Web Formation Research Articles

The Influence of Basalt Fiber Orientation on the Mechanical Property of Composite Board

The composite board was made of chopped basalt and polypropylene fibers. The manufacturing process included blending, carding, web formation, laminating and compression molding. The tension and bending properties were investigated experimentally. The load - displacement curve of the tensile test revealed that the elastic modulus and maximum vertical load in the longitudinal were far greater than these in the transverse direction; and tensile strengths were far apart in the longitudinal and transverse direction as well. In comparison with the tensile tests, the effect of basalt fiber orientation on the bending modulus and strength were relatively insignificant. In addition, from the micro fibril angle, we also verify that the orientation angle of basalt fiber is an important factor of influence to the mechanical property. In the similar study, the influence hadn’t been seen sufficiently, so this paper provides reference to the actual application of the composite board.

The formation of terrestrial food webs in glacier foreland: Evidence for the pivotal role of decomposer prey and intraguild predation

We investigated the structure of invertebrate food webs at three glacier foreland sites of an age of 2–34, ca. 60 and ca. 120 years in the European Alps at 2250–2450 m asl. The trophic structure was investigated by analyzing stable isotope ratios of 15 N/ 14 N and 13 C/ 12 C. The results suggest that the formation of terrestrial food webs during early primary succession heavily relies on prey out of the decomposer system with Collembola being most important. The diet of decomposers likely is based predominantly on allochthonous humus material blown in by wind and deposited by the retreating glacier. Irrespective of the successional stage the animal community consisted mainly of generalist predators with a number of species occurring at each of the successional stages. The results suggest that terrestrial food web formation is associated with a prolongation of food chains caused mainly by predator species switching their diet to include other predators, i.e. by intraguild predation. This suggests that generalist predators, such as cursorial spiders, carabid beetles, harvestman and centipedes, switch prey and include other predators if these are becoming more abundant, i.e. if ecosystems become more productive. Intraguild predation results in complex food webs with high linkage density which likely affects food web functioning and stability.

Amphipathic α-Helix AH2 Is a Major Determinant for the Oligomerization of Hepatitis C Virus Nonstructural Protein 4B

Nonstructural protein 4B (NS4B) is a key organizer of hepatitis C virus (HCV) replication complex formation. It induces a specific membrane rearrangement, designated membranous web, that serves as a scaffold for the HCV replication complex. However, the mechanisms underlying membranous web formation are poorly understood. Based on fluorescence resonance energy transfer (FRET) and confirmatory coimmunoprecipitation analyses, we provide evidence for an oligomerization of NS4B in the membrane environment of intact cells. Several conserved determinants were found to be involved in NS4B oligomerization, through homotypic and heterotypic interactions. N-terminal amphipathic α-helix AH2, comprising amino acids 42 to 66, was identified as a major determinant for NS4B oligomerization. Mutations that affected the oligomerization of NS4B disrupted membranous web formation and HCV RNA replication, implying that oligomerization of NS4B is required for the creation of a functional replication complex. These findings enhance our understanding of the functional architecture of the HCV replication complex and may provide new angles for therapeutic intervention. At the same time, they expand the list of positive-strand RNA virus replicase components acting as oligomers.

The Research on the Mechanical Property of CBF/PP Composite Board

The three composite boards which were made of continuous basalt fiber (CBF) and polypropylene fiber (PP) in different fiber ratios were researched on this paper. The manufacturing forming process included blending, carding, web formation, laminating and compression molding orderly. The tension and bending properties were investigated experimentally, and then dual variance analysis was used to show the significant difference of the mechanical property in the transverse and longitudinal orientation as well the appreciable impact of different fiber ratios to the mechanical property. The results show that the difference of the tension and blending strength in the same direction, among composite boards in different fiber proportions, is about 1~10Mpa; the difference in the same fiber proportion, between transverse and longitudinal, vary within a wide range from 10Mpa to 30Mpa. The results of variance analysis have also proved the conclusion, the difference between transverse and longitudinal is more significant than the difference among different fiber proportions. In the similar study, the significance hadn’t been seen sufficiently, so this paper provides reference to the actual application of the composite board.

