Near-infrared free carrier absorption in heavily doped silicon

Free carrier absorption in heavily doped silicon can have a significant impact on devices operating in the infrared. In the near infrared, the free carrier absorption process can compete with band to band absorption processes, thereby reducing the number of available photons to optoelectronic devices such as solar cells. In this work, we fabricate 18 heavily doped regions by phosphorus and boron diffusion into planar polished silicon wafers; the simple sample structure facilitates accurate and precise measurement of the free carrier absorptance. We measure and model reflectance and transmittance dispersion to arrive at a parameterisation for the free carrier absorption coefficient that applies in the wavelength range between 1000 and 1500 nm, and the range of dopant densities between ∼10¹⁸ and 3 × 10²⁰ cm⁻³. Our measurements indicate that previously published parameterisations underestimate the free carrier absorptance in phosphorus diffusions. On the other hand, published parameterisations are generally consistent with our measurements and model for boron diffusions. Our new model is the first to be assigned uncertainty and is well-suited to routine device analysis

Skin ulceration as a complication from unexpected extravasation injury: A case report

Extravasation injury (EVI) is common, yet it is always underestimated and underreported. Severity varies ranging from thrombophlebitis up to disability. Unrecognised EVI is a potential medicolegal case in medicine. We experience a 47-year-old lady who developed an unrecognised EVI after being admitted for sepsis. The EVI turned out to be a huge and sloughy skin ulcer. A series of wound debridement with vacuum dressing were conducted until the wound was able to be closed. The EVI can be categorised according to Amjad EVI grading and Loth and Eversmann’s EVI classification. Adult EVI tends to be overlooked, especially during critical care because patients cannot complain upon sedation and ventilation. In order to prevent EVI, firstly prevention is better than cure. Secondly, if EVI is recognised early, infusion should be stopped immediately. Thirdly, analgesia is mandatory. Finally, the plastic team needs to be engaged if it is deemed required. Prevention and early intervention before the occurrence of progressive tissue damage is the key to treatment. Early radical wound debridement and immediate or delayed wound coverage with skin graft or skin flap are indicated in full thickness skin necrosis, persistent pain, and chronic ulcer

Effect of Roof Design Configurations On Natural Ventilation with an Obstacle Inside the Building Model

Roof shape, roof angle, and internal obstacle are some of the factors that have a substantial impact on building's ventilation performance. However, previous roof ventilation studies have not considered the influence of internal obstacle which can affect the overall building’s ventilation performance. For this study, CFD was used to study the effect of roof design configurations on natural ventilation with an obstacle inside the building model. The numerical simulation was carried out by using steady RANS equation specifically the Standard k-ε with enhanced wall treatment. A total of 40 simulation cases were carried out. The study considered two roof shapes mainly the sawtooth roof and the saltbox roof with varying roof angle which were 10º, 20º, 30º, and 40º. Internal obstacles with various height were further added into the simulation cases. Next, grid sensitivity analysis was carried out using Grid Convergence Index (GCI) and Factor of two of observations (FAC2) analysis was carried out as model verification method to ensure a reliable simulation result. Based on the results, it is found that airflow characteristics such as wind speed, distribution of pressure coefficient, and flowrate of an isolated building are strongly dependent on the roof shape and roof angle. Next, the dimensionless flowrate (DFR) is measured to be highest with largest roof angle while lowest with smaller roof angle. Furthermore, the DFR of a building with internal obstacle is lower than that without an internal obstacle due to blockage of incoming air. Moreover, the results show that the sawtooth roof outperforms the saltbox roof in terms of measured parameter. Finally, the study concluded that an isolated building with higher roof angle and without an internal obstacle leads to the best dimensionless flowrate throughout the building.Roof shape, roof angle, and internal obstacle are some of the factors that have a substantial impact on building's ventilation performance. However, previous roof ventilation studies have not considered the influence of internal obstacle which can affect the overall building’s ventilation performance. For this study, CFD was used to study the effect of roof design configurations on natural ventilation with an obstacle inside the building model. The numerical simulation was carried out by using steady RANS equation specifically the Standard k-ε with enhanced wall treatment. A total of 40 simulation cases were carried out. The study considered two roof shapes mainly the sawtooth roof and the saltbox roof with varying roof angle which were 10º, 20º, 30º, and 40º. Internal obstacles with various height were further added into the simulation cases. Next, grid sensitivity analysis was carried out using Grid Convergence Index (GCI) and Factor of two of observations (FAC2) analysis was carried out as model verification method to ensure a reliable simulation result. Based on the results, it is found that airflow characteristics such as wind speed, distribution of pressure coefficient, and flowrate of an isolated building are strongly dependent on the roof shape and roof angle. Next, the dimensionless flowrate (DFR) is measured to be highest with largest roof angle while lowest with smaller roof angle. Furthermore, the DFR of a building with internal obstacle is lower than that without an internal obstacle due to blockage of incoming air. Moreover, the results show that the sawtooth roof outperforms the saltbox roof in terms of measured parameter. Finally, the study concluded that an isolated building with higher roof angle and without an internal obstacle leads to the best dimensionless flowrate throughout the building

