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Abstract: A novel piezoelectric (PZ) immunosensor for the direct detection of malarial Plasmodium falciparum histidine rich protein-2 (PfHRP-2) antigen was developed. The mixed self-assembled monolayers (SAMs) of thioctic acid and 1-dodecanethiol were formed on gold surface of quartz crystal. Cyclic voltammetry, electrochemical impedance spectroscopy and surface Raman spectroscopy techniques were used to characterize the mixed SAMs. The rabbit anti-PfHRP-2 antibodies were coupled on mixed SAM modified gold surface of quartz crystal via NHS/EDC activation method. The PZ immunosensor was applied to detect PfHRP-2 in the linear range of 15–60ng/ml with a detection limit of 12ng/ml. It was also found that even after 14 days of storage, 50% of the activity still remained. Clinical human serum samples were tested with this method, and the results were in agreement with those obtained from commercially available ICT kit (NOW® Malaria). [Copyright &y& Elsevier]

The orthorhombic Haldane-spin chain compound Tb 2 BaNiO 5 (Néel order, T N1 = 63 K) has been shown to be an exotic multiferroic system below (T N2 =) 25 K due to various fascinating features, pointing to a strong potential for the advancement of concepts in this field. In particular, the rare-earth ions play a direct decisive role unlike in many other well-known multiferroic materials and there appears to be a critical canting angle, developing below T N 2, subtended by Tb 4 f and Ni 3d moments to trigger this cross-coupling phenomenon. However, for a small replacement of Sr for Ba, viz. in Tb 2 Ba 0.9 Sr 0.1 NiO 5 , ferroelectricity was reported to get destroyed, but retaining magnetic features at (T N1 =) 55 K and (T N2 =) 14 K. In this article, we address the origin of suppression of multiferrocity in this Sr-doped system through neutron diffraction studies and density functional theory calculations. We find that, unlike in Tb 2 BaNiO 5 , there is no pronounced change in the relative canting angle of the magnetic moments around T N2 and that the absolute value of this parameter down to 2 K fails to exceed the critical value noted for the parent, thereby explaining the origin of destruction of magnetoelectric coupling in the Sr-doped material. This finding renders strong support to the proposal of possible existence of 'critical canting angle' – at least in some cases – to induce multiferroicity, apart from serving as a route to engineer multiferroic materials for applications. • Tb 2 BaNiO 5 has been known to be an exotic multiferroic compound. • A small doping of Sr for Ba was reported to suppress multiferroicity. • Here the results of neutron diffraction and DFT theory are reported. • Canting angles Tb4f and Ni3d moments are reduced due to Sr-doping. • This work supports the idea of critical canting angle for multiferroicity. [ABSTRACT FROM AUTHOR]

Here, europium-doped (1 to 11 mol%) and titanium (1 to 5 mol%)co-doped SrY 2 O 4 :Eu phosphors were synthesized using solid-state reaction method. The synthesized samples were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and photoluminescence (PL) techniques for structural, morphological, functional group, and photoluminescence studies, respectively. XRD patterns confirmed the formation of pure phase SrY 2 O 4 at 1300°C and structural parameters were further determined using Rietveld refinement. FESEM micrographs revealed that doped and co-doped samples had different morphological features. All the samples were excited at ultraviolet light excitation and emission spectra consisted of peaks corresponding to the Eu ions. The maximum PL intensity was observed for 9 mol% of Eu ions and 3 mol% co-doping of Ti ions. The synthesized phosphors have potential applications in optoelectronics and display devices., (© 2022 John Wiley & Sons Ltd.)

