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ABSTRACTThanks to rapid cooling rates and small melt pool sizes, selective laser melting (SLM) can be used to create novel microstructures difficult or impossible to achieve otherwise. This article overviews two types of SLM-fabricated Ti alloys exhibiting excellent strength and ductility. First, fully martensitic Ti-6Al-4 V alloys are produced with high yield strengths of >1100 MPa and total elongations of ~12–14%, comparable to those in fine α/β lamellar Ti-6Al-4 V. Second, hybridisation of different microstructures from existing alloys to generate a ‘composite of microstructures’ is introduced as a new strategy for producing heterogenous alloys with significantly enhanced performances. In particular, Ti alloys hybridised from different classes of Ti (α, α-β and β) have exhibited an excellent combination of high strength, work hardening ability and ductility, superior to conventional pure Ti andTi alloys.

[Display omitted] • Non-shearing particles alter the grain refinement sequences found in particle free metal during severe plastic deformation. • Influence on grain refinement dependent on stacking fault energy, deformation temperature, particle size, and morphology. • At elevated temperatures, coarse particles facilitate dynamic recrystallization in surrounding deformation zones. • Fine particles delay grain refinement by hindering twin formation, which is a key mechanism for low stacking fault energy. • Broken lamellae accelerate grain refinement by creating numerous high angle grain boundaries to initiate recrystallization. The influence of particle size and morphology on grain refinement in low stacking fault energy (SFE) alloys was studied by comparing the grain structures in single- and multi-phase Al-bronze (AB) alloys following equal channel angular pressing (ECAP) between 350 and 500 °C. In particular, nickel aluminium bronze (NAB) was chosen as it contained both coarse and fine rounded particles, as well as a lamellar phase which evolved during ECAP. Grain refinement in the single-phase alloy was achieved through dynamic recrystallisation initiated at deformed twin boundaries. By contrast, different mechanisms were observed in the particle-containing NAB. Recrystallisation around the coarse κ II particles (∼5 μm) was promoted through particle stimulated nucleation (PSN), whereas recrystallisation in the region of the fine κ IV (∼0.4 μm) was delayed due to the activation of secondary slip. Grain refinement in areas of the lamellar κ III showed significant variation, depending on the lamellar orientation relative to the shear plane of ECAP. As the lamellae deformed, numerous high angle grain boundaries were generated between fragments and served as nucleation sites for recrystallisation, while PSN occurred around spheroidised lamellae. The spreading of the κ III particles by ECAP then enhanced the total area of recrystallised grains. [ABSTRACT FROM AUTHOR]

In a heavy-duty gas turbine, when hot rotor is left cooled in standstill condition, thermal bow occurs due to natural convection, which may result in high vibrations in a subsequent restart. Usually, a turning gear is immediately started after shutdown of gas turbine to slowly roll and uniformly cool the rotor in order to prevent thermal bow, which is called turning gear operation. The minimum turning time and the acceptable temperature of wheel space are two important indexes of turning gear operation, and their determination highly depends on accurate prediction of thermal bow. This paper proposes an analytical method to predict the thermal bow behavior of rotors with complex structures and investigates the effect of turning time on thermal bow. First, the general form of analytical solution of rotor thermal bow is derived and validated through both finite element analysis and experiments. Then the analytical solution is applied in a heavy-duty gas turbine to predict the most severe thermal bow behavior of the rotor with no turning gear in operation before standstill. Finally, the effect of turning time on thermal bow is investigated, and the indexes to achieve acceptable thermal bow are discussed. Results show that the shape of thermal bow of the gas turbine rotor is close to the first-order mode shape; the peak of the most severe thermal bow reaches 0.7 mm after 3.8 h of cooling and the decrease of thermal bow is much slower than the increase. Besides, the maximum thermal bow of the rotor due to insufficient turning gear operation presents an exponential decay with turning time and lies in linear relationship with the temperature of the same location. These two relationships help determine the minimum turning time and acceptable temperature of wheel space to attain an acceptable bow and thus have practical significance to develop and optimize turning gear operations.

