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Detailed studies have been made of the transformations and microstructure of the weld heat-affected zone (HAZ) of a class 212Cr–Mo steel, particular attention being given to δ-ferrite. The investigation covered a wide range of welding heat inputs and involved real and simulated HAZ material. To obtain the phasetransformation data extensive use was made of a weld simulator and dilatometer. The weld H AZ consisted of three regions: secondary-hardened martensite, homogeneous martensite, and duplex δ-ferrite and martensite adjacent to the fusion line. The amount of δ-ferrite increased with increasing weld heat input. It was shown that δ-ferrite forms above 1320°–1360°C, depending on the heat rate and remains untransformed on cooling to room temperature for the normal range of weld cooling rates. Detailed metallography showed that δ-ferrite forms at austenite grain boundaries, involves redistribution of allo ying elements and is associated with interphase precipitation of carbides. However, in amounts ...

Although cytomegalovirus (CMV) infections are common throughout the world, little is known about the means of person-to-person transmission. To determine whether infection could be established by a respiratory route, studies were conducted in a murine CMV (MCMV) model by using intranasal inoculation. The infectious dose which resulted in pulmonary and systemic infection of half the mice was 100 plaque-forming units of MCMV. Here, infection was subclinical, but virus replicated in the lungs and subsequently disseminated via the blood to other organs within 7 days. The serum immunofluorescence antibody titer peaked by day 21. None of these mice died, although focal peribronchial interstitial pneumonitis was found in infected animals. In mice given greater than or equal to 10(4) plaque-forming units of MCMV intranasally, severe diffuse interstitial pneumonitis resulted uniformly, closely resembling that seen in immunocompromised patients and in newborn infants, and 20% of the animals died. Normal pulmonary architecture was obliterated by sheets of histiocytes, many containing MCMV intranuclear inclusions, and by accumulation of proteinaceous fluid in the interstitial and alveolar spaces. Of relevance to human disease, these experiments show that MCMV as a sole pathogen can cause severe interstitial pneumonitis in normal mice and that subclinical systemic infection results from respiratory inoculation of small amounts of virus.

We report a 70-year-old man with the bullous variant of chickenpox. Physicians should be aware of this uncommon manifestation of this common disease, which may clinically suggest other bullous disorders such as pemphigus and bullous pemphigoid. A 24-year-old hospital worker developed typical chickenpox 2 weeks after the first patient's onset of bullous chickenpox.

A quantitative study has been made of the effects of welding and material variables on porosity formation in the tungsten inert gas arc welding of copper. It has been confirmed that porosity can result from the occurrence of the steam reaction in the weldpool. The extent of this porosity is increased by increasing water vapour content of the arc atmosphere, increasing oxygen content of the base material, and decreasing welding speed. All three factors interact so that the threshold porosity levelfor eachfactor is strongly influenced by the value of the other two factors. The steam reaction has been investigated during arc melting by determining the oxygen and hydrogen contents of copper buttons which have reacted with argon–water vapour atmospheres. It is shown that hydrogen ispreferentially absorbed from the arc following dissociation of the water vapour. The final levels of the oxygen and hydrogen in the button correspond to the equilibrium for the steam reaction in a high-temperature zone under...

An investigation has been made of the effect of composition and welding variables on liquation cracking in the weld heat-affected zone of low-alloy steels to specifications SAE 4130, En 24, and ASTMA 387B. It involved examination of bead-on-plate cracking tests made using the metal-inert-gas arc welding process. It was shown that cracking occurred in a discrete zone adjacent to the fusion boundary in which liquation of inclusions had taken place. The severity of cracking proved to be a function of both composition and welding variables. Under fixed welding conditions, cracking severity was related quantitatively to composition (in wt-%) by a linear regression equation of the form crack index=5·47C +27·27S+75·29P+2·79Si-2·77 In addition to confirming that increasing carbon and sulphur increased cracking, it was shown that phosphorus was a cracking promoter in its own right. For a steel of constant composition, cracking increased with (a) increased heat input/length, (b) increased depth offinger pen...

