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Laser absorptance (coupling efficiency) changes rapidly during laser metal processing due to temperature and multiple phase changes. We find that there is limited literature data available, but that this property is vital for accurate process simulations, as well as the fundamental understanding of the dynamics of high-power laser-matter interaction. We measure the dynamic, absolute absorbed power with sub-microsecond resolution during a 10 ms laser spot weld in 316L stainless steel from conduction to keyhole welding conditions using an integrating sphere. Our data show several important features including the points of melting and keyhole formation. Conclusions from the optical data are supported by weld cross-section analysis.

A novel pyroelectric detector consisting of a vertically aligned nanotube array on thin silicon (VANTA/Si) bonded to a 60 μm thick crystal of LiTaO_3 has been fabricated. The performance of the VANTA/Si-coated pyroelectric detector was evaluated using National Physical Laboratory’s (NPL’s) detector-characterization facilities. The relative spectral responsivity of the detector was found to be spectrally flat in the 0.8–24 μm wavelength range, in agreement with directional-hemispherical reflectance measurements of witness samples of the VANTA. The spatial uniformity of response of the test detector exhibited good uniformity, although the nonuniformity increased with increasing modulation frequency. The nonuniformity may be assigned either to the dimensions of the VANTA or the continuity of the bond between the VANTA/Si coating and the pyroelectric crystal substrate. The test detector exhibited a small superlinear response, which is similar to that of pyroelectric detectors coated with good quality gold-black coatings.

We study the laser irradiance behavior and resulting structural evolution of polymer-derived silicon–boron–carbonitride (Si(B)CN) functionalized multiwall carbon nanotube (MWCNT) composite spray coatings on copper substrate. We report a damage threshold value of 15 kWcm-2and an optical absorbance of 0.97 after irradiation. This is an order of magnitude improvement over MWCNT (1.4 kWcm-2, 0.76), SWCNT (0.8 kWcm–2, 0.65) and carbon paint (0.1 kWcm–2, 0.87) coatings previously tested at 10.6 μm (2.5 kW CO2laser) exposure. Electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy suggests partial oxidation of Si(B)CN forming a stable protective SiO2phase upon irradiation.

We have developed a pump-probe configuration to measure the carrier lifetime using the transient free-carrier density. The free-carrier absorption varies as λ2 Δn/μ, where λ is 10.6 μm in this paper. We measure the transient photoconductive decay that is proportional to Δn * μ. The data product gives Δα * Δσ~ λ2 Δn(t)2. The mobility variation is nullified by multiplying the data from the two parallel measurements. From the product data, both Δn(t) and μ(Δn) can be determined. A large increase in Δα and decrease in μ are observed and caused by space-charge effects in regions of high injection. These data show the unexpected and remarkable result that the lifetime is relatively constant up to an injection level of about three times the doping level. However, the mobility decreases by about a factor of six over the same injection range.

We demonstrate synthesis of a polymer-derived ceramic (PDC)-multiwall carbon nanotube (MWCNT) composite using microwave irradiation at 2.45 GHz. The process takes about 10 min of microwave irradiation for the polymer-to-ceramic conversion. The successful conversion of polymer coated carbon nanotubes to ceramic composite is chemically ascertained by Fourier transform-infrared and X-ray photoelectron spectroscopy and physically by thermogravimetric analysis and transmission electron microscopy characterization. Frequency dependent dielectric measurements in the S-Band (300 MHz to 3 GHz) were studied to quantify the extent of microwave–CNT interaction and the degree of selective heating available at the MWCNT-polymer interface. Experimentally obtained return loss of the incident microwaves in the specimen explains the reason for heat generation. The temperature-dependent permittivity of polar molecules further strengthens the argument of internal heat generation.

The performance of a 10 mm diameter pyroelectric detector coated with a single-wall carbon nanotube (SWCNT) was evaluated in the 0.8 to 20 ?m wavelength range. The relative spectral responsivity of this detector exhibits significant fluctuations over the wavelength range examined. This is consistent with independent absorbance measurements, which show that SWCNTs exhibit selective absorption bands in the visible and near-infrared. The performance of the detector in terms of noise equivalent power and detectivity in wavelength regions of high coating absorptivity was comparable with gold-black-coated pyroelectric detectors based on 50 ?m thick LiTaO_3 crystals. The response of this detector was shown to be nonlinear for DC equivalent photocurrents >10^?9 A, and its spatial uniformity of response was comparable with other pyroelectric detectors utilizing gold-black coatings. The nonuniform spectral responsivity exhibited by the SWCNT-coated detector is expected to severely restrict the use of SWCNTs as black coatings for thermal detectors. However, the deposition of SWCNT coatings on a pyroelectric crystal followed by the study of the prominence of the spectral features in the relative spectral responsivity of the resultant pyroelectric detectors is shown to provide an effective method for quantifying the impurity content in SWCNT samples.

