The 2021 Magnonics Roadmap

Magnonics is a budding research field in nanomagnetism and nanoscience that addresses the use of spin waves (magnons) to transmit, store, and process information. The rapid advancements of this field during last one decade in terms of upsurge in research papers, review articles, citations, proposals of devices as well as introduction of new sub-topics prompted us to present the first roadmap on magnonics. This is a collection of 22 sections written by leading experts in this field who review and discuss the current status besides presenting their vision of future perspectives. Today, the principal challenges in applied magnonics are the excitation of sub-100 nm wavelength magnons, their manipulation on the nanoscale and the creation of sub-micrometre devices using low-Gilbert damping magnetic materials and its interconnections to standard electronics. To this end, magnonics offers lower energy consumption, easier integrability and compatibility with CMOS structure, reprogrammability, shorter wavelength, smaller device features, anisotropic properties, negative group velocity, non-reciprocity and efficient tunability by various external stimuli to name a few. Hence, despite being a young research field, magnonics has come a long way since its early inception. This roadmap asserts a milestone for future emerging research directions in magnonics, and hopefully, it will inspire a series of exciting new articles on the same topic in the coming years.

Magnon Straintronics: Reconfigurable Spin-Wave Routing in Strain-Controlled Bilateral Magnetic Stripes

We observe and explain theoretically strain-induced spin-wave routing in the bilateral composite multilayer. By means of Brillouin light scattering and microwave spectroscopy, we study the spin-wave transport across three adjacent magnonic stripes, which are strain coupled to a piezoelectric layer. The strain may effectively induce voltage-controlled dipolar spin-wave interactions. We experimentally demonstrate the basic features of the voltage-controlled spin-wave switching. We show that the spin-wave characteristics can be tuned with an electrical field due to piezoelectricity and magnetostriction of the piezolayer and layered composite and mechanical coupling between them. Our experimental observations agree with numerical calculations.

[The structure of antibiotic eremomycin B]

A new biologically active component, antibiotic eremomycin B, was isolated from the culture liquid of Amycolatopsis orientalis subsp. eremomycini, the producing strain for antibiotic eremomycin. Its structure was established by NMR spectroscopy and mass spectrometry. Eremomycin B was shown to differ from eremomycin by the presence of an N-carboxymethyl substituent in the disaccharide eremosamine fragment.

Production of antifungal cellobiose lipids by Trichosporon porosum

The yeast Trichosporon porosum suppresses growth of ascomycetes and basidiomycetes belonging to 52 genera. It is due to secretion of a thermostable fungicidal agent. The suppression was maximal at pH 3.5-4.0. Fungicidal preparation obtained from the culture broth was shown to be a mixture of cellobiosides of dihydrodecane acid with different degree of acetylation of cellobiose residue. The preparation caused the death of Candida albicans and Filobasidiella neoformans cells in the concentrations of 0.2 and 0.03 mM, respectively.

[Polysaccharides of algae: 60. Fucoidan from the Pacific brown alga Analipus japonicus (Harv.) Winne (Ectocarpales, Scytosiphonaceae)]

A fucoidan containing L-fucose, sulfate, and O-acetyl groups at a molar ratio of 3 : 2 : 1, as well as minor amounts of xylose, galactose, and uronic acids was isolated from the brown alga Analipus japonicus collected in the Sea of Japan. The structures of the native polysaccharide and the products of its desulfation and deacetylation were studied by the methods of methylation, periodate oxidation, and NMR spectroscopy. It was shown that the polysaccharide molecule mainly consists of a linear carbohydrate chain of (1-->3)-linked alpha-L-fucopyranose residues, which bear numerous branches in the form of single alpha-L-fucopyranose residues (three branches at position 4 and one branch at position 2 per each ten residues of the main chain). Sulfate groups occupy positions 2 and (to a lesser extent) 4, most of the terminal nonreducing fucose residues being sulfated twice. The acetyl groups are located predominantly at positions 4. The structural role of minor monosaccharides was not established.

[Computation techniques in the conformational analysis of carbohydrates]

A growing number of modern studies of carbohydrates is devoted to spatial mechanisms of their participation in the cell recognition processes and directed design of inhibitors of these processes. Any progress in this field is impossible without the development of theoretical conformational analysis of carbohydrates. In this review, we generalize literature data on the potentialities of using of different molecular-mechanic force fields, the methods of quantum mechanics, and molecular dynamics to study the conformation of glycoside bond. A possibility of analyzing the reactivity of carbohydrates with the computation techniques is also discussed in brief.

