@article{zhang_kostorz_liu_rigsbee_suryanarayana_wang_zhu_zhang_2008, title={Mechanical Behavior of Nanostructured Materials, in Honor of Carl Koch held at TMS 2007, Orlando, Florida Preface}, volume={493}, ISSN={["0921-5093"]}, DOI={10.1016/j.msea.2008.01.019}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Zhang, Xinghang and Kostorz, Gernot and Liu, Chain T. and Rigsbee, Mike and Suryanarayana, C. and Wang, Haiyan and Zhu, Yuntian and Zhang, Deliang}, year={2008}, month={Oct}, pages={1–2} }
 @article{narayan_bhaduri_fischman_rigsbee_zhang_2007, title={Next generation biomaterials - Preface}, volume={27}, ISSN={["0928-4931"]}, DOI={10.1016/j.msec.2006.05.022}, number={3}, journal={MATERIALS SCIENCE & ENGINEERING C-BIOMIMETIC AND SUPRAMOLECULAR SYSTEMS}, author={Narayan, Roger J. and Bhaduri, Sarit B. and Fischman, Gary and Rigsbee, J. Michael and Zhang, Xinghang}, year={2007}, month={Apr}, pages={345–346} }
 @article{wang_gupta_tiwari_zhang_narayan_2004, title={TaN-TiN binary alloys and superlattices as diffusion barriers for copper interconnections}, volume={33}, ISSN={0361-5235 1543-186X}, url={http://dx.doi.org/10.1007/S11664-004-0300-X}, DOI={10.1007/s11664-004-0300-x}, number={1}, journal={Journal of Electronic Materials}, publisher={Springer Science and Business Media LLC}, author={Wang, H. and Gupta, A. and Tiwari, Ashutosh and Zhang, X. and Narayan, J.}, year={2004}, month={Jan}, pages={L5–L5} }
 @article{wang_zhang_gupta_tiwari_narayan_2003, title={Growth and characteristics of TaN/TiN superlattice structures}, volume={83}, ISSN={["0003-6951"]}, DOI={10.1063/1.1616656}, abstractNote={Epitaxial B1 NaCl-structured TaN(3 nm)/TiN(2 nm) superlattice structures were grown on Si(100) substrates with a TiN buffer layer, using pulsed-laser deposition. A special target assembly was used to manipulate the thickness of each layer. X-ray diffraction, transmission electron microscopy, and scanning transmission electron microscopy (Z contrast) studies confirmed the single-crystalline nature of the superlattice with a uniform layer structure. Nanoindentation results suggest the high hardness of these superlattice structures. Four-point-probe resistivity measurements show low resistivity of the heterostructures and a Cu diffusion characteristic study proved this superlattice system can be a promising diffusion barrier and can withstand 700 °C annealing for 30 min.}, number={15}, journal={APPLIED PHYSICS LETTERS}, author={Wang, H and Zhang, X and Gupta, A and Tiwari, A and Narayan, J}, year={2003}, month={Oct}, pages={3072–3074} }
 @article{wang_gupta_tiwari_zhang_narayan_2003, title={TaN-TiN binary alloys and superlattices as diffusion barriers for copper interconnects}, volume={32}, ISSN={["0361-5235"]}, DOI={10.1007/s11664-003-0081-7}, number={10}, journal={JOURNAL OF ELECTRONIC MATERIALS}, author={Wang, H and Gupta, A and Tiwari, A and Zhang, X and Narayan, J}, year={2003}, month={Oct}, pages={994–999} }
 @article{wang_tiwari_zhang_kvit_narayan_2002, title={Copper diffusion characteristics in single-crystal and polycrystalline TaN}, volume={81}, ISSN={["0003-6951"]}, DOI={10.1063/1.1502193}, abstractNote={We have investigated the diffusivity of copper in single-crystal (NaCl-structured) and polycrystalline TaN thin films grown by pulsed-laser deposition. Polycrystalline TaN films were grown directly on Si(100), while single-crystal films were grown with TiN buffer layers. Both poly- and single-crystal films with Cu overlayers were annealed at 500, 600, 650, and 700 °C in vacuum to study the copper diffusion characteristics. The diffusion of copper into TaN was studied using scanning transmission electron microscopy (STEM) Z contrast, where the contrast is proportional to Z2 (atomic number), and TEM. The diffusion distances (2Dτ) are found to be about 5 nm at 650 °C for 30 min annealing. The diffusivity of Cu into single-crystal TaN follows the relation D=(160±9.5)exp[−(3.27±0.1)eV/kB T] cm2 s−1 in the temperature range of 600–700 °C. We observe that Cu diffusion in polycrystalline TaN thin films is nonuniform with enhanced diffusivities along the grain boundary.}, number={8}, journal={APPLIED PHYSICS LETTERS}, author={Wang, H and Tiwari, A and Zhang, X and Kvit, A and Narayan, J}, year={2002}, month={Aug}, pages={1453–1455} }
