printing-fabrication-bulk-heterojunction-solar-cells-situ-morphology

Printing Fabrication of Bulk Heterojunction Solar Cells and <em>In Situ</em> Morphology Characterization

Polymer-based materials hold promise as low-cost, flexible efficient photovoltaic devices. Most laboratory efforts to achieve high performance devices ...

Lawrence Berkeley National Laboratory

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The structure of human cortical bone evolves over multiple length scales from its basic constituents of collagen and hydroxyapatite at the nanoscale to osteonal structures at near-millimeter dimensions, which all provide the basis for its mechanical properties. To resist fracture, bone's toughness is derived intrinsically through plasticity (e.g., fibrillar sliding) at structural scales typically below a micrometer and extrinsically (i.e., during crack growth) through mechanisms (e.g., crack deflection/bridging) generated at larger structural scales. Biological factors such as aging lead to a markedly increased fracture risk, which is often associated with an age-related loss in bone mass (bone quantity). However, we find that age-related structural changes can significantly degrade the fracture resistance (bone quality) over multiple length scales. Using in situ small-angle X-ray scattering and wide-angle X-ray diffraction to characterize submicrometer structural changes and synchrotron X-ray computed tomography and in situ fracture-toughness measurements in the scanning electron microscope to characterize effects at micrometer scales, we show how these age-related structural changes at differing size scales degrade both the intrinsic and extrinsic toughness of bone. Specifically, we attribute the loss in toughness to increased nonenzymatic collagen cross-linking, which suppresses plasticity at nanoscale dimensions, and to an increased osteonal density, which limits the potency of crack-bridging mechanisms at micrometer scales. The link between these processes is that the increased stiffness of the cross-linked collagen requires energy to be absorbed by "plastic" deformation at higher structural levels, which occurs by the process of microcracking.

Age-related changes in the plasticity and toughness of human cortical bone at multiple length scales.

La structure de l&#39;os cortical humaine &eacute;volue sur plusieurs &eacute;chelles de longueur de ses constituants de base de collag&egrave;ne et d&#39;hydroxyapatite &agrave; l&#39;&eacute;chelle nanom&eacute;trique pour structures osteonal au millim&egrave;tre pr&egrave;s dimensions, qui tous servent de base pour ses propri&eacute;t&eacute;s m&eacute;caniques. Pour pouvoir r&eacute;sister &agrave; la rupture, la duret&eacute; de l&#39;OS est d&eacute;riv&eacute;e intrins&egrave;quement par plasticit&eacute; (p. ex., glissement fibrillaire) aux &eacute;chelles structurelles g&eacute;n&eacute;ralement au-dessous d&#39;un microm&egrave;tre et extrins&egrave;que (c&#39;est-&agrave;-dire, au cours de la craquelure) par le biais de m&eacute;canismes (p. ex., fente d&eacute;flexion/transition) g&eacute;n&eacute;r&eacute;es &agrave; plus grandes &eacute;chelles structurelles. Des facteurs biologiques comme le vieillissement conduisent &agrave; un risque nettement accru de fracture, qui est souvent associ&eacute; &agrave; une perte li&eacute;e &agrave; l&#39;&acirc;ge, la masse osseuse (quantit&eacute; de l&#39;OS). Toutefois, on constate que les changements structurels li&eacute;s &agrave; l&#39;&acirc;ge peuvent d&eacute;grader consid&eacute;rablement la r&eacute;sistance &agrave; la rupture (qualit&eacute; de l&#39;OS) sur plusieurs &eacute;chelles de longueur. L&#39;utilisation in situe diffusion de petits angles des rayons x et grand angle de diffraction des rayons x pour caract&eacute;riser les changements structurels SUBMICROMETRIQUES et synchrotron radiographie calcul&eacute; tomographie et mesures in situ de t&eacute;nacit&eacute; dans le microscope &eacute;lectronique &agrave; balayage pour caract&eacute;riser les effets &agrave; l&#39;&eacute;chelle du microm&egrave;tre, nous montrons comment ces changements structurels li&eacute;s &agrave; l&#39;&acirc;ge &agrave; diff&eacute;rentes &eacute;chelles de taille d&eacute;gradent les deux la r&eacute;sistance intrins&egrave;que et extrins&egrave;que d&#39;os. Plus pr&eacute;cis&eacute;ment, nous attribuons la perte de duret&eacute; &agrave; la r&eacute;ticulation de collag&egrave;ne non-enzymatique accrue, qui supprime la plasticit&eacute; aux dimensions nanom&eacute;triques et &agrave; une densit&eacute; d&#39;osteonal accrue, ce qui limite l&#39;action de fente-transition des m&eacute;canismes &agrave; l&#39;&eacute;chelle du microm&egrave;tre. Le lien entre ces processus, c&#39;est que la rigidit&eacute; accrue du collag&egrave;ne r&eacute;ticul&eacute; exige l&#39;&eacute;nergie absorb&eacute;e par la d&eacute;formation de &laquo; plastique &raquo; &agrave; un niveau structural sup&eacute;rieur, qui se produit par le proc&eacute;d&eacute; de microfissuration.