Topical Mitomycin-C Use in Surgery of the Anterior Commisure

Results: Nineteen manifested anterior webs during treatment, whereas six were successfully treated with mitomycin c without developing a web. 84% demonstrated resolution of the AGW. Conversely three patients developed new web formation following application of mitomycin C, all of which were subsequently cleared. Only one patient was recalcitrant to therapy and required surgical lysis with keel placement. No patients developed laryngeal cancer during our study period.

Endoscopic Laser Anterior Commissurotomy for Anterior Glottic Web: One-Stage Procedure

The conventional method for preventing web formation after anterior glottic web surgery is keel insertion. However, this presents risks of airway compromise and granulation tissue formation, which could necessitate tracheotomy in addition to a secondary procedure for keel removal. We introduce a novel, 1-stage endoscopic laser anterior commissurotomy for preventing anterior glottic web re-formation. Twenty patients with glottic webs involving the anterior commissure were studied. The lesions were removed by transoral carbon dioxide laser microsurgery. In all patients, the anterior glottic web was vaporized along with the inner perichondrium of the thyroid cartilage over the anterior commissure area, creating a raw vertical break "alley" between the anterior vocal folds that measured between 0.3 and 0.5 cm in width and between 0.8 and 2 cm in length. The preoperative and postoperative vocal folds and voice quality were evaluated by videostrobolaryngoscopy and voice recordings. All 20 patients had anterior glottic webs ranging from 11% to 64% of the length from the anterior commissure to the vocal process. None of the patients developed restenosis at the anterior commissure of a severity similar to that of the initial lesion during follow-up (mean, 13 months; range, 3 to 44 months).All patients except 1 reported satisfaction with their voice improvement. Outcome analysis revealed that partial re-formation of the web was noted in 4 patients. One-stage, endoscopic laser anterior commissurotomy was effective and relatively safe for removing glottic webs, for preventing anterior glottic web re-formation, and for improving vocal fold performance among our patients.

Surface Modification of Polypropylene Non-woven Substrates by Padding with Antistatic Agents for Deposition of Polyvinyl Alcohol Nanofiber Webs by Electrospinning

In recent years, the electrospinning process has become one of the most interesting processes to obtain nanofiber webs with interesting properties for uses in a wide variety of industrial sectors such as filtration, chemical barriers, medical devices, etc., as a consequence of the relatively high surface-to-volume ratio. Among the wide variety of polymers, polyvinyl alcohol (PVA) offers good advantages since it is water-soluble and this fact enables easy processing by electrospinning. There are many variables and parameters to be considered in order to optimize PVA nanofiber webs: some of them are related to the polymer solution, some others are related to the process, and some of them are related to the collector substrate. In this work a study on the effects of two different surface pre-treatments on a non-woven polypropylene substrate as a collector of PVA nanofiber webs has been carried out. In particular, a chemical treatment with anionic antistatics and a physical treatment with low-pressure plasma have been investigated. The effects of these pre-treatments on morphology of PVA nanofiber webs have been evaluated by scanning electron microscopy. Results show that surface resistivity is one of the main parameters influencing the web formation as well as the nature of the electric charge achieved by the pre-treatment. The plasma treatment promotes changes in surface resistivity but it is not enough for good web deposition. Chemical pre-treatment (padding) with anionic antistatic leads to a decrease in surface resistivity up to values in the 1 × 10 9— 1 × 1011 Ω which is enough for good nanofiber deposition.

The power spectrum of the cosmic microwave background Kolmogorov maps: possible clue to correlation of voids

The power spectrum is obtained for the Kolmogorov stochasticity parameter map for WMAP's cosmic microwave background (CMB) radiation temperature datasets. The interest for CMB Kolmogorov map is that it can carry direct information about voids in the matter distribution, so that the correlations in the distribution of voids have to be reflected in the power spectrum. Although limited by the angular resolution of the WMAP, this analysis shows the possibility of acquiring this crucial information via CMB maps. Even the already obtained behavior, some of which is absent in the simulated maps, can influence the development of views on the void correlations at the large-scale web formation.

