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Stress-controlled cyclic tests were conducted on bulk sheet Ni-carbonyl Chemical Vapor Deposited material (CVD Ni) with bimodal grain structures: ultrafine (UF) grains and large grains with UF/nano twins. The tests were run with the cyclic stress ratio R = 0.05 and peak stress level of 0.9–1.5 times of the material's yield strength. Results show that within the applied peak stress ratio of 0.9–1.1, the material demonstrated cyclic hardening behavior first, followed by stress–strain saturation till fracture; upon increasing the ratio to 1.4–1.5, an additional softening stage was activated and continued till fracture. By transmission electron microscope (TEM) examination, it was found that such cyclic deformation responses were associated with the stability of the ultrafine- and nano-twin structures. Initial hardening was found mainly due to the increase in dislocation density and the activities of dislocations especially with their strong interactions with the dense twin boundaries (TBs). The saturation was contributed by the simultaneous operations of the softening effect due to massive detwinning and the hardening behavior due to dislocation interactions with existing TBs. Newly formed dislocation walls and cell structures were further found in samples with stress ratio of 1.4 at fracture, corresponding to the softening stage. Furthermore, such microstructural evolution, which were observed also through annealing and monotonic deformation of the same material, is identified as a consistent energy reduction path for the material. Thus, an energy criterion is further established to predict the massive detwinning events that cause the major softening phenomena under cyclic deformation.

Nickel carbonyl vapor deposition (CVD) is a high-efficiency process used to produce nickel shell molds with high yield strength, reasonable ductility, and strong corrosion resistance. Such advantageous properties arise from the nanocrystals and nanotwins inside CVD nickel. However, the nanotwins do not persist at high temperatures, transforming into dislocation cells after 40-min annealing at 800 °C . Using experimental examinations and computational simulations, we investigated the kinetics of the annealing-induced detwinning in CVD nickel. TEM examinations showed that detwinning is realized by incoherent twin boundary (ITB) migration; meanwhile, plentiful dislocations are generated from coherent twin boundaries (CTBs). Our theoretical analysis revealed that these dislocations are necessary for the formation of the ITBs. Next, using molecular dynamics simulations, we found that the dislocations nucleated from CTBs during annealing are intrinsic grain boundary dislocations (IGBDs). Driven by the internal stress intensified by grain growth in the nanocrystalline regime, the IGBDs can separate from CTBs due to creep at 800 °C , resulting in a higher dislocation density inside the twin lamella than that of the outside. These dislocations can trigger the formation of ITBs. Overall, unlike grain growth, stress is necessary for detwinning, so a monolithic nanotwin structure should be more stable than the nanotwins inside a nanocrystalline matrix.

The adhesion strength between coating and substrate is the critical factor to attain high wear resistance and other properties of the coating. In this study, a novel method for evaluating the adhesion strength is employed to measure the shear strength of the interface between High Velocity Oxygen Fuel (HVOF) spraying WC-Co coating and Q345C steel substrate. The results showed that the crack initiated at the coating surface, then propagated towards the substrate, and finally stopped at the interface. Cracks perpendicular to strain direction was formed in prior. Cross-linked cracks parallel to the axis direction were found to form after the saturation of the crack formation in the coating perpendicular to strain direction. The average shear strength varied from 132.6 to 200.3 MPa. The maximum shear strength obtained could be as high as 354.6 MPa and the minimum shear strength was 74.9 MPa.

Temperate mixed forests, along with other high latitudinal ecosystems, are more vulnerable to global warming in comparison with warm sites, because of the slower carbon (C) turnover and higher soil organic carbon (SOC) accumulation. Lignin and cellulose are two major components of plant litter, and usually make contributions to the recalcitrant and labile SOC pool, respectively. Because the chemical composition of SOC plays key role in regulating the bioavailability of soil C pool, understanding the relationship between soil lignin or cellulose content and temperature are of great significance in evaluating the feedbacks between SOC pool and the future scenarios of global warming. The biological degradation of soil lignin or cellulose is mainly dependent on soil enzymatic activities, and thus, the response of ligninolytic and cellulolytic enzymes to increased temperature would determine C release under future warming scenarios. However, the responses of the soil lignin/cellulose content and the activity of cellulolytic and ligninolytic enzymes to increased mean annual temperature (MAT) have rarely been studied, and the factors driving these changes are not fully understood. Latitudinal gradients are often used for monitoring global-warming-related problems, because of its natural gradients of temperature. In this study, we demonstrate the latitudinal pattern of lignin/cellulose content and the activities of cellulose- and lignin- degrading enzymes in a temperate Broad-leaved Korean pine mixed forests distributed along a latitudinal gradient (with MAT ranging from −1.9 to 5.1 °C) in northeastern China. The linear mixed model revealed that soil lignin content was negatively correlated with MAT (Slope = −7.604, t = −2.608, P = 0.011), whereas soil cellulose content showed no response to increased MAT. The activity of soil polyphenol oxidase (PPO), one of the enzymes catalyze lignin decomposition, was higher in high-latitude sites, in contrast, the activity of the cellulase (CEL) complex was higher in low-latitude plots. Structural equation model (SEM) analysis indicates that MAT can directly influence soil lignin or cellulose content, and indirectly through changing NRCB, plant litter C/N, microbial biomass, and degrading enzymatic activities. The value of soil lignin/(lignin + cellulose) ratio and soil lignocellulose index (LCI, lignin/(lignin + holocellulose) ratio), varied between 0.8–0.9, and 0.6–0.8, respectively, indicating that the SOC pool in this temperate ecosystem is dominated by recalcitrant components. The negative correlations between MAT and LCI, soil lignin/(lignin + cellulose), and log (PPO + PER)/log(CEL) (Slope = −0.008, t = −2.363, P = 0.021; Slope = −0.004, t = −3.134, P = 0.003, and Slope = −0.057, t = −4.477, P

Through Ni-carbonyl CVD process, bulk Ni material (hereafter referred as CVD Ni) with bimodal grain structures, i.e. UF grains and large grains with UF/nano twins, can be produced. In tensile test, this material demonstrated a very good combination of strength and ductility as well as a special strain hardening behavior. Upon investigating the material's hardening behavior, a critical threshold strain, ec, of 0.02 was identified for the distinct change in the strain hardening behavior. Prior to this strain level, the strain hardening rate of the CVD Ni was found always higher than that of its counterpart coarse-grained (CG) Ni; but it dropped, after this strain, to the same level as the CG material. Furthermore, through the analysis of results from Tension Unloading Reloading-in-Tension (TURT) tests, this specific strain value was also found to be significant in the change of the hysteresis loop width as well as the back stress strain hardening responsible for the material's Bauschinger behavior. Microstructural evolution examination suggests that most of the twin boundaries (TBs) initially acted as obstacles to dislocation movement providing strong dislocation back stress and hence contributing to the strong hardening behavior. From the strain level of 0.02 and onwards, however, massive detwinning was detected which is responsible for the drop in the hardening rate. Finally, dislocation cell structures, that were typically evolved from entanglements of dislocation inside CG Ni, were also found inside the detwinned large grains of CVD Ni in the high strain regime, which yielded similar strain hardening behavior as in the CG Ni material.