Age-related changes in la plasticit&eacute; et la duret&eacute; de l&#39;os cortical humaine longuement plusieurs &eacute;chelles.

La struttura dell&#39;osso corticale umano si evolve su scale di lunghezza pi&ugrave; dai suoi costituenti fondamentali del collagene e idrossiapatite nanometrica alle strutture osteonale a dimensioni nei pressi di millimetro, che tutti forniscono la base per le sue propriet&agrave; meccaniche. Per resistere alla frattura, tenacit&agrave; dell&#39;osso &egrave; derivato intrinsecamente attraverso la plasticit&agrave; (ad es., fibrillare scorrevole) a scale strutturali in genere inferiore a un micrometro ed estrinsecamente (cio&egrave;, durante la crescita crack) attraverso meccanismi (ad es., crack deflessione/bridging) generati a grandi scale strutturali. Fattori biologici quali l&#39;invecchiamento portano ad un rischio di frattura marcatamente aumentata, che &egrave; spesso associato a un&#39;et&agrave;-correlate perdita nella massa ossea (quantit&agrave; di osso). Tuttavia, abbiamo trovato che cambiamenti strutturali legati all&#39;et&agrave; possono degradare significativamente la resistenza di frattura (qualit&agrave; ossea) sopra scale multiple di lunghezza. Utilizzando la dispersione di raggi x small-angle in situ e diffrazione dei raggi x grandangolare per caratterizzare submicrometriche cambiamenti strutturali e sincrotrone a raggi x computato tomografia e misure in situ di tenacit&agrave; alla frattura nel microscopio elettronico a scansione per caratterizzare gli effetti a micrometro scale, ci mostrano come questi cambiamenti strutturali legati all&#39;et&agrave;, a differenti scale di dimensioni degradano la durezza intrinseca ed estrinseca dell&#39;osso. In particolare, attribuire la perdita di tenacit&agrave; a cross-linking del collagene nonenzymatic maggiore, che sopprime la plasticit&agrave; a dimensioni nanometriche e a una densit&agrave; maggiore osteonale, che limita la potenza dei meccanismi di crack-bridging a scale di micrometro. Il collegamento fra questi processi &egrave; che la maggiore rigidit&agrave; del collagene reticolata richiede energia per essere assorbita dalla deformazione di &quot;plastica&quot; a livelli pi&ugrave; alti strutturali, che avviene tramite il processo di microcracking.

Scale di cambiamenti legati all&#39;et&agrave; la plasticit&agrave; e la costituzione dell&#39;osso corticale umano pi&ugrave; a lungo.

