scholarly journals Design and Fabrication of a New MHD Micropump for Continuous Subcutaneous Infusion to Thalassemia Major Patients

2021 ◽  
Vol In Press (In Press) ◽  
Author(s):  
Babak Zahed ◽  
Amin Behzadmehr ◽  
Ghasem Miri-Aliabad ◽  
Tahereh Fanaei Sheikholeslami ◽  
Hassan Azarkish
Keyword(s):  
Thalassemia Major ◽  
Operating Voltage ◽  
Infusion Pumps ◽  
Bubble Generation ◽  
Subcutaneous Infusion ◽  
Precise Control ◽  
Drug Effectiveness ◽  
Final Design ◽  
Present Design ◽  
Drug Solution

Background: In recent decades, reducing the size of the drug delivery systems along with precise control of the amount of drug pumped, has attracted the attention of many researchers. Objectives: The slow subcutaneous infusion of the deferoxamine in thalassemia major patients during day is of vital importance either for the drug effectiveness. However, this is difficult to achieve due to the large size of the conventional infusion pumps and their high weight. Therefore, size and weight reduction of the infusion pumps are very important issues that must be well addressed. Methods: A biomedical micropump for drug solution infusion to human body based on the magnetohydrodynamic (MHD) concept is and designed, and its performance experimentally is investigated in this research. The key challenge in the fabrication of the micropump is its size, weight, bubble generation, and high operating voltage. Results: The present design is well responded to these problems. The final design operates with a 1.2 v without any bubble generation, while its size and weight are 20 × 40 × 50 mm3 and 90 grams, respectively. The size of the micropump is about 1/3 size of conventional micropump, while its weight is half of them. Conclusions: Therefore, the newly designed micropump has the ability to inject the drug solution to thalassemia major patients with a sufficient infusion rate during the day without disturbing them, so it can increase their quality of life and increase their life expectancy.

scholarly journals Shrinking microbubbles with microfluidics: mathematical modelling to control microbubble sizes

2021 ◽  
Author(s):  
A. Salari ◽  
V. Gnyawali ◽  
I. M. Griffiths ◽  
R. Karshafian ◽  
Michael C. Kolios ◽  
...  
Keyword(s):  
Life Sciences ◽  
Microfluidic Channel ◽  
Flow Focusing ◽  
Bubble Generation ◽  
Microfluidic Platform ◽  
Interfacial Tensions ◽  
Precise Control ◽  
Ultrasound Diagnostics ◽  
Bubble Sizes ◽  
Good Agreement

Microbubbles have applications in industry and life-sciences. In medicine, small encapsulated bubbles (< 10 μm) are desirable because of their utility in drug/oxygen delivery, sonoporation, and ultrasound diagnostics. While there are various techniques for generating microbubbles, microfluidic methods are distinguished due to their precise control and ease-offabrication. Nevertheless, sub-10 μm diameter bubble generation using microfluidics remains challenging, and typically requires expensive equipment and cumbersome setups. Recently, our group reported a microfluidic platform that shrinks microbubbles to sub-10 μm diameters. The microfluidic platform utilizes a simple microbubble-generating flow-focusing geometry, integrated with a vacuum shrinkage system, to achieve microbubble sizes that are desirable in medicine, and pave the way to eventual clinical uptake of microfluidically generated microbubbles. A theoretical framework is now needed to relate the size of the microbubbles produced and the system’s input parameters. In this manuscript, we characterize microbubbles made with various lipid concentrations flowing in solutions that have different interfacial tensions, and monitor the changes in bubble size along the microfluidic channel under various vacuum pressures. We use the physics governing the shrinkage mechanism to develop a mathematical model that predicts the resulting bubble sizes and elucidates the dominant parameters controlling bubble sizes. The model shows a good agreement with the experimental data, predicting the resulting microbubble sizes under different experimental input conditions. We anticipate that the model will find utility in enabling users of the microfluidic platform to engineer bubbles of specific sizes.