Applications of mineral nitrogen (N) and phosphorus (P) fertilizer to grasslands become more frequently in recent decade, aiming to improve the grass production. Nonetheless, the ecological impacts of N and P fertilizer on ecosystem components, especially the belowground soil microbes, are not well acknowledged in grasslands ecosystem. We investigated the responses of plant traits, soil properties, bacterial community composition and potential functions to 5-year N and P fertilization in a mid-high latitude meadow grassland in Inner Mongolia, China. Bacterial species richness and diversity significantly (P

We demonstrate that modifying the cellular structures by well-controlled annealing can effectively improve the hydrogen embrittlement (HE) resistance of selective laser melting (SLM) processed alloys. Investigations on both as-SLM processed and annealed prototype CoCrFeMnNi high-entropy alloy samples suggest that annealing preserved the cellular structures while effectively reduced the dislocation densities. This slightly reduced the strength but significantly increased the ductility and HE resistance upon slow strain rate tensile tests (1 × 10−5 s-1) under in situ electrochemical hydrogen charging. The crack initiation and propagation were delayed by hydrogen-enhanced local plasticity with the formation of nano-twins and dislocation cells in the modified structures. © 2021 Elsevier Ltd

Stress-controlled cyclic tests were conducted on bulk sheet Ni-carbonyl Chemical Vapor Deposited material (CVD Ni) with bimodal grain structures: ultrafine (UF) grains and large grains with UF/nano twins. The tests were run with the cyclic stress ratio R=0.05 and peak stress level of 0.9 to 1.5 times of the material's yield strength. Results show that within the applied peak stress ratio of 0.9-1.1, the material demonstrated cyclic hardening behavior first, followed by stress-strain saturation till fracture; upon increasing the ratio to 1.4-1.5, an additional softening stage was activated and continued till fracture. By transmission electron microscope (TEM) examination, it was found that such cyclic deformation responses were associated with the stability of the ultrafine- and nano-twin structures. Initial hardening was found mainly due to the increase in dislocation density and the activities of dislocations especially with their strong interactions with the dense Twin Boundaries (TBs). The saturation was contributed by the simultaneous operations of the softening effect due to massive detwinning and the hardening behavior due to dislocation interactions with existing TBs. Newly formed dislocation walls and cell structures were further found in samples with stress ratio of 1.4 at fracture, corresponding to the softening stage. Furthermore, such microstructural evolution, which were observed also through annealing and monotonic deformation of the same material, is identified as a consistent energy reduction path for the material. Thus, an energy criterion is further established to predict the massive detwinning events that cause the major softening phenomena under cyclic deformation.

The purpose of this paper is to put forward a novel deformable tetrahedron rolling mechanism (DTRM). This new reconfigurable mobile mechanism with the external tetrahedral shape can be regarded as a parallel mechanism with a variable platform, that is constructed by four vertices and six edges corresponding to four platforms and six URU chains. Mechanical design is introduced, and the degree of freedom (DOF) is analyzed. Equivalent planar mechanism analysis method is proposed for the symmetrical mechanical structure to simplify the theoretical analysis process. Based on the symmetric-drive rolling locomotion, impact and non-impact rolling gait are planned, respectively corresponding to different joints workspace, to reduce the displacement error. Aiming at non-impact rolling gait, the motion strategy is established instead of moving with pre-set driving parameters, as the basis of the control system. Then a trajectory optimization of the center of mass (CM) based on actuator torque analysis is carried out to reduce the actuator torque. To verify the rolling locomotion, we present the results of a series of experiments, performed on a manufactured prototype.

Hydrogen induced stress corrosion cracking behavior of SUS301L-MT laser-arc hybrid welded (LAHW) joints has been investigated in our previous works. However, the hydrogen embrittlement (HE) behavior in each zone of this joint is still unclear. In this work, in combination with microstructures, cracks propagation paths and fracture surface morphologies analysis, in situ electrochemical hydrogen charging during slow strain rate tensile (SSRT) tests were performed on the specimens cut from base metal (BM), heat-affected zone (HAZ) and weld metal (WM) in SUS301L-MT stainless steel LAHW joints to investigate the HE behavior of each zone. The results indicated that deformation induced martensite transformation occurred in BM and HAZ specimens during SSRT tests, resulted in cleavage morphologies on the fracture center and dimples on other areas. The fracture surface of WM specimen was all covered with dimples. During in situ hydrogen charging, the cracks in BM and HAZ specimens initiated along αˊ/γ interface near the specimen edge. The cracks in WM specimen initiated along the δ-ferrites distributed at austenitic grain boundaries. After the cracks initiated, the hydrogen concentration distribution in combination with stress field at the front of cracks tips would induce the cracks propagation by “hydrogen enhanced local plastic deformation” and “hydrogen enhanced decohesion” mechanisms. As a result, mainly fracture characterizations of intergranular cracking, transgranular cleavage and secondary cracks formed on the fracture surface.

Increased nitrogen (N) input into the ecosystem, which is mainly caused by anthropogenic activities, is usually not paralleled by a similar increase in phosphorus (P) input, and thus, can shift the ecosystem from N limitation to P limitation. Although the effects of N enrichment on ecosystem components have been intensively evaluated, the impacts of altered P resource availability and the interactive effects of N and P on the biomass, composition, and function of soil microbial communities are not well understood. Here, based on a 9-year field experiment, we investigated the responses of soil biotic and abiotic properties to N and P addition in a semi-arid calcareous grassland in northern China. We documented a significant increase in the relative abundance of bacteria (copiotrophic group in a broad ecological meaning) and a decrease in the relative abundance of fungi (oligotrophic) and the fungi/bacteria (F/B) ratio under N addition. The proportion of arbuscular mycorrhizal fungi (AMF) decreased under both N addition and P addition. N addition and P addition inhibited N-acquisition enzymes (protease, PRO) and P-acquisition enzymes (alkaline phosphomonoesterases, Alka PME), respectively. N fertilization inhibited most of the soil enzymatic activities by reducing soil pH and microbial biomass. P addition alleviated the negative impacts of N addition on substrate induced respiration (SIR), peroxidase (PER), and Alka PME, likely by reducing the available N content in soils, but strengthened the effects of N on the soil total carbon (TC) content, which might contribute to increased plant productivity. We also found that the overall changes in soil microbial enzyme profiles in response to nutrient addition were mainly caused by eutrophication (changes in NO3−-N and Olsen-P), whereas variations in the broad community structure were driven by soil acidification. Overall, the application of N and P in this natural steppe will cause serious environmental issues and impact ecosystem service and function through changing the compositional and functional profiles of soil microbial communities.

