ABSTRACT
PURPOSE: To manufacture and test 3D printed novel design titanium spine rods with lower flexural modulus and stiffness compared to standard solid titanium rods for use in metastatic spine tumour surgery (MSTS) and osteoporosis. METHODS: Novel design titanium spine rods were designed and 3D printed. Three-point bending test was performed to assess mechanical performance of rods, while a French bender was used to assess intraoperative rod contourability. Furthermore, 3D printed spine rods were tested for CT & MR imaging compatibility using phantom setup. RESULTS: Different spine rod designs generated includes shell, voronoi, gyroid, diamond, weaire-phelan, kelvin, and star. Tests showed 3D printed rods had lower flexural modulus with reduction ranging from 2 to 25% versus standard rod. Shell rods exhibited highest reduction in flexural modulus of 25% (~ 77.4 GPa) and star rod exhibited lowest reduction in flexural modulus of 2% (100.8GPa). 3D printed rod showed reduction in stiffness ranging from 40 to 59%. Shell rod displayed highest reduction in stiffness of 59% (179.9 N/mm) and gyroid had least reduction in stiffness of 40% (~ 259.2 N/mm). Rod bending test showed that except gyroid, other rod designs demonstrated lesser bending difficulty versus standard rod. All 3D printed rods demonstrated improved CT/MR imaging compatibility with reduced artefacts versus standard rod. CONCLUSION: By utilising novel design approach, we successfully generated a spine rod design portfolio with lower flexural modulus/stiffness profile and better CT/MR imaging compatibility for potential use in MSTS/other conditions such as osteoporosis. Thus, exploration of new rod designs in surgical application could enhance treatment outcome and improve quality of life for patients.
Subject(s)
Quality of Life , Titanium , Humans , Spine/diagnostic imaging , Spine/surgery , Printing, Three-Dimensional , Materials TestingABSTRACT
PURPOSE: To develop a novel 3D printable polyether ether ketone (PEEK)-hydroxyapatite (HA)-magnesium orthosilicate (Mg2SiO4) composite material with enhanced properties for potential use in tumour, osteoporosis and other spinal conditions. We aim to evaluate biocompatibility and imaging compatibility of the material. METHODS: Materials were prepared in three different compositions, namely composite A: 75 weight % PEEK, 20 weight % HA, 5 weight % Mg2SiO4; composite B: 70 weight% PEEK, 25 weight % HA, 5 weight % Mg2SiO4; and composite C: 65 weight % PEEK, 30 weight % HA, 5 weight % Mg2SiO4. The materials were processed to obtain 3D printable filament. Biomechanical properties were analysed as per ASTM standards and biocompatibility of the novel material was evaluated using indirect and direct cell cytotoxicity tests. Cell viability of the novel material was compared to PEEK and PEEK-HA materials. The novel material was used to 3D print a standard spine cage. Furthermore, the CT and MR imaging compatibility of the novel material cage vs PEEK and PEEK-HA cages were evaluated using a phantom setup. RESULTS: Composite A resulted in optimal material processing to obtain a 3D printable filament, while composite B and C resulted in non-optimal processing. Composite A enhanced cell viability up to ~ 20% compared to PEEK and PEEK-HA materials. Composite A cage generated minimal/no artefacts on CT and MR imaging and the images were comparable to that of PEEK and PEEK-HA cages. CONCLUSION: Composite A demonstrated superior bioactivity vs PEEK and PEEK-HA materials and comparable imaging compatibility vs PEEK and PEEK-HA. Therefore, our material displays an excellent potential to manufacture spine implants with enhanced mechanical and bioactive property.
Subject(s)
Durapatite , Polyethylene Glycols , Humans , Durapatite/pharmacology , Polymers , KetonesABSTRACT
Integrating geometric and diffractive optics functions is urgently needed to develop compact equipment for integrating diffraction manipulation and arrayed outputs. In this Letter, a superimposed three-level-grooved surface is proposed to manipulate the diffraction of visible light and provide an array output. Structure design, vibration-assisted fly-cutting, finite-difference time-domain calculations, and diffraction tests are conducted to fabricate the three-level grooves and explore the diffraction mechanism. Nanogrooves with a period close to the middle wavelength of the spectrum primarily enhances the diffraction at low diffraction orders and angles because of resonance. Optical tests prove that these superimposed three-level nanogrooves have a large bandwidth when providing the array output and serving to control and transmit diffracted light. They also show stronger performance for manipulating low diffraction orders.