Phlebotomy and Bolus Subcutaneous Deferoxamine in Algerian Patients with Thalassemia Major or Intermedia or Sickle Cell Disease Treated with Hydroxyurea.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 3812-3812
Author(s):  
Mohamed Bradai ◽  
Dora Bachir ◽  
Mariane De Montalembert
Keyword(s):  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Combined Therapy ◽  
Iron Chelation ◽  
Thalassemia Major ◽  
Beta Thalassemia ◽  
Cell Disease ◽  
Infusion Pumps ◽  
Hydroxyurea Treatment ◽  
Oral Chelators

Abstract Background: Iron chelation with continuous subcutaneous deferoxamine injections is painful and expensive, in particular due to the cost of infusion pumps. Oral chelators are not widely available in Algeria. This prospective study was designed to evaluate the safety and efficacy of bolus subcutaneous deferoxamine (DFO) and phlebotomy in patients with beta-thalassemia major (TM) or intermedia (TI), or sickle cell disease (SCD), treated with hydroxyurea. Methods: 31 patients were enrolled (22 TM, 5 TI, 4 SCD). Mean hydroxyurea dosage was 17 mg/kg/d [15–24]. Phlebotomy was performed when hemoglobin was &gt;8 g/dL and ferritin &gt;1000 ng/ml; 13 patients met these criteria (5 TM, 4 TI, 4 SCD). One TI patient was not compliant; the 12 remaining patients underwent phlebotomy removing 3 to 7 ml/kg, every 2 to 4 weeks as tolerated. Three mild hypotension episodes were noted. Bolus subcutaneous deferoxamine was given to the 25 patients with adequate health insurance. Mean deferoxamine dosage was 30±6 mg/kg/d, in two daily boluses. Skin nodules developed in 6 patients and a subcutaneous abscess in 1 patient. Blood transfusions were given when hemoglobin was &lt;6g/dL. Results: table 1 phlebotomy only DFO only Phlebotomy+DFO N patients 3 TM, 3 TI 17 TM, 2 TI 2 TM, 4 SCD Median age (yrs) 16.5 [7–50] 15 [6–21] 20.5 [15–24] Median F.U. (mos) 27 [12–38] 20 [12–28] 18 [13–23] Median N erythrocyte concentrates transfused during F.U. 0 [0–1] 6 [0–19] 0 Median baseline ferritin (ng/ml) 2800 4130 3760 Median last ferritin (ng/ml) 884 1510 1665 Conclusions: Combination of phlebotomy and bolus subcutaneous deferoxamine very effectively reduced iron overload in patients with TM, TI and SCD. Phlebotomies could be performed in 12 patients thanks to hydroxyurea treatment which had increased their Hb level above 8 g/dL. Such combined therapy can be proposed in countries which can not afford infusion pumps or oral chelators.

scholarly journals Shrinking microbubbles with microfluidics: mathematical modelling to control microbubble sizes

2021 ◽  
Author(s):  
A. Salari ◽  
V. Gnyawali ◽  
I. M. Griffiths ◽  
R. Karshafian ◽  
Michael C. Kolios ◽  
...  
Keyword(s):  
Life Sciences ◽  
Microfluidic Channel ◽  
Flow Focusing ◽  
Bubble Generation ◽  
Microfluidic Platform ◽  
Interfacial Tensions ◽  
Precise Control ◽  
Ultrasound Diagnostics ◽  
Bubble Sizes ◽  
Good Agreement

Microbubbles have applications in industry and life-sciences. In medicine, small encapsulated bubbles (< 10 μm) are desirable because of their utility in drug/oxygen delivery, sonoporation, and ultrasound diagnostics. While there are various techniques for generating microbubbles, microfluidic methods are distinguished due to their precise control and ease-offabrication. Nevertheless, sub-10 μm diameter bubble generation using microfluidics remains challenging, and typically requires expensive equipment and cumbersome setups. Recently, our group reported a microfluidic platform that shrinks microbubbles to sub-10 μm diameters. The microfluidic platform utilizes a simple microbubble-generating flow-focusing geometry, integrated with a vacuum shrinkage system, to achieve microbubble sizes that are desirable in medicine, and pave the way to eventual clinical uptake of microfluidically generated microbubbles. A theoretical framework is now needed to relate the size of the microbubbles produced and the system’s input parameters. In this manuscript, we characterize microbubbles made with various lipid concentrations flowing in solutions that have different interfacial tensions, and monitor the changes in bubble size along the microfluidic channel under various vacuum pressures. We use the physics governing the shrinkage mechanism to develop a mathematical model that predicts the resulting bubble sizes and elucidates the dominant parameters controlling bubble sizes. The model shows a good agreement with the experimental data, predicting the resulting microbubble sizes under different experimental input conditions. We anticipate that the model will find utility in enabling users of the microfluidic platform to engineer bubbles of specific sizes.

