[Analysis of disease composition and primary surgical procedures in pediatric secondary glaucoma inpatients: a single-center study]

Objective: To analyze the disease composition and primary surgical procedures in pediatric inpatients with secondary glaucoma. Methods: A retrospective case series study was conducted. Clinical data of children aged≤16 years with secondary glaucoma who were admitted to the Zhongshan Ophthalmic Center, Sun Yat-sen University, between January 1, 2017, and December 31, 2021, were included. The patients were classified according to the Childhood Glaucoma Research Network (CGRN) classification system, and their diagnoses, underlying factors, gender, age of onset, affected eye(s), age and type of initial surgery, and ophthalmic examination data were analyzed. Statistical analysis was performed using Kruskal-Wallis rank sum test and χ2 test. Results: A total of 540 patients (744 eyes) were included in this study, comprising 319 males (59.1%) and 221 females (40.9%). Unilateral disease was observed in 336 cases (62.2%), while bilateral involvement was present in 204 cases (37.8%). The age of onset was 4.0 (0.0, 9.0) years, and the median age of the first anti-glaucoma surgery was 5.0 (0.7, 10.0) years. Among them, there were 195 cases (36.1%) of secondary glaucoma associated with non-acquired ocular anomalies (SCG-O), with a median age of onset of 0.0 (0.0, 4.0) years, and 97 of these cases (49.7%) were male. secondary glaucoma associated with non-acquired systemic disease or syndrome (SCG-S) were observed in 68 cases (12.6%), with a median age of glaucoma onset of 0.1 (0.0, 4.0) years, and 47 of these cases (69.1%) were male. Secondary glaucoma associated with acquired conditions (SCG-A) accounted for 192 cases (35.6%), with a median age of onset of 9.0 (5.0, 13.0) years, and 125 of these cases (65.1%) were male. There were 85 cases (15.7%) of secondary glaucoma following cataract surgery (SCG-C), with a median age of onset of 3.0 (0.8, 7.0) years, and 50 of these cases (58.8%) were male. Male patients were predominant in SCG-S and SCG-A, with 47 cases (69.1%) and 125 cases (65.1%), respectively (χ2=9.94, 17.52; P=0.002,<0.001). Except for SCG-O, all other types of pediatric secondary glaucoma predominantly affected only one eye: SCG-S in 52 cases (76.5%), SCG-A in 128 cases (66.7%), and SCG-C in 54 cases (63.5%) (χ2=19.06, 21.33, 6.22; all P<0.05). The highest proportion of SCG-O was attributed to congenital ectropion uveae (46 cases, 23.6%). Sturge-Weber syndrome was the most common SCG-S (45 cases, 66.3%), while SCG-A mostly resulted from trauma (59 cases, 30.8%) and corticosteroid use (56 cases, 29.2%). Trabeculectomy (211 eyes, 30.8%) and glaucoma drainage device implantation (197 eyes, 28.7%) were the most frequently performed primary surgical procedures. Conclusions: SCG-O and SCG-A were found to be common types of pediatric secondary glaucoma. The age of onset and the choice of primary anti-glaucoma surgical procedures varied among different types of pediatric secondary glaucoma. However, overall, trabeculectomy and glaucoma drainage device implantation were the primary surgical procedures predominantly employed.

[Research progress on the epidemiology and risk factors of dry eye in children]

The prevalence of dry eye in children is increasing with changes in the environment and the widespread use of electronic products. However, due to poor ability to express themselves and hidden symptoms of children, lack of understanding of dry eye in children, children with dry eye are likely to be misdiagnosed. Dry eye can seriously affect the quality of children's learning, life, vision and visual development. Therefore, it is urgent to raise awareness of clinical workers about dry eye in children, prevent the occurrence of related complications of dry eye, and avoid permanent visual damage to children. This review discusses and summarizes the epidemiology and common risk factors of children with dry eye, with the aim of improving doctors' understanding of dry eye in children.