We describe the results of a comparison of reference standards between three National Metrology Institutes: the National Institute of Standards and Technology (NIST, USA), the National Metrology Institute of Japan/National Institute of Advanced Industrial Science and Technology (NMIJ/AIST, Japan), and the Federal Office of Metrology (METAS, Switzerland). Open-beam- (free field) and optical-fiber-based measurements at wavelengths of 1302 and 1546 nm are reported. Three laboratories' reference standards are compared by means of two temperature-controlled, optical trap detectors. Measurement results show the largest differences of less than 4.2 parts in 10^3, which is within the expanded (k=2) uncertainty for the laboratories' reference standards.

The performance of a pyroelectric detector with a carbon multiwalled nanotube coating was evaluated in the 0.9-14 µm wavelength range. The relative spectral responsivity of this detector was shown to be flat over most of the wavelength range examined, and the spectral flatness was shown to be comparable to the best infrared black coatings currently available. This finding is promising because black coatings with spectrally flat absorbance profiles are usually associated with the highest absorbance values. The performance of the detector (in terms of noise equivalent power and specific detectivity) was limited by the very thick (250 µm thick) LiNbO_3 pyroelectric crystal onto which the coating was deposited. The responsivity of this detector was shown to be linear in the 0.06-2.8 mW radiant power range, and its spatial uniformity was comparable to that of other pyroelectric detectors that use different types of black coating. The carbon nanotube coatings were reported to be much more durable than other infrared black coatings, such as metal blacks, that are commonly used to coat thermal detectors in the infrared. This, in combination with their excellent spectral flatness, suggests that carbon nanotube coatings appear extremely promising for thermal detection applications in the infrared.

Cytochrome P-450, NADPH-cytochrome P-450 reductase, and glucuronyltransferase were immobilized simultaneously on cyanogen bromide-activated Sepharose from phenobarbital-induced rabbit liver microsomes. The activity of the P-450 system was demonstrated by the N-demethylation of ethylmorphine and the O-demethylation of p-nitroanisole. p-Nitrophenol produced from the oxidation of p-nitroanisole was conjugated to p-nitrophenyl glucuronide, as evidenced by isolation and characterization of the glucuronide by GC/MS.

The difference in DNA content of peripheral lymphocytes from normal males, normal females, and an individual with a 48 (xxxy) chromosome constitution was determined by rapid flow microfluorometric techniques. A similar comparison was performed using tissue culture fibroblasts derived from an individual with a 49 (xxxxy) chromosome constitution and WI-38 cells as a normal control. Less than 60 min were required to isolate the lymphocytes, to stain the cells fluorescently, and to measure the increased DNA content. The measured increase in DNA content is consistent with chromosome DNA analyses and chromosome length measurements.

Simian virus 40 (SV40) infection stimulates confluent cultures of monkey kidney cells into successive rounds of cellular DNA synthesis without intervening mitosis. As an initial step in defining the mechanisms responsible for viral inhibition of mitosis, M-phase-promoting factor (MPF) was examined in SV40-infected CV-1 cells passing from G2 phase into a second S phase. MPF is a serine-threonine protein kinase that is essential for mitosis in eukaryotic cells. In SV40-infected cells exiting G2 phase, there was a reduced amount of MPF-associated H1 kinase activity relative to that of uninfected cells passing through mitosis. Both subunits of MPF, cyclin B and the p34cdc2 catalytic subunit, were present and in a complex in infected cells. In uninfected cultures, passage through mitosis was associated with the dephosphorylation of the p34cdc2 subunit, which is characteristic of MPF activation. In contrast, the p34cdc2 subunit remained in the tyrosine-phosphorylated, inactive form in SV40-infected cells passing from G2 phase into a second S phase. These results suggest that although the MPF complex is assembled and modified normally, SV40 interferes with pathways leading to MPF activation.

