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Materials (Basel, Switzerland) Mar 2021This review was focused on expressing the effects of base liquid, temperature, possible surfactant, concentration and characteristics of nanoparticles including size,... (Review)
Review
This review was focused on expressing the effects of base liquid, temperature, possible surfactant, concentration and characteristics of nanoparticles including size, shape and material on thermal conductivity and viscosity of nanofluids. An increase in nanoparticle concentration can lead to an increase in thermal conductivity and viscosity and an increase in nanoparticle size, can increase or decrease thermal conductivity, while an increase in nanoparticle size decreases the viscosity of the nanofluid. The addition of surfactants at low concentrations can increase thermal conductivity, but at high concentrations, surfactants help to reduce thermal conductivity of the nanofluid. The addition of surfactants can decrease the nanofluid viscosity. Increasing the temperature, increased the thermal conductivity of a nanofluid, while decreasing its viscosity. Additionally, the effects of material of nanoparticles on the thermal conductivity and viscosity of a nanofluid need further investigations. In the case of hybrid nanofluids, it was observed that nanofluids with two different particles have the same trend of behavior as nanofluids with single particles in the regard to changes in temperature and concentration. Additionally, the level of accuracy of existing theoretical models for thermal conductivity and viscosity of nanofluids was examined.
PubMed: 33800374
DOI: 10.3390/ma14051291 -
International Journal of Molecular... Jan 2020Platelet cryopreservation has been investigated for several decades as an alternative to room temperature storage of platelet concentrates. The use of dimethylsulfoxide... (Review)
Review
Platelet cryopreservation has been investigated for several decades as an alternative to room temperature storage of platelet concentrates. The use of dimethylsulfoxide as a cryoprotectant has improved platelet storage and cryopreserved concentrates can be kept at -80 °C for two years. Cryopreserved platelets can serve as emergency backup to support stock crises or to disburden difficult logistic areas like rural or military regions. Cryopreservation significantly influences platelet morphology, decreases platelet activation and severely abrogates platelet aggregation. Recent data indicate that cryopreserved platelets have a procoagulant phenotype because thrombin and fibrin formation kicks in earlier compared to room temperature stored platelets. This happens both in static and hydrodynamic conditions. In a clinical setting, low 1-h post transfusion recoveries of cryopreserved platelets represent fast clearance from circulation which may be explained by changes to the platelet GPIbα receptor. Cryopreservation splits the concentrate in two platelet subpopulations depending on GPIbα expression levels. Further research is needed to unravel its physiological importance. Proving clinical efficacy of cryopreserved platelets is difficult because of the heterogeneity of indications and the ambiguity of outcome measures. The procoagulant character of cryopreserved platelets has increased interest for use in trauma stressing the need for double-blinded randomized clinical trials in actively bleeding patients.
Topics: Blood Platelets; Blood Specimen Collection; Cryopreservation; Fibrin; Humans; Platelet Aggregation; Thrombin
PubMed: 32023815
DOI: 10.3390/ijms21030935 -
Frontiers in Physiology 2018Neocytolysis is the selective destruction of those erythrocytes that had been formed during stress-erythropoiesis in hypoxia in order to increase the oxygen transport... (Review)
Review
Neocytolysis is the selective destruction of those erythrocytes that had been formed during stress-erythropoiesis in hypoxia in order to increase the oxygen transport capacity of blood. Neocytolysis likely aims at decreasing this excess amount of erythrocytes and hemoglobin (Hb) when it is not required anymore and to decrease blood viscosity. Neocytolysis seems to occur upon descent from high altitude. Similar processes seem to occur in microgravity, and are also discussed to mediate the replacement of erythrocytes containing fetal hemoglobin (HbF) with those having adult hemoglobin (HbA) after birth. This review will focus on hypoxia at high altitude. Hemoglobin concentration and total hemoglobin in blood increase by 20-50% depending on the altitude (i.e., the degree of hypoxia) and the duration of the sojourn. Upon return to normoxia hemoglobin concentration, hematocrit, and reticulocyte counts decrease faster than expected from inhibition of stress-erythropoiesis and normal erythrocyte destruction rates. In parallel, an increase in haptoglobin, bilirubin, and ferritin is observed, which serve as indirect markers of hemolysis and hemoglobin-breakdown. At the same time markers of progressing erythrocyte senescence appear even on reticulocytes. Unexpectedly, reticulocytes from hypoxic mice show decreased levels of the hypoxia-inducible factor HIF-1α and decreased activity of the BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (BNIP3), which results in elevated mitochondrial activity in these cells. Furthermore, hypoxia increases the expression of miR-21, which inhibits the expression of catalase and thus decreases one of the most important mechanisms protecting against oxygen free radicals in erythrocytes. This unleashes a series of events which likely explain neocytolysis, because upon re-oxygenation systemic and mitochondrial oxygen radical formation increases and causes the selective destruction of those erythrocytes having impaired anti-oxidant capacity.