[Impact of exposure to ambient fine particulate matter-bound polycyclic aromatic hydrocarbons on blood thrombogenicity in adults]

Objective: To investigate the effects of exposure to ambient fine particulate matter-bound polycyclic aromatic hydrocarbons on blood coagulation in adults. Methods: A total of 73 adult volunteers were recruited in a cohort study and had four clinical visits from November 2014 to January 2016. Blood samples were obtained and used to measure biomarkers of blood thrombogenicity, including soluble CD40 Ligand (sCD40L), soluble P-selection (sCD62P) and Fibrinogen (FIB). White blood cell (WBC), 8-Hydroxy-2'-Deoxyguanosine (8-OHdG), matrix metalloproteinase-2 (MMP-2) and HDL cholesterol efflux capacity (HDL-CEC) were also determined. Daily concentrations of ambient fine particulate matter-bound polycyclic aromatic hydrocarbons (PAHs) were measured throughout the study period, and positive matrix factorization (PMF) approach was used to identity PAHs sources. Linear mixed-effect models including single-pollutant model, two-pollutant model and stratification analysis were constructed to estimate the effects of exposure to ambient fine particulate matter-bound PAHs on blood thrombogenicity in adults after adjusting for potential confounders. Results: The mean age of participants was (23.3±5.4) years. During the study period, the median level of PM_2.5-bound PAHs was (55.29±74.99) ng/m³. Six sources of PM_2.5-bound PAHs were identified by PMF, with traffic sources contributing more than 50%. The linear mixed-effect model showed that PAHs exposure had a significant effect on elevated blood thrombogenicity. Significant elevations in sCD40L, sCD62P and FIB associated with per IQR increase (60.33 ng/m³) in exposure to PAHs were 14.36% (95%CI:6.94%-22.28%), 9.33% (95%CI: 1.71%-17.51%) and 2.07% (95%CI:0.44%-2.07%) at prior 5 days, respectively. Blood thrombogenicity levels were significantly and positively correlated with source-specific PAHs, especially gasoline vehicle emissions, diesel vehicle emission and coal burning at prior 1 or 5 days. Stronger associations between PAHs and increased blood thrombogenicity were found in participants with high plaque vulnerability, reduced HDL function, and high levels of inflammation and oxidative stress. Conclusion: Acute exposure to ambient fine particulate matter-bound PAHs, especially PAHs from traffic sources may promote blood thrombogenicity in adults, and PAHs have stronger effects on participants with reduced vascular function and high levels of inflammation and oxidative stress.

[Research advances in the pathogenesis of exfoliative glaucoma]

Exfoliative glaucoma is a type of glaucoma secondary to pseudoexfoliation syndrome. In recent years, great progress has been made in the research of pathogenesis and risk factors of exfoliative glaucoma. A variety of risk genes, abnormal growth factors and cytokines, changes in the anterior and posterior segments have been found. Based on the systematic summary of these achievements, this article points out the problems that need to be further studied, so as to provide a reference for future research in this field.

[Efficacy of multisensory training and rehabilitation in patients with balance disorders]

Objective: To analyze the clinical efficacy of multisensory training and rehabilitation treatment in patients with balance disorders. Methods: From January to December 2020, 95 patients with balance disorders in the Vertigo Center of Department of Otorhinolaryngology, Union Hospital Affiliated to Tongji Medical College, Huazhong University of Science and Technology were enrolled. All patients were treated according to the treatment guidelines of Chinese Medical Association or expert consensus. Those with poor recovery or unsatisfactory treatment results underwent multisensory training and rehabilitation for 1 month after a comprehensive evaluation. The scores of Visual Analogue Scale (VAS), Dizziness Handicap Inventory (DHI), Berg Balance Scale (BBS), and Activities-specific Balance Confidence Scale (ABC), Somatization Symptom Self-Rating Scale (SSS), 9-item Patient Health Questionnaire (PHQ9) and the 7-item Generalized Anxiety Disorder (GAD7) were evaluated and compared before and after the treatment. Results: Totally, 95 patients were enrolled. There were 34 males and 61 females, aged (44±14) years. VAS (2.1±1.1 vs 5.9±2.5, P<0.01), DHI (15.6±7.7 vs 33.1±13.2, P<0.01), SSS (1.5±0.6 vs 2.4±0.8, P<0.01), PHQ9 (6.0±2.7 vs 8.6±4.3, P=0.01) and GAD7 (5.2±2.6 vs 9.5±2.8, P<0.01) decreased after treatment, while BBS (53.4±10.0 vs 34.8±10.7, P<0.01) and ABC (89.6±8.0 vs 55.7±21.8, P<0.01) increased. Conclusion: Multisensory training and rehabilitation therapy can effectively enhance the vertigo control rate and balance ability in patients with balance disorders, reduce the risk of falling, promote their mental and psychological state, and thus improve the quality of life.