Circumferential tie-rods fastened rotor is a common structure widely used in gas turbine. The preloads of rod groups are of great importance to ensure the strength, stiffness, and stability of the rotor in gas turbine. The tensile force of rods obtained through preload may change due to inconsistent axial thermal expansions between rods and discs during transient startup and shutdown processes, and the change should be within the safety margin. Based on the finite element method, thermal-structural analyses of a gas turbine are carried out to quantify the effect of temperature field on tensile force of rods under multiple operating conditions including steady state, shutdown process, turning gear operation, startup, and standstill. Results show that the maximum increase of the tensile force of rods reaches about 33% and 25% for the compressor and turbine shafts during startup. The tensile force of rod-groups presents nonuniform distribution with sine wave shapes during the standstill condition, and the unevenness is highly relative to the time on turning gear. The quantitative results provide a theoretical reference for the preload design of rods in gas turbine.

Chronic cough (CC) is a cough lasting ≥ 8 weeks for adults. Data on prevalence, comorbidities, healthcare resource utilization (HCRU) and health-related quality of life (HRQoL) of CC adults in China is lacking.

The search for genetic variants underlying major depressive disorder (MDD) has not yet provided firm leads to its underlying molecular biology. A complementary approach is to study gene expression in relation to MDD. We measured gene expression in peripheral blood from 1848 subjects from The Netherlands Study of Depression and Anxiety. Subjects were divided into current MDD (N=882), remitted MDD (N=635) and control (N=331) groups. MDD status and gene expression were measured again 2 years later in 414 subjects. The strongest gene expression differences were between the current MDD and control groups (129 genes at false-discovery rate, FDR<0.1). Gene expression differences across MDD status were largely unrelated to antidepressant use, inflammatory status and blood cell counts. Genes associated with MDD were enriched for interleukin-6 (IL-6)-signaling and natural killer (NK) cell pathways. We identified 13 gene expression clusters with specific clusters enriched for genes involved in NK cell activation (downregulated in current MDD, FDR=5.8 × 10-5) and IL-6 pathways (upregulated in current MDD, FDR=3.2 × 10-3). Longitudinal analyses largely confirmed results observed in the cross-sectional data. Comparisons of gene expression results to the Psychiatric Genomics Consortium (PGC) MDD genome-wide association study results revealed overlap with DVL3. In conclusion, multiple gene expression associations with MDD were identified and suggest a measurable impact of current MDD state on gene expression. Identified genes and gene clusters are enriched with immune pathways previously associated with the etiology of MDD, in line with the immune suppression and immune activation hypothesis of MDD.

Waste Electrical and Electronic Equipment (WEEE) are one of the most significant waste products in modern societies. Disassembly is a critical step to reduce Electrical and Electronic Equipment (EEE) waste. In the past two decades, despite disassembly has been applied to support recycling and remanufacturing of WEEE products worldwide, full disassembly of WEEE is rarely an ideal solution due to high disassembly cost. Disassembly planning and sequencing has therefore become an important but still a challenging research topic in recent years. In this paper, based on product model, space interference matrix can be generated to represent the space interference relationship between each component of product, and all feasible disassembly sequences can be obtained by analysing the space interference matrix in six directions in a 3D environment. The obtained feasible disassembly sequences can be used as solutions to support our developed Particle Swarm Optimisation (PSO)-based selective disassembly planning method to search optimised selective disassembly sequence for Liquid Crystal Display (LCD) televisions.

Ti-6Al-4V machining chips have been recycled into fully dense material by a solid-state process based on equal channel angular pressing (ECAP). The as-recycled material possessed a refined microstructure and contained a series of oxide layers associated with the boundary of each machining chip. The chip boundaries were observed to dissolve into interstitial solid solution following static annealing. A series of static heat treatments within the temperature range 700 to 1000°C, for durations of between 1 and 20 hours, were performed. The effect of thermomechanical processing on microstructure and mechanical properties is discussed and compared to the as-recycled and commercially available materials.

