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The article discusses the process of purifying methacrylic acid (MAA) and its esters. It provides an overview and detailed description of the process. Also discussed are suitable materials of construction resistant to corrosion which may be used to handle methyl methacrylate (MMA) crude, one of which is the 300 series stainless steel. Optional processing additives which may be combined into the product column feed stream to improve removal of impurities are mentioned, including organic acids.

The article discusses a proposed method of manufacturing normal-butyl methacrylate (n-BMA) and i-butyl methacrylate (i-BMA) by transesterification of methyl methacrylate (MMA). N-BMA and i-BMA are acrylic monomers contributing to flexibility, weatherability, clarity and internal plasticization to the polymers in acrylic latexes. The proposed n-BMA process uses butanol (BuOH) and MMA as key raw materials. The procedures involved in the process such as reaction, light ends separation and heavy ends separation are described.

Fluorination of the hydrogen-terminated disilanes H[(p-XC6H4)SiMe]2H (X = H, F, OMe, Me) and H(ⁿBuSiMe)2H has been achieved with CuF2·2H2O in refluxing CCl4 to give fluorine-terminated oligomers initially as a 1:1 mixture of diastereomers. Higher yields of F[(p-XC6H4)SiMe]2F with fewer byproducts from silicon−silicon bond cleavage were achieved with CuCl2/CuI/KF in THF, and H(PhSiMe)3H was also successfully fluorinated with this mixture. Crystallization of the initially formed diastereomeric mixture of F[(p-XC6H4)SiMe]2F from solvent resulted in the isolation of the solid meso forms, while the mother liquors still contained the two diastereomers in an approximate 1:1 ratio. The enrichment of one of the diastereomers through crystallization meets the criteria for asymmetric transformation (AT). The structures of all four meso-F[(p-XC6H4)SiMe]2F compounds were determined by X-ray crystallography. Both fluoride and chloride salts cause epimerization of meso-F(ArSiMe)2F to a statistical mixture of meso and rac diastereomers.

Duplication and deletion of the 1.4-Mb region in 17p12 that is delimited by two 24-kb low copy number repeats (CMT1A-REPs) represent frequent genomic rearrangements resulting in two common inherited peripheral neuropathies, Charcot-Marie-Tooth disease type 1A (CMT1A) and hereditary neuropathy with liability to pressure palsy (HNPP). CMT1A and HNPP exemplify a paradigm for genomic disorders wherein unique genome architectural features result in susceptibility to DNA rearrangements that cause disease. A gene within the 1.4-Mb region, PMP22, is responsible for these disorders through a gene-dosage effect in the heterozygous duplication or deletion. However, the genomic structure of the 1.4-Mb region, including other genes contained within the rearranged genomic segment, remains essentially uncharacterized. To delineate genomic structural features, investigate higher-order genomic architecture, and identify genes in this region, we constructed PAC and BAC contigs and determined the complete nucleotide sequence. This CMT1A/HNPP genomic segment contains 1,421,129 bp of DNA. A low copy number repeat (LCR) was identified, with one copy inside and two copies outside of the 1.4-Mb region. Comparison between physical and genetic maps revealed a striking difference in recombination rates between the sexes with a lower recombination frequency in males (0.67 cM/Mb) versus females (5.5 cM/Mb). Hypothetically, this low recombination frequency in males may enable a chromosomal misalignment at proximal and distal CMT1A-REPs and promote unequal crossing over, which occurs 10 times more frequently in male meiosis. In addition to three previously described genes, five new genes (TEKT3, HS3ST3B1, NPD008/CGI-148, CDRT1, and CDRT15) and 13 predicted genes were identified. Most of these predicted genes are expressed only in embryonic stages. Analyses of the genomic region adjacent to proximal CMT1A-REP indicated an evolutionary mechanism for the formation of proximal CMT1A-REP and the creation of novel genes by DNA rearrangement during primate speciation.

