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Principal component analysis and singular value decomposition (PCA and SVD) with self-modeling (SM) based on the van't Hoff equation constraint, were applied to 1,3-butadiene UV spectra measured in the 5.0−93.0 °C range. The shape of the resolved UV spectrum of the high-energy conformer of 1,3-butadiene is sensitive to broadening of the spectra of the individual conformers with increasing T. A simulated spectral set, in which temperature broadening was purposely included, was used to develop a procedure that allows precise recovery of the pure component spectra. A set of Gaussians is derived that, on convolution with the spectrum for each corresponding T, creates a uniformly broadened spectral set. Exact recovery of the “s-cis spectrum” from the simulated spectral set is accomplished. Treatments of the experimental spectra using this method yields a minor conformer 1,3-butadiene spectrum that is only slightly red-shifted relative to the s-trans-1,3-butadiene spectrum and is consistent with the s-gauche structure. Application of PCA-SM to the onsets of the simulated spectral set showed that temperature broadening does not significantly alter the conformer enthalpy difference derived from the best-fit van't Hoff plot (compare 3.00000 kcal/mol assumed with 2.99992 kcal/mol recovered). The experimental onset spectra give ΔH° = 2.926 kcal/mol, in excellent agreement with previously reported values.

Sequential immunoprecipitates show that H-2dm1 mutant cells express a hybrid "H-2D/L" antigen exhibiting determinants normally associated with two different gene products of the parental d haplotype-i.e., the H-2Dd and H-2Ld antigens. The hybrid H-2D/Ldm1 antigen appears to consist of a portion of the NH2-terminal extracellular half of the H-2Dd antigen "fused" to a portion of the COOH-terminal extracellular half of the H-2Ld antigen. This structure is inferred from the reactivity of dm1 antigens with cytotoxic T lymphocytes specific for H-2Ld determinants and with monoclonal antibodies specific for determinants in the structural domains of H-2Ld or H-2Dd. The H-2D/Ldm1 molecule apparently retains all of the third external domain (C2 or alpha 3) and part of the second external domain (C1 or alpha 2) of H-2Ld, but its first external domain (N or alpha 1) derives from H-2Dd. From these findings and from previous peptide mapping studies, we propose that the H-2D/Ldm1 antigen is the product of a hybrid gene that has resulted from an unequal crossover between the parental H-2Dd and H-2Ld genes, leaving the N exon and part of the C1 exon of the H-2Dd gene joined to the H-2Ld gene beginning somewhere within its C1 exon.

Significant cytotoxic lymphocyte-induced DNA fragmentation does not occur in four human target cells lysed by human natural killer lymphocytes, killer lymphocytes, or cytotoxic T lymphocytes. These results contrast with the extensive DNA fragmentation that occurs in murine target cells lysed by the analogous effector lymphocytes. Thus, DNA fragmentation, or the lack thereof, represents a species-specific difference between human and murine cells responding to lysis by cytotoxic lymphocytes. The DNase activity observed in murine cells is probably internally activated rather than delivered by the cytotoxic effector cells, since human killer lymphocytes selectively caused DNA fragmentation in murine but not in human target cells lysed by antibody-dependent cellular cytotoxicity.

A cDNA clone for an IgG-binding Fc receptor, rtFc gamma R alpha, of the rat natural killer cell line CRNK-16 is characterized here. This clone encodes an Fc gamma receptor as shown by the ability of cDNA-transfected COS cells to rosette IgG-coated sheep erythrocytes. The rtFc gamma R alpha is exceptionally homologous to the mouse moFc gamma R alpha, with 77% protein sequence identity and 71% nucleic acid identity overall. The transmembrane region of the rtFc gamma R alpha contains the sequence Leu-Phe-Ala-Val-Asp-Thr-Gly-Leu, which is present in the membrane sequences of four other Fc receptors including mouse Fc gamma R alpha, human Fc gamma RIII-2, and the Fc epsilon R alpha subunits of the rat and human high-affinity IgE-binding receptors. Also, the rtFc gamma R alpha cytoplasmic domain exhibits specific homology to other receptors derived from natural killer cells, human Fc gamma RIII-2 and mouse Fc gamma R alpha. However, the rtFc gamma R alpha cDNA clone is complementary to at least two different-sized mRNAs expressed by CRNK-16 cells, contrasting the single Fc gamma R-related mRNA species expressed by human and mouse natural killer cells. These rat mRNAs are homologous to both the 5' and the 3' end of the cDNA clone, suggesting that they may be (i) splice variants of one transcript or (ii) products of different but highly related genes.