Anatomical variations of medial umbilical ligament: clinical significance in laparoscopic exploration of children

The anatomy and clinical significance of obliterated umbilical artery called as medial umbilical ligament (MUL) have not been documented well in literature. In this study, we investigated anatomical variations of MUL determined by laparoscopic exploration of abdomen in children and anatomy dissection on cadaver. The anatomy of MUL was investigated in a total of 126 patients including 41 retrospective cases. All 126 patients had laparoscopic exploration for a lower abdominal pathology. In retrospective group, videos demonstrating clearly both MULs and the region during laparoscopic exploration were selected. A dissection on an adult male cadaver was also performed. A preliminary grading scale of anatomical appearance of MUL was obtained. In grade 0, patients had no visible ligament (n = 14); in grade 1, MUL was a fibrous cord without a web formation (n = 63); in grade 2, MUL was a fibrous cord with a web (n = 49). MULs on both sides of the lower abdominal wall were symmetrical in all cases except one having a cloacal anomaly. This case had a solitary MUL on the right side. A MUL with a fibrous cord and significant web may cause technical difficulties and narrow the working space in laparoscopic exploration of children. It may also affect the surgeon's preference on trocar locations. In all grades of anatomical variation of MUL, formation of the ligament on both sides of the lower abdominal wall is similar. If there is a single umbilical artery, it becomes a solitary MUL after birth, and the possibility of associated malformations, especially urogenital abnormalities increases in such cases.

Prevention of anterior glottic stenosis after CO2 laser cordectomy with chitosan

To observe the effect of immediate topical application of chitosan on preventing anterior glottic stenosis (AGS) after microsurgical resection of both vocal fold with CO2 laser, including the anterior commissure, in a canine model. Sixteen canine larynges were injured by microresecting procedure of both vocal folds with CO2 laser. The dogs were randomly divided into two groups, chitosan group and control group. The chitosan and isotonic sodium chloride solution (control) were used for 5 minutes immediately after surgery. One week after the initial surgery, three dogs in each group were randomly selected , ultrastructure of fibroblast were examined with transmission electronic microscope and expression of basic fibroblast growth factor (bFGF) and transforming growth factor beta1 (TGF-beta1) were evaluated by enzyme-linked immunosorbent assay (ELISA). Three weeks after surgery, the rest dogs' glottic web were lysed and repeatedly treated with chitosan and isotonic sodium chloride solution respectively. The glottic wound healing and AGS formation were examined every week, and all larynges were harvested and examined histologically six weeks after the initial surgery. Transmission electronic microscope examination of the ultrastructure of fibroblast indicated that chitosan inhibited the proliferation of fibroblast. Chitosan increased the expression of bFGF and TGF-beta1, and bFGF and TGF-beta1 in chitosan group, which was significantly higher than that in control group (z=-2.887 and -2.005, P=0.002 and 0.041). Chitosan decreased the extent of AGS formation. Three weeks after the surgery, the AGS lesion in the control group affected mean 49% of the length of the vocal folds from the anterior commissure to the vocal process, while chitosan group affected mean 7%, which was significantly less than the extent of web formation in the control group, (z=-2.619, P=0.008). The grade of collagen content in chitosan group was significantly lower than that in control group (P=0.003). Chitosan is effective in preventing AGS after CO2 laser cordectomy.

50 Years Ago in The Journal of Pediatrics: Budd-Chiari Syndrome

50 Years Ago in The Journal of Pediatrics: Budd-Chiari Syndrome

Congenital Common Bile Duct Web in Association with Hepatobiliary Pancreatic Ductal Anomalies

Congenital webs are extremely rare anomalies of the extrahepatic ductal system. As the vast majority of such cases are asymptomatic, detection is usually incidental during surgery for some other cause. In a young boy presenting with features of cholangitis, a congenital common bile duct web was discovered on T-tube cholangiogram. Further anomalies of the intrahepatic and pancreatic ductal systems were also detected. Since all known causes of acquired web formation were excluded, a congenital origin of the web was assumed and the patient is continuing to do well after a follow-up of 22 months.

