scholarly journals Bimodal Porous Scaffolds by Sequential Electrospinning of Poly(glycolic acid) with Sucrose Particles

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
B. Wulkersdorfer ◽  
K. K. Kao ◽  
V. G. Agopian ◽  
A. Ahn ◽  
J. C. Dunn ◽  
...  
Keyword(s):  
Glycolic Acid ◽  
Three Dimensional ◽  
Porous Scaffolds ◽  
Hybrid Technique ◽  
Electrospun Scaffolds ◽  
Limited Application ◽  
Novel Method ◽  
Particulate Leaching ◽  
The One ◽  
Laminated Structures

Electrospinning is a method to produce fine, biopolymer mesh with a three-dimensional architecture that mimics native extra-cellular matrix. Due to the small fiber diameter created in this process, conventional electrospun scaffolds have pore sizes smaller than the diameter of most cells. These scaffolds have limited application in tissue engineering due to poor cell penetration. We developed a hybrid electrospinning/particulate leaching technique to create scaffolds with increased porosity and improved cellular ingrowth. Poly(glycolic acid) (PGA) and a sucrose-ethanol suspension were electrospun in equal, alternating sequences at intervals of one, two, and ten minutes each. The scaffolds revealed fiber mesh with micropores of 10 m and uniformly distributed sucrose particles. Particulate leaching of sucrose from the one- or two-minute scaffolds revealed honeycomb structures with interconnected macropores between 50 and 250 m. Sucrose leaching from the ten-minute scaffolds resulted in laminated structures with isolated macropores between 200 and 350 m. Macropore size was directly proportional to the duration of the sucrose spinning interval. After 24 hours of cell culture, conventionally spun scaffolds demonstrated no cellular penetration. Conversely, the PGA/sucrose scaffolds demonstrated deep cellular penetration. This hybrid technique represents a novel method of generating electrospun scaffolds with interconnected pores suitable for cellular ingrowth.

Hydroxyapatite Nano-Particles Coating on the Pore Surface Within Poly(DL-lactic-co-glycolic acid) Scaffold

2007 ◽  
Vol 334-335 ◽  
pp. 1237-1240 ◽  
Author(s):  
Jia Shen Li ◽  
Arthur F.T. Mak
Keyword(s):  
Pore Size ◽  
Glycolic Acid ◽  
Pore Wall ◽  
Nano Particles ◽  
Porous Scaffolds ◽  
High Porosity ◽  
Pore Surface ◽  
Plga Scaffold ◽  
Novel Method

This paper describes a novel method for coating hydroxyapatite (HA, Ca10(PO4)6(OH)2) nano-particles onto poly(DL-lactic-co-glycolic acid) (PLGA) scaffold. Paraffin micro-spheres were used as porogens to create porous scaffolds and as vehicles to transfer HA into PLGA scaffold. HA nano-particles / 50% ethanol suspension was mixed with paraffin micro-spheres. The paraffin micro-spheres / HA suspension were pressed together to form a paraffin scaffold. After it was dried, the HA was coated on the surface of the paraffin spheres. Then, PLGA solution was cast into the inter space among the paraffin micro-spheres and then the solvent was evaporated. Afterwards, the paraffin micro-spheres were dissolved and removed. PLGA scaffolds with controlled pore size, good interconnectivity and high porosity were obtained. The HA nano-particles were transferred from the paraffin surface to the surface of the pore wall throughout the PLGA scaffold.

Thermal Processing of Tissue Engineering Scaffolds

2010 ◽  
Vol 133 (3) ◽  
Author(s):  
Alisa Morss Clyne
Keyword(s):  
Tissue Engineering ◽  
Thermal Processing ◽  
Three Dimensional ◽  
Processing Parameters ◽  
High Pressure Processing ◽  
Porous Scaffolds ◽  
Tissue Engineering Scaffolds ◽  
Thermally Induced ◽  
Advantages And Disadvantages ◽  
Particulate Leaching

Tissue engineering requires complex three-dimensional scaffolds that mimic natural extracellular matrix function. A wide variety of techniques have been developed to create both fibrous and porous scaffolds out of polymers, ceramics, metals, and composite materials. Existing techniques include fiber bonding, electrospinning, emulsion freeze drying, solvent casting/particulate leaching, gas foaming/particulate leaching, high pressure processing, and thermally induced phase separation. Critical scaffold properties, including pore size, porosity, pore interconnectivity, and mechanical integrity, are determined by thermal processing parameters in many of these techniques. In this review, each tissue engineering scaffold preparation method is discussed, including recent advancements as well as advantages and disadvantages of the technique, with a particular emphasis placed on thermal parameters. Improvements on these existing techniques, as well as new thermal processing methods for tissue engineering scaffolds, will be needed to provide tissue engineers with finer control over tissue and organ development.

