Incorporation of Halogenated Amino Acids into Antibody Fragments at Multiple Specific Sites Enhances Antigen Binding

Expansion of the amino-acid repertoire with synthetic derivatives introduces novel structures and functionalities into proteins. In this study, we improved the antigen binding of antibodies by incorporating halogenated tyrosines at multiple selective sites. Tyrosines in the Fab fragment of an anti-EGF-receptor antibody 059–152 were systematically replaced with 3-bromo- and 3-chlorotyrosines, and simultaneous replacements at four specific sites were found to cause a tenfold increase in the affinity toward the antigen. Structure modeling suggested that this effect was due to enhanced shape complementarity between the antigen and antibody molecules. On the other hand, we showed that chlorination in the constant domain, far from the binding interface, of Rituximab Fab also increased the affinity significantly (up to 17-fold). Our results showed that antigen binding is tunable with the halogenation in and out of the binding motifs.     

Chemical exposure and flammability risks of upholstered furniture

Upholstered furniture remains a consumer fire hazard. Flame retardant technologies are necessary but may present a health risk from chemical exposure. This study developed methodologies for measuring exposure to flame retardants and flammability performance, comparing the effectiveness of differing flammability reduction strategies on upholstered chairs with and without added flame retardants and the use of a barrier material. The chemical analysis focused on volatile organic compounds (VOCs) and flame retardants. Open flame tests were conducted on chair assemblies, and smolder resistance tests were conducted on chair materials. Results showed that VOC inhalation exposure during consumer use was low for all chair types. However, VOCs were significantly elevated during the chair burns. The organophosphorus flame retardant used in this study was found in air, settled dust and dermal transfer samples. The chairs with a barrier material demonstrated significantly lower flammability hazards when compared to the other chair types. All assembled chairs did not meet the criteria for smolder testing, suggesting a lack of correlation with open‐flame performance. This study demonstrated that combined human health and flammability advantages may be achieved for upholstered chairs constructed with an effective fire barrier material without any added flame retardants.     

Search for CDW in K metal

The fundamental question of whether the ground state of the alkali metals is a nearly-free-electron state or a charge-density-wave (CDW) state has remained unresolved for over 30 years, ever since Overhauser first suggested the possibility of a CDW ground state in these metals in 1962. For K metal, no evidence for CDW satellites was seen in x-ray measurements at 10 K (You et al., 1987). We made x-ray measurements for a K single crystal down to 50 mK. We observed the satellite-like spots at lower temperatures below about 10 K. We also measured the temperature dependence of the magnetic susceptibility between 1.8 K and 300 K by a SQUID magnetometer. Below about 20 K the magnetic susceptibility starts to decrease and below about 10 K it decreases more rapidly with decreasing temperature. We will discuss the possibility of CDW in K metal from our experimental results.     

Fabricating Nanocrystalline Diamond Ceramics by a Shock Compaction Method

Nanocrystalline diamond ceramics—namely, polycrystalline diamond compact consisting of ultrafine grains (one to hundreds of nanometers)—have been produced without any sintering additives via a shock compaction method using commercial diamond powders which consist of monocrystalline or shock-synthesized polycrystalline particles less than 1 μ in diameter. The method exploits plastic deformation of diamond and requires a precise spatial and timely partitioning of shock-induced thermal energy. Although much yet remains to be done for practical applications, the superior advantages of using ultrafine powders are supported by the experimental results and the theoretical modeling and considerations which are applicable to advanced ceramics.     

A model of Pt-Rh catalyst prepared by electro-chemical deposition of Rh ions on Pt(100) surface

When Pt-Rh(100) alloy surface was exposed to NO or O₂ at temperatures higher than 400 K, a characteristic p(3 × 1) LEED pattern appeared with segregation of Rh atoms on the surface. It was shown that when a Rh-deposited Pt(100) surface is heated in NO or O₂ the same 5 × 10^–8 Torr of H₂ at room temperature, the p(3 × 1) pattern disappears but is readily recovered 5 × 10^–8 Torr of H₂ at room temperature, the p(3 × 1) pattern disappears but is readily recovered by exposing to O₂ of 1 × 10^–7 Torr at room temperature. The growth of a Rh-O overlayer on Pt layer is responsible for the formation of the p(3 × 1) structure on either the Pt-Rh(100) alloy or Pt(100) surface, and this peculiar surface may correspond to the active surface of the Pt-Rh catalyst for NO _x reduction     

