다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

During the resorbable-polymer-boom of the 1970s and 1980s, polycaprolactone (PCL) was used in the biomaterials field and a number of drug-delivery devices. Its popularity was soon superseded by faster resorbable polymers which had fewer perceived disadvantages associated with long term degradation (up to 3-4 years) and intracellular resorption pathways; consequently, PCL was almost forgotten for most of two decades. Recently, a resurgence of interest has propelled PCL back into the biomaterials-arena. The superior rheological and viscoelastic properties over many of its aliphatic polyester counterparts renders PCL easy to manufacture and manipulate into a large range of implants and devices. Coupled with relatively inexpensive production routes and FDA approval, this provides a promising platform for the production of longer-term degradable implants which may be manipulated physically, chemically and biologically to possess tailorable degradation kinetics to suit a specific anatomical site. This review will discuss the application of PCL as a biomaterial over the last two decades focusing on the advantages which have propagated its return into the spotlight with a particular focus on medical devices, drug delivery and tissue engineering.

The return of a forgotten polymer : Polycaprolactone in the 21st century

Nanoparticles can influence the properties of polymer materials by a variety of mechanisms. With fullerene, carbon nanotube, and clay or graphene sheet nanocom- posites in mind, we investigate how particle shape influences the melt shear viscosity ! and the tensile strength " , which we determine via molecular dynamics simula- tions. Our simulations of compact (icosahedral), tube or rod-like, and sheet-like model nanoparticles, all at a volume fraction # ! 0.05, indicate an order of magnitude increase in the viscosity ! relative to the pure melt. This finding evidently can not be explained by continuum hydrodynamics and we provide evidence that the ! increase in our model nanocomposites has its origin in chain bridging between the nanopar- ticles. We find that this increase is the largest for the rod-like nanoparticles and least for the sheet-like nanoparticles. Curiously, the enhancements of ! and " exhibit opposite trends with increasing chain length N and with particle shape anisotropy. Evidently, the concept of bridging chains alone cannot account for the increase in " and we suggest that the deformability or flexibility of the sheet nanoparticles con- tributes to nanocomposite strength and toughness by reducing the relative value of the Poisson ratio of the composite. The molecular dynamics simulations in the present work focus on the reference case where the modification of the melt structure associ- ated with glass-formation and entanglement interactions should not be an issue. Since many applications require good particle dispersion, we also focus on the case where the polymer-particle interactions favor nanoparticle dispersion. Our simulations point to a substantial contribution of nanoparticle shape to both mechanical and processing prop- erties of polymer nanocomposites. © 2007 Wiley Periodicals, Inc." J Polym Sci Part B: Polym

http://absimage.aps.org/image/MAR07/MWS_MAR07-2006-002162.pdf

The Effect of Nanoparticle Shape on Polymer-Nanocomposite Rheology and Tensile Strength

Multicolor bandgap fluorescent carbon quantum dots (MCBF-CQDs) from blue to red with quantum yield up to 75% are synthesized using a solvothermal method. For the first time, monochrome electroluminescent light-emitting diodes (LEDs) with MCBF-CQDs directly as an active emission layer are fabricated. The maximum luminance of blue LEDs reaches 136 cd m-2 , which is the best performance for CQD-based monochrome electroluminescent LEDs.

Bright Multicolor Bandgap Fluorescent Carbon Quantum Dots for Electroluminescent Light-Emitting Diodes

Innovative materials of this era for toughening the epoxy matrix: A review

High performance epoxy composites are now a days a must in several industrial applications. In the present work electrospun polyimide (PI) nanofibers with excellent thermal and mechanical properties was used as a reinforcement in epoxy matrix via a simple mechanical mixing followed by thermal curing method. Well defined electrospun nanofibers of aromatic polyimide (PI) were successfully prepared from electrospinning Poly (amic acid) (PAA) and subsequent thermal treatment. The fiber morphology was analyzed using Transmission electron microscopy (TEM) and Atomic force microscopy (AFM). PI/epoxy nanocomposites with different PI loadings were prepared using chopped PI mats. The dynamic mechanical performance of these PI/epoxy composites was investigated to determine the influence of PI fibers in reinforcing the epoxy matrix. The fracture toughness of these composites displayed a note worthy improvement of 20 % at 1 w% loaded samples and the surface of the fractured samples was investigated by Scanning electron microscope. The rheological properties of these systems show a tremendous increase in the storage and loss modulus when compared to neat systems. In addition flow models were employed to model the rheological data and the comparison was made with the experimental data.

Enhanced visco-elastic and rheological behavior of epoxy composites reinforced with polyimide nanofiber

Triblock copolymer grafted Graphene oxide as nanofiller for toughening of epoxy resin

Superhydrophobic graphene-based materials with self-cleaning and anticorrosion performance: An appraisal of neoteric advancement and future perspectives

The discovery of graphene, a well-known two dimensional material (2D) and its subsequent utility has extended the significance of other 2D materials. Molybdenum disulﬁde (MoS2 ), an important member of transition metal dichalcogenides (TMD) is having a structure analoguos to graphene. The excellent electronic, optical, thermal and mechanical properties of MoS 2 makes it a remarkable material in almost all these areas. Currently, MoS2 based polymer nanocomposites have been gaining research interest owing to the outstanding reinforcement ability of nanosized MoS 2. In this review, we intend to cast light on the various synthesis and functionalization methods of MoS2 nanosheets. We have also consolidated the various polymer/MoS2 nanocomposites, their applications and future proepectives in a comprehensive way.

Jitha S. Jayan

Papers

Innovative materials of this era for toughening the epoxy matrix: A review

Enhanced visco-elastic and rheological behavior of epoxy composites reinforced with polyimide nanofiber

Triblock copolymer grafted Graphene oxide as nanofiller for toughening of epoxy resin

Superhydrophobic graphene-based materials with self-cleaning and anticorrosion performance: An appraisal of neoteric advancement and future perspectives

MoS2: Advanced nanofiller for reinforcing polymer matrix