Currently, researchers turn to natural processes such as using biological microorganisms in order to develop reliable and ecofriendly methods for the synthesis of metallic nanoparticles. In this study, we have investigated extracellular biosynthesis of silver nanoparticles using four Aspergillus species including A. fumigatus, A. clavatus, A. niger, and A. flavus. We have also analyzed nitrate reductase activity in the studied species in order to determine the probable role of this enzyme in the biosynthesis of silver nanoparticles. The formation of silver nanoparticles in the cell filtrates was confirmed by the passage of laser light, change in the color of cell filtrates, absorption peak at 430 nm in UV-Vis spectra, and atomic force microscopy (AFM). There was a logical relationship between the efficiencies of studied Aspergillus species in the production of silver nanoparticles and their nitrate reductase activity. A. fumigatus as the most efficient species showed the highest nitrate reductase activity among the studied species while A. flavus exhibited the lowest capacity in the biosynthesis of silver nanoparticles which was in accord with its low nitrate reductase activity. The present study showed that Aspergillus species had potential for the biosynthesis of silver nanoparticles depending on their nitrate reductase activity.

ReuseUnless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. Overall, detection accuracy was 99.78% for all the events in both groups. Based on the validated results, the proposed system can be used to accurately detect the temporal gait events in real-time that leads to the detection of gait phase system and therefore, can be utilized in gait analysis applications and the control of lower limb prostheses.

No abstract

Abstract-Gait event detection is important for intent predication in lower limb prostheses and exoskeletons during different activities. Human gait cycle is divided into two main phases i.e. swing phase and stance phase. Initial contact (IC) with the ground indicate the start of stance phase while Toe Off (TO) is the start of swing phase. This article presents algorithm based on set of heuristic rules for gait event detection using a single gyroscope attached on shank of subjects performing activities of daily living such as normal walking, fast walking, ramp ascending and ramp descending. The algorithm sequentially detected gait events like IC, TO, Midswing (MSw) and Midstance (MSt). Results were compared with the reference pressure measurement system using Flexiforce footswitches (FSW). The mean difference error between the reference and proposed system was for IC is about +4ms and for TO is about -6.5ms. The results showed that proposed algorithm achieved high detection performance compared to the existing algorithms and will lead to powerful tool to develop an intent recognition system for lower limb amputees. I. INTRODUCTIONLocomotion is crucial for human during activities of daily living (ADLs) as it plays an important role in gait efficiency and task progression. Patients with pathologic gait suffer from higher energy consumption and risk of falls. Gait analysis and event detection has been used in different applications using ambulatory gait systems to evaluate and improve patients' motilities and to control the functional electrical stimulation (FES) [1][2][3].Gait events can be detected using either force based measurement systems by means of footswitches such as force sensitive resistors (FSR) [4], or wearable sensor such as Inertia Measurement Unit (IMU) [5]. To perform outdoor activities for longer period of time, it is crucial to use the systems which are reliable, portable, small, inexpensive, and with low power consumption [6][7][8].Many researchers have used wearable sensors (accelerometers and gyroscopes) for analysis of spatiotemporal gait parameters during ADLs [9,[20][21]. Gyroscopes have been applied for detecting the gait events for triggering [10] amputees [20]. Locating the gyroscope on shank has many advantages as opposed to other parts of the human body [12], such as less soft tissue muscles at shank compared to thigh. In addition, gyroscope placed at shank is acceptable accurately in healthy and pathological subjects [13,14].Sabatini et al.[15] developed a gait event detection system for analysis of incline walking based on a single gyroscope attached on the foot of healthy subjects. However, placing gyroscope on shank provides ease of use as compared to its placement on foot as it provides less signal variability between the subjects. P. Catalfamo et al.[16] used a single gyroscope placed on the shank for detection of initial contact (IC) and foot off (FO) in subjects walking up and down on inclined surface and level ground. The results were compared with a reference system of foot ...

Background. Spices are one of the flavoring components of food in the cooking recipes of different nations that are used daily. However, these ingredients may be contaminated by toxicogenic fungi and subsequent production of mycotoxins that cannot be neutralized through cooking. In the present study, the possible contamination of spices by aflatoxins (AFs) and ochratoxin A (OTA) was investigated from Shiraz, the south part of Iran. Materials and Methods. A total of 80 spice samples including turmeric (n = 20), red pepper (n = 20), black pepper (n = 20), and cinnamon (n = 20) were purchased from markets and cultured on appropriate medium. The isolated fungi were identified. Simultaneously, mycotoxins from spices were extracted with immunoaffinity columns (IAC) and the occurrence of AFs (B1 + B2 + G1 + G2) and OTA was then determined using high-performance liquid chromatography (HPLC) with a fluorescence detector (FD). Result. The results depicted that 40 spice samples were contaminated with AFs and 48 samples with OTA. The highest rate of AFs contamination was related to red pepper, in 80% of which the amount of contamination was excessive than the standard level (>10 μg/kg). All black pepper samples were determined to be contaminated with OTA at over legislation limits of >15 μg/kg. Aspergillus species were the predominant isolated fungi, followed by Penicillium, and Mucor species. Discussion. Regarding the high mycotoxins contamination in spices in the current study, regular effective surveillance and quality control procedures are highly recommended. To achieve this goal, it is necessary to empower food-related laboratories with precise methods of isolation and detection of mycotoxins.

Keratin was extracted from chicken feather to produce scaffolds with poly(3-hydroxybutyrate) (P(3HB)) for tissue engineering applications. The scaffolds with different concentrations (10%, 20%, and 30%) of keratin were produced by electrospinning. The keratin presence in the produced scaffold was confirmed by FTIR analysis. The surface wettability of the P(3HB)/keratin scaffold was much higher compared to neat P(3HB) scaffold because of hydrophilic nature of the keratin. All the scaffolds showed over 80% porosity with an average fiber diameter of less than 750 nm. Mechanical properties of the P(3HB) scaffolds with up to 20% keratin were superior compared to neat P(3HB) scaffold. However, the mechanical properties of the P(3HB)/keratin scaffolds were deteriorated when the keratin concentration was 30% in the scaffold. The observed mechanical properties reduction was mainly attributed to the poor interaction between the keratin and P(3HB) matrix. Due to better biocompatibility of keratin, cell culture studies suggested that the P(3HB)/ keratin scaffolds can have better cell attachment and proliferation compared to the neat P(3HB) scaffold. Owing to good biological response and mechanical properties, the P(3HB)/keratin scaffolds with an optimal concentration of keratin (20%) could be used as potential material for tissue engineering application.

No abstract

No abstract