scholarly journals Microfluidic active pressure and flow stabiliser

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Simon Södergren ◽  
Karolina Svensson ◽  
Klas Hjort
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Thermal Control ◽  
Dead Volume ◽  
Glass Chip ◽  
Total Analysis ◽  
The Stability ◽  
Upstream Flow

AbstractIn microfluidics, a well-known challenge is to obtain reproducible results, often constrained by unstable pressures or flow rates. Today, there are existing stabilisers made for low-pressure microfluidics or high-pressure macrofluidics, often consisting of passive membranes, which cannot stabilise long-term fluctuations. In this work, a novel stabilisation method that is able to handle high pressures in microfluidics is presented. It is based on upstream flow capacitance and thermal control of the fluid’s viscosity through a PID controlled restrictor-chip. The stabiliser consists of a high-pressure-resistant microfluidic glass chip with integrated thin films, used for resistive heating. Thereby, the stabiliser has no moving parts. The quality of the stabilisation was evaluated with an ISCO pump, an HPLC pump, and a Harvard pump. The stability was greatly improved for all three pumps, with the ISCO reaching the highest relative precision of 0.035% and the best accuracy of 8.0 ppm. Poor accuracy of a pump was compensated for in the control algorithm, as it otherwise reduced the capacity to stabilise longer times. As the dead volume of the stabiliser was only 16 nL, it can be integrated into micro-total-analysis- or other lab-on-a-chip-systems. By this work, a new approach to improve the control of microfluidic systems has been achieved.

scholarly journals Crystal structures and dynamical properties of dense CO2

2016 ◽  
Vol 113 (40) ◽  
pp. 11110-11115 ◽  
Author(s):  
Xue Yong ◽  
Hanyu Liu ◽  
Min Wu ◽  
Yansun Yao ◽  
John S. Tse ◽  
...  
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Theoretical Calculations ◽  
Ambient Pressure ◽  
Md Simulations ◽  
Ab Initio Molecular Dynamics ◽  
Structural Polymorphism ◽  
Stability Structure ◽  
Dynamical Properties ◽  
The Stability

Structural polymorphism in dense carbon dioxide (CO2) has attracted significant attention in high-pressure physics and chemistry for the past two decades. Here, we have performed high-pressure experiments and first-principles theoretical calculations to investigate the stability, structure, and dynamical properties of dense CO2. We found evidence that CO2-V with the 4-coordinated extended structure can be quenched to ambient pressure below 200 K—the melting temperature of CO2-I. CO2-V is a fully coordinated structure formed from a molecular solid at high pressure and recovered at ambient pressure. Apart from confirming the metastability of CO2-V (I-42d) at ambient pressure at low temperature, results of ab initio molecular dynamics and metadynamics (MD) simulations provided insights into the transformation processes and structural relationship from the molecular to the extended phases. In addition, the simulation also predicted a phase V′(Pna21) in the stability region of CO2-V with a diffraction pattern similar to that previously assigned to the CO2-V (P212121) structure. Both CO2-V and -V′ are predicted to be recoverable and hard with a Vicker hardness of ∼20 GPa. Significantly, MD simulations found that the CO2 in phase IV exhibits large-amplitude bending motions at finite temperatures and high pressures. This finding helps to explain the discrepancy between earlier predicted static structures and experiments. MD simulations clearly indicate temperature effects are critical to understanding the high-pressure behaviors of dense CO2 structures—highlighting the significance of chemical kinetics associated with the transformations.

Phase transitions of BaCO3 at high pressures

2008 ◽  
Vol 72 (2) ◽  
pp. 659-665 ◽  
Author(s):  
S. Ono ◽  
J. P. Brodholt ◽  
G. D. Price
Keyword(s):  
Phase Transition ◽  
Experimental Study ◽  
High Pressure ◽  
Phase Transitions ◽  
Bulk Modulus ◽  
First Principles ◽  
High Pressures ◽  
Ambient Conditions ◽  
The Stability ◽  
Previous Experimental Study

AbstractFirst-principles simulations and high-pressure experiments were used to study the stability of BaCO3 carbonates at high pressures. Witherite, which is orthorhombic and isotypic with CaCO3 aragonite, is stable at ambient conditions. As pressure increases, BaCO3 transforms from witherite to an orthorhombic post-aragonite structure at 8 GPa. The calculated bulk modulus of the post-aragonite structure is 60.7 GPa, which is slightly less than that from experiments. This structure shows an axial anisotropicc ompressibility and the a axis intersects with the c axis at 70 GPa, which implies that the pressure-induced phase transition reported in previous experimental study is misidentified. Although a pyroxene-like structure is stable in Mg- and Ca-carbonates at pressures >100 GPa, our simulations showed that this structure does not appear in BaCO3.

