High critical temperature superconductors have zero power consumption and could be used to produce ideal electric power lines. The principal obstacle in fabricating superconducting wires and tapes is grain boundaries—the misalignment of crystalline orientations at grain boundaries, which is unavoidable for polycrystals, largely deteriorates critical current density. Here we report that high critical temperature iron pnictide superconductors have advantages over cuprates with respect to these grain boundary issues. The transport properties through well-defined bicrystal grain boundary junctions with various misorientation angles (θGB) were systematically investigated for cobalt-doped BaFe2As2 (BaFe2As2:Co) epitaxial films fabricated on bicrystal substrates. The critical current density through bicrystal grain boundary (JcBGB) remained high (>1 MA cm−2) and nearly constant up to a critical angle θc of ∼9°, which is substantially larger than the θc of ∼5° for YBa2Cu3O7–δ. Even at θGB>θc, the decay of JcBGB was much slower than that of YBa2Cu3O7–δ.

Traumatic brain injury caused by explosive or blast events is traditionally divided into four phases: primary, secondary, tertiary, and quaternary blast injury. These phases of blast-induced traumatic brain injury (bTBI) are biomechanically distinct and can be modeled in both in vivo and in vitro systems. The primary bTBI injury phase represents the response of brain tissue to the initial blast wave. Among the four phases of bTBI, there is a remarkable paucity of information about the cause of primary bTBI. On the other hand, 30 years of research on the medical application of shockwaves (SW) has given us insight into the mechanisms of tissue and cellular damage in bTBI, including both air-mediated and underwater SW sources. From a basic physics perspective, the typical blast wave consists of a lead SW followed by supersonic flow. The resultant tissue injury includes several features observed in bTBI, such as hemorrhage, edema, pseudoaneurysm formation, vasoconstriction, and induction of apoptosis. These are well-described pathological findings within the SW literature. Acoustic impedance mismatch, penetration of tissue by shock/bubble interaction, geometry of the skull, shear stress, tensile stress, and subsequent cavitation formation, are all important factors in determining the extent of SW-induced tissue and cellular injury. Herein we describe the requirements for the adequate experimental set-up when investigating blast-induced tissue and cellular injury; review SW physics, research, and the importance of engineering validation (visualization/pressure measurement/numerical simulation); and, based upon our findings of SW-induced injury, discuss the potential underlying mechanisms of primary bTBI.

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Josephson junctions were fabricated in epitaxial films of cobalt-doped BaFe 2 As 2 on [001]-tilt (La,Sr)(Al,Ta)O 3 bicrystal substrates. 10-µm-wide microbridges spanning a 30-degrees-tilted bicrystal grain boundary (BGB bridge) exhibited resistively-shunted-junction (RSJ)-like current-voltage characteristics up to 17 K, and the critical current was suppressed remarkably by a magnetic field. Microbridges without a BGB did not show the RSJ-like behavior, and their critical current densities were 20 times larger than those of BGB bridges, confirming BGB bridges display a Josephson effect originating from weakly-linked BGB.

DC superconducting quantum interference devices (dc-SQUIDs) were fabricated in Co-doped BaFe 2 As 2 epitaxial films on (La, Sr)(Al, Ta)O 3 bicrystal substrates with 30° misorientation angles. The 18 × 8 µm 2 SQUID loop with an estimated inductance of 13 pH contained two 3 µm wide grain boundary junctions. The voltage-flux characteristics clearly exhibited periodic modulations with ∆V = 1.4 µV at 14 K, while the intrinsic flux noise of dc-SQUIDs was 7.8 × 10 -5 Φ 0 /Hz 1/2 above 20 Hz. The rather high flux noise is mainly attributed to the small voltage modulation depth which results from the superconductor-normal metal-superconductor junction nature of the bicrystal grain boundary.

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A NEW ALDEHYDE SYNTHESIS via DIMETHYLAMIDES 1089 ~* O D 1.4042, and 2.5 g., 8.57, yield, of capronitrile, b . p . 73" a t 53-55 m m . , n z O~ 1,4070.C. Cyclohexanecarbonitrile.-Cyclohexanecarboxaldehyde, b.p. 63-66" a t 23-24 mm., n % 1.4507, was obtained in 71y0 yield.D . Benzonitri1e.-Benzaldehyde, b . p . 81-82' a t 31 mm., RZoD 1.5452, was obtained in 767? yield. E. p-Chlorobenzonitri1e.-Lithium triethoxyaluminohydride (0.238 mole) was prepared in 238 ml. of ether. Into this stirred solution was added 32.7 g . (0.238 mole) of p-chlorobenzonitrile all a t once a t ice-bath temperature. The reaction mixture was hydrolyzed, after an hour, with 200 ml. of 5 i V sulfuric acid.Ether was distilled and the resulting aqueous layer was steam distilled. p-Chlorobenzaldehyde, m . p . 47-47.5', was obtained (27.9 g , ) i n 8 3 . 5 ( 2 yield. Recrystallization from hot water did not change the m.p.Reduction with Lithium Tri-n-butoxyaluminohydride on a Preparative Scale .-The use of lithium tri-n-butoxyaluminohyiride is useful in cases where t h e removal of ethyl alcohol from the product offers difficulties.Cyclopropanecarbonitrile. -In a 1-1 ., three-necked, round-bottom flask equipped with a condenser, dropping funnel, and stirrer, flushed with nitrogen, was placed 0.3 mole of lithium aluminum hydride in 300 ml. of ether ( 1 M solution). T o this solution was added dropwise over a period of 75 min., 0.9 mole (66.6 9 . ) of 1butanol, maintaining the temperature a t -10 to -5 " . The reaction was stirred for another 15 min. T o this solution ( -10") was added 20.1 g . (0.3 mole) of cyclopropanecarbonitrile over 15 min., the temperature rising t o 8 " . The reaction was stirred for 1 h r . a t 3" (ice b a t h ) and then decomposed by 300 ml. of 5 AY sulfuric acid. The ether layer was separated and the heterogen-eous aqueous layer was extracted three times with 25-ml. portions of ether. T h e combined ether extracts were washed with sodium bicarbonate solution and water and then dried over sodium sul-

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