Insights into carbon nanotube and graphene formation mechanisms from molecular simulations: a review.

The discovery of carbon nanotubes (CNTs) and graphene over the last two decades has heralded a new era in physics, chemistry and nanotechnology. During this time, intense efforts have been made towards understanding the atomic-scale mechanisms by which these remarkable nanostructures grow. Molecular simulations have made significant contributions in this regard; indeed, they are responsible for many of the key discoveries and advancements towards this goal. Here we review molecular simulations of CNT and graphene growth, and in doing so we highlight the many invaluable insights gained from molecular simulations into these complex nanoscale self-assembly processes. This review highlights an often-overlooked aspect of CNT and graphene formation-that the two processes, although seldom discussed in the same terms, are in fact remarkably similar. Both can be viewed as a 0D â†’ 1D â†’ 2D transformation, which converts carbon atoms (0D) to polyyne chains (1D) to a complete sp(2)-carbon network (2D). The difference in the final structure (CNT or graphene) is determined only by the curvature of the catalyst and the strength of the carbon-metal interaction. We conclude our review by summarizing the present shortcomings of CNT/graphene growth simulations, and future challenges to this important area.

Deuterium uptake in magnetic-fusion devices with lithium-conditioned carbon walls.

Lithium wall conditioning has lowered hydrogenic recycling and dramatically improved plasma performance in many magnetic-fusion devices. In this Letter, we report quantum-classical atomistic simulations and laboratory experiments that elucidate the roles of lithium and oxygen in the uptake of hydrogen in amorphous carbon. Surprisingly, we show that lithium creates a high oxygen concentration on a carbon surface when bombarded by deuterium. Furthermore, surface oxygen, rather than lithium, plays the key role in trapping hydrogen.

Melanogenic effect of dersimelagon (MT-7117), a novel oral melanocortin 1 receptor agonist.

Background: The activation of melanocortin 1 receptor (MC1R) on melanocytes stimulates the production of eumelanin. A tridecapeptide α melanocyte-stimulating hormone (αMSH) is known to induce skin pigmentation. Objectives: We characterised the properties of a novel oral MC1R agonist dersimelagon (MT-7117) with respect to its specific binding to MC1R, downstream signalling and eumelanin production in experimental models. Methods: The competitive binding and production of intracellular cyclic adenosine 3', 5'-monophosphate in cells expressing recombinant melanocortin receptors were examined. A mouse melanoma cell line B16F1 was used for the evaluation of in vitro melanin production. The in vitro activity of MT-7117 was determined with αMSH and [Nle4, D-Phe7]-αMSH (NDP-αMSH) as reference comparators. The change of coat colour and skin pigmentation were evaluated after repeat administration of MT-7117 by oral gavage to C57BL/6J-Ay/+ mice and cynomolgus monkeys, respectively. Results: MT-7117 showed the highest affinity for human MC1R compared to the other melanocortin receptors evaluated and agonistic activity for human, cynomolgus monkey and mouse MC1R, with EC50 values in the nanomolar range. In B16F1 cells, MT-7117 increased melanin production in a concentration-dependent manner. In vivo, MT-7117 (≥0.3 mg/kg/day p.o.) significantly induced coat colour darkening in mice. MT-7117 (≥1 mg/kg/day p.o.) induced significant skin pigmentation in monkeys and complete reversibility was observed after cessation of its administration. Conclusions: MT-7117 is a novel oral MC1R agonist that induces melanogenesis in vitro and in vivo, suggesting its potential application for the prevention of phototoxic reactions in patients with photodermatoses, such as erythropoietic protoporphyria and X-linked protoporphyria.

Evaluation of the stability of Yamakagashi (Rhabdophis tigrinus) Equine Antivenom after 20 years storage.