A hypervirulent A. hydrophila (vAh) pathotype has been identified as the etiologic agent responsible for disease outbreaks in farmed carp species and channel catfish (Ictalurus punctatus) in China and the Southeastern United States, respectively. The possible route of infection has previously been unknown; however, virulence is believed to be multifactorial, involving the production/secretion of several virulence factors, including a high molecular weight group 4 capsular polysaccharide. Here we present chemical structural evidence of a novel capsule- and LPS-associated O-antigen found present in vAh isolated during these disease outbreaks. In this study, the chemical structure of the vAh O-antigen was determined by chemical analysis, Smith degradation, mass spectrometry, and 2D proton and carbon nuclear magnetic resonance (NMR) spectroscopy and found to be unique among described bacterial O-antigens. The O-antigen consists of hexasaccharide repeating units featuring a 4)-α-l-Fucp-(1-3)-β-d-GlcpNAc-(1-4)-α-l-Fucp-(1-4)-β-d-Glcp-(1- backbone, substituted with single residue side chains of α-d-Glcp and α-d-Quip3NAc linked to O-3 of the two fucose residues. The polysaccharide is partially O-acetylated on O-6 of the 4-substituted β-Glcp residue.

Objective This study tested the hypothesis that a ribose-based pre-treatment would protect the strength, ductility and toughness of γ-irradiation sterilized cortical bone. Methods Experiment 1: The effects of ribose pre-treatment (1.8 M in PBS at 60 °C for 24 h) prior to 33kGy of irradiation on strength, ductility and toughness (beams in three-point bending) and fracture toughness (J-integral at instability in single edge notched (bending)) were tested against matched non-irradiated and irradiated controls from bovine tibiae. Experiment 2: Three-point bending tests were conducted using beams from human femora (males, 59–67 years). Bone collagen thermal stability and network connectivity were examined using hydrothermal isometric tension testing. Results Ribose pre-treatment protected the strength, ductility and toughness of irradiation sterilized bovine and human specimens to differing degrees. Their ultimate strength was not detectably different from non-irradiated control levels; toughness in bovine and human specimens was protected by 57 and 76%, respectively. Untreated human bone was less affected by irradiation and ribose pre-treatment was more effective in human bone than bovine bone. Conclusions This paper presents the first proof-of-principle that irradiation-sterilized bone with improved mechanical properties can be produced through the application of a ribose pre-irradiation treatment, which provides a more stable and connected collagen network than found in conventionally irradiated controls.

The cyclic deformation response, CSSC behavior and microstructural evolution of oxygen free high conductivity polycrystalline copper samples were investigated under pure compression fatigue conditions. The results were compared with the observations made under symmetrical and pulsating tension fatigue. It was found that the cyclic deformation response, cyclic stress–strain curve and microstructural evolution of copper for pure compression fatigue condition are substantially different from those for push–pull fatigue. Unlike the symmetrical fatigue, rapid hardening and cyclic creep were observed in all tested compression fatigue conditions. To track surface micro-structural changes, optical and scanning electron microscopy (SEM), and atomic force measurement (AFM) were utilized. Dislocation structures were also examined using a transmission electron microscope (TEM) for different peak conditions after different numbers of cycles. The observations showed that cyclic plastic deformation accommodation by the material was not majorly contributed by the dislocation activities as evidenced by the very moderate slip activities on the surface as well as the lack of persistent slip band dislocation structures. Instead, cyclic creep was found to be the major form of plastic strain accommodation, which was found to be introduced though grain boundary activities, i.e. grain boundary extrusions.

Regulatory T cells (Tregs) have been widely recognized as crucial players in controlling immune responses. Because their major role is to ensure that the immune system is not over reactive, Tregs have been the focus of multiple research studies including those investigating transplantation tolerance, autoimmunity and cancer treatment. On their surface Tregs constitutively express CD25, a high affinity receptor for the cytokine interleukin-2 (IL-2). The reagents constructed in this study were generated by genetically linking porcine IL-2 to the truncated diphtheria toxin (DT390). This reagent functions by first binding to the cell surface via the porcine IL-2/porcine CD25 interaction then the DT390 domain facilitates internalization followed by inhibition of protein synthesis resulting in cell death. Four versions of the porcine IL-2 fusion toxin were designed in an interest to find the most effective isoform: 1) monovalent glycosylated porcine IL-2 fusion toxin (Gly); 2) monovalent non-N-glycosylated porcine IL-2 fusion toxin (NonGly); 3) bivalent glycosylated porcine IL-2 fusion toxin (Bi-Gly); 4) bivalent non-N-glycosylated porcine IL-2 fusion toxin (Bi-NonGly). Using a porcine CD25(+) B cell lymphoma cell line (LCL13271) in vitro analysis of the fusion toxins' ability to inhibit protein synthesis demonstrated that the Bi-NonGly fusion toxin is the most efficient reagent. These in vitro results are consistent with binding affinity as the Bi-NonGly fusion toxin binds strongest to CD25 on the same LCL13271 cells. The Bi-Gly fusion toxin significantly prolonged the survival (p=0.028) of tumor-bearing NOD/SCID IL-2 receptor γ(-/-) (NSG) mice injected with LCL13271 cells compared with untreated controls. This recombinant protein has great potential to function as a useful tool for in vivo depletion of porcine CD25(+) cells for studying immune regulation.