Outcome of laryngeal web resection with mucosal apposition for treatment of airway obstruction in dogs: 15 cases (1992–2006)

To evaluate long-term clinical outcome in dogs with upper airway obstruction treated with laryngeal web resection and mucosal apposition. Retrospective case series. 15 client-owned dogs with laryngeal web formation. Medical records of dogs with laryngeal webs treated with a single procedure of web resection with mucosal apposition by use of a ventral laryngotomy were reviewed. Signalment, history, clinical signs, intraoperative complications, postoperative complications, and hospitalization time were recorded. Owners were interviewed 6 months to 6 years after surgery. Most dogs had a history of oral ventriculocordectomy. Duration of clinical signs ranged from 3 months to 3 years. The most common clinical sign reported was exercise intolerance. Postoperative complications were observed in 4 dogs. Follow-up information was available in 10 dogs, and clinical outcome was classified as excellent in 7 and good in 3. A single surgical procedure of web resection with mucosal apposition for the treatment of laryngeal web formation in dogs resulted in low morbidity and was associated with a good to excellent outcome.

A Dynamic View of Hepatitis C Virus Replication Complexes

Hepatitis C virus (HCV) replicates its genome in a membrane-associated replication complex (RC). Specific membrane alterations, designated membranous webs, represent predominant sites of HCV RNA replication. The principles governing HCV RC and membranous web formation are poorly understood. Here, we used replicons harboring a green fluorescent protein (GFP) insertion in nonstructural protein 5A (NS5A) to study HCV RCs in live cells. Two distinct patterns of NS5A-GFP were observed. (i) Large structures, representing membranous webs, showed restricted motility, were stable over many hours, were partitioned among daughter cells during cell division, and displayed a static internal architecture without detectable exchange of NS5A-GFP. (ii) In contrast, small structures, presumably representing small RCs, showed fast, saltatory movements over long distances. Both populations were associated with endoplasmic reticulum (ER) tubules, but only small RCs showed ER-independent, microtubule (MT)-dependent transport. We suggest that this MT-dependent transport sustains two distinct RC populations, which are both required during the HCV life cycle.

Matching of separatrix map and resonant dynamics, with application to global chaos onset between separatrices

We have developed a general method for the description of separatrix chaos, based on the analysis of the separatrix map dynamics. Matching it with the resonant Hamiltonian analysis, we show that, for a given amplitude of perturbation, the maximum width of the chaotic layer in energy may be much larger than it was assumed before. We use the above method to explain the drastic facilitation of global chaos onset in time-periodically perturbed Hamiltonian systems possessing two or more separatrices, previously discovered [S. M. Soskin, O. M. Yevtushenko, and R. Mannella, Phys. Rev. Lett. 90, 174101 (2003)]. The theory well agrees with simulations. We also discuss generalizations and applications. The method may be generalized for single-separatrix cases. The facilitation of global chaos onset may be relevant to a variety of systems, e.g., optical lattices, magnetic and semiconductor superlattices, meandering flows in the ocean, and spinning pendulums. Apart from dynamical transport, it may facilitate noise-induced transitions and the stochastic web formation.

Benign proximal esophageal stenosis--mostly a complication of gastroesophageal reflux disease

Benign stenoses can occur anywhere in the oesophagus, but are most common in its distal part as a result of gastro-oesophageal reflux (GOR). It was the aim of this study to evaluate retrospectively the causes and incidence of benign stenosis of the proximal oesophagus (SPR) as well as its endoscopic and drug treatment. Between December 1989 and December 1997 a total of 17,413 patients were referred to the authors' hospital for oesophago-gastroduodenoscopy, 1024 of them (6%) for clarification of heartburn, regurgitation and/or dysphagia. 53 of these patients (5%) were found to have benign stenosis of the oesophagus requiring bougie dilatation, located in the lower third in 29 (55%), in the middle third in six (11%) and in the upper third in 18 (34%) patients. Causes of stenosis in the upper third were peptic stricture in nine (50%), heterotopic gastric mucosa in three (17%), caustic corrosion in three (17%), post-radiation in two (11%), and the result of web formation in one (6%). Endoscopic bougie dilatation was performed in all these patients, those with GOR additionally receiving 40 mg omeprazole daily. In those patients with nonpeptic benign stenosis/stricture lasting improvement of symptoms was achieved with one to three dilatation. But those with GOR needed a mean of 13 dilatations during a follow-up period averaging 61 months. Barrett's oesophagus (replacement of squamous by columnar epithelium) was found in five patients. No case of dysplasia was discovered. Laparoscopic fundoplication was performed in one woman in whom bougie dilatation had failed. Remission was maintained, as needed, by bougie and omeprazole in eight patients. In benign stenosis of the upper oesophagus endoscopic dilatation is the treatment of choice. In cases of peptic aetiology the administration of proton pump inhibitors is the optimal adjuvant method.