In 2000, an equine Yamakagashi (Rhabdophis tigrinus) antivenom (Lot 0001) was testmanufactured as an unapproved drug for treatment of Yamakagashi bites. It was stocked on the premise of super-legal use from the viewpoint of emergency health crisis management. The antivenom showed a strong neutralizing ability against the hemorrhagic and coagulation activity of the Yamakagashi venom in its potency test. One vial of the antivenom can effectively neutralize at least about 4 mg of Yamakagashi venom. Its efficacy has also been confirmed in patients with severe cases of R. tigrinus bite that has been used in emergency. In 2020, this antivenom (Lot 0001) has reached 20 years after its production. To evaluate the integrity and potency of the antivenom, quality control, safety and potency tests had been conducted almost every year since 2012. Physical and chemical tests (property test, moisture content test, insoluble foreign matter test, osmotic pressure ratio test, pH test, protein content test, endotoxin test, sterility test) of the antivenom, showed no significant changes throughout the years, when compared to the results immediately after its production in 2000. All the parameters measured were also within the standard values. In animal safety tests (test for absence of toxicity and pyrogen), there was no change in the test results during the storage period and no abnormalities were observed. The potency test (anti-coagulant activity) after 20 years of the product, showed the same potency as those recorded immediately after production. Therefore, in all of the stability monitoring tests conducted so far, the product did not show any significant change compared to the results immediately after production. This confirms the stability of the product during the stockpiling period to the present, that is, 20 years after production.

[Antibody levels for diphtheria, tetanus and pertussis in young adult females immunized with whole cell pertussis-diphtheria-tetanus toxoid vaccine in infancy].

Antibody levels for diphtheria, tetanus and pertussis in 84 young adult females were measured. They had been immunized with whole cell pertussis-diphtheria-tetanus toxoid (DTwP) vaccine as a routine immunization in their infancy. Their history of DTwP vaccination were confirmed in their Maternal and Child Health Handbook, which includes their immunization record. Among the 84 cases, 4 cases (4.7%) had been immunized with the first dose of DTwP, 5 cases (6.0%) with the second dose, 23 cases (27.4%) with the third dose and 52 cases (61.9%) with the fourth dose. Of the 84 cases, 89.3% had received DTwP vaccine more than the third dose. In the 15-19 years after the last DTwP vaccination, the antibody positive rate for diphtheria and tetanus (> or = 0.01 IU/ml) were 86.9% and 94.0%, respectively. On the other hand, antibody positive rate for anti-pertussis toxin (anti-PT) and anti-filamentous hemaggulutinin (anti-FHA) (> or = 10 EU/ml) were 35.7% and 55.9%, respectively. The positive rate for pertussis compared with those for diphtheria and tetanus were lower. These findings suggested that DTwP vaccination in infancy does not provide sufficient immunity for young adults against pertussis, but DTwP vaccination provides adequate immunity against diphtheria and tetanus.

Characterization and clinical study on the acellular pertussis vaccine produced by a combination of column purified pertussis toxin and filamentous hemagglutinin.

Bordetella Pertussis Tohama phase I was cultured in a 300-liter fermentor using a medium containing 0.1% heptakis (2,5-0-dimethyl) beta-cyclodextrin (MeCD). Pertussis toxin (PT) and filamentous hamagglutinin (FHA) were purified using affinity and ion exchange gel column chromatographies. Endotoxin contents of these antigens (10 micrograms PN/ml) were less than 10 ngLPS/ml. PT and FHA were independently treated with formalin in the presence of amino acid and were mixed at a protein concentration ratio of 1:4, the same ratio of our commercialized acellular pertussis vaccine. PDT vaccine containing 2 micrograms PN of PT and 8 micrograms PN of FHA per milliliter was prepared. This PDT vaccine satisfied all the items of the Japanese Minimum Requirements including potency and toxicity tests. Even after this vaccine was incubated for 4 weeks at 37 degrees C, no deaths of the inoculated mice were observed after challenge with 4 mg of histamine on the 4th and 12th day of the inoculation. Compared with the conventional vaccine, this new vaccine caused less swelling in the mouse footpad test. A field trial of our two vaccines, one manufactured by the conventional method (lot No. 21A) and the other produced by the new method (lot No. KC8702), revealed that children receiving KC8702 showed almost the same anti-PT and anti-FHA antibody levels as those given 21A. Those who received KC8702 suffered from less local side effects such as redness, swelling or induration than those given 21A. Our new method for the production of acellular pertussis vaccine permits us the economical manufacturing of the vaccine with uniform quality in a closed system.

Ion chemistry of NOO+.

