Optimal Tailoring of CNT Distribution in Functionally Graded Porous CNTRC Beams.

This paper is concerned with the multi-objective optimization of thickness-wise CNT distribution in functionally graded porous CNT-reinforced composite (FG-porous CNTRC) beams. The mechanical behaviors of FG-porous CNTRC structures are strongly influenced by the thickness-wise distributions of CNTs and porosity. Nevertheless, several linear functions were simply adopted to represent the thickness-wise CNT distribution without considering the porosity distribution, so these assumed linear primitive CNT distribution patterns are not sufficient to respond to arbitrary loading and boundary conditions. In this context, this study presents the multi-objective optimization of thickness-wise CNT distribution in FG-CNTRC porous beams to simultaneously minimize the peak effective stress and the peak deflection. The multi-objective function is defined by the larger value between two normalized quantities and the design variable vector is composed of the layer-wise CNT volume fractions. The constrained multi-objective optimization problem is formulated by making use of the exterior penalty-function method and the aspiration-level adjustment. The proposed optimization method is demonstrated through the numerical experiments, and the optimization solutions are investigated with respect to the porosity distribution and the combination of aspiration levels for two single-objective functions. It is found from the numerical results that the optimum CNT distribution is significantly affected by the porosity distribution. Furthermore, the proposed method can be successfully used to seek an optimum CNT distribution within FG-porous CNTRC structures which simultaneously enhances the multi-objective functions.

Numerical Optimization of CNT Distribution in Functionally Graded CNT-Reinforced Composite Beams.

This paper is concerned with the numerical optimization of the thickness-wise CNT (carbon nanotube) distribution in functionally graded CNT-reinforced composite (FG-CNTRC) beams to secure the structural safety. The FG-CNTRC in which CNTs are inserted according to the specific thickness-wise distribution pattern are extensively investigated for high-performance engineering applications. The mechanical behaviors of FG-CNTRC structures are definitely affected by the distribution pattern of CNTs through the thickness. Hence, the tailoring of suitable CNT distribution pattern is an essential subject in the design of FG-CNTRC structure for a given boundary and loading conditions. Nevertheless, the thickness-wise CNT distribution pattern has been assumed by several linear functions so that these assumed primitive patterns cannot appropriately respond to arbitrary loading and boundary conditions. In this context, this paper aims to introduce a numerical method for optimally tailoring the CNT distribution pattern of FG-CNTRC beams. As a preliminary stage, the effective stress is defined as the objective function and the layer-wise CNT volume fractions are chosen as the design variables. The exterior penalty-function method and golden section method are adopted for the optimization formulation, together with finite difference scheme for the design sensitivity analysis. The proposed optimization method is illustrated and validated through the benchmark experiments, such that it successfully provides an optimum CNT distribution which can significantly minimize the effective stress, with a stable and rapid convergence in the iterative optimization process.

The impact of social media on citation rates in coloproctology.

AIM: This study aimed to investigate the association between Twitter exposure and the number of citations for coloproctology articles. METHOD: Original articles from journals using Twitter between June 2015 and May 2016 were evaluated for the following characteristics: publishing journal; article subject; study design; nationality, speciality and affiliation of the author(s); and reference on Twitter. Citation data for these articles were retrieved from Google Scholar (https://scholar.google.com) in January 2018. We performed a univariate analysis using these data followed by a multivariate, logistic regression analysis to search for factors associated with a high citation level, which was defined as accrual of more than five citations. RESULTS: Out of six coloproctology journals listed on the InCites JCR database, three (Diseases of the Colon & Rectum, Colorectal Disease and Techniques in Coloproctology) used Twitter, where 200 (49.5%) out of a total of 404 articles had been featured. Citation rates of articles that featured on Twitter were significantly higher than those that did not (11.4 ± 9.2 vs 4.1 ± 3.1, P < 0.001). In multivariate analysis, Twitter exposure (OR 8.6, P = 0.001), European Union nationality (OR 2.4, P = 0.004), Colorectal Disease journal (OR 3.3, P = 0.005) and systematic review articles (OR 3.4, P = 0.009) were associated with higher citation levels. CONCLUSION: Article exposure on Twitter was strongly associated with a high citation level. Medical communities should encourage journals as well as physicians to actively utilize social media to expedite the spread of new ideas and ultimately benefit medical society as a whole.

Differential distribution of ganglioside GM3 in seminiferous tubule and epididymis of adult rats.

Gangliosides are ubiquitous membrane components in mammalian cells and are suggested to play important roles in various functions such as cell-cell interaction, adhesion, cell differentiation, growth control and signaling. Among all ganglio-series gangliosides, GM3 has the simplest carbohydrate structure, and has been shown as a major ganglioside in male reproductive system. To study GM3 distribution in the seminiferous tubule and epididymis, frozen sections were stained with specific monoclonal antibody (MAb) against ganglioside GM3. In the seminiferous tubule of testis, pachytene spermatocytes and spermatids expressed ganglioside GM3, but not in spermatogonia and sertoli cells. Spermatogonia and sertoli cells near the basement membrane were negatively reacted to anti-GM3. In the epididymis, GM3 was expressed only in some interstitial cells. Taken together, these results suggest that the expression of ganglioside GM3 in rat seminiferous tubule and epididymis is spatio-temporally regulated during spermatogenesis.

Tumor-specific DNA sequences in human gliomas.

