The aim of this study was to characterize detailed interfacial microstructures and evaluate tensile properties of Al6061-to-Cu dissimilar welded joints via electromagnetic pulse welding (EMPW) at ...different discharge voltages. The EMPWed joints consisted of annular weld zone and central non-weld zone. The outer and inner regions of annular weld zone exhibited mainly diffusion bonding and mechanical interlocking, respectively, representing a well-bonded interface. Distinctive discontinuous “droplet-like” pseudo-eutectic (α-Al + Al2Cu) particles or patches were observed to eject in the adjacent transition region in the non-weld zone. The highly non-equilibrium eutectic-like liquid or slurry at the Al/Cu interface was formed due to the ultra-high strain rate experienced by the interface and the ensuing instant temperature rise beyond the eutectic temperature of Al–Cu system, when the high-velocity flyer Al sheet crashed into the fixed Cu sheet driven by the Lorentz force during EMPW. The interfacial diffusion layer was thin in the order of 1–2 μm. The higher the discharge voltage was, the more obvious the interfacial diffusion layer and mechanical interlocking were, with “wave-like” and “inverted hook-like” interfacial characteristics observed. While interfacial failure occurred during the tensile lap shear tests for the joints made at a discharge voltage of 12 kV, the failure loads were still significantly higher than those specified in the AWS D17.2 standard. The EMPWed joints made at 14 kV and 16 kV remained intact and only base metal failure occurred, with the tensile lap shear failure loads reaching over twice those specified in the AWS D17.2 standard. Thus the well-bonded robust Al/Cu dissimilar welds were successfully achieved via EMPW.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In order to establish an appropriate surface roughening procedure for obtaining high-quality surface Raman spectra from Pt electrodes, various roughening conditions for the SERS from the adsorbed ...pyridine, thiocynate and hydrogen are assessed in terms of the corresponding surface Raman intensities, enhancement factors and surface homogeneity. The repetitive square-wave oxidation reduction cycle (SWORC), triangular-wave ORC (TWORC) and platinization have been performed in the present study. The enhancement factor (
G) is calculated based on the confocal feature of a confocal microprobe Raman system, showing one to two orders of amplification of Raman signal for adsorbed pyridine on roughened Pt surfaces. The involvement of charge transfer (CT) enhancement is inferred from the SERS intensity-potential profiles that are dependent on excitation lines. In general, the Pt surfaces with different roughness factors (
R) can be divided into three categories: (1) the mildly roughened surface with
R of 20–30 seems more adequate for the study of SERS mechnism including calculation of
G; (2) the moderately roughened surface with
R ranging from 20 to 100, providing homogeneous morphologies, is suitable for investigating surface adsorption and reactions; (3) the highly roughened surface with
R ranging from 100 to 300, with non-uniform morphologies, could only be used for investigating species having small Raman cross-sections such as hydrogen adsorption.
Full text
Available for:
IJS, IMTLJ, KILJ, KISLJ, NUK, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
.
By using a multiple-scale method, we study the formation of the temporal ultraslow vector optical solitons (USVOS) in a cold lifetime-broadened five-level V type atomic system via ...electromagnetically induced transparency. And we find that the two orthogonally polarized components of the weak pulsed probe field can evolve into a pair of temporal USVOS. Subsequently, by numerical simulating the collision between two temporal USVOS, we obtain that their collision properties are correlated with their incident angle and initial phase shift. Whether two solitons are in phase or out of phase, their collisions are almost elastic. Especially, when two solitons are parallel input, the collisions between them are periodical. Our results may have potential application in optical information processing and engineering.
Full text
Available for:
DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
To analyse the clinical features and treatment strategies of papillary thyroid carcinoma(PTC) coexistent with lymphocytic thyroiditis (LT).
A total of 292 patients including 25 males and 267 females ...with LT and thyroid nodules treated in the department of head and neck surgery between Sep 2011 and Sep 2014 was analysed retrospectively and divided into two groups according to pathological results, of them 262 patients, with a median age of 47 years old, were LT with PTC and 30 patients, with a median age of 54 years old, were LT with benign nodules. Among 262 patients having LT with PTC, 259 were diagnosed as having malignant or suspicious malignant nodules and 3 having benign nodules with ultrasound before surgery, 98 cases were considered multifocal malignant nodules by preoperative ultrasound, and 112 cases were positive in cervical lymph nodes, including bilateral positive in 37 cases. Of 30 patients having LT with benign nodules, 14 were diagnosed malignant or suspicious malignant nodules and 16 benign no
Display omitted
•Robust ultrasonic spot welded Mg-Cu-Al tri-dissimilar joints are ably achieved.•Interface diffusion layer grows faster at Mg/Cu interface than at Al/Cu interface.•Distinctive ...barb-like interlock and core-shell structure occur at Al/Cu interface.•α-Mg + Mg2Cu eutectic structure is present at Mg/Cu interface at higher energies.•Failure occurs at Al/Cu interface (low energy) and Mg/Cu interface (high energy).
