Geospatial Analytics for COVID-19 Active Case Detection

Ever since the COVID-19 pandemic started in Wuhan, China, much research work has been focusing on the clinical aspect of SARS-CoV-2. Researchers have been leveraging on various Artificial Intelligence techniques as an alternative to medical approach in understanding the virus. Limited studies have, however, reported on COVID-19 transmission pattern analysis, and using geography features for prediction of potential outbreak sites. Predicting the next most probable outbreak site is crucial, particularly for optimizing the planning of medical personnel and supply resources. To tackle the challenge, this work proposed distance-based similarity measures to predict the next most probable outbreak site together with its magnitude, when would the outbreak likely to happen and the duration of the outbreak. The work began with preprocessing of 1365 patient records from six districts in the most populated state named Selangor in Malaysia. The dataset was then aggregated with population density information and human elicited geography features that might promote the transmission of COVID-19. Empirical findings indicated that the proposed unified decision-making approach outperformed individual distance metric in predicting the total cases, next outbreak location, and the time interval between start dates of two similar sites. Such findings provided valuable insights for policymakers to perform Active Case Detection.     

Improvement of thermal conductivity and dielectric constant of graphene-filled epoxy nanocomposites using colloidal polymerization approach

Polymer Bulletin - The effect of the polymeric cross-link density on the thermal conductivity of an oxidized graphene (OG)-filled epoxy nanocomposite was investigated by two different fabrication...     

Effect of lubricant on the formation of heavy-duty diesel exhaust nanoparticles

The effect of lubricants on nanoparticle formation in heavy-duty diesel exhaust with and without a continuously regenerating diesel particulate filter (CRDPF) is studied. A partial flow sampling system with a particle size distribution measurement starting from 3 nm, approximately, is used. Tests are conducted using four different lubricant formulations, a very low sulfur content fuel, and four steady-state driving modes. A well-documented test procedure was followed for each test. Two different kinds of nanoparticle formation were observed, and both were found to be affected bythe lubricant but in differentway. Without CRDPF, nanoparticles were observed at low loads. No correlation between lubricant sulfur and these nanoparticles was found. These nanoparticles are suggested to form mainly from hydrocarbons. With CRDPF, installed nanoparticles were formed only at high load. The formation correlated positively with the lubricant (and fuel) sulfur level, suggesting that sulfuric compounds are the main nucleating species in this situation. Storage effects of CRDPF had an effect on nanoparticle concentration as the emissions of nanoparticles decreased over time.     

Hydroelastic piping vibration analysis by transfer matrices

A compact method is presented for determining the simultaneous acoustic and mechanical steady-state vibrations in three-dimensional piping conveying fluid. The method is based on transfer matrices which are applied for proper members of the piping such as straight pipes and bends and equipment including pumps, valves, accumulators, supports and snubbers. In addition to the high accuracy, the method has the advantage that it involves simultaneous solution of no more than 7 algebraic equations. A numerical instability associated with the transverse waves in the pipe constitutes the main drawback and is solved by a linear transformation leading to a diagonalised transfer matrix of a straight pipe. The method is finally extended to transient vibrations by performing a Fourier inversion from the frequency domain into the time domain on the basis of the theorem of residues.The method has been applied to the steady-state vibration of a reciprocating pump suction line and to the response of a cantilevered L-shaped pipe to an instantaneous valve closure at the fixed end. The results are compared with those obtained by ignoring the hydroelastic coupling between the fluid and the pipe.     

Fatigue Life Assessment and Static Testing of Structural GFRP Tubes Based on Coupon Tests

Fiber-reinforced polymer (FRP) hollow tubes are used in structural applications, such as utility poles and pipelines. Concrete-filled FRP tubes (CFFTs) are also used as piles and bridge piers. Applications such as poles and marine piles are typically governed by cyclic bending. In this paper, the fatigue behavior of glass-FRP filament-wound tubes is studied using coupons cut from the tubes. Several coupon configurations were first examined in 24 tension and five compression monotonic loading tests. Fatigue tests were then conducted on 81 coupons to examine several parameters; namely, loading frequency as well as maximum-to-ultimate (σmax/σult) and minimum-to-maximum (σmin/σmax) stress ratios, including tension tension and tension compression, to simulate reversed bending. The study demonstrated the sensitivity of test results and failure mode to coupon configuration. The presence of compression loads reduced fatigue life, while increasing load frequency increased fatigue life. Stiffness degradation behavior was also established. To achieve at least one million cycles, it is recommended to limit (σmax/σult) to 0.25. Models were used to simulate stiffness degradation and fatigue life curve of the tube. Fatigue life predictions of large CFFT beams showed good correlation with experimental results.     

