Electric-Field Induced Activation of Dark Excitonic States in Carbon Nanotubes.

Electrical activation of optical transitions to parity-forbidden dark excitonic states in individual carbon nanotubes is reported. We examine electric-field effects on various excitonic states by simultaneously measuring photocurrent and photoluminescence. As the applied field increases, we observe an emergence of new absorption peaks in the excitation spectra. From the diameter dependence of the energy separation between the new peaks and the ground state of E11 excitons, we attribute the peaks to the dark excited states which became optically active due to the applied field. Field-induced exciton dissociation can explain the photocurrent threshold field, and the edge of the E11 continuum states has been identified by extrapolating to zero threshold.

FWT and OBT concentrations in pine needle samples collected at Toki, Japan (1998-2012).

Free water tritium (FWT) and organically bound tritium (OBT) concentrations in pine needles have been investigated to understand the regional background tritium concentration in Toki City. Samples were regularly collected from pine trees on the National Institute for Fusion Science campus (1998-2012) and the nearby Shiomi Park (SP; 2002-12). FWT and OBT concentrations of the former samples ranged from 0.33 to 0.92 and 0.41 to 1.10 Bq l(-1), respectively, while those of the latter samples ranged from 0.32 to 0.86 and 0.33 to 0.79 Bq l(-1), respectively. Results of both sampling sites were almost the same, and they have been gradually decreased year by year. Concentration level of tritium for Toki City was close to the average background level in Japan. The OBT/FWT ratios were almost 1.0. The apparent half-life of FWT in this period was estimated as almost 10 y, and that of OBT was estimated as almost 12 y; these values were almost the same as the physical half-life.

Variation of atmospheric tritium concentration in three chemical forms at Toki, Japan: 2004-12.

Atmospheric tritium concentrations of HTO, HT and CH3T have been measured at Toki, Japan, for the environmental impact assessment of tritium for a fusion test facility. According to the data from 2004 to 2012, the concentrations of HT and HTO in water vapour tend to increase in spring. The seasonal variation in HT concentration at Toki was compared with the H2 concentration between 1990 and 2005 at Tae-ahn Peninsula, Republic of Korea, which is at approximately the same latitude as Toki. The monthly average of HT-specific activity varied from 1.24 × 10(5) to 1.76 × 10(5) TU. The peak of the monthly average H2 concentration did not match that of HT. This indicates that the mechanism of the production or the source of HT might be different from the production mechanism of H2.

sLORETA-qm for interictal MEG epileptic spike analysis: comparison of location and quantity with equivalent dipole estimation.

OBJECTIVE: To determine whether quantitative modification of a standardised low-resolution brain electromagnetic tomography (sLORETA-qm) could be used as a reliable tool for quantitative analysis of magnetoencephalography (MEG) for analysis of the interictal epileptic spike. To verify the performance of sLORETA-qm, magnetic source location and quantity were compared with the equivalent current dipole (ECD) method. METHODS: A total of 50 sources from 10 patients with epilepsy were obtained. Analyses were performed after the MEG data were 3-70 Hz band-pass filtered. Time points for analysis were selected referring to waveform patterns and the isofield contour map. With the same spherical model, source estimation was conducted with two methods of analysis: ECD and sLORETA-qm. Distance from the centre of the spherical model and intensities were compared between the methods. RESULTS: There were no significant differences between the methods in the distance from the spherical model (paired t-test, p=0.8761). Source intensities between the methods were strongly correlated (Spearman's Rho=0.9803, p<0.001). CONCLUSIONS: sLORETA-qm was closely correlated with ECD concerning point source location and quantity in analysis of the interictal epileptic spike. SIGNIFICANCE: sLORETA-qm is a reliable quantifiable method without arbitrariness for analysis of the interictal epileptic spike.

Significant relationship between local angle at fused segments and C2-7 angle: Average duration of longer than 20 years after anterior cervical discectomy and fusion.