Utilizing the technique of hydroxyapatite chromatography, normal cellular DNAs were used to recycle off the repeat or normal sequences found in [3H]DNA copied off 70S RNA from malignant astrocytomas. The recycled [3H]DNA were then used to hybridize against DNAs from normal human brain tissues and DNAs from malignant astrocytomas or Grade IV astrocytomas. The results indicated the presence of tumor-specific DNA sequences in malignant astrocytomas, absent in normal brain tissues. The percentages were 88% and 7%, respectively. When recycled medulloblastoma 70S[3H]DNA probes were utilized against DNA'S FROM Grade IV astrocytomas and from normal brain, similar results were obtained. The respective percentages of hybridization were 67% and 7%. Thus it would appear that malignant gliomas contain tumor-specific DNA sequences which are not found in normal brain tissues.

Biochemical evidences for ribonucleic acid viral-like characteristics in malignant diseases of gastrointestinal tract and lung in humans.

It has been demonstrated that malignant diseases of the gastrointestinal tract and lung in humans possess three characteristics invariably found in ribonucleic acid tumor viruses: the presence of a ribonucleic acid directed deoxyribonucleic acid polymerase, reverse transcriptase; a high molecular weight ribonucleic acid with a sedimentation coefficient of 70 Svedberg units, and particulate elements with densities of 1.16 to 1.18 grams per milliliter sucrose gradient. Twelve of 17 carcinomas of the colon, three of five carcinomas of the stomach, all three carcinomas of the rectum and seven of ten carcinomas of the lung displayed detectable evidence of these viral-like entities. None of the corresponding normal tissues had positive reactions.

Molecular evidence for a viral etiology of human CNS tumors.

The newer methods of molecular virology, including molecular hybridization and the "simultaneous detection test," were used to examine human brain tumors for evidence of RNA tumor viruses. It was found that they contained 70S RNA and RNA-directed DNA polymerase, both encapsulated in a particle possessing a density of 1.17 g/ml. These particles therefore satisfy the three diagnostic features that characterize the animal RNA tumor viruses. Of 26 of the most malignant (glioblastoma and medullo blastoma) brain tumors examined, 24 (92%) contained these virus-like entities. The possible usefulness of these particles as aids in diagnosis and monitoring therapy is briefly discussed.

Oncornavirus-like particles in human skin cancers.

A high-molecular-weight RNA encapsulated with an RNA-instructed DNA polymerase in particles possessing the density characteristic of the RNA tumor viruses has been detected in 13 out of 14 human malignant melanomas. The [3H]DNA synthesized by these particles in an endogenous reaction hybridizes to RNA extracted from the human melanoma particulate structures, but not to RNA from normal skin. Similar particles containing RNA and enzyme have been found in basal cell and squamous cell carcinomas of the skin. The RNA of the melanoma particles is easily distinguishable by hybridization from the RNAs found in the particles of the basal and squamous cell carcinomas.

Evidence of particle-associated RNA-directed DNA polymerase and high molecular weight RNA in human gastrointestinal and lung malignancies.

Previous communications have demonstrated that neoplastic cells of human breast cancers, leukemias, lymphomas, sarcomas, and brain tumors contain particles with similar diagnostic attributes as those found in RNA oncornaviruses. The present paper concerns malignancies of the gastrointestinal and pulmonary systems for which, like brain tumors, no suitable animal model or corresponding virus exists. By means of the simultaneous detection assay, these tumors have been found to contain 70S RNA and RNA-directed DNA polymerase encapsulated in particulate components possessing densities of 1.16-1.17 g/ml. Twelve out of 17 (70%) colon carcinomas, three out of five (60%) gastric carcinomas, all of three rectal carcinomas, and seven out of ten (70%) lung carcinomas contained detectable levels of these virus-like entities. None of the corresponding normal tissues was positive.

The presence of unique DNA sequences after viral induction of leukemia in mice. (RNA tumor virus-nucleic acid hybridization-insertion of viral DNA).

From previous studies, lymphocyte DNA from human leukemias and DNA from involved tissues of patients with Hodgkin's disease or Burkitt's lymphoma contain sequences that are absent from their normal counterparts. These sequences are related to those found in particulate elements associated with these neoplasias and possessing biochemical properties characteristic of RNA tumor viruses. Similar observations have been made of unique sequences related to those of the feline virus RD-114 and found in spontaneous mastocytomas in cats. Here we extend these results to the classical murine model of virus-induced leukemias. Splenic DNA from BALB/c mice with leukemia induced by Rauscher leukemia virus (RLV) possess some RLV-related sequences that do not exist in normal BALB/c DNA. Furthermore, these leukemia-specific sequences were absent in all other mouse strains examined, including AKR, a strain with a high incidence of spontaneous leukemia. The DNA of all noninfected mouse strains possesses considerable homology with the RLV genome. Temperature denaturation studies indicate, however, that although the RLV-related sequences found in all normal mice are similar to each other, they are not exactly homologous with RLV sequences. We conclude that RLV-induced leukemia in BALB/c results in the insertion of RLV sequences into cellular DNA that itself possesses only partial homology with the RLV genome.

Particles with RNA of high molecular weight and RNA-directed DNA polymerase in human brain tumors.

We have previously shown that neoplastic cells of human breast cancers, leukemias, lymphomas, and sarcomas contain particles similar to the viruses that have been established as etiologic agents of these diseases in mice. The present paper concerns tumors of the central nervous system for which no suitable animal model or corresponding virus exists. Nevertheless, using the simultaneous detection test, we showed that human brain tumors contain 70S RNA and RNA-directed DNA polymerase encapsulated in a particulate component possessing a density of 1.17 g/ml. These particles satisfy the three diagnostic criteria that characterize RNA tumor viruses of animals. 24 Out of 26 (92%) of the most malignant (glioblastoma and medulloblastoma) brain tumors examined contained these virus-like entities.