Ultrasonic spot welding of ZEK100-O Mg alloy to Al6022-T43 Al alloy with a Cu interlayer was successfully achieved, and relevant technical issues were investigated with focus on the microstructural evolution at Mg/Cu and Al/Cu interfaces and the tensile lap shear strength in relation to welding energy. While an interface diffusion layer occurred at both interfaces, the Mg/Cu interface diffusion layer mainly consisting of α-Mg and Mg2Cu eutectic structure grew much faster and became significantly thicker with increasing welding energy. A thin interface diffusion layer composed of primarily Al2Cu was present at the Al/Cu interface, alongside the formation of characteristic “barb”-like interlocks at lower energy levels and core-shell microstructures at higher energy levels. With increasing welding energy the tensile lap shear strength of the tri-dissimilar joints first increased, reached a peak value at an energy of 1500 J, and then decreased. The strength of ZEK100-Al6022 dissimilar joints was attained to be ∼35% higher with Cu interlayer than without Cu interlayer, reached ∼80% that of Al6022-Al6022 similar joints and almost the same strength level of ZEK100-ZEK100 similar joints. Interfacial failure was observed to occur at the Al/Cu interface at the lower energy and at the Mg/Cu interface at the higher energy.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We present a global comparison of differences in content of segmental duplication between human and chimpanzee, and determine that 33% of human duplications (> 94% sequence identity) are not ...duplicated in chimpanzee, including some human disease-causing duplications. Combining experimental and computational approaches, we estimate a genomic duplication rate of 4-5 megabases per million years since divergence. These changes have resulted in gene expression differences between the species. In terms of numbers of base pairs affected, we determine that de novo duplication has contributed most significantly to differences between the species, followed by deletion of ancestral duplications. Post-speciation gene conversion accounts for less than 10% of recent segmental duplication. Chimpanzee-specific hyperexpansion (> 100 copies) of particular segments of DNA have resulted in marked quantitative differences and alterations in the genome landscape between chimpanzee and human. Almost all of the most extreme differences relate to changes in chromosome structure, including the emergence of African great ape subterminal heterochromatin. Nevertheless, base per base, large segmental duplication events have had a greater impact (2.7%) in altering the genomic landscape of these two species than single-base-pair substitution (1.2%).
Full text
Available for:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Complex eukaryotic genomes are now being sequenced at an accelerated pace primarily using whole-genome shotgun (WGS) sequence assembly approaches. WGS assembly was initially criticized because of its ...perceived inability to resolve repeat structures within genomes. Here, we quantify the effect of WGS sequence assembly on large, highly similar repeats by comparison of the segmental duplication content of two different human genome assemblies. Our analysis shows that large (> 15 kilobases) and highly identical (> 97%) duplications are not adequately resolved by WGS assembly. This leads to significant reduction in genome length and the loss of genes embedded within duplications. Comparable analyses of mouse genome assemblies confirm that strict WGS sequence assembly will oversimplify our understanding of mammalian genome structure and evolution; a hybrid strategy using a targeted clone-by-clone approach to resolve duplications is proposed.
Full text
Available for:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We have analyzed gene expression in various brain regions of humans and chimpanzees. Within both human and chimpanzee individuals, the transcriptomes of the cerebral cortex are very similar to each ...other and differ more between individuals than among regions within an individual. In contrast, the transcriptomes of the cerebral cortex, the caudate nucleus, and the cerebellum differ substantially from each other. Between humans and chimpanzees, 10% of genes differ in their expression in at least one region of the brain. The majority of these expression differences are shared among all brain regions. Whereas genes encoding proteins involved in signal transduction and cell differentiation differ significantly between brain regions within individuals, no such pattern is seen between the species. However, a subset of genes that show expression differences between humans and chimpanzees are distributed nonrandomly across the genome. Furthermore, genes that show an elevated expression level in humans are statistically significantly enriched in regions that are recently duplicated in humans.
Biological research increasingly depends on 'finished' genome sequences. Deducing what is absent from these sequences is not trivial. More than 99% of the euchromatic portion of the human genome is ...now represented as a high-quality finished sequence with each base ordered and oriented. However, two principal types of gap remain: heterochromatic (estimated to be ∼200 Mb) and euchromatic (23.0 Mb) gaps. Here, we use various global sources of data to help understand the nature of the gaps in the finished human genome. Not all gaps are recalcitrant to subcloning, nor are most heterochromatic. The presence of recent segmental duplications is the most important predictor of gap location in euchromatic sequences. The resolution of these regions remains an important challenge for the completion of the human genome, gene annotation and SNP assignment.
Full text
Available for:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
PDF
