainly cathodic reaction was suppressed for lower concentrations. The Nyquist diagrams of impedance for mild steel in 1 M H2SO4 containing berbefine with different concentrations showed one capacitive loop, and the polarization resistance increased with the inhibitor concentration rising. A good fit to Flory-Huggins isotherm was obtained between surface coverage degree and inhibitor concentration. The surface morphology and EDS analysis for mild steel specimens in sulfuric acid in the absence and presence of the inhibitor also proved the results obtained by the weight loss and electrochemical experiments. The correlation of inhibition effect and molecular structure of berberine was then discussed by quantum chemistry study. (c) 2005 Elsevier B.V. All rights reserved.

The ecological effects of exotic disease resistance genes introgressed into British gooseberries

Warren, J. and James, P. (2006). The ecological effects of exotic disease resistance genes introgressed into British gooseberries. Oecologia 147(1),69-75. RAE2008

Plasmid biology of natural Lactococcus lactis strains and molecular mechanisms of bacteriophage-host interaction

Lacticin 3147, enterocin AS-48, lacticin 481, variacin, and sakacin P are bacteriocins offering promising perspectives in terms of preservation and shelf-life extension of food products and should find commercial application in the near future. The studies detailing their characterization and bio-preservative applications are reviewed. Transcriptomic analyses showed a cell wall-targeted response of Lactococcus lactis IL1403 during the early stages of infection with the lytic bacteriophage c2, which is probably orchestrated by a number of membrane stress proteins and involves D-alanylation of membrane lipoteichoic acids, restoration of the physiological proton motive force disrupted following bacteriophage infection, and energy conservation. Sequencing of the eight plasmids of L. lactis subsp. cremoris DPC3758 from raw milk cheese revealed three anti-phage restriction/modification (R/M) systems, immunity/resistance to nisin, lacticin 481, cadmium and copper, and six conjugative/mobilization regions. A food-grade derivative strain with enhanced bacteriophage resistance was generated via stacking of R/M plasmids. Sequencing and functional analysis of the four plasmids of L. lactis subsp. lactis biovar. diacetylactis DPC3901 from raw milk cheese revealed genes novel to Lactococcus and typical of bacteria associated with plants, in addition to genes associated with plant-derived lactococcal strains. The functionality of a novel high-affinity regulated system for cobalt uptake was demonstrated. The bacteriophage resistant and bacteriocin-producing plasmid pMRC01 places a metabolic burden on lactococcal hosts resulting in lowered growth rates and increased cell permeability and autolysis. The magnitude of these effects is strain dependent but not related to bacteriocin production. Starters’ acidification capacity is not significantly affected. Transcriptomic analyses showed that pMRC01 abortive infection (Abi) system is probably subjected to a complex regulatory control by Rgg-like ORF51 and CopG-like ORF58 proteins. These regulators are suggested to modulate the activity of the putative Abi effectors ORF50 and ORF49 exhibiting topology and functional similarities to the Rex system aborting bacteriophage λ lytic growth.

Adsorption of sulfur dioxide on chemically modified natural clinoptilolite. Acid modification

Natural Bulgarian clinoptilolite from the south-eastern Rhodopes mountain was modified through treatment with hydrochloric acid with various normality, both single and repeatedly, as well as through a charring of a preliminary obtained NH4-form. The parameters concerning the uptake of the ion-exchangeable cations (Ca2+, Na+ and K+), as well as the uptake of aluminium from the natural material were calculated on the basis of the chemical contents. The highest extent of cations removal was attained in the case of the treatment with NH4Cl solution, while the highest aluminium deficiency was established in the samples treated by hydrochloric acid solutions with increasing concentration. Sulfur dioxide adsorption on the obtained decationised and dealuminised samples was studied according to the frontal-dynamic method. The parameters of the breakthrough curves, namely breakthrough time, saturation time and some of the statistical moments of the curve distribution, were determined. The dynamic adsorption capacities were also specified. Comparing the momentum values it was established that as a result of the natural zeolite treatment with NH4Cl and with low concentrated acid, the diffusion resistance decreases because of the dominant exchange of the presenting exchangeable cations in the samples with the smaller size protons and because of enlargement of the pores opening. Intensified dealuminisation was observed when more concentrated acid solutions are used. The capacity is enhanced, probably due to an increase in the total pore volume.

Costs of resistance: genetic correlations and potential trade-offs in an insect immune system

Theory predicts that natural selection will erode additive genetic variation in fitness-related traits. However, numerous studies have found considerable heritable variation in traits related to immune function, which should be closely linked to fitness. This could be due to trade-offs maintaining variation in these traits. We used the Egyptian cotton leafworm, Spodoptera littoralis, as a model system to examine the quantitative genetics of insect immune function. We estimated the heritabilities of several different measures of innate immunity and the genetic correlations between these immune traits and a number of life history traits. Our results provide the first evidence for a potential genetic trade-off within the insect immune system, with antibacterial activity (lysozyme-like) exhibiting a significant negative genetic correlation with haemocyte density, which itself is positively genetically correlated with both haemolymph phenoloxidase activity and cuticular melanization. We speculate on a potential trade-off between defence against parasites and predators, mediated by larval colour, and its role in maintaining genetic variation in traits under natural selection.