This study brings out the critical role of lesser-known local plant species in the food, nutrition and livelihood security of Adi community in Arunachal Pradesh, India. Considering women as a major custodian in knowledge and practices on foods, a total of 90 Adi women and 60 key knowledgeable community members (thus a total of 150 participants) were selected from East Siang and Upper Siang districts of Arunachal Pradesh. Data were collected using combination of methods including recipe contest, focus group discussion, personal interviews and laboratory analyses. The results indicated that Adi women were able to identify 39 bioculturally important species from a range of locally available plant species. Used alone or with other foods, these plants remain central to the Adi people's cultural identity and livelihood security. In addition to improving food and nutritional security, these species accessed from different land use systems, are also sold on the local markets to generate decent incomes. Of the species identified by Adi women, 28 were culturally shared and used frequently in food and ethnomedicine. Laboratory analyses of the selected 22 species revealed exceptionally high levels of minerals and other nutrients, such as proteins and anti-oxidants, supporting their traditional use for health benefits. Our study results provide valuable insights to the researchers to explore the vast hidden potential of these and other similar species for improving nutritional well-being of local communities in marginal areas. Adequate policy support is needed to enable Adi and other such marginalized communities to cope with challenges being posed to traditional food systems., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Singh, Bhardwaj, Singh, Payum, Rai, Singh, Wangchu and Upadhyay.)

The Haldane spin-chain compound, Tb 2 BaNiO 5 , with two antiferromagnetic transitions, one at T 1   =  63 K and the other at T 2   =  25 K, has been recently shown to be an exotic multiferroic below T 2 . Here, we report the results of our investigation of Sr doping at the Ba site by magnetization, heat-capacity, magnetodielectric (MDE) and pyrocurrent measurements. An intriguing finding, which we stress, is that the ferroelectricity is lost even for a doping level of ten atomic percent, though magnetic ordering prevails. The doped specimens however retain significant MDE behaviour, but with reduced magnitudes and qualitative changes with respect to the behaviour of the parent compound. This implies that ferroelectric order is also crucial for the anomalously large MDE in the parent compound, in addition to the role of 4f single-ion anisotropy.

The present work reports magnetic, magnetoelastic and magnetoelectric (ME) response of scandium (Sc) doped barium hexaferrite, BaFe 10 Sc 2 O 19 . DC magnetization shows that partial substitution of non-magnetic Sc for Fe in barium hexaferrite results in a reduction of Curie temperature (T C ) from 730 K known for the parent compound BaFe 12 O 19 to 430 K. Magnetization measurements show that, in BaFe 10 Sc 2 O 19 , in addition to the magnetic transition at 250 K corresponding to longitudinal conical magnetic structure, another magnetic anomaly occurs in the vicinity of 50 K (T max ). Ac susceptibility and magnetic relaxation show that the magnetic transition at T max is associated with spin glass like dynamics. Field dependence of this glassy transition temperature follows the Almeida-Thouless (A-T) line expected for spin glass-like behaviour. Unit cell volume obtained from the neutron diffraction (ND) measurements shows deviation from the Debye-Gruneisen behaviour below 50 K, revealing the magnetoelastic coupling. Existence of magnetoelastic coupling is also confirmed by Raman spectra as Raman modes show anomalous changes around 50 K and also indicates presence of lattice modulation. Further, the magnetic structure obtained from ND data shows that incommensurate longitudinal conical ferrimagnetic structure persists from 210 K to 3 K. The integrated intensity of (0 0 2) peak and magnetic moments undergoes a subtle change below 50 K that seems to favour coexistence of long range magnetic ordering and spin glass-like dynamics. Significant magneto-dielectric effect was observed around 50 K. Temperature dependent studies of dielectric constant and pyroelectric current indicate the presence of ferroelectricity even in zero magnetic field. Further, existence of ME coupling below 50 K is confirmed by temperature dependence of pyroelectric current under magnetic fields up to 70 kOe. In short, this work identifies a new magnetic anomaly around 50 K, which is spin-glass-like inducing magnetoelastic and ME anomalies, even in the absence of external magnetic fields.