The kinetics for the reactions of NOO+ ions with neutral molecules having ionization potentials (IPs) from 9.27 to 15.58 eV was measured in a selected ion flow tube at 298 K. The NOO+ ions are produced from the reaction of N3+ + O2 and have been reacted with the following: NO, C6F6, CS2, CF3I, C3F6, OCS, C2H6, Xe, SO2, O3, N2O, CO2, Kr, CO, D2, and N2. Numerous types of reactions were observed with the various neutral reagents, including production of NO+ (which may involve loss of an O from the ion or addition of O to the neutral reactant, although the two channels could not be distinguished here), charge transfer, isomerization of NOO+ to ONO+, and hydride abstraction. High level theoretical calculations of the structures and energetics of the various isomers, electronic states, and transition states of NOO and NOO+ were performed to better understand the observed reactivity. All neutral species with an IP< or =11.18 eV were observed to react with NOO+ in part by charge transfer. Detailed calculations showed that the recommended adiabatic and vertical IPs of NOO are 10.4 and 11.7 eV, respectively, at the MRCISDQ/AVQZ level of theory. The observed experimental limit for charge transfer of 11.18 eV agreed well with the energetics of the final products obtained from theory if dissociation of the neutral metastable product occurred, i.e., the products were X+ +[O(3P) + NO(2Pi)], where [O(3P)+NO(2Pi)] formed via dissociation of metastable NOO. Charge exchange with neutral reagent X would, therefore, be exothermic if IP(X)<[IPad(NOO)-DeltaE(O+NO)-NOO]= approximately 11.1 eV, where IPad(NOO) is the adiabatic IP. The potential energy surface for the reaction of NOO+ with C2H6 was also calculated, indicating that two pathways for formation of HNO2 + C2H5 (+) exist.

Amino acid sequences of the tryptic peptides from carboxymethylated L-asparaginase from Escherichia coli.

S-Carboxymethylated L-asparaginase was digested with trypsin and the resulting peptides were isolated by using gel filtration, ion exchange column chromatography and paper chromatography. Among the peptides thus isolated, 27 peptides were considered not to overlap and the sum of the amino acids from these 27 peptides is in good agreement with amino acid composition of the enzyme. The amino acid sequences of the peptides were determined by fragmentation with various enzymes and subtractive Edman degradation.

Theoretical studies of biological nitrogen fixation. I. Density functional modeling of the Mo-site of the FeMo-cofactor.

The Mo-site and its ligand environment of the FeMo-cofactor (FeMo-co) were studied using the hybrid density functional method B3LYP. The structure and stability of the model complex (S-ligand)3(N-ligand)Mo[(S)-OCH(CH3)C(O)O-] along with its various protonated and reduced/oxidized forms were calculated. Several hypotheses were tested: (i) ligand environment of the Mo-site, (ii) monodentate vs bidentate coordination of the Mo-bound homocitrate ligand, (iii) substrate coordination to the Mo center, and (iv) Mo-His interaction. It was found that the decoordination of one of the homocitrate (lactate in the model) "legs", the bidentate-->monodentate rearrangement, does not occur spontaneously upon either single/double protonation or one-electron reduction. However, it could occur only upon substrate coordination to the Mo-center of the single-protonated forms of the complex. It was shown that one-electron reduction, single-protonation, and substrate coordination facilitate the bidentate<-->monodentate rearrangement of the homocitrate (lactate) ligand of FeMo-co. It was demonstrated that the smallest acceptable model of His ligand in FeMo-co is methylimidazolate (MeIm-). Our studies suggest that the epsilon-N of the FeMo-co-bound His residue is not protonated, and as a consequence the cluster is tightly bound to the protein matrix via a strong Mo-N delta bond.

Simple, speedy, sensitive, and specific serodiagnosis of pertussis by using a particle agglutination test.