Murine embryonal carcinoma F9 cells, a tissue culture model for early embryonic development, do not produce interferon (IFN) in response to poly(I-C), as determined by an antiviral assay. RNase protection analyses were used to examine total RNA extracted from the cells for the presence of beta-IFN RNA. Whereas F9 cells differentiated in vitro with retinoic acid produced a biologically active protein as well as beta-IFN RNA in response to poly(I-C), undifferentiated F9 cells produced no detectable beta-IFN RNA even in the presence of cycloheximide, an IFN-superinducing agent. These results show that undifferentiated embryonal carcinoma cells do not accumulate beta-IFN RNA in response to an IFN-inducing agent, suggesting a transcriptional regulatory mechanism. However, this control mechanism is altered upon differentiation, since the gene can be transcriptionally activated in retinoic acid-differentiated cells.

Infection of quiescent CV-1 cells with simian virus 40 mutant tsA30 at 37 degrees C resulted in the induction of two rounds of cellular DNA synthesis in T-antigen-positive cells, as previously described for wild-type simian virus 40. Following infection with tsA30 at 40.5 degrees C, T-antigen-positive cells were induced into S phase and reached a diploid G2 DNA content; however, a second S phase was not initiated. The failure of tsA30-infected CV-1 cells to enter tetraploid S phase at 40.5 degrees C identifies a T-antigen function, distinct from T-antigen functions responsible for stimulation of cell DNA synthesis, which is required for initiation of a second round of DNA synthesis without mitosis.

T antigen was localized in simian virus 40 lytically infected and transformed cells by Fab' antibody conjugates at the ultrastructural level. This virus-specific protein appeared in the cytoplasm of permissive cells as early as 3 h after infection. At later time intervals, the T antigen was localized in both the cytoplasm and nucleus and finally (24 h) in the nucleus. These results suggest a synthesis of T antigen on cytoplasmic ribosomes, with subsequent transfer to the nucleus.

Replication of two Chinese hamster embryo cell lines transformed by an early temperature-sensitive mutant of simian virus 40, tsA58, was examined by flow microfluorometry and autoradiography of [3H]thymidine-labeled cells in order to determine whether transformed cell DNA synthesis is initiated by the virus A gene. At the permissive temperature (37 degrees), cells transformed by the mutant were like the wild-type virus transformants in appearance, colony-forming ability, high saturation density, and rapid replication. At the nonpermissive temperature (40.5 degrees), the tsA58 transformed cells resembled normal embryo fibroblasts and seem to return to normal growth patterns. Although both mutant transformed cell lines at 40.5 degrees appeared to cease growth at low saturation density, the cells did not enter a resting state, but continued to replicate. The cultures were maintained at low densities by a balance among cell replication, cell death, and sloughing of dead cells into the supernatant. These results suggest that the simian virus 40 A gene function effected by the tsA58 mutation does not prevent Chinese hamster embryo transformed cells from entering a resting state, although the gene may control other phenotypic characteristics of transformation.

A case of a child with allergic asthma and mucocele of the paransal sinus who developed orbital hypertelorism is presented. The association between allergy and asthma and the formation of mucoceles is discussed and a possible mechanism for the development of orbital hypertelorism during adolescence is suggested. The management of mucoceles of the paranasal sinuses during craniofacial surgery is described. The need for long-term follow-up is emphasized.

In 1984, a press release by a Miami, Florida, neurologist described a possible cluster of persons with multiple sclerosis in Key West, Florida. The authors examined the cluster using prevalence rates, which are recognized as having a latitudinal gradient for multiple sclerosis, being generally high at high latitudes and low at low latitudes. Case ascertainment showed 32 definite or probable cases among residents of the study area (latitude, 24.5 degrees N) on September 1, 1985, a prevalence rate of 70.1/100,000 population--14 times the rate estimated for this latitude by modeling techniques based on US and international data, 7-44 times the rate for areas at similar latitudes (Mexico City, Mexico; Hawaii; New Orleans, Louisiana; and Charles County, South Carolina), and 2.5 times the expected rate for all US latitudes below 37 degrees N. This finding could not be explained by changes in diagnostic criteria, case ascertainment bias, immigration of people from high-risk areas, an unusual population structure, a large percentage of related cases, or better survival. Prevalent cases (n = 22) were more likely than general population controls (n = 76), matched by sex and 10-year age group, to have: lived longer in Key West, been a nurse, ever owned a Siamese cat, had detectable antibody titers to coxsackievirus A2 and poliovirus 2, and ever visited a local military base (Fleming Key). Key West has an unusually high prevalence of multiple sclerosis that may be related to these risk factors.

