Needleless electrospinning of uniform nanofibers using spiral coil spinnerets

Polyvinyl alcohol nanofibers were prepared by a needleless electrospinning technique using a rotating spiral wire coil as spinneret. The influences of coil dimension (e.g., coil length, coil diameter, spiral distance, and wire diameter) and operating parameters (e.g., applied voltage and spinning distance) on electrospinning process, nanofiber diameter, and fiber productivity were examined. It was found that the coil dimension had a considerable influence on the nanofiber production rate, but minor effect on the fiber diameter. The fiber production rate increased with the increased coil length or coil diameter, or the reduced spiral distance or wire diameter. Higher applied voltage or shorter collecting distance also improved the fiber production rate but had little influence on the fiber diameter. Compared with the conventional needle electrospinning, the coil electrospinning produced finer fibers with a narrower diameter distribution. A finite element method was used to analyze the electric field on the coil surface and in electrospinning zone. It was revealed that the high electric field intensity was concentrated on the coil surface, and the intensity was highly dependent on the coil dimension, which can be used to explain the electrospinning performances of coils. In addition, PAN nanofibers were prepared using the same needleless electrospinning technique to verify the improvement in productivity.<br /

Needleless electrospinning and direct electrospinning of nanofiber yarns

Electrospinning is a simple, but efficient and versatile, technology to produce polymeric nanofibers for widely diverse applications in both textile and non-textile areas [1]. This technique has been shown many advantages such as universality in processing polymeric materials, eases of controlling the fiber diameter and functionalizing nanofibers through adjusting solution composition for electrospinning, and flexibility to generate fibrous membranes of various geometries. Although the novel applications of electrospun nanofibers have been extensively explored [2], the technology development for mass electrospinning of nanofibers has been hampered

A Review on the Mechanical Behaviour of Bamboo Reinforced Concrete Beams

In light of the increasing demand for sustainable building materials, the effectiveness of bamboo utilization in various fields has become the object of scientists’ close attention. The increased interest in bamboo is explained by its sustainable characteristics, which make it the most preferred material for environmentally friendly and costeffective construction compared to conventional ones. Applicability of bamboo is vast and diverse: from decoration and furniture to structural members and reinforcement. Due to the low price, rich resources, and high elasticity, bamboo culms have also been used as an alternative to steel reinforcement in concrete structures. Extensive research has been done to assess feasibility of bamboo reinforcement in structural elements made of concrete. This article discusses the mechanical properties of three types of structural bamboo reinforced concrete (BRC) beams. Existing original papers on the mechanical behaviour of structural BRC members were studied, and the fundamental properties including typical failure modes, reasons of failure, load-displacement relationships, and influencing factors were discussed and described. Observations and conclusions of the review will contribute to deep understanding of structural feasibility of BRC beams and serve as a base for future research

Severe adult ileosigmoid intussusception prolapsing from the rectum: A case report

Intussusception is a pediatric condition that rarely presents in adults. In this article, we report a case of a 36 year-old man initially presenting with abdominal pain and rectal prolapse, however, surgical reduction of the rectal prolapse did no relief his symptoms. Physical examination, abdominal plain film, barium enema and colonoscopy confirmed the presence of a large intra-abdominal mass, but the origin of the mass was revealed only upon laparotomy. During the surgery, it was noted that the ileum and the sigmoid colon was connected by a 15 cm × 12cm mass, covered by an extremely dilated intestinal tissue. The resected tissue pathology demonstrated a 9 cm × 6 cm × 5 cm submucosal lipoma at the ileocecal junction without evidence of malignancy. The patient's post-surgical course was uneventful. Diagnostic and therapeutic problems related to adult intussusception are reviewed

Glass-ceramic Optical Fiber Containing Ba2 TiSi2O8 Nanocrystals for Frequency Conversion of Lasers

A glass-ceramic optical fiber containing Ba2TiSi2O8 nanocrystals fabricated using a novel combination of the melt-in-tube method and successive heat treatment is reported for the first time. For the melt-in-tube method, fibers act as a precursor at the drawing temperature for which the cladding glass is softened while the core glass is melted. It is demonstrated experimentally that following heat treatment, Ba2TiSi2O8 nanocrystals with diameters below 10 nm are evenly distributed throughout the fiber core. Comparing to the conventional rod-in-tube method, the melt-in-tube method is superior in terms of controllability of crystallization to allow for the fabrication of low loss glass-ceramic fibers. When irradiated using a 1030 nm femtosecond laser, an enhanced green emission at a wavelength of 515 nm is observed in the glass-ceramic fiber, which demonstrates second harmonic generation of a laser action in the fabricated glass-ceramic fibers. Therefore, this new glass-ceramic fiber not only provides a highly promising development for frequency conversion of lasers in all optical fiber based networks, but the melt-in-tube fabrication method also offers excellent opportunities for fabricating a wide range of novel glass-ceramic optical fibers for multiple future applications including fiber telecommunications and lasers