[Short-term outcomes of modified load-sharing rip-stop repair compared with suture-bridge repair for large rotator cuff tears]

Objective: To examine the short-term outcomes of modified load-sharing rip-stop repair (mLSRS) and suture-bridge repair (SB) for large rotator cuff tear. Methods: The clinical data of patients who underwent shoulder arthroscopy for large rotator cuff repair at Department of Orthopedic, China Academy of Chinese Medical Sciences Wang Jing Hospital from January 2017 to December 2018 were collected. Totally 111 patients (39 in mLSRS group and 72 in SB group) were included in the study. There were 45 males and 66 females, aged (58.0±6.9)years (range: 40 to 72 years).A total of 39 pairs of patients were successfully matched by propensity score matching. The pain of shoulder joint was assessed by visual analogy score (VAS) , the shoulder function was assessed by Constant-Murley score, the abduction strength of bilateral shoulder joint was assessed by 90˚ force assessment method of upper limb on the plane of scapula, and the healing of rotator cuff on the operative side was assessed by sugaya ultrasonic classification standard. The difference of short-term outcome between the two groups were compared using t test, χ(2) test, Mann-Whitney U test, repeated measures design anova and multivariate analysis of variance. Results: At the 4th week after surgery, the VAS of mLSRS group was significantly lower than SB group(1 (2) vs. 2 (2) , F=5.32, P=0.02). One year after surgery, Constant-Murley score of two groups were significantly higher than those before surgery, but there was no significant difference between two groups(89.1±5.7 vs. 87.6±7.3, t=1.00, P=0.32). Abductor strength of affected limbs were lower than that of the opposite side, but there were no statistically significant differences between two groups(4.28±1.61 vs. 4.54±1.64, t=-0.70, P=0.49). According to the Sugaya classification, 32 cases in mLSRS group were healed while 7 cases were not healed,30 cases in SB group were healed while 9 cases were not healed(χ(2)=0.32, P=0.58). Conclusion: The use of mLSRS fixation construct on large rotator cuff tear can reduce pain and the short-term outcome is reliable.

[Mechanism of microglia promoting retinal ganglion cell death in vitro]