We developed a particle agglutination test (KPA) with poly(gamma-methyl L-glutamate) as the solid particle for measurement of pertussis toxin (PT) antibody. In this study, KPA was assessed as a means of serodiagnosing pertussis, and the results were compared with those of indirect enzyme-linked immunosorbent assay (indirect ELISA) and the microagglutination test. First, four serum samples were collected from each of 21 healthy children: before and 4 weeks after receiving three primary doses of acellular pertussis vaccines and before and 4 weeks after receiving a booster dose. In all 21 vaccinees, a significant rise in PT antibody titers was observed by KPA after each vaccination, and among all 84 serum samples collected, an excellent correlation was demonstrated between the values obtained by indirect ELISA and those obtained by KPA (r = 0.92). Second, paired serum samples were collected at intervals of approximately 2 weeks from 51 patients with culture-confirmed pertussis. A significant increase in titer (fourfold or more) was observed in 39 (76%) patients by KPA, 34 (67%) patients by indirect ELISA, and 23 (45%) patients by the microagglutination test. In acute- and convalescent-phase sera collected from 20 nonpertussis patients, there were no changes in titers by KPA. The KPA procedure was as simple as that of the microagglutination test, and the reaction time was only 2 h (or overnight). In this study, KPA was demonstrated to be a simple, speedy, sensitive, and specific serodiagnostic method for pertussis.

Enhancing effects of pertussis toxin B oligomer on the immunogenicity of influenza vaccine administered intranasally.

Influenza vaccines together with pertussis toxin B oligomer (PTB) purified from a culture supernatant of Bordetella pertussis were administered intranasally into mice to test for an adjuvant effect of the PTB. An inactivated virus vaccine and an ether-treated HA vaccine prepared from influenza virus A/Yamagata/120/86 (H1N1) and formulated with PTB, stimulated production of serum haemagglutinin inhibition (HI) antibody and pulmonary and endotracheal secretory IgA antibody to high titres. In addition, mice immunized with the influenza vaccines formulated with PTB were protected against exposure with a challenge virus. These results demonstrate that PTB can enhance the immunogenicity of influenza vaccines administered intranasally.

Identification of dimethylbenzimidazole axial coordination and characterization of (14)N superhyperfine and nuclear quadrupole coupling in Cob(II)alamin bound to ethanolamine deaminase in a catalytically-engaged substrate radical-Cobalt(II) biradical state.

Cobalt(II)-(14)N superhyperfine and (14)N nuclear quadrupole couplings in cryotrapped free and ethanolamine deaminase-bound cob(II)alamin have been characterized in the disordered solid state by using X-band electron spin-echo envelope modulation (ESEEM) spectroscopy. Enzyme-bound cob(II)alamin was cryotrapped after formation by substrate-initiated, thermally activated cleavage of the cobalt-carbon bond of adenosylcobalamin. Free dimethylbenzimidazole axial base-on cob(II)alamin was formed by photolysis of the corresponding adenosylcobalamin and cryotrapped in glycerol-aqueous glass. Three-pulse ESEEM experiments were performed by using microwave pulse excitation at the g( perpendicular) value of Co(II) at magnetic field values of 287.0 and 345.0 mT and over a range of tau values from 227 to 1316 ns. Two common sets of (14)N features are distinguished in the ESEEM spectra. One set is assigned to the remote (N1) nitrogen in the dimethylbenzimidazole alpha-axial ligand by using two independent approaches: (a) comparison of ESEEM from cob(II)alamin with ESEEM from cob(II)inamide-ligand model compounds and (b) from the correspondence between the N1 (14)N nuclear quadrupole parameters derived from ESEEM simulations and those computed by using density functional theory. The second set is assigned to the corrin ring (14)N nuclei. The results identify the coenzyme's on-board dimethylbenzimidazole moiety as the alpha-axial ligand to cob(II)alamin in ethanolamine deaminase in the substrate radical-Co(II) biradical catalytic intermediate state. Thus, Co(II) is a pentacoordinate, alpha-axial liganded complex during turnover. We infer that dimethylbenzimidazole is also the alpha-axial ligand to the intact coenzyme in the resting enzyme. A 14% increase in the isotropic hyperfine coupling of the remote dimethylbenzimidazole (14)N nucleus in enzyme-bound versus free base-on cob(II)alamin shows an enhanced delocalization of unpaired spin density from Co(II) onto the axial ligand, which would contribute to the acceleration of the cobalt-carbon bond cleavage rate in situ.

