Minutes Of Mixing Research Articles

Investigating Microstructural and Mechanical Behavior of DLP-Printed Nickel Microparticle Composites

The study investigates the fabrication and analysis of nickel microparticle-reinforced composites fabricated using the digital light processing (DLP) technique. A slurry is prepared by incorporating Ni-micro particles into a resin vat; it is thoroughly mixed to achieve homogeneity. Turbidity fluctuations are observed, initially peaking at 50% within the first two minutes of mixing and then stabilizing at 30% after 15–60 min. FTIR spectroscopy with varying Ni wt.% is performed to study the alterations in the composite material’s molecular structure and bonding environment. Spectrophotometric analysis revealed distinctive transmittance signatures at specific wavelengths, particularly within the visible light spectrum, with a notable peak at 532 nm. The effects of printing orientation in the X, Y, and Z axes were also studied. Mechanical properties were computed using tensile strength, surface roughness, and hardness. The results indicate substantial enhancements in the tensile properties, with notable increases of 75.5% in the ultimate tensile strength and 160% in the maximum strain. Minimal alterations in surface roughness and hardness suggest favorable printability. Microscopic examination revealed characteristic fracture patterns in the particulate composite at different values for the wt.% of nickel. The findings demonstrate the potential of DLP-fabricated Ni-reinforced composites for applications demanding enhanced mechanical performance while maintaining favorable printability, paving the way for further exploration in this domain.

The The Effect of Velocity Gradient and Camp Number on Solids Removal using Bio-Coagulant from Corbula faba Hinds Shells

The TSS and TDS values of water are required to meet the standard. Like coagulation, the pretreatment process in water helps reduce solid content in water. The coagulant destabilizes water pollutants and helps flocs formation with the coagulation process. This paper studies the performance of chitosan bio-coagulant produced from Corbula faba Hinds shells. The velocity gradient and the Camp number of solids removal were also evaluated. The velocity and period of rapid mixing varied from 110 to 150 rpm, and the velocity gradient (G) was 181.2 to 288.5 s-1. The mixing period also ranged from 1 to 5 minutes. The highest TSS and TDS removal resulted in 140 rpm or 260.2 s-1 and 4 minutes of mixing. The residual TSS and TDS decreased with the increase of Camp Number until reaching a point and increased again afterward.

Combined effect of limestone fine aggregate and pozzolan on properties of high performance fine-grained concrete

This paper used the absolute volume method combined with the experiment to determine the compositions of high performance fine-grained concrete (HPFC) and presented the effect of limestone fine aggregate (LFA) and pozzolan (PU) on the HPFC properties. Test results showed that by increasing the LFA and PU, the workability of the concrete mixture decreased, the maximum slump loss after 90 minutes of mixing was 37.84%, whereas the mechanical properties of HPFC increased. The fine-grained concrete mixture containing 40% PU and LFA completely replaced material for natural sand, the compressive strength of concrete at 28-day increased about 23.87% in comparison to the control mixture. By using the standard NT Build 356, the destruction time of the four specimens tested was of 45, 63, 60 and 61 days, respectively. This result is due to the presence of PU increased the volume of the C-S-H, as well as the density of concrete structure and enhanced the strength of HPFC, thus increased destruction time of specimens used for the assessment of corrosion damage of reinforced in the concrete. The results of the current study support the use of the waste limestone from the quarries as a fine aggregate of green concrete in the future.

The Influence of Extra Mixing Water on the Properties of Structural Lightweight Aggregate Concrete

Because of high water absorption capacity of lightweight aggregates, the workable concrete mixtures become stiff within a few minutes of mixing. Rather, many ready mix producers will typically pre-wet the aggregate, however this procedure may complicate the technological process. Extra water in structural lightweight aggregate concrete apart workability affects the degree of cement hydration as well as deformation properties of concrete. So, the main objective of this research is to determine the impact of volume of water per cubic meter of concrete needed to be supplied by LWA or by adding extra mixing water on the properties of SLWAC – workability, slump loss, relative humidity change, autogenous shrinkage, and compressive strength.

Properties of Kenaf Bast Powder-Filled High Density Polyethylene/Ethylene Propylene Diene Monomer Composites

High-density polyethylene (HDPE)/ethylene-propylene-diene monomer (EPDM) blend was prepared by mixing HDPE and EPDM in an internal mixer. Kenaf fibers were then added to the mixture with a few minutes of mixing. The tensile properties of the HDPE/EPDM/kenaf composites were investigated using tensile testing and scanning electron microscopy. Treated kenaf bast powder was prepared using hydrochloric acid (HCl). Hydrolysis was carried out to study the effect of HCl on the structure, composition, and properties of the fibers. HCl treatment removed the impurities in the fibers, resulting in smooth fibers with a small particles size. Fourier transform infrared analysis showed a reduction in lignin, wax, and hemicellulose but no modification in surface chemical composition. The treated filled HDPE/EPDM composites had high tensile strength, elongation at break, and modulus than the untreated filled HDPE/EPDM composites.