scholarly journals Partial drying of apple fruits to improve freeze/thaw quality during long term frozen storage

2018 ◽  
Author(s):  
S. Bellaga ◽  
L. Ben Haj Said ◽  
K. Allaf
Keyword(s):  
Water Content ◽  
Frozen Storage ◽  
Color Difference ◽  
Total Polyphenol ◽  
Positive Effects ◽  
The Stability ◽  
Quality Assessments ◽  
Apple Fruits

Apple samples were submitted to partially drying prior to freezing. Then, quality assessments were achieved in order to evaluate the quality of these various frozen samples during frozen-storage. Significant positive effects of water content were observed on thaw exudate water and total color difference of dehydrofrozen/thawed apples. Total polyphenol content and total flavonoid content losses were important for samples without any dehydration pretreatment. They noticeably decreased when water content decreased during the whole period of storage. Thus, a partial removal of water prior to freezing is a relevant way to maintain the stability of fruit quality during long-term frozen-storage. Keywords: Apple fruits; dehydrofreezing; frozen storage; color; polyphenol

scholarly journals An investigation of reconstituted terlipressin infusion stability for use in hepatorenal syndrome

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Thi Ngoc Nhieu Bui ◽  
Su Sandar ◽  
Giuseppe Luna ◽  
Jasmine Beaman ◽  
Bruce Sunderland ◽  
...  
Keyword(s):  
Hepatorenal Syndrome ◽  
Colour Change ◽  
First Line ◽  
Term Survival ◽  
Advanced Cirrhosis ◽  
Elimination Half ◽  
Stability Data ◽  
The Stability

AbstractHepatorenal syndrome (HRS) is a fatal complication of renal dysfunction associated with ascites, liver failure and advanced cirrhosis. Although the best option for long-term survival is liver transplantation, in the critical acute phase, vasoconstrictors are considered first-line supportive agents. Terlipressin is the most widely used vasoconstrictor globally but owing to its short elimination half-life, it is usually administered six hourly by slow intravenous bolus injection. This requires patients to remain in hospital, increasing hospital bed costs and affecting their quality of life. An alternative option for administration of terlipressin is as a continuous infusion using an elastomeric infusor device in the patient’s home. However, stability data on terlipressin in elastomeric infusor devices is lacking. This research aimed to evaluate the stability of terlipressin reconstituted in infusor devices for up to 7 days at 2–8 °C and subsequently at 22.5 °C for 24 h, to mimic home storage and administration temperatures. We report that terlipressin was physically and chemically stable under these conditions; all reconstituted infusor concentrations retained above 90% of the original concentration over the test conditions. No colour change or precipitation in the solutions were evident.

Digital currencies and digital transformation strategy

2021 ◽  
Vol 23 (1) ◽  
pp. 13-18
Author(s):  
ILYA EMELIN ◽  
Keyword(s):  
Structural Changes ◽  
Well Being ◽  
Digital Transformation ◽  
Business Partnerships ◽  
Negative Consequences ◽  
Digital Service ◽  
Complicated Process ◽  
The Stability

The paper examines the events of the Gaidar Forum – 2021 dedicated to the features of digital transformation. By analyzing the speakers’ presentations, the author notes the need to minimize the negative consequences of the coronavirus pandemic for the world economy, to unleash the creative potential and sustainable development of countries. At the same time, the question of creating an image of the future, a semantic paradigm, a strategy for the development of an integral system remains relevant. This requires strengthening business partnerships, well-coordinated interaction of government agencies (departmental and interdepartmental), and improvement of the digital economy during its transformation. The digitalization of economy enhances economic growth, creates opportunities for structural transformations, and necessary conditions for the “post-covid” development of the healthcare system. Digitalization should bring about a proactive, standardized online public service delivery. Digital transformation brings many significant structural changes affecting many areas of our lives. Since digitalization is a long-term and complicated process, particular attention should be paid to maintaining the stability of the labor market, the efficiency of the education system, and the security of big data. Digital transformation should improve the quality of public services, the overall number of digital service users, and the growth of citizens’ well-being

