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High-quality Japanese swords display a pattern just below the spine called the utsuripattern. The physical mechanism causing this pattern remains a mystery. An hypothesis is presented here postulating that the pattern is produced by a transition in the microstructure from pearlite to the product microstructure of the divorced eutectoid transformation, DET. Experiments are presented in which such a transition was produced on small blade pieces. It is demonstrated that the contrast on these blades is adequate to produce the utsuripatterns.

Experiments on the divorced eutectoid transformation, DET, in eutectoid steel have produced the following conclusions. The maximum rate of continuous cooled steel that produces the DET rather than the pearlite eutectoid transformation, PET, is 0.7 ± 0.4 °C/s. The product microstructure of the DET is not just spheroidite but rather regions of three different microconstituents which will be labeled F, L and S. The F regions consist of pure ferrite, L regions, a coarse lamellar pearlite and S regions spheroidite. The product of the DET is strongly influenced by the initial microstructure of the steel; starting with spheroidite generally produces a spheroidite product while starting with pearlite produces the F, L, S product. In the L regions, the pearlite-like structures are growing into a ferrite matrix; experiments show that the pearlite growing into austenite at 700 °C is finer and harder than that growing into the ferrite during a DET at 700 °C Experiments were done on commercial steels containing levels of carbide forming elements of 900 ppmw. Similar experiments on a high-purity steel found a significant increase in the arrest temperature of the DET and decrease in hardness of the DET product; this result is postulated to be due to a combination of reduced amounts of carbide forming elements as well as S and P in the high-purity steel. Finally, hypotheses are presented for the cause of these results along with possible models.

A review is presented of the steels used to produce perhaps the two most famous swords in history, the Japanese sword and the Muslim crucible Damascus sword. The review is based largely on the authors experience in producing blades of these materials, bloomery steel blades by T.Z., and crucible Damascus blades by J.V. and the late bladesmith Alfred Pendray. Brief summaries are presented of the history of when and how the swords were made, our modern understanding of their metallurgical microstructures, their chemical composition, relative strength, resistance to breakage (toughness) and ability to hold an edge. Both swords were superior to the more ancient swords they competed with. All were made from bloomery iron. A smelted bloom contains large amounts of slag inclusions and varying amounts of carbon. The slag inclusions reduced the toughness of the ancient steel and the non-uniform carbon composition of the bloom produced wide variations in strength. It is explained how these deficiencies were overcome in the production of both swords. Comparing the properties of the sword microstructures after processing them to shape, it is concluded that the Japanese sword was superior.

When a smith heats a metal bar, an austenite front, Af, advances into the bar. Experiments show the following: [1] A significant shift occurs in the location of the Affront on the observed color bands formed on a heat-up versus a cool-down experiment. [2] The resulting microstructure produced from the austenite zone extending from the hot end to the Affront for three different cooling rates: (a) quenching in water; (b) cooling at an intermittent rate too fast to allow the transformation to occur by the divorced eutectoid transformation (DET) mode and too slow to produce bainite or martensite; and (c) cooling slow enough for the eutectoid transformation to occur by the DET mode rather than the PET mode, pearlite eutectoid transformation. Experiments were done confirming a previous study showing that when starting with pearlite the product of the DET is a mixture of ferrite, coarse pearlite, and spheroidite, whereas starting with a spheroidite it is spheroidite.

Background: After a transient ischemic attack (TIA) or minor stroke, the long-term risk of subsequent stroke is uncertain. Methods: Electronic databases were searched for observational studies reporting subsequent stroke during a minimum follow-up of 1 year in patients with TIA or minor stroke. Unpublished data on number of stroke events and exact person-time at risk contributed by all patients during discrete time intervals of follow-up were requested from the authors of included studies. This information was used to calculate the incidence of stroke in individual studies, and results across studies were pooled using random-effects meta-analysis. Results: Fifteen independent cohorts involving 129794 patients were included in the analysis. The pooled incidence rate of subsequent stroke per 100 person-years was 6.4 events in the first year and 2.0 events in the second through tenth years, with cumulative incidences of 14% at 5 years and 21% at 10 years. Based on 10 studies with information available on fatal stroke, the pooled case fatality rate of subsequent stroke was 9.5% (95% CI, 5.9 – 13.8). Conclusions: One in five patients is expected to experience a subsequent stroke within 10 years after a TIA or minor stroke, with every tenth patient expected to die from their subsequent stroke.

