Tapered microfluidic device for multi-particle separation based on sedimentation principle

This thesis presents a label-free tapered microfluidic device for a passive multi-particle separation. Separation process plays a significant role in various industries for example, biomedical diagnostic, food processing and substance purification. The growing needs for continuous separation process lead to the creation of numerous microfluidic based separation devices. Currently, microfluidic based separation devices are associated with limitations in terms of design complexity, sample purity and separation throughput. Therefore, a simple novel passive tapered microfluidic separation device with various taper angles (6°, 12°, 20° and 25°) is proposed for high purity separation of biological and non-biological samples. The device utilizes coupling mechanism between hydrodynamic separations along with sedimentation effect for enhancement of sample purity. Computer-aided design software was employed during design stage while Finite Element Analysis (FEA) software was used for device design’s optimization. The device was fabricated using a soft lithography technique and was characterized in terms of physical dimensions and leakage conditions. Size based separation simulations using FEA were carried out for 3 μm and 10 μm diameters polystyrene (PS) microbeads samples as well as a mixture of 3 μm PS microbeads and Human Cervical Epithelial Carcinoma (HeLa) cells. Through FEA simulations, larger particles were collected at Outlet 1 and small particles were collected at Outlet 2 using 20° and 25° tapered devices. Furthermore, experimental tests were conducted with similar settings and samples as in the simulations. Successful multi-particle separations were observed using 20° and 25° tapered devices at 0.5 to 3.0 μl/min flow rates. These results were in agreement with simulation results obtained. Highest purity of 98% was achieved for both samples with the use of 3.0 μl/min flow rate. As a conclusion, a passive tapered microfluidic device capable of multi-particle separation at high sample purity was developed

Feature extraction of speech signal and heartbeat detection in angry emotion identification

Angry is one of emotions that play an essential role in decision making, perception, learning and more. This paper detects the angry emotion by analyzing and recognizing angry speech signal as well as detecting the heartbeat condition. The speech database was uttered by various speakers in different gender and emotions. For the analyzing experiment, several digital signal processing methods such as autocorrelation and linear predication technique was introduced to analyze the features. Then, Artificial Neural Network (ANN) was used to classify each parameter features such as mean fundamental frequency, maximum fundamental frequency, standard deviation fundamental frequency, mean amplitude, pause length ratio and first formant frequency to recognize the emotion. Meanwhile, a heartbeat monitoring circuit was developed to measure the heartbeat. The accuracy of the result has achieved over than 80 percent during emotional recognition test. This method can be used further to recognize angry emotion of patient during counseling session

Nypa Frutican Rachis as building envelope heat insulator

This research is conducted to investigate the possibility of cellulose in Nypa Frutican Rachis to achieve thermal comfort. As Malaysia was known as tropical country which has hot and humid climate, this research focus on to study the transfer of heat through Nypa Frutican Rachis as a roof. Since only Nypa leaves have been used as a roof and have been applied until now in East Malaysia, this project uses an innovation of Nypa palm by using its rachis that contain chemical material that have lower thermal conductivity value such as cellulose and lignin as a roof or building envelope heat insulator. This paper described the experimental study method by measuring the temperature of outer and inner surface of Nypa Frutican Rachis on small physical model study. The temperature was measured by using Digital Infrared Thermometer. The average outer and inner tempe rature for five consecutive days was obtained from the experiment is highlighted. Results show that the average of heat loss and heat transfer conduction for five consecutive days are 9.63 W/h and 9.86 W. This experiment shows a good result and proved that Nypa Frutican Rachis is suitable and effective to be a building envelope heat insulator

A TWO COMPONENT RED BLOOD CELL MODEL FOR SINGLE CELL MECHANIC

ABSTRACT This work presents the deformation of red blood cell (RBC) as it travels in a microchannel using a theoretical model. The developed model predicts the deformation experienced by the RBC when exposed to shear stresses (fluid) as a function of mechanical properties. RBC is known to be a biconcave disk and is modeled as a liquid enclosed with a solid membrane. Therefore it is appropriate to model the RBC as a two component models consists of membrane and cytoplasm. The membrane, assumed to behave as a nearly incompressible material shows hyperelastic response to bending and shearing while the cytoplasm exhibits homogeneous Newtonian fluid properties. The model parameters were determined from the experimental measurements and comparison was made. Agreement in terms of hyperelasticity, deformation rate and stress distribution were found with previous researches