BACKGROUND: The authors have focused their attention to the radiological durability of cervical sagittal alignment after anterior cervical discectomy and fusion (ACDF) using autologous bone grafting. MATERIALS AND METHODS: Among the patients who underwent ACDF with trans-unco-discal (TUD) approach between 1976 and 1997, 22 patients (16 males and 6 females) made return visits for a clinical evaluation. Patients with trauma or previously treated by anterior cervical fusion or by posterior decompression were excluded from the present study. Clinical evaluation included adjacent segment degeneration (ASD), osseous fusion, local angle at the fused segments and C2-7 angle of cervical spine. RESULTS: The duration after ACDF ranged from 13 to 34 years with an average of 21.3 ± 7.0 years. A single level fusion was done on 8 patients, 2 levels on 11 patients, 3 levels on 2 patients, and 4 levels on 1 patient. Imaging studies indicated that 12 of the 22 patients (54.5%) were graded as having symptomatic ASD. Osseous bony fusion at ACDF was recognized in all cases. None of the patients demonstrated kyphotic malalignment of the cervical spine. Average degrees of local angle at the fused segments and the C2-7 angle were 7.06 and 17.6, respectively. Statistical analysis indicated a significant relationship between the local at the fused segments and C2-7 angles. CONCLUSIONS: Sagittal alignment of the cervical spine was durable long after ACDF when the local angle at the fused segments was well stabilized.

Normal variation of diffusion tensor parameters of the spinal cord in healthy subjects at 3.0-Tesla.

AIMS: The purposes of the present study were to clarify the normal variation and to determine the normal reference values of diffusion tensor (DT) parameters (mean diffusivity [MD] and fractional anisotropy [FA]) of the spinal cord in single-shot fast spin-echo-based sequence at 3.0-Tesla (3T). MATERIALS AND METHODS: Thirty healthy subjects (mean age = 44.2 years, range = 20-72 years) were enrolled for this study. Mean values of MD and FA in six spinal levels (C2/3, C3/4, C4/5, C5/6, C6/7, and C7/Th1) were measured. Mean values, variances, and distributions of the MD and FA in each spinal level were analyzed. Age-dependent change of MD and FA as well as correlation between MD and FA was also analyzed. RESULTS: At all spinal levels, the values can be considered to be Gaussian distribution in MD but not in FA. A significant statistical negative correlation was observed between aging and the values of MD (r = 0.429, P = 0.018), but insignificant between the values of FA (P = 0.234). A slight significant statistical negative correlation was observed between the values of MD and FA (r = 0.156, P = 0.037). One way repeated measures analysis of variance indicated the significant difference between the spinal levels in both MD (P = 0.003) and FA (P < 0.0001). CONCLUSIONS: The analyzed data in the present study would be helpful for comparison when investigating the spinal condition of spinal disorders.

Evaluation of H*(10) using the developed spherical type neutron dose monitor.

An instrument for evaluating the neutron ambient dose equivalent has been developed. It has the characteristic of uniform response to wide energy of neutrons. The monitor is four-layered spherically shaped, based on moderation and absorption of neutrons. Neutron dose can be evaluated from the linear combination of three specific responses of thermoluminescent dosimeters (TLDs), which are located at three depths in the moderator. TLDs were arranged between layers of two consecutive depths on 12 radial axes at even intervals so that the monitor is equally sensitive to all directions of neutrons. In order to verify the usefulness of dose evaluation by the monitor, irradiation experiments were conducted at the FRS, JAEA. The D2O-moderated 252Cf was used for the calibration of the monitor. Experiments were also conducted by using two neutron sources of 252Cf bare and 241Am-Be. As a result, the evaluated dose for each irradiation was obtained close to the actual irradiated dose. It was confirmed that the method of dose evaluation by the developed monitor can be applied to practical neutron fields where the distance of neutron source is unknown.

Dopant-pair structures segregated on a hydrogen-terminated Si(100) surface.