Mutations in the PLA2G6gene at the PARK14 locus have been reported in complicated parkinsonism. To assess the prevalence of and phenotypes associated with PLA2G6gene mutations, we screened PLA2G6mutations in a cohort of patients with autosomal recessive early-onset parkinsonism (AREP).

The collective dynamics of magnetic domain wall under electric current is studied in the form of spin transfer torque (STT). The out-of-plane STT induced effective force is obtained based on the Landau-Lifshitz-Gilbert (LLG) equation including microscopic STT terms. The relation between microscopic calculations and collective description of the domain wall motion is established. With our numerical calculations based on tight binding free electron model, we find that the non adiabatic out-of-plane torque components have considerable non-local properties. It turns out that the calculated effective forces decay significantly with increasing domain wall widths.

Laser powder bed fusion (LPBF) was employed to produce Fe and Fe-(10–50 vol%) Cu immiscible alloys using elemental powders. The addition of 10 vol% Cu to Fe resulted in ultrahigh compressive yield and ultimate strengths of >~ 1000 and ~ 1400 MPa (more than 2 times greater than those in LPBF Fe and 4–6 times than in conventionally processed Fe), respectively, with fracture strain of ~ 20%. However, a further increase in the amount of Cu gave rise to significantly more heterogeneous microstructures with non-uniform distribution of Cu, leading to considerable liquation cracking, large voids and reduced strength and plasticity. Strengthening was primarily attributable to the dispersion of nano-Cu particles of 2–5 nm with spacings of < 10 nm and ultrafine grains (<~ 50–300 nm). The substantial grain refinement in Fe-Cu alloys during LPBF was mainly a result of the confinement of Fe crystals by Cu films, hindering their growth. By analysing microstructures in single laser tracks, single layers, top and middle sections of the LPBF Fe, it was revealed that constitutional undercooling during solidification or the subsequent transformations of γ → α were responsible for the formation of equiaxed, rather than columnar, grains in pure Fe.

Background: In gene therapy, one of the most important issues is the choice of the vectors. pHrneo is a human‐derived vector previously constructed by our group, which can target a foreign gene into a human ribosomal DNA (hrDNA) locus. Methods and results: In this study, we inserted an expression cassette of reconstructive hFVIII (hFVIII‐BDDAK39) to pHrneo to construct a targeting vector: pHrneo‐BDDAK39. Through electroporation of pHrneo‐BDDAK39 into HL7702 cells (human hepatocyte), we identified the homologous recombinants using polymerase chain reaction, and tested the expression of hFVIII–BDDAK39 located at the hrDNA locus. The hFVIII‐BDDAK39 was successfully targeted into the hrDNA locus of HL7702 by pHrneo‐BDDAK39, and the efficiency of site‐specific integration was 1.1 × 10−5. The hFVIII‐BDDAK39 at the hrDNA locus of HL7702 was found to be able to express efficiently (4.3 ± 0.9 ng 10−6 cells 24 h−1). Conclusion: It has been indicated that the targeting vector pHrneo‐BDDAK39 can be used in gene therapy for hemophilia A.

The correlations between Caco-2 permeability (logPapp) and molecular properties have been investigated. A training set of 77 structurally diverse organic molecules was used to construct significant QSAR models for Caco-2 cell permeation. Cellular permeation was found to depend primarily upon experimental distribution coefficient (logD) at pH 7.4, high charged polar surface area (HCPSA), and radius of gyration (rgyr). Among these three descriptors, logDmay have the largest impact on diffusion through Caco-2 cell because logDshows obvious linear correlation with logPapp(r0.703) when logDis smaller than 2.0. High polar surface area will be unfavorable to achieve good Caco-2 permeability because higher polar surface area will introduce stronger H-bonding interactions between Caco-2 cells and drugs. The comparison among HCPSA, PSA (polar surface area), and TPSA (topological polar surface area) implies that high-charged atoms may be more important to the interactions between Caco-2 cell and drugs. Besides logDand HCPSA, rgyr is also closely connected with Caco-2 permeabilities. The molecules with larger rgyr are more difficult to cross Caco-2 monolayers than those with smaller rgyr. The descriptors included in the prediction models permit the interpretation in structural terms of the passive permeability process, evidencing the main role of lipholiphicity, H-bonding, and bulk properties. Besides these three molecular descriptors, the influence of other molecular descriptors was also investigated. From the calculated results, it can be found that introducing descriptors concerned with molecular flexibility can improve the linear correlation. The resulting model with four descriptors bears good statistical significance, n 77, r 0.82, q 0.79, s 0.45, F 35.7. The actual predictive abilities of the QSAR model were validated through an external validation test set of 23 diverse compounds. The predictions for the tested compounds are as the same accuracy as the compounds of the training set and significantly better than those predicted by using the model reported. The good predictive ability suggests that the proposed model may be a good tool for fast screening of logPappfor compound libraries or large sets of new chemical entities via combinatorial chemistry synthesis.