Trends in characterizing single cell's stiffness properties

Biophysical properties of living cells such as mechanical and chemical have been proven to play important roles in regulations of various biological activities including disease progression both at the cellular and molecular levels. In the past decades, a number of research tools have been developed to provide better understanding towards cell¿s biophysical states. This growing interest was supported by the emergence of researches focusing on single cell analysis (SCA) which serves as a platform enabling various experimentation works to be carried out. In this context, various techniques have been developed for single cell¿s mechanical characterization to improve robustness, accuracy and operational flexibility. The generic solution varies from traditional approach, microelectromechanical system (MEMS) and microfluidic. This paper presents a review of progress and developments in the field of single cell mechanical properties specifically discussing on stiffness characterizations. An analytical comparison of the reviewed solutions is presented, and the advantages and disadvantages of different techniques are compared

Biomechanical analysis of posterior lumbar interbody aages

A popular yet effective surgical treatment used in medical field to treat degenerative disc disease related to low back pain is known as the lumbar interbody fusion procedure. One of the main aims of posterior lumbar interbody fusion (PLIF), using cages or bone grafts are to provide stability during body movements and mechanical support between two vertebrae, maintain disc height and to help out with the fusion process. This procedure restores disc height, enlarges the stenotic foramen, stabilises the spine, and provides mechanical strength between vertebrae

An Overview of Electrical Characterization Techniques for Biological Cell

In this paper, various electrical characterization techniques available for biological cell have been systematically reviewed. It covers both invasive and non-invasive approaches for population and single cell based studies. Examples of invasive technique consist of probing and patch clamp that measures the ionic current. However, depending on the applications, the non-invasive techniques are far more superior and popular. Some of the technique such as dielectric spectroscopy, electrorotation and dielectrophoresis measures the cell conductivity and dielectric constant. Furthermore, previous researchers proved that non-invasive technique may reduce the harmful effect on the cell due to electrical exposure. The review compares in terms of working principles, sample applications, advantages and limitations of each technique.&nbsp

Biomechanical evaluation of two different types of interbody cages in posterior lumbar interbody fusion

Posterior lumbar interbody fusion (PLIF) related complications such as cage instability, cage subsidence and pedicle screws loosening are among the most prevalent cases reported postoperatively. These conditions are highly related to mechanical factors (PLIF design and material), patient health condition as well as activities conducted by the patient after undergone the surgery. Latest advancement on PLIF technology has created a new technique that allows the application of unilateral cage insertion in an oblique orientation. This solution has potentially overcome the problem related to an unintended mechanical and clinical shortcoming, provided that a bilateral posterior instrumentation (PI) is instrumented to the construct and the cage is fabricated from a material that is closely imitate the modulus elasticity of the cortical bone. In order to prove these statements, an image based finite element analysis (FEA) was conducted to assess the phenomena of cage subsidence and screw loosening by examining the stress profile on the cage construct and the vertebral bodies. Obliquely-placed unilateral PLIF with PI showed the most promising results. It showed the most minimal stress distortion at cage-endplate and pedicle screw-bone interface. In conclusion, the selection of a biocompatible cage material is the most crucial factors that has to be considered in achieving biomechanical superiority in PLIF surgery

Global Retinoblastoma Presentation and Analysis by National Income Level.