Nefopam hydrochloride compatibility and stability with selected proton pump inhibitors in bionolyte G5 injection for intravenous infusion

The use of extemporaneously prepared admixtures of drugs must be supported by documentation of their chemical stability. To assess the physical compatibility and the chemical stability of nefopam hydrochloride, a centrally acting non-opioid analgesic, when admixed with selected proton pump inhibitors (omeprazole, esomeprazole or pantoprazole), in bionolyte G5 injection for intravenous infusion. Admixtures were assessed for periods of up to 72 h after storage at ambient temperature without protection from light and at +4 degrees C protected from light. A preparation was considered stable if the compounds of the mixture retained at least 90% of their original potency during the storage. Triplicate samples of nefopam and the selected proton pump inhibitors as well as the following mixtures (nefopam/omeprazole, nefopam/esomeprazole and nefopam/pantoprazole) were prepared in the concentrations required, in polypropylene bottles of bionolyte G5 injection. The physical compatibility was assessed by visual observation at each sampling interval. The chemical stability of the drugs was evaluated by high-performance liquid chromatography and by measurement of pH values. During refrigerated storage, nefopam as well as the selected proton pump inhibitors, when prepared separately in bionolyte G5 injection maintained chemical stability for up to 7 days. At ambient storage conditions, the protons pump inhibitors maintained chemical stability for 24 h, but thereafter their concentrations decreased significantly at day 1. Nefopam maintained chemical stability for up to 72 h at +25 degrees C. Nefopam/omeprazole and nefopam/esomeprazole mixtures in bionolyte were physically incompatible with the mixtures exhibiting a black colour. They underwent rapid and extensive loss, making the combination unacceptable within minutes of mixing. However, the nefopam/pantoprazole mixture was compatible over the study period, but with a reduced duration of the stability. Within the limits defined above, nefopam and the selected proton pump inhibitors may be prepared separately in advance in bionolyte G5 injection. The nefopam/pantoprazole mixture was stable for a short period, while the nefopam/omeprazole and the nefopam/esomeprazole mixtures were incompatible and unusable, immediately upon admixture.

Suitanes

Suitanes

Erosion‐dependant continuity development in high viscosity ratio blends of very low interfacial tension

AbstractThis work studies continuity development and cocontinuity in high viscosity ratio EPDM/PP blends. A very low interfacial tension (0.3 mN/m) between the blend components together with high viscosity ratios (11 and 17) result in a variety of unusual morphological features, including isolated nanometer diameter fibers, very large particles, partially coalesced particles, and numerous particles interconnected by fibers. This unique combination of morphologies leads the blend to a novel and stable cocontinuous structure of partially coalesced particles and particles interconnected by fibers. Compared with low to medium viscosity ratio EPDM/PP blends, these cocontinuous networks demonstrate early percolation thresholds, rapid continuity development, and attain cocontinuity at lower compositions of minor phase. The slow surface erosion of the high viscosity EPDM phase during melt blending is shown to be responsible for the generation of these unusual morphological structures. Typically the timescale for erosion phenomena are so small that they have defied study in the mixing environment itself and typical blend morphology studies almost always examine the final steady‐state morphology obtained after several minutes of mixing. The combination of very low interfacial tension and very high viscosity ratios of these EPDM/PP systems provide a unique opportunity to examine erosion phenomena persisting over longer time scales during melt mixing. We propose a new concentration‐dependant erosion mechanism that is based on particle collision–coalescence–separation dynamics. The proposed conceptual mechanism is shown to dramatically accelerate the erosion process and maintain cocontinuity over prolonged periods of mixing. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1919–1929, 2006

Availability of Danaparoid, an Anticoagulant, for Routine Hematological Tests.

