Magnetic Tunability of Permalloy Artificial Spin Ice Structures

This paper reports tunable Ni80Fe20 artificial spin ice structures of various geometrical lattice arrangements as a function of film thickness. We achieve the magnetic tunability by three distinct methods namely, geometrical arrangements of nanomagnetic elements in the form of square, kagome, and triangular lattices with the variation in film thickness (20, 30, and 50 nm) for each geometry and the applied field orientations. Magnetic force microscopy reveals that the nanoelements are in single-domain states, obeying the spin ice rules for the 20-nm-thick spin ice structures. A combination of nanoelements in single-domain and vortex states is observed with the increase in thickness up to 30 nm. For the 50-nm-thick elements, vortex and flux closure states are in evidence. Broadband ferromagnetic resonance spectroscopy establishes the presence of distinct resonant modes that are spatially localized in the nanomagnets of different orientations and, hence, can be controlled by the applied field orientations. The role of shape anisotropy on the static and dynamic properties is investigated systematically and complemented by extensive micromagnetic simulations. The results show great potential towards designing reconfigurable magnonic crystals for microwave filter applications

Engineering spin wave spectra in thick Ni80Fe20 rings by using competition between exchange and dipolar fields

Control of the spin wave dynamics in nanomagnetic elements is very important for the realization of a broad range of novel magnonic devices. Here we study experimentally the spin wave resonance in thick ferromagnetic rings (100 nm) using perpendicular ferromagnetic resonance spectroscopy. Different from what was observed for the continuous film of the same thickness, or from rings with similar lateral dimensions but with lower thicknesses, the spectra of thick patterned rings show a nonmonotonic dependence of the mode intensity on the resonance field for a fixed frequency. To explain this effect, the theoretical approach by considering the dependence of the mode profiles on both the radial and axial coordinates was developed. It was demonstrated that such unusual behavior is a result of the competition between exchange and dipolar fields acting at the spin excitations in the structure under study. The calculations are in a good agreement with the experimental results

Effects of Workplace Ethics on Employees and Organisational Productivity in Nigeria

Man's abysmal failure to uphold ethical behaviour within the framework of employment relationship, necessitates continuous interrogation of the complex issues, which arise from the asymmetry between productivity and employees' commitment. This paper examines the effects of etiquette and unethical behaviour on employee commitment and productivity in Nigeria. A descriptive survey research method was adopted for the study using one hundred and eleven valid questionnaires, which were administered on Employees in Government Establishments, Organised Private Sector, Indigenous, Asian and Lebanese Companies operating in Ikeja, Oshodi, Ikorodu, Isolo and lganmu Industrial Estates of Lagos State, Nigeria. Secondary data as well as documented evidence were also reviewed and used for the study. The sampling procedure was carried out randomly. The data collected were analyzed through Structural Equation Modelling and supported by descriptive statistics. Each item was based on a 5-Point-Likert scale. AMOS 22 was adopted in testing the study hypotheses; the data was presented with the use of SPSS while Structural Equation Modeling (SEM) was utilized due to its generality and flexibility to evaluate the validity of regression and correlation between the observed variables. The results show that significant relationship exists between ethical standards and organisational productivity, in Nigeria and that integrity cum discipline have negative impact on improved productivity level of the organization, which could be attributed to the nature of these virtues being abstract and could only be seen or observed overtime. The study suggests that all government agencies such as National Pension Commission (PENCOM), Nigerian Investment Promotion Commission (NIPC), Economic & Financial Crimes Commission & Independent Corrupt Practices, etc. saddled with the duty of ensuring etiquette in workplaces, should discharge their responsibilities more diligently and sanction organisations found guilty of unethical conducts in business concern and employment relationships