Three-dimensional reconstruction of serial sections, observed by microscopy, is an important technique in medicine and biology. To view any part of a structure clearly, that part has to be identified and clearly highlighted in its relationship to other features in a structure. The identification process can be time consuming and tedious if many sections are involved, especially for routine applications, since human identification is required. In this paper we describe how image processing, together with other information on the shape and position of features relative to each other on any one section and throughout the structure, could be incorporated into an expert system and we also show how such a system could be designed. An important feature is the use of human-computer interaction to allow the system to evolve under the guidance of the biological or medical expert. An example of feature identification in a plant-parasitic nematode is used.

The effects of the arachidonic acid metabolites prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) on the in vitro random migration of cloned murine T lymphocytes (derived from limiting dilution analysis of a C57BL/6 anti-DBA/2 mixed leukocyte culture) were examined. Experiments were also performed to study the effects of the cyclooxygenase inhibitor indomethacin on both random lymphocyte migration and lymphocyte migration in the presence of PGE2. The responses of cloned lymphocytes to PGE2 and LTB4 were compared with those of unsensitized lymph node lymphocytes. PGE2 at 100 ng/ml significantly inhibited (p less than 0.001) the in vitro migration of helper clones of T lymphocytes, but had no effect on random migration of cytotoxic T cells or helper independent cytotoxic (HIT) cloned cells. In contrast, LTB4 significantly (p less than 0.001) enhanced the random locomotion of helper, cytotoxic, and "HIT" cloned cells at 0.1 and 0.3 ng/ml. The effects of both PGE2 and LTB4 were found to be completely reversible by cell washing. Indomethacin (10(-7) M) did not alter random migration of any of the clones, and in particular, did not affect the inhibition of helper lymphocyte migration induced by PGE2. Unsensitized bulk lymph node lymphocyte migration was not affected by either PGE2 or LTB4. The results suggest that modulation of lymphocyte locomotor function by environmental stimuli may depend on cellular activation, and the locomotor responses of activated lymphocytes to arachidonic acid metabolites may be subset specific.

In basic biomedical research the details of many of the biological processes under study are not well understood; for example, the mechanism which allows macrophage cells to engulf and destroy foreign material. An imaging study of the effect of drugs on this process led to the development of a descriptive model, based on a computer graphics representation of the experimental biological images, to obtain a better understanding of the information obtained from the images. Deductive models have also been designed to investigate the underlying mechanisms of the process and to obtain maximum information from the existing data. The results of the model are presented as a graphic display in the same form as the descriptive model to allow for direct comparison between the model and the experimental data. This approach is generally useful in many areas of microscopy but it is illustrated here in a study of the action of macrophage cells.

The properties of a volume-phase hologram of the reflection type are studied in the case when the reference and object waves are beams of finite width. Numerical results are obtained by considering a sufficiently large number of terms in a previously derived infinite series solution. The results reproduce Kogelnik's one-dimensional theory [1] when the thickness of the hologram is small in comparison with the widths of the beams but otherwise the finiteness of the recording beams leads to significant variations in the amplitude of the reconstructed beam.

Viremia is a hallmark of disseminated cytomegalovirus (CMV) infection and disease. Using conventional virus culture and a subgenomic cloned CMV DNA probe to detect viral DNA within leukocytes, we studied the virus-cell interactions involved in immunocompromised patients with viremic CMV infection. CMV was recovered by culture in 17/17 samples enriched for polymorphonuclear leukocytes. Viral DNA was detected by dot-blot hybridization in 16/17 (94%). In contrast, samples enriched for mononuclear cells yielded infectious CMV in culture in only 7/15 (47%) instances; nonetheless, viral DNA was present in 16/17 samples probed. The quantity of CMV DNA in polymorphonuclear cells was significantly greater than in mononuclear leukocytes (mean 13.1 vs. 9.1 estimated viral genome equivalents per 100 cells, respectively), and CMV was always recovered from these cells regardless of the amount of viral DNA present. Yet, when the amounts of CMV DNA were virtually identical in granulocytes and mononuclear cells (6.3 and 7.1 genomic equivalents, respectively) collected simultaneously, infectious CMV could not be recovered from mononuclear cells. Although several interpretations are possible, these data are consistent with the view that CMV exists within granulocytes in a mature infectious form during viremia. The virus interactions with mononuclear cells appear to be more complex, particularly in those cells that contain CMV DNA but do not yield infectious virus.