A novel method for the estimation of aqueous solubility was solely based on simple atom contribution. Each atom in a molecule has its own contribution to aqueous solubility and was developed. Altogether 76 atom types were used to classify atoms with different chemical environments. Moreover, two correction factors, including hydrophobic carbon and square of molecular weight, were used to account for the inter-/intramolecular hydrophobic interactions and bulkiness effect. The contribution coefficients of different atom types and correction factors were generated based on a multiple linear regression using a learning set consisting of 1290 organic compounds. The obtained linear regression model possesses good statistical significance with an overall correlation coefficient (r) of 0.96, a standard deviation (s) of 0.61, and an unsigned mean error (UME) of 0.48. The actual prediction potential of the model was validated through an external test set with 21 pharmaceutically and environmentally interesting compounds. For the test set, a predictive r 0.94, s 0.84, and UME 0.52 were achieved. Comparisons among eight procedures of solubility calculation for those 21 molecules demonstrate that our model bears very good accuracy and is comparable to or even better than most reported techniques based on molecular descriptors. Moreover, we compared the performance of our model to a test set of 120 molecules with a popular group contribution method developed by Klopman et al. For this test set, our model gives a very effective prediction (r 0.96, s 0.79, UME 0.57), which is obviously superior to the predicted results (r 0.96, s 0.84, UME 0.70) given by the Klopman's group contribution approach. Because of the adoption of atoms as the basic units, our addition model does not contain a “missing fragment” problem and thus may be more simple and universal than the group contribution models and can give predictions for any organic molecules. A program, drug-LOGS, had been developed to identify the occurrence of atom types and estimate the aqueous solubility of a molecule.

The spin-dependence of the interface resistance between ferromagnetic Fe and InAs is calculated from first-principles for specular and disordered (001) interfaces. Because of the symmetry mismatch in the minority-spin channel, the specular interface acts as an efficient spin filter with a transmitted current polarisation between 98 an 89%. The resistance of a specular interface in the diffusive regime is comparable to the resistance of a few microns of bulk InAs. Symmetry-breaking arising from interface disorder reduces the spin asymmetry substantially and we conclude that efficient spin injection from Fe into InAs can only be realized using high quality epitaxial interfaces.

Abstract: The shear and principal strains involved in equal channel angular deformation (ECAD) were analyzed using a variety of methods. A general expression for the total shear strain calculated by integrating infinitesimal strain increments gave the same result as that from simple geometric considerations. The magnitude and direction of the accumulated principal strains were calculated based on a geometric and a matrix algebra method, respectively. For an intersecting angle of π/2, the maximum normal strain is 0.881 in the direction at π/8 (22.5 deg) from the longitudinal direction of the material in the exit channel. The direction of the maximum principal strain should be used as the direction of grain elongation. Since the principal direction of strain rotates during ECAD, the total shear strain and principal strains so calculated do not have the same meaning as those in a strain tensor. Consequently, the “equivalent” strain based on the second invariant of a strain tensor is no longer an invariant. Indeed, the equivalent strains calculated using the total shear strain and that using the total principal strains differed as the intensity of deformation increased. The method based on matrix algebra is potentially useful in mathematical analysis and computer calculation of ECAD.