PubMed: 29674976
DOI: 10.3389/fphys.2018.00345 -
Journal of Lipid Research Oct 2016An elevated plasma concentration of lipoprotein (a) [Lp(a)] is an independent risk factor for cardiovascular disease. Life style modification and currently available... (Review)
Review
An elevated plasma concentration of lipoprotein (a) [Lp(a)] is an independent risk factor for cardiovascular disease. Life style modification and currently available drugs either fail to effectively lower plasma Lp(a) levels or do not result in clinical benefit. However, lipoprotein apheresis is very efficient in decreasing Lp(a) concentrations. A single apheresis session can acutely decrease Lp(a) by approximately 60-75%, and apheresis performed weekly or biweekly results in considerably decreased mean interval concentrations (approximately 25-40% reduction). While most apheresis systems (heparin-induced extracorporeal LDL precipitation, direct adsorption of lipoproteins, lipoprotein apheresis with dextran-sulfate, lipid filtration, immunoadsorption) decrease LDL and Lp(a), Lipopac is specific and only decreases Lp(a). Lp(a) apheresis is expensive and time consuming, but associated with very few side effects. Two randomized controlled trials give conflicting consults with respect to the effect on angiographic changes. Retrospective analyses indicate that regular apheresis translates into clinical benefit in patients with elevated Lp(a), but adequate randomized controlled trials are lacking.
Topics: Blood Component Removal; Dextran Sulfate; Humans; Lipoprotein(a); Lipoproteins, LDL; Randomized Controlled Trials as Topic
PubMed: 26889050
DOI: 10.1194/jlr.R056549 -
Separation and Purification Technology May 2020Even though numerous methods have been developed for the detection and quantification of waterborne pathogens, the application of these methods is often hindered by the...
Even though numerous methods have been developed for the detection and quantification of waterborne pathogens, the application of these methods is often hindered by the very low pathogen concentrations in natural waters. Therefore, rapid and efficient sample concentration methods are urgently needed. Here we present a novel method to pre-concentrate microbial pathogens in water using a portable 3D-printed system with super-absorbent polymer (SAP) microspheres, which can effectively reduce the actual volume of water in a collected sample. The SAP microspheres absorb water while excluding bacteria and viruses by size exclusion and charge repulsion. To improve the water absorption capacity of SAP in varying ionic strength waters (0-100 mM), we optimized the formulation of SAP to 180 g⋅L Acrylamide, 75 g⋅L Itaconic Acid and 4.0 g⋅L Bis-Acrylamide for the highest ionic strength water as a function of the extent of cross-linking and the concentration of counter ions. Fluorescence microscopy and double-layer agar plating respectively showed that the 3D-printed system with optimally-designed SAP microspheres could rapidly achieve a 10-fold increase in the concentration of () and bacteriophage MS2 within 20 min with concentration efficiencies of 87% and 96%, respectively. Fold changes between concentrated and original samples from qPCR and RT-qPCR results were found to be respectively 11.34-22.27 for with original concentrations from 10 to 10 cell·mL, and 8.20-13.81 for MS2 with original concentrations from 10 to 10 PFU·mL. Furthermore, SAP microspheres can be reused for 20 times without performance loss, significantly decreasing the cost of our concentration system.
