Evaluation of a Proposed Dust Ventilation/Collection System in an Underground Mine Crushing Plant

Computational Fluid Dynamics (CFD) modelling of a dust collection system in an underground mine crushing plant was carried out. Dust was collected/absorbed through the holes along the top edge of Run of Mine (ROM) bin. The dust collection performance of the system is summarised. The detail results are presented in the form of velocity vectors and dust concentration iso-surface contours. Time dependent dust concentration isosurfaces are also presented. Dust was found to be well contained within the crusher bin and stands out as a viable option. However, the velocity magnitudes were found to be very high in and around the whole exits, which has the potential to lead to undesirable pressure drop and generation of noise

Synthesis, characterization and urease inhibitory activities of Zn(II) complexes bearing C1-symmetric ligands derived from (R)-phenylethanamine

ABSTRACT. A series of Zn(II) complexes, supported with N-substituted phenylethanamine derivatives, [LnZnCl2] (where Ln = LA ((R)-1-phenyl-N-(thiophene-2-ylmethyl)ethanamine; LB (R)-N-(5-meyhylthiophene-2-yl)methyl-1-phenylethanamine; LC ((R)-N-(furan-2-ylmeththyl)-1-phenylethanamine and LD (R)-N-((5-methylfuran-2-yl)methyl)-1-phenylethanamine) were synthesized and characterized. The urease inhibitory activities of these complexes were determined against selected urease inhibitors where [LBZnCl2] was found to be the most prominent inhibitor of Jack bean urease (J. B. urease) (IC50 = 10.39±0.78 μM), whereas the activity of Bacillus pasteurii urease (B. P. urease) was predominantly inhibited by [LAZnCl2] (IC50 = 8.68±0.7 μM). Additionally, MOE-Dock program was used to affirm the probable binding modes of these complexes into the crystal structure of J. B. urease which certainly verified the inhibitory mechanism of these novel complexes.                     KEY WORDS: Zn(II) complexes, (R)-Phenylethanamine, Urease inhibition, Molecular docking   Bull. Chem. Soc. Ethiop. 2021, 35(2), 301-314. DOI: https://dx.doi.org/10.4314/bcse.v35i2.

Energy efficient residential house wall system

The energy consumption and greenhouse gas emission by the residential housing sector are considered to be one of the largest in economically developed countries. The larger energy consumption and greenhouse gas emission not only put additional pressure on finite fossil fuel resources but also cause global warming and climate change. Additionally, the residential housing sector will be consuming more energy as the house demand and average house floor area are progressively increasing. With currently used residential house wall systems, it is hard to reduce energy consumption for ongoing house space heating and cooling. A smart house wall envelope with optimal thermal masses and insulation materials is vital for reducing our increasing energy consumption. The major aim of this study is to investigate thermal performance and energy saving potential of a new house wall system for variable climate conditions. The thermal performance modelling was carried out using commercially developed software AccuRate®. The findings indicate that a notable energy savings can be accomplished if a smart house wall system is used

Secondary Fahr’s Disease: A Consequence of Post-Thyroidectomy Hypoparathyroidism

Objective: The objective of this case report is to emphasize the importance of considering uncommon conditions like Fahr’s disease in the differential diagnosis of seizures and cognitive impairment, especially in patients with a history of thyroidectomy. Material and Methods: A 56-year-old woman who had undergone subtotal thyroidectomy 25 years previously presented with movement disorder and cognitive impairment secondary to hypoparathyroidism. A CT scan of the brain showed pathognomonic bilateral calcification in the basal ganglia, thalamus and cerebellar nuclei. Result: The patient was diagnosed with Fahr’s disease caused by post-thyroidectomy hypoparathyroidism and successfully managed with oral calcium, carbidopa/levodopa and haloperidol. Conclusion: We recommend the routine use of CT scanning in the long-term follow-up of post-thyroidectomy patients

Epidural spinal cord compression from metastatic cancer: clinical features and management

We retrospectively analyzed thirty-three patients (21 males, 12 females) with malignancy induced spinal cord compression (SCC). The mean age of the patients was 42.8 years and almost half (51%) of them presented with SCC. Mean duration of symptoms was 4.5 months and the mean interval between the original diagnosis of cancer and the development of SCC was 14.6 months. Back pain was the most frequent (97%) symptom with an equal number of patients having subjective or objective evidence of lower limb weakness. Majority (73%) of the patients were non-ambulatory at the time of diagnosis. Spinal level involvement was mostly thoracic (62%) followed by lumber (38%). Breast cancer was the commonest underlying malignancy (21%). Lung (12%), prostrate (12%), multiple myeloma (9%), and carcinoma with unknown primary (12%) were also frequently encountered. There was an overall response rate of 22% to the therapeutic interventions: mostly observed in the ambulatory patients. Only 7% of the non-ambulatory patients regained ability to walk. None of the responders had bladder or bowel dysfunction. Twenty-two percent of the responders are still ambulatory with a mean follow-up of six months

Clinical features and management of malignant ascites

Retrospective analysis of 45 patients (33 females, 12 males) with cytologically-proven malignant ascites is presented. Abdominal pain was the most frequent symptom (69%). Fiftythree percent cases had low serum albumin. Ascitic fluid was haemorrhagic or serosanguinous in 48% cases, in the rest it was clear or straw-coloured. Peritoneal effusion was exudative in 84% cases. Mean glucose content of ascitic fluid was 95 mg/dl and the mean white cell count of 919 cells/cmm. Vast majority (82%) of the cases had metastatic adenocarcinomas. Primary malignancy was mostly ovarian (47%) followed by non-Hodgkin\u27s lymphoma (11%) and gall bladder carcinoma (9%). Primary site could not be identified in 13% cases. Sixty-two percent patients received systemic chemotherapy for the underlying malignancy, of these 43% had complete or partial resolution of the ascites. Of the patients whose long-term follow-up is available, 54% were alive with a median follow-up of 9 months

