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Reliability of the Panoramic Imaging Compared to Cone-beam Computed Tomography in Determining the Relationship of the Third Molar to the Mandibular Canal
No full textBackground: The incidence of injury to the inferior alveolar nerve during mandibular molar extraction increased the demand for pre-surgical planning to avoid any complications. Aim: To investigate the diagnostic accuracy of the dental panoramic image compared to cone-beam computed tomo graphy (CBCT) in predicting the inferior alveolar nerve (IAN) exposure during impacted third molar extraction. Materials and methods: This is a prospective study of consecutive patients, consulted for third molar extraction under local anesthesia. Thirty-two patients showed sign of proximity of the roots of the third molars to the mandibular canal from the dental panoramic image, were selected for CBCT. Results: With respect to the interobserver reliability, no significant difference (p < 0.05) was observed for the prediction on nerve exposure and injury from the dental panoramic image, however, showed a significant difference (p = 0.001) for the cone-beam computed tomography. The prevalence of contact between the third molar to the inferior alveolar canal (IAC) was 96.8% with a significant finding p = 0.002. There was a significant difference in the loss of cortex in predicting nerve exposure with p = 0.04. Clinically, three patients had nerve exposure and two patients had neurosensory disturbances. Conclusion: Dental panoramic image is still valuable for predicting the proximity of the third molar to the inferior alveolar canal. Nevertheless, CBCT has the best precision in localizing the close contact between the third molar and the inferior alveolar canal. Clinical significance: There was no significant finding from the CBCT for the incidence of the inferior alveolar nerve exposure and injury. However, it was seen to be accurate in predicting the IAN exposure. All these findings prove that cone-beam computed tomography contributes in the surgical plan, reduced operative time and patient morbidity
A review on laser beam welding of titanium alloys
No full textIn recent years, there is an increased in used of titanium alloys for some parts of mass-produced automobiles and aerospace. However, titanium alloys are characterized by difficult machinability, high melting temperature, high strength, low thermal conductivity, and high reactivity to oxygen, which overshadowed conventional manufacturing processes. To this end, there is a pressing need for more efficient technologies for the manufacture of low-cost titanium structures. Over the years, several joining techniques have been considered for fabrication of titanium alloys. Nevertheless, laser beam welding presents a viable option for welding of titanium due its versatility, high specific heat input, and flexibility. To date, under optimum processing conditions, the strength of the laser-welded titanium alloys can be close to the original material; however, there are still some processing problems such as lower elongation and corrosion resistance coupled with inferior fatigue properties. In this document, the laser beam welding of similar and dissimilar titanium alloys is reviewed, focusing on the influence of the processing parameters, microstructure-property relationship, metallurgical defects, and possible remedies
Drying Shrinkage Strain of Palm-oil by-products Lightweight Concrete: A Comparison between Experimental and Prediction Models
No full textDrying shrinkage in concrete can be attributed to loss of moisture, variations in temperature, and the chemical reactions of cement with water and carbon dioxide, is one of the most important parameters which affects the durability and service life of the concrete structures. Recently, the lightweight concrete has got a considerable attention to be used in structural applications. Although, this concrete has very high drying shrinkage compared to conventional concrete. Therefore, the design engineers need an accurate and precise estimation of the concrete shrinkage, so that the safe and durable structure can be produced. The main objective of this research is to compare the development of drying shrinkage strain of three concrete mixes made of by-product aggregate namely oil pam shell and oil-palm-boiler clinker from the palm oil industry with the prediction models. For that purpose, ten (ACI209R, EN1992, MC2010, CEB/FIP1990, AASHTO-LRFD, GL2000, AS3600, JSCE, SAK and B3) prediction models of drying shrinkage have been selected from the standards, codes and researchers. All suggested parameters for the prediction models were considered in the estimation of shrinkage strain for the by-product concretes. In addition, the error percentage and coefficient of variation methods have been used to compute the accuracy of prediction models. The results showed that in early ages, almost all the prediction models estimated similar results with the experimental curves. However, at later ages, only few models for each concrete predicted similar results to the experimental values
Dental age estimation employing CBCT scans enhanced with Mimics software: Comparison of two different approaches using pulp/tooth volumetric analysis