PubMed: 32421015
DOI: 10.1016/j.seppur.2020.116540 -
Journal of Veterinary Internal Medicine Nov 2022Albuterol by inhalation (IH) is a common treatment for hyperkalemia in humans but its effect on blood potassium concentrations in dogs is unknown.
BACKGROUND
Albuterol by inhalation (IH) is a common treatment for hyperkalemia in humans but its effect on blood potassium concentrations in dogs is unknown.
OBJECTIVE
Determine whether albuterol (IH) decreases blood potassium concentrations in healthy normokalemic dogs and if effects are dose-dependent.
ANIMALS
Ten healthy dogs.
METHODS
Prospective, crossover experimental study. Albuterol sulfate was administered at a low-dose (90 μg) in phase I and, 7 days later, high-dose (450 μg) in phase II. Blood potassium and glucose concentrations (measured via blood gas analyzer) and heart rates were obtained at baseline and then 3, 5, 10, 15, 30, 60, 90, 120, 180, and 360 minutes after inhaler actuation.
RESULTS
Blood potassium concentrations decreased rapidly after albuterol delivery with a significant reduction compared to baseline within 30 minutes in both phases (P = .05). The potassium nadir concentration of phase I occurred at 60 minutes (mean, SD; 4.07 mmol/L, 0.4) and was significantly decreased from baseline, (4.30 mmol/L, 0.3; t(9) = 2.40, P = .04). The potassium nadir concentration of phase II occurred at 30 minutes (mean, SD; 3.96 mmol/L, 0.39) and was also significantly decreased from baseline, (4.33 mmol/L, 0.4; t(9) = 2.22, P = .05). The potassium nadir concentration decreased by 0.1 mmol/L for each 10 μg/kg increase in dose of albuterol (P = .01). Five dogs had ≥1 hyperglycemic measurement (ie, >112 mg/dL). No median heart rate was tachycardic nor was any mean blood glucose concentration hyperglycemic at any time point.
CONCLUSION AND CLINICAL IMPORTANCE
Albuterol IH decreases blood potassium concentrations in a dose-dependent manner without clinically meaningful alterations to heart rate or blood glucose concentrations in healthy dogs. The mean decrease in potassium concentration at the high-dose of albuterol was modest (0.38 mmol/L).
Topics: Humans; Dogs; Animals; Albuterol; Potassium; Prospective Studies; Blood Glucose; Hyperkalemia; Dog Diseases
PubMed: 36178135
DOI: 10.1111/jvim.16552 -
Journal of Dairy Science Jul 2021Concentration of milk in the dairy industry is typically achieved by thermal evaporation or reverse osmosis (RO). Heat concentration is energy intensive and leads to...
Concentration of milk in the dairy industry is typically achieved by thermal evaporation or reverse osmosis (RO). Heat concentration is energy intensive and leads to cooked flavor and color changes in the final product, and RO is affected by fouling, which limits the final achievable concentration of the product. The main objective of this work was to evaluate forward osmosis (FO) as an alternative method for concentrating milk. The effects of fat content and temperature on the process were evaluated, and the physicochemical properties and sensory qualities of the final product were assessed. Commercially pasteurized skim and whole milk samples were concentrated at 4, 15, and 25°C using a benchtop FO unit. The FO process was assessed by monitoring water flux and product concentration. The color of the milk concentrates was also evaluated. A sensory panel compared the FO concentrated and thermally concentrated milks, diluted to single strength, with high temperature, short time pasteurized milk. The FO experimental runs were conducted in triplicate, and data were analyzed by single-factor ANOVA. Water flux during FO decreased with time under all processing conditions. Higher temperatures led to faster concentration and higher concentration factors for both skim and whole milk. After 5.75 h of FO processing, the concentration factors achieved for skim milk were 2.68 ± 0.08 at 25°C, 2.68 ± 0.09 at 15°C, and 2.36 ± 0.08 at 4°C. For whole milk, after 5.75 h of FO processing, concentration factors of 2.32 ± 0.12 at 25°C, 2.12 ± 0.36 at 15°C, and 1.91 ± 0.15 at 4°C were obtained. Overall, maximum concentration levels of 40.15% total solids for skim milk and 40.94% total solids for whole milk were achieved. Additionally, a triangle sensory test showed no significant differences between regular milk and FO concentrated milk diluted to single strength. This work shows that FO is a viable nonthermal processing method for concentrating milk, but some technical challenges need to be overcome to facilitate commercial utilization.
