First Evidence of Axial Shape Asymmetry and Configuration Coexistence in ^{74}Zn: Suggestion for a Northern Extension of the N=40 Island of Inversion

The excited states of N=44 ^{74}Zn were investigated via γ-ray spectroscopy following ^{74}Cu β decay. By exploiting γ-γ angular correlation analysis, the 2_{2}^{+}, 3_{1}^{+}, 0_{2}^{+}, and 2_{3}^{+} states in ^{74}Zn were firmly established. The γ-ray branching and E2/M1 mixing ratios for transitions deexciting the 2_{2}^{+}, 3_{1}^{+}, and 2_{3}^{+} states were measured, allowing for the extraction of relative B(E2) values. In particular, the 2_{3}^{+}→0_{2}^{+} and 2_{3}^{+}→4_{1}^{+} transitions were observed for the first time. The results show excellent agreement with new microscopic large-scale shell-model calculations, and are discussed in terms of underlying shapes, as well as the role of neutron excitations across the N=40 gap. Enhanced axial shape asymmetry (triaxiality) is suggested to characterize ^{74}Zn in its ground state. Furthermore, an excited K=0 band with a significantly larger softness in its shape is identified. A shore of the N=40 "island of inversion" appears to manifest above Z=26, previously thought as its northern limit in the chart of the nuclides.

First Direct Measurement of an Astrophysical p-Process Reaction Cross Section Using a Radioactive Ion Beam

We have performed the first direct measurement of the ^{83}Rb(p,γ) radiative capture reaction cross section in inverse kinematics using a radioactive beam of ^{83}Rb at incident energies of 2.4 and 2.7A  MeV. The measured cross section at an effective relative kinetic energy of E_{cm}=2.393  MeV, which lies within the relevant energy window for core collapse supernovae, is smaller than the prediction of statistical model calculations. This leads to the abundance of ^{84}Sr produced in the astrophysical p process being higher than previously calculated. Moreover, the discrepancy of the present data with theoretical predictions indicates that further experimental investigation of p-process reactions involving unstable projectiles is clearly warranted.

Absence of Low-Energy Shape Coexistence in ^{80}Ge: The Nonobservation of a Proposed Excited 0_{2}^{+} Level at 639 keV

The ^{80}Ge structure was investigated in a high-statistics β-decay experiment of ^{80}Ga using the GRIFFIN spectrometer at TRIUMF-ISAC through γ, β-e, e-γ, and γ-γ spectroscopy. No evidence was found for the recently reported 0_{2}^{+} 639-keV level suggested as evidence for low-energy shape coexistence in ^{80}Ge. Large-scale shell model calculations performed in ^{78,80,82}Ge place the 0_{2}^{+} level in ^{80}Ge at 2 MeV. The new experimental evidence combined with shell model predictions indicate that low-energy shape coexistence is not present in ^{80}Ge.

Erratum: Direct Observation of Proton Emission in ^{11}Be [Phys. Rev. Lett. 123, 082501 (2019)]

This corrects the article DOI: 10.1103/PhysRevLett.123.082501.

Direct Observation of Proton Emission in ^{11}Be

The elusive β^{-}p^{+} decay was observed in ^{11}Be by directly measuring the emitted protons and their energy distribution for the first time with the prototype Active Target Time Projection Chamber in an experiment performed at ISAC-TRIUMF. The measured β^{-}p^{+} branching ratio is orders of magnitude larger than any previous theoretical model predicted. This can be explained by the presence of a narrow resonance in ^{11}B above the proton separation energy.

Action of testosterone in melanin metabolism in liver of toad (Bufo melanostictus)

The melanin content of liver of male toad was altered by testosterone injection. A single injection of testosterone at a dose of 1 microgram/g or 2 microgram/g of body weight caused an increase in melanin content of liver of male toad on the 3rd and 5th day after injection. With lower doses (0.1 microgram/g and 0.5 microgram/g), however, there was no alteration of melanin content of liver. Compared to the results obtained with 1 microgram of testosterone per g of body weight, the degree of response with respect to the melanin content with 2 microgram/g tended to be higher, but the difference was not statistically significant. The female toads remained unaffected with respect to melanin content of liver with these doses of testosterone used.

Histochemical studies on the effect of thyroid hormone on alkaline and acid phosphatase activities in liver of fish and amphibia

The Lata fishes (Ophicephalus punctatus) showed increased alkaline and acid phosphatase activities in liver after immersion for 15-30 days in thyroxine-containing medium (0.025 mug/ml). A single injection of thyroxine (1-2 mug/g of body weight) caused increased acid phosphatase activity in liver of Lata fish in comparison to the controls on the 5th day after experiment but the alkaline phosphatase activity remained unchanged. Both alkaline and acid phosphatases showed increased activities in liver of Lata fishes treated with a single injection of 4 mug of thyroxine per g of body weight on the 5th day. Immersion of Lata fishes in thiourea solution (1 mg/ml) for 15 days did not show any alteration in alkaline or acid phosphatase activities but these enzyme activities decreased after 30 days' immersion in thiourea solution in comparison to the controls. A seasonal variation of alkaline and acid phosphatase activities was observed in liver of Lata fishes. More alkaline phosphatase activity was found in liver of summer fishes than in winter fishes. The winter fishes showed more acid phosphatase activity than the summer fishes. Three consecutive injections of thyroxine (0.1 mug/g of body weight) to toads (Bufo melanostictus) caused increased alkaline and acid phosphatase activities in liver on the 5th day of the experiment, in comparison to the controls.