Assembly of tubulin, purified from eggs of the sea urchin Stronglyocentrotus purpuratus, was examined at physiological (18 degrees C) and nonphysiological (37 degrees C) temperatures. Critical concentrations for assembly were 0.71 mg/ml at 18 degrees C and 0.21 mg/ml at 37 degrees C. At tubulin concentrations above 1.2 mg/ml at 18 degrees C and 0.5 mg/ml at 37 degrees C, a concentration-dependent "overshoot" in turbidity and in small-angle light scattering was observed; turbidity and scattering increased rapidly to a peak, then decreased asymptotically toward a steady-state value. Quantitative sedimentation analysis revealed that the mass of assembled polymer reached and maintained a constant level during overshoot of turbidity. Changes in the wavelength dependence of turbidity were consistent with the initial formation of sheets of tubulin, followed by conversion of the sheets to microtubules, both at 18 and 37 degrees C. Examination by negative-stain electron microscopy showed that sheetlike structures predominated during the early stages of overshoot assembly, while complete microtubules were present at steady state. Furthermore, measurements of average polymer length revealed that the overshoots in turbidity and in light scattering are unlikely to be caused by polymer length redistribution. Qualitative observations of solution birefringence suggested that the polymer became progressively more aligned during assembly. These results suggest that the turbidity/light-scattering overshoots reflect changes in the form or in the organization of the assembling polymer, or both.

Basic features of carbon black-aggregation of particles into structure, particle size and morphology, and surface activity-are reviewed. Carbon black reinforcement of vulcanizates is first examined in the example of tearing, and the influence of hysteresis is considered. The dynamic properties of vulcanizates containing two major types of reinforcing carbon black are compared. While particle size gives the best correlation with tensile strength of vulcanizates, surface activity is shown to be the key to reinforcement. The role of these properties of carbon black in dissipating rupture energy is discussed. The relation between work to tensile break and hysteresis to break in gum rubbers can be applied to black-reinforced vulcanizates by use of a strain amplification factor. The complication introduced by stress-softening is explained in terms of localized stress relaxation. Abrasion reinforcement can also be explained in terms of hysteresis. The Flory-Rehner relationship of modulus of elasticity o...

This paper discusses key factors in starting up local production of radials ahead of most other manufacturers, and how this affected comparative profitability. This led to the build-up of a viable capability for adapting basic overseas innovations to suit local conditions. It will be shown how this capability, in combination with independence in decision-making, compensated the Australian manufacturer relative to resources available to those manufacturers with overseas affiliations.

A simple container is described whereby small seedlings may be grown at controlled levels of water stress. The water stress was induced in the soil by an osmoticum which is separated from the soil by a semi-permeable membrane. The mortality ofBetula pendula seedlings was markedly increased at a matric potential of −1.6 bars whereas the mortality ofBuddleia davidii was only affected below −2.8 bars. This difference in tolerance to water stress at the seedling stage might not be reflected in the distribution of the species in the colonisation of chalk and sand pits in England unless there is a dry spring.

This study concerned the microstructure and fracture toughness of the weld heat-affected zone (HAZ) of the martensitic precipitation-hardened stainless steel FV520B. It included both air-melted and vacuum-remelted material and involved metal inert gas arc welding at a heat input of 1·78 kJ mm−1. While work was carried out on welded joints, most of the investigation made use of simulated HAZ material. Two preweld conditions were employed, namely primary hardened and overaged, and post-weld aging was carried out at 450°,550°, and 620°C. In all cases, the toughness was measured by the crack-opening displacement technique. The fracture toughness measured as crack-opening displacement at crack initiation δi in 6mm thick plate varied from 0·04 to 0·076mm for air-melted material and 0·069 to 0·081 mm for vacuum-remelted material. The actual value was influenced by heat-treatment condition and, in the case of air-melted plate, by orientation to the rolling direction. Areas of property variation were detec...