Topics: Animals; Filtration; Flavoring Agents; Membranes, Artificial; Milk; Osmosis; Taste
PubMed: 33865601
DOI: 10.3168/jds.2020-20019 -
Annals of Botany Feb 2009In contrast to C(3) photosynthesis, the response of C(4) photosynthesis to water stress has been less-well studied in spite of the significant contribution of C(4)... (Review)
Review
BACKGROUND
In contrast to C(3) photosynthesis, the response of C(4) photosynthesis to water stress has been less-well studied in spite of the significant contribution of C(4) plants to the global carbon budget and food security. The key feature of C(4) photosynthesis is the operation of a CO(2)-concentrating mechanism in the leaves, which serves to saturate photosynthesis and suppress photorespiration in normal air. This article reviews the current state of understanding about the response of C(4) photosynthesis to water stress, including the interaction with elevated CO(2) concentration. Major gaps in our knowledge in this area are identified and further required research is suggested.
SCOPE
Evidence indicates that C(4) photosynthesis is highly sensitive to water stress. With declining leaf water status, CO(2) assimilation rate and stomatal conductance decrease rapidly and photosynthesis goes through three successive phases. The initial, mainly stomatal phase, may or may not be detected as a decline in assimilation rates depending on environmental conditions. This is because the CO(2)-concentrating mechanism is capable of saturating C(4) photosynthesis under relatively low intercellular CO(2) concentrations. In addition, photorespired CO(2) is likely to be refixed before escaping the bundle sheath. This is followed by a mixed stomatal and non-stomatal phase and, finally, a mainly non-stomatal phase. The main non-stomatal factors include reduced activity of photosynthetic enzymes; inhibition of nitrate assimilation, induction of early senescence, and changes to the leaf anatomy and ultrastructure. Results from the literature about CO(2) enrichment indicate that when C(4) plants experience drought in their natural environment, elevated CO(2) concentration alleviates the effect of water stress on plant productivity indirectly via improved soil moisture and plant water status as a result of decreased stomatal conductance and reduced leaf transpiration.
CONCLUSIONS
It is suggested that there is a limited capacity for photorespiration or the Mehler reaction to act as significant alternative electron sinks under water stress in C(4) photosynthesis. This may explain why C(4) photosynthesis is equally or even more sensitive to water stress than its C(3) counterpart in spite of the greater capacity and water use efficiency of the C(4) photosynthetic pathway.
Topics: Carbon; Carbon Dioxide; Dehydration; Droughts; Photosynthesis; Plant Stomata; Water
PubMed: 18552367
DOI: 10.1093/aob/mcn093 -
Journal of Dairy Science Dec 2021Our objective was to determine the effects of temperature and protein concentration on viscosity increase and gelation of liquid micellar casein concentrate (MCC) at...
