HCOOH Solution Research Articles

A rheological and optical properties investigation of aliphatic (nylon 66, PγBLG) and aromatic (kelvar, nomex) polyamide solutions

An experimental study of shear viscosity η(), principal normal stress difference N1(), storage modulus G′(ω), dynamic viscosity η′(ω), and filament elongation to break LB is reported for solutions of several polyamides; namely, nylon 66 in sulfuric acid (H2SO4) and formic acid (HCOOH), poly(γ-benzyl-L-glutamate) (PγBLG) in m-cresol, Nomex in H2SO4 and dimethylacetamide (DMA)/5% LiCl, and Kevlar in H2SO4 at 25 and 60°C. The variation of properties with concentration, polymer backbone and chain configuration, and solvent type is emphasized. The nylon 66/H2SO4 solutions have higher viscosity, normal stresses, and storage modulus than the HCOOH solutions of equivalent concentrations. The Nomex/H2SO4 solutions have higher viscosity and higher normal stresses and storage modulus than the DMA/LiCl solutions at equivalent concentrations. The significance of polymer chain backbone rigidity in forming liquid crystalline phases in Kevlar and PγBLG solutions is discussed and its influence on flow properties in indicated. These systems allow polarized light to pass through crossed polarizers and show maxima in viscosity–concentration data. The 25°C Kelvar solutions are distinctive in that they exhibit apparent yield stress values. This gives distinctive shear flow and oscillatory data. Filament elongation-to-break data show Kelvar > Nomex > nylon 66 in H2SO4 solutions for the order of spinnability.

The role of surface oxides in formic acid oxidation on Au

Compared to Pt or Pd electrodes, Au is a poor catalyst for the direct anodic oxidation of HCOOH, but the formation of Au surface oxides in acidic solutions is accompanied by a fast oxidation of HCOOH. This fast reaction is not simply a secondary reaction of Au surface oxides since those oxides are kinetically stable in HCOOH solutions. They do oxidize HCOOH only via a slow and purely electrochemical process which occurs on free Au sites and is “driven” by oxide reduction. The fast HCOOH oxidation is due to a highly reactive intermediate which is able either to form stable Au oxides Au n O m or to react with HCOOH. Our results are consistent with the model that by the charge transfer step a reactive non-equilibrium {Au…O> species is formed which converts to stable equilibrium oxides Au n O m after migration and rearrangement steps. Pre-equilibrium <Au…O> oxidizes HCOOH and this oxidation is of lower order with respect to <Au…O> compared with the formation of Au n O m .

Infrared spectroscopy of human amyloid fibrils and immunoglobulin proteins.

AbstractThe presence of the antiparallel‐β‐pleated sheet coformation io isolated human amyloid protein fibrils has been confirmed by infrared spectroscopy. In most amyloid samples, this conformation was enhanced by acidic solution conditions. Infrared spectroscopy (Amide I and Amide V absorption bands) and x‐ray diffraction methods were also used to examine the immunoglobulin molecule for solid state‐β‐structure. It was found that both heavy chains and Bence Jones proteins exhibited some β‐pleated sheet content upon acid and/or heat treatment. Furthermore, pepsin digests comprising either the variable‐rich region (Fd′) of the immunloglobulin heavy chain or in particular, filamentous variable segments of κ and λ Bence Jones proteins were, as isolated, very similar to amyloid in β‐structure content. Data from other immunoglobulin‐derived sample did not exhibit extensive β‐pleated sheet content. On the other hand, most amyliod and immunoglobulin‐derived samples did display some β‐structure when cast from 50% HCOOH solution. Under these conditions, however, filamentous light chain‐variable segments exhibited well‐defined infrared patterns rich in antiparallel‐β‐pleated sheet structure and gave a “cross‐β” x‐ray diffraction pattern.

パルプ，染色，漂白工業用不銹鋼の研究（第3報）

The immersion corrosion test were carried out on five kinds of austenitic stainless steels. The specimens were alloys of 23% Cr-20% Ni-1.5% Cu-1.5% Si-0.5% Mn, 23% Cr-20% Ni-2% Si-0.5% Mn, 23% Cr-20% Ni-3% Mo-3% Cu-0.5% Mn (clumin M3MC), 20% Cr-23% Ni-1.4% Mo-1.4% Cu-3% Si-0.5% Mn and 23% Cr-20% Ni-3% Mo-3% Cu-2% Si-0.5Mn. The corrosives were aqueous solutions of HCl, H2SO4, HNO3, CH3COOH, (COOH)2, HCOOH, Al2(SO4)3 Ca(OCl)2 and FeCl3 at 27°C and boiling aqueous solutions of HCl, H2SO4 and mixture of H2SO4 and HNO3.Results are as follows. (i) Alloys of 20% Cr-23% Ni-1.4% Mo-1.4% Cu-3% Si-0.5% Mn, 23% Cr-20% Ni-3% Mo-3% Cu-0.5% Mn had good acid-resistivities against HCl at 27°C temperature. (ii) All alloys were not been attacked at all in H2SO4, HNO3, CH3COOH, (COOH)2, HCOOH and aqueous solutions of Al2(SO4)3 and Ca(OCl)2 at a constant temperature. (iii) Alloys of 23% Cr-20% Ni-3% Mo-3% Cu-2% Si-0.5% Mn and 23% Cr-20% Ni-3% Mo-3% Cu-0.5% Mn had good acid-resistivities against HCl at boiling points. (iv) Alloys of 23% Cr-20% Ni-3% Mo-3% Cu-0.5% Mn and 20% Cr-23% Ni-1.4% Mo-1.4% Cu-3% Si-0.5% Mn and 23% Cr-20% Ni-3% Mo-3% Cu-2% Si-0.5% Mn were not attacked at all in mixture of H2SO4 and HNO3 at boiling points.