Fabrication of poly(lactic acid) scaffolds by a modified solvent casting/porogen leaching method

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
Xinghou Gong ◽  
Chak Yin Tang ◽  
Chi Tak Wong ◽  
William Weijia Lu ◽  
Yugang Zhang ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Pore Size ◽  
Three Dimensional ◽  
Poly Lactic Acid ◽  
Porous Scaffolds ◽  
Solvent Casting ◽  
Subsequent Removal ◽  
Modified Method ◽  
Good Accordance ◽  
Particulate Leaching

AbstractA modified solvent casting/particulate leaching (SC/PL) method was developed to fabricate thick three-dimensional poly(lactic acid) (PLA) scaffolds with controlled pore size and porosity, and much shorter processing time. The pasty mixture of PLA/CHCl3/NaCl was sealed in a Buchner funnel by a piston with a suction flask connected. A vacuum pump was used to facilitate the volatilization of solvent. The scaffolds were obtained by subsequent removal of NaCl in deionized water. The pore size within the scaffold was in good accordance with the particle size of NaCl (< 210, 210~310, 310~420 and 420~500 μm), all of which had more than 89 % of porosity, 1.95 ± 0.2 MPa of compressive modulus and non-cytotoxic to L929 cells. To demonstrate the applicability of the SC/VV/PL method, thick cylindrical and tubular porous scaffolds have been produced in this study. Compared with the traditional SC/PL without vacuum volatilization, the modified method, namely, solvent casting/vacuum volatilization/particulate leaching (SC/VV/PL) method, provide a more efficient way to fabricate thick scaffolds.

scholarly journals Individualized male dress shirt adjustments using a novel method for measuring shoulder shape

2017 ◽  
Vol 29 (2) ◽  
pp. 215-225 ◽  
Author(s):  
KyoungOk Kim ◽  
Noriaki Innami ◽  
Masayuki Takatera ◽  
Tadaharu Narita ◽  
Midori Kanazawa ◽  
...  
Keyword(s):  
Body Shape ◽  
Three Dimensional ◽  
Measuring Device ◽  
Content Type ◽  
Japanese Male ◽  
Novel Method ◽  
The Common ◽  
Wear Evaluation ◽  
The One ◽  
Shoulder Angle

Purpose The purpose of this paper is to investigate the current challenges to making individualized men’s dress shirt adjustments, and devised a novel measurement method to assess shoulder shape. Design/methodology/approach To understand the common complaints about ready-to-wear dress shirts, a wear evaluation with 15 Japanese males was performed. The shoulder components of these shirts could not be adjusted using any currently available measurement methods. The three-dimensional body shape of two subjects who had a problem with the shoulder of ready-to-wear shirts was compared with a dummy designed to represent the average Japanese male. Findings The authors determined that one of the subjects with an incompatible shoulder fit had a shoulder point (SP) line that was anterior to the one measured on the average dummy. The other subject had a smaller shoulder angle than the average dummy. To effectively measure the wearer’s shoulder characteristics, the authors devised a new measuring device that can measure the shoulder angle and its degree of forward thrust. With this device, it was possible to understand the wearers’ shoulder types and make appropriate dress shirt adjustments. Originality/value The authors devised a new measuring device to assess shoulder angle and forward thrust, qualities that previously could not be measured without three-dimensional analysis. Using this device, it was possible to understand the wearers’ shoulder types and make appropriate dress shirt adjustments.

Diffraction contrast of dislocations in icosahedral quasicrystals

1990 ◽  
Vol 48 (4) ◽  
pp. 454-455
Author(s):  
K. Urban ◽  
Z. Zhang ◽  
M. Wollgarten ◽  
D. Gratias
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Complete Characterization ◽  
Extinction Condition ◽  
Burgers Vector ◽  
Diffraction Contrast ◽  
Lattice Geometry ◽  
Reference Space ◽  
Icosahedral Quasicrystals ◽  
The One

Recently dislocations have been observed by electron microscopy in the icosahedral quasicrystalline (IQ) phase of Al65Cu20Fe15. These dislocations exhibit diffraction contrast similar to that known for dislocations in conventional crystals. The contrast becomes extinct for certain diffraction vectors g. In the following the basis of electron diffraction contrast of dislocations in the IQ phase is described. Taking account of the six-dimensional nature of the Burgers vector a “strong” and a “weak” extinction condition are found.Dislocations in quasicrystals canot be described on the basis of simple shear or insertion of a lattice plane only. In order to achieve a complete characterization of these dislocations it is advantageous to make use of the one to one correspondence of the lattice geometry in our three-dimensional space (R3) and that in the six-dimensional reference space (R6) where full periodicity is recovered . Therefore the contrast extinction condition has to be written as gpbp + gobo = 0 (1). The diffraction vector g and the Burgers vector b decompose into two vectors gp, bp and go, bo in, respectively, the physical and the orthogonal three-dimensional sub-spaces of R6.