Effect of Roof Design Configurations On Natural Ventilation with an Obstacle Inside the Building Model

Roof shape, roof angle, and internal obstacle are some of the factors that have a substantial impact on building's ventilation performance. However, previous roof ventilation studies have not considered the influence of internal obstacle which can affect the overall building’s ventilation performance. For this study, CFD was used to study the effect of roof design configurations on natural ventilation with an obstacle inside the building model. The numerical simulation was carried out by using steady RANS equation specifically the Standard k-ε with enhanced wall treatment. A total of 40 simulation cases were carried out. The study considered two roof shapes mainly the sawtooth roof and the saltbox roof with varying roof angle which were 10º, 20º, 30º, and 40º. Internal obstacles with various height were further added into the simulation cases. Next, grid sensitivity analysis was carried out using Grid Convergence Index (GCI) and Factor of two of observations (FAC2) analysis was carried out as model verification method to ensure a reliable simulation result. Based on the results, it is found that airflow characteristics such as wind speed, distribution of pressure coefficient, and flowrate of an isolated building are strongly dependent on the roof shape and roof angle. Next, the dimensionless flowrate (DFR) is measured to be highest with largest roof angle while lowest with smaller roof angle. Furthermore, the DFR of a building with internal obstacle is lower than that without an internal obstacle due to blockage of incoming air. Moreover, the results show that the sawtooth roof outperforms the saltbox roof in terms of measured parameter. Finally, the study concluded that an isolated building with higher roof angle and without an internal obstacle leads to the best dimensionless flowrate throughout the building.Roof shape, roof angle, and internal obstacle are some of the factors that have a substantial impact on building's ventilation performance. However, previous roof ventilation studies have not considered the influence of internal obstacle which can affect the overall building’s ventilation performance. For this study, CFD was used to study the effect of roof design configurations on natural ventilation with an obstacle inside the building model. The numerical simulation was carried out by using steady RANS equation specifically the Standard k-ε with enhanced wall treatment. A total of 40 simulation cases were carried out. The study considered two roof shapes mainly the sawtooth roof and the saltbox roof with varying roof angle which were 10º, 20º, 30º, and 40º. Internal obstacles with various height were further added into the simulation cases. Next, grid sensitivity analysis was carried out using Grid Convergence Index (GCI) and Factor of two of observations (FAC2) analysis was carried out as model verification method to ensure a reliable simulation result. Based on the results, it is found that airflow characteristics such as wind speed, distribution of pressure coefficient, and flowrate of an isolated building are strongly dependent on the roof shape and roof angle. Next, the dimensionless flowrate (DFR) is measured to be highest with largest roof angle while lowest with smaller roof angle. Furthermore, the DFR of a building with internal obstacle is lower than that without an internal obstacle due to blockage of incoming air. Moreover, the results show that the sawtooth roof outperforms the saltbox roof in terms of measured parameter. Finally, the study concluded that an isolated building with higher roof angle and without an internal obstacle leads to the best dimensionless flowrate throughout the building

Effect of Opening Size on Wind-Driven Cross Ventilation

The opening size on indoor airflow is important to the ventilation of building because various size openings change the ventilation performance for building. Therefore, the objective of this study is to investigate the effect of opening size on indoor airflow characteristics of naturally ventilated building model. The numerical simulation with steady RANS equations was used. A total of six different opening ratios, namely 4:1, 2:1, 1:1, 1:2, 4:9 and 1:4 were considered in this study. The results of mesh independence study and model validation were also in good agreement with previous study. The simulation results show that velocity and pressure of the indoor air, ventilation rate, and pressure coefficient are highly dependent on the opening ratio. The velocity and pressure contour indicate that the lower the opening ratio, the higher the velocity and subsequently lower pressure inside the building. In addition, the pressure coefficient and ventilation rate are also increased as the opening ratio decreases. Besides, the results indicate that percentage increase in ventilation rate of opening ratio 4:1 and 2:1, 2:1 and 1:1, and 1:1 and 1:2 is higher than those of opening ratio for 1:2 and 4:9, 4:9 and 1:4. The study concluded that pairing a large outlet and small inlet leads to increase in better ventilation rate for building