Comparison of the protective effects of the pertussis acellular vaccine with the component vaccine, which have different amounts of fimbriae, against the experimental aerosol infection of mice with Bordetella pertussis.

We obtained highly purified fimbrae from Bordetella pertussis cells which gave a single band in SDS-polyacrylamide gel electrophoresis. Using the purified fimbriae, we prepared anti-fimbriae rabbit or goat IgGs by fimbriae-Sepharose affinity chromatography, and developed ELISA for its determination. The concentration of fimbriae in our former type of acellular vaccine (80 micrograms per ml) was determined to be 20 ng per ml, and that in our component vaccine was at an almost negligible level. To estimate the protective effects of the small levels of fimbriae, we evaluated the protective activities of three types of vaccines; the former type acellular vaccine (pertussis toxin (PT): filamentous hemagglutinin (FHA): fimbriae = 15:61:0.02 (microgram per ml)), the two-component vaccine (16:64:0.0001), and the three-component vaccine (16:63:0.8). The three types of vaccines showed no significant differences in protectivity against the experimental aerosol infection suggesting that these levels of fimbriae are not effective against the experimental aerosol infection of mice with Bordetella pertussis.

Ion-molecule rate constants and branching ratios for the reaction of N(3) (+)+O(2) from 120 to 1400 K.

The kinetics of the reaction of N(3) (+) with O(2) has been studied from 120 to 1400 K using both a selected ion flow tube and high-temperature flowing afterglow. The rate constant decreases from 120 K to approximately 1200 K and then increases slightly up to the maximum temperature studied, 1400 K. The rate constant compares well to most of the previous measurements in the overlapping temperature range. Comparing the results to drift tube data shows that there is not a large difference between increasing the translational energy available for reaction and increasing the internal energy of the reactants over much of the range, i.e., all types of energies drive the reactivity equally. The reaction produces both NO(+) and NO(2) (+), the latter of which is shown to be the higher energy NOO(+) linear isomer. The ratio of NOO(+) to NO(+) decreases from a value of over 2 at 120 K to less than 0.01 at 1400 K because of dissociation of NOO(+) at the higher temperatures. This ratio decreases exponentially with increasing temperature. High-level theoretical calculations have also been performed to compliment the data. Calculations using multi-reference configuration interaction theory at the MRCISD(Q)/cc-pVTZ level of theory show that singlet NOO(+) is linear and is 4.5 eV higher in energy than ONO(+). A barrier of 0.9 eV prevents dissociation into NO(+) and O((1)D); however, a crossing to a triplet surface connects to NO(+) and O((3)P) products. A singlet and a triplet potential energy surface leading to products have been determined using coupled cluster theory at the CCSD(T)/aug-cc-pVQZ level on structures optimized at the Becke3-Lee, Yang, and Parr (B3LYP)/aug-cc-pVTZ level of theory. The experimental results and reaction mechanism are evaluated using these surfaces.

Further evaluation of the pertussis component vaccine produced by apoceruloplasmin affinity chromatography.

The heat-treated apoceruloplasmin (Apocp) is a useful protein as an affinity ligand for the purification of pertussis toxin (PT). The amounts of Apocp in the purified antigens or the pertussis component vaccine were determined. Anti-Apocp antibodies were not detected by the passive cutaneous anaphylaxis (PCA) test in rats. No anti-Apocp antibody was detected after hyperimmunization of rabbits with the vaccine. Apocp was not detected in PT and filamentous hemagglutinin (FHA) by ELISA using rabbit anti-Apocp IgG. In the experiments using 125I-labelled Apocp, 125I-Apocp was not detected in either PT or FHA which were purified by 125I-labeled Apocp-Sepharose, DEAE Sepharose, and cellulose sulfate chromatography. The contents of human DNA were also determined to be less than 10 pg per 1 mg of Apocp, by the dot-blot hybridization method using the 32P-labeled DNA probe of Alu sequence. In the tests for the presence of inapparent viruses, HBs antigen and HTLV-III antibody, no contamination was found in either the Apocp or in the vaccine. Large amounts of various viruses, which were intentionally added to the Apocp (spiking test), were completely inactivated by heating at 65 degrees C for 18 hr. Both the Apocp and the vaccine passed the general pharmacology and acute toxicity tests. From these results, the heat-treated Apocp was considered to be a suitable affinity ligand for the purification of the antigens for the pertussis component vaccine.