&#x30D2;&#x30C8;&#x306E;&#x76AE;&#x8CEA;&#x9AA8;&#x306E;&#x69CB;&#x9020;&#x306F;&#x967D;&#x6027;&#x69CB;&#x9020;&#x3067;&#x306F;&#x3001;&#x3059;&#x3079;&#x3066;&#x306E;&#x6839;&#x62E0;&#x3068;&#x305D;&#x306E;&#x6A5F;&#x68B0;&#x7684;&#x7279;&#x6027;&#x30DF;&#x30EA;&#x6CE2;&#x8FD1;&#x304F;&#x5BF8;&#x6CD5;&#x306B;&#x30B3;&#x30E9;&#x30FC;&#x30B2;&#x30F3;&#x3068;&#x6C34;&#x9178;&#x30A2;&#x30D1;&#x30BF;&#x30A4;&#x30C8;&#x3092;&#x30CA;&#x30CE;&#x30B9;&#x30B1;&#x30FC;&#x30EB;&#x3067;&#x305D;&#x306E;&#x57FA;&#x790E;&#x7684;&#x306A;&#x6210;&#x5206;&#x304B;&#x3089;&#x8907;&#x6570;&#x306E;&#x9577;&#x3055;&#x30B9;&#x30B1;&#x30FC;&#x30EB;&#x3067;&#x9032;&#x5316;&#x3057;&#x307E;&#x3059;&#x3002;&#x9AA8;&#x6298;&#x306B;&#x62B5;&#x6297;&#x3059;&#x308B;&#x306B;&#x306F;&#x3001;&#x9AA8;&#x306E;&#x976D;&#x6027;&#x672C;&#x8CEA;&#x7684;&#x306B; &#xFF08;&#x4F8B;&#x3048;&#x3070;&#x3001;&#x3059;&#x3079;&#x308A;&#x7DDA;&#x7DAD;&#xFF09; &#x5851;&#x6027;&#x69CB;&#x9020;&#x30B9;&#x30B1;&#x30FC;&#x30EB;&#x3067;&#x901A;&#x5E38;&#x30DE;&#x30A4;&#x30AF;&#x30ED; &#x30E1;&#x30FC;&#x30C8;&#x30EB;&#x4EE5;&#x4E0B;&#x3068;&#x30DC;&#x30FC;&#x30AB;&#x30EB;&#x3092; (&#x3059;&#x306A;&#x308F;&#x3061;&#x4E2D;&#x306E;&#x304D;&#x88C2;) &#x3088;&#x308A;&#x5927;&#x304D;&#x3044;&#x30B9;&#x30B1;&#x30FC;&#x30EB;&#x69CB;&#x9020;&#x306E;&#x751F;&#x6210;&#x30E1;&#x30AB;&#x30CB;&#x30BA;&#x30E0; (&#x4F8B;&#x3048;&#x3070;&#x3001;&#x30AF;&#x30E9;&#x30C3;&#x30AF;&#x504F;&#x5411;/&#x30D6;&#x30EA;&#x30C3;&#x30B8;) &#x3092;&#x6D3E;&#x751F;&#x3057;&#x307E;&#x3059;&#x3002;&#x9AD8;&#x9F62;&#x5316;&#x306A;&#x3069;&#x306E;&#x751F;&#x7269;&#x5B66;&#x7684;&#x8981;&#x56E0;&#x306F;&#x3001;&#x3057;&#x3070;&#x3057;&#x3070;&#x9AA8; &#xFF08;&#x9AA8;&#x91CF;) &#x306E;&#x52A0;&#x9F62;&#x306B;&#x4F34;&#x3046;&#x640D;&#x5931;&#x306B;&#x95A2;&#x9023;&#x4ED8;&#x3051;&#x3089;&#x308C;&#x3066;&#x3044;&#x308B;&#x3001;&#x8457;&#x3057;&#x304F;&#x5897;&#x52A0;&#x3059;&#x308B;&#x9AA8;&#x6298;&#x306E;&#x5371;&#x967A;&#x6027;&#x306B; &#x3057;&#x307E;&#x3059;&#x3002;&#x3057;&#x304B;&#x3057;&#x3001;&#x69CB;&#x9020;&#x5909;&#x5316;&#x304C;&#x5927;&#x5E45;&#x306B;&#x8907;&#x6570;&#x306E;&#x9577;&#x3055;&#x30B9;&#x30B1;&#x30FC;&#x30EB;&#x3067;&#x8010;&#x6B20;&#x640D;&#x6027; &#xFF08;&#x9AA8;&#x306E;&#x8CEA;&#xFF09; &#x3092;&#x52A3;&#x5316;&#x3055;&#x305B;&#x308B;&#x3053;&#x3068;&#x3092;&#x898B;&#x3064;&#x3051;&#x307E;&#x3059;&#x3002;In-situ &#x5FAE;&#x5C0F;&#x89D2; x &#x7DDA;&#x6563;&#x4E71;&#x3068;&#x5E83;&#x89D2; x &#x7DDA;&#x56DE;&#x6298;&#x30B5;&#x30D6;&#x30DF;&#x30AF;&#x30ED;&#x30F3;&#x69CB;&#x9020;&#x5909;&#x5316;&#x3068;&#x653E;&#x5C04;&#x5149; x &#x7DDA;&#x306E;&#x7279;&#x5FB4;&#x3092;&#x4F7F;&#x7528;&#x3057;&#x3066;&#x8A08;&#x7B97;&#x30C8;&#x30E2;&#x30B0;&#x30E9;&#x30D5;&#x30A3;&#x30FC;&#x3068;&#x305D;&#x306E;&#x5834;&#x306E;&#x7834;&#x58CA;&#x976D;&#x6027;&#x6E2C;&#x5B9A;&#x30DE;&#x30A4;&#x30AF;&#x30ED; &#x30E1;&#x30FC;&#x30C8;&#x30EB; &#x30B9;&#x30B1;&#x30FC;&#x30EB;&#x306E;&#x52B9;&#x679C;&#x3092;&#x96FB;&#x5B50;&#x9855;&#x5FAE;&#x93E1;&#x3067;&#x3001;&#x79C1;&#x9054;&#x306F;&#x3069;&#x306E;&#x3088;&#x3046;&#x306B;&#x3053;&#x308C;&#x3089;&#x306E;&#x5E74;&#x9F62;&#x95A2;&#x9023;&#x306E;&#x69CB;&#x9020;&#x5909;&#x5316;&#x7570;&#x306A;&#x308B;&#x30B5;&#x30A4;&#x30BA;&#x306E;&#x30B9;&#x30B1;&#x30FC;&#x30EB;&#x3067;&#x7D44;&#x307F;&#x8FBC;&#x307F;&#x3068;&#x5916;&#x56E0;&#x6027;&#x976D;&#x6027;&#x9AA8;&#x306E;&#x4F4E;&#x4E0B;&#x3092;&#x793A;&#x3057;&#x307E;&#x3059;&#x3002;&#x5177;&#x4F53;&#x7684;&#x306B;&#x306F;&#x3001;&#x6211;&#x3005; &#x306F;&#x30CA;&#x30CE;&#x30B9;&#x30B1;&#x30FC;&#x30EB;&#x6B21;&#x5143;&#x3067;&#x3001;&#x4E80;&#x88C2;&#x3092;&#x57CB;&#x3081;&#x308B;&#x30E1;&#x30AB;&#x30CB;&#x30BA;&#x30E0; &#x30DE;&#x30A4;&#x30AF;&#x30ED;&#x30E1;&#x30FC;&#x30BF; &#x30B9;&#x30B1;&#x30FC;&#x30EB;&#x3067;&#x306E;&#x52B9;&#x529B;&#x306E;&#x5236;&#x9650;&#x3092;&#x5897;&#x52A0;&#x306E;&#x8A08;&#x6E2C;&#x5BC6;&#x5EA6;&#x306E;&#x53EF;&#x5851;&#x6027;&#x3092;&#x6291;&#x5236;&#x3059;&#x308B;&#x640D;&#x5931;&#x3092;&#x5897;&#x52A0;&#x975E;&#x9175;&#x7D20;&#x7684;&#x30B3;&#x30E9;&#x30FC;&#x30B2;&#x30F3;&#x67B6;&#x6A4B;&#x3001;&#x9AD8;&#x976D;&#x6027;&#x5316;&#x5C5E;&#x6027;&#x3057;&#x307E;&#x3059;&#x3002;&#x3053;&#x308C;&#x3089;&#x306E;&#x30D7;&#x30ED;&#x30BB;&#x30B9;&#x306E;&#x9593;&#x306E;&#x30EA;&#x30F3;&#x30AF;&#x306F;&#x3001;&#x67B6;&#x6A4B;&#x30B3;&#x30E9;&#x30FC;&#x30B2;&#x30F3;&#x306E;&#x5897;&#x52A0;&#x525B;&#x6027;&#x30DE;&#x30A4;&#x30AF;&#x30ED;&#x30AF; &#x30E9;&#x30C3;&#x30AF;&#x767A;&#x751F;&#x306E;&#x904E;&#x7A0B;&#x3067;&#x767A;&#x751F;&#x3059;&#x308B;&#x300C;&#x30D7;&#x30E9;&#x30B9;&#x30C1;&#x30C3;&#x30AF;&#x300D;&#x5909;&#x5F62;&#x30EC;&#x30D9;&#x30EB;&#x306E;&#x9AD8;&#x3044;&#x69CB;&#x9020;&#x3001;&#x306B;&#x3088;&#x3063;&#x3066;&#x5438;&#x53CE;&#x3055;&#x308C;&#x308B;&#x30A8;&#x30CD;&#x30EB;&#x30AE;&#x30FC;&#x304C;&#x5FC5;&#x8981;&#x3067;&#x3059;&#x3002;

