Recent interests in process methodologies possessing the ability for forming scaffolds have gained a great deal of scientific attention. Essentially this has resulted from the realization that these constructs have much utility in the life sciences. In this letter, we elucidate a novel and versatile scaffold process fabrication methodology with a concentric jetting process that shows tremendous possibilities for forming stable composite scaffolds. Our studies combine a specially formulated medical grade PDMS (polydimethylsiloxane) medium together with this concentric jetting process demonstrating significant possibilities for controlled composite scaffold formation and deposition. Hence the results presented elucidate promising opportunities for using these scaffolds in the biomedical areas of research.

S. Arumuganathar

S. N. Jayasinghe

Aerodynamically Assisted Jet Fabrication and Deposition of Composite Scaffolds via Concentric Needles

The metallicity in semiconductors with respect to energy gap along <mml:math id="E1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>&#x0393;</mml:mi><mml:mo>&#x2192;</mml:mo><mml:mtext>X</mml:mtext></mml:mrow></mml:math> is used to calculate bulk modulus and gives reasonable results in agreement to that of experimental and
Cohen results.

Y. Al-Douri

Correlation between the Bulk Modulus and the Metallicity in Semiconductors

Polystyrene (PS)-based hybrid particles containing a large amount of Mg<mml:math id="E2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mrow><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:mtext>OH</mml:mtext></mml:mrow><mml:mo>)</mml:mo></mml:mrow></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math> powder treated with methylhydrogen polysiloxane (MHS) were fabricated by a bulk and subsequent suspension two-step polymerization method. All the particles fabricated showed spherical shape and their particle sizes were about 500&#x2009;<mml:math id="E3" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>&#x03BC;</mml:mi></mml:math>m, irrespective of the additive amount of the Mg<mml:math id="E4" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mrow><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:mtext>OH</mml:mtext></mml:mrow><mml:mo>)</mml:mo></mml:mrow></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math> powder modified with MHS (ST-1). The actual content of ST-1 powder incorporated inside
each kind of hybrid particle was almost the same as that in the raw mixture, and agglomeration of ST-1 powder
was hardly observed inside the hybrid particles. The compressive strength of the hybrid particles remained almost
unchanged, even when the ST-1 powder content increased from 10 to 50&#x2009;phr. Furthermore, a composite fabricated by employing the hybrid particles achieved homogenous distribution of ST-1 powder and showed a higher oxygen index than that of a composite fabricated by directly mixing of PS pellets and ST-1 powder.

Shuichi Kimura

Takeo Hyodo

Yasuhiro Shimizu

Makoto Egashira

Characterizations of Polystyrene-Based Hybrid Particles Containing Hydrophobic Mg <svg style="vertical-align:-3.27605pt" height="16.275" version="1.1" viewBox="0 0 43.787498 16.275" width="43.787498" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"><g transform="matrix(.017,-0,0,-.017,.062,12.137)"><path id="x28" d="M300 -147l-18 -23q-106 71 -159 185.5t-53 254.5v1q0 139 53 252.5t159 186.5l18 -24q-74 -62 -115.5 -173.5t-41.5 -242.5q0 -130 41.5 -242.5t115.5 -174.5z" /></g><g transform="matrix(.017,-0,0,-.017,5.944,12.137)"><path id="x4F" d="M381 665q131 0 226.5 -93t95.5 -239q0 -158 -96 -253t-238 -95q-137 0 -231 95t-94 238q0 142 92.5 244.5t244.5 102.5zM359 629q-89 0 -151 -74.5t-62 -208.5q0 -141 69 -233t175 -92q90 0 150.5 74t60.5 211q0 152 -69 237.5t-173 85.5z" /></g><g transform="matrix(.017,-0,0,-.017,18.489,12.137)"><path id="x48" d="M729 650v-28q-62 -5 -76 -19.5t-14 -75.5v-404q0 -62 13.5 -76t75.5 -19v-28h-268v28q65 5 79.5 19t14.5 76v199h-341v-199q0 -62 14 -76t76 -19v-28h-263v28q61 5 74.5 19t13.5 76v404q0 62 -14 76t-76 19v28h259v-28q-58 -5 -71 -19t-13 -76v-162h341v162&#xA;q0 61 -13.5 75.5t-72.5 19.5v28h261z" /></g><g transform="matrix(.017,-0,0,-.017,31.51,12.137)"><path id="x29" d="M275 270q0 -296 -211 -440l-19 23q75 62 116.5 174t41.5 243t-42 243t-116 173l19 24q211 -144 211 -440z" /></g><g transform="matrix(.012,-0,0,-.012,37.387,16.212)"><path id="x32" d="M412 140l28 -9q0 -2 -35 -131h-373v23q112 112 161 170q59 70 92 127t33 115q0 63 -31 98t-86 35q-75 0 -137 -93l-22 20l57 81q55 59 135 59q69 0 118.5 -46.5t49.5 -122.5q0 -62 -29.5 -114t-102.5 -130l-141 -149h186q42 0 58.5 10.5t38.5 56.5z" /></g></svg> Powder and Composites Fabricated by Employing Resultant Hybrid Particles