Reactivation of Toxoplasma gondii infection often occurs concurrently with active cytomegalovirus (CMV) disease in immunocompromised patients, and CMV disease results in immunosuppression. To determine if murine CMV (MCMV) infection decreases resistance to T. gondii, mice with latent T. gondii infection were infected with MCMV. T. gondii infection reactivated, manifested primarily as pneumonia. Lung macrophages supported the growth of T. gondii before, during, and after T. gondii reactivation. Peritoneal macrophages inhibited the growth of T. gondii as pneumonia developed and became permissive as pneumonia resolved. Mice with latent T. gondii infection could survive larger doses of MCMV than could controls. Thus, MCMV infection led to reactivation of latent T. gondii infection in mice. Activation of lung macrophages, assessed by their ability to inhibit replication of T. gondii in vitro, was not associated with control of T. gondii infection.

Callus was initiated from 15-day-old embryos of 'Carman' triticale (×Triticosecale Wittmack) cultured on 2,4-dichlorophenoxyacetic acid supplemented Murashige and Skoog (MS) medium. For plant regeneration, the calli were subcultured every 4 weeks on MS media with no added hormones. The original euploid (2n = 42) regenerated plants and their progeny were examined for several traits. Considerable variation for all measured traits was observed among the regenerated plants. Variability was greatest for spike length, fertility, and plant height. Two second-generation plants were found to have a significant increase in percent kernel protein relative to 'Carman' controls. Electrophoretic studies showed that all regenerated plants of both generations had the same prolamin banding pattern as 'Carman' triticale but variation existed in the intensity of the bands. This was especially true for the bands encoded for by the rye genome. One genotype, viz. R13, exhibited extreme chromosomal instability resulting in the occurrence of both rye and wheat univalents as observed at metaphase I.Key words: somaclonal variation, triticale, tissue culture, plant regeneration.

NK cell activity, defined by the ability of infiltrating host cells to lyse the YAC-1 tumor target, can be detected in sponge matrix allografts across all genetic barriers tested. Nonspecific tumor cell killing cannot be detected either within bulk populations of host-infiltrating cells or in populations enriched for non-adherent lymphocytes. NK activity is also detected in cells infiltrating a syngeneic sponge matrix graft although to a much lesser extent than an allogeneic graft. NK cell functional activity at the graft site precedes the appearance of alloimmune CTL by several days. The surface phenotype of the NK cell is Thy-1.2+ and L3T4- as determined by depleting the various subpopulations with antibody and C. Systemic treatment of sponge-bearing animals with repeated injections of anti-asialo GM1 (AGM1) results in inhibition of both NK activity and CTL activity recovered from the graft on days 5 to 9 after grafting, but on days 11 to 13 after grafting both NK activity and CTL activity are found within the sponge graft. Treatment of sponge-associated cells with anti-AGM1 in vitro or intrasponge injection of anti-AGM1 at various times after grafting eliminates NK activity more readily than alloimmune CTL activity. The intimate association observed between NK cells and alloimmune CTL at the graft site prompts further investigation into the role of NK cells in the allograft response.

Many cytomegalovirus (CMV) infections result from activation of virus previously latent in the host. Murine models of latent CMV infection have been developed in which latent virus can be activated in vivo by immunosuppression or by coculture of splenic lymphocytes in vitro. In the present study, latent murine CMV (MCMV) could be activated from lymphocytes of mice regardless of genetic strain, age at time of virus inoculation, or use of syngeneic or allogeneic fibroblasts for coculture. After intraperitoneal inoculation, virulent virus was activated from lymphocytes more often than attenuated MCMV (69%o vs. 20%7 of lymphocyte cocultures were positive, respectively). Latent MCMV was not detected in lymphocytes after subcutaneous inoculation of weanling mice but could be activated from mice infected subcutaneously as newborns. The absence of latent infection in the lymphocytes of the mice that had been inoculated as weanlings was due to lack of virus replication in the spleen during acute infection.

In this paper, the authors examine the correlation between hot-ductility test data obtained in simulated weld thermal cycles and weld heat-affected zone (HAZ) liquation cracking in ferritic, low-alloy steels of the En 24, SAE 4130, and ASTM A387B types. The work covered steels containing various levels of carbon, sulphur, and phosphorus whose cracking susceptibility had already been quantitatively assessed. It was shown -that hot-ductility testing under the conditions of thermal simulation reproduced the metallurgical processes occurring in the real weld HAZ and was, therefore, a valid method of investigation. Furthermore, it was demonstrated that the severity of cracking in these steels could be related quantitatively to the zero ductility range (ZDR) measured during cooling, provided that the peak temperature was equivalent to or higher than the nil strength temperature. Since the ZDR and weld-cracking susceptibility were affected in a similar way by the elements carbon, sulphur, and phosphorus,...