Electronic Properties of Magnetic Superconductor HoNi2B2C Under High Pressure

2003 ◽  
Vol 17 (18n20) ◽  
pp. 3664-3671 ◽  
Author(s):  
G. Oomi ◽  
N. Matsuda ◽  
T. Kagayama ◽  
C. K. Cho ◽  
P. C. Canfield
Keyword(s):  
Magnetic Field ◽  
High Pressure ◽  
Electrical Resistivity ◽  
Fermi Liquid ◽  
High Pressures ◽  
Metamagnetic Transition ◽  
Liquid Behavior ◽  
The Stability ◽  
Normal Fermi ◽  
Fermi Liquid Behavior

The electrical resistivity of single crystalline HoNi 2 B 2 C has been measured at high pressure and magnetic fields. The three anomalies in the magnetoresistance due to metamagnetic transitions are observed both at ambient and high pressures. It is found that the metamagnetic transition fields increase with increasing pressure. The temperature dependence of electrical resistivity is strongly dependent on magnetic field. Non Fermi liquid behavior is observed near the metamagnetic transition fields. But the normal Fermi liquid behavior recovers after completing the phase transition. The Grüneisen parameters are also calculated to examine the stability of electronic state.

scholarly journals Strong hydrogen bonding in a dense hydrous magnesium silicate discovered by neutron Laue diffraction

IUCrJ ◽  
2020 ◽  
Vol 7 (3) ◽  
pp. 370-374
Author(s):  
Narangoo Purevjav ◽  
Takuo Okuchi ◽  
Christina Hoffmann
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Cation Exchange ◽  
High Pressures ◽  
Magnesium Silicate ◽  
Weight Fraction ◽  
Laue Diffraction ◽  
Hydrogen Capacity ◽  
Temperature Conditions

A large amount of hydrogen circulates inside the Earth, which affects the long-term evolution of the planet. The majority of this hydrogen is stored in deep Earth within the crystal structures of dense minerals that are thermodynamically stable at high pressures and temperatures. To understand the reason for their stability under such extreme conditions, the chemical bonding geometry and cation exchange mechanism for including hydrogen were analyzed in a representative structure of such minerals (i.e. phase E of dense hydrous magnesium silicate) by using time-of-flight single-crystal neutron Laue diffraction. Phase E has a layered structure belonging to the space group R 3 m and a very large hydrogen capacity (up to 18% H2O weight fraction). It is stable at pressures of 13–18 GPa and temperatures of up to at least 1573 K. Deuterated high-quality crystals with the chemical formula Mg2.28Si1.32D2.15O6 were synthesized under the relevant high-pressure and high-temperature conditions. The nuclear density distribution obtained by neutron diffraction indicated that the O—D dipoles were directed towards neighboring O2− ions to form strong interlayer hydrogen bonds. This bonding plays a crucial role in stabilizing hydrogen within the mineral structure under such high-pressure and high-temperature conditions. It is considered that cation exchange occurs among Mg2+, D+ and Si4+ within this structure, making the hydrogen capacity flexible.

scholarly journals Antifungal Soybean Protein Concentrate Adhesive as Binder of Rice Husk Particleboards

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3540
Author(s):  
Andrés Larregle ◽  
Mayra Chalapud ◽  
Florencia Fangio ◽  
Emiliano M. Ciannamea ◽  
Pablo M. Stefani ◽  
...  
Keyword(s):  
Rice Husk ◽  
Soybean Protein ◽  
Aqueous Dispersion ◽  
Modulus Of Rupture ◽  
Protein Concentrate ◽  
The Stability ◽  
Soybean Protein Concentrate ◽  
Potential Use