The binding motif of human CTLA-4 is well known to be MYPPPY and for porcine CTLA-4 the binding motif is LYPPPY. Is this single amino acid difference of methionine (M) versus leucine (L) critical for the CTLA-4 binding? Recently, we have reported that the recombinant soluble porcine CTLA-4 was incapable of binding to human CD80. In this study we mutated L to M in the binding motif of the soluble porcine CTLA-4 and mutated M to L in the binding motif of the soluble human CTLA-4. We then analyzed how these mutations affected the binding affinity of the mutants to both porcine and human CD80(+) cells. The soluble porcine CTLA-4-L97M mutant partially lost its binding affinity to porcine CD80 compared to the wild-type and conferred very weak binding ability to human CD80. These results indicate that the L in the binding motif of porcine CTLA-4 is important for determining its binding ability to porcine CD80. Wild-type soluble human CTLA-4 binds to both human and porcine CD80 with comparable affinity, however, the soluble human CTLA-4-M97L mutant almost lost its binding ability to human CD80 and increased its binding ability to porcine CD80. These results indicate that M in the human CTLA-4 binding motif is extremely critical for its binding to human CD80. Those data suggest that the human CTLA-4 based recombinant protein drugs such as human CTLA-4-Ig can be used and/or tested in a porcine model. Conversely, the use of porcine CTLA-4 based recombinant protein drugs such as porcine CTLA-4-Ig is restricted to swine models. The difference in binding specificity of CTLA-4 observed in this study may be useful for studies such as pig to nonhuman primate xeno-transplantation. Porcine CTLA-4- and human CTLA-4-M97L mutant-based recombinant protein drugs can be used to specifically block the direct presentation by donor antigen presenting cells in pig to nonhuman primate xeno-transplantation. Human CTLA-4-M97L mutant-based recombinant protein drugs will be more ideal as it is without immunogenicity to human being.

Galactofuranose (Galf) is the five-membered ring form of galactose. Although it is absent from mammalian glycans, it occurs as a structural and antigenic component of important cell surface molecules in a variety of microbes, ranging from bacteria to parasites and fungi. One such organism is Cryptococcus neoformans, a pathogenic yeast that causes lethal meningoencephalitis in immunocompromised individuals, particularly AIDS patients. C. neoformans is unique among fungal pathogens in bearing a complex polysaccharide capsule, a critical virulence factor reported to include Galf. Notably, how Galf modification contributes to the structure and function of the cryptococcal capsule is not known. We have determined that Galf is β1,2-linked to an unusual tetrasubstituted galactopyranose of the glucuronoxylomannogalactan (GXMGal) capsule polysaccharide. This discovery fills a longstanding gap in our understanding of a major polymer of the cryptococcal capsule. We also engineered a C. neoformans strain that lacks UDP-galactopyranose mutase; this enzyme forms UDP-Galf, the nucleotide sugar donor required for Galf addition. Mutase activity was required for the incorporation of Galf into glucuronoxylomannogalactan but was dispensable for vegetative growth, cell integrity, and virulence in a mouse model.

The evolution of microstructure upon different annealing conditions in the Ni-carbonyl chemical vapor deposited (CVD) Ni material was investigated systematically in the present study by differential scanning calorimetry (DSC), optical microscopy and transmission electron microscopy (TEM) with both ex situ and hot-stage in situ annealing approaches. TEM observations reveal that the as-deposited CVD nickel possesses a bi-modal grain structure, with large columnar grains embedded in a nano-grained matrix. The large columnar grains are found to be full of ultrafine- and nano-growth twins; there are also scattered fivefold symmetry grains as large as 3–5 μm. Microstructure observations upon annealing show that grain growth did not occur until annealing at 400 °C or higher, and the nano-grain matrix grew into large equaxial grains above 600 °C. A major microstructural evolution phenomenon, the detwinning process was observed at 400 °C or higher temperatures, and twin boundary receding in the detwinning process was found to have a number of mechanisms all involving dislocation activities. Upon annealing, the ultrafine- and nano-twins were found to transform into dislocation cell structures and this phenomenon is considered to be driven by the excess free energy associated with the high density of grown-in twin boundaries. The large sized, fivefold twinned grains found in the as-processed bulk deposited Ni are found to be thermally stable up to 600 °C. Surface dragging effect to twin and grain boundaries is detected during the hot-stage in situ TEM observation.

Co-stimulation blockade can be used to modulate the immune response for induction of organ transplantation tolerance, treatment of autoimmune disease as well as cancer treatment. Cytotoxic T-Lymphocyte Antigen-4 (CTLA-4), also known as CD152, is an important co-stimulatory molecule which serves as a negative regulator for T cell proliferation and differentiation. CTLA-4/CD28-CD80/CD86 pathway is a critical co-stimulatory pathway for adaptive immune response. T cell activation through the T cell receptor and CD28 leads to increased expression of CTLA-4, an inhibitory receptor for CD80 and CD86. MGH MHC-defined miniature swine provide a unique large animal model useful for preclinical studies of transplantation tolerance and immune regulation. In this study, we have expressed the codon-optimized soluble porcine CTLA-4 in the yeast Pichia pastoris system. The secreted porcine CTLA-4 was captured using Ni-Sepharose 6 fast flow resin and further purified using strong anion exchange resin Poros 50HQ. Glycosylation analysis using PNGase F demonstrated the N-linked glycosylation on Pichia pastoris expressed soluble porcine CTLA-4. To improve the expression level and facilitate the downstream purification we mutated the two potential N-linked glycosylation sites with non-polarized alanines by site-directed mutagenesis. Removal of the two N-glycosylation sites significantly improved the production level from ~2 mg/L to ~8 mg/L. Biotinylated glycosylated and non-N-glycosylated soluble porcine CTLA-4 both bind to a porcine CD80-expressing B-cell lymphoma cell line (KD = 13 nM) and competitively inhibit the binding of an anti-CD80 monoclonal antibody. The availability of soluble porcine CTLA-4, especially the non-N-glycosylated CTLA-4, will provide a very valuable tool for assessing co-stimulatory blockade treatment for translational studies in the clinically relevant porcine model.

Yeast Pichia pastoris has been widely utilized to express heterologous recombinant proteins. Pichia pastoris expressed recombinant porcine interleukin 3 (IL3) has been used for porcine stem cell mobilization in allo-hematopoietic cell transplantation models and pig-to-primate xeno-hematopoietic cell transplantation models in our lab for many years. Since the yeast glycosylation mechanism is not exactly the same as those of other mammalian cells, Pichia pastoris expressed high-mannose glycoprotein porcine IL3 has been shown to result in a decreased serum half-life. Previously this was avoided by separation of the non-glycosylated porcine IL-3 from the mixture of expressed glycosylated and non-glycosylated porcine IL-3. However, this process was very inefficient and lead to a poor yield following purification. To overcome this problem, we engineered a non-N-glycosylated version of porcine IL-3 by replacing the four potential N-glycosylation sites with four alanines. The codon-optimized non-N-glycosylated porcine IL3 gene was synthesized and expressed in Pichia pastoris. The expressed non-N-glycosylated porcine IL3 was captured using Ni-Sepharose 6 fast flow resin and further purified using strong anion exchange resin Poros 50 HQ. In vivo mobilization studies performed in our research facility demonstrated that the non-N-glycosylated porcine IL3 still keeps the original stem cell mobilization function.