Objective: To investigate the role and mechanism of microglial activation in the process of retinal ganglion cell (RGC) death in the oxygen-glucose deprivation/reperfusion (OGD/R) model which mimicked retinal ischemia/reperfusion injury in vitro. Methods: Experimental study. Primary RGCs from C57BL/6 mice and BV2 microglia were co-cultured or cultured alone. The OGD/R model was established in vitro (reoxygenation time was set to 6 h, 24 h, 36 h, 48 h). BV2 microglial activation was assessed by immunofluorescence staining of ionized calcium binding adapter molecule 1 (iba1), and the survival rate of RGCs was detected by the Cell Counting Kit-8. The apoptosis rate of RGC was detected by using apoptosis detection kit. The levels of Toll-like receptor-4 (TLR4) and Nod-like receptor family pyrin domain containing protein 3 (NLRP3) in BV2 cells were detected by PCR, Western-blot and immunofluorescence staining. The activity of caspase-8 in BV2 cells was detected by the CaspGLOW Kit, and the content of interleukine-1β (IL-1β) in the supernatant was detected by enzyme linked immunosorbent assay. After the corresponding pathways were blocked by TLR4 small interfering RNA (siRNA) transfection or caspase-8 inhibitor, the expression changes of TLR4 and NLRP3, the activity of caspase-8, and the difference of IL-1β content could be observed as well as the activity of RGCs co-cultured with BV2. Statistical analysis was performed using analysis of variance. Results: Under co-culture of RGC and BV2 cells, cellular immunofluorescence detection showed that the expression of iba1 in BV2 cells increased, which indicated BV2 cells were activated significantly in the OGD/R model. In the OGD/R model, the apoptosis rate of RGC co-cultured with BV2 cells (71.1%±3.2%) was significantly higher than that of RGC cultured alone (35.1%±1.8%) (t=10.10, P<0.01). Cellular immunofluorescence detection showed that the expression of TLR4 and NLRP3 in BV2 cells in the OGD/R model increased significantly when BV2 cells were cultured alone, and their mRNA levels increased significantly with prolongation of reoxygenation time (F=64.45, 72.74; P<0.01), and peaked at OGD/R 24 h (TLR4 mRNA, relative ratio to control was 2.83±0.23; NLRP3 mRNA, relative ratio to control was 3.12±0.27). Caspase-8 activity also increased with prolonged reoxygenation time, the difference was statistically significant (F=93.57, P<0.01), and peaked at OGD/R 24 h (relative ratio to control was 2.92±0.31). After transfection of BV2 cells with TLR4 siRNA, its caspase-8 activity was significantly inhibited, but using caspase-8 inhibitor did not affect the up-regulation of TLR4 expression in BV2 cells. However, the mature IL-1β secreted by BV2 cells exposed to OGD/R was significantly reduced by using caspase-8 inhibitor (from 3.52±0.55 to 1.39±0.37, t=7.19, P<0.01), meanwhile, the expression of NLRP3 was also significantly decreased after caspase-8 inhibitor pretreatment (from 2.79±0.23 to 1.37±0.19, t=9.37, P<0.01). In the OGD/R model, the activity of RGC cells co-cultured with TLR4 siRNA-transfected BV2 cells was 74.5%±1.2%, and the activity of RGC cells co-cultured with BV2 cells treated with caspase-8 inhibitor was 62.8%±1.5%, those were both higher than that of RGC cells co-cultured with untreated BV2 cells (36.7%±0.3%), and the difference was statistically significant (t=11.60, 6.83; both P<0.01). Conclusion: TLR4-caspase-8-NLRP3 inflammasome pathway is activated in microglia exposed to OGD/R, resulting in the production of IL-1β, thereby contributing to the death of RGCs. (Chin J Ophthalmol, 2020, 56: 32-40).

[Effects and mechanism of lncRNA serving as ceRNA in non-obstructive azoospermia]

Objective: To investigate the mechanisms of lncRNA on the occurrence and development of NOA by constructing ceRNA regulation network of lncRNA, miRNA and mRNA. Methods: Samples of adult human testis were obtained from NOA patients and OA patients with normal spermatogenesis (controls), recruited from the Reproductive Medicine Center of Nanfang Hospital from June 2017 to June 2018. Differentially expressed lncRNAs and mRNAs in testicular tissues from patients with NOA were identified by microarray analysis in previous association study. In this study, differentially expressed lncRNAs and mRNA were used to construct the ceRNA regulatory network in NOA and clarify the interaction relationship among lncRNA, miRNA and mRNA. GeneMANIA database was used to construct Protein-Protein Interaction (PPI) of the mRNAs in ceRNA regulatory network. WebGestalt toolkit was employed to perform gene function and pathway enrichment analyses of those coding genes. Finally, qRT-PCR and dual luciferase reporter system were employed for further experimental validation. Results: The ceRNA regulatory network of lncRNA, miRNA and mRNA consists of 21 nodes and 26 edges, of which 4 lncRNAs, 13 miRNAs and 4 mRNAs. 19 proteins were found to interact with the mRNA coding proteins in ceRNA regulatory network by PPI analysis. Gene oncology and KEGG pathway enrichment analyses indicate these coding genes were significantly enriched in pentose metabolic process and pentose phosphate pathway. Furthermore, lncRNA ANXA2P3 was found binding with miR-613 and miR-206 to inhibit mRNA TKT expression. Conclusion: lncRNAs exert an important role in the occurrence and development of NOA via ceRNA regulatory network, which could be used as new biomarkers for NOA treatment.