Our objective was to determine the effects of temperature and protein concentration on viscosity increase and gelation of liquid micellar casein concentrate (MCC) at protein concentrations from 6 to 20% during refrigerated storage. Skim milk (∼350 kg) was pasteurized (72°C for 16 s) and filtered through a ceramic microfiltration system to make MCC and replicated 3 times. The liquid MCC was immediately concentrated via a plate ultrafiltration system to 18% protein (wt/wt). The MCC was then diluted to various protein concentrations (6-18%, wt/wt). The highest protein concentrations of MCC formed gels almost immediately on cooling to 4°C, whereas lower concentrations of MCC were viscous liquids. Apparent viscosity (AV) determination using a rotational viscometer, gel strength using a compression test, and protein analysis of supernatants from ultracentrifugation by the Kjeldahl method were performed. The AV data were collected from MCC (6.54, 8.75, 10.66, and 13.21% protein) at 4, 20, and 37°C, and compression force test data were collected for MCC (15.6, 17.9, and 20.3% protein) over a period of 2-wk storage at 4°C. The maximum compressive load was compared at each time point to determine the changes in gel strength over time. Supernatants from MCC of 6.96 and 11.61% protein were collected after ultracentrifugation (100,605 × g for 2 h at 4, 20, and 37°C) and the nitrogen distributions (total, noncasein, casein, and nonprotein nitrogen) were determined. The protein and casein as a percent of true protein concentration in the liquid phase around casein micelles in MCC increased with increasing total MCC protein concentration and with decreasing temperature. Casein as a percent of true protein at 4°C in the liquid phase around casein micelles increased from about 16% for skim milk to about 78% for an MCC containing 11.6% protein. This increase was larger than expected, and this may promote increased viscosity. The AV of MCC solutions in the range of 6 to 13% casein increased with increasing casein concentration and decreasing temperature. We observed a temperature by protein concentration interaction, with AV increasing more rapidly with decreasing temperature at high protein concentration. The increase in AV with decreasing temperature may be due to the increase in protein concentration in the aqueous phase around the casein micelles. The MCC containing about 16 and 18% casein gelled upon cooling to form a gel that was likely a particle jamming gel. These gels increased in strength over 10 d of storage at 4°C, likely due either to the migration of casein (CN) out of the micelles and interaction of the nonmicellar CN to form a network that further strengthened the random loose jamming gel structure or to a gradual increase in voluminosity of the casein micelles during storage at 4°C.
Topics: Animals; Caseins; Gels; Micelles; Milk; Viscosity
PubMed: 34531054
DOI: 10.3168/jds.2021-20658 -
Journal of Dairy Science Jun 2019The colloidal properties of the casein micelles play a major role in the structural properties of milk protein concentrates. Because of their great technological... (Review)
Review
The colloidal properties of the casein micelles play a major role in the structural properties of milk protein concentrates. Because of their great technological importance, the structural-functional relationships of casein micelles have been studied for decades in skim milk; however, novel ingredients are now available with higher protein concentrations and varying in composition. The colloidal behavior of caseins in these systems is not fully understood. Concentrates prepared with membrane technologies, and subjected to pre- or post-modifications that affect their technological functionality, have become increasingly widespread. This has created large opportunities for innovation and generation of value-added ingredients. The manner in which caseins interact with themselves and the other components in these concentrates will affect the structure of the final matrix. During concentration by filtration, the interparticle distance between the micelles decreases considerably, increasing their spatial correlation and decreasing their diffusivity. Rearrangements occur due to changes in environmental conditions, such as ionic composition, osmotic stress, shear, pH, or heating temperature. This will have important consequences on bulk viscosity of the concentrates, as well as on the mode of formation of structures' building blocks. This paper aims at highlighting some of the important factors affecting the colloidal structure of casein micelles, their destabilization and network formation, namely, processing history, volume fraction, composition of the serum phase, and ionic equilibrium. Understanding these factors will lead to a better quality control of dairy ingredients and to the development of a new generation of ingredients with targeted functionality.
Topics: Animals; Caseins; Cattle; Micelles; Milk; Milk Proteins
PubMed: 30981474
DOI: 10.3168/jds.2018-15943