We report the magnetic behavior of two intermetallic-based kagome lattices, Tb 3 Ru 4 Al 12 and Er 3 Ru 4 Al 12 , crystallizing in the Gd 3 Ru 4 Al 2 -type hexagonal crystal structure, by measurements in the range 1.8-300 K with bulk experimental techniques (ac and dc magnetization, heat capacity, and magnetoresistance). The main finding is that the Tb compound, known to order antiferromagnetically below (T N =) 22 K, shows glassy characteristics at lower temperatures ([Formula: see text]15 K), thus characterizing this compound as a re-entrant spin-glass. The data reveal that the glassy phase is quite complex and is of a cluster type. Since glassy behavior was not seen for the Gd analog in the past literature, this finding on the Tb compound emphasizes that this kagome family could provide an opportunity to explore the role of higher-order interactions (such as quadrupole) in bringing out magnetic frustration. Additional findings reported here for this compound are: (i) The plots of temperature dependence of magnetic susceptibility and electrical resistivity data in the range 12-20 K, just below T N , are found to be hysteretic leading to a magnetic phase in this intermediate temperature range, mimicking disorder-broadened first-order magnetic phase transitions; (ii) features attributable to an interesting magnetic phase co-existence phenomenon in the isothermal magnetoresistance in zero field, after travelling across metamagnetic transition fields, are observed. With respect to the Er compound, we do not find any evidence for long-range magnetic ordering down to 2 K, but this compound appears to be on the verge of magnetic order at 2 K.

Keeping current interests to identify materials with intrinsic magnetodielectric behaviour near room temperature and with novel pyroelectric current anomalies, we report temperature and magnetic-field dependent behavior of complex dielectric permittivity and pyroelectric current for an oxide, Li 2 Ni 2 Mo 3 O 12 , containing magnetic ions with (distorted) honey-comb and chain arrangement and ordering magnetically below 8 K. The dielectric data reveal the existence of relaxor ferroelectricity behaviour in the range 160-240 K and there are corresponding Raman mode anomalies as well in this temperature range. Pyrocurrent behavior is also consistent with this interpretation, with the pyrocurrent peak-temperature interestingly correlating with the poling temperature. 7 Li NMR offer an evidence for crystallographic disorder intrinsic to this compound and we therefore conclude that such a disorder is apparently responsible for the randomness of local electric field leading to relaxor ferroelectric property. Another observation of emphasis is that there is a notable decrease in the dielectric constant with the application of magnetic field to the tune of about -2.4% at 300 K, with the magnitude varying marginally with temperature. Small loss factor values validate the intrinsic behaviour of the magnetodielectric effect at room temperature.

The membrane disruption and pore-forming mechanism of melittin has been widely explored by experiments and computational studies. However, the precise mechanism is still enigmatic, and further study is required to turn antimicrobial peptides into future promising drugs against microbes. In this study, unbiased microsecond (µs) time scale (total 17 µs) atomistic molecular dynamics simulation were performed on multiple melittin systems in 1,2-dimyristoyl-sn-glycero-3-phosphocholine membrane to capture the various events during the membrane disorder produced by melittin. We observed bent U-shaped conformations of melittin, penetrated deeply into the membrane in all simulations, and a special double U-shaped structure. However, no peptide transmembrane insertion, nor pore formation was seen, indicating that these processes occur on much longer timescales, and suggesting that many prior computational studies of melittin were not sufficiently unbiased.

In this paper an attempt was made to detect Staphylococcal enterotoxin B (SEB) both by electrochemical and fluorescence immunoassay methods using zinc sulphide (ZnS) QDs. Wet-chemical method was adopted for the preparation of fluorescent ZnS QDs (diameter ∼ 5-10 nm). These QDs were bioconjugated with monoclonal antibodies and then characterized by various method. A detection limit of 0.02 ng mL -1 by fluorescence assay and 1.0 ng mL -1 by electrochemical assay for SEB was achieved. While by sandwich ELISA it is possible to detect 0.24 ng mL -1 only. The sensitivity of all techniques is very good, since the LD 50 of SEB is 20 ng kg -1 . Electrochemical assay is faster, need low-cost instrument, independent to the size of QDs and found to be one of the best alternative methods as compared to the other existing methods studied herein. The presented method could be expanded to the development of electrochemical and fluorescence biosensors for various agents for field and laboratory use.