[Modification factors associated with maternally inherited non-syndromic hearing loss]

Mutations in the mitochondrial DNA have been certified to be one of the most important causes of maternally inherited sensorineural hearing loss. Among these, mitochondrial 12S rRNA1555A>G, 1494C>T and other mutations are associated with both nonsyndromic and drug induced hearing loss caused by aminoglycosides. Individuals carrying 1555A>G or 1494C>T mutation have a variety of clinical manifestations, which implies that the 1555A>G or 1494C>T mutation is a chief factor underlying the development of deafness but insufficient to produce the clinical phenotype. Therefore other modifier factors, such as aminoglycosides, mitochondrial haplotypes, secondary mutation or nuclear modifier genes, may play an important role in the phenotypic expression of the deafness-associated mitochondrial 12S rRNA1555A>G or 1494C>T mutation. In this review, the modifier factors for the phenotypic expression of deafness-associated mitochondrial 12S rRNA1555A>G or 1494C>T mutations were summarized and proposed the pathogenesis of maternally inherited deafness.

Interleukin-6 gene -174G>C polymorphism and chronic obstructive pulmonary disease risk: a meta-analysis

Association studies of interleukin-6 (IL-6) -174G>C polymorphism and chronic obstructive pulmonary disease (COPD) have yielded inconsistent results, possibly because single studies often lack sufficient statistical power. A comprehensive search was performed in the PubMed, Embase, Elsevier, Web of Science databases, Wanfang, and the Chinese National Knowledge Infrastructure (CNKI) databases for published studies investigating the associations between IL-6 -174G>C polymorphism and COPD. Odds ratios (OR) and 95% confidence intervals (95%CI) were used to assess the possible associations. Seven studies with a total of 2701 subjects were included in this meta-analysis. A significantly increased risk was detected in the C allele of the IL-6 -174G>C in Caucasians (C vs G: OR = 1.16, 95%CI = 1.03-1.30; CC+GC vs GG: OR = 1.21, 95%CI = 1.02-1.42; CC vs GG: OR = 1.32, 95%CI = 1.03-1.70). This meta-analysis suggests that the C allele of the IL-6 -174G>C might act as a COPD risk factor in Caucasians. Further well-designed case-control studies with larger sample sizes are needed to confirm these conclusions.

Development of 18 microsatellite loci for the freshwater snail Bellamya aeruginosa (Mollusca, Gastropoda)

Although it is a major freshwater gastropod species, genetic diversity of Bellamya aeruginosa was completely unknown. Eighteen microsatellite loci were isolated and characterized from (AC)(15)-enriched genomic libraries of the freshwater snail B. aeruginosa. Most of the 18 loci were successfully amplified and high polymorphic information content values were found, ranging from 0.244 to 0.792 (mean 0.541). The number of alleles per locus ranged from 5 to 13 (mean 8.8), the expected heterozygosity varied from 0.347 to 0.950 (mean 0.815) and the observed heterozygosity varied from 0.087 to 0.782 (mean 0.431). Eight loci showed significant deviation from Hardy-Weinberg equilibrium after Bonferroni's correction and no significant genotypic linkage disequilibrium was detected between most locus pairs, except for TXH79-TXH97 and TXH113-TXH121. These 18 polymorphic microsatellite loci should be useful for population genetics analysis and species identification of Bellamya.

Aligned carbon nanotubes sandwiched in epitaxial NbC film for enhanced superconductivity

Highly aligned carbon nanotube (CNT) ribbons were sandwiched in epitaxial superconducting NbC films by a chemical solution deposition method. The incorporation of aligned long CNTs into NbC film enhances the normal-state conductivity and improves the superconducting properties of the assembly.

Lipopolysaccharide-induced dental pulp cell apoptosis and the expression of Bax and Bcl-2 in vitro

Lipopolysaccharide exerts many effects on many cell lines, including cytokine secretion, and cell apoptosis and necrosis. We investigated the in vitro effects of lipopolysaccharide on apoptosis of cultured human dental pulp cells and the expression of Bcl-2 and Bax. Dental pulp cells showed morphologies typical of apoptosis after exposure to lipopolysaccharide. Flow cytometry showed that the rate of apoptosis of human dental pulp cells increased with increasing lipopolysaccharide concentration. Compared with controls, lipopolysaccharide promoted pulp cell apoptosis (P < 0.05) from 0.1 to 100 μg/mL but not at 0.01 μg/mL. Cell apoptosis was statistically higher after exposure to lipopolysaccharide for 3 days compared with 1 day, but no difference was observed between 3 and 5 days. Immunohistochemistry showed that expression of Bax and Bcl-2 was enhanced by lipopolysaccharide at high concentrations, but no evident expression was observed at low concentrations (0.01 and 0.1 μg/mL) or in the control groups. In conclusion, lipopolysaccharide induced dental pulp cell apoptosis in a dose-dependent manner, but apoptosis did not increase with treatment duration. The expression of the apoptosis regulatory proteins Bax and Bcl-2 was also up-regulated in pulp cells after exposure to a high concentration of lipopolysaccharide.

