Experimental Strategies
Clive R. Bagshaw in Biomolecular Kinetics, 2017
In the case of interaction between two macromolecules, aside from any changes in spectral properties, the complexes may show increased light scattering which is sufficient to provide a titration signal [351,352]. Such studies can be carried out in a conventional fluorimeter with the wavelengths of excitation and emission channels set to the same value. Turbidity (apparent absorption) may also be detected in a conventional spectrophotometer. The signal changes are likely to be smaller than for light scattering, but the results are less sensitive to particulate matter in the sample. The best signal will be achieved at the shortest wavelength, which is clear of true absorption effects (typically >300 nm for proteins lacking chromophores). Light scattering and turbidity often provide useful signals to study macromolecular polymerization reactions (Section 5.2). The latter may also be probed using other assays such as dynamic light scattering, fluorescence correlation spectroscopy, or dye-binding [203,353]. Because polymerization reactions give a distribution of product sizes, different assays are likely to give different weighting to the different sizes present. This will affect the apparent kobs values when modeled as a simple reaction mechanism, such as monomer nucleus polymer (Section 5.2).
Mathematical Modeling of Dialysis
Sirshendu De, Anirban Roy in Hemodialysis Membranes, 2017
The efficiency of a hemodialyzer is defined as and , where indices i and o indicate the inlet and the outlet, C denotes concentration of solute and subscripts B and D indicate blood and dialysate sides, respectively, QB and QD indicate blood and dialysate flow rates, respectively. Hence, the following equation results: Simplifying Eq. 7.4930, we have:where NTU is the number of transfer units defined as . The solute transport is thus expressed as
Organic Matter
Michael J. Kennish in Ecology of Estuaries Physical and Chemical Aspects, 2019
Despite similarities between the carbon budgets of these three estuaries, some basic differences are evident. Allochthonous carbon sources predominate in the Dollard estuary, with most carbon (75%) being imported from the North Sea and River Ems (37.1 × 106kg C/year) and from anthropogenic discharges of an industrial facility (33.0 ×106 kg C/year). Carbon import from salt marshes bordering the estuaiy is minimal (0.5 × 106 kg C/year), a reflection of the relatively restricted area of the salt marsh grasses. Autochthonous primary production is low (10 × 106 kg C/year); production by benthic algae (9.3 × 106 kg C/year) — particularly microbenthic algae such as diatoms and dinoflagellates living on or near the sediment surface — greatly surpasses that of phytoplankton (0.7 ×106 kg C/year). Excessive turbidity of the water precludes high phytoplankton production. Because 80% of the estuary consists of tidal flats that support a multitude of detritivores, most carbon is utilized by detritus feeders inhabiting mudflats. The total import and in situ production of organic carbon (80.6 × 106 kg C/year) is substantially greater than the total e×port and utilization (35.56 × 106 kg C/year), a discrepancy ascribed to an unquantified export of DOC from the estuary.
Impact of IgG subclass on molecular properties of monoclonal antibodies
Published in mAbs, 2021
Yu Tang, Paul Cain, Victor Anguiano, James J. Shih, Qing Chai, Yiqing Feng
Turbidity was assessed by microplate spectrofluorometer (SpectraMax M5, San Jose, CA). 100 μL aliquot samples were plated in 96-well Special Optics Black Plates (Corning, Glendale, AZ) and read at ambient temperatures of 20–25°C. Plate based small-volume turbidity analysis (Microturbidity) is a noncompendial method, developed in-house that affords a numerical value to the opalescence and turbidity of mAb formulations. Analysis is based on using absorbance, to measure the amount of light transmission through a sample at a wavelength of 540 nm. The increase or decrease in absorbance can be converted to NTU by a linear regression means using a calibration curve generated from Formazin calibration standards (Millipore Sigma, St. Louis, MO) at various ranges of turbidity. All mAb samples were measured in formulation condition of 90 mg/mL in buffer matrix consisting of 5 mM histidine buffer pH6.0, 280 mM mannitol, and 0.02% (w/v) polysorbate 80. All prepared samples were equilibrated at 5°C over 24 hours prior to measurement.
Removal of heavy metals by conventional water treatment plants using poly aluminum chloride
Published in Toxin Reviews, 2019
Leila Atari, Shirin Esmaeili, Amir Zahedi, Mohammad Javad Mohammadi, Amin Zahedi, Ali Akbar Babaei
The removal of heavy metals in two water treatment plants by using PACl as a coagulant were studied in Ahvaz city. A distinct decrease of the heavy metals concentration except aluminum during the conventional treatment process was obvious implying their removal from the water. Use of PACl as a coagulant will lead to an increase of aluminum in finished water. According to the results, turbidity of the water play a role in the removal of heavy metals and the highest removal occurs in the filtration unit. Metal removal in the rainy season were more than those of dry season and value of heavy metals in treated water were less than raw water except for aluminum. In general, the use of conventional water filtration system with PACl coagulant can reduce the concentration of trace metals except aluminum. Presence of high concentration of Al in drinking water pose deleterious effects on human health, therefore the application of appropriate treatment techniques becomes necessary to keep the concentration of such toxic heavy metals within its desirable limit.
Serum index rules prevent risk of analysing uncentrifuged tubes on automated biochemistry analysers
Published in Scandinavian Journal of Clinical and Laboratory Investigation, 2021
Lars Domino, Peter Astrup Christensen
Autovalidation of results without flags ensures effective use of resources [1]. There are several rules, typically relating to analyte reference range or sample condition e.g. sample clot or HIL interference, resulting in flagged results. While limits to HIL indices are analyte dependent, the results from our two preanalytical incidents, show there is value in the use of lipemia/turbidity measurements, beyond analyte interference testing. The Clinical and Laboratory Standards Institute approved guideline [7] state that turbidity is the result of increased plasma concentrations of lipoproteins, paraproteins, or particulate matter, such as leukocytes and platelets. Our sedimentation result show that the turbidity in no-lipemic lithium heparin plasma is indeed caused by leukocytes and platelets. Lippi et al. [9] also find a correlation between leukocytes, platelets and elevated turbidity in samples. Interestingly, another study by Lippi et al. [8] found a gradual increase in L-indices at room temperature storage of uncentrifuged lithium-heparin samples (i.e. + 16% after 2 h). Additionally, they reported L-indices to be 33% lower in serum than in lithium-heparin plasma. Suggesting that the turbidity is caused by plasma components which are likely bound by the coagulation in serum. Regardless, already used routine turbidity measurements can be used to detectpreanalytical errors.
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