Cellulose aerogels are intriguing new materials produced by supercritical drying of regenerated cellulose obtained by solvent exchange of solid Lyocell moldings. From <mml:math id="E1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>N</mml:mi></mml:math>-methylmorpholine-<mml:math id="E2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>N</mml:mi></mml:math>-oxide solutions with cellulose contents between 1 and 12<mml:math id="E3" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>&#x0025;</mml:mi></mml:math>, dimensionally stable cellulose bodies are produced, in which the solution structure of the cellulose is largely preserved and transferred into the solid state. The specific density and surface of the obtained aerogels range from 0.05 to 0.26 g/<mml:math id="E4" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mrow><mml:mtext>cm</mml:mtext></mml:mrow><mml:mn>3</mml:mn></mml:msup></mml:mrow></mml:math> and from 172 to 284 <mml:math id="E5" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mtext>m</mml:mtext><mml:mn>2</mml:mn></mml:msup></mml:mrow></mml:math>/g, respectively, depending on the cellulose content of the Lyocell dopes and regeneration procedure. A reliable extraction and drying procedure using supercritical carbon dioxide, the advantageous use of NBnMO as stabilizer for the Lyocell dopes, and selected physical properties of the materials is communicated.

Falk Liebner

Antje Potthast

Thomas Rosenau

Emmerich Haimer

Martin Wendland

Ultralight-Weight Cellulose Aerogels from NBnMO-Stabilized Lyocell Dopes

Fundamental mechanisms of the pultrusion process using commingled yarns of polypropylene matrix and discontinuous
    flax fiber to produce thermoplastic profiles were investigated in numerical and experimental manners. Essential issue is the
    fact that all natural fibers are discontinuous by nature, which may negatively influence the processability. The pultrusion
    process will be only successful if the pulling force exerted on the solidified pultrudates can be transmitted to the regions of
    unmelted commingled yarns by &#x201C;bridging over&#x201D; those melted regions within the die. This can be realized by applying
    a sufficient number of small yarn bundles of high compactness rather than a thicker single bundle of lower compactness
    as the raw material. Furthermore, the possibility of adding extra melt into the yarn bundles by side-fed extrusion has been
    investigated showing that the impregnation can be improved only for the outer layers of yarns, which is owed to the high
    viscosity of the thermoplastic melt and the limited length of the die.

Tham Nguyen-Chung

Klaus Friedrich

G&#xFC;nter Mennig

Processability of Pultrusion Using Natural Fiber and Thermoplastic Matrix

Composites containing chlorophyll aggregates dispersed in amorphous silica are of interest because of their optical attractive properties. The silica powders added with chlorophyll species, prepared by the sol-gel method, were studied using X-ray diffraction, IR spectroscopy and differential temperature analysis. Silica xerogel samples were prepared using an ethanol/<mml:math id="E1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mtext>H</mml:mtext><mml:mn>2</mml:mn></mml:msub><mml:mtext>O</mml:mtext></mml:mrow></mml:math>/TEOS molar ratio of 4:11.6:1 and loaded with extracts from frozen spinach leaves. The silica xerogel microstructure of the powders was studied as a function of the annealing temperature. We found in our samples partial crystallization of the glass matrix in form of tridymite and cristobalite phases and quenching centers or nonfluorescing aggregates due to denaturation of photosystem promoted by chlorophyll decomposition after <mml:math id="E2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mrow><mml:mn>400</mml:mn></mml:mrow><mml:mo>&#x2218;</mml:mo></mml:msup><mml:mtext>C</mml:mtext></mml:mrow></mml:math>.

