In vitro growth of mastitis pathogens in mammary secretions of the dry and peripartum periods

In vitro growth of Escherichia coli, Streptococcus uberis, and Staphylococcus aureus was measured in skimmed, cell-free secretions of bovine mammary glands collected on d 0, 7, 14, and 28 of the dry period; 12, 8, and 4 d before expected calving; and on d 0 and 14 postpartum. There were marked and nearly inverse changes in growth of Escherichia coli and Streptococcus uberis over the experimental period. Escherichia coli grew well in secretions of d 0 of the dry period and d 0 and 14 postcalving but poorly or not at all in secretions of the mid-dry period. In contrast, Streptococcus uberis grew well in secretions of the involuted gland and poorly in samples from day of dry off and day of calving. Growth of Staphylococcus aureus changed relatively little over the dry period, but there was reduction in growth at d 7 of the dry period. Changing ability of the secretion to support bacterial growth may influence changing susceptibility to infection, but for Streptococcus uberis, poor correspondence between changes in growth supported by the secretion and changes in the incidence of naturally occurring infection over the dry period indicates that other factors may be more important.     

An evaluation of fiber-reinforced titanium matrix composites for advanced high-temperature aerospace applications

The current capabilities of continuous silicon-carbide fiber-reinforced titanium matrix composites (TMCs) are reviewed with respect to application needs and compared to the capabilities of conventional high-temperature monolithic alloys and aluminides. In particular, the properties of a firstgeneration titanium aluminide composite, SCS-6/Ti-24Al-11Nb, and a second-generation metastable beta alloy composite, SCS-6/TIMETAL 21S, are compared with the nickel-base superalloy IN100, the high-temperature titanium alloy Ti-1100, and a relatively new titanium aluminide alloy. Emphasis is given to life-limiting cyclic and monotonie properties and to the influence of time-dependent deformation and environmental effects on these properties. The composite materials offer a wide range of performance capabilities, depending on laminate architecture. In many instances, unidirectional composites exhibit outstanding properties, although the same materials loaded transverse to the fiber direction typically exhibit very poor properties, primarily due to the weak fiber/matrix interface. Depending on the specific mechanical property under consideration, composite cross-ply laminates often show no improvement over the capability of conventional monolithic materials. Thus, it is essential that these composite materials be tailored to achieve a balance of properties suitable to the specific application needs if these materials are to be attractive candidates to replace more conventional materials. This article is based on a presentation made in the symposium entitled “Creep and Fatigue in Metal Matrix Composites” at the 1994 TMS/ASM Spring meeting, held February 28–March 3, 1994, in San Francisco, California, under the auspices of the Joint TMS-SMD/ASM-MSD Composite Materials Committee.     

Effects of natural intramammary Corynebacterium bovis infection on milk yield and composition

The objective was to assess effect of Corynebacterium bovis infection of the bovine mammary gland on milk yield and composition. Yield and composition of milk from 53 Corynebacterium bovis-infected quarters of 44 cows at four consecutive milkings were compared with those of the contralateral uninfected quarters. Differences between infected and uninfected quarters in milk, fat, and protein yield and in fat and protein content were small and statistically nonsignificant. Numbers of somatic cells were moderately but significantly higher (119,000 vs. 79,000 cells/ml) in infected than in uninfected quarters.     

Construction materials development in sulfur–iodine thermochemical water-splitting process for hydrogen production

The sulfur iodine (SI) water splitting cycle for hydrogen production consists of three coupled chemical reactions, which includes the generation and decomposition of HI. The _HIx${\mathrm{HI}}_x$ environment is extremely corrosive and the severity increases with temperature. Immersion coupon corrosion screening tests were performed on materials selected from four classes of corrosion resistant materials: refractory metal, reactive metal, superalloys and ceramics. Of the materials tested, only Ta and Nb-based refractory metals and ceramic mullite can tolerate the extreme _HIx${\mathrm{HI}}_x$ environment. Severe pitting and dissolution was observed in two different reactive metal zirconium. A nickel based superalloy, C-276, also showed severe dissolution in _HIx${\mathrm{HI}}_x$ solution. The materials which showed good corrosion behavior will undergo further long-term immersion testing to assess performance. In addition, C-ring, U-bend and DCB test samples fabricated from qualified materials will be tested under stress corrosion conditions to investigate their crack initiation and growth properties.     

N.J. court committee requires most out-of-state lawyers to register for ADR

A New Jersey Supreme Court committee issues an unauthorized practice of law opinion that calls into question who can represent a party in private ADR matters. Based on recent-vintage changes to attorneys' model conduct rules, the move, while extreme, also may be part of a larger trend nationwide