The dynamic light scattering technique is employed to study the self-assembling behavior of Nafion in dilute aqueous solutions and in water-based mixture solvents. The mixture solvents contain either salt or a small amount of glycerol, which is often necessary for the fabrication of the electrode−membrane assembly. Two kinds of aggregates are found in Nafion aqueous solutions:  (1) an intrinsic aggregate (~150 nm) due to the hydrophobic interaction of fluorocarbon backbone, which is found to be always present in aqueous solutions; (2) a larger, secondary aggregate, which can be suppressed by the addition of salt or a small amount of glycerol. This secondary/higher level aggregation may arise from the electrostatic attraction through the nonionized ion pairs, which are believed to facilitate the formation of large ion clusters and provide the ion connection between the ion clusters. We discuss the structures of Nafion aggregates based on the rodlike microstructure units and propose a microgel-type aggregation model.

An incoherent dynamic light-scattering technique is developed to measure the local velocity and its statistics. By employing two parallel laser beams of different colors, the technique measures the cross-correlation function of the scattered intensities from two separate illuminating volumes. Because there is no phase coherence between the two laser beams, the measured cross-correlation function is sensitive only to the intensity fluctuations caused by a seed particle that crosses the two beams in succession. The flow velocity is obtained from the measured particle transit time. We frame the scattering theory so as to account for the two-beam scattering geometry. Our experiment verifies the calculation and demonstrates applications of the technique. The method has the unique feature of being able to measure simultaneously the local velocity in two opposite directions perpendicular to the incident laser beams. Its advantages are high spatial resolution and accuracy, fast temporal response, and ease of use. The technique is useful in studies of turbulent flows, sedimentation of heavy particles, and flow phenomena in complex fluids.

Sulfur K‐edge x‐ray absorption near‐edge structure spectroscopy (XANES) was used to identify multiple organic S oxidation states in aquatic and soil humic substances. The XANES results suggest that S in humic substances exists in four major oxidation groups similar to sulfate ester, sulfonate, sulfoxide, and thiol‐sulfide. Thiol S cannot be separated from sulfide S and must be considered as a single thiol‐sulfide peak. The second derivative spectra suggest the existence of thiophene and sulfone S. The relative quantities of each major S form in our humic samples were estimated based on the integrated cross section of each s → p transition peak corresponding to different S oxidation states in the S K‐edge XANES spectra. The XANES results of the four humic samples used in this study appear to reflect the environmental settings where the humic substances originally formed. The percentage of the most reduced organic S (thiol‐sulfide and possibly thiophene) in humic substances follows the sequence: aquatic samples > organic soil sample > mineral soil sample. The percentage of most oxidized S (sulfate group) was the greatest in the humic substance from a mineral soil and the lowest in the aquatic humic substances.

The herpes simplex virus ICP4 protein is required for induction of early and late viral gene transcription as well as for repression of expression of its own gene and several other viral genes. Several electrophoretic forms of ICP4 have been observed, and phosphorylation is thought to contribute to this heterogeneity and possibly to the multiple functions of ICP4. To define the complexity of the site(s) of phosphorylation of ICP4 and to initiate mapping of this site(s), we have performed two-dimensional phosphopeptide mapping of wild-type and mutant forms of ICP4 labeled in infected cells or in vitro. Wild-type ICP4 labeled in infected cells shows a complex pattern of phosphopeptides, and smaller mutant forms of ICP4 show progressively fewer phosphopeptides, arguing that multiple sites on ICP4 are phosphorylated. The serine-rich region of ICP4, residues 175 to 198, was shown to be a site for phosphorylation. Furthermore, the serine-rich region itself or the phosphorylation of this region increases phosphorylation of all phosphopeptides. A mutant ICP4 molecule lacking the serine-rich region showed low levels of phosphorylation by protein kinase A or protein kinase C in vitro. These results suggest that there may be a sequential phosphorylation of ICP4, with phosphorylation of the serine-rich region stimulating phosphorylation of the rest of the molecule. In addition, purified ICP4 showed an associated kinase activity or an autophosphorylation activity with properties different from those of protein kinase A or protein kinase C.