 @article{wang_tiwari_kvit_zhang_narayan_2002, title={Epitaxial growth of TaN thin films on Si(100) and Si(111) using a TiN buffer layer}, volume={80}, ISSN={["1077-3118"]}, DOI={10.1063/1.1466522}, abstractNote={We have deposited high-quality epitaxial B1 NaCl-structured TaN films on Si(100) and Si(111) substrates with TiN as the buffer layer, using pulsed laser deposition. Our method exploits the concept of lattice-matching epitaxy between TiN and TaN and domain-matching epitaxy between TiN and silicon. X-ray diffraction, transmission electron microscopy, and scanning transmission electron microscopy (Z-contrast) experiments confirmed the single-crystalline nature of the films with cube-on-cube epitaxy. The stoichiometry of the TaN films was determined to be nitrogen deficient (TaN0.95±0.05) by Rutherford backscattering. Resistivity of the TaN films was found to be ∼220 μΩ cm at room temperature with a temperature coefficient of resistivity of −0.5 μΩ K−1.}, number={13}, journal={APPLIED PHYSICS LETTERS}, author={Wang, H and Tiwari, A and Kvit, A and Zhang, X and Narayan, J}, year={2002}, month={Apr}, pages={2323–2325} }
 @article{zhang_wang_scattergood_narayan_koch_2003, title={Evolution of microstructure and mechanical properties of in situ consolidated bulk ultra-fine-grained and nanocrystalline Zn prepared by ball milling}, volume={344}, ISSN={["0921-5093"]}, DOI={10.1016/s0921-5093(02)00422-7}, abstractNote={The evolution of the microstructure and mechanical properties of ultra-fine-grained and nanocrystalline Zn induced by ball milling at room temperature are studied systematically. The yield stresses measured from miniaturized disk bend tests and tensile tests are consistent with the microhardness results and generally increase with the decrease of average grain size. A dramatic decrease of hardness during milling from 1 to 3 h is a reflection of the increase of average grain size from 80 to 240 nm due to the initial unstable grain size and therefore, grain growth in this period. Young's modulus remains almost the same for samples milled for different times and is that for conventional grain size Zn. A transition from bending to membrane stretching is observed in the force–displacement curves for Zn ball milled for ≤18 h. The variation of transition strain with milling time could be related to the evolution of grain size distribution and therefore hardness during milling.}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Zhang, X and Wang, H and Scattergood, RO and Narayan, J and Koch, CC}, year={2003}, month={Mar}, pages={175–181} }
 @article{zhang_wang_scattergood_narayan_koch_2002, title={Mechanical properties of cyromilled nanocrystalline Zn studied by the miniaturized disk bend test}, volume={50}, ISSN={["1359-6454"]}, DOI={10.1016/S1359-6454(02)00176-3}, abstractNote={The miniaturized disk bend test (MDBT) is useful for the study of the mechanical properties of small specimens in tension. The yield stress of cryomilled nanocrystalline Zn measured by MDBT shows periodic hardening and softening with milling time, consistent with the variation of microhardness with milling time. The periodic softening is due to the reduction of dislocation density controlled by dynamic recrystallization. The ductility of these softened nanocrystalline Zn specimens is consistently higher than that of the hardened specimens. Young's modulus shows little variation with the average grain size.}, number={13}, journal={ACTA MATERIALIA}, author={Zhang, X and Wang, H and Scattergood, RO and Narayan, J and Koch, CC}, year={2002}, month={Aug}, pages={3527–3533} }
 @article{zhang_wang_scattergood_narayan_koch_2002, title={Modulated oscillatory hardening and dynamic recrystallization in cryomilled nanocrystalline Zn}, volume={50}, ISSN={["1359-6454"]}, DOI={10.1016/S1359-6454(02)00199-4}, abstractNote={Oscillatory variation of the hardness with milling time was observed in cryomilled nanocrystalline Zn. Transmission electron microscopy showed that large variations in the dislocation density and grain-size distribution occurred during cryomilling. The observations suggest that recrystallization takes place in larger grains when the dislocation density due to strain-hardening reaches a critical level. A reaction-rate model was developed which accounts for the dynamic recrystallization effect and the observed oscillations in hardness. Good agreement was obtained with the experimental data. The results provide unique insight into grain-size effects and the interplay of these with deformation mechanisms and recrystallization effects in nanocrystalline materials.}, number={16}, journal={ACTA MATERIALIA}, author={Zhang, X and Wang, H and Scattergood, RO and Narayan, J and Koch, CC}, year={2002}, month={Sep}, pages={3995–4004} }