Novel atomic structures on a H-terminated Si(100)-(2x1)-H surface were found using scanning tunneling microscopy (STM). The structures are distinguishable only from Si dimers in empty-state STM images. They were observed on arsenic- and phosphorus-doped substrates, but not on boron-doped substrates. Surface density of these structures was found to be proportional to the dopant density in the substrate. First-principles calculations clarify that they are consisting of dopant pairs that are segregated from the bulk material. Hydrogen atoms attached to the dopant pair are found to flip between two positions on the surface due to a quantum effect.

Atomic wire oxidation of H-terminated Si(100)-( 2x1): domino reaction via oxidation and H migration.

We studied oxidation at a dangling bond (DB) on the H-terminated Si(100) surface by the first-principles calculations. We found that oxidation easily occurs at the exposed DB on the H-terminated Si(100) surface. The dissociated O atoms are chemisorbed at a dimer bond and a back bond, resulting in adjacent H atom migration onto the DB. As a consequence of the alternate oxidation and subsequent H atom migration processes, the atomic wire oxidation is actually found to occur on the H-terminated Si(100) surface at low temperatures without desorbing H atoms, as observed in our scanning tunneling microscopy experiment.

Technique for enhanced rare earth separation

A process is demonstrated for the efficient separation of rare earth elements, using a combination of selective reduction and vacuum distillation of halides. The large differences in the redox chemistry of the rare earth elements and in the vapor pressures of rare earth di- and trihalides are exploited for separation. Experimental proof of concept is provided for the binary systems praseodymium-neodymium and neodymium-samarium. This process enhances the separation factor for the isolation of samarium and neodymium from their mixture by more than an order of magnitude.

Atomic and electronic origins of a type- C defect on Si(001)

We present an extensive set of ab initio calculations for a type- C defect on Si(001). Various models belonging to subsurface defects are studied. A substitutional B in the second surface layer is predicted as a possible atomic origin of this defect. However, H and O coupled with second-layer vacancies and a substitutional C are not responsible for a type- C defect. We also discuss how the electronic structure of a type- C defect contributes to its specific scanning tunneling microscopy images.

How and why 41S-2 antibody subunits acquire the ability to catalyze decomposition of the conserved sequence of gp41 of HIV-1.

It has become well known that antibodies obtained by immunization with the ground state of peptides can display proteolytic activity. Our antibody light chain produced by immunization with the peptide RGPDRPEGIEEEGGERDRD, a highly conserved sequence in envelope gp41 of HIV-1 showed the ability to cleave this peptide. Moreover, its heavy chain also decomposed the peptide, although this occurred at lower activity levels compared with the light chain, while the whole antibody did not show any catalytic activity. From molecular modeling, the light and heavy chains of the antibody were deduced to possess catalytic triads (Asp, His, and Ser) in their steric conformations, which may be responsible for the observed proteolytic activity.

Analysis of the antigen recognition sites of anti-methamphetamine monoclonal antibodies (II): unique feature of MA-3 antibody.

A monoclonal antibody against methamphetamine (MA-3 mAb) was found to be strongly bound to ephedrine. This feature was quite different from that of other fourteen mAbs against MA. Analyses of cDNA sequence and steric conformation by molecular modeling revealed that one hydrophilic pocket was generated in the heavy chain of MA-3 mAb involving CDRH-1 and CDRH-2. Asn33, Asn35, Asn50 and Asp52 were the main components of the unique pocket capable of binding to the hydroxyl group of ephedrine.

Removal of catalytic activity by EDTA from antibody light chain.

Gp41 peptide antigen of the HIV-1 envelope (TP41-1:TPRGPDRPEGIEEEGGERDR, a highly conserved region) was enzymatically degraded by the antibody light chain 41S-2-L after an induction period. The peptide bond between Glu14 and Gly15 was cleaved early in the reaction. When EDTA was added in the induction period, it inhibited the degradation of TP41-1 thus ceasing the catalytic activity of 41S-2-L. In contrast, when EDTA was added after the induction period, only a small reduction in the catalytic activity was observed. These observations suggest that metal ions are important in stimulating catalytic activity early in the reaction.

Cloning, sequencing, and characterization of ribosomal protein and RNA polymerase genes from the region analogous to the alpha-operon of escherichia coli in halophilic archaea, halobacterium halobium.