Modeling and Experimental Investigation of Jet Electrolytic Drilling

2010 ◽  
Vol 458 ◽  
pp. 277-282 ◽  
Author(s):  
Hua Zhang ◽  
Jia Wen Xu ◽  
Jian She Zhao
Keyword(s):  
Parameters Optimization ◽  
Experimental Result ◽  
Hole Drilling ◽  
Operating Voltage ◽  
Drilling Process ◽  
Workpiece Material ◽  
Precise Control ◽  
Steel Sheets ◽  
Micro Holes ◽  
Micro Hole

Jet Electrolytic Drilling (JED) is a micro-hole drilling process, which employs a jet of electrolyte for anodic dissolution of workpiece material and does not require entry of a nozzle into the machined hole. JED has been used for drilling small holes in aerospace, electronic, and micro-mechanics. One of the most significant problems on JED is the precise control and parameters optimization of the process. This paper established a two-dimension mathematical model for JED to describe the shape of the drilled hole. The model was validated by comparison of simulation and experimental result. JED experiments were performed on 0.6mm thickness stainless steel sheets with different parameters including nozzle diameter and operating voltage. It is found that JED is suitable for drilling micro-holes with diameter less than 1mm and the operating voltage should better be more than 120V.

Combined Chelation Therapy with Daily Oral Deferiprone and Twice-Weekly Subcutaneous Infusion of Desferrioxamine in Children with β-Thalassemia: 3-Year Experience

2014 ◽  
Vol 133 (2) ◽  
pp. 226-236 ◽  
Author(s):  
Duantida Songdej ◽  
Nongnuch Sirachainan ◽  
Pakawan Wongwerawattanakoon ◽  
Werasak Sasanakul ◽  
Praguywan Kadegasem ◽  
...  
Keyword(s):  
Combined Treatment ◽  
Elevated Serum ◽  
Thalassemia Major ◽  
Hemoglobin E ◽  
Subcutaneous Infusion ◽  
Gastrointestinal Discomfort ◽  
Group 3 ◽  
Group 2 ◽  
Group 1

Objective: To study the efficacy of combined treatment with oral and subcutaneous iron chelators. Material and Methods: 50-100 mg/kg/day of oral deferiprone (DFP) combined with 40 mg/kg/dose s.c. desferrioxamine (DFO) twice weekly were given to transfusion-dependent β-thalassemia children. Results: Enrolled patients (9 with β-thalassemia major and 33 with β-thalassemia hemoglobin E), ranging from 3 to 18 years in age, were divided into 3 groups; group 1 ferritin ≥1,000-2,500 ng/ml (n = 10), group 2 ferritin >2,500-4,000 ng/ml (n = 23) and group 3 ferritin >4,000 ng/ml (n = 9). Of the 42 patients, 28 reached the 36-month follow-up. Ten patients whose ferritin declined <15% while receiving 100 mg/kg/day of DFP were considered nonresponders. The median age and previous transfusion duration before enrollment were significantly higher in nonresponders than responders (p = 0.04 and 0.003, respectively). The responders exhibited a significant fall in median ferritin levels from 2,954.6 to 936.6 ng/ml (p < 0.001). Time to a significant decrease in serum ferritin among responders was 6 months. In 13 patients, 16 episodes of adverse events occurred: hemophagocytosis with cytopenia (n = 1), neutropenia (n = 2), thrombocytopenia (n = 2), elevated alanine aminotransferase (n = 5), elevated serum creatinine (n = 1), proteinuria (n = 1) and gastrointestinal discomfort (n = 4). Conclusion: Combination therapy with daily oral DFP and subcutaneous DFO twice weekly is a safe and effective alternative to chelation monotherapy in β-thalassemia children. © 2014 S. Karger AG, Basel