An immunocompromised woman died of disseminated infection due to adenovirus type 3. During her hospitalization and after her death, 38 hospital personnel developed an acute respiratory illness. Adenovirus type 3 infection was documented by culture in 18 of the 38 individuals and by seroconversion in one additional employee. Four of 34 asymptomatic hospital personnel exposed to the index case also seroconverted. Thus, 23 personnel were considered to have confirmed infections, and 22 of these 23 reported direct contact with the index case. Acquisition of infection was associated with the number and type of contacts. Protection against infection was associated with detectable serum-neutralizing antibody in the early serological sample. Restriction enzyme analysis using six different endonucleases indicated that all isolates of virus were type 3a and had identical genetic composition. This study underscores the importance of adenovirus as a cause of nosocomial infection and indicates that genetic analysis of viral DNA is a powerful tool for studying common-source outbreaks.

Summary Trans fatty acids are formed during the catalytic hydrogenation of animal and vegetable oils and occur naturally in dairy and ruminant tissue fats. Numerous studies have been made of the physiological effects of these acids.1 Recently, the COMA report on “Diet and Cardiovascular Disease”2 recommended the inclusion of a combined trans and saturated fatty acid contents in labelling of fatty foods. The analysis of trans fatty acids in widely differing food fats is by no means straightforward and the choice of analytical method needs careful consideration. Techniques including infrared spectroscopy, gas chromatography and argentation chromatography are described in this review. The infrared technique is the most suitable for labelling purposes, being rapid, simple, reproducible and applicable to all food fats including those containing hydrogenated fish oils. It is suggested that the IUPA C Official Method3 should be specified in any labelling regulations to ensure the reliability of the data and to facilitate comparison of figures produced by different laboratories.

Summary Oedema of the umbilical cord, defined as visible oedema in a cord wish a minimal cross sectional area of 1.3 cm2, is found in 10 per cent of deliverieo. It is seen more frequently in certain complications of pregnancy such as abrupti placentage, maternal diabetes, macerated intrauterine death and in conditions affectint the infant including prematurity, rhesus isoimmunization, respiratory distress syndrome (RDS) and transient respiratory distress (TRD). There is a higher incidence in infants delivered by Caesarean section. There is no significant association between cord oedema and either fetal distress or neonatal asphyxia nor is there any correlation with maternal hypertension or oedema. The mechanism of production of the oedema is discussed; low oncotic pressure, raised hydrostatic pressure in the placenta and umbilical cord, and an increase in total water in the feto-placental unit are considered. The presence of oedema of the cord may reflect similar changes in the lungs which antenatally predispose an infant whose pathway for production of surfactant is immature to develop RDS and the mature infant to develop TRD. The value of cord oedema as a warning sign is stressed.

Internal friction measurements have been made on electron-irradiated gold. The change in friction as a function of the total integrated electron flux was measured at 80°K and 280°K for an electron energy of 2 Mev. It was found that the results can be explained in terms of dislocation pinning if there are at least two dislocation systems present. After irradiation near 15°K, little or no direct pinning was observed, but on annealing continuous pinning was observed between 25°–75°K. Pinning also occurred in the temperature ranges 170°–220°K, 240°–260°K and 280°–320°K on warming up after irradiations at 80°K. These pinning stages were superimposed on a background of depinning. The ratio of the number of defects reaching the dislocations during the first two pinning stages was found to depend on the electron energy. The results are compared with those found in copper and the similarity suggests that the nature of the irradiation damage is the same in both metals.

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(1947). John Smyth and Thomas Helwys: The Two First English Preachers of Religious Liberty. Resemblances and Contrasts. Baptist Quarterly: Vol. 12, No. 6-7, pp. 187-195.

