Mutational analysis of structure--activity relationships in human tumor necrosis factor-alpha

To determine the region of human tumor necrosis factor-alpha(TNF-), essential for cytotoxic activity against mouse L-M cells,single amino-acid-substituted TNF- mutant proteins (muteins)were produced in Escherichia coli by protein engineering techniques.An expression plasmid for TNF- was mutagenized by passage throughan E.coli mutD5 mutator strain and by oligonucleotide-directedmutagenesis. Approximately 100 single amino-acid-substitutedTNF- muteins were produced and assayed for cytotoxic activity.The cytotoxic activities of purified TNF- muteins, e.g. TNF-31T,-32Y, -82D, -85H, -115L, -141Y, -144K and -146E, were < 1%of that of parent TNF-. These results indicate that the integrityof at least four distinct regions of the TNF- molecule is requiredfor full biological activity. These regions are designated asfollows: region I, from position 30 to 32; region II, from position82 to 89; region III, from position 115 to 117; region FV, fromposition 141 to 146. In addition, TNF-141Y could not completelycompete with parent TNF- for binding to the receptor. This demonstratesthat region IV, and at least aspartk acid at position 141, mustbe involved in the TNF receptor binding site.     

New type of pressurized cultivation method providing oxygen for piezotolerant yeast

For efficient oxygen supply to pressurized culture, we developed a method using a highly pressurized membrane reactor with an air-saturated medium circulation system. The new method increased the cell growth of aerobic yeast approximately 20 folds larger than that in the case of using a conventional method.     

Direct Growth of Germanene at Interfaces between Van der Waals Materials and Ag(111)

Germanene, a 2D honeycomb germanium crystal, is grown at graphene/Ag(111) and hexagonal boron nitride (h-BN)/Ag(111) interfaces by segregating germanium atoms. A simple annealing process in N₂ or H₂/Ar at ambient pressure leads to the formation of germanene, indicating that an ultrahigh-vacuum condition is not necessary. The grown germanene is stable in air and uniform over the entire area covered with a van der Waals (vdW) material. As an important finding, it is necessary to use a vdW material as a cap layer for the present germanene growth method since the use of an Al₂O₃ cap layer results in no germanene formation. The present study also proves that Raman spectroscopy in air is a powerful tool for characterizing germanene at the interfaces, which is concluded by multiple analyses including first-principles density functional theory calculations. The direct growth of h-BN-capped germanene on Ag(111), which is demonstrated in the present study, is considered to be a promising technique for the fabrication of future germanene-based electronic devices.     

Polymerization of macromers

Summary The possibility of group transfer polymerization of methyl methacrylate-terminated polystyrene macromer (MA-PSt) was explored by using 1-methoxy-1-(trimethylsiloxy)-2-methyl-1-propene and tris(dimethylamino)sulfonium difluorotrimethylsilicate as initiator and catalyst, respectively. The results obtained at the polymerization temperature of 0°C were undesirable. However, the oligomerization at -78°C gave almost quantitatively oligo(MA-PSt) of which the degree of polymerization was in good agreement with the mole ratio of macromer to initiator. The GPC curve of oligo(MA-PSt) was sharp and symmetrical. In addition, it was shown by the copolymerization with methyl methacrylate that the polymerizability of the macromer was markedly enhanced in the presence of methyl methacrylate comonomer.     

Magnetite nanoparticles with high heating efficiencies for application in the hyperthermia of cancer

Magnetic hyperthermia is a safe method for cancer therapy. A gap-type alternating current magnetic field (100 kHz, 100–300 Oe) is expected to be clinically applicable for magnetic hyperthermia. In this study, magnetite nanoparticles (MNPs) varying in size from 8 to 413 nm were synthesized using a chemical coprecipitation and an oxidation precipitation method to find the optimum particle size that shows a high heating efficiency in an applied magnetic field. The particles' in vitro heating efficiency in an agar phantom at an MNP concentration of 58 mg Fe/ml was measured in an applied magnetic field. In a magnetic field of 120 Oe, the temperature increase (ΔT) of the agar phantom within 30 s was 9.3 °C for MNPs with a size of 8 nm, but was less for the other samples, while in a magnetic field of 300 Oe, ΔT = 55 °C for MNPs with a size of 24 nm, and ΔT = 25 °C for MNPs with a size of 8 nm. The excellent heating efficiency of MNPs with a size of 24 nm in a magnetic field of 300 Oe may be due to a combination of the effects of both relaxation and hysteresis losses of the magnetic particles. It is believed that MNPs with a size of 8–24 nm will be useful for the in situ hyperthermia treatment of cancer.     