Hydroclimatic variability in the tropical Pacific reflects large‐scale ocean‐atmosphere processes that imprint on global climate, but tropical Pacific hydroclimate variability over the last millennium remains uncertain. Here we present a multi‐proxy reconstruction from a lacustrine sediment record on Kiritimati Atoll that spans the last millennium. A lake salinity reconstruction from the δ2H values of total lipid extracts, combined with changes in sediment mineralogy and the stable isotopic composition of inorganic carbonates, indicate the presence of several distinct hydrologic regimes on Kiritimati, including a period of persistent aridity from 960–1030 CE, shorter episodes of aridity from 1030–1370 CE, and extreme aridity throughout the latter half of the last millennium, from 1370–1970 CE, that drove complete evaporation of the lake. A period of wetter, variable conditions defines recent decades. Compound‐specific lipid biomarker δ2H values indicate that shifts in microbial community structure occurred in the past, from a community dominated by photoautotrophic and chemoautotrophic organisms in more arid periods to a more metabolically diverse community in the recent period. Comparison of this record with nearby sediment records from Washington Island reveals a similar pattern of aridity through the last millennium, followed by wetter conditions in the modern period. These coherent changes in hydroclimate in the central Pacific are inconsistent with a migration of the Pacific Intertropical Convergence Zone within these latitudes. Rather, past aridity was caused by reduced El Niño‐Southern Oscillation variability, observed through the low‐pass filter of lacustrine records, or by multidecadal to multi‐century strengthening of the Pacific Walker Circulation. Paleo‐salinity record from Kiritimati indicates higher lake salinity in last millenniumPeriods of aridity synchronous across Line IslandsWetter but variable modern climate supports stronger modern El Niño‐Southern Oscillation Paleo‐salinity record from Kiritimati indicates higher lake salinity in last millennium Periods of aridity synchronous across Line Islands Wetter but variable modern climate supports stronger modern El Niño‐Southern Oscillation

Attachment between the sister chromatids is required for proper chromosome segregation in meiosis and mitosis, but its molecular basis is not understood. Mutations in the Drosophila ord gene result in premature sister chromatid separation in meiosis, indicating that the product of this gene is necessary for sister chromatid cohesion. We isolated the ord gene and found that it encodes a novel 55 kDa protein. Some of the ord mutations exhibit unusual complementation properties, termed negative complementation, in which particular alleles poison the activity of another allele. Negative complementation predicts that protein‐protein interactions are critical for ORD function. The position and nature of these unusual ord mutations demonstrate that the C‐terminal half of ORD is essential for sister chromatid cohesion and suggest that it mediates protein binding.

Shoshonitic magmatism occurred in transpressive geodynamic settings within the Superior Province during the diachronous accretion of allochthonous subprovinces over 2720 to 2680 Ma, which culminated in stabilization of this Archean craton. The dikes are interpreted to have formed from low degrees of partial melting of depleted mantle metasomatically enriched in LILE and LREE during a prior subduction-accretion event.

It is known that the intrarenal mean transit time (MTT) can be determined using renography by first deconvolving the kidney retention function from the obtained time–activity curve and then integrating the retention function. A direct and approximate calculational method, based on an integral mathematical model, has also been employed to estimate the MTT. In this work it is shown that the direct approximate method is equivalent to the standard deconvolution method applied with the assumption of a time independent retention function. Potential errors incurred using the direct method are thus quantified and assessed over a range of representative decay parameters.

Interstitial laser photocoagulation (ILP) destroys tumors thermally, using laser energy delivered from implanted optical fibers. The objectives of the study are to identify a fiber tipdelivered energy combination which produces lesions of useful size, visible on ultrasound (US) during ILP, and to compare ILP lesions and their US images.

Attachment between the sister chromatids is required for proper chromosome segregation in meiosis and mitosis, but its molecular basis is not understood. Mutations in the Drosophila ord gene result in premature sister chromatid separation in meiosis, indicating that the product of this gene is necessary for sister chromatid cohesion. We isolated the ord gene and found that it encodes a novel 55 kDa protein. Some of the ord mutations exhibit unusual complementation properties, termed negative complementation, in which particular alleles poison the activity of another allele. Negative complementation predicts that protein‐protein interactions are critical for ORD function. The position and nature of these unusual ord mutations demonstrate that the C‐terminal half of ORD is essential for sister chromatid cohesion and suggest that it mediates protein binding.

Previously described scattering based edge distortions in optical density scans obtained from a neutron radiographic knife-edge image have been here confirmed using analog Monte Carlo simulation. In an attempt to estimate the effects of additional object scatter on such artifacts, the effect on the edge response of diffusely incident neutrons has been determined both empirically and by Monte Carlo simulation. The diffuse neutron incidence has been found to diminish the relative magnitude of the distortion, offering explanation for the infrequent observation of the corresponding edge scattering halo artifacts. The potential of this edge distortion as a diagnostic indicator of the buildup factor in radiography is suggested and examined.

Two-dimensional imaging properties of locally isotropic and isoplanatic point spread functions are described in a general radiographic context. In particular, the radiographic response to a two-dimensional wedge-shaped object is shown to possess several properties which enable the identification of the wedge corner on the image, thereby alleviating the need for image enhancement techniques. Extensions to the location of flat-edged boundaries are also discussed. The potential dimensioning application of this analysis lies in the precise and objective location of points of interest on radiographs of more complex two-dimensional objects.