Scale and twist effects on the strength of nanostructured yarns and reinforced composites

In this work we investigate the effects of yarn diameter and gauge length on the statistical strength of yarns spun from carbon nanotubes (CNTs). Tensile tests are conducted on a large sample set of nanostructured CNT yarns. The data show that strength varies substantially and both strength and statistical dispersion in strength decreases as yarn diameter increases. To explain these phenomena and forecast their effects on larger-scale structures, a hierarchical set of Monte Carlo simulation models is developed: the lower-scale model aims to predict the relationship between yarn nanostructure and tensile strength and the higher-scale model aims to relate the strength of CNT yarns to the strength of composites reinforced with unidirectionally aligned CNT yarns. Predictions indicate that, for both structures, the mean and statistical variation in strength will decrease as the surface twist angle, number of CNTs in cross section and gauge length of the yarn increases. The predicted reductions in variability due to yarn nanostructure will be important for determining ways to minimize the detrimental effects of increasing length scale on strength.

Strong strain hardening in nanocrystalline nickel

Low strain hardening has hitherto been considered an intrinsic behavior for most nanocrystalline (NC) metals, due to their perceived inability to accumulate dislocations. In this Letter, we show strong strain hardening in NC nickel with a grain size of approximately 20 nm under large plastic strains. Contrary to common belief, we have observed significant dislocation accumulation in the grain interior. This is enabled primarily by Lomer-Cottrell locks, which pin the lock-forming dislocations and obstruct dislocation motion. These observations may help with developing strong and ductile NC metals and alloys.

Strong and ductile colossal carbon tubes with walls of rectangular macropores

We report a new type of carbon material-porous colossal carbon tubes. Compared with carbon nanotubes, colossal carbon tubes have a much bigger size, with a diameter of between 40 and 100 mum and a length in the range of centimeters. Significantly, the walls of the colossal tubes are composed of macroscopic rectangular columnar pores and exhibit an ultralow density comparable to that of carbon nanofoams. The porous walls of colossal tubes also show a highly ordered lamellar structure similar to that of graphite. Furthermore, colossal tubes possess excellent mechanical and electrical properties.

Inverse grain-size effect on twinning in nanocrystalline Ni

A long-standing controversy exists between molecular dynamics simulations and experiments on the twinning propensity of nanocrystalline (NC) face-centered-cubic metals. For example, three-dimensional molecular dynamics simulations rarely observed twins in NC Ni, whereas experiments readily observed them. Here this discrepancy is resolved by experimental observation of an inverse grain-size effect on twinning. Specifically, decreasing the grain size first promotes twinning in NC Ni and then hinders twinning due to the inverse grain-size effect. Interestingly, no inverse grain-size effect exists on stacking fault formation. These observations are explained by generalized planar fault energies and grain-size effect on partial emissions.

New deformation twinning mechanism generates zero macroscopic strain in nanocrystalline metals

Macroscopic strain was hitherto considered a necessary corollary of deformation twinning in coarse-grained metals. Recently, twinning has been found to be a preeminent deformation mechanism in nanocrystalline face-centered-cubic (fcc) metals with medium-to-high stacking fault energies. Here we report a surprising discovery that the vast majority of deformation twins in nanocrystalline Al, Ni, and Cu, contrary to popular belief, yield zero net macroscopic strain. We propose a new twinning mechanism, random activation of partials, to explain this unusual phenomenon. The random activation of partials mechanism appears to be the most plausible mechanism and may be unique to nanocrystalline fcc metals with implications for their deformation behavior and mechanical properties.