In the Multiphasic Health Check-up System, medical laboratory testing has been changing lately to utilize a small and compact type of testing systems. The system uses heparinized blood for chemistry tests to reduce laboratory's workload and sample volume. The dana-paroid, a mixture of glycosamino-glycans (Heparan sulfate), has been used clinically for treatment of patients with disseminated intravascular coagulopathy instead of heparin sulfate. Heparin has been used for routine laboratory tests, although it has a strong activity of platelet aggregation. This study aimed to examine availability of Danaparoid for routine hematology tests as a substitute of heparin. Although Danaparoid induced platelet aggregation directly, the reaction was weaker than that of heparin. The platelet count of Danaparoid blood was decreased after five minutes of mixing. Addition of MgSO4 or of kanamycin sulfate to Danaparoid blood was able to prevent this decrease. When Danaparoid blood was applied to chemistry tests, major chemistry test data showed acceptable results, although level differences were observed slightly. It was concluded that Danaparoid would be a good candidate for a universal anticoagulant for both chemical and hematological laboratory tests.

Plasma cholesterol: an influencing factor in red blood cell oxygen release and cellular oxygen availability

Background: A fairly immediate reduction in angina pectoris symptoms after cholesterol lowering has been described. Our previous findings in rabbits and in a four-patient human pilot study indicated the existence of an RBC membrane barrier to oxygen (O 2) transport in the presence of hypercholesterolemia. Our current objective was to determine whether, and to what extent, the plasma cholesterol concentration is an influencing factor in RBC O 2 release and cellular O 2 availability. Study Design: In an unique O 2 diffusion analysis system, blood samples from 100 patients referred for lipid modification were analyzed. After 1 to 2 minutes of mixing in our diffusion analysis system, the next 1 to 2 minutes of circulation is comparable with 1 to 2 seconds of myocardial capillary flow. RBC O 2 diffusion was defined by the depletion rate of total O 2 content in blood from full O 2 saturation (98%) to desaturation (approximately 60%). Relative tissue O 2 availability was defined as the percentage decrease in O 2 availability between the high-cholesterol group and the low-cholesterol group. Results: The 100 patients were divided almost equally into two groups on the basis of plasma cholesterol ranges of 175 to 229 mg/dL (n = 49) and 230 to 299 mg/dL (n = 51). The mean cholesterol concentrations and percentage increases in the high-cholesterol group over the low-cholesterol group were: for plasma, 206 ± 0.3 and 256 ± 0.4 mg/dL, 24.3% (p < 0.001); for RBCs, 93 ± 0.2 and 106 ± 0.2 mg/dL, 14.0% (p < 0.001); and for RBC membranes, 41 ± 0.1 and 54 ± 0.2 mg/dL, 31.7% (p < 0.001). The blood O 2 diffusion curves were distinctly different between the high- and the low-cholesterol groups (p < 0.05). Blood O 2 diffusion, defined by the blood O 2 diffusion curves, was inversely proportional to the plasma, RBC, and RBC-membrane cholesterol concentrations. The relative tissue O 2 availability, after a circulation period of more than 3 minutes in the diffusion system, showed a decrease of 17.5% (p < 0.05) between the plasma cholesterol groups. In comparing the two plasma cholesterol concentration extremes of less than 200 mg/dL (n = 14) and greater than 275 mg/dL (n = 11) after a circulation period of more than 3 minutes in the diffusion system, we found a decrease in relative tissue O 2 availability of 35.8% (p < 0.05). Conclusions: The plasma cholesterol concentration may be an influencing factor in RBC-membrane cholesterol content, which, in turn, may regulate RBC-membrane O 2 transport, RBC O 2 release, and cellular O 2 availability. The implications of this work include the addition of angina pectoris control to the indications for appropriate lipid modification and the development of an in vitro blood stress test to replace patient cardiac stress testing.

Control of the Subinclusion Microstructure in HDPE/PS/PMMA Ternary Blends

Various ternary blends of HDPE, PS, and PMMA were prepared in one step using a Brabender mixer. When HDPE is the major component, as in this case, the morphology consists of a HDPE matrix, a PS dispersed phase and PMMA subinclusions within the dispersed PS, as predicted by the spreading coefficients. SEM observation and quantitative characterization were used to show that this complex morphology occurs within the first minutes of mixing and remains stable thereafter. Furthermore, it is shown quantitatively that all the PMMA is present in subinclusion form. It is possible to manipulate the dispersed phase internal structure from small PMMA subinclusions dispersed in a larger PS particle to a PS/PMMA core−shell structure upon decreasing the PS/PMMA composition ratio. Coalescence of composite droplets was also investigated. Upon annealing, these systems clearly experience a dual coalescence process: composite droplet/composite droplet coalescence and coalescence between dispersed subinclusion particles. Alt...

Sedimentation of free and attached Cryptosporidium oocysts and Giardia cysts in water.