The 13C Fourier Transform Spectrum of Heparin. Evidence for a Biose Repeating Sequence of Residues

Carbon-13 Fourier transform n.m.r. spectra of the biopolymer, heparin, are described. The proton-decoupled spectrum corresponds to that of a molecular structure based on 12 carbon atoms, and the observed chemical shifts are shown to be consistent with a previously-proposed alternating sequence consisting of (1 → 4) linked residues of α-D-idopyranosyluronic acid 2-sulfate and 2-deoxy-2-sulfamino-α-D-glucopyranosyl 6-sulfate. Line-broadening of the C-6 signal of the latter residue indicates that spin–spin relaxation of the 13C nucleus of this sulfated primary carbinol group is more effective than for the 13C nuclei of the sugar rings. Among model compounds utilized for assignment of the signals from heparin is a disaccharide, 4-O-(α-L-idopyranosyluronic acid 2-sulfate)-2,5-anhydro-D-mannose 6-sulfate, prepared in 65% yield by deaminative degradation of heparin.

Identification of di-O-, tri-O-, and tetra-O-methylmannoses by gas–liquid chromatography

not available

Structures of yeast mnnans containing both α- and β-linked D-mannopyranose units

Several mannans from yeasts give proton magnetic resonance spectra with distinctive H-1 signals at higher field than τ 4.55. A number of these mannans were investigated polarimetrically and each has a specific rotation corresponding to a mixture of α- and β-D-linkages. Four were partially hydrolyzed and shown to have most of the α-linkages in the main chains and the β-linkages in the side chains. Detailed structural investigations showed that the Pichiapastoris mannan probably has an α-(1→6)-D-manno-pyranosyl main-chain substituted in the 2-positions with a substantial proportion of O-α-D-mannopy-ranosyl-(1→2)-O-β-D-mannopyranosyl-(1→2)-O-β-D-mannopyranosyl-(1→2)-O-α-mannopyranosyl side-chains (1). The related mannan from Citeromycesmatritensis has a similar main-chain, which is substituted in the 2-positions by α-D-mannopyranosyl units and β-(1→2)-pyranose-linked D-mannotriosyl and perhaps mannobiosyl side-chains (2).

Identification of di-O-, tri-O-, and tetra-O-methylmannoses by gas–liquid chromatography

Some di-O- and tri-O-methylmannoses which are unknown or difficult to prepare have been synthesized. These and the other isomers, which can arise from methylation–fragmentation analyses of mannofuranose- and mannopyranose-containing polysaccharides can be used as gas–liquid chromatographic (g.l.c.) standards. A system has been devised in which methylation fragments are fractionated on a cellulose column into di-O-, tri-O-, and tetra-O-methylmannose fractions, which are then analyzed individually by g.l.c. following conversion to suitable derivatives.

Hydrogenolysis of carbohydrate acetals, ketals, and cyclic orthoesters with lithium aluminium hydride – aluminium trichloride

The reduction of hexofuranose and hexopyranose acetals with LiAlH4–AlCl3 (1:1, probably AlH2Cl) to the corresponding ethers proceeds in similar fashion as that of simple acetals and ketals (Scheme I) (refs. 1–7). Certain O-methyl and O-benzyl derivatives, not readily obtainable otherwise, are conveniently synthesized from appropriate acetals in this way. Cyclic orthoesters of glucofuranose may be selectively reduced to acetals; the steric course of such reduction has been shown unequivocally in the case of orthoformates (Scheme II). Of several cleavable groups, the ease of hydrogenolysis is (a) cyclic orthoester > isopropylidene ketal, cyclohexylidene ketal > benzylidene acetal > ethylidene acetal > formal and (b) 5,6-O-linked or 3,5-O-linked acetal or ketal > 1,2-O-linked acetal or ketal.

A STUDY OF THE PECTIN PRESENT IN THE BARK OF AMABILIS FIR (ABIES AMABILIS)

A pectic material has been isolated from the bark of Abies amabilis (Dougl.) Forbes in a yield of 2%. On hydrolysis it yielded D-galacturonic acid, D-galactose, and L-arabinose in a ratio of 85:4:11, and also traces of rhamnose. The product, when submitted to several conventional fractionation methods, appeared homogeneous. Further resolution could be effected by acidification of an aqueous solution of the pectin, followed by ultracentrifugation. The insoluble portion (50%) was an electrophoretically homogeneous galacturonan with [α]D + 246°. The material remaining in solution (30%), here referred to as a pectic acid, had [α]D + 225° and on hydrolysis gave D-galacturonic acid, D-galactose, and L-arbabinose in a ratio of 74:7:19, as well as traces of rhamnose.The structure of the galacturonan was established by partial hydrolysis and methylation. It consisted of α-D-galacturonic acid residues linked together by (1 → 4)-glycosidic bonds to a linear macromolecule. The same techniques were applied to the pectic acid. While a unique structural formula could not be assigned in this case, one probable alternative involved a framework of (1 → 4)-linked α-D-galacturonic acid residues together with a few residues of 1,2,4-linked L-rhamnose. Some of the galacturonic acid units carried at C-2 and C-3 side chains which were terminated by D-galactopyranose and L-arabinofuranose residues. A few of the latter also occurred as inner units, probably in the side chains. This appears to be the first time a pectic material has been resolved into a galacturonan and a pectic acid containing the four sugar residues usually found in pectins. It is probable that the pectin occurring to a limited extent in wood has a similar composition.