Drying induced upright sliding and reorganization of carbon nanotube arrays

Driven by capillary force, wet carbon nanotube (CNT) arrays have been found to reorganize into cellular structures upon drying. During the reorganization process, individual CNTs are firmly attached to the substrate and have to lie down on the substrate at cell bottoms, forming closed cells. Here we demonstrate that by modifying catalyst structures, the adhesion of CNTs to the substrate can be weakened. Upon drying such CNT arrays, CNTs may slide away from their original sites on the surface and self-assemble into cellular patterns with bottoms open. It is also found that the sliding distance of CNTs increases with array height, and drying millimetre tall arrays leads to the sliding of CNTs over a few hundred micrometres and the eventual self-assembly into discrete islands. By introducing regular vacancies in CNT arrays, CNTs may be manipulated into different patterns.

Compact and dissociated dislocations in aluminum: implications for deformation

Atomistic simulations, confirmed by electron microscopy, show that dislocations in aluminum can have compact or dissociated cores. The calculated minimum stress (sigma(P)) required to move an edge dislocation is approximately 20 times smaller for dissociated than for equivalent compact dislocations. This contradicts the well accepted generalized stacking fault energy paradigm that predicts similar sigma(P) values for both configurations. Additionally, Frank's rule and the Schmid law are also violated because dislocation core energies become important. These results may help settle a 50-year-old puzzle regarding the magnitude of sigma(P) in face-centered-cubic metals, and provide new insights into the deformation of ultra-fine-grained metals.

Ultralong single-wall carbon nanotubes

Since the discovery of carbon nanotubes in 1991 by Iijima, there has been great interest in creating long, continuous nanotubes for applications where their properties coupled with extended lengths will enable new technology developments. For example, ultralong nanotubes can be spun into fibres that are more than an order of magnitude stronger than any current structural material, allowing revolutionary advances in lightweight, high-strength applications. Long metallic nanotubes will enable new types of micro-electromechanical systems such as micro-electric motors, and can also act as a nanoconducting cable for wiring micro-electronic devices. Here we report the synthesis of 4-cm-long individual single-wall carbon nanotubes (SWNTs) at a high growth rate of 11 microm s(-1) by catalytic chemical vapour deposition. Our results suggest the possibility of growing SWNTs continuously without any apparent length limitation.

Formation of pile networks by long carbon nanotubes from decomposition of CO on Co-Mo film

We report the formation of pile networks by long carbon nanotubes grown at 700 degrees C from a Co-Mo film on a quartz plate. Carbon monoxide (CO) was used as the carbon source. The networks were formed because the density of catalyst particles on the substrate was low, which resulted in low carbon nanotube density that did not support vertical growth. At the same time, the low carbon nanotube density makes it possible for CO to reach the catalysts on the substrate for continuous growth. No obvious amorphous carbon chunks were observed, suggesting that the pile networks consisted of fairly high-quality, long carbon nanotubes.

Microstructures and properties of ultrafine-grained pure titanium processed by equal-channel angular pressing and cold deformation

Equal-channel angular pressing (ECAP) has been used to refine the grain size of commercially pure (CP) titanium as well as other metals and alloys. CP-Ti is usually processed at about 400 degrees C because it lacks sufficient ductility at lower temperature. The warm processing temperature limits the ability of the ECAP technique to improve the strength of CP-Ti. We have employed cold deformation following warm ECAP to further improve the strength of CP-Ti. Ti billets were first processed for eight passes via ECAP route Bc, with a clockwise rotation of 90 degrees between adjacent passes. The grain size obtained by ECAP alone is about 260 nm. The billets were further processed by cold deformation (cold rolling) to increase the crystalline defects such as dislocations. The strength of pure Ti was improved from 380 to around 1000 MPa by the two-step process. This article reports the microstructures, microhardness, tensile properties, and thermal stability of these Ti billets processed by a combination of ECAP and cold deformation.

Studies on mechanism of action of luteinizing releasing hormone (LH-RH) in ovulation of fish--intracellular distribution of LH-RH-A in pituitary gonadotrophs as revealed by electron-microscopic autoradiography

The results of competitive bending experiment and the electron-microscopic autoradiographic studies show that the peptide hormone, LH-RH-A (a nonapeptide), could be internalized into the gonadotrophs of the pituitary gland of the mud-carp (Cirrhrinus molitorella). It is demonstrated that the labeled peptide, 125I-LH-RH-A, is internalized not only into the cytoplasm, but also into the nucleus, apparently via the nuclear pores. It is, therefore, suggested that the peptide hormone might act directly on the genome either in the form of a hormone-receptor complex or of a single molecule.