[Fungicidal activity of cellobiose lipids from cultural fluid of yeast Cryptococcus humicola and Pseudozyma fusiformata]

Cellobiose lipids of yeast fungi Cryptococcus humicola and Pseudozyma fusiformata have similar fungicidal activities against different yeast, including pathogenic Cryptococcus and Candida species. Basidiomycetic yeast reveals maximum sensitivity to these preparations; e.g., cells of cryptococcus Filobasidiella neoformans almost completely die after 30-min incubation in a glycolipid solution at a concentration of 0.02 mg/ml. The same effect toward ascomycetous yeast, including pathogenic Candida species, is achieved only at five to eight times higher concentrations of glycolipids. The cellobiose lipid from P. fusiformata, which, unlike glycolipid from Cr. humicola, has hydroxycaproic acid residue as O-subtituent of cellobiose and additional 15-hydroxy group in aglycone, inhibits the growth of the studied mycelial fungi more efficiently than the cellobiose lipid from Cr. humicola.

Effect of enzyme preparation from the marine mollusk Littorina kurila on fucoidan from the brown alga Fucus distichus

A fucoidanase preparation from the marine mollusk Littorina kurila cleaved some glycosidic bonds in fucoidan from the brown alga Fucus distichus, but neither fucose nor lower oligosaccharides were produced. The main product isolated from the incubation mixture was a polysaccharide built up of disaccharide repeating units -->3)-alpha-L-Fucp-(2,4-di-SO3(-))-(1-->4)-alpha-L-Fucp-(2SO3(-))-(1-->, the structure coinciding with the idealized formula proposed for the initial substance. A polymer fraction with the same carbohydrate chain but sulfated only at positions 2 and nonstoichiometrically acetylated at positions 3 and 4 of fucose residues was isolated as a minor component. It is suggested that the native polysaccharide should contain small amounts of non-sulfated and non-acetylated fucose residues, and only their glycosidic bonds are cleaved by the enzyme. The enzymatic hydrolysis showed that irregular regions of the native polysaccharide containing acetylated and partially sulfated repeating units were assembled in blocks.

The Synthesis and NMR and Conformational Studies of Fucoidan Fragments: VI.1Fragments with an -(1 2)-Linked Fucobioside Unit

A series of selectively sulfated di- and trisaccharide derivatives corresponding to the potential fragments of fucoidans with a (1-->2)-alpha-bound fucobioside unit were synthesized and studied by 1H and 13C NMR spectroscopy. NOE experiments and molecular modeling were used for a conformational analysis of the compounds synthesized. In the case of disaccharides, the experimental NOE values were found to agree with those obtained using modeling with the use of density functional theory (DFT) and differ from those resulting from modeling by the molecular mechanics MM3 force field. Trisaccharide fragments partially or completely sulfated in position 4 turned out to be correctly described by both MM3 force field and DFT computation. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 2; see also http://www.maik.ru.

Structure and serological specificity of a new acidic O-specific polysaccharide of Proteus vulgaris O45

The following structure of the O-specific polysaccharide (OPS) of Proteus vulgaris O45 lipopolysaccharide (LPS) was established using 1H- and 13C-NMR spectroscopy, including two-dimensional NOESY and H-detected 1H, 13C heteronuclear multiple-quantum coherence ( HMQC) experiments: [structure: see text text] Immunochemical studies, using rabbit polyclonal anti-P. vulgaris O45 serum and LPS, OPS and Smith-degraded OPS of P. vulgaris O45, showed the importance of beta-D-GlcA in manifesting the serological specificity of the O-antigen studied.

Structural and serological studies on a new acidic O-specific polysaccharide of Proteus vulgaris O32

The following structure of the O-specific polysaccharide chain (O-antigen) of the Proteus vulgaris 032 lipopolysaccharide (LPS) was established by 1H-NMR and 13C-NMR spectroscopy, including two-dimensional NOESY and H-detected 1H,13C heteronuclear multiple-quantum coherence (HMQC) experiments: -->2)-alpha-L-RhapI-(1-->2)-alpha-L-RhapII-(1-->4)-beta-D-++ +GalpA(I)-(1-->3)-beta-D-GlcpNAc-(1-->4)-alpha-D-GalpA(II)-(1-- >. In addition, an O-acetyl group was detected, which, most probably, is located at position 3 of a part of RhapI residues. Serological studies, using rabbit polyclonal anti-(P. vulgaris 032) serum, homologous and heterologous Proteus O-antigens and related artificial antigens, revealed the importance of an a-D-GalA-associated epitope in manifesting the immunospecificity of P. vulgaris 032 and substantiated serological relationships between the O-antigen studied and those of some other Proteus strains.

Structure of teichoic acid of the cell wall of Streptomyces sparsogenes VKM Ac-1744T

The cell wall of Streptomyces sparsogenes VKM Ac-1744T contains a teichoic acid of 1,3-poly(glycerol phosphate) type. The polymer is composed of about 11 repeating units of the following structure: The structure was not identified in gram-positive bacteria previously. The data are in agreement with DNA-relatedness between Streptomyces sparsogenes and Streptomyces hygroscopicus species and suggest the species-specificity of teichoic acid structure in the studied streptomycetes group.