We provide a case analysis for a 28-year-old, native Dutch-speaking lady who developed Foreign Accent Syndrome (FAS), a few weeks after falling down the staircase. In addition to FAS, which gave the impression she spoke with a German accent, German(-like) words and structures occurred. Speech symptoms were aggravated by increased stress, fatigue or emotional pressure, and this triggered jargon speech. It was hypothesized her FAS and jargon developed on a functional basis.

Alterations in cellular aging, indexed by leukocyte telomere length (LTL) and mitochondrial DNA copy number (mtDNAcn), might partly account for the increased health risks in persons with depression. Although some studies indeed found cross-sectional associations of depression with LTL and mtDNAcn, the longitudinal associations remain unclear. This 10-year longitudinal study examined between- and within-person associations of depressive symptoms with LTL and mtDNAcn in a large community sample. Data are from years 15, 20 and 25 follow-up evaluations in 977 subjects from the Coronary Artery Risk Development in Young Adults study. Depressive symptoms (years 15, 20, 25) were assessed with the Center for Epidemiologic Studies Depression (CES-D) scale; LTL (years 15, 20, 25) and mtDNAcn (years 15, 25) were measured in whole blood by quantitative PCR. With mixed-model analyses, we explored between- and within-person associations between CES-D scores and cellular aging markers. Results showed that high levels of depressive symptomatology throughout the 10-year time span was associated with shorter average LTL over 10 years (B=-4.2; P=0.014) after covarying for age, sex, race and education. However, no within-person association was found between depressive symptoms and LTL at each year (B=-0.8; P=0.548). Further, we found no between-person (B=-0.2; P=0.744) or within-person (B=0.4; P=0.497) associations between depressive symptomatology and mtDNAcn. Our results provide evidence for a long-term, between-person relationship of depressive symptoms with LTL, rather than a dynamic and direct within-person relationship. In this study, we found no evidence for an association between depressive symptoms and mtDNAcn.

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To report the estimated incidence, probability, risk factors, and 1-year outcomes of rhegmatogenous retinal detachment (RRD) in eyes receiving intravitreal injections (IVTs) of VEGF inhibitors for various retinal conditions in routine clinical practice.

The combination of nanosecond transient absorption experiments and single photon timing experiments proved the occurrence of an electron transfer process in the triphenyl amine core dendrimer, N1P1, by demonstrating the presence of an ion-pair absorption for N1P1in solvents of medium polarity. By means of femtosecond transient absorption measurements the rise time of this ion-pair absorption dominated by the radical anion absorption could be determined, resulting in a value of 180 ps in MeTHF and 138 ps in THF. Furthermore, in femtosecond fluorescence upconversion as well as in monochromatic femtosecond transient absorption, a few ps component was resolved which was assigned to a vibrational and solvent relaxation process of the locally excited singlet state of the peryleneimide.

The combination of nanosecond transient absorption experiments and single photon timing experiments proved the occurrence of an electron transfer process in the triphenyl amine core dendrimer, N1P₁, by demonstrating the presence of an ion-pair absorption for N1P₁ in solvents of medium polarity. By means of femtosecond transient absorption measurements the rise time of this ion-pair absorption dominated by the radical anion absorption could be determined, resulting in a value of 180 ps in MeTHF and 138 ps in THF. Furthermore, in femtosecond fluorescence upconversion as well as in monochromatic femtosecond transient absorption, a few ps component was resolved which was assigned to a vibrational and solvent relaxation process of the locally excited singlet state of the peryleneimide.