ABSTRACT
Mangroves are the highly productive and extensive ecosystem in the tropical coasts. Chlorophyll is the key foliar determinant of mangrove productivity. Optical characteristics of mangrove markedly differ from land vegetation; hence, defining narrowband spectral indices most sensitive to mangrove chlorophyll is crucial, in view of their importance to the coastal environment and mounting biotic pressures. We assessed the sensitivity of a set of satellite hyperspectral remote sensing indices to mangrove canopy chlorophyll in Middle Andaman Island, India, and propose most robust spectral indices for mangrove chlorophyll estimation. We generated simple, modified simple, normalized difference vegetation, and non-linear indices from all possible two band combinations of EO-1 Hyperion bands in the 500-900 nm spectral range. The strength of correlation between each pair of spectral indices to mangrove chlorophyll was analyzed in 2D correlograms and validated using k-fold cross-validation technique. Results show that 549 nm, 559 nm (green) and 702 nm, 722 nm, 742 nm, and 763 nm (red-edge) wavelengths are the most sensitive to mangrove chlorophyll. We report performance of traditional chlorophyll indices and new indices with higher predictive capability for mangrove chlorophyll prediction. Simple ratio (559 nm/885 nm) offered the strongest correlation with mangrove chlorophyll (R2-0.75, RMSE-0.60, p < 0.05). Study findings will help researchers in deciding suitable chlorophyll indices for mangrove productivity and stress assessment. The best calibrated index was used to prepare mangrove chlorophyll spatial variability map of the study area.
Subject(s)
Chlorophyll , Ecosystem , Chlorophyll/antagonists & inhibitors , Chlorophyll/chemistry , Environmental Monitoring , India , Plant Leaves , Spectrum AnalysisABSTRACT
India is home of the largest remaining population of the Asian elephant (Elephas maximus L.) in the South and Southeast Asia. The forest loss and fragmentation is the main threat to the long-term survival of Asian elephants. In the present study, we assessed forest loss and fragmentation in the major elephant ranging provinces in India, viz., north-eastern, north-western, central, and southern since the 1930s. We quantified forest cover changes by generating and analyzing forest cover maps of 1930, 1975, and 2013, whereas fragmentation of contiguous forest areas was quantified by applying landscape metrics on the temporal forest cover maps. A total of 21.49% of the original forest cover was lost from 1930 to 1975, while another 3.19% forest cover was lost from 1975 to 2013 in the elephant ranges in India. The maximum forest loss occurred in the southern range (13,084 km2) followed by north-eastern (10,188 km2), central (5614 km2), and north-western (4030 km2) elephant ranges in the past eight decades. The forests in the central range were the most fragmented followed by southern, north-eastern, and north-western elephant ranges. The forest fragmentation in the southern range occurred at the fastest rate than central, north-eastern, and north-western ranges. The core forest areas shrunk by 39.6% from 1930 to 2013. The causative factors of forest change and situation of elephant-human conflict have been discussed. Study outcomes would be helpful in planning effective conservation strategies for Asian elephants in India.
Subject(s)
Conservation of Natural Resources , Elephants , Forests , Animals , Environmental Monitoring , Feeding Behavior , Humans , IndiaABSTRACT
Wind energy is one of the extraordinary sources of renewable energy due to its clean character and free availability. With the increasing wind power penetration, the wind farms are directly influencing the power systems. The majority of wind farms are using variable speed wind turbines equipped with doubly fed induction generators (DFIG) due to their advantages over other wind turbine generators (WTGs). Therefore, the analysis of wind power dynamics with the DFIG wind turbines has become a very important research issue, especially during transient faults. This paper presents fuzzy logic control of doubly fed induction generator (DFIG) wind turbine in a sample power system. Fuzzy logic controller is applied to rotor side converter for active power control and voltage regulation of wind turbine.
Subject(s)
Power Plants , Renewable Energy , Wind , Power Plants/instrumentation , Power Plants/standardsABSTRACT
In this research work, we have successfully synthesized the CeO2/Co3O4/g-C3N4 ternary nanocomposite for hydrothermal method for photocatalytic applications. The synthesized nanocomposites were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Field emission scanning electron microscopy (FE-SEM), Transmission electron microscopy TEM, Photoluminescent spectra (PL), X-ray photoelectron spectroscopy (XPS), Brunauer- Emmett-Teller (BET) and Ultraviolet diffuse reflectance spectroscopy (UV-DRS) technique. As per the optical spectroscopic investigations CeO2/Co3O4/g-C3N4 ternary nanocomposite exhibited the high optical absorption range and its band gap is reduced from 2.95 eV to1.83 eV. The PL spectra showed the lowered emission peak intensity of ternary nanocomposite which is revealed that the better charge separation and slow recombination of electron hole pairs. The highest photocatalytic degradation efficiency of CeO2/Co3O4/g-C3N4 ternary nanocomposite showed 93 % and 86 % towards the pollutant methylene blue and Rhodamine B. Moreover, photodegradation of the pollutants followed pseudo-first order kinetics with a very high-rate constant of 0.02211 min-1 and 0.017756 min-1. Additionally, the ternary nano catalyst was delivered the remarkable stability performance even after five cycles. This research may provide a low-cost approach for synthesized visible light responsive catalysts for use in environmental remediation applications.