Effect of W-Mo balance and boron nitrides on creep rupture ductility of 9Cr steel

The effect of W-Mo balance and boron nitrides (BN) on creep rupture ductility has been investigated for five heats of 9% Cr steel with 1.5% Mo equivalent, 0.003% boron and 0.05% nitrogen at 600^oC, 650^oC and 700^oC. The maximum time to rupture was 68,718 h at 650^oC. The reduction of area (RA) slightly decreases for up to about 8000 and 1000 h at 600 and 650^oC, respectively, while it significantly decreases above those. The BN particles are responsible for the degradation in RA at low stresses and long times by accelerating the formation of creep voids. At high stresses and short times, the RA decreases with increasing time to rupture and with increasing W concentration and concomitantly with decreasing Mo concentration. The rupture ductility is evaluated by using a semi-logarithmic diagram of the RA and total elongation, showing the necking dominant and void swelling dominant regions.     

Effect of fiber array irregularities on microscopic interfacial normal stress states of transversely loaded UD-CFRP from viewpoint of failure initiation

A detailed investigation has been carried out to determine the effect of local fiber array irregularities and controlling fiber distribution parameters on microscopic interfacial normal stress states for transversely-loaded unidirectional carbon fiber (CF)/epoxy composites. Linear elastic finite element analyses were carried out for two-dimensional image-based models composed of about 70 fibers. The relationship between the geometrical distribution of two adjacent fibers and the interfacial normal stresses (INSs) is investigated for all fibers in different image-based models. Three boundary conditions for loading were selected: Case A involved cooling from the curing temperature (the difference in temperature was ?155 K); Case B involved transverse loading of 75 MPa chosen as an example of macroscopic transverse fracture strength; and Case C involved both cooling from the curing temperature and transverse loading of 75 MPa. High compressive INSs due to the difference in the coefficients of thermal expansion are observed at the location of the shortest interfiber distance for Case A (cooling). High tensile INSs are observed at the location of the shortest interfiber distance and where the fiber alignment angle to the loading direction is small for Case B (loading). For Case C (cooling and loading), the high thermal residual compressive INSs and the high mechanical tensile INSs compensate each other, and the INSs at a short interfiber distance are much lower than those for Case B. These results clearly indicate the importance of the contribution of the thermal residual stresses to the transverse tensile failure initiation of CF/epoxy laminates.     

Effects of the introduction of the discrete energy loss process into Monte Carlo simulation of electron scattering

First, the single scattering model is briefly described. Next, the hybrid model is explained, which takes into consideration a part of the discrete energy loss processes. The Vriens or the Gryzinski cross section is used for core electron ionizations, and the Moller cross section for free electron excitations. The model is applied to the calculations of the energy distribution of transmitted electrons through a thin film and the depth distribution of generated x-rays. From comparisons among the calculated results with and without energy straggling and experimental data, it is found that the Gryzinski cross section shows the best result.     

Interaction of π-bonds of the silicon–silicon triple bond with alkali metals: An isolable anion radical upon reduction of a disilyne

The reduction of 1,1,4,4-tetrakis[bis(trimethylsilyl)methyl]-1,4-diisopropyltetrasila-2-yne 1 with an equivalent amount of alkali metal (Li, Na, K, KC₈) in THF produced the corresponding disilyne anion radicals 2a–c. Their EPR spectra are independent of the metals used in THF, indicating that the disilyne anion radical species exists as solvent-separated ion pairs in polar solvents. The one-electron reduction also occurred with potassium in toluene to produce the potassium salt of the anion radical 3, which was isolated as extremely air- and moisture-sensitive dark brown crystals. The molecular structure of 3 was established by X-ray crystallography, which showed that the potassium ion is solvated by one toluene molecule. The EPR spectrum of 3 in toluene showed the interaction of the anionic silicon atom with the K⁺ ion.