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&#xC5EC;&#xB7EC; &#xAE38;&#xC774; &#xBE44;&#xB298; &#xCF5C;&#xB77C;&#xAC90;&#xACFC; hydroxyapatite&#xB97C; &#xB098;&#xB178;&#xC5D0;&#xC11C;&#xC758; &#xAE30;&#xBCF8;&#xC801;&#xC778; &#xC131;&#xBD84;&#xC758;&#xC5D0;&#xC11C; &#xADFC;&#xCC98; &#xBC00;&#xB9AC;&#xBBF8;&#xD130; &#xD06C;&#xAE30;&#xC758; &#xAE30;&#xACC4;&#xC801; &#xD2B9;&#xC131;&#xC5D0; &#xB300; &#xD55C; &#xAE30;&#xCD08;&#xB97C; &#xC81C;&#xACF5; &#xD558;&#xB294; &#xBAA8;&#xB4E0;&#xC5D0;&#xC11C; osteonal &#xAD6C;&#xC870;&#xB97C; &#xD1B5;&#xD574; &#xC778;&#xAC04;&#xC758; &#xB300;&#xB1CC; &#xD53C; &#xC9C8; &#xACE8;&#xC758; &#xAD6C;&#xC870; &#xC9C4;&#xD654;. &#xACE8;&#xC808;&#xC5D0; &#xC800;&#xD56D;, &#xBF08;&#xC758; &#xC778; &#xC131; &#xD30C;&#xC0DD; &#xB429;&#xB2C8;&#xB2E4; &#xBCF8;&#xC9C8;&#xC801;&#xC73C;&#xB85C; &#xC77C;&#xBC18;&#xC801;&#xC73C;&#xB85C; &#xB9C8;&#xC774;&#xD06C;&#xB85C; &#xBBF8;&#xD130; &#xC544;&#xB798; &#xACE0; extrinsically &#xAD6C;&#xC870; &#xC2A4;&#xCF00;&#xC77C;&#xC5D0;&#xC11C; (&#xC608;&#xB97C; &#xB4E4;&#xC5B4;, fibrillar &#xC2AC;&#xB77C;&#xC774;&#xB529;) &#xC18C;&#xC131;&#xC744; &#xD1B5;&#xD574; (&#xC989;, &#xB3D9;&#xC548; &#xADE0;&#xC5F4; &#xC131;&#xC7A5;) &#xBA54;&#xCEE4;&#xB2C8;&#xC998; (&#xC608;: &#xADE0;&#xC5F4; &#xD3B8;&#xD5A5;/&#xBE0C;&#xB9AC;&#xC9C0;) &#xB354; &#xD070; &#xAD6C;&#xC870;&#xC801; &#xC2A4;&#xCF00;&#xC77C;&#xC5D0;&#xC11C; &#xC0DD;&#xC131; &#xB41C;&#xC744; &#xD1B5;&#xD574;. &#xB178;&#xD654; &#xB4F1;&#xC758; &#xC0DD;&#xBB3C;&#xD559;&#xC801; &#xC694;&#xC18C;&#xB294; &#xC885;&#xC885; &#xC5F0;&#xAD00; &#xB41C; &#xBF08; &#xC9C8;&#xB7C9; (&#xBF08; &#xC218;&#xB7C9;) &#xB098;&#xC774; &#xAD00;&#xB828; &#xB41C; &#xC190;&#xC2E4;&#xACFC; &#xD604;&#xC800; &#xD558; &#xAC8C; &#xC99D;&#xAC00; &#xACE8;&#xC808; &#xC704;&#xD5D8;&#xC73C;&#xB85C; &#xC774;&#xC5B4;&#xC9C8;. &#xADF8;&#xB7EC;&#xB098;, &#xC6B0;&#xB9AC;&#xB294; &#xAD6C;&#xC870;&#xC801;&#xC778; &#xBCC0;&#xD654; &#xB098;&#xC774; &#xAD00;&#xB828; &#xB41C; &#xC5EC;&#xB7EC; &#xAE38;&#xC774;&#xC758; &#xBE44;&#xB298;&#xC744; &#xD1B5;&#xD574; &#xBD84;&#xC1C4; &#xC800;&#xD56D; (&#xBF08; &#xC9C8;)&#xB97C; &#xC800;&#xD558; &#xD06C;&#xAC8C; &#xC218; &#xCC3E;&#xC73C;&#xC2ED;&#xC2DC;&#xC624;. &#xB2E8;&#xCE35; &#xCD2C;&#xC601; &#xBC0F; &#xD604;&#xC7A5;&#xC5D0;&#xC11C; &#xD30C;&#xAD34; &#xC778; &#xC131; &#xCE21;&#xC815; &#xB9C8;&#xC774;&#xD06C;&#xB85C;&#xBBF8;&#xD130; &#xC2A4;&#xCF00;&#xC77C;&#xC5D0;&#xC11C; &#xD6A8;&#xACFC; &#xD2B9;&#xC131;&#xC744; &#xC2A4;&#xCE90;&#xB2DD; &#xC804;&#xC790; &#xD604;&#xBBF8;&#xACBD;&#xC5D0;&#xC11C; &#xACC4;&#xC0B0; &#xB41C; submicrometer &#xAD6C;&#xC870; &#xBCC0;&#xD654;&#xC640; synchrotron X-ray&#xC758; &#xD2B9;&#xC131;&#xC744; &#xD604;&#xC7A5;&#xC5D0;&#xC11C; &#xC791;&#xC740; &#xAC01;&#xB3C4; x-&#xC120; &#xC0B0;&#xB780; &#xBC0F; &#xAD11;&#xAC01; x-&#xC120; &#xD68C;&#xC808;&#xC744; &#xC0AC;&#xC6A9; &#xD558; &#xC5EC;, &#xC6B0;&#xB9AC;&#xAC00; &#xC5B4;&#xB5BB;&#xAC8C; &#xB2E4;&#xB978; &#xD06C;&#xAE30; &#xC2A4;&#xCF00;&#xC77C;&#xC5D0;&#xC11C; &#xB098;&#xC774; &#xAD00;&#xB828; &#xAD6C;&#xC870; &#xBCC0;&#xACBD; &#xC774;&#xB7EC;&#xD55C; &#xBF08;&#xC758; &#xB0B4;&#xBD80;&#xC640; &#xC678;&#xBD80; &#xC131; &#xC800;&#xD558;. &#xD2B9;&#xD788;, &#xC6B0;&#xB9AC;&#xB294; &#xC18C;&#xC131; &#xB098;&#xB178; &#xD06C;&#xAE30;&#xC5D0;&#xC11C; &#xBC0F; &#xB9C8;&#xC774;&#xD06C;&#xB85C;&#xBBF8;&#xD130; &#xC2A4;&#xCF00;&#xC77C;&#xC5D0;&#xC11C; &#xADE0;&#xC5F4; &#xBE0C;&#xB9AC;&#xC9D5; &#xBA54;&#xCEE4;&#xB2C8;&#xC998;&#xC758; &#xD798;&#xC744; &#xC81C;&#xD55C; &#xD558;&#xB294; &#xC99D;&#xAC00; osteonal &#xBC00;&#xB3C4;&#xB97C; &#xC5B5;&#xC81C; &#xD558;&#xB294; &#xC778; &#xC131; &#xC99D;&#xAC00; nonenzymatic &#xCF5C;&#xB77C;&#xAC90; &#xAD50;&#xCC28;&#xC5D0; &#xC190;&#xC2E4;&#xC744; &#xC18D;&#xC131;. &#xC774;&#xB7EC;&#xD55C; &#xD504;&#xB85C;&#xC138;&#xC2A4; &#xAC04;&#xC758; &#xC5F0;&#xACB0;&#xC774; &#xBCF5;&#xC0AC;&#xD574;&#xC62C;&#xB41C; &#xCF5C;&#xB77C;&#xAC90; &#xC99D;&#xAC00; &#xAC15;&#xC131; microcracking &#xACFC;&#xC815;&#xC5D0; &#xC758;&#xD574; &#xBC1C;&#xC0DD; &#xD558;&#xB294; &#xC0C1;&#xBD80; &#xAD6C;&#xC870;&#xC5D0;&#xC11C; &quot;&#xD50C;&#xB77C;&#xC2A4;&#xD2F1;&quot; &#xBCC0;&#xD615;&#xC5D0; &#xC758;&#xD574; &#xD761;&#xC218;&#xC5D0; &#xC5D0;&#xB108;&#xC9C0;&#xB97C; &#xD544;&#xC694;&#xB85C; &#xD569;&#xB2C8;&#xB2E4;.