The combination of nanosecond transient absorption experiments and single photon timing experiments proved the occurrence of an electron transfer process in the triphenyl amine core dendrimer, N1P1, by demonstrating the presence of an ion-pair absorption for N1P1in solvents of medium polarity. By means of femtosecond transient absorption measurements the rise time of this ion-pair absorption dominated by the radical anion absorption could be determined, resulting in a value of 180 ps in MeTHF and 138 ps in THF. Furthermore, in femtosecond fluorescence upconversion as well as in monochromatic femtosecond transient absorption, a few ps component was resolved which was assigned to a vibrational and solvent relaxation process of the locally excited singlet state of the peryleneimide.

The behavior is reported of three fluorescent D−bridge−A systems that display a fascinating temperature dependence in glass forming solvents over the temperature range between 77 and 293 K. In two of these systems, a rigid, saturated alkane bridge maintains an extended conformation, and as a result, the charge-transfer (CT) state is of giant dipolar nature. This causes the position of the CT fluorescence to be an extremely sensitive probe for the reorientation polarization of the surrounding medium. As a result, the thermochromism of the continuous CT fluorescence maximum in 2-methyltetrahydrofuran (MTHF) covers the full visible region. In the higher temperature domain (above ca. 145 K), this thermochromism can be quantitatively described via the Lippert−Mataga relation. At lower temperatures, solvent relaxation slows down sufficiently to detect exceptionally large dynamic Stokes shifts of the fluorescence maximum on time scales up to ≥40 ns. The third D−bridge−A system studied features a U-shaped ground state conformation. Remarkably, this system displays a significant thermochromic shift over a narrow temperature region around 175 K in the nonpolar methylcyclohexane (MCH) in which the other systems display only very minor thermochromism. In this U-shaped system therefore, one monitors the temperature dependence of an internal reorganization instead of a medium relaxation. Extensive ab initio calculations indicate that this internal reorganization must be related to an electrostatically driven conformational collapse of the U-shaped system in the CT state.

Efficient intramolecular triplet−triplet energy transfer from an N,N-dialkylanilino donor to an alkene acceptor was observed in 4-(4-(propan-2-ylidene)cyclohexyl)-N,N-dimethylaniline (2) and 1-phenyl-4-cyclohexylidenepiperidine (4) using nanosecond transient absorption spectroscopy and time-resolved microwave conductivity. This enables the unequivocal assignment of the absorption spectrum of the first singlet excited state of the N,N-dialkylanilino chromophore in 4-cyclohexyl-N,N-dimethylaniline (1), 2, 1-phenyl-4-cyclohexylpiperidine (3) and 4. It has a maximum positioned between 600 and 635 nm.

The photoinduced intramolecular electron transfer in two donor−bridge−acceptor systems was studied using (time-resolved) fluorescence and transient absorption techniques. DPN[8cy]DCV and DPMN[8cy]DCV consist of a 1,4-diphenylnaphthalene (DPN) and a 1,4-diphenyl-5,8-dimethoxynaphthalene (DPMN) electron donor, respectively, and the 1,1-dicyanovinyl acceptor (DCV) in both systems. The overall geometry of the saturated hydrocarbon bridge is U-shaped, separating the donor and acceptor by an 8-σ-bond through-bond distance and a 5.8 Å (center-to-center) through-space distance in the ground state. In all solvents fast electron transfer is observed in both systems resulting in a fluorescent charge transfer (CT) state. Especially for DPN[8cy]DCV CT fluorescence can be detected over a wide range of solvent polarity. The solvent dependence of the CT fluorescence position, lifetime, and quantum yield could thus be employed to estimate the solvent effect on the dipole moment of the CT state, the rate of charge recombination, and the electronic coupling (V) between donor and acceptor. It is concluded that in the (luminescent) CT state both the distance between donor and acceptor and their electronic coupling are virtually solvent independent, which excludes a solvent-mediated electron-transfer pathway. Gas phase (U)HF ab initio MO calculations carried out on the model molecule DMN[8cy]DCV (which contains a computationally less demanding 1,4-dimethoxynaphthalene donor) predict that the center-to-center distance between the two chromophores in the CT state is about 4.4 Å which amounts to a 1.4 Å contraction with respect to the ground state geometry. The degree of contraction is almost entirely due to pyramidalization at the DCV radical anion site and occurs in the direction of the dimethoxynaphthalene radical cation for electrostatic reasons. The calculated weak out-of-plane bending potential associated with this pyramidalization implies that the degree and direction of pyramidalization in the CT state of the DCV moiety can be preserved in solution and that it is fairly insensitive toward solvent polarity as shown by the results of UHF/6-31G(d) continuum solvation calculations and as supported by the experimental results for DPN[8cy]DCV. The small and constant D/A separation in the CT state also explains the experimentally found constancy of the electronic coupling, which must be of a direct through-space (TS) nature because no solvent molecules can be accommodated between D and A. Remarkably, while the charge recombination in DPMN[8cy]DCV displays the strong rate enhancement with increasing solvent polarity typical for charge recombination occurring under “inverted region conditions”, the rate of charge recombination in DPN[8cy]DCV is virtually constant over a wide range of solvent polarities. This very unusual behavior appears to be related to the presence of parallel charge recombination pathways to respectively the ground state and to a local triplet state with an opposite solvent dependence of their rate.