Importance: Early diagnosis of retinoblastoma, the most common intraocular cancer, can save both a child's life and vision. However, anecdotal evidence suggests that many children across the world are diagnosed late. To our knowledge, the clinical presentation of retinoblastoma has never been assessed on a global scale. Objectives: To report the retinoblastoma stage at diagnosis in patients across the world during a single year, to investigate associations between clinical variables and national income level, and to investigate risk factors for advanced disease at diagnosis. Design, Setting, and Participants: A total of 278 retinoblastoma treatment centers were recruited from June 2017 through December 2018 to participate in a cross-sectional analysis of treatment-naive patients with retinoblastoma who were diagnosed in 2017. Main Outcomes and Measures: Age at presentation, proportion of familial history of retinoblastoma, and tumor stage and metastasis. Results: The cohort included 4351 new patients from 153 countries; the median age at diagnosis was 30.5 (interquartile range, 18.3-45.9) months, and 1976 patients (45.4%) were female. Most patients (n = 3685 [84.7%]) were from low- and middle-income countries (LMICs). Globally, the most common indication for referral was leukocoria (n = 2638 [62.8%]), followed by strabismus (n = 429 [10.2%]) and proptosis (n = 309 [7.4%]). Patients from high-income countries (HICs) were diagnosed at a median age of 14.1 months, with 656 of 666 (98.5%) patients having intraocular retinoblastoma and 2 (0.3%) having metastasis. Patients from low-income countries were diagnosed at a median age of 30.5 months, with 256 of 521 (49.1%) having extraocular retinoblastoma and 94 of 498 (18.9%) having metastasis. Lower national income level was associated with older presentation age, higher proportion of locally advanced disease and distant metastasis, and smaller proportion of familial history of retinoblastoma. Advanced disease at diagnosis was more common in LMICs even after adjusting for age (odds ratio for low-income countries vs upper-middle-income countries and HICs, 17.92 [95% CI, 12.94-24.80], and for lower-middle-income countries vs upper-middle-income countries and HICs, 5.74 [95% CI, 4.30-7.68]). Conclusions and Relevance: This study is estimated to have included more than half of all new retinoblastoma cases worldwide in 2017. Children from LMICs, where the main global retinoblastoma burden lies, presented at an older age with more advanced disease and demonstrated a smaller proportion of familial history of retinoblastoma, likely because many do not reach a childbearing age. Given that retinoblastoma is curable, these data are concerning and mandate intervention at national and international levels. Further studies are needed to investigate factors, other than age at presentation, that may be associated with advanced disease in LMICs

The global retinoblastoma outcome study : a prospective, cluster-based analysis of 4064 patients from 149 countries

DATA SHARING : The study data will become available online once all analyses are complete.BACKGROUND : Retinoblastoma is the most common intraocular cancer worldwide. There is some evidence to suggest that major differences exist in treatment outcomes for children with retinoblastoma from different regions, but these differences have not been assessed on a global scale. We aimed to report 3-year outcomes for children with retinoblastoma globally and to investigate factors associated with survival. METHODS : We did a prospective cluster-based analysis of treatment-naive patients with retinoblastoma who were diagnosed between Jan 1, 2017, and Dec 31, 2017, then treated and followed up for 3 years. Patients were recruited from 260 specialised treatment centres worldwide. Data were obtained from participating centres on primary and additional treatments, duration of follow-up, metastasis, eye globe salvage, and survival outcome. We analysed time to death and time to enucleation with Cox regression models. FINDINGS : The cohort included 4064 children from 149 countries. The median age at diagnosis was 23·2 months (IQR 11·0–36·5). Extraocular tumour spread (cT4 of the cTNMH classification) at diagnosis was reported in five (0·8%) of 636 children from high-income countries, 55 (5·4%) of 1027 children from upper-middle-income countries, 342 (19·7%) of 1738 children from lower-middle-income countries, and 196 (42·9%) of 457 children from low-income countries. Enucleation surgery was available for all children and intravenous chemotherapy was available for 4014 (98·8%) of 4064 children. The 3-year survival rate was 99·5% (95% CI 98·8–100·0) for children from high-income countries, 91·2% (89·5–93·0) for children from upper-middle-income countries, 80·3% (78·3–82·3) for children from lower-middle-income countries, and 57·3% (52·1-63·0) for children from low-income countries. On analysis, independent factors for worse survival were residence in low-income countries compared to high-income countries (hazard ratio 16·67; 95% CI 4·76–50·00), cT4 advanced tumour compared to cT1 (8·98; 4·44–18·18), and older age at diagnosis in children up to 3 years (1·38 per year; 1·23–1·56). For children aged 3–7 years, the mortality risk decreased slightly (p=0·0104 for the change in slope). INTERPRETATION : This study, estimated to include approximately half of all new retinoblastoma cases worldwide in 2017, shows profound inequity in survival of children depending on the national income level of their country of residence. In high-income countries, death from retinoblastoma is rare, whereas in low-income countries estimated 3-year survival is just over 50%. Although essential treatments are available in nearly all countries, early diagnosis and treatment in low-income countries are key to improving survival outcomes.The Queen Elizabeth Diamond Jubilee Trust and the Wellcome Trust.https://www.thelancet.com/journals/langlo/homeam2023Paediatrics and Child Healt