&#xC18C;&#xC131; &#xBC0F; &#xC5EC;&#xB7EC; &#xAE38;&#xC774; &#xC778;&#xAC04;&#xC758; &#xB300;&#xB1CC; &#xD53C; &#xC9C8; &#xACE8;&#xC758; &#xC778; &#xC131; &#xBCC0;&#xD654; &#xB098;&#xC774; &#xAD00;&#xB828; &#xD655;&#xC7A5; &#xB429;&#xB2C8;&#xB2E4;.

La estructura del hueso cortical humano evoluciona a m&uacute;ltiples escalas de longitud de sus constituyentes b&aacute;sicos del col&aacute;geno y de hidroxiapatita en la nanoescala a estructuras osteonal en dimensiones cerca de mil&iacute;metros, que proporcionan la base para sus propiedades mec&aacute;nicas. Para resistir la fractura, dureza del hueso se deriva intr&iacute;nsecamente a trav&eacute;s de la plasticidad (por ejemplo, el desplazamiento fibrilar) a escalas estructurales t&iacute;picamente por debajo de un micr&oacute;metro y extr&iacute;nseco (es decir, durante el crecimiento de las grietas) a trav&eacute;s de mecanismos (por ejemplo, crack desviaci&oacute;n/puente) generados en escalas m&aacute;s grandes estructurales. Factores biol&oacute;gicos tales como envejecimiento llevan a un riesgo de fractura marcado creciente, que a menudo se asocia con una p&eacute;rdida relacionada con la edad en la masa &oacute;sea (cantidad de hueso). Sin embargo, encontramos que los cambios estructurales relacionadas con la edad pueden degradar significativamente la resistencia de la fractura (hueso calidad) a m&uacute;ltiples escalas de longitud. Usando dispersi&oacute;n de rayos-x de &aacute;ngulo peque&ntilde;o in situ y difracci&oacute;n de rayos x gran angular para caracterizar los cambios estructurales Submicrom&eacute;trica y rayos x de sincrotr&oacute;n tomograf&iacute;a computada y mediciones in situ-resistencia a la fractura en el microscopio electr&oacute;nico de barrido para caracterizar los efectos en escalas de micr&oacute;metro, mostramos c&oacute;mo estos cambios estructurales relacionadas con la edad a diferentes escalas de tama&ntilde;o degradar&aacute;n la dureza intr&iacute;nseca y extr&iacute;nseca del hueso. Espec&iacute;ficamente, atribuimos la p&eacute;rdida en dureza a mayor no enzim&aacute;ticos col&aacute;geno Cross-linking, que suprime la plasticidad en dimensiones de nanoescala y a una densidad de osteonal creciente, que limita la potencia de los mecanismos grieta-enlace en escalas de Micr&oacute;metro. La vinculaci&oacute;n de estos procesos es que el aumento de la rigidez del col&aacute;geno reticulado requiere energ&iacute;a sea absorbida por la deformaci&oacute;n de &quot;pl&aacute;stico&quot; en niveles estructurales, que se produce por el proceso de microcracking.

Cambios relacionados con la edad en la plasticidad y la dureza del hueso cortical humano largamente m&uacute;ltiples escalas.

Bone comprises a complex structure of primarily collagen, hydroxyapatite and water, where each hierarchical structural level contributes to its strength, ductility and toughness. These properties, however, are degraded by irradiation, arising from medical therapy or bone-allograft sterilization. We provide here a mechanistic framework for how irradiation affects the nature and properties of human cortical bone over a range of characteristic (nano to macro) length-scales, following x-ray exposures up to 630 kGy. Macroscopically, bone strength, ductility and fracture resistance are seen to be progressively degraded with increasing irradiation levels. At the micron-scale, fracture properties, evaluated using insitu scanning electron microscopy and synchrotron x-ray computed micro-tomography, provide mechanistic information on how cracks interact with the bone-matrix structure. At sub-micron scales, strength properties are evaluated with insitu tensile tests in the synchrotron using small-/wide-angle x-ray scattering/diffraction, where strains are simultaneously measured in the macroscopic tissue, collagen fibrils and mineral. Compared to healthy bone, results show that the fibrillar strain is decreased by ∼40% following 70 kGy exposures, consistent with significant stiffening and degradation of the collagen. We attribute the irradiation-induced deterioration in mechanical properties to mechanisms at multiple length-scales, including changes in crack paths at micron-scales, loss of plasticity from suppressed fibrillar sliding at sub-micron scales, and the loss and damage of collagen at the nano-scales, the latter being assessed using Raman and Fourier Transform Infrared spectroscopy and a fluorometric assay.