Abstract: Austenite containing fine particles of carbides may undergo the eutectoid transformation by either the pearlite reaction or the divorced eutectoid transformation (DET) reaction. The latter reaction automatically produces a spheroidized structure, while the pearlite reaction produces a structure that resists spheroidization. This study has evaluated the heat treatment conditions that promote the DET in 52100 steel. The results show that the DET is dominant over the pearlite reaction for austenitization at temperatures of 830 C and below and for cooling rates of 500 C/h and below. This information should be useful in the design of more energy efficient heat treatment processes for spheroidization annealing than the very long time processes currently recommended in the literature.

Thin polycrystalline B-doped diamond films on Si, prepared by microwave plasma chemical vapour deposition, were diagnosed by means of secondary electron emission measurements. Investigations, including caesium deposition, were carried out on a hydrogen and an oxygen-terminated sample cut from the same wafer. Caesiation resulted in a mean secondary electron emission factor 〈δ∗〉 at a primary electron energy Ep=1800eV equal to 76 and 63 on the H- and O-terminated sample, respectively. Due to electron stimulated desorption, the secondary emission decreased to 〈δ∗〉≈45 on both samples under irradiation to a level of ∼1C/cm2. On the caesiated samples the reduction of δ∗with electron dose was not local, but occurred over the whole surface because of the diffusion of Cs to the irradiated spot.

Charge-transfer fluorescence probes show a strong response of the intensity and wavelength positions of their spectra to solvent polarity and mobility. Such properties have been applied in the past to follow polymerization kinetics and solvent-induced effects (e.g., swelling) in polymeric materials. An important advantage of charge-transfer fluorescence probes is that they can be measured at extremely low concentrations, hence interference with the polymeric system is limited. Furthermore they report from “within,” since they are only sensitive to phenomena which occur in their immediate surroundings. In this paper it is shown that charge-transfer fluorescence probes can also be applied to study mechanical and thermal properties of polymers. The charge-transfer fluorescence probe Fluoroprobe (1-phenyl-4-[(4-cyano-1-naphthyl)methylene]piperidine) was doped into a polyether–polyester block copolymer, which was submitted to thermal and mechanical stress. The effect of strain applied to the polymers in various forms (fibers, sheets) and the effect of thermal processes (glass transition temperatures, phase transitions, melting points) are clearly reported by the changes in fluorescence intensity and wavelength of the Fluoroprobe molecule.

Rare earth ions, with relatively long luminescence lifetimes, have significant advantages for application in fields as varied as diagnostics and optical amplification. In diagnostics the long luminescence lifetimes allow for extremely sensitive time-gated detection, where the difference in temporal behavior of scatter and background fluorescence and the long-lived rare earth luminescence is utilized. In optical amplification the long excited-state lifetime makes it easier to obtain population inversion, a requirement for effective stimulated emission. Unfortunately the absorption cross section of rare earth ion transitions is extremely low. However, via sensitized excitation by means of a suitable organic molecule, efficient excitation is obtained. It is shown that excitation in the visible part of the spectrum can be used to excite rare earth ions which luminesce in the near-IR, such as ytterbium, neodymium, and erbium, via a fluorescein-derivative as sensitizer. The advantages of this approach are manifold. Low-cost light sources are available for the visible part of the spectrum, and interferences from the matrix (scatter, absorption) are minimal. Detection in the near-IR is almost interference-free. For optical amplification the wavelength regions around 1300 and 1550 nm, which can be covered with the neodymium and erbium complexes, respectively, are the most important for applications in optical telecommunication.