Micro−Nano Hierarchal Web of Activated Carbon Fibers for Catalytic Gas Adsorption and Reaction

A hierarchal web of activated carbon fibers is synthesized in which carbon nanofibers (CNF) are grown on micro activated carbon fibers (ACF) used as a substrate. A bed of ACF was first impregnated with nickel nitrate hexahydrate which was subsequently reduced to metallic nickel. Catalytic chemical vapor deposition (CVD) was then carried out at 1023 K using benzene as carbon source, which resulted in the growth of CNF. Conditions of hierarchal web formation were optimized by employing two different types of reactorsa perforated tube reactor with radially outward flow of gases and a perforated disc reactor providing a parallel flow. Both of these configurations were used for carrying out reduction and CVD. Our results show that relatively larger amount and uniformity of CNF could be obtained using the perforated disc reactor. Various analytical techniques including atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were employed to characterize the carbon web. The resulting ACF web is a hierarchical structure, which was tested for its NO removal capability by reduction. We found these carbon structures to be more efficient compared to the original ACF or ACF impregnated with metal.

In-office laryngeal surgery with the 585nm pulsed dye laser (PDL)

The 585nm pulsed dye laser (PDL) is a promising tool for in-office laryngeal surgery. Data with respect to the safety and efficacy of the PDL for office laryngeal use is sparse. The purpose of this study is to review our experience with unsedated office PDL surgery. Records of individuals undergoing in-office PDL between September 1, 2004, and September 1, 2006 were abstracted from a clinical database. Forty-seven patients underwent 117 treatments. The most common indications were recurrent respiratory papillomatosis (RRP), Reinke's edema, and vocal fold polyps. One hundred and four of 117 procedures were felt to be a success ablating all disease. Thirteen treatments required early termination. The most common factor responsible for termination was an inability to achieve a comfortable level of anesthesia. One patient with Reinke's edema developed postprocedure stridor that required a 3-day hospital admission for observation and corticosteroids. There was no incidence of any vocal fold scarring, web formation, or other complications. The 585nm PDL is a promising tool for in-office treatment of various laryngeal disorders. Complications are rare.

Fiber and web formation of melt‐blown thermoplastic polyurethane polymers

AbstractThe goal of this research was to determine the fiber and web properties of melt‐blown (MB) thermoplastic polyurethane (TPU) polymer as dependent on the MB processing conditions. The relationships between the MB fiber properties and the MB process conditions, such as the die‐to‐collector distance and the velocity of the MB TPU fiber in the spin line, were measured and estimated on the basis of the air velocity and air temperature, respectively. Consequently, this study provided fundamental guidelines of heat, air flow, and distance conditions of the MB process for the production of commercially acceptable MB TPU nonwovens. More specifically, the essential insight into the MB process was fundamentally valid for the MB TPU process; however, the inherent heat sensitivity of the TPU polymer brought more complexity at fiber and web formation than the conventional polyolefin MB process. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

Formation of Fiberwebs from Staple Fibers with Controlled Fiber Orientation Using Electrostatic Forces: Theoretical Analysis

Current web formation technologies used by the nonwovens industry do not provide positive control over fiber orientation and it is difficult to generate lightweight webs from staple fibers with these processes. The aim of this research is to develop new methods of fiberweb formation using electrostatic force, where orientation and orientation distribution of staple fibers are positively controlled. We carried out theoretical analysis and constructed computer models for this approach. Our analysis considered the effects of geometric configurations of fiber feeding and web formation zone, electrostatic and airflow field parameters, and the fiber's initial conditions at the feeding zone on fiber orientation. The theoretical analyses and computer modeling of the electrostatic web forming process provide better insights into this method and serve as a powerful tool for engineering development. Numerical results were obtained and presented for a range of processing variables.