Experimental analysis of the sedimentation velocity of Cryptosporidium parvum oocysts and Giardia lamblia cysts was compared with mathematical description of their sedimentation velocities by using measurements of (oo)cyst size and density and the density and viscosity of the sedimentation medium to determine if the sedimentation kinetics of freely suspended oocysts of C. parvum and cysts of G. lamblia can be described by Stokes' law. The theoretically calculated sedimentation kinetics showed a good agreement with the experimentally observed kinetics. Both showed a decline in sedimentation velocity over time, caused primarily by variation in (oo)cyst density. The initial apparent sedimentation velocities in Hanks balanced salt solution at 23 degrees C was 0.35 micron . s-1 for oocysts and 1.4 micron . s-1 for cysts. (Oo)cysts that enter the surface water environment by discharges of biologically treated sewage may be attached to sewage particles, and this will affect their sedimentation kinetics. Therefore, (oo)cysts were mixed with settled secondary effluent. (Oo)cysts readily attached to the (biological) particles in effluent; 30% of both cysts and oocysts attached during the first minutes of mixing, and this fraction increased to approximately 75% after 24 h. The sedimentation velocity of (oo)cysts attached to secondary effluent particles increased with particle size and was (already in the smallest size fraction [1 to 40 micron]) determined by the sedimentation kinetics of the effluent particles. The observed sedimentation velocities of freely suspended (oo)cysts are probably too low to cause significant sedimentation in surface water or reservoirs. However, since a significant proportion of both cysts and oocysts attached readily to organic biological particles in secondary effluent, sedimentation of attached (oo)cysts after discharge into surface water will probably be a significant factor in the environmental ecology of C. parvum and G. lamblia. Attachment to particles influences not only sedimentation of (oo)cysts in surface water but also their behavior in drinking water treatment processes.

Rapid loss of fentanyl citrate admixed with fluorouracil in polyvinyl chloride containers.

To study the physical compatibility and chemical stability of fluorouracil 1 and 16 mg/mL with fentanyl citrate 12.5 micrograms/mL in dextrose 5% and in sodium chloride 0.9% injection. Test solutions of the drugs in dextrose 5% injection and in sodium chloride 0.9% injection were prepared in triplicate and stored at -20, 4, 23, and 32 degrees C. Samples were removed immediately and at various times over 7 days and stored at -70 degrees C until analyzed. Physical compatibility was assessed visually and by measuring turbidity with a color-correcting turbidimeter; particle content was measured with a light-obscuration particle sizer and counter. Chemical stability was determined by measuring the concentration of each drug in the test solutions in duplicate with stability-indicating HPLC. Fentanyl citrate was rapidly lost when admixed with fluorouracil in polyvinyl chloride (PVC) containers, losing about 25% in the first 15 minutes and about 50% in the first hour. The loss of fentanyl citrate was so rapid that accurate time zero determinations were not possible. The extent of fentanyl loss increased with time and occurred more rapidly at the higher temperatures (i.e., 23, 32 degrees C). Losses of 70% or more occurred in all samples within 24 hours. Fentanyl underwent rapid sorption to the containers at the high pH (9.0-9.5) of the fluorouracil admixtures. Adjusting the pH of a fentanyl citrate solution (containing no fluorouracil) in PVC containers to pH 9 with sodium hydroxide also resulted in rapid sorption loss. Fentanyl citrate sorption did not occur when admixtures were prepared in polyethylene containers. Fluorouracil remained stable for at least 7 days at all temperatures. There were no visual or subvisual changes in turbidity or particle content in any of the test solutions at any time. When admixed with fluorouracil 1 and 16 mg/mL in dextrose 5% injection and sodium chloride 0.9% injection, fentanyl citrate 12.5 micrograms/mL underwent rapid and extensive loss due to sorption to the PVC containers, making the combination unacceptable within minutes of mixing. The sorption results from the alkaline pH of the admixture and, presumably, could occur from the admixture of fentanyl citrate with any sufficiently alkaline drug.

Moisture Transfer in Blended Long-grain Rough Rice

Moisture transfer in mixtures of low- and high-moisture content (MC) rough rice (ranging from 9.5 to 18.0% w.b.) was investigated with a single-kernel moisture tester over a period of 30 days. The intergranular air attained constant relative humidity corresponding to the mean MC of the mixture within a few minutes of mixing. About 90% of the change in the MC of low- and high-MC kernels occurred within first one or two days of mixing even though moisture exchange continued over a period of 30 days. Changes in standard deviation (SD) of MC of the mixture with time, when normalized as a SD ratio, were similar to simulated changes in MCs of low- and high-MC fractions relative to their mean MC. The developed relationships can be used to estimate the MC variation with time in low- and high-MC fractions of mixed rough rice.

