Antiferromagnetic half-skyrmions electrically generated and controlled at room temperature.

Topologically protected magnetic textures are promising candidates for information carriers in future memory devices, as they can be efficiently propelled at very high velocities using current-induced spin torques. These textures-nanoscale whirls in the magnetic order-include skyrmions, half-skyrmions (merons) and their antiparticles. Antiferromagnets have been shown to host versions of these textures that have high potential for terahertz dynamics, deflection-free motion and improved size scaling due to the absence of stray field. Here we show that topological spin textures, merons and antimerons, can be generated at room temperature and reversibly moved using electrical pulses in thin-film CuMnAs, a semimetallic antiferromagnet that is a testbed system for spintronic applications. The merons and antimerons are localized on 180° domain walls, and move in the direction of the current pulses. The electrical generation and manipulation of antiferromagnetic merons is a crucial step towards realizing the full potential of antiferromagnetic thin films as active components in high-density, high-speed magnetic memory devices.

Secondary correction of premaxilla in bilateral cleft lip and palate with lag-screw fixation.

It is not unusual for the protruding premaxilla to attain an undesirable position after cleft lip repair. Such a premaxilla may lead to considerable problems in facial aesthetics, or oral functions, or both in early childhood. These abnormal premaxillas may produce difficulties in bone grafting and orthodontic treatment in late childhood. In such cases, surgical correction of the premaxilla in childhood is justified. From 2013 to 2018, 11 children, aged 2 to 11 years, had a secondary ostectomy of their premaxilla. A new stabilisation method (developed by us) was used to provide rigid fixation to the premaxilla. The follow up period ranged from 1 - 6 years. The results were satisfactory in all except for a few minor issues in three patients. There was significant improvement in their appearance, oral functions, and most importantly in their quality of life. The need for secondary osteotomy of the premaxilla should always be weighed against its potential complications. The fixation technique described by us, though, provides rigid fixation, but may potentially be associated with a few complications if not practised carefully.

Imaging Current-Induced Switching of Antiferromagnetic Domains in CuMnAs.

The magnetic order in antiferromagnetic materials is hard to control with external magnetic fields. Using x-ray magnetic linear dichroism microscopy, we show that staggered effective fields generated by electrical current can induce modification of the antiferromagnetic domain structure in microdevices fabricated from a tetragonal CuMnAs thin film. A clear correlation between the average domain orientation and the anisotropy of the electrical resistance is demonstrated, with both showing reproducible switching in response to orthogonally applied current pulses. However, the behavior is inhomogeneous at the submicron level, highlighting the complex nature of the switching process in multidomain antiferromagnetic films.

Electrical switching of an antiferromagnet.

Antiferromagnets are hard to control by external magnetic fields because of the alternating directions of magnetic moments on individual atoms and the resulting zero net magnetization. However, relativistic quantum mechanics allows for generating current-induced internal fields whose sign alternates with the periodicity of the antiferromagnetic lattice. Using these fields, which couple strongly to the antiferromagnetic order, we demonstrate room-temperature electrical switching between stable configurations in antiferromagnetic CuMnAs thin-film devices by applied current with magnitudes of order 10(6) ampere per square centimeter. Electrical writing is combined in our solid-state memory with electrical readout and the stored magnetic state is insensitive to and produces no external magnetic field perturbations, which illustrates the unique merits of antiferromagnets for spintronics.

First Report of Fusarium Wilt in the Broomrape Parasite Growing on Brassica spp. in India.

Broomrape (Orobanche aegyptiaca Pers.), an important obligate root parasitic weed in India, has a wide host range including several members of the Solanaceae, Leguminaceae, and Brassicaceae families, among others. Orobanche plants produce thousands of tiny seeds (250 × 300 µm), which can remain viable in the soil for as long as 13 years (3). Rapeseed-mustard (Brassica spp.) is one of the major oilseed crops in India, cultivated on 5.77 million ha with 6.59 million t produced during 2009-2010. Broomrape has been observed in India as a major angiospermic parasitic plant on rapeseed-mustard, tobacco, tomato, and potato. During a field visit to an experimental farm at the Directorate of Rapeseed-Mustard Research, Bharatpur (27°12'N, 77°27'E) in the winter of 2009-2010, symptoms of wilt disease were observed on Orobanche plants, 32.6% of which had wilted completely following root infection. Initial symptoms appeared as a browning of the flowering stalk with wilting. Direct observation of below ground plant parasite tissues revealed a necrosis starting at the radical and advancing to the collar region that shredded later on. Tissue fragments, excised from the internal portions of the diseased tissue, were surface sterilized with 0.1% HgCl2, plated on 2% potato dextrose agar (PDA) adjusted to pH 7.0, and incubated at 22 ± 2°C for 7 days. The colonies that grew on PDA plates produced a bright purple color. Single-spore culturing of the fungus yielded Fusarium solani on the basis of morphological characteristics (2). The Fungal Identification Service, Mycology and Plant Pathology Group, Agharkar Research Institute, Pune, India (Accession No. 2156) confirmed the identity. The pathogenicity of the fungus was tested by inoculating five healthy Orobanche plants that were parasitizing Brassica spp. at the radicle region with 10-ml spore suspensions (2 × 105 conidia/ml of sterile distilled water) derived from 7-day-old cultures of the fungus. Control plants were treated with sterile distilled water. F. solani-inoculated radicles developed typical wilting symptoms within 2 weeks of treatment, while the control as well as the Brassica spp. plants remained healthy. F. solani was reisolated from inoculated wilted plants, thus fulfilling Koch's postulates. To our knowledge, on the basis of the literature, this is the first report from India showing that F. solani infects O. aegyptica on Brassica spp. There are reports of fungi (50 different species) infecting different hosts in Southern Italy, including F. oxysporum and F. solani, which have been found to be pathogenic to O. ramose. The most pathogenic Fusarium isolates significantly increased the number of dead spikes of broomrape (1). Control of Orobanche spp. poses a challenge because of the lack of effective and economic control measures. F. solani thus offers a potentially promising management strategy that should be explored in the future for the control of O. aegyptiaca. References: (1) A. Boari et al. Biol. Control 30:212, 2004. (2) P. E. Nelson et al. Fusarium Species: An Illustrated Manual for Identification. 1st ed. Pennsylvania State University Press, University Park, 1983. (3) M.C. Press et al. Parasitic Plants. Chapman and Hall, London, UK, 1995.

A New Flavanonol Glycoside from Adansonia digitata Roots.

A new flavanonol glycoside isolated from the roots of Adansonia digitata has been characterised as 3,7-dihydroxy flavan-4-one-5-O-beta- D-galactopyranosyl (1 --> 4)-beta- D-glucopyranoside on the basis of degradation, spectral and chemical studies.