Ovalbumin coupled either with murine red blood cells or liposome induces IgG but not IgE antibody production.

Ovalbumin (OVA) was coupled with murine red blood cells (MRBC) using glutaraldehyde. The OVA-MRBC conjugate induced anti-OVA IgG antibody in mice at almost the same level as OVA in alum. However, no IgE antibody production specific for OVA was observed in OVA-MRBC-injected mice. A significant increase in IGG2a production was obtained with OVA-MRBC immunization, whereas the production of IgG1 predominated in OVA in alum immunization. Am OVA-liposome conjugate induced IgE-specific unresponsiveness in mice in the same manner as OVA-MRBC. Similar results were obtained when antigens other than OVA, such as tetanus toxoid or diphtheria toxoid, were coupled to liposome. These results show the potential of antigen-liposome conjugates for the development of vaccine that induces sufficient IgG antibody production without IgE synthesis.

Mucosal immunization against hepatitis B virus by intranasal co-administration of recombinant hepatitis B surface antigen and recombinant cholera toxin B subunit as an adjuvant.

Recombinant cholera toxin B subunit (rCTB) produced by Bacillus brevis carrying pNU212-CTB has been previously found to be a potent mucosal adjuvant to aluminium-non-adsorbed tetanus toxoid (nTT) and diphtheria toxoid (nDT) co-administered intranasally, and the possibility of needle-free inoculation of these vaccines with rCTB has been suggested. In this paper we examined the potentiality of rCTB as a mucosal adjuvant to aluminium-non-adsorbed yeast-derived recombinant hepatitis B surface antigen (rHBs) being a particulate antigen when administered intranasally with rCTB. In-house ELISA showed that a mixture of rHBs (1 or 5 microg) and rCTB (10 microg) elevated not only systemic responses but also mucosal immune responses at the nasal cavity, the lung, the saliva, the small intestine and the vagina against rHBs, and these could be further increased with higher doses of antigen. With antibody isotypes of IgG, there were equally high levels of serum HBs-specific IgG1, IgG2a and IgG2b antibodies and induction of mixed Th1- and Th2-type responses was considered to occur in combination of rHBs and rCTB. Serum anti-HBs titres in almost all mice obtained from sandwich EIA using a commercial kit were higher than 1000 milli-international units ml(-1) (mIU ml(-1)). These results show that rCTB is also very effective as a mucosal adjuvant for a particulate antigen like rHBs, as well as soluble antigens like nTT and nDT reported previously, suggesting the possibility of intranasal immunization with rHBs plus rCTB in humans.

Anti-tetanus toxoid antibody production and protection against lethal doses of tetanus toxin in hu-PBL-SCID mice.

BACKGROUND: In this study, severe combined immunodeficiency (SCID) mice, which permit the survival of lymphoid cells of human origin, were used to study the human anti-tetanus immune response. METHODS: Human peripheral blood lymphocytes (hu-PBL) obtained from 88 healthy donors (aged from 18 to 62) were transplanted into SCID mice, and anti-tetanus toxoid (Ttd) antibody production and protection against lethal doses of tetanus toxin (Ttx) were investigated in the hu-PBL-SCID mice. RESULTS: The transfer of human PBL evoked significant human anti-Ttd IgG antibody production for 37.5% of the donors. After in vivo immunization, the percentage of donors with PBL exhibiting positive anti-TtD IgG production in the mice increased to 54.5%. Mean anti-Ttd IgG levels in the sera were also significantly elevated in response to immunization. The mean IgG titer for the mice injected with PBL from donors under the age of 40 was significantly higher than that of the mice injected with PBL from donors aged 40 or older. Four weeks after the cell transfer, the mice were challenged with Ttx. The induction of protection against Ttx challenge was observed mostly in mice with PBL transferred from donors under the age of 40. In vivo immunization in SCID mice with Ttd increased the number of cases of resistance to Ttx. CONCLUSIONS: These results suggest that hu-PBL-SCID mice might serve as a tool for predicting the protective ability against pathogens in PBL donors and also for evaluating vaccine efficacy.