Protection of cattle against a natural infection of Fasciola hepatica by vaccination with recombinant cathepsin L1 (rFhCL1)

The liver fluke, Fasciola hepatica causes liver fluke disease, or fasciolosis, in ruminants such as cattle and sheep. An effective vaccine against the helminth parasite is essential to reduce our reliance on anthelmintics, particularly in light of frequent reports of resistance to some frontline drugs. In our study, Friesian cattle (13 per group) were vaccinated with recombinant F. hepatica cathepsin L1 protease (rFhCL1) formulated in mineral-oil based adjuvants, Montanide (TM) ISA 70VG and ISA 206VG. Following vaccination the animals were exposed to fluke-contaminated pastures for 13 weeks. At slaughter, there was a significant reduction in fluke burden of 48.2% in the cattle in both vaccinated groups, relative to the control non-vaccinated group, at p

Immunoselection of breast and ovarian cancer cells with trastuzumab and natural killer cells:selective escape of CD44high/CD24low/HER2low breast cancer stem cells

Although trastuzumab (Herceptin) has substantially improved the overall survival of patients with mammary carcinomas, even initially well-responding tumors often become resistant. Because natural killer (NK) cell-mediated antibody-dependent cell-mediated cytotoxicity (ADCC) is thought to contribute to the therapeutic effects of trastuzumab, we have established a cell culture system to select for ADCC-resistant SK-OV-3 ovarian cancer and MCF7 mammary carcinoma cells. Ovarian cancer cells down-regulated HER2 expression, resulting in a more resistant phenotype. MCF7 breast cancer cells, however, failed to develop resistance in vitro. Instead, treatment with trastuzumab and polyclonal NK cells resulted in the preferential survival of individual sphere-forming cells that displayed a CD44(high)CD24(low) "cancer stem cell-like" phenotype and expressed significantly less HER2 compared with non-stem cells. Likewise, the CD44(high)CD24(low) population was also found to be more immunoresistant in SK-BR3, MDA-MB231, and BT474 breast cancer cell lines. When immunoselected MCF7 cells were then re-expanded, they mostly lost the observed phenotype to regenerate a tumor cell culture that displayed the initial HER2 surface expression and ADCC-susceptibility, but was enriched in CD44(high)CD24(low) cancer stem cells. This translated into increased clonogenicity in vitro and tumorigenicity in vivo. Thus, we provide evidence that the induction of ADCC by trastuzumab and NK cells may spare the actual tumor-initiating cells, which could explain clinical relapse and progress. Moreover, our observation that the "relapsed" in vitro cultures show practically identical HER2 surface expression and susceptibility toward ADCC suggests that the administration of trastuzumab beyond relapse might be considered, especially when combined with an immune-stimulatory treatment that targets the escape variants.

Arsenate resistance in the ericoid mycorrhizal fungus Hymenoscyphus ericae

• Differential resistance to arsenate (AsO₄ ^3-) is demonstrated here among populations of the ericoid mycorrhizal fungus Hymenoscyphus ericae isolated from Calluna vulgaris in natural heathland soils and soils contaminated with AsO₄ ^3-. • Isolates (c. 25) of the fungus from each of two As and Cu mine sites, and a natural heathland site, were screened for AsO₄ ^3- and Cu²⁺ resistance by growing isolates in media containing a range of AsO₄ ^3- and Cu²⁺ concentrations. • H. ericae populations from the mine sites demonstrated resistance to AsO₄ ^3- compared with the heathland population; the mine-site populations producing significant growth at the highest AsO₄ ^3- concentration (4.67 mol m^-3), whereas growth of the heathland population was almost completely inhibited. EC₅₀ values for mine-site isolates were estimated to be 5-41-times higher than the heathland population. All isolates produced identical responses to increasing Cu²⁺ concentrations, with no differences observed between mine-site and heathland isolates. • Populations of H. ericae on the contaminated mine sites have developed adaptive resistance to AsO₄ ^3-. By contrast, Cu²⁺ resistance appears to be constitutive.

The vascular targeting agent combretastatin-A4 and a novel cis-Restricted {beta}-Lactam Analogue, CA-432, induce apoptosis in human chronic myeloid leukemia cells and ex vivo patient samples including those displaying multidrug resistance

Combretastatin-A4 (CA-4) is a natural derivative of the African willow tree Combretum caffrum. CA-4 is one of the most potent antimitotic components of natural origin, but it is, however, intrinsically unstable. A novel series of CA-4 analogs incorporating a 3,4-diaryl-2-azetidinone (β-lactam) ring were designed and synthesized with the objective to prevent cis -trans isomerization and improve the intrinsic stability without altering the biological activity of CA-4. Evaluation of selected β-lactam CA-4 analogs demonstrated potent antitubulin, antiproliferative, and antimitotic effects in human leukemia cells. A lead β-lactam analog, CA-432, displayed comparable antiproliferative activities with CA-4. CA-432 induced rapid apoptosis in HL-60 acute myeloid leukemia cells, which was accompanied by depolymerization of the microtubular network, poly(ADP-ribose) polymerase cleavage, caspase-3 activation, and Bcl-2 cleavage. A prolonged G(2)M cell cycle arrest accompanied by a sustained phosphorylation of mitotic spindle checkpoint protein, BubR1, and the antiapoptotic proteins Bcl-2 and Bcl-x(L) preceded apoptotic events in K562 chronic myeloid leukemia (CML) cells. Molecular docking studies in conjunction with comprehensive cell line data rule out CA-4 and β-lactam derivatives as P-glycoprotein substrates. Furthermore, both CA-4 and CA-432 induced significantly more apoptosis compared with imatinib mesylate in ex vivo samples from patients with CML, including those positive for the T315I mutation displaying resistance to imatinib mesylate and dasatinib. In summary, synthetic intrinsically stable analogs of CA-4 that display significant clinical potential as antileukemic agents have been designed and synthesized.