A New Catalyst for Selective Oxidation of CO in H2: Part 1, Activation by Depositing a Large Amount of FeO x on Pt/Al2O3 and Pt/CeO2 Catalysts

1% Pt/Al₂O₃ and 1% Pt/CeO₂ are markedly activated by the deposition of a large quantity of FeO _x , about 100 wt% in Fe with respect to the supports. In contrast, the activity of a Ru/Al₂O₃ catalyst was completely suppressed by the deposition of FeO _x , but a Ru-Pt/Al₂O₃ was markedly activated by the FeO _x . The activation depends on the sequence of the deposition, that is, no pronounced activation was observed on the Pt supported on a FeO _x /Al₂O₃ as well as on the Pt codeposited with a small amount of Fe on Al₂O₃, that is, the activity was almost equal to that of the Pt/Al₂O₃. The XPS analysis of the Pt/CeO₂ and FeO _x /Pt/CeO₂ proved that the Pt is effectively covered with the FeO _x . Selectivity for the oxidation of CO in H₂ was also improved on the FeO _x /Pt/Al₂O₃ and FeO _x /Pt/CeO₂ catalysts and it is rather independent of the conversion. In conformity with the feature of the FeO _x /Pt/Al₂O₃ and FeO _x /Pt/CeO₂ catalysts, we deduced that the deposited FeO _x is activated by the Pt and the FeO _x is responsible for the selective oxidation of CO.     

Charge integrating type position-sensitive proportional chamber for time-resolved measurements using intense X-ray sources

A position-sensitive detecting system for time-resolved diffraction measurements with very intensive X-ray sources has been developed. It consists of a charge integrating type gas-filled detector, multichannel analog multiplexers, a signal processor and a memory (120 ch.×128 phases×24 bits). The detector is 120 mm long in effective length by 10 mm×10 mm in cross section with a single anode of 20 μm diameter. One of the cathode planes consists of 120 cathode strips with a pitch of 1 mm. The spatial resolution is equal to the pitch under a certain detector current limit. The gas gain is adjustable to an appropriate value according to the X-ray intensity range of interest. For experiments with 8 keV X-ray sources, maximum absorption rates of 9×10⁷ photons/s·mm with low applied voltage and minimum absorption rates of about 3 photons/s·mm with high applied voltage can be achieved. This system was applied to a time-resolved X-ray diffraction study on frog muscle using a synchrotron radiation source at the Photon Factory and we could collect diffraction patterns with a time resolution of 10 ms and only 10 stimulations.     

Recent developments of rotary forming in Japan

Rotary forming is a method of forming various axisymmetric profiles by a rotary compressive process. This process has developed into an advanced technology capable of producing an ever growing range of products due to the recent developments of rotary forming machines. The recent trends of research and development of rotary forming in Japan are described.     

Oxygen induced direct hydrogenation of CO on Ni(100) surface

A trace amount of oxygen in H₂ promotes a new type of direct hydrogenation reaction of adsorbed CO on Ni(100) surface. The formation of H_xCO_y was suggested by high resolution electron energy loss spectroscopy (HREELS) and thermal desorption spectroscopy (TDS). HREEL spectra showed the formation of surface hydroxyl (OH) and the C-H bonds of H_iCO_y species but no carbonyl (C=O) loss peak was detected although thermal desorption yielded large amount of CO. The H _x CO _y undergoes the decomposition at 400–450 K on the hex-OH Ni(100) surface, which yielded CO, CO₂, H₂ and H₂CO. It was confirmed that no C-H bond formation occurs on c(2 × 2)-O, p(2 × 2)-O Ni(100) and hex-OH Ni(100) as well as on clean Ni(100) surfaces. This fact indicates that the gas phase oxygen may induce the direct hydrogenation of CO to form H _x CO _y , which is analogous to the hydrogenation of O to form hex-OH onNi(100).