ABSTRACT
It has become a scientific obligation to unveil the underlying mechanisms and the fabrication methods behind wearable/stretchable strain sensors based on intelligent nanomaterials in order to explore their possible potential in the field of biomedical and healthcare applications. This report is based on an extensive literature survey of fabrication of stretchable strain sensors (SSS) based on nanomaterials in the fields of healthcare, sports, and entertainment. Although the evolution of wearable strain sensors (WSS) is rapidly progressing, it is still at a prototype phase and various challenges need to be addressed in the future in special regard to their fabrication protocols. The biocalamity of COVID-19 has brought a drastic change in humans' lifestyles and has negatively affected nations in all capacities. Social distancing has become a mandatory rule to practice in common places where humans interact with each other as a basic need. As social distancing cannot be ruled out as a measure to stop the spread of COVID-19 virus, wearable sensors could play a significant role in technologically impacting people's consciousness. This review article meticulously describes the role of wearable and strain sensors in achieving such objectives.
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Lattice structures are widely used in orthopedic implants due to their unique features, such as high strength-to-weight ratios and adjustable biomechanical properties. Based on the type of unit cell geometry, lattice structures may be classified into two types: strut-based structures and sheet-based structures. In this study, strut-based structures (Cubic & Octet) and sheet-based structure (triply periodic minimal surface (TPMS) gyroid) were investigated. The biomechanical properties of the three different Ti6Al4V lattice structures fabricated by selective laser melting (SLM) were investigated using room temperature compression testing. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to check the 3D printing quality with regards to defects and quantitative compositional information of 3D printed parts. Experimental results indicated that TPMS gyroid has superior biomechanical properties when compared to Cubic and Octet. Also, TPMS gyroid was found to be less affected by the variations in relative density. The biocompatibility of Ti6Al4V lattice structures was validated through the cytotoxicity test with human osteoblast-like SAOS2 cells. The debris generated during the degradation process in the form of particles and ions is among the primary causes of implant failure over time. In this study, Ti6Al4V particles with spherical and irregular shapes having average particle sizes of 36.5 µm and 28.8 µm, respectively, were used to mimic the actual Ti6Al4V particles to understand their harmful effects better. Also, the effects and amount of Ti6Al4V ions released after immersion within the cell culture media were investigated using the indirect cytotoxicity test and ion release test.
Subject(s)
Lasers , Osteoblasts , Alloys , Humans , Materials Testing , Porosity , TitaniumABSTRACT
AIM: The aim of the study was to find the suitable situation for the fixation of "six" hole miniplates in open reduction and internal fixation of displaced and nondisplaced unilateral angle of the mandible fractures. SUBJECTS AND METHODS: Displaced, nondisplaced, simple, compound (linear and noncomminuted) isolated unilateral angle fractures with or without occlusal derangement were included in this study. STATISTICAL ANALYSIS USED: Chi-square test was used for the statistical analysis. RESULTS: The parameters assessed preoperatively and postoperatively were mouth opening, occlusion, neurosensory deficit such as paresthesia, intraoperative time, stability of fragments, and access to the retromolar trigone which showed that the six-hole titanium miniplate was clinically useful in special clinical situations when compared to four-hole titanium miniplate. CONCLUSION: To conclude, six-hole titanium miniplate was clinically useful when compared to four-hole titanium miniplate in the following special clinical situations such as bone loss following extraction of third molar, no posterior occlusion and instability of fracture moderately displaced fracture needs more stability.
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We present a liquid tunable diffractive/refractive hybrid lens fabricated through what we believe to be a novel process that combines single-point diamond turning with soft lithography techniques. The hybrid lens achieves focal length tunability by changing its shape and, at the same time, utilizes the unique dispersion property of diffractive surfaces to enhance its spectral performance within a wide tuning range.
ABSTRACT
With the use of diamond cutting processes, namely turning and shaping, followed by soft lithography with polydimethylsiloxane, a liquid tunable double-focusing lens is fabricated. Data from a mechanical profiler verified that the dimensions of the features of the lens device adhere well to designed values. In addition, atomic force microscopy results show that this method of fabrication is able to produce multiple replicas of the lens device with a high-quality surface finish that is suitable for optical purposes. Lastly, the tunability of the lens is demonstrated, with experimental results agreeing well with simulation results.