Efficient expression of herpes simplex virus genes requires the synthesis of functional ICP4, a nuclear phosphoprotein that contains a prominent serine-rich region between amino acids 142 and 210. Residues in this region not only are potential sites for phosphorylation but also are involved in the functions of ICP4. By comparing the growth of a virus in which this region is deleted (d8-10) with wild-type virus (KOS) in PC12 cells or PC12 cells that are deficient in cyclic AMP-dependent protein kinase (PKA), two observations were made: (i) the growth of wild-type virus was impaired by 1 to 2 orders of magnitude in the PKA-deficient cells, indicating the involvement of PKA in the growth cycle of herpes simplex virus type 1, and (ii) while the growth of d8-10 was impaired by almost 2 orders of magnitude in wild-type cells, it was not further impaired (as was that of wild-type virus) in PKA-deficient cells, implicating the region deleted in d8-10 as a possible target for cellular PKA. In trigeminal'ganglia of mice, the d8-10 mutant virus grew poorly; however, it established latency in nearly 90% of ganglia tested. Studies of the phosphorylation of wild-type and d8-10 ICP4 proteins revealed that the serine-rich region is a major determinant for phosphorylation of ICP4 in vivo and that the phosphorylation state could change as a function of the PKA activity. Consistent with this observation, the serine-rich region of ICP4 was shown to be a target for PKA in vitro. While intact ICP4 was readily phosphorylated by ICP4 in vitro, the d8-10 mutant ICP4 was not. Moreover, a synthethic peptide representing a sequence in the serine tract that is predicted to be a substrate for PKA was phosphorylated by PKA in vitro, having a Km within the physiological range. These data suggest that PKA plays a role in viral growth through phosphorylation of one or more sites on the ICP4 molecule.

The magnetic properties of sputtered Co/Pb multilayers have been studied by vibrating-sample magnetometer (VSM), torque magnetometer and ferromagnetic resonance spectroscopy (FMR). Magnetic measurements show that with decreasing Pb layer thickness the perpendicular anisotropy field Hu increases from 5.7 to 8.3 kOe. The interfacial anisotropy is obtained to be as small as Ks = 0.006 erg/cm2. It is demonstrated that the increase of Hu with decreasing Pb layer thickness is due to the variation of texture in h.c.p. Co along the [00.2] direction with spacer thickness. The in-plane magnetic hysteresis loops show a higher saturation field and smaller remanence ratio for thin spacer films which cannot be accounted for solely by Hu and indicates the existence of antiferromagnetic (AFM) coupling between Co layers through Pb spacer. The interlayer coupling is also implied by the observation of spin wave resonance (SWR) in perpendicular FMR. From the SWR spectrum the effective exchange constant is obtained as IiAeff = 3.4×10—7 erg/cm. A resonance peak appears on the high-field side of the uniform FMR mode, which is attributed to the AFM coupling of adjacent ferromagnetic layers producing an “optical” mode. The Pb layer thickness (tPb) dependence of the separation of the resonance fields, ΔH, between the optical mode and uniform mode in the perpendicular FMR spectrum is fitted by ΔH = 2.80 exp (—(tPb — 1))/1.78 (kOe) with a characteristic thickness of 1.78 nm. Thus, the coupling strength (IiJ = iiMstCoΔH/2), in proportion to ΔH, decreases exponentially with Pb layer thickness, which is consistent qualitatively with the variation of the in-plane remanence ratio with spacer thickness.

High temperature mechanical properties of discontinuous, whisker and particulate, SiC reinforced aluminum composites, including 2124 and 6061 alloy matrices, are reviewed. It is shown that the behavior of these composites is similar to conventional oxide dispersion strengthened alloys. Namely, they exhibit a low strain rate senstivity and a high apparent activation energy for creep deformation. Despite the fact that the addition of SiC significantly improves the mechanical properties of aluminum at room temperature, the mechanical strength of the composite at elevated temperatures is dominated by the strength of the aluminum matrix This is because the SiC dispersoids are, in general, too coarse and they are not effective barriers for dislocation motion. It is also demonstrated that SiC particulate composites are less creep resistant than SiC whisker composites.