Three Degree of Freedom Acoustic Energy Harvester Using Improved Helmholtz Resonator

Izhar,Farid Ullah Khan 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.1

This paper presents the development of a broadband, multi-frequency acoustic energy harvester. The devised energy harvester contains an optimized Helmholtz resonator with conical cavity and a piezoelectric composite plate. The shape and dimensions of the resonator are selected based on the 3D pressure acoustics analysis in COMSOL Multiphysics®. In addition, a cantilever beam, made up of a brass base, a copper rod and a steel sheet, is integrated with the harvester’s piezoelectric plate to add an extra degree of freedom to the device. The developed harvester exhibited three peaks at 1501, 1766 and 1890 Hz frequencies, which correspond to the three resonant frequencies of the harvester. Furthermore, the harvester, when subjected to 130 dB sinusoidal SPL and 1501 Hz resonant frequency, generated a maximum power of 214.23 μW. However, when the harvester is operated under random (real) SPL in the vicinity of household electric generated, it produced about 250 and 265 mV output AC and DC voltage levels respectively.

An application of variogram modelling for electrical resistivity soundings to characterize depositional system and hydrogeology of Bannu Basin, Pakistan

Asam Farid,Perveiz Khalid,Khan Zaib Jadoon,Muhammad Asim Iqbal,James Small 한국지질과학협의회 2017 Geosciences Journal Vol.21 No.5

This study describes a method of combining geostatistical analysis with geophysical inversion of 1D electrical resistivity data acquired in the Bannu Basin, northwestern Himalayas of Pakistan. The data has been integrated and broadened from single dimension resistivity data into a 2D model that can be fully visualized and interpreted in a spatial sense. By interpreting and calibrating the electrical resistivity curves with the lithologies and geophysical logs of boreholes, it has been possible to identify unique sedimentary accumulations that occur throughout the basin. Through the use of variogram modelling the spatial extent of these accumulations can be identified and associated with measured hydraulic properties. It has become possible to map the extents and facies of the alluvial systems of the Bannu Basin formed during periods of heightened tectonic activity. The coarser sediments are associated with higher levels of resistivity as measured in the electrical surveys, whereas the finer sediments exhibit characteristically lower resistivities. Thus, the zones of high and low resistivity values become indicative of sediments associated with alluvial fans and lacustrine environments, respectively. The sediments of alluvial fans show relatively low gamma ray levels and higher transmissivities, whereas those of the piedmont deposits as well as lacustrine and sandy plains tend to show medium to high gamma ray values and lower transmissivities. Gross transmissivities were estimated by studying regression relationships between transmissivities measured in boreholes and the apparent formation factors of sediments. These relationships indicate an exponential increase in transmissivity with increasing apparent formation factor. These trends suggest a contrast in transmissivities between alluvial fan and other environments where lacustrine and sandy plains are characterized by low transmissivities. These estimated transmissivities do not represent absolute values but are merely indicative of any high or low trends in transmissivity of sediments, throughout the basin.

BOUNDS OF AN INTEGRAL OPERATOR FOR CONVEX FUNCTIONS AND RESULTS IN FRACTIONAL CALCULUS

Mishira, Lakshmi Narayan,Farid, Ghulam,Bangash, Babar Khan The Honam Mathematical Society 2020 호남수학학술지 Vol.42 No.2

The present research investigates the bounds of an integral operator for convex functions and a differentiable function f such that |f'| is convex. Further, these bounds of integral operators specifically produce estimations of various classical fractional and recently defined conformable integral operators. These results also contain bounds of Hadamard type for symmetric convex functions.

Salicylic acid and kinetin mediated stimulation of salt tolerance in cucumber (Cucumis sativus L.) genotypes varying in salinity tolerance

Ali Raza Gurmani,Sami Ullah Khan,Amjad Ali,Tehseen Rubab,Timothy Schwinghamer,Ghulam Jilani,Abid Farid,Jinlin Zhang 한국원예학회 2018 Horticulture, Environment, and Biotechnology Vol.59 No.4

Greenhouse studies were undertaken to evaluate the genetic performance of two cucumber genotypes (Long Green and Summer Green) at four salinity levels (0, 25, 50, and 100 mM NaCl). Seeds were pretreated with 50 mg salicylic acid (SA) L−1 and 25 mg kinetin (Kin) L−1. Under hydroponic conditions, seed pretreatment with Kin significantly increased shoot and root dry biomass and reduced the salt injury index in both genotypes. SA reduced the salt injury index of Long Green cucumbers. In a pot experiment, Kin treatment reduced Na+ and increased K+ concentration, photosynthesis, and chlorophyll content in both genotypes, compared to SA under saline soil conditions. Kin treatment improved fruit yield in both genotypes, while SA had a statistically significant effect on Long Green fruit yield. The application of SA and Kin enhanced salinity tolerance in both genotypes by the activation of antioxidants, especially superoxide dismutase, peroxidase, and catalase, which offset oxidative injury. Summer Green exhibited better salt tolerance and improved osmoregulation that resulted in higher fruit yield than Long Green. It was concluded that cucumber genotypes differed in salt tolerance, and seed pre-treatment with Kin minimized salt stress injury, even in sensitive genotype which could sustain crop production under saline conditions.