A flow cytometric assay has been developed to detect and quantitate human immunodeficiency virus (HIV)-infected peripheral blood mononuclear cells obtained from HIV-seropositive patients. Peripheral blood was obtained from patients attending an acquired immune deficiency syndrome clinic, and mononuclear cells were separated by centrifugation onto Ficoll-Hypaque. The cell layer at the interface was removed, washed in phosphate-buffered saline without Ca2+ and Mg2+, and fixed with 90% methanol, and intracellular HIV antigens were detected by indirect immunofluorescence with monoclonal antibodies to HIV antigens as the primary antibody and fluorescein isothiocyanate-conjugated goat anti-mouse immunoglobulin G F(ab')2 antibody as the secondary antibody. DNA content was determined by propidium diiodide staining after RNase treatment. These fluorochrome-treated cells were analyzed for two-color fluorescence by flow cytometry. The results showed that HIV-infected cells in peripheral blood that have been treated with monoclonal antibodies to the p24 or nef antigens of HIV can be detected and quantitated by flow cytometry. The percentage of p24 antigen-positive mononuclear cells had a significant correlation (P = 0.0001) with the clinical status of the patient, i.e., those with a high percentage of p24 antigen-positive cells had a poorer prognosis than those with a lower percentage of p24 antigen-positive mononuclear cells. In addition, for those in Centers for Disease Control groups III and IV, there was an inverse correlation between the percentage of p24 antigen-positive mononuclear cells and the number of T4 cells. However, cell-associated antigen detection by flow cytometry did not correlate with detection of antigen in sera of HIV-seropositive patients by the standard antigen capture enzyme-linked immunosorbent assay. This lack of correlation was probably due to the presence of immune complexes in the sera of HIV-seropositive patients. These results suggest that flow cytometry can be used as a rapid, sensitive, and quantitative assay system for the determination of the antigen status of HIV-seropositive patients and that it may be more useful as an indicator of disease progression than the currently used antigen detection methods.

The infection of secondary cultures of Chinese hamster cells with simian virus 40 (SV40) induces the appearance of cells with polyploid deoxyribonucleic acid (DNA) content or chromosomal component within one cell generation. The mechanism of this phenomenon was studied by the use of 5-bromodeoxyuridine (BUdR) incorporation as a DNA density marker. When cultures were treated with 14C-BUdR and colcemide and harvested at 48 hr postinfection, only hybrid and light DNA molecules were found in control cultures, whereas in infected cultures there were also heavy molecules. The proportion of heavy DNA synthesized during the experimental period varied from 13 to 25%. It was determined by DNA-DNA hybridization that the heavy DNA consisted of cellular DNA. In radioautographic experiments, it was shown that, under the conditions used, a fraction of the infected cell population twice replicated its complete DNA content. Analysis of the kinetics indicated that the heavy DNA resulted from the reinitiation of DNA synthesis after the initial replication of the entire cell DNA. It was concluded that, after infection with SV40, a fraction of the Chinese hamster cell population undergoes two cycles of DNA synthesis without intervening mitosis.

Simian virus 40 deoxyribonucleic acid (DNA) became associated in an alkaline-stable form with the DNA of Chinese hamster embryo cells at 15 to 20 hr post-infection, at the time when cell DNA synthesis and T antigen were induced. The integration process was not inhibited by d-arabinosyl cytosine and was only partially inhibited by cycloheximide.

The main recent discoveries about vertebrates in North Africa, Sahara, and Israel Trias are reviewed. It is shown that the Middle Trias fauna in the South of Tunisia and that of Israel show true affinities, and that they are both of a marine origin. Conversely, vertebrate faunas in Morocco Trias are continental ones and contain a number of fossils which are found also in Central Sahara Trias (Edjelé).Sahara and South Morocco must have been, for the most part, emerged lands during the Triassic time and had probably some estuaries where marine incursions could penetrate, or were occasionally covered by shallow and temporary seas.

Kováts retention indices can be used to characterize the gas chromatographic behavior of C1 and C2 halocarbons on Porapak Q. Within each series of halocarbons the retention index increases with chlorine content, decreases with fluorine and hydrogen content, and is directly proportional to molecular weight and boiling point. Substitution of a fluorine or a bromine atom for a chlorine atom in these compounds results in characteristic changes in the retention index. The heats of adsorption are in the neighborhood of the latent heats of vaporization for the compounds examined.