Characterization of the effects of x-ray irradiation on the hierarchical structure and mechanical properties of human cortical bone.

Metal chalcogenides are important materials for a myriad of devices, but the ability to control their porosity is lacking. We report a method of inducing hierarchically ordered porosity using surface-treated nanocrystals and complementary architecture-directing agents. The resulting mesoporous materials are robust to thermal annealing and chemical transformations.

Evolution of ordered metal chalcogenide architectures through chemical transformations.

Arapaima gigas, a fresh water fish found in the Amazon Basin, resist predation by piranhas through the strength and toughness of their scales, which act as natural dermal armour. Arapaima scales consist of a hard, mineralized outer shell surrounding a more ductile core. This core region is composed of aligned mineralized collagen fibrils arranged in distinct lamellae. Here we show how the Bouligand-type (twisted plywood) arrangement of collagen fibril lamellae has a key role in developing their unique protective properties, by using in situ synchrotron small-angle X-ray scattering during mechanical tensile tests to observe deformation mechanisms in the fibrils. Specifically, the Bouligand-type structure allows the lamellae to reorient in response to the loading environment; remarkably, most lamellae reorient towards the tensile axis and deform in tension through stretching/sliding mechanisms, whereas other lamellae sympathetically rotate away from the tensile axis and compress, thereby enhancing the scale's ductility and toughness to prevent fracture.

Mechanical adaptability of the Bouligand-type structure in natural dermal armour.

While most fracture-mechanics investigations on bone have been performed at low strain rates, physiological fractures invariably occur at higher loading rates. Here, at strain rates from 10(-5) to 10(-1) s(-1), we investigate deformation and fracture in bone at small length-scales using in situ small-angle x-ray scattering (SAXS) to study deformation in the mineralized collagen fibrils and at the microstructural level via fracture-mechanics experiments to study toughening mechanisms generating toughness through crack-tip shielding. Our results show diminished bone toughness at increasing strain rates as cracks penetrate through the osteons at higher strain rates instead of deflecting at the cement lines, which is a prime toughening mechanism in bone at low strain rates. The absence of crack deflection mechanisms at higher strain rates is consistent with lower intrinsic bone matrix toughness. In the SAXS experiments, higher fibrillar strains at higher strain rates suggest less inelastic deformation and thus support a lower intrinsic toughness. The increased incidence of fracture induced by high strain rates can be associated with a loss in toughness in the matrix caused by a strain rate induced stiffening of the fibril ductility, i.e., a "locking-up" of the viscous sliding and sacrificial bonding mechanisms, which are the origin of inelastic deformation (and toughness) in bone at small length-scales.

Fracture resistance of human cortical bone across multiple length-scales at physiological strain rates.

The scales of the arapaima (Arapaima gigas), one of the largest freshwater fish in the world, can serve as inspiration for the design of flexible dermal armor. Each scale is composed of two layers: a laminate composite of parallel collagen fibrils and a hard, highly mineralized surface layer. We review the structure of the arapaima scales and examine the functions of the different layers, focusing on the mechanical behavior, including tension and penetration of the scales, with and without the highly mineralized outer layer. We show that the fracture of the mineral and the stretching, rotation and delamination of collagen fibrils dissipate a significant amount of energy prior to catastrophic failure, providing high toughness and resistance to penetration by predator teeth. We show that the arapaima's scale has evolved to minimize damage from penetration by predator teeth through a Bouligand-like arrangement of successive layers, each consisting of parallel collagen fibrils with different orientations. This inhibits crack propagation and restricts damage to an area adjoining the penetration. The flexibility of the lamellae is instrumental to the redistribution of the compressive stresses in the underlying tissue, decreasing the severity of the concentrated load produced by the action of a tooth. The experimental results, combined with small-angle X-ray scattering characterization and molecular dynamics simulations, provide a complete picture of the mechanisms of deformation, delamination and rotation of the lamellae during tensile extension of the scale.

Protective role of Arapaima gigas fish scales: structure and mechanical behavior.

Anti-resorptive and anabolic agents are often prescribed for the treatment of osteoporosis continuously or sequentially for many years. However their impact on cortical bone quality and bone strength is not clear.

Effect of sequential treatments with alendronate, parathyroid hormone (1-34) and raloxifene on cortical bone mass and strength in ovariectomized rats.

The mini-slot-die coater offers a simple, convenient, materials-efficient route to print bulk-heterojunction (BHJ) organic photovoltaics (OPVs) that show efficiencies similar to spin-coating. Grazing-incidence X-ray diffraction (GIXD) and GI small-angle X-ray scattering (GISAXS) methods are used in real time to characterize the active-layer formation during printing. A polymer-aggregation-phase-separation-crystallization mechanism for the evolution of the morphology describes the observations.