The Targon FN System for the Management of Intracapsular Neck of Femur Fractures: Minimum 2-Year Experience and Outcome in an Independent Hospital

Donald Osarumwense,Elizabeth Tissingh,Kakra Wartenberg,Saurabh Aggarwal,Fikry Ismail,Sam Orakwe,Farid Khan 대한정형외과학회 2015 Clinics in Orthopedic Surgery Vol.7 No.1

Background: The Targon FN implant was developed in 2007 to treat intracapsular neck of femur fractures. Early results from thedesign centre have shown good results in terms of fracture complications. We wished to see if these results can be reproduced inan independent institution. Methods: The records of consecutive patients, treated with this implant between 2008 and 2011 at Queen Elizabeth Hospital,were identified and collected for this study. Operations were performed by all grades of surgeons under supervision as appropriate. These patients went on to have both clinical and radiological assessment for fracture healing and function. Results: Fifty-one patients were identified with 43 patients available for final follow-up. The average age was 66 years with aminimum follow-up of 24 months. A non-union rate of 0% in the undisplaced fracture group and 1 in 12 (8%) in the displaced fracturegroup was observed. An avascular necrosis rate of 6% and 8% was observed for undisplaced and displaced fracture types,respectively. No significant change in premorbid to postoperative ambulation was observed and there was no wound complication. Conclusions: Our study shows similar results with those of the design centre and which are superior to those currently found inthe literature for the more traditional fixation methods. It also shows that the promising results with this new implant as seen fromthe design institutions can be reproduced by all cadres of surgeons in non-specialist practice.

Fabrication of a three-dimensional bone marrow niche-like acute myeloid Leukemia disease model by an automated and controlled process using a robotic multicellular bioprinting system

Dana M. Alhattab,Ioannis Isaioglou,Salwa Alshehri,Zainab N. Khan,Hepi H. Susapto,Yanyan Li,Yara Marghani,Arwa A. Alghuneim,Rubén Díaz-Rúa,Sherin Abdelrahman,Shuroug AL-Bihani,Farid Ahmed,Raed I. Felim 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00

Background Acute myeloid leukemia (AML) is a hematological malignancy that remains a therapeutic challenge due to the high incidence of disease relapse. To better understand resistance mechanisms and identify novel therapies, robust preclinical models mimicking the bone marrow (BM) microenvironment are needed. This study aimed to achieve an automated fabrication process of a three-dimensional (3D) AML disease model that recapitulates the 3D spatial structure of the BM microenvironment and applies to drug screening and investigational studies. Methods To build this model, we investigated a unique class of tetramer peptides with an innate ability to selfassemble into stable hydrogel. An automated robotic bioprinting process was established to fabricate a 3D BM (niche-like) multicellular AML disease model comprised of leukemia cells and the BM’s stromal and endothelial cellular fractions. In addition, monoculture and dual-culture models were also fabricated. Leukemia cell compatibility, functionalities (in vitro and in vivo), and drug assessment studies using our model were performed. In addition, RNAseq and gene expression analysis using TaqMan arrays were also performed on 3D cultured stromal cells and primary leukemia cells. Results The selected peptide hydrogel formed a highly porous network of nanofibers with mechanical properties similar to the BM extracellular matrix. The robotic bioprinter and the novel quadruple coaxial nozzle enabled the automated fabrication of a 3D BM niche-like AML disease model with controlled deposition of multiple cell types into the model. This model supported the viability and growth of primary leukemic, endothelial, and stromal cells and recapitulated cell-cell and cell-ECM interactions. In addition, AML cells in our model possessed quiescent characteristics with improved chemoresistance attributes, resembling more the native conditions as indicated by our in vivo results. Moreover, the whole transcriptome data demonstrated the effect of 3D culture on enhancing BM niche cell characteristics. We identified molecular pathways upregulated in AML cells in our 3D model that might contribute to AML drug resistance and disease relapse. Conclusions Our results demonstrate the importance of developing 3D biomimicry models that closely recapitulate the in vivo conditions to gain deeper insights into drug resistance mechanisms and novel therapy development. These models can also improve personalized medicine by testing patient-specific treatments.