The aim in all bronchography for the diagnosis of bronchopulmonary suppurative disease is complete five-lobe bronchial mapping. Accurate localization of the extent of bronchial disease is essential for proper surgical extirpation of the affected bronchopulmonary segments. It is deplorable that good bronchography is the exception rather than the rule.

A carbon nanotube cryogenic radiometer (CNCR) has been fabricated for electrical-substitution optical power measurements. The CNCR employs vertically aligned multiwall carbon nanotube arrays (VANTAs) as the absorber, heater, and thermistor, with a micromachined silicon substrate as the weak thermal link. Compared to conventional cryogenic radiometers, the CNCR is simpler, more easily reproduced and disseminated, orders of magnitude faster, and can operate over a wide range of wavelengths without the need for a receiver cavity. We describe initial characterization results of the radiometer at 3.9 K, comparing electrical measurements and fiber-coupled optical measurements from 50 μW to 1.5 mW at the wavelength of 1550 nm. We find the response to input electrical and optical power is equivalent to within our measurement uncertainty, which is currently limited by the experimental setup (large temperature fluctuations of the cold stage) rather than the device itself. With improvements in the temperature stability, the performance of the CNCR should be limited only by our ability to measure the reflectance of the optical absorber VANTA.

A picowatt cryogenic radiometer (PCR) has been fabricated at the microscale level for electrical substitution optical fiber power measurements. The absorber, electrical heater, and thermometer are all on a micromachined membrane less than 1 mm on a side. Initial measurements with input powers from 50 fW to 20 nW show a response inequivalence between electrical and optical power of 8%. A comparison of the response to electrical and optical input powers between 15 pW to 70 pW yields a repeatability better than ±0.3% (k=2). From our first optical tests, the system has a noise equivalent power of ≈5×10^−15??W/Hz at 2 Hz, but simple changes to the measurement scheme should yield an NEP 2 orders of magnitude lower.

Porcine reproductive and respiratory virus (PRRSV) significantly reduces pig performance. The AA requirements and Lys:ME of health challenged pigs for optimum performance are poorly understood. Two experiments were conducted to evaluate the effect of increasing SID Lys:ME (g Lys per Mcal ME) on growth performance during a PRRSV challenge. In Exp. 1, 379 barrows (51.3 ± 0.3 kg BW) were allotted to one of six diets (1.87-3.41 Lys:ME) for a 35-d growth study. In Exp. 2, 389 barrows (29.2 ± 0.23 kg BW) were allotted to one of six diets (2.39-3.91 Lys:ME) for a 49-d growth study. These isocaloric diets represented 80, 90, 100, 110, 120 and 130% of NRC SID Lys requirement. For each Exp., pigs were randomly allocated to two barns of 24 pens each with 7-9 pigs/pen (4 pens/diet/health status). On day 0, one barn was inoculated with live PRRSV, one barn sham inoculated (control), and all pigs were started on experimental diets. Pen growth performance and feed intake were recorded weekly and G:F calculated. Breakpoint analysis was used to determine the Lys:ME ratio that maximized ADG and G:F over the 35 or 49-d test periods for Exp. 1 and 2, respectively. In Exp. 1 increasing Lys:ME increased ADG (linear P=0.07, quadratic P=0.02) and G:F (linear P=0.09, quadratic P=0.02) in control pigs over 35-d. In PRRSV pigs, ADG and G:F increased linearly with increasing Lys:ME (P=0.001). The Lys:ME for optimum ADG and G:F during PRRSV challenge was 3.05 and 3.15, respectively, compared to 2.24 and 2.51, respectively, in control pigs using a one-slope broken-line model. In Exp. 2 control pigs became naturally infected after 21 dpi. Prior to infection, ADG and G:F increased with increasing Lys:ME in control pigs (linear P<0.001, quadratic P<0.05). The response was similar in PRRSV pigs (P<0.01, linear and quadratic). Over the 49-d period, increasing Lys:ME improved ADG (linear P<0.001) and G:F (linear P<0.001, quadratic P=0.02) in naturally infected pigs. The response was similar in experimental infection for ADG (linear P<0.001, quadratic P=0.04) and G:F (linear P=0.009). The optimum ratio for ADG was 2.90 and 3.16 for natural and experimental infection, respectively, using a one-slope broken-line model. Using a 2-slope broken-line model, a 3.12 and 3.17 Lys:ME maximized G:F for natural and experimental infection, respectively. In summary, increasing Lys:ME ratio by 110 to 120% improved performance and feed efficiency during a PRRSV challenge. This response was similar in experimental and natural PRRSV infections.