No full textThe methods of dental age estimation and identification of unknown deceased individuals are evolving with the introduction of advanced innovative imaging technologies in forensic investigations. However, assessing small structures like root canal volumes can be challenging in spite of using highly advanced technology. The aim of the study was to investigate which amongst the two methods of volumetric analysis of maxillary central incisors displayed higher strength of correlation between chronological age and pulp/tooth volume ratio for Malaysian adults. Volumetric analysis of pulp cavity/tooth ratio was employed in Method 1 and pulp chamber/crown ratio (up to cemento-enamel junction) was analysed in Method 2. The images were acquired employing CBCT scans and enhanced by manipulating them with the Mimics software. These scans belonged to 56 males and 54 females and their ages ranged from 16 to 65 years. Pearson correlation and regression analysis indicated that both methods used for volumetric measurements had strong correlation between chronological age and pulp/tooth volume ratio. However, Method 2 gave higher coefficient of determination value (R2 = 0.78) when compared to Method 1 (R2 = 0.64). Moreover, manipulation in Method 2 was less time consuming and revealed higher inter-examiner reliability (0.982) as no manual intervention during ‘multiple slice editing phase’ of the software was required. In conclusion, this study showed that volumetric analysis of pulp cavity/tooth ratio is a valuable gender independent technique and the Method 2 regression equation should be recommended for dental age estimation
Mechanical behavior of calcium sulfate scaffold prototypes built by solid free-form fabrication
No full textPurpose: This paper aims to investigate the mechanical behavior of three-dimensional (3D) calcium sulfate porous structures created by a powder-based 3D printer. The effects of the binder-jetting and powder-spreading orientations on the microstructure of the specimens are studied. A micromechanical finite element model is also examined to predict the properties of the porous structures under the load. Design/methodology/approach: The authors printed cylindrical porous and solid samples based on a predefined designed model to study the mechanical behavior of the prototypes. They investigated the effect of three main build bed orientations (x, y and z) on the mechanical behavior of solid and porous specimens fabricated in each direction then evaluated the micromechanical finite-element model for each direction. The strut fractures were analyzed by scanning electron microscopy, micro-computed tomography and the von Mises stress distribution. Findings: Results showed that the orientation of powder spreading and binder jetting substantially influenced the mechanical behavior of the 3D-printed prototypes. The samples that were fabricated parallel to the applied load had higher compressive strength compared with those printed perpendicular to the load. The results of the finite element analysis agreed with the results of the experimental mechanical testing. Research limitations/implications: The mechanical behavior was studied for the material and the 3D-printing machine used in this research. If one were to use another material formulation or machine, the printing parameters would have to be set accordingly. Practical implications: This work aimed to re-tune the control factors of an existing rapid prototyping process for the given machine. The authors achieved these goals without major changes in the already developed hardware and software architecture. Originality/value: The results can be used as guidelines to set the printing parameters and a model to predict the mechanical properties of 3D-printed objects for the development of patient- and site-specific scaffolds
A large free spectral range of 74.92 GHz in comb peaks generated by SU-8 polymer micro-ring resonators: simulation and experiment
No full textThe feasibility of integrated SU-8 polymeric optical waveguides on a silicon platform was demonstrated experimentally and supported by simulation. Micro-ring resonator (MRR) configurations were designed and fabricated using SU-8 polymer. Simulation is carried out using the finite-difference time-domain method to improve the design. Both the simulation and experimental results confirm that SU-8 can be successfully used in the optical MRR. Passive MMI-coupled SU-8 single coupler and double coupler with a free spectral range of 74.92 GHz is achieved practically and corresponds with the simulation result. Moreover, other important parameters such as the full width at half maximum, Q factor and finesse are calculated from the simulation and practical results to support the feasibility of the SU-8 polymer MRR
Currency Order Flow and Exchange Rate Determination: Empirical Evidence from the Malaysian Foreign Exchange Market