Capsular polysaccharides (CPSs) were isolated from O-polysaccharide deficient strains of Burkholderia mallei and Burkholderia pseudomallei using a modified hot phenol/water extraction procedure. Glycosyl composition, methylation, MALDI-TOF MS analyses as well as (1)H NMR spectroscopy including COSY, TOCSY, NOESY, HMBC and HSQC experiments identified the presence of two distinct CPS antigens in the samples exhibiting the following structures: This study confirms the ability of B. mallei to express a 6-deoxy-heptan CPS and represents the first report of a mannan CPS being expressed by these bacterial pathogens.

Cyclic deformation response of Ti-5553 alloy with β–α bimodal structure is systematically studied through total strain controlled fatigue tests. Results on the relationship between mechanical response and microstructure evolution are presented in this report. It was found that cyclic hardening/softening behavior of the alloy depended strongly on the applied strain amplitude. At low strain levels, the material showed moderate hardening behavior at the early stage of cycling and then behaved elastically; whereas at high strain amplitudes, the alloy showed softening behavior from the beginning to the end of cycling. In the intermediate strain range, moderate hardening at the beginning followed by softening was detected. Transmission electron microscopy investigation revealed that such special macroscopic responses were due to the microstructure heterogeneity in the material. The activation and participation in the cyclic deformation of different constituents, namely the soft primary α p phase, the higher strength transformed β phase and the fine embedded α s precipitates in the β matrix played different roles at different strain levels and at different stages of cycling. Thus, the aforementioned specific cyclic hardening/softening behavior was introduced. Specifically, dislocation activities including activation of multiple slip systems and annihilation of pre-existing dislocations in the primary α p phase were found to play a very important role in the overall cyclic deformation behavior.

In some optimization problems, min(f"1,...,f"n) usually appears as the objective or in the constraint. These optimization problems are typically non-smooth, and so are beyond the domain of smooth optimization algorithms. In this paper, we construct smooth splines to approximate min(f"1,...,f"n) uniformly so that such optimization problems can be dealt with as smooth ones.

The anti-murine CD40L monoclonal antibody MR1 has been widely used in immunology research to block the CD40-CD40L interaction for induction of transplantation tolerance and to abrogate autoimmune diseases. The availability of recombinant CD40L with high binding capacity for MR1 would provide a valuable immunological research tool. In this study, we constructed the single chain murine soluble CD40L monomer, dimer, trimer and successfully expressed them in yeast Pichia pastoris under the control of the alcohol oxidase promoter. The secreted single chain murine soluble CD40L monomers, dimers, and trimers were initially enriched through histidine tag capture by Ni-Sepharose 6 fast flow resin and further purified on a cation exchange resin. Purity reached more than 95% for the monomer and dimer forms and more than 90% for the trimer. Protein yield following purification was 16 mg/L for the monomer and dimer, and 8 mg/L for the trimer. ELISA analysis demonstrated that the CD40L dimers and trimers correctly folded in conformations exposing the MR1 antigenic determinant.

A systematic investigation of the cyclic deformation behavior of OFHC copper processed by 7 cycles of accumulative roll bonding has been carried out. The ARB copper shows a unique composite natured microstructure with components of various grain sizes. Upon cyclic deformation, a general cyclic softening trend was observed. Due to the composite natured of the ARB copper microstructure, several micro-mechanisms have been observed to have activated for cyclic strain accommodation. These mechanisms were found to be activated in sequence rather than concurrently. The first of the mechanisms to activate is believed to be slip found in the pre-existing large equiaxed grains. Following the exhaustion of the above, the pre-existing shear bands were re-activated and further developed. It is believed that the strain incompatibility between the grains within the shear band and those outside was partially responsible for the coarsening of grains along the shear bands. The cyclic softening observed is believed to be related to the grain coarsening along the path of strain localization. However, due to the limited ductility and the abundance of crack nucleation sites, the cyclic lifespan of this ARB material was found not long enough for the extensive grain coarsening necessary in the development of a macro shear band. In an attempt to understand the behavior observed, the consideration of using a composite model is also discussed.

The cyclic deformation behavior of ultra fine grained copper after 7 cycles of accumulative roll bonding (ARB) have been systematically investigated under both load controlled and total strain controlled tests. The composite microstructure found in the as-ARBed samples has lead to unique behavior of this material. Cyclic softening as well as cyclic creep has been observed in asymmetrical cyclic tests. Grain coarsening was observed under both load controlled and total strain controlled tests. Cyclic softening behavior has been attributed to the grain coarsening phenomenon in the material. Surface damage due to shear banding was found to be the major failure mechanism. In addition, the coarsened grains have been detected to locate near and along the pre existent shear bands. The coarse grains already formed during the ARB-processing were shown to accommodate cyclic plastic strain by the formation of slip bands in their interior.

A simple, rapid and accurate liquid chromatography–tandem mass spectrometry (LC–MS/MS) method has been developed and validated for the determination of mildronate in human plasma. Following a simple protein precipitation with methanol, the analyte was separated on a C 18 column by isocratic elution with methanol and 10 mM ammonium acetate (55:45; v/v), and then analyzed by mass spectrometry in the positive ion MRM mode. Good linearity was achieved over a wide range of 0.01–20 μg/mL. The intra- and inter-batch precisions (as RSD, %) were less than 7.1%. The average extraction recovery was 87.5%. The method described above has been used, for the first time, to reveal the pharmacokinetics of mildronate injection in healthy subjects. After single intravenously administration of 250, 500 and 1000 mg mildronate, the elimination half-life ( t 1/2 ) were (5.56 ± 1.55), (6.46 ± 1.07) and (6.55 ± 1.17) h, respectively. The Student–Newman–Keuls test results showed that peak plasma concentration ( C max ) and the area under the plasma concentration versus time curve from time 0 to 24 h (AUC 0–24 ) were both linearly related to dose. The pharmacokinetics of mildronate fitted the linear dynamic feature over the dose range studied. The essential pharmacokinetic parameters of multidoses administration intravenously (500 mg, b.i.d) were as follows: t 1/2 was (15.34 ± 3.14) h; C max was (25.50 ± 3.63) μg/mL; AUC 0–24 was (58.56 ± 5.57) mg h/L. The t 1/2 and AUC of multidoses administration intravenously were different from those of single-dose administration significantly. These findings suggested that accumulation of mildronate in plasma occurred.