Toward High-Resolution Low-Voltage SEM

1988 ◽  
Vol 46 ◽  
pp. 218-219
Author(s):  
Zhifeng Shao
Keyword(s):  
Low Voltage ◽  
Spherical Aberration ◽  
Chromatic Aberration ◽  
Limiting Factor ◽  
Operating Voltage ◽  
Probe Radius ◽  
Non Local ◽  
Electron Microscopes ◽  
Image Position ◽  
Scanning Electron Microscopes

Recently, low voltage (≤5kV) scanning electron microscopes have become popular because of their unprecedented advantages, such as minimized charging effects and smaller specimen damage, etc. Perhaps the most important advantage of LVSEM is that they may be able to provide ultrahigh resolution since the interaction volume decreases when electron energy is reduced. It is obvious that no matter how low the operating voltage is, the resolution is always poorer than the probe radius. To achieve 10Å resolution at 5kV (including non-local effects), we would require a probe radius of 5∽6 Å. At low voltages, we can no longer ignore the effects of chromatic aberration because of the increased ratio δV/V. The 3rd order spherical aberration is another major limiting factor. The optimized aperture should be calculated as

A Novel Reconstitution Method for Inducing the Formation of Regular 2-Dimensional Arrays of Membrane Proteins and Lipids

1988 ◽  
Vol 46 ◽  
pp. 152-153 ◽  
Author(s):  
A. Engel ◽  
A. Holzenburg ◽  
K. Stauffer ◽  
J. Rosenbusch ◽  
U. Aebi
Keyword(s):  
Membrane Proteins ◽  
Flow Rate ◽  
Lipid Membranes ◽  
Functional Characterization ◽  
Dimensional Structure ◽  
Electron Crystallography ◽  
Peltier Element ◽  
Protein Ratio ◽  
Precise Control ◽  
3 Dimensional

Reconstitution of solubilized and purified membrane proteins in the presence of phospholipids into vesicles allows their functions to be studied by simple bulk measurements (e.g. diffusion of differently sized solutes) or by conductance measurements after transformation into planar membranes. On the other hand, reconstitution into regular protein-lipid arrays, usually forming at a specific lipid-to-protein ratio, provides the basis for determining the 3-dimensional structure of membrane proteins employing the tools of electron crystallography.To refine reconstitution conditions for reproducibly inducing formation of large and highly ordered protein-lipid membranes that are suitable for both electron crystallography and patch clamping experiments aimed at their functional characterization, we built a flow-dialysis device that allows precise control of temperature and flow-rate (Fig. 1). The flow rate is generated by a peristaltic pump and can be adjusted from 1 to 500 ml/h. The dialysis buffer is brought to a preselected temperature during its travel through a meandering path before it enters the dialysis reservoir. A Z-80 based computer controls a Peltier element allowing the temperature profile to be programmed as function of time.

Multiple-fracturing and viewing of the same frozen sample at different depths using a low temperature FESEM

1996 ◽  
Vol 54 ◽  
pp. 820-821
Author(s):  
M.V. Parthasarathy ◽  
C. Daugherty
Keyword(s):  
Temperature Field ◽  
Low Temperature ◽  
Field Emission ◽  
Multiple Fracture ◽  
Precise Control ◽  
Cold Stage ◽  
Different Depths ◽  
Transfer Device

The versatility of Low Temperature Field Emission SEM (LTFESEM) for viewing frozen-hydrated biological specimens, and the high resolutions that can be obtained with such instruments have been well documented. Studies done with LTFESEM have been usually limited to the viewing of small organisms, organs, cells, and organelles, or viewing such specimens after fracturing them.We use a Hitachi 4500 FESEM equipped with a recently developed BAL-TEC SCE 020 cryopreparation/transfer device for our LTFESEM studies. The SCE 020 is similar in design to the older SCU 020 except that instead of having a dedicated stage, the SCE 020 has a detachable cold stage that mounts on to the FESEM stage when needed. Since the SCE 020 has a precisely controlled lock manipulator for transferring the specimen table from the cryopreparation chamber to the cold stage in the FESEM, and also has a motor driven microtome for precise control of specimen fracture, we have explored the feasibility of using the LTFESEM for multiple-fracture studies of the same sample.

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