Piece-wise linear analog to digital (PLADC) converter process

Transducers are devices that transform energy from one form to another. Such transformation process may be applicable in the measurement of physical quantities, transfer of information and also in performing a certain control action. Transducers used as measuring devices are generally termed as sensors. Such transducers detect the changes in characteristics of a physical quantity and convert the change into a corresponding electrical signal. This is a common phenomenon when transducers are used to detect temperature, speed, force, liquid level or viscosity. On the other hand transducers, used to carry out control actions, are termed as actuators. These transducers usually convert an electrical signal into some form of physical control action such as heating or movement and are carried by the control devices. Various types of transducers exist meant for sensing and controlling different physical quantities. For example, a light dependent resistor (LOR) or a photodiode can be used to sense light intensity of an environment while lamps and LED displays can be used to control it. Likewise, a thermistor can be used to measure the temperature of an environment while a heater/fan can be used to control it and a tachometer can be used to measure the speed of a device while a stepper motor can be used to control it [1-3]. The focus of this chapter is on the problems and issues related to the interfacing of transducers when used as measuring devices or sensors in smart applications. Smart applications are also termed as tuned control for detecting changes in the parameter of interest which used to be ignorable in the traditional measurement and control system

Bifacial Si heterojunction-perovskite organic-inorganic tandem to produce highly efficient (η T * ~ 33%) solar cell

As single junction photovoltaic (PV) technologies both Si heterojunction (HIT) and perovskite based solar cells promise high efficiencies at low cost. Intuitively a traditional tandem cell design with these cells connected in series is expected to improve the efficiency further. Using a self-consistent numerical modeling of optical and transport characteristics however we find that a traditional series connected tandem design suffers from low JSC due to band-gap mismatch and current matching constraints. Specifically a traditional tandem cell with state-of-the-art HIT ( η=24% ) and perovskite ( η=20% ) sub-cells provides only a modest tandem efficiency of ηT~ 25%. Instead we demonstrate that a bifacial HIT/perovskite tandem design decouples the optoelectronic constraints and provides an innovative path for extraordinary efficiencies. In the bifacial configuration the same state-of-the-art sub-cells achieve a normalized output of η∗T  = 33% exceeding the bifacial HIT performance at practical albedo reflections. Unlike the traditional design this bifacial design is relatively insensitive to perovskite thickness variations which may translate to simpler manufacture and higher yield

A payload-based mutual authentication scheme for Internet of Things

The Internet of Things (IoT) is a vision that broadens the scope of the Internet by incorporating physical objects to identify themselves to the participating entities. This innovative concept enables a physical object to represent itself in the digital world. There have been a lot of speculations and future forecasts about these physical objects connected with the Internet, however, most of them lack secure features and are vulnerable to a wide range of attacks. Miniature sensor nodes, embedded in these physical objects, limit the support for computationally complex and resource-consuming secured algorithms. In this paper, we propose a lightweight mutual authentication scheme for the real-world physical objects of an IoT environment. It is a payload-based encryption scheme which uses a simple four-way handshake mechanism to verify the identities of the participating objects. The real-world objects communicate with each other using the client–server interaction model. Our proposed scheme uses the lightweight features of Constrained Application Protocol (CoAP) to enable the clients to observe resources residing on the server, in an energy-efficient manner. We use Advanced Encryption Standard (AES), with a key length of bits, to establish a secured session for resource observation. We evaluate our scheme for a real-world scenario using NetDuino Plus 2 boards. Our scheme is computationally efficient, incurs less connection overhead and at the same time, provides a robust defence against various attacks such as, resource exhaustion, Denial-of-Service, replay and physical tampering

Microwave-assisted green synthesis and antimicrobial activity of silver nanoparticles derived from a supercritical carbon dioxide extract of the fresh aerial parts of Phyllanthus niruri L

Purpose: To synthesize and evaluate the antimicrobial activity of silver nanoparticles (AgNPs) derived from a supercritical carbon dioxide extract of the fresh aerial parts of Phyllanthus niruri. Methods: The synthesis of AgNPs of a P. niruri extract was carried out in a microwave oven. The extraction was carried out using a supercritical fluid extractor. The AgNPs were characterized by the Ultraviolet-visible (UV-vis) spectral analysis, Dynamic Light Scattering (DLS) zetasizer analysis, Transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis and Fourier transform infrared (FT-IR) spectroscopy. The antimicrobial assays of AgNPs were carried out against different bacterial and fungal strains. Results: Results of various analytical techniques confirmed the synthesis of AgNPs of a P. niruri extract. The UV–vis spectroscopy showed an intense silver surface plasmon resonance band at 415 NM. The AgNPs had a mean size of 110 nm in the Zetasizer analysis. TEM images illustrated spherical AgNPs having a mean particle size of 110 nm. The X-ray diffractograms showed peaks at 38.17°, 44.28°, and 64.52°. The average crystallite size of Ag-NPs was found to be 110 nm. FT-IR spectra confirmed the stability of the AgNPs. The AgNPs demonstrated good antimicrobial effects against several tested pathogenic microbes. Conclusion: An efficiently synthesized AgNPs of P. niruri (SC-CO2) extract has been prepared by a simple, eco-friendly, cost-effective, rapid green chemistry methodology. The AgNPs of P. niruri extract possesses significant antimicrobial properties against the tested bacterial and fungal strains. Keywords: Nanoparticles, Phyllanthus niruri, Supercritical fluid extraction, Microwave, Antimicrobial activit