Carbenicillin is a new penicillin with a broad spectrum of action against many gram-negative pathogens [1]. Attention has been focused primarily on its activity against Pseudomonas aeruginosa, since agents currently available for the treatment of infections due to this organism are potentially toxic. This report describes results of treatment with carbenicillin in 25 patients, most of whom had severe infections due to Pseudomonas.

Summary A previously described fluorescent antibody procedure that makes use of antibody absorption was used for the study of the sera of human volunteers in the strain E typhus vaccination experiments. These individuals had been vaccinated with either living strain E epidemic typhus rickettsiae or commercial killed epidemic typhus vaccine. They and several unvaccinated controls were subsequently challenged with living virulent rickettsiae of either epidemic typhus or murine typhus. In response to infection the unvaccinated controls formed specific (noncross-reacting) antibody that was directed toward the infecting rickettsiae. Similar results were seen in those (epidemic) vaccinated individuals who were infected with epidemic rickettsiae. Contrasting results were seen in the eight persons who received (epidemic) vaccine and were then infected with murine typhus rickettsiae. Five of these formed during their infection specific antibodies directed toward epidemic rickettsiae, two had mixed responses, and only one formed specific antibody for the infecting (murine) rickettsiae. These results indicate that the specificity of the antibody response is usually not a reliable indicator of the infecting type of typhus rickettsiae in persons who have had earlier immunologic experience with typhus antigen. In the United States this would include vaccinated members of the armed forces, and former inhabitants of eastern Europe. The latter group contains the individuals in whom recrudescent epidemic typhus, or Brill's disease, might be suspected.

It is assumed that the first step in the hydrohalogenation of a diene under conditions such that an ionic mechanism is operative involves the formation of a linear carbonium ion via attachment of a proton to the 1-position and that the second step involves addition of the halide ion to either the 2- or 4-positions. If it is also assumed that hyperconjugation plays some non-negligible role in the carbonium ion intermediate, then it turns out that the use of Huckel theory charge densities and localization energies predict (1) that the 1,2-product is kinetically favored in the cases of butadiene and isoprene, (2) that the 1,4-product is kinetically favored in the case of chloroprene, and (3) that the 1,4-product is thermodynamically favored in all of the above systems. All of these predictions appear to be in agreement with available experimental results.

A study has been made of the effects of material composition on weld metal soldification cracking in the autogenous tungsten-inert gas arc welding of thin low-alloy steel sheet. Published data obtained for about eighty steels have been examined by regression analysis to produce a linear relationship between cracking susceptibility and composition which is both simpler and superior to earlier complex expressions. Using the Huxley cracking test new data were obtained for a range of steels to specifications En 24, SAE 4130 and ASTM A387B as well as several aircraft compositions. The results confirmed the crack-promoting influences of sulphur, phosphorus, and carbon already identified in the cracking relationship, and also revealed a major crack-inhibiting effect of oxygen. These findings were used to produce the following expression linking cracking and composition for these steels under the standardized conditions of the Huxley weld cracking test, i.e. the crack susceptibility factor (CSF) =42 (wt-%...

The concept of saturation island density (i.e. numbers of discrete groups of atoms) is critically examined. Equations for nucleation and growth are derived, taking into account the random nature of evaporation and the competition of the processes consuming atoms, and it is shown that saturation never occurs. The concept of fractional nucleation rate is introduced; this is defined as the quotient of the nucleation rate and the island density. This parameter can be used experimentally to find values of the energy parameters which govern the nucleation and growth processes.

The fracture toughness and microstructure of the heat-affected zone of welded 300 grade maraging steel have been studied. A wide range of welding processes has been covered using a thermal simulation technique. This approach has been justified by correlating real and simulated heat-affected zone properties and structures. Fracture toughness has been found to be a function of peak temperature, but independent of heating and cooling rates. Increases in fracture toughness were found and related to peak temperature, specific values being 75 MNm−3/2; (67·8 ksi√in) at 650°C and 66–;77·5 MNm−3/2 (59·6–70·1 ksi√in) over 12000–1400°C, as compared with the parent material value of 60 MNm−3/2 (54·2 ksi√in). These increases inf racture toughness were accompanied by decreases in tensile strength in all cases. The metallographic, fractographic and fracture toughness results have been correlated to explain the observed changes in properties. It is shown that reverted austenite gives increased toughness at 650°C ...