No full textThis article presents empirical test results of Malaysian foreign exchange market microstructure assessment of exchange rate dynamics. We apply vector autoregressive (VAR) model to estimate the influential role of currency order flow in the determination of the currency exchange rate for the Malaysian ringgit (MYR) against the US dollar (USD). We investigate whether currency order flow captures the movements of exchange rate of MYR against USD, and how the long-term and short-term components impact the relative estimation of MYR in the international market. We, construct a measure of order flow in the Malaysian foreign exchange market to reflect the pressure of currency excess demand. Our focus is on the cumulative currency order flow and the exchange rate relationship of MYR and USD. A hybrid model of order flow and exchange rate dynamics proposed by Evans and Lyons (2002a) is applied to the Malaysian foreign exchange market (MYR/USD) to analyse a dataset of every 15-minute currency order flow and exchange rate movements from January 2010 to December 2015. Our dataset has unique features in terms of the quality of the data, extensive period and precise high frequency. Our results show that currency order flow explains an important portion of the movements in the MYR–USD exchange rate
Palladium nanoparticle-decorated reduced graphene oxide sheets synthesized using Ficus carica fruit extract: A catalyst for Suzuki cross-coupling reactions
No full textWe present a biogenic method for the synthesis of palladium nanoparticle (PdNP)-modified by reducing graphene oxide sheets (rGO) in a one-pot strategy using Ficus carica fruit juice as the reducing agent. The synthesized material was well characterized by morphological and structural analyses, including, Ultraviolet-Visible spectroscopy (UV-Vis), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and Transmission Electron Microscopy (TEM) and Raman spectroscopy. The results revealed that the PdNP modified GO are spherical in shape and estimated to be a dimension of ~0.16 nm. The PdNP/graphene exhibits a great catalytic activity in Suzuki cross-coupling reactions for the synthesis of biaryl compounds with various substrates under both aqueous and aerobic conditions. The catalyst can be recovered easily and is suitable for repeated use because it retains its original catalytic activity. The PdNP/rGO catalyst synthesized by an eco-friendly protocol was used for the Suzuki coupling reactions. The method offers a mild and effective substitute to the existing methods and may significantly contribute to green chemistry
Panel of serum protein biomarkers to grade the severity of traumatic brain injury
No full textThe Glasgow Coma Scale (GCS), which classifies patients into mild, moderate or severe traumatic brain injury (TBI), is a system used to prioritize treatment and prognosticate the severity of head injury. In this study, sera of patients with various stages of TBI, as well as control subjects, were analyzed to screen for proteins that may be used to complement the GCS system. By subjecting pooled serum samples to iTRAQ analysis for quantitative comparison of protein abundance, and attesting their altered levels using ELISA, we have detected increased levels of serum amyloid A, C-reactive protein, leucine-rich alpha-2-glycoprotein, lipopolysaccharide-binding protein, fibronectin, vitronectin and alpha-1-antichymotrypsin in patients across all strata of TBI relative to the controls. However, kininogen was decreased only in moderate and severe TBI, whereas apolipoprotein E and zinc-alpha-2-glycoprotein were only increased in severe TBI. Hence, we propose a panel of serum biomarkers, which if analyzed within 24 h of the injury, can be used to diagnose patients with TBI into mild, moderate or severe stratification objectively, thus complementing the traditional GCS
Investigating the Tribological Characteristics of Burnished Polyoxymethylene—ANFIS and FE Modeling
No full textPolymers are utilized in numerous tribological applications because of their excellent characteristics; for example, accommodating shock loading and shaft misalignment. A high surface finish is required to ensure consistently good performance and extended service life of manufactured polymeric components. Burnishing is the best choice as a finishing process for this study due to its ability to increase hardness, fatigue strength, and wear resistance and also introduce compressive residual stress on the burnished workpiece. Due to the complexity and uncertainty of the machining processes, soft computing techniques are preferred for anticipating the performance of the machining processes. In this study, ANFIS as an adaptive neuro-fuzzy inference system was applied to anticipate the workpiece hardness and surface roughness after the roller burnishing process. Five burnishing variables, including burnishing depth, feed rate, speed, roller width, and lubrication mode, were analyzed. A Gauss membership function was used for the training process in this study. The predicted surface roughness and hardness data were compared with experimental results and indicated that the Gauss membership function in ANFIS has satisfying accuracy as high as 97% for surface roughness and 96% for hardness. Furthermore, the generated compressive residual stress on the burnished surface was studied by a 2D finite element model (FEM). The simulated results of residual stress were validated with the experimental results obtained from X-ray diffraction (XRD) tests