 @article{zhang_wang_kassem_narayan_koch_2002, title={Preparation of bulk ultrafine-grained and nanostructured Zn, Al and their alloys by in situ consolidation of powders during mechanical attrition}, volume={46}, ISSN={["1359-6462"]}, DOI={10.1016/S1359-6462(02)00048-9}, abstractNote={Bulk ultrafine-grained (UFG) or nanostructured Zn, Al and their alloys were produced via in situ consolidation of powders by mechanical attrition (MA) at room temperature. In situ consolidation of metal powders during MA may be a promising method to produce bulk UFG or nanostructured materials with full density and less contamination.}, number={9}, journal={SCRIPTA MATERIALIA}, author={Zhang, X and Wang, H and Kassem, M and Narayan, J and Koch, CC}, year={2002}, month={May}, pages={661–665} }
 @article{zhang_wang_scattergood_narayan_koch_sergueeva_mukherjee_2002, title={Studies of deformation mechanisms in ultra-fine-grained and nanostructured Zn}, volume={50}, ISSN={["1359-6454"]}, DOI={10.1016/S1359-6454(02)00349-X}, abstractNote={The temperature, strain rate, grain size and grain size distribution effects on plastic deformation in ultra-fine-grained (UFG) and nanocrystalline Zn are systematically studied. The decrease of ductility with the decrease of average grain size could be an inherent effect in nanocrystalline materials, that is, not determined by processing artifacts. The superior ductility observed in UFG Zn may originate from both dislocation creep within large grains and grain boundary sliding of small nanograins. The stress exponent for dislocation creep is about 6.6. The activation energy for plastic deformation in UFG Zn is close to the activation energy for grain boundary self diffusion in pure Zn.}, number={19}, journal={ACTA MATERIALIA}, author={Zhang, X and Wang, H and Scattergood, RO and Narayan, J and Koch, CC and Sergueeva, AV and Mukherjee, AK}, year={2002}, month={Nov}, pages={4823–4830} }
 @article{zhang_wang_scattergood_narayan_koch_sergueeva_mukherjee_2002, title={Tensile elongation (110%) observed in ultrafine-grained Zn at room temperature}, volume={81}, ISSN={["0003-6951"]}, DOI={10.1063/1.1494866}, abstractNote={Tensile tests were performed for Zn at room temperature, which show elongations of 110%–20% for average grain sizes of 240–23 nm, respectively. The ductility of ultrafine-grained and nanocrystalline Zn was found to decrease with grain size refinement. The deformation mechanisms in ultrafine-grained Zn are believed to be a mixture of grain boundary sliding of small nanograins and intra-grain dislocation creep within the large grains.}, number={5}, journal={APPLIED PHYSICS LETTERS}, author={Zhang, X and Wang, H and Scattergood, RO and Narayan, J and Koch, CC and Sergueeva, AV and Mukherjee, AK}, year={2002}, month={Jul}, pages={823–825} }
 @article{zhang_wang_narayan_koch_2001, title={Evidence for the formation mechanism of nanoscale microstructures in cryomilled Zn powder}, volume={49}, ISSN={["1873-2453"]}, DOI={10.1016/S1359-6454(01)00051-9}, abstractNote={Nanocrystalline Zn powder has been synthesized by a cryomilling method. The average grain size decreased exponentially with the cryomilling time and reached a minimum average grain size of around 17 nm. Large numbers of small grains (2∼6 nm) have been found in the very early stages of cryomilling. Dynamic recrystallization was used to explain the observed phenomena. The exothermic peaks revealed in the differential scanning calorimetry (DSC) results were correlated with the release of microstrain as confirmed by the x-ray diffraction measurements.}, number={8}, journal={ACTA MATERIALIA}, author={Zhang, X and Wang, H and Narayan, J and Koch, CC}, year={2001}, month={May}, pages={1319–1326} }