J. R. Mart&#xED;nez

G. Mart&#xED;nez-Casta&#xF1;&#xF3;n

G. Ortega-Zarzosa

J. A. de la Cruz-Mendoza

S. A. Palomares-S&#xE1;nchez

Facundo Ruiz

Structural Effects of Heat-Treated Silica Xerogel Induced by Incorporation of Chlorophyll Species

The effects of powders synthesis methods (urea-combustion synthesis (CS) and conventional solid-state (SS) reaction) on the sintering ability, microstructural features, and mechanical properties of <mml:math id="E1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mrow><mml:mtext>Al</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mtext>O</mml:mtext><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>, <mml:math id="E2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>MgAl</mml:mtext><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mtext>O</mml:mtext><mml:mn>4</mml:mn></mml:msub></mml:math> spinel, and 20&#x2009;wt.&#x25; Zr<mml:math id="E3" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>O</mml:mtext><mml:mn>2</mml:mn></mml:msub></mml:math>&#x2013;<mml:math id="E4" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>MgAl</mml:mtext><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mtext>O</mml:mtext><mml:mn>4</mml:mn></mml:msub></mml:math> upon sintering at 1625<mml:math id="E5" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mtext>C</mml:mtext><mml:mo>&#x2218;</mml:mo></mml:math> were investigated. X-ray diffraction (XRD), scanning electron microscopy (SEM), relative density (RD), apparent porosity and water absorption capacity, hardness, fracture toughness, and three-point bend test studies revealed the superior sintering ability of CS Zr<mml:math id="E6" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>O</mml:mtext><mml:mn>2</mml:mn></mml:msub></mml:math>-<mml:math id="E7" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>MgAl</mml:mtext><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mtext>O</mml:mtext><mml:mn>4</mml:mn></mml:msub></mml:math> composite powder as compared with one prepared by SS reaction. In contrast, single-phase powders obtained by SS reaction exhibit superior sintering ability over CS synthesized ones. The reasons for differences observed are discussed along this paper.

Ibram Ganesh

J. M. F. Ferreira

Influence of Phase Composition on Sintered Microstructure of Combustion Synthesized Oxides

Phosphor material CaA<mml:math id="E1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>l</mml:mtext><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mtext>O</mml:mtext><mml:mn>4</mml:mn></mml:msub></mml:math>:<mml:math id="E2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mtext>Eu</mml:mtext><mml:mrow><mml:mn>2</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:math> codoped with varying concentrations of <mml:math id="E3" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mtext>Nd</mml:mtext><mml:mrow><mml:mn>3</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:math> was prepared by solid-state reaction method. Prepared materials with 1 mol&#x25; <mml:math id="E4" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mtext>Eu</mml:mtext><mml:mrow><mml:mn>2</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:math> and <mml:math id="E5" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mtext>Nd</mml:mtext><mml:mrow><mml:mn>3</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:math> (0.5 to 5 mol&#x25;) show high brightness and long persistent luminescence. The phase and crystallinity of the synthesized materials were investigated by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Photoluminescence excitation and emission spectra were taken to investigate the luminescence characteristics. Broadband UV excited luminescence of the CaA<mml:math id="E6" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>l</mml:mtext><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mtext>O</mml:mtext><mml:mn>4</mml:mn></mml:msub></mml:math>:<mml:math id="E7" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mtext>Eu</mml:mtext><mml:mrow><mml:mn>2</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:math>, <mml:math id="E8" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mtext>Nd</mml:mtext><mml:mrow><mml:mn>3</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:math> was observed in the blue region (<mml:math id="E9" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>&#x03BB;</mml:mi><mml:mrow><mml:mo>max</mml:mo></mml:mrow></mml:msub></mml:math> = 440 nm) due to transitions from <mml:math id="E10" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mn>4</mml:mn><mml:mtext>f</mml:mtext><mml:msup><mml:mtext>&#x2009;</mml:mtext><mml:mn>6</mml:mn></mml:msup><mml:mtext>&#x2009;</mml:mtext><mml:mn>5</mml:mn><mml:msup><mml:mtext>d</mml:mtext><mml:mtext>1</mml:mtext></mml:msup></mml:math> to the <mml:math id="E11" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mn>4</mml:mn><mml:mtext>f</mml:mtext><mml:msup><mml:mtext>&#x2009;</mml:mtext><mml:mn>7</mml:mn></mml:msup></mml:math> configuration of the <mml:math id="E12" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mtext>Eu</mml:mtext><mml:mrow><mml:mn>2</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:math> ion. The <mml:math id="E13" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mtext>Nd</mml:mtext><mml:mrow><mml:mn>3</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:math> ion doping in the phosphor generates deep traps which result in long afterglow phosphorescence.

Hojin Ryu

K. S. Bartwal

Photoluminescent Spectra of Nd3+ Codoped CaAl2O4:Eu2+ Blue Phosphor

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Advances in Materials Science and Engineering publishes research in all areas of materials science and engineering, including the synthesis and properties of materials, and their applications in engineering applications.

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Advances in Materials Science and Engineering