The fluorescence of four semiflexibly bridged donor−bridge−acceptor systems was studied with a streak camera system. The information-rich streak data make a detailed analysis possible of both the kinetics and the spectral changes that take place. From the analysis, it follows that all compounds studied undergo a photoinduced harpooning process in which long-range electron transfer creates an extended charge-transfer (ECT) species, which converts to a compact charge-transfer (CCT) species due to Coulombic attraction. Both the ECT and CCT species display CT fluorescence. The harpooning process occurs even in solvents of medium polarity (e.g., diethyl ether), whereas it has previously been assumed for related compounds that this process only occurs in the gas phase and in nonpolar alkane solvents.

Experimental evidence is presented which indicates that the Nb3Sn filaments withinin situ prepared Nb3Sn-Cu superconducting wire are welded together at point contacts along a thin annular region which borders the surface of the original tin supply. For wires with tin added from an external plated layer the welded annular region lies near the outside diameter just below the original tin plate, whereas for wires with the tin added from an internal core the annular region lies along the original core hole. This welded region is expected to increase the a.c. loss characteristics of these wires. A possible cause of the welded annular region and methods for its elimination are discussed.

Heavily drawn Cu-Nb alloys display quite high ultimate tensile strengths. A modification to the consumable arc-casting technique used to prepare these alloys is shown to decrease the as-cast niobium dendrite diameter,t0, and also increase strength. Evaluation of strength, niobium filament spacing and thickness data show that strength varies with as-cast niobium dendrite size as somewhere betweento-0.36 toto-0.50. Splat-cooling techniques demonstrate that minimum niobium dendrite sizes as small as 0.22µm are possible. These sizes are over a factor of 10 smaller than has been achieved by consumable arc casting, and it is therefore suggested that processing rapidly solidified powders of Cu-Nb alloys should have significant advantages for preparing high-strength heavily drawn Cu-Nb alloys.

Alloys of Cu-Fe with iron contents from 10 to 30 wt % have been prepared by casting plus mechanical reduction. A series of heat treatments was done at various stages of the mechanical reduction to promote precipitation of the iron from the copper matrix with the hope of optimizing electrical conductivity at a given strength level. A curve of optimum tensile strength against electrical conductivity was determined. It was found to lie significantly below the available data for Cu-Nb alloys and it is suggested that further improvements may be possible in Cu-Fe alloys by improved thermal mechanism processing.

Abstract: Powder metallurgical techniques have been employed to prepare the precursor billets in the preparation of Cu-15 vol pct Fe alloys by deformation processing. It has been demonstrated that by (1) using high-purity gas-atomized Cu powders blended with commercial high-purity Fe powders and (2) controlling the time/temperature processing conditions within specific limits, it is possible to produce Cu-Fe deformation-processed alloys with strength/conductivity properties matching those of Cu-Nb, Cu-Ta, and Cu-Cr alloys. These properties are significantly superior to the best commercial alloys.

Abstract: A Cu-5 pct Nb alloy was deformation processed by wire drawing to very large reductions (99.9993 pct) and the strength and electrical conductivity properties compared with similarly deformation processed Cu-20 pct Nb. The results showed that the Cu-5 pct Nb alloy was transformed into a composite material with the original Nb dendrites becoming ribbonlike filaments in a similar fashion to higher Nb-containing Cu-Nb alloys. The degree of strength increase with increasing deformation processing greatly exceeds rule-of-mixtures expectations at higher degrees of deformation processing, where the Nb becomes highly aligned with the wire axis. A 5 pct Nb addition appears to contain close to the minimum amount of Nb phase necessary to produce appreciable strengthening during deformation processing of Cu-Nb alloys. The strength-conductivity properties of the deformation-processed Cu-5 pct Nb alloy show significant improvements in strength over the best commercial alloys in the conductivity range of 80 to 90 pct international annealed copper standard (IACS).