After reduction by dithiothreitol and removal of the reductant by molecular sieve chromatography, the four interchain disulfide bonds of the human IgGlk protein Fro reoxidize in the presence of oxygen and trace metal ions. The six molecular components of the reoxidation--L (light chain), H (heavy chain), HL, H2, H2L, H2L2--are quantitatively determined from polyacrylamide gels containing sodium dodecyl sulfate and the time-dependent sulfhydryl titer is measured with 5,5'-dithiobis-(2-nitrobenzoic acid). The rates of H2L2 covalent assembly depend on pH in an unexpected way: If the reduced protein is chromatographed at pH 3.2 and then adjusted to pH 7.5 (25 degrees, ionic strength equals 0.14), H2L2 formation proceeds rapidly, with half-times ranging between 20 and 40 min. In contrast, if chromatography is carried out at pH 5.5 before adjusting to the same final conditions, the half-times for H2L2 formation are considerably longer (120-180 min). The half-times in the former case approach the somewhat faster rates of H2L2 assembly observed in pulse-chase experiments with various types of mouse, IgG-producing cells [Baumal, et al. (1971) J. Exp. Med. 134, 1316-1334]. To facilitate comparison of experiments and models, we plot the concentrations of the six components against the corresponding number of sulfhydryl equivalents per mole of Fro. The respective plots for the pH 3.2 leads to 7.5 and 5.5 leads to 7.5 experiments are very similar despite the rate differences. Moreover, these plots differ significantly from the calculated plot for a hypothetical random reoxidation in which the intrinsic probability for formation of each correct HL and H2 disulfide bond is assumed equal and independent. It is concluded that the in vitro reoxidation of Fro (i) is other than random; (ii) involved a pathway of pathways with HL, H2, and H2L precursors; and (iii) involves at least some kinetic cooperativity in bond formation, since no model bases solely on independent bond formation adequately accounts for the results. The models were used also to examine the cellular assembly pathways of mouse IgG proteins.

The mutagenicity of a benzene/methanol extract of fly ash from an atmospheric fluidized-bed combustor burning Beulah, N.D., lignite was tested in Salmonella. Six strains were used, including three that were mutants in a nitroreductase gene locus. The numbers of revertants from his- to his+ as a function of the amount of fly ash extracted were determined. The results showed that the major mutagens in the crude extract were nitro compounds, from the fact that reversion rates in the nitroreductase-deficient strains were significantly lower than in the parent strains from which they were derived. The responses of the three parental strains, TA 1538, TA98, and TA 100, were quite similar; thus no conclusions could be made about frameshift versus base-substitution mutagens. Mutagenicity of 15 fractions of the extract was also tested, and one major peak of activity was detected. This activity eluted from a high-performance liquid chromatograph outside the range of retention times associated with mononitro-aromatics. No further identification of specific nitroorganic compounds has been made.

This paper treats design of the built environment as a decision process and asserts the need for a more objective base for design decisions. A conceptual review of the designer's problem acknowledges the difficulty of resolving multiple objectives and considers the nature of the information available to the decisionmaker. The designer's formal design evaluation is related to the informal evaluations of the eventual users of his product. Users' responses are physiological, behavioural, and attitudinal. It is argued that the accumulating understanding of attitudinal responses to the built environment constitutes a potentially valuable information base for the designer's own evaluative decisions.

The quenching of trans-1-(2-anthryl)-2-phenylethene (t-APE) fluorescence by fumaronitrile (FN) was determined as a function of excitation wavelength (λexc) and temperature (5.0 ≤ T ≤ 80.0 °C). Principal component analysis with self-modeling (PCA-SM) was applied separately to the fluorescence spectra at each temperature. Resolved pure conformer fluorescence spectra were based on the condition that Stern−Volmer quenching constants for each conformer be λexc-independent. A shoulder at the blue edge of the spectra of the more extended, s-trans conformer (t-APEB) becomes more pronounced with increasing temperature revealing fluorescence from a thermally populated S2 state. Similar, but more subtle changes are evident in the spectra of the s-cis conformer (t-APEA). Both sets of resolved spectra exhibit blue shifts and broadening as the temperature is increased. These spectral changes are reflected in the shape of the eigenvectors obtained from the PCA of each set of spectra and prevent their resolution into S2 → S0 and S1 → S0 components. An earlier PCA-SM based resolution of a t-APE spectrothermal matrix into S1 → S0 fluorescence of t-APEA and S2 → S0, S1 → S0 fluorescence spectra of t-APEB is evaluated.

This paper introduces the theoretical basis for investigating obsolescence that has resulted from the preliminary stage of an ongoing research programme. A specification for model building is included.

A model is presented suggesting the interaction of CO2 and bicarbonate on lipids of the cell membrane. The interfacial tensions between water and oil (benzene) phases were measured using the stalagmometer and the sessile drop methods. Effects of electrolyte solutions and of CO2 on molecular arrangement at the interface were calculated. Chloride solutions against oleic acid in benzene produced little decrease in interfacial tension from that measured for pure water against the oil phase. Presence or absence of CO2 caused no change in interfacial tension of water or chloride solutions against the oil phase. Bicarbonate salts in the absence of CO2 caused marked decreases in interfacial tension from that measured for water or chloride solutions. Concomitant with this decrease in interfacial tension were an increase in hydration of the interface and changes in molecular spacings of the lipid. This hydration may be considered as reflecting a more ionic-permeable cell membrane. The addition of CO2 to the bicarbonates caused an increase in interfacial tension of the model, approaching that of the chlorides, with decreased hydration of the interface. Viewed as occurring at the cell membrane this would make the lipid more continuous and decrease the ease of ionic penetration. In this way the action of bicarbonates and CO2 at the interface suggests an explanation of the action of CO2 on the cell.