ABSTRACT
Bioinsecticide Bacillus thuringiensis var. kurstaki (Btk) was used for controlling the mosquito species (Anopheles stephensi and Culex quinquefasciatus) which gave a significant (p<0.05) mortality in both species. The higher concentration of Btk was highly effective compared to the control ones. The controlling effect was dose and time dependent. Among the studied mosquitoes the C. quinquefasciatus (LC5 0.154%) was more susceptible than A. stephensi (LC50 0.372%) towards the bioinsecticide Btk.
Subject(s)
Anopheles , Bacillus thuringiensis , Culex , Pest Control, Biological , Animals , Anopheles/growth & development , Culex/growth & development , Larva , Toxicity TestsABSTRACT
Coriandrum sativum (Coriander) has been documented as a traditional treatment for cholesterol and diabetes patients. In the present study, coriander seeds incorporated into diet and the effect of the administration of coriander seeds on the metabolism of lipids was studied in rats, fed with high fat diet and added cholesterol. The seeds had a significant hypolipidemic action. In the experimental group of rats (tissue) the level of total cholesterol and triglycerides increased significantly There was significant increase in beta-hydroxy, beta-methyl glutaryl CoA reductase and plasma lecithin cholesterol acyl transferase activity were noted in the experimental group. The level of low density lipoprotein (LDL) + very low density lipoprotein (VLDL) cholesterol decreased while that of high density lipoprotein (HDL) cholesterol increased in the experimental group compared to the control group. The increased activity of plasma LCAT enhanced degradation of cholesterol to fecal bile acids and neutral sterols appeared to account for its hypocholesterolemic effect.
Subject(s)
Anticholesteremic Agents/pharmacology , Cholesterol, VLDL/blood , Coriandrum/chemistry , Lipid Metabolism/drug effects , Seeds/chemistry , Animals , Body Weight/drug effects , Female , Lipoproteins, HDL/blood , Lipoproteins, LDL/blood , Rats , Rats, Sprague-Dawley , SpicesABSTRACT
In the past decade, a rich repertoire of soft robots, designed from biomimetic and intuitive approaches, has been developed to overcome challenges faced by their rigid-bodied counterparts. However, these design approaches are greatly limited by the designers' experience and inspiration. In this article, the structural design problem is mathematically modeled under the framework of topology optimization, and solved by a new implementation tool that combines Abaqus/CAE and Matlab coding. Herein, a pneumatic soft gripper with two identical fingers was developed as a practical application. To fulfill the grasping task, each gripper finger is optimized to achieve its maximal bending deformation. The optimized gripper fingers are in high consistence with human fingers as indicated by pseudo-joints. Thereafter, the optimized gripper fingers are directly fabricated by three-dimensional printing technique with unprecedented fidelity regardless of high geometric complexity. Experimental results show that the gripper can grasp an elastic balloon, and each gripper finger is able to undergo a [Formula: see text] free travel bending and exert 0.23 N grasping force upon 0.06 MPa actuation pressure. The proposed approach is freely extendable to develop other types of soft robots and this represents an important step toward the goal of designing and fabricating soft robots automatically.
Subject(s)
Biomimetics/methods , Fingers/physiology , Printing, Three-Dimensional , Robotics/methods , Humans , Models, TheoreticalABSTRACT
Precision goniometry using optics has the advantage that it does not impose much stress on the object of investigation and, as such, is adopted extensively in gravitational wave detection, in torsion balances investigating fundamental forces, in specialized studies of biological samples, and it has potential applications in condensed matter physics. In this article we present the considerations that go into designing optical levers and discuss the performance of the instrument we have constructed. We motivate the design by considering an idealized setup and the limitations to the angular resolution induced by statistical fluctuations of the photon count rate and diffraction at the apertures. The effects of digitization of the count rate and of the spatial location of the photons on the image plane motivating the actual design are discussed next. Based on these considerations, we have developed an autocollimating optical lever which has a very high resolution and dynamic range. An array of 110 slits, of 90 microm width and a pitch of 182 microm, is located in the focal plane of a field lens, of focal length 1000 mm, and is illuminated by a CCFL tube. This array is imaged back onto the focal plane after retroreflection from a mirror placed just beyond the lens. The image is recorded on a linear charge-coupled device array at the rate of 1000 images/s and is processed through a special algorithm to obtain the centroid. The instrument has a centroid stability of approximately 3 x 10(-10) rad Hz(-1/2) and a dynamic range of approximately 10(7).