Abstract: Directional solidification techniques have been developed to produce grain-aligned rods of the highly magnetostrictive material Terfenol-D, TbxDy1-xFey The magnetostrictive properties have been compared to those of single-crystal, bicrystal, and polycrystal rod prepared by a float zone melting (ZM) technique. It was found that the properties of the grain-aligned material were comparable to three-and four-grain ZM material and the magnetostriction for both materials was less than the ZM single crystal and the better bicrystal rods by around 20 pct. It was demonstrated that a heat treatment consisting of a 1-hour hold at 950 �C was very effective at improving the magnetostrictive properties of all of the materials. Experiments have demonstrated that, to be effective, the heat-treatment temperature must be above somewhere between 850 �C and 900 �C. It is postulated that the mechanism for the improved properties involves a relief or redistribution of residual stresses produced by localized melting near second-phase particles at the predicted eutectic temperature of around 875 �C in the Terfenol-D material.

The forced velocity pearlite data of Part I is compared to the Zener-Hillert treatment and shown to fit the volume diffusion model but requires aDvalue higher than that of the Wells’etal.16data by a factor of 3 to 4. It is postulated that the highDvalue is due to a strain in the austenite phase at the growth front. It is found that inclusion of a mobility term, μ, in the Zener-Hillert analysis requires a quadratic form,V= μΔ2, in order to fit the data. Additional experiments have shown that the degenerate pearlite found at high growth velocities results from coarsening of fine pearlite as it cools from the growth front temperatures. Finally, some speculations are offered to explain the various interesting growth features of pearlite presented in Part I.

An experimental technique was developed to measure the interface temperature of directionally transformed pearlite. It was shown that the growth temperature of such forced velocity pearlite is the same as the growth temperature of isothermally formed pearlite which grows at the same velocities. It was also shown that forced velocity pearlite is kinetically limited to maximum growth rates of around 100 μm per second. It was demonstrated that a small but significant fraction of prior austenite grain boundaries interferes with pearlite growth by halting the growth of the cementite lamellae. Velocityvsspacing data were found to fit an equation of the formV ∝ S-nwithn =2.07. Arguments are presented which indicate that previous literature values ofn= 2.4 and 2.7 may be high due to experimental difficulties.

Abstract: The effect of Ta additions on the critical currents,J c , and upper critical fields,H C2 , ofin situ prepared Nb3Sn-Cu superconducting wires has been examined. It was found that the Ta segregates virtually completely to the Nb dendrites and causes no observable change in the Nb3Sn filament morphology. Both high fieldJ c andH* c2 values increase to a maximum at 10 wt pct Ta in the Nb-Ta phase and then drop for higher Ta contents. The improvement inJ c in the 12 to 16T range, however, is small. TheJ c values ofin situ wires are equivalent to bronze processed wires up to12T, but above that value they become significantly lower.

Abstract: Vertical solidification experiments have been carried out on Pb-Sn and Pb-Cd alloys at hypereutectic compositions where solute convection was present. A significant amount of macrosegregation was observed due to the convection, and the macrosegregation was found to be independent of tube diameter for those diameters studied, 3 to 6 mm. The resulting macrosegregation correlated well with existing theories. The experiments employed a temperature gradient of 360°C/cm and it was found that thermotransport made a significant contribution to the observed macrosegregation at growth rates below around 5 μm/s.

Abstract: Steady state solidification experiments were carried out on Sn−Bi alloys of compositions from zero to 3.5 at. pet Bi with tube diameters from 1.9 to 5 mm. Solute profiles were determined utilizing a radioiostope, Bi207, and a microtome slicing technique. Results indicate the technique offers a relatively precise method for determining liquid metal diffusion coefficients at the solidus temperature. Convection does not appear to be a problem for tube diameters under 3 mm. It is shown that neglect of thermal transport may give errors in the measured diffusion coefficients as high as 10 to 30 pet.