Mineral deposits are not evenly distributed through Earth history and examples of individual deposit classes are restricted to narrow time intervals over geological time. This pattern reflects direct links between long-term geodynamic cycles, which control styles of heat flow and magmatism, and metallogenic processes. Significant improvements in trace-element analytical techniques have led to refined understanding of igneous processes and the construction of comprehensive geodynamic models. These in turn permit increasingly sophisticated applications of igneous trace-element geochemistry in mineral deposit exploration. Analytical advances, principally ICP-MS, include lowered detection limits, increased numbers of elements analysed and greatly reduced turnaround times. Whereas early exploration applications of igneous trace-element analyses focused upon felsic rocks with high concentrations of elements such as Zr and Y, new methodologies allow routine analysis of incompatible elements at far lower abundances in mafic and ultramafic rock types. Multi-element normalised diagrams are useful aids in assessment of modern datasets and highlight those element-element systematics which can be used to monitor the possible effects of alteration and crustal contamination. Once data have been screened, the distinct geochemical signatures of individual geodynamic settings (ocean plateaus versus island arc) and subsettings (juvenile or mature arc) can be related to a given terrene's prospectiveness for particular deposit classes. Exploration programs cannot rely solely upon high-precision trace-element analyses. However, when used to complement traditional lithogeochemical pathfinder studies based on large numbers of low-precision analyses, mapping and geophysical investigations, the technique promotes accurate and cost-efficient geological evaluations at the regional to the local scale.

Summary Archean shoshonitic lamprophyres are cotemporal and cospatial with gold mineralization in the Superior Province of Canada, both being emplaced along translithospheric structures that demark subprovince boundaries. By analogy with geochemically similar Phanerozoic counterparts, the dikes are a product of specific plate interactions rather than a deep asthenosphere plume-initiated event, and their onset in the late-Archean at ~ 2.7 Ga signifies that Phanerozoic style plate-tectonics was operating at this time. Fresh shonshonitic dikes are characterized by normal background gold contents of 3.9 ± 8.1 ppb (ls), close to the value of 3.0 ppb for the bulk continental crust, and average abundances of As, Sb, Bi, W, TI, B, Cu, Pb, Zn, and Mo are also close to their values in bulk continental crust. Thus, fresh lamprophyres are not intrinsically enriched either in Au or elements affiliated with gold in mesothermal deposits, and accordingly do not constitute a special source rock. Platinum group element contents (Ir = 0.4 ± 0.58 ppb; Pt = 5.9 ± 26.5, Pd = 5.5 ± 1.8), in conjunction with Cu, Au, and Ni abundances, define approximately flat patterns on primitive mantle-normalized diagrams, consistent with derivation of the alkaline magmas from a depleted mantle source variably enriched by incompatible elements. Comparable abundances and ratios of Pd/Au, Os/Ir, and Ru/Ir in Archean lamprophyres, Archean komatiites, and Gorgona komatiites signify that the Archean and Phanerozoic upper mantle had similar noble metal contents, such that the prolific greenstone belt Au-Ag vein deposits cannot be explained by secular variations in upper mantle Au abundance alone. The lack of covariation between Au and light rare earth elements in lamprophyres rules out mantle metasomatism as a process generating intrinsically Au-rich magmas.

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Reaction of H(ArMeSi)2H (Ar = C6H5, 1a; p-CH3C6H4, 1b; p-FC6H4, 1c; p-MeOC6H4, 1d) with CuF2·2H2O provides F(ArMeSi)2F, 2a−d, as a 1:1 mixture of diastereomers. meso-2a, 2b, and 2c crystallize from a hexane solution of the diastereomeric mixture, leaving a mother liquor that still contains a rac/meso ratio near 1:1. Partial conversion of the rac/meso mixture of 2d to meso-2d occurred during recrystallization from ⁱPrOH. Reaction of meso-2 with catalytic quantities of ionic fluoride sources results in formation of a statistical mixture of meso/rac-2.

TO THE EDITOR:— The council of the Wayne County Medical Society announces its course of action relative to the program of maternal and pediatric care for wives and infants of enlisted men projected by the government under H. R. 1975 and proposed to be administered by the state department of health.The council believes that all the families of men in military service requiring assistance for any of the necessities of life should receive a direct contribution from the federal government and that the money thus appropriated should be paid directly to those for whom it was intended, namely the wives and children of men in the armed forces.The council believes that the proposed plan under H. R. 1975 is inadequate in its scope because it is restricted to one particular condition in the mother and to the care of children up to only 1 year of age; furthermore,