The assessment of ecological risk in genetically modified (GM) biological systems is critically important for decision-making and public acceptance. Cellular automata (CA) provide a potential modeling and simulation framework for representing relationships and interspecies interactions both temporally and spatially. In this paper, a simple subsystem contains only four species: crop, target pest, non-target pest and enemy insect, and a three layer arrangement of L × L stochastic cellular automata with a periodic boundary were established. The simulation of this simplified system showed abundant and sufficient complexity in population assembly and densities, suggesting a prospective application in ecological risk assessment of GM crops.

The structure of galactoxylomannan, a capsular polysaccharide from the opportunistic yeast Cryptococcus neoformans, was re-examined by NMR spectroscopy and GC-MS. The residue that is 3-linked to the side chain galactose and was previously assigned as beta-D-xylose [Vaishnav, V. V.; Bacon, B. E.; O'Neill, M.; Cherniak, R. Carbohydr. Res.1998, 306, 315-330] was determined to be beta-D-glucuronic acid. A revised structure for this polymer is presented, along with a proposal that this compound be termed glucuronoxylomannogalactan (GXMGal).

The results of mechanical testing on ultra-fine grained aluminum processed by accumulative roll-bonding (ARB) were analyzed with TEM observation and in accordance of the microstructural evolution upon annealing. It was found that rapid grain growth, with the corresponding decrease in strength, did not occur until the annealing temperature of 200 °C or higher. The oxide rolled into the material near the bonding interfaces was seen to act as an obstruction for grain boundary migration across said interfaces. More interestingly, the strain near the interface due to the surface preparation technique used during ARB was found to form discontinuous segregates consisting of smaller grains formed during annealing or even ARB processing of higher number of cycles. Such phenomenon is attributed to recovery or polygonization due to the strain incurred. This study has also demonstrated that yield point phenomenon may be observed in a commercially pure fcc metal when the grain size is within a certain range.

In this paper, we present a method of simultaneous blending of implicitly defined convex polyhedral angles and solid models. This algorithm starts with a new suitable partition of the n-simplex over which the algebraic splines are defined. Then a cubic algebraic spline is constructed which meets the initial surfaces with G^2 continuity. Examples are provided to demonstrate the blending process. The results show some advantages of the new blending method.

To better understand the effect of asperity on the crack closure and fatigue crack growth behavior, the load–CMOD relations and crack propagation rate were examined through the addition of artificial wedges into pre-cracks. Experimental results revealed that the unloading phase of the load vs. CMOD curve exhibited always a concave shape, signifying the acceleration in the CMOD decrease. This was related to the plastic deformation in the wedge as well as in the specimen material surrounding the wedge. With the addition of an artificial wedge, reduced fatigue crack growth rate was found. The crack growth rate was then correlated with the effective load intensity factor range, ΔPeff = Pmax − Pmin,real, which itself was correlated also to the deformation severity in the asperity as well as in the specimen material. Furthermore, the ΔPeff value was found to change with increasing the crack length. In a short crack range, approximately 0.1 mm crack length, the value of ΔPeff decreased due to the asperity- and plasticity-induced crack closing behavior. As the crack length increased, the ΔPeff value increased as well due to the reduction in the closing behavior until just prior to the final fracture. Based upon the ΔPeff variation as a function of crack length, details of the crack closing behavior were further discussed.

A prey–predator model of learning based on bit string with intelligence is developed in this paper. Three bit strings are taken into account which describe the health, the intelligence and the knowledge, respectively. A prey–predator ecosystem is simulated on lattices based on Monte-Carlo method. Then, we present the results of our simulations and discuss the evolution of population, intelligence and knowledge, respectively. From the results we find that for coexistence of predator and prey, higher average knowledge of the predator automatically leads to higher average intelligence of the prey. It can be concluded that each species has some advantage, thus they can coexist in an ecosystem for ever.

To better understand the crack closure effect in the fatigue process, influence of fatigue stress amplitude and R ratio on the contact features of fracture surfaces in an annealed carbon steel was studied via two special experimental approaches: (i) the collection of the fracture debris fallen from the crack surfaces, and (ii) the direct observation of the contact zones on the fracture surface through an ink dyeing method. The results of this study show that the change of fatigue CMOD value as a function of a/W ratio depends strongly on the loading condition; the fatigue stress amplitude and R ratio are the major factors that determine the contacting status between the mating fracture surfaces; the severity of the fracture surface contact can also be characterized by the dropping rate of the fracture debris particles collected during the fatigue test.

The load–crack opening displacement (COD) curves and deformation characteristics in the vicinity of a hard artificial asperity in an annealed SAE 1015 steel were studied. The artificial asperity was found to have a significant effect on the trend of the load–COD curves. The lower portion of the load–COD curves in the unloading phase exhibited a convex shape without the asperity, but a concave shape with the asperity. The concave shape, signifying the acceleration in the COD decrease, was further verified by varying the size of the asperity, conducting special compression tests and elastic–plastic load–COD tests. The plastic deformation in the vicinity of both asperity and crack tip was studied via microhardness tests, etching techniques, and finite element analysis. Based on the experimental observations, a modified crack closure process model was proposed, where three stages of the unloading curve was defined: (i) the asperity does not contact the upper crack face, (ii) a process where both the asperity and the specimen material deform elastically, and the elastic-wedge model is applicable, and (iii) the plastic deformation of the specimen material adjacent to the asperity occurs, thus resulting in the concavely shaped load–COD curves. An equation was proposed to estimate the COD values, in which the plastic deformation both at the crack tip and at the asperity was considered. The residual COD calculated from the proposed equation was found to be consistent with the experimental results.

The monoclonal antibody FN18 has been used as a marker for monkey T cells and as a T cell depleting reagent when conjugated to binding site mutants of diphtheria toxin. This anti-CD3 antibody shares certain properties with its anti-human counterparts UCHT1, OKT3 and Leu-4 in that it precipitates two different CD3 chains from membrane detergent extracts. However, in contrast to human CD3, rhesus and cynomolgus monkeys display CD3 polymorphisms producing FN18 negative phenotypes. Using recently published sequence data, we have expressed the ectodomains of cynomolgus CD3-epsilon CD3-gamma and CD-delta chains in E. coli, and have refolded these chains separately and in pairs to produce CD3 homo- and heterodimeric proteins. These proteins were fractionated by anion exchange according to their differing isoelectric points and further identified by size differences on SDS gels. On the basis of ELISA, the FN18 epitope is restricted to the CD3-epsilongamma ectodomain heterodimer, CD-epsilondelta and CD-epsilonepsilon being non-reactive. Either of the two amino acid polymorphisms reported in the CD3-epsilon chain were sufficient to degrade the bioactivity of the CD3-epsilongamma towards FN18.