The control of radon progeny by air treatment devices

The effect of air treatment devices on the behaviour of radon decay products has been studied in laboratory conditions. An HEPA filter and an electrostatic precipitator were used. Both of the filters were found to decrease the equilibrium factor of daughters and increase the unattached fraction of decay products. In a clean air they also decreased the activity of unattached daughters. The effect of the devices on the health risk caused by radon progeny was estimated by dosimetric calculations. The results corresponding to different models show considerable discrepancy, mainly due to different assumptions about the influence of unattached decay products on the dose.     

Transfer of surface-dried Listeria monocytogenes from stainless steel knife blades to roast turkey breast

Listeria contamination of food contact surfaces can lead to cross-contamination of ready-to-eat foods in delicatessens. Recognizing that variations in Listeria biofilm-forming ability exist, the goal of this study was to determine whether these differences in biofilm formation would affect the Listeria transfer rate during slicing of delicatessen turkey meat. In this study, six previously identified strong and weak biofilm-forming strains of Listeria monocytogenes were grown at 22 degrees C for 48 h on Trypticase soy agar containing 0.6% yeast extract and harvested in 0.1% peptone. Thereafter, the strains were combined to obtain two 3-strain cocktails, resuspended in turkey slurry, and inoculated onto flame-sterilized AISI grade 304 stainless steel knife blades that were subjected to 6 and 24 h of ambient storage at approximately 78% relative humidity. After mounting on an Instron Universal Testing Machine, these blades were used to obtain 16 slices of retail roast turkey breast. Based on an analysis of the slices by direct plating, Listeria populations decreased 3 to 5 log CFU per slice after 16 slices. Overall, total transfer to turkey was significantly greater for strong (4.4 log CFU total) as opposed to weak (3.5 log CFU total; P < 0.05) biofilm formers. In addition, significantly more cells were transferred at 6 (4.6 log CFU total) than at 24 h (3.3 log CFU total; P < 0.05) with Listeria quantifiable to the 16th slice, regardless of the inoculation level. Increased survival by the strong biofilm formers, as evidenced by viability staining, suggests that these strains are better adapted to survive stressful conditions than their weak biofilm-forming counterparts.     

Virtual Impactor as an Accessory to Optical Particle Counters

A method to improve the sensitivity of optical particle counters for large particles is presented. The basic idea is to increase the concentration in the sample air by connecting a virtual impactor to the sample inlet of an optical particle counter. For particles with D _p > 3 μm, the number concentration is increased by a factor of 20. The improvement in statistical accuracy is particularly useful in Alter testing and clean room measurements. The differences in the size distributions measured with and without the virtual impactor are used in estimating the relationship between the aerodynamic and optical sizes of different aerosols.     

Towards traceable particle number concentration standard: Single charged aerosol reference (SCAR)

A concept of realizing a standard for aerosol particle number concentration was tested, based on generating singly charged aerosol particles in the size range from 10 up to 500 nm. To this end, a device named single-charged aerosol reference (SCAR) was designed, built, and tested. The device is based on electrical charging of nanoparticles and subsequent growth of the particles. With an accurate measurement of volume flow and electrical current from the singly charged particles, the number concentration can be accurately, and in the end, traceably determined. Laboratory tests have shown that the device can be used to generate a narrow (GSD<1.3) particle size distribution of singly charged particles. The device can be used for traceable calibration of instruments measuring the number concentration of the particles.     

Living-related liver transplantation in Africa

Liver transplantation is an effective therapy for end stage liver disease. Nevertheless in many areas of the world organ availability remains a major problem. We report here the success of the first living-related liver transplantation in Africa. The left lateral lobe of the mother was transplanted orthotopically to her 6 year old child suffering from liver cirrhosis complicating glycogen storage disease. The social and medical problems encountered are discussed. Living-related liver transplantation is a viable option in countries where cadaveric organ donation is either illegal or socially unacceptable.