Fast printing and in situ morphology observation of organic photovoltaics using slot-die coating.

Tear resistance is of vital importance in the various functions of skin, especially protection from predatorial attack. Here, we mechanistically quantify the extreme tear resistance of skin and identify the underlying structural features, which lead to its sophisticated failure mechanisms. We explain why it is virtually impossible to propagate a tear in rabbit skin, chosen as a model material for the dermis of vertebrates. We express the deformation in terms of four mechanisms of collagen fibril activity in skin under tensile loading that virtually eliminate the possibility of tearing in pre-notched samples: fibril straightening, fibril reorientation towards the tensile direction, elastic stretching and interfibrillar sliding, all of which contribute to the redistribution of the stresses at the notch tip.

On the tear resistance of skin.

Bisphosphonates are widely used to treat osteoporosis, but have been associated with atypical femoral fractures (AFFs) in the long term, which raises a critical health problem for the aging population. Several clinical studies have suggested that the occurrence of AFFs may be related to the bisphosphonate-induced changes of bone turnover, but large discrepancies in the results of these studies indicate that the salient mechanisms responsible for any loss in fracture resistance are still unclear. Here the role of bisphosphonates is examined in terms of the potential deterioration in fracture resistance resulting from both intrinsic (plasticity) and extrinsic (shielding) toughening mechanisms, which operate over a wide range of length-scales. Specifically, we compare the mechanical properties of two groups of humeri from healthy beagles, one control group comprising eight females (oral doses of saline vehicle, 1 mL/kg/day, 3 years) and one treated group comprising nine females (oral doses of alendronate used to treat osteoporosis, 0.2mg/kg/day, 3 years). Our data demonstrate treatment-specific reorganization of bone tissue identified at multiple length-scales mainly through advanced synchrotron x-ray experiments. We confirm that bisphosphonate treatments can increase non-enzymatic collagen cross-linking at molecular scales, which critically restricts plasticity associated with fibrillar sliding, and hence intrinsic toughening, at nanoscales. We also observe changes in the intracortical architecture of treated bone at microscales, with partial filling of the Haversian canals and reduction of osteon number. We hypothesize that the reduced plasticity associated with BP treatments may induce an increase in microcrack accumulation and growth under cyclic daily loadings, and potentially increase the susceptibility of cortical bone to atypical (fatigue-like) fractures.

Alendronate treatment alters bone tissues at multiple structural levels in healthy canine cortical bone.

Assembly of presynthesized nanocrystals by block copolymer micelles can be rationalized by the incorporation of nanocrystals into micellar coronas of constant width. As determined by quantitative analysis using small-angle X-ray scattering, high loading of small nanocrystals yields composites exhibiting order on two length scales, whereas intermediate loading of nanocrystals larger than the coronal width produces single nanocrystal networks. The resulting structures obey expectations of thermodynamically driven assembly on the nanocrystal length scale, whereas kinetically frozen packing principles dictate order on the polymer micelle length scale.

Ordering in Polymer Micelle-Directed Assemblies of Colloidal Nanocrystals.

Bisphosphonates are a common treatment to reduce osteoporotic fractures. This treatment induces osseous structural and compositional changes accompanied by positive effects on osteoblasts and osteocytes. Here, we test the hypothesis that restored osseous cell behavior, which resembles characteristics of younger, healthy cortical bone, leads to improved bone quality. Microarchitecture and mechanical properties of young, treatment-naïve osteoporosis, and bisphosphonate-treated cases were investigated in femoral cortices. Tissue strength was measured using three-point bending. Collagen fibril-level deformation was assessed in non-traumatic and traumatic fracture states using synchrotron small-angle x-ray scattering (SAXS) at low and high strain rates. The lower modulus, strength and fibril deformation measured at low strain rates reflects susceptibility for osteoporotic low-energy fragility fractures. Independent of age, disease and treatment status, SAXS revealed reduced fibril plasticity at high strain rates, characteristic of traumatic fracture. The significantly reduced mechanical integrity in osteoporosis may originate from porosity and alterations to the intra/extrafibrillar structure, while the fibril deformation under treatment indicates improved nano-scale characteristics. In conclusion, losses in strength and fibril deformation at low strain rates correlate with the occurrence of fragility fractures in osteoporosis, while improvements in structural and mechanical properties following bisphosphonate treatment may foster resistance to fracture during physiological strain rates.

Intrinsic mechanical behavior of femoral cortical bone in young, osteoporotic and bisphosphonate-treated individuals in low- and high energy fracture conditions.

Eric Schaible

Advanced Light Source

Lawrence Berkeley National Laboratory

Printing Fabrication of Bulk Heterojunction Solar Cells and In Situ Morphology Characterization

Eric Schaible

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Lawrence Berkeley National Laboratory

Printing Fabrication of Bulk Heterojunction Solar Cells and In Situ Morphology Characterization

Advanced Light Source