The Ohno continuous casting (OCC) process has been used to generate 62% Bi–Sn alloy wires approximately 2 mm in diameter with eutectic morphology at speeds between 30 and 387 mm/min. The microstructure was examined and tensile tests performed for wires cast at various speeds. The deformation behavior was investigated by observing the surface structure of wires at various tensile deformation stages. It was found that the eutectic morphology was of a quasi complex-regular structure for wires cast at higher speeds, whereas at lower speeds it contained a remnant of Chinese script type structure. It was found that bismuth fracture begins before inter-phase cracking in the initial stages and proceeds concurrently with inter-phase cracks in the latter part of the deformation process, allowing the accommodation of large strain. For wires cast at higher speeds, the inter-phase cracks play a leading role in wire fracture, whereas for wires cast at lower speeds, the bismuth fracture exerts a leading role in crack propagation and fracture. This difference was manifested in the fracture surface and elongation value.

Transmission electron microscopy observations of the recovered slugs of electroformed copper liner materials that had undergone high-strain-rate deformation show the existence of a wide range of crystal defects, including vacancy clusters and porosity. Cellular structures formed by tangled dislocations and subgrain boundaries consisting of dislocation arrays were also detected. Electron backscattering Kikuchi pattern technique analysis reveals that the fibrous texture observed in the as-formed copper liners of shaped charges disappeared after explosive detonation deformation. In a specimen that had been plastically deformed at a normal strain rate (4×10 −4 s −1 ), a high density of dislocations was observed within grains. These experimental results indicate that dynamic recovery and recrystallization play an important role during high-strain-rate deformation by virtue of a temperature increase in the deformation process, whereas the conventional slip mechanism operates during deformation at the normal strain rates.

ErbB2 receptor (HER2) tyrosine kinase was overexpressed in about 25% breast cancers, and was correlated with extremely aggressive phenotype and poor prognosis. Lapatinib, an oral, reversible inhibitor of both ErbB2 and EGFR tyrosine kinases, was approved in combination with capecitabine for treating advanced stage ErbB2 positive breast cancers. However, the clinical response of Lapatinib was seriously limited by the drug resistance. We established the Lapatinib resistant breast cancer cell lines and the preliminary data demonstrated the increased autophagosome formation in the stable resistant cells. The resistant cells were re-sensitized to Lapatinib after treated with autophagy inhibitor. According to our preliminary data and related reference, we hypothesized that autophagy could facilitate the ErbB2 positive breast cancer cells to be Lapatinib resistant and promoted the survival of the resistant cells. The abrogation of autophagy might restore the drug sensitivity. Autophagy might be one of the targets to overcome the Lapatinib resistance.

In order to understand the mechanism of sag behavior of engineering materials, systematic symmetrical and asymmetrical cyclic loading tests, rather than stress relaxation and the Bauschinger effect test, were carried out with two model materials, namely industrial pure iron and spheroidized mid-carbon steel, under different pre-strain conditions. It was found that the applied mean stress had a significant effect on the amount of cumulative cyclic creep strain and it could also strongly extend the secondary creep stage. It was also found that the Bauschinger effect caused by pre-strain would become negligible in cyclic deformation after a certain, but small number of cycles. This indicates that Bauschinger effect test cannot thoroughly reflect the nature of sagging behavior. Finally, both increase in the pre-strain level, and decrease in the cyclic peak stress level resulted in reduced amount of energy that could be recovered by cyclic deformation from the total energy accommodated during pre-plastic straining. On the other hand, it is such unrecovered energy that would make the material enter a stable stage of dislocation substructure earlier during cycling.

The dislocation structures of Cu-30% Zn single crystals cyclically deformed at gamma(pl) = 3.8 x 10(-5)-6.4 x 10(-3) were studied through transmission electron microscopy in order to understand the cyclic deformation mechanisms of the material. It has been shown that the fatigue dislocation structures have two basic configurations depending on the strain amplitude applied. At low strain amplitudes (gamma(pl) 3.0 x 10(-4)), however, the dislocation structure is dominated by planar dislocation loops and tangles; in this case a small amount of dislocation multipoles and a special zigzagged structure are also detected. Secondary slips were found to be activated from a very low strain amplitude (gamma(pl) = 3.8 x 10(-5)). This behavior is attributed to (i) the lower stress for dislocation generation compared with cyclic dow stresses and (ii) heterogeneous deformation at low strain amplitudes that results in a weak effect of local latent hardening. Cyclic deformation mechanisms at low and high strain amplitudes have been discussed in terms of the motion of dislocation multipoles and the dislocation reactions between the primary and secondary slip systems. The critical strain amplitude for the transition of the deformation mechanisms has been also theoretically determined to be 3 x 10(-4), in good agreement with results on the cyclic deformation response and the features of dislocation structures. The formation of specific dislocation structures such as the zigzagged structure has been discussed with detailed dislocation mechanisms. (C) 1998 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.

Cyclic deformation behavior of Cu-30% Zn single crystals oriented for single slip was studied at constant plastic shear strain amplitudes (gamma(pl)) in the range of 3.8 x 10(-5)-6.4 x 10(-3) in order to understand systematically the fundamental fatigue behavior of low stacking fault energy materials. Results indicate that the cyclic hardening behavior strongly depends on the strain amplitude applied. For low strain amplitudes (gamma(pl)

Energy associated with specific dislocation configurations such as loops and dipoles has long been a topic in the field of dislocation theory. Specifically, in the past thirty years or so, discussion on the energy associated with characteristic dislocation structures such as Persistent Slip Bands (PSBs) and cell structures induced by cyclic deformation process, has attracted much more attention because the formation of such structures as PSBs is probably the most important feature of the cyclic deformation and fatigue response of high stacking fault energy materials, say Cu. The importance of such a feature, PSB formation, is reflected by the very fact that it directly indicates the most important mechanical phenomena of these materials in cyclic deformation including strain localization, formation of extrusion/intrusion pairs and, finally, fatigue crack initiation. The present study is designed and carried out in order to experimentally observe the thermal stability of dislocation structures. Specifically, as the thermal evolution of dislocation structures produced in static deformation has been discussed thoroughly by Martin et al., the author will concentrate on the evaluation of cyclic deformation-induced structures upon thermal activation. The project has been carried out in a form of comparison between cyclically deformed samples and statically deformed samplesmore » of an identical material.« less