Shelf Life Study and Quality Attributes of Cocoyam Chips

The study was carried out to determine changes in the quality indices (levels of peroxides values, acid values, pH and colour) of cocoyam chips and microbiological safety (bacterial, yeast and mould counts) of cocoyam chips as influenced by temperature during storage period of fried cocoyam chips. Cocoyam tubers were processed into chips of 3mm thickness; the slices were then fried at a frying temperature of 170°C in a shallow pot for 7 minutes and was packaged in polyethylene bags and stored under room and refrigerator temperature. The results showed that there was significant difference (p≤0.05) between quality indices, microbiological safety and storage temperature and packaging materials. From week 0-5, peroxide values of samples stored under refrigeration temperature were found to be low, ranged from 3.39 - 11.58 meq kg-1, while the samples stored in the room temperature were found to be higher 3.81 - 12.87 meq kg-1. Acid values were also found to be low in the samples stored in the refrigerator, ranged from 5.79 - 16 3.34mg/g and the samples that were stored in the room temperature ranged from 9.94 - 24.05mg/g. The samples stored under refrigeration temperature had low bacterial counts ranged from 5.0 x 101 - 6.2 x 101 cfu/ml while samples stored in the room temperature had higher bacterial counts, ranged from 9.0 x 101 – 74 x 101 cfu/ml. Yeast and mould counts in samples stored under refrigeration temperature ranged from 4.0 x 101 - 32 x 10 cfu/ml while the samples that were stored in room temperature had higher counts, ranged from 3.0 x 10 – 38 x 10 cfu/ml. pH ranged between 6.88 - 7.02 for both samples during storage period. The results showed that storage temperature and properly sealed packaging material has effect on the above parameters that were determined. There were also colour changes during the storage period

An observation of spin-valve effects in a semiconductor field effect transistor: a novel spintronic device

We present the first spintronic semiconductor field effect transistor. The injector and collector contacts of this device were made from magnetic permalloy thin films with different coercive fields so that they could be magnetized either parallel or antiparallel to each other in different applied magnetic fields. The conducting medium was a two dimensional electron gas (2DEG) formed in an AlSb/InAs quantum well. Data from this device suggest that its resistance is controlled by two different types of spin-valve effect: the first occurring at the ferromagnet-2DEG interfaces; and the second occuring in direct propagation between contacts.Comment: 4 pages, 2 figure

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Fungal mycotoxins in foods: A review

This study aimed to review fungal mycotoxins in foods, their roles and significance in human nutrition and health. This paper provided comprehensive information on the mycological quality and mycotoxin safety of foods. The review showed that moulds are multicellular fungi that form thin thread like structures called hyphae. They are widely distributed and found wherever moisture is present with adequate nutrients that can sustain their growth. Fungi are major spoilage of foods and feedstuffs. The proliferation of various fungi in agricultural products leads to reduction in yield and quality with significant economic losses. Fungi produce secondary metabolites which are referred to as mycotoxins which have been found to be present in most food substances. The mycotoxins are low weight metabolites which cause harm known as mycotoxicoses, in livestock, domestic animals and humans and therefore of public health significance. The production of mycotoxins is stimulated by certain environmental factors: Therefore the extent of contamination will differ with geographic location, agricultural methods and the susceptibility of commodities to the penetration of fungi during storage and processing periods. Fungi that produce toxins in food are therefore classified into field fungi and storage fungi based on their ecological requirements for growth. Mycotoxins have been reported in several food products such as cereals, legumes, processed flour, and smoked-dried fish and in dried meats

Probing the exchange bias in Co/CoO nanoscale antidot arrays using anisotropic magnetoresistance

10.1103/PhysRevB.79.064413Physical Review B - Condensed Matter and Materials Physics796-PRBM

Binary ferromagnetic nanostructures: Fabrication, static and dynamic properties

10.1002/adfm.201201432Advanced Functional Materials23131684-1691AFMD

Functional magnetic waveguides for magnonics

Magnonics, or spin wave based spintronics, is an emerging technology where magnons—quanta for spin waves—process the information analogous to electronic charges in electronics. We introduce the fundamental components of a magnonic device and briefly discuss their electrical control. The magnetic waveguide—an integral part of a magnonic circuit—guides the spin wave signal (magnon current) of desired frequency, wave vector, phase, and amplitude, which are the key ingredients for wave based computing. Typically, a bias magnetic field aligns magnetization to satisfy anisotropic magnon dispersions for low-energy and long-wavelength magnons, and thus it hinders on-chip device integration capability. We discuss strategies to eliminate the requirements of such a bias field by utilizing self-biased waveguides, which are based on either exchange coupled magnetic multi-layer based magnetic micro-wire or dipolar coupled but physically separated chain of rhomboid nanomagnets. We emphasize that the self-biased waveguides offer additional functionalities as compared to conventional waveguides. In this regard, manipulation of spin waves or the gating operation is presented by utilizing reconfigurable remanent magnetic states of the waveguide externally controlled by field or microwave current. We discuss the prospects of these bias-free waveguide strategies in the rapidly developing field of nano-magnonics and their potential for practical realizations of a magnonic-electronic hybrid technology. © 2021 Author(s)