A determination was made of the nucleotide sequence of the 3215-bp region of a ribosomal protein gene cluster (HS13, HS4, HS11, and HeL18), RNA polymerase (RNA poly D), and tRNA genes (tRNAser and tRNAarg) of halophilic Archaea Halobacterium halobium, which is analogous to the alpha-operon of Escherichia coli (tRNAser-HS13-HS4-HS11-RNA poly D-tRNAarg-HeL18). The seven-gene string was preceded by a pseudoknot-like structure similar to the proposed S4 ribosomal protein binding site of the alpha-operon mRNA leader in E. coli. Using an inducible expression system H. halobium HS4 was produced in large amounts in E. coli, and immunoblot analysis showed the S4 to constitute a 21-kDa polypeptide component of the ribosome. Analysis of the deduced amino acids sequence revealed that the HS13, HS4, and HS11 sequences including the RNA polymerase subunit are more similar to their eukaryotic than to their bacterial counterparts. HeL18, located downstream of the gene cluster analogous to the E. coli alpha-operon (S13-S11-S4-RNA poly D-L17), was similar to both the eukaryotic (eL18) and eubacterial ribosomal protein L15 located in the spc-operon, but not to L17 positioned as the terminal gene of the bacterial alpha-operon.

Superoxide dismutase in normal cycling human ovaries: immunohistochemical localization and characterization.

OBJECTIVE: To investigate the expression of manganese (Mn) and copper-zinc (Cu,Zn) superoxide dismutase (SOD) in normal cycling human ovaries throughout the menstrual cycle. DESIGN: Descriptive, controlled study. SETTING: Tohoku University School of Medicine. PATIENT(S): Twenty-four normal cycling human ovaries were obtained from patients who underwent oophorectomy and hysterectomy for squamous cell carcinoma of the uterine cervix. INTERVENTION(S): Immunohistochemistry for Mn-SOD and Cu,Zn-SOD. MAIN OUTCOME MEASURE(S): Immunostaining. RESULT(S): In the follicular stage, Mn-SOD immunoreactivity was detected in granulosa and theca interna cells of steroid-producing follicles, that is, preantral, nondominant, dominant, and atretic follicles, whereas Cu,Zn-SOD was detected in theca interna cells of these follicles and in granulosa cells of dominant follicles. In the luteal stage, immunoreactivity for Mn-SOD and Cu,Zn-SOD was observed in both luteinized granulosa and theca cells of the functioning corpus luteum. In the early degenerating corpus luteum, both Mn-SOD and Cu,Zn-SOD were positive in steroid-producing luteinized theca cells. Mn-SOD immunoreactivity was also detected in nonsteroid-producing luteinized granulosa cells and macrophages. CONCLUSION(S): Our results suggest that the expression of Mn-SOD and Cu,Zn-SOD closely correlates with steroidogenesis in the human ovary. In addition, Mn-SOD may play an important role in the process of luteal regression.

Super catalytic antibody [I]: decomposition of targeted protein by its antibody light chain.

Obtaining an antibody capable of destroying a targeted protein is the eventual goal in developing superior catalytic antibody. We established a monoclonal antibody recognizing a highly conserved sequence, RGPDRPEGIEEEGGERDRD, of gp41 of the HIV-1 envelope. The obtained antibody reacted with gp41 and gp160 of HIV-1. The isolated and purified light chain not only decomposed the above antigenic peptide but also destroyed the gp41 molecule, indicating a novel ability. The decomposition of the antigen is presumably started by scission of the peptide bond between Arg-Gly in the above sequence. The light chain did not decompose BSA and HSA at all, showing the high specificity to antigens. The antibody light chain is referred to as a super catalytic antibody.

Design of novel porphyrin-binding peptides based on antibody CDR.

Novel porphyrin-binding peptides were designed on the basis of an antigen binding site of an antiheme monoclonal antibody. Synthetic peptides were modified with a pyrene moiety. The spectroscopic measurements revealed that the synthetic peptides bound a porphyrin effectively.