Subject(s)
Arthrometry, Articular/instrumentation , Optics and Photonics/instrumentation , Equipment Design , Humans , Mathematical ComputingABSTRACT
INTRODUCTION: Cholesterol lowering activity of Mangifera indica L. has been determined by earlier researchers and kernel, leaf and bark have shown significant activity. However, the specific cholesterol lowering activity of leaf methanol extract has not been determined. MATERIALS AND METHODS: The present study involved evaluation of cholesterol lowering potential of methanol extract of M. indica leaves using high cholesterol diet model in albino Wistar rats. The acute oral toxicity at a dose of 5000 mg/ kg body weight was also determined in female albino Wistar rats. Phytoconstituents Iriflophenone 3-C-ß-D-glucoside and mangiferin were quantified in methanol extracts of different varieties of mango leaves using high performance liquid chromatography. RESULTS AND DISCUSSION: Significant cholesterol lowering activity was observed with methanol extract of M. indica leaves, at dose of 90 mg/kg body weight in rats and it was also found to be safe at dose of 5000 mg/kg rat body. Iriflophenone 3-C-ß-D-glucoside and mangiferin were found to be in the range of 1.2 to 2.8% w/w and 3.9 to 4.6% w/w, respectively which along with 3 ß taraxerol and other sterols could be contributing to the cholesterol lowering activity of mango leaves extract. CONCLUSIONS: The phytosterols rich extract of Mangifera indica leaves is a good source of nutraceutical ingredient that have the potential to lower serum cholesterol levels. SUMMARY: The Mangifera indica leaves methanolic extract showed significant cholesterol lowering activity in high cholesterol diet induced hypercholesterolaemia model in rats when evaluated at a dose of 90 mg/kg rat body weight. The extract was found to contain Iriflophenone 3-C-ß-D-glucoside and mangiferin which along with 3 ß taraxerol and other sterols could be contributing to the cholesterol lowering activity.
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OBJECTIVE: To evaluate the role of Resistive index measured by cranial doppler ultrasonography in predicting the risk of death/ abnormal neurodevelopmental outcomes in term neonates with hypoxic ischemic encephalopathy. METHODS: We enrolled 50 term asphyxiated neonates with hypoxic ischemic encephalopathy and measured resistive index within 72 hours from the anterior cerebral artery. Participants underwent tone and developmental assessment at 6-12 months. RESULTS: Among the 50 neonates, 25 (50%) had abnormal resistive index (<0.56 or >0.80). Presence of abnormal resistive index increased the risk of death/ abnormal neurological outcomes at 6-12 months [RR (95% CI): 7.5 (2.0,8.6), P<0.01]. CONCLUSION: An abnormal resistive index is associated with death/ neurodevelopmental impairment in neonatal hypoxic ischemic encephalopathy.
Subject(s)
Brain/diagnostic imaging , Hypoxia-Ischemia, Brain/diagnostic imaging , Ultrasonography, Doppler, Transcranial , Brain/blood supply , Female , Humans , Hypoxia-Ischemia, Brain/mortality , Infant, Newborn , Male , Prognosis , Prospective Studies , Treatment OutcomeABSTRACT
The essential oil from the leaves of Feronia limonia was extracted and the chemical constituents and antibacterial activity were studied. The GC and GC-MS analyses revealed that the leaf essential oil of F. limonia contained fourteen compounds representing about 98.4% of the total oil. The major chemical compounds identified were Eudesma-4 (14).11-dine (46.3%), carvacrol (29.6%) and 1,5-cyclodecandine (13.4%). The essential oil was screened for its antibacterial activity against different clinically isolated Gram positive and Gram negative bacterial strains by disc diffusion and minimum inhibitory concentration assay. The essential oil exhibited moderate antibacterial activity against all the tested bacterial strains with MIC values ranging from 125 to 500 µg/mL except Proteus mirabilis.
ABSTRACT
Cranioplasty is the procedure that repairs holes or defects in the skull with cranial implants. When the bone from the hole is missing, damaged, or infected, the defect needs to be covered with an artificial plate to protect the brain. In this paper, a hole-repairing algorithm is developed to aid in shaping artificial plates for Cranioplasty, by describing a method for filling holes in defective biomodels with unstructured triangular surface meshes or in stereo-lithography format. The resulting patching meshes interpolate the shape and density of the surrounding mesh. The steps in repairing a hole include hole identification, hole triangulations using Genetic Algorithm optimization, and a customized advancing-front meshing technique using surface approximations based on a Quartic Bézier patch/surface.