Exploring the Multidimensional Facets of Authoritarianism: Authoritarian Aggression and Social Dominance Orientation

2008 ◽  
Vol 67 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Stefano Passini
Keyword(s):  
Social Dominance ◽  
Factor Model ◽  
Three Dimensional ◽  
Social Dominance Orientation ◽  
Model Fit ◽  
Regression Analyses ◽  
One Dimensional ◽  
Confirmatory Factor ◽  
The One ◽  
Better Than

The relation between authoritarianism and social dominance orientation was analyzed, with authoritarianism measured using a three-dimensional scale. The implicit multidimensional structure (authoritarian submission, conventionalism, authoritarian aggression) of Altemeyer’s (1981, 1988) conceptualization of authoritarianism is inconsistent with its one-dimensional methodological operationalization. The dimensionality of authoritarianism was investigated using confirmatory factor analysis in a sample of 713 university students. As hypothesized, the three-factor model fit the data significantly better than the one-factor model. Regression analyses revealed that only authoritarian aggression was related to social dominance orientation. That is, only intolerance of deviance was related to high social dominance, whereas submissiveness was not.

A Novel Method for the Rapid Purification of Human and Rat Fibrin(OGEN) Degradation Products in High Yields

1979 ◽  
Author(s):  
W. Nieuwenhuizen ◽  
I. A. M. van Ruijven-Vermeer ◽  
F. Haverkate ◽  
G. Timan
Keyword(s):  
Degradation Products ◽  
Complete Separation ◽  
Purification Method ◽  
Amino Terminal ◽  
Novel Method ◽  
Rapid Purification ◽  
The One ◽  
High Yields ◽  
Size Heterogeneity ◽  
D Dimer

A novel method will be described for the preparation and purification of fibrin(ogen) degradation products in high yields. The high yields are due to two factors. on the one hand an improved preparation method in which the size heterogeneity of the degradation products D is strongly reduced by plasmin digestion at well-controlled calcium concentrations. At calcium concentrations of 2mM exclusively D fragments, M.W.= 93-000 (Dcate) were formed; in the presence of 1OmM EGTA only fragments M.W.= 80.000 (D EGTA) were formed as described. on the other hand a new purification method, which includes Sephadex G-200 filtration to purify the D:E complexes and separation of the D and E fragments by a 16 hrs. preparative isoelectric focussing. The latter step gives a complete separation of D (fragments) (pH = 6.5) and E fragments (at pH = 4.5) without any overlap, thus allowing a nearly 100% recovery in this step. The overall recoveries are around 75% of the theoretical values. These recoveries are superior to those of existing procedures. Moreover the conditions of this purification procedure are very mild and probably do not affect the native configuration of the products. Amino-terminal amino acids of human Dcate, D EGTA and D-dimer are identical i.e. val, asx and ser. in the ratgly, asx and ser were found. E 1% for rat Dcate=17-8 for rat D EGTA=16.2 and for rat D- dimer=l8.3. for the corresponding human fragments, these values were all 20.0 ± 0.2.

Sea Urchins and Circuses: The Modernist Natural Histories of Jean Painlevé and Alexander Calder

2018 ◽  
Vol 13 (2) ◽  
pp. 187-211
Author(s):  
Patricia E. Chu
Keyword(s):  
New Media ◽  
Sea Urchins ◽  
Life Sciences ◽  
Three Dimensional ◽  
Machine Age ◽  
Avant Garde ◽  
History Of ◽  
And Performance ◽  
The One ◽  
Natural Historian

The Paris avant-garde milieu from which both Cirque Calder/Calder's Circus and Painlevé’s early films emerged was a cultural intersection of art and the twentieth-century life sciences. In turning to the style of current scientific journals, the Paris surrealists can be understood as engaging the (life) sciences not simply as a provider of normative categories of materiality to be dismissed, but as a companion in apprehending the “reality” of a world beneath the surface just as real as the one visible to the naked eye. I will focus in this essay on two modernist practices in new media in the context of the history of the life sciences: Jean Painlevé’s (1902–1989) science films and Alexander Calder's (1898–1976) work in three-dimensional moving art and performance—the Circus. In analyzing Painlevé’s work, I discuss it as exemplary of a moment when life sciences and avant-garde technical methods and philosophies created each other rather than being classified as separate categories of epistemological work. In moving from Painlevé’s films to Alexander Calder's Circus, Painlevé’s cinematography remains at the forefront; I use his film of one of Calder's performances of the Circus, a collaboration the men had taken two decades to complete. Painlevé’s depiction allows us to see the elements of Calder's work that mark it as akin to Painlevé’s own interest in a modern experimental organicism as central to the so-called machine-age. Calder's work can be understood as similarly developing an avant-garde practice along the line between the bestiary of the natural historian and the bestiary of the modern life scientist.

Sign in / Sign up

Export Citation Format

Share Document