Impact of eave and roof pitch on cross ventilation for an isolated building with sawtooth roof

An eave refers to an extension attached to the building roof to protect the interior space from direct solar radiation and improve the performance on cross ventilation. In this study, the impact of eave inclination angle and roof pitch of an isolated sawtooth roof building on cross ventilation were investigated. The eave configurations at either windward or leeward openings were included. 3D steady Reynolds-Averaged Navier-Stokes (RANS) equation in combination with the Shear-Stress Transport model (SST k-ω model) was used for the Computational Fluid Dynamics (CFD) simulations. Grid sensitivity study was carried out and the performance of cross ventilation was evaluated based on the non-dimensional velocity magnitude, spatial distribution of pressure coefficient as well as the ventilation rate of the building. For the simulation model with 55° roof pitch, it is observed that a region with high velocity magnitude formed on top of the leeward eave due to the higher roof pitch and presence of the leeward eave. Results also indicated that the building model with 90° leeward eave and 55° roof pitch has the highest increment in ventilation rate which is 7.16%. On the other hand, the building model with 90° windward eave has the highest pressure coefficient because more blockage of airflow is caused by a steeper roof as the roof pitch of the building increases. Furthermore, the building model with 90° leeward eave shows a larger region with negative pressure at the leeward façade indicating higher airflow leaving the leeward opening. Therefore, the airflow behavior and characteristic are both dependent on the roof pitch and eave inclination angle for a naturally ventilated building

CD133 marks for colorectal adenocarcinoma

Abstract CD133, a marker which has been advocated to mark colorectal carcinoma "stem or tumour initiating cells" is amongst the frequently studied markers in colorectal cancer. A study was conducted at the Department of Pathology, University of Malaya Medical Centre to determine the expression of CD133 in 56 archived, formalin-fi xed, paraffi n-embedded colorectal adenocarcinoma in comparison with adjacent benign colorectal epithelium by immunohistochemical staining for CD133 expression. CD133 immunopositivity was determined as staining at the glandular luminal surface or in the intraluminal debris. Expression was semiquantitated for (1) proportion of CD133 immunopositivity in the malignant or adjacent benign colorectal epithelium and (2) intensity of staining. The fi nal score of CD133 immunopositivity was arbitrarily taken as proportion of CD133 immunopositivity multiplied by intensity of staining in both the malignant and adjacent benign colorectal epithelium. CD133 expression was observed in signifi cantly increased frequency in 49 (87.5%) colorectal adenocarcinoma compared with 15 (26.8%) of the adjacent benign colorectal epithelium (p<0.05). In terms of immunopositivity score (proportion of CD133 immunopositivity multiplied by intensity of staining), colorectal adenocarcinoma had a mean arbitrary score of 8.5 which was signifi cantly higher than the mean immunopositivity score of 0.5 of the adjacent benign colorectal epithelium (p<0.05). In addition, the maximum immunopositivity score for the adjacent benign colorectal epithelium was 4, while 38 (67.9%) of colorectal adenocarcinoma had scores >4. This study shows that CD133 is able to mark colorectal adenocarcinoma but it is still unclear at this juncture whether CD133 is indeed a marker for colorectal adenocarcinoma "stem cells"

Effects of roof configuration on natural ventilation for an isolated building

Numerical analyses based on CFD steady RANS were conducted to investigate the effects of roof configuration on wind-induced natural ventilation for an isolated roofed building. Gable roof and saltbox roof building models were tested with 15˚, 25˚, 35˚ and 45˚ roof pitch in present study. The flow field information and flow characteristics were obtained from the contours and plots generated by CFD. In accordance to the increment of roof pitch, the turbulence kinetic energy and mean velocity ratio show vigorous response. The flow separated at the windward corner do not reattach onto the roof, thus induced higher velocity gradient and form a large vortex at the roof ridge. The vortices behind then building caused by the flow separation at the roof ridge extend along the mixing layer and spread up to the roof. The pressure differences mainly rely on the roof shapes. Greater pressure differences between the upstream, interior and downstream was observed in saltbox roof cases. This is due to the extended roof height which boosted the impinging effect caused by the incoming wind. Generally, the saltbox roof configuration exhibit better performance than gable roof in terms of the measured parameters