 @article{wang_sharma_kvit_wei_zhang_koch_narayan_2001, title={Mechanical properties of nanocrystalline and epitaxial TiN films on (100) silicon}, volume={16}, ISSN={["2044-5326"]}, DOI={10.1557/JMR.2001.0373}, abstractNote={We investigated mechanical properties of TiN as a function of microstructure varying from nanocrystalline to single crystal TiN films deposited on (100) silicon substrates. By varying the substrate temperature from 25 to 700 °C during pulsed laser deposition, the microstructure of TiN films changed from nanocrystalline (having a uniform grain size of 8 nm) to a single crystal epitaxial film on the silicon (100) substrate. The microstructure and epitaxial nature of these films were investigated using x-ray diffraction and high-resolution transmission electron microscopy. Hardness measurements were made using nanoindentation techniques. The nanocrystalline TiN contained numerous triple junctions without any presence of amorphous regions. The width of the grain boundary remained constant at less than 1 nm as a function of boundary angle. Similarly the grain boundary structure did not change with grain size. The hardness of TiN films decreased with decreasing grain size. This behavior was modeled recently involving grain boundary sliding, which is particularly relevant in the case of hard materials such as TiN.}, number={9}, journal={JOURNAL OF MATERIALS RESEARCH}, author={Wang, H and Sharma, A and Kvit, A and Wei, Q and Zhang, X and Koch, CC and Narayan, J}, year={2001}, month={Sep}, pages={2733–2738} }
 @article{zhang_wang_kassem_narayan_koch_2001, title={Origins of stored enthalpy in cryomilled nanocrystalline Zn}, volume={16}, ISSN={["0884-2914"]}, DOI={10.1557/JMR.2001.0479}, abstractNote={Nanocrystalline Zn was prepared by cryomilling (mechanical attrition at liquid nitrogen temperature). Differential scanning calorimetry (DSC), x-ray diffraction, and transmission electron microscopy were used to study the structural changes and grain size distribution with milling time and subsequent annealing. Maxima in both stored enthalpy (for the low-temperature DSC peak) and lattice strain on the Zn basal planes were observed at the same milling time. Dislocation density on the basal planes is proposed as a major source for lattice strain and the measured stored enthalpy. The released enthalpy that might be due to grain growth is very small.}, number={12}, journal={JOURNAL OF MATERIALS RESEARCH}, author={Zhang, XH and Wang, HY and Kassem, M and Narayan, J and Koch, CC}, year={2001}, month={Dec}, pages={3485–3495} }
 @article{dong_yoder_zhang_zhou_bestor_cheng_2001, title={Structure of human DNMT2, an enigmatic DNA methyltransferase homolog that displays denaturant-resistant binding to DNA}, volume={29}, ISSN={1362-4962}, url={http://dx.doi.org/10.1093/nar/29.2.439}, DOI={10.1093/nar/29.2.439}, abstractNote={DNMT2 is a human protein that displays strong sequence similarities to DNA (cytosine-5)-methyltransferases (m(5)C MTases) of both prokaryotes and eukaryotes. DNMT2 contains all 10 sequence motifs that are conserved among m(5)C MTases, including the consensus S:-adenosyl-L-methionine-binding motifs and the active site ProCys dipeptide. DNMT2 has close homologs in plants, insects and Schizosaccharomyces pombe, but no related sequence can be found in the genomes of Saccharomyces cerevisiae or Caenorhabditis elegans. The crystal structure of a deletion mutant of DNMT2 complexed with S-adenosyl-L-homocysteine (AdoHcy) has been determined at 1.8 A resolution. The structure of the large domain that contains the sequence motifs involved in catalysis is remarkably similar to that of M.HHAI, a confirmed bacterial m(5)C MTase, and the smaller target recognition domains of DNMT2 and M.HHAI are also closely related in overall structure. The small domain of DNMT2 contains three short helices that are not present in M.HHAI. DNMT2 binds AdoHcy in the same conformation as confirmed m(5)C MTases and, while DNMT2 shares all sequence and structural features with m(5)C MTases, it has failed to demonstrate detectable transmethylase activity. We show here that homologs of DNMT2, which are present in some organisms that are not known to methylate their genomes, contain a specific target-recognizing sequence motif including an invariant CysPheThr tripeptide. DNMT2 binds DNA to form a denaturant-resistant complex in vitro. While the biological function of DNMT2 is not yet known, the strong binding to DNA suggests that DNMT2 may mark specific sequences in the genome by binding to DNA through the specific target-recognizing motif.}, number={2}, journal={Nucleic Acids Research}, publisher={Oxford University Press (OUP)}, author={Dong, A. and Yoder, J.A. and Zhang, X. and Zhou, L. and Bestor, T.H. and Cheng, X.}, year={2001}, month={Jan}, pages={439–448} }