Friction stress and back stress of [001] Cu single crystals during cyclic deformation were derived from cyclic stress-strain hysteresis loops by using the Cottrell method and the results are compared with those for single slip crystals. The cyclic hardening features of the [001] crystals are described in terms of the friction stress and back stress. Specific, detailed study was carried out on the sample cycled with a plastic strain amplitude of 1.8 x 10(-3). It has been shown that both the 'true' friction stress, i.e. the cyclic yield stress, and the back stress in the [001] crystals increase much more rapidly than those in single slip crystals in the hardening stage. In the saturation stage, however, only the friction stress in the [001] crystal is higher than its correspondent in the single slip crystals, while the back stresses in these two types of crystals are close to each other. The higher friction stress in the [001] crystal is related to the higher density of jogs produced by the dislocation reactions between the primary and critical slip systems, and the existence of secondary dislocations in channels. The higher back stress in the hardening stage is attributed to the higher dislocation density in loop patches introduced by dislocation reactions in the first dozen of cycles. By modifying the Kulhlmann-Wilsdorf and Laird model, it is possible now to express quantitatively both the back stress and the shear stress in a cyclically deformed crystal with a particular orientation as functions of the applied strain amplitude as well as an orientation-dependent factor: the hardening coefficient for the first stage of unidirectional deformation. The predictions from these expressions for multiple slip crystals are in very good agreement with experimental data. (C) 1998 Elsevier Science S.A. All rights reserved.

In recent years, electron channeling contrast (ECC) technique accomplished in conventional scanning electron microscopes (SEM) has received much interest in studying dislocation configuration in deformed materials, especially in cyclically deformed materials. This technique can not only provide a real and wide view of dislocation substructures conveniently, but also make it possible to establish relationship between the surface structures, such as slip bands, and the bulk dislocation structures due to the unique feature of this technique. The present study is to use ECC technique to reveal the dislocation substructures of macro deformation bands formed in fatigued [001] Cu single crystals. The ECC results will also be correlated with those of light microscopy and transmission electron microscopy (TEM) studies.

Deformation processes of nanocrystalline (6–40 nm) nickel produced by an electrodeposition technique were studied. First, the results of unidirectional tensile tests were discussed with respect to the deviation from the Hall-Petch relationship. It was suggested that such a mechanical behavior exhibited by nanocrystalline materials could be described by a composite model proposed previously. Further experimental work on static and dynamic creep tests under the load control condition showed that nanocrystalline nickel electrodeposits exhibited a significant room temperature creep behavior. It appeared that grain boundary sliding and diffusive matter transport within the intercrystalline region played an important role in terms of deformation mechanisms of nanocrystalline materials. The contributions of dynamic creep to stress-strain behavior and, in turn, to the assessment of the Hall-Petch relationship for nanocrystalline materials are discussed.

Cyclic deformation behavior of [001] copper single crystals was investigated in symmetrical pull-push fatigue tests at the ambient temperature and with constant plastic shear strain amplitudes ( γ pl ) in the range of 1.0 × 10 −4 to 3.0 × 10 −3 . The formation and development of surface slip bands (SBs) were examined in situ by a light microscope. A rapid initial hardening stage followed by a pronounced overshooting or significant softening was found with the crystals tested at γ pl ≥ 4.8 × 10 −4 . The cyclic stress-strain curve of [001] crystals does not show any plateau behavior, instead it follows, if corrected with the Taylor factor, the power law function for copper polycrystals. The fatigue limit, defined as the critical strain amplitude below which SBs do not form, was found to be approximately 1.7 × 10 −4 , a value much higher than that for single slip oriented crystals, but very close to that for polycrystals modified by the Taylor factor. In situ observation revealed that the primary SBs appeared at the very beginning of cyclic deformation and frequently they were not persistent. The secondary (critical) SBs usually formed at the overshooting stage after rapid hardening. Deformation bands with the characteristics of kink bands were detected in the final stage of the cyclic deformation. Analysis indicated that the rapid initial cyclic hardening is caused by the formation of Lomer-Cottrell locks, while the overshooting/softening behavior is related to the operation of secondary slip or the formation of dislocation labyrinth structure. The preferred combination of primary and critical slip during cyclic deformation is also discussed in terms of dislocation reactions.

The grain growth kinetics of nanocrystalline nickel electrodeposits was studied by transmission electron microscopy and differential scanning calorimetry at different heating rates. It was found that, upon annealing, the nanocrystals in the nickel electrodeposits appeared to grow abnormally and released about 415.7 ± 3.5 J/mol of heat. The mechanism of the abnormal grain growth was attributed to the subgrain coalescence. The method for determination of the grain growth activation energy as well as all the other kinetic parameters in the Johnson-Mehl-Avrami equation was proposed based on an isokinetic analysis. This method is applicable to general types of transformation process governed by a single activation energy under the isokinetic condition. The activation energy for the grain growth of nanocrystalline nickel electrodeposits was found to be about 131.5 kJ/mol using this method. The difference between the present method and the Kissinger and Ozawa method was addressed in terms of their physical backgrounds.

The dislocation structure of [001] Cu single crystals developed in cyclic deformation has been systematically studied with transmission electron microscopy and related to the mechanical behavior presented previously. The dislocation configuration for this orientation is characterized by labyrinth structures over all the strain amplitudes investigated. At high strain amplitudes ( γ pl = 1.8 × 10 −3 −3.0 × 10 −3 ), additional structures such as exclusive walls and strips were observed. The strips are parallel to {111} slip planes and are associated with macro-deformation bands reported previously. At low strain amplitudes ( γ pl ≤ 2.4 × 10 −4 ), however, labyrinth becomes irregular in geometrical shape. Labyrinth structures consist of two types of perpendicular walls: one is always parallel to (001) plane and the other may be (100), (210) or (120). The characteristic dimension of labyrinths, such as channel width, increases with decreasing applied strain amplitude. The nature of dislocations in labyrinth structures was identified to be mainly primary and critical dislocations. The role of labyrinth structures in cyclic deformation was discussed in terms of geometrical considerations. It has been shown that labyrinth structures are more favorable to cyclic deformation by promoting multiple slip and cross slip. Finally, the cyclic saturation stress was quantitatively correlated with the microparameter of labyrinth structures.