The aim of this research was to prepare an antifungal soybean protein concentrate (SPC) adhesive containing carvacrol (CRV) as a bioactive agent able to delay the attack of molds and yeast during storage of SPC adhesive at 4 °C as water-based systems. CRV was incorporated in SPC slurry at 0.5% v/v (~10 times its minimum inhibitory concentration against Aspergillus terreus, used as model fungus), to ensure its long-term action. CRV scarcely altered the thermal properties, structure and apparent viscosity of SPC adhesive. Active SPC aqueous dispersion was microbiologically stable for at least 30 days at 4 °C where the colonization begins, while control SPC was visually colonized from the second day. Rice husk (RH) particleboards of density ~900 kg/m3 were manufactured using the active SPC stored for 0, 10, 20, and 30 days as a binder. Modulus of elasticity, modulus of rupture and internal bond of RH–control SPC (without CRV) panels were 12.3 MPa, 2.65 GPa and 0.27 MPa, respectively, and were statistically unaltered compared with those obtained with fresh SPC, regardless of the presence of CRV or the storage time. This last implies that active SPC should not necessarily have to be prepared daily and/or be used immediately after its preparation. Since it is microbiologically stabilized, it can be store at least for 30 days, ensuring the stability of the protein. The quality of the adhesive was evidenced by the consistent properties of the adhesive, expanding its potential use and commercialization.

Quality of Reamed Surface Using Serrated Blades as Compared to a Conventional Acetabular Reamer

2013 ◽  
Author(s):  
Annie Levasseur ◽  
Jérémie Ménard ◽  
Victor Songmené ◽  
Julio Fernandes ◽  
Yvan Petit
Keyword(s):  
Experimental Testing ◽  
Three Dimensional ◽  
Laser Scanner ◽  
Numerical Control ◽  
Long Term Stability ◽  
Surface Irregularities ◽  
The Stability ◽  
Acetabular Implant

Background: Hip arthroplasty requires the preparation of the acetabular cavity to allow a proper contact between the bone and the implant. It is essential to allow osseointegration and long-term stability of the implant. The aim of this study was to conduct experimental testing to evaluate the quality of reamed surfaces using a serrated blade acetabular reamer as compared to a conventional rasp reamer. Method of Approach: Reaming tests were performed on a computerized numerical control tools machine at a rotational speed of 250 rpm and 3 different penetration speeds: 0.20 mm/s, 0.55 mm/s and 0.90 mm/s. For each reamer, a complete semi-hemispherical hole was perforated in 7 polyurethane samples. The reamed surfaces were digitized with a three-dimensional high resolution (40 μm) self-positioning laser scanner to carry out a quantitative analysis of the surface quality. Results: Results demonstrated that the cutting edge and the penetration speed influence the quality of the reamed surface. The serrated blade was found to reduce surface irregularities (ranging between 0.19 mm to 0.21 mm for the conventional rasp and between 0.07 mm and 0.12 mm for the serrated blades), and to reduce inaccuracies on the reamed cavity diameter (0.13 mm ± 0.05mm for the rasps and 0.06 mm ± 0.03mm for the serrated blade). Conclusions: The use of such tool by the surgeon may influence the stability of the acetabular implant and reduce the risks of revision surgery.

scholarly journals The Effect of Pulsed Laser Heating on the Stability of Ferropericlase at High Pressures

Minerals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 542
Author(s):  
Georgios Aprilis ◽  
Anna Pakhomova ◽  
Stella Chariton ◽  
Saiana Khandarkhaeva ◽  
Caterina Melai ◽  
...  
Keyword(s):  
High Pressure ◽  
Lower Mantle ◽  
Laser Heating ◽  
High Pressures ◽  
Pulsed Laser ◽  
Experimental Conditions ◽  
Lowermost Part ◽  
The Stability ◽  
Pulsed Laser Heating ◽  
Calcium Silicate Perovskite

It is widely accepted that the lower mantle consists of mainly three major minerals—ferropericlase, bridgmanite and calcium silicate perovskite. Ferropericlase ((Mg,Fe)O) is the second most abundant of the three, comprising approximately 16–20 wt% of the lower mantle. The stability of ferropericlase at conditions of the lowermost mantle has been highly investigated, with controversial results. Amongst other reasons, the experimental conditions during laser heating (such as duration and achieved temperature) have been suggested as a possible explanation for the discrepancy. In this study, we investigate the effect of pulsed laser heating on the stability of ferropericlase, with a geochemically relevant composition of Mg0.76Fe0.24O (Fp24) at pressure conditions corresponding to the upper part of the lower mantle and at a wide temperature range. We report on the decomposition of Fp24 with the formation of a high-pressure (Mg,Fe)3O4 phase with CaTi2O4-type structure, as well as the dissociation of Fp24 into Fe-rich and Mg-rich phases induced by pulsed laser heating. Our results provide further arguments that the chemical composition of the lower mantle is more complex than initially thought, and that the compositional inhomogeneity is not only a characteristic of the lowermost part, but includes depths as shallow as below the transition zone.

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