Saturation Factors for Calcium Hydroxide and Calcium Sulfates in Fresh Portland Cement Pastes

Aqueous extracts from five cement pastes at w/c = 0.5 were analyzed for Ca2+, SO2–4, Na+, and K+. Degrees of saturation with respect to portlandite, gypsum, and syngenite were determined at ages from 6 min to 3 h, taking into account ionic association effects. Portlandite saturation is usually attained within a few minutes of mixing, but rates of saturation vary. The maximum degree of saturation is 2 to 3 times the equilibrium value and is attained within 2 h. Initial super‐saturation with respect to gypsum, and in some cases syngenite, occurs at very early ages and declines to the saturation level within 12 min. Results are interpreted by use of a solution‐precipitation model for cement hydration. The calculated critical size of portlandite nuclei at early ages is ∼0.1 μm. Slow growth of portlandite nuclei suggests a surface poisoning phenomenon.

A stationary cold vapor method for atomic absorption measurement of mercury in blood and urine used for exposure screening

A method is provided for rapid, accurate flameless atomic absorption Hg determinations in blood and urine used for exposure screening of mercury. Instead of the conventional apparatus requiring separate reduction and absorption containers, a one-piece reduction-absorption cell was fitted on the burner mount of an atomic absorption spectrophotometer. A five mL aliquot of the digested urine or blood sample was pipetted into the cell and one mL reductant added. The background corrected absorbance was recorded after three minutes of mixing. Heating the absorption cell at 60°C eliminated the formation of water vapor on the quartz windows of the tube. Sensitivity of the method was 1.0 ng which corresponds to a concentration of 0.2 ng/mL using a 5 mL sample size. The accuracy of Hg determinations in human blood and urine was confirmed by the method of standard additions of Hg to undigested samples. In order to test the applicability of the method to biological samples from Hg exposed individuals, rats were injected i.p. with 0.0 to 0.10 mg Hg as HgCl2. A dose related increase in Hg levels was observed in blood and urine collected at 24 hours after dosing. In addition, Hg was measured in human blood and urine samples obtained from 11 males not known to be recently exposed to Hg, indicating that the method is applicable to Hg exposure screening commonly used in industrial hygiene. The analysis can be conducted in less than 4 minutes each with a semi-automated sampling and cleaning capability and multiple Hg determinations performed on a single sample digest.

A stationary cold vapor method for atomic absorption measurement of mercury in blood and urine used for exposure screening

A method is provided for rapid, accurate flameless atomic absorption Hg determinations in blood and urine used for exposure screening of mercury. Instead of the conventional apparatus requiring separate reduction and absorption containers, a one-piece reduction-absorption cell was fitted on the burner mount of an atomic absorption spectrophotometer. A five mL aliquot of the digested urine or blood sample was pipetted into the cell and one mL reductant added. The background corrected absorbance was recorded after three minutes of mixing. Heating the absorption cell at 60°C eliminated the formation of water vapor on the quartz windows of the tube. Sensitivity of the method was 1.0 ng which corresponds to a concentration of 0.2 ng/mL using a 5 mL sample size. The accuracy of Hg determinations in human blood and urine was confirmed by the method of standard additions of Hg to undigested samples. In order to test the applicability of the method to biological samples from Hg exposed individuals, rats were injec...

The Design and Operation of Intermittently Operated Water Purification Plants

In our experience in the design and operation of water filtration plants, we have learned that the plant with intermittent operation presents the most difficult problems. The practice in the past has been to depend almost entirely on the filters themselves, for the overall efficiency of the plant, and to give very little attention to the design of the settling and coagulating basins. There is little question but what the action in the basins and in the filters themselves is equally important in getting good and economical results in any filtration plant. This fact is most emphatically true of plants which are operated intermittently. In cases where the plant is operated perhaps ten hours each day, it is difficult to get the proper conditions of water applied to the filters during the first part of each run, as the floe has almost always settled out so as to cause the first water applied to the filters to be clear, or practically so, and free from floe. The arranging of the basins so as to make it possible to handle this clear water and to prepare it for application on the filters is one of the most difficult features in the design. It is a pretty well established fact that thorough mixing of the chemical and the raw water when first pumped into the basins is well worth the cost. There is always some question as to just how far it is wise to carry this mixing, as each water presents a separate study in itself. There are so many things that enter into the action, such as temperature, turbidity, etc., that no set length of time can be taken as the proper time for mixing. The length of time also depends on the degree of agitation. If the mixing is obtained by means of mechanically driven agitators, the time required is much less than when obtained by baffling. To meet different temperatures, and different conditions of the water, it is probably best to subject the water to at least thirty minutes of mixing when mechanically driven agitators are used, and at least an hour where