Differential melting curve

Romer, R., and Hach, R. (1975). tRNA conformation and magnesium binding. A study of a yeast phenylalanine-specific tRNA by a fluorescent indicator and differential melting curves. Eur.J. Biochem. 55(1), 271—284. 

Consequences. An example of experimental results is given in Figure 15.25. Here the fat had been cooled in two steps, i.e., about the regime just discussed. It is seen that the differential melting curve has two maxima, a few kelvins above the crystallizing temperatures applied. It is also seen that these two maxima disappeared upon storage of the fat. This cannot—or more precisely, cannot only—have been due to polymorphic... 

FIGURE 15.25 Differential melting curve (expressed as % of the fat melting per K temperature increase) for a milk fat sample. The fat was held for 1 day at 19°C and then at 10°C for 2h or 8 days. (From data in H. Mulder, P. Walstra. The Milk Fat Globule. Pudoc, Wageningen, 1974.)... 

Figure 2.3. Differential melting curves obtained with poly (dAT dAT) (solid circles), poly (dA dT) (open squares), mitochondrial (open circles) and nuclear DNA from wild-type strain B (solid squares). The ordinate, Y, indicates the increment in relative absorbance per degree of poly (dA dT) had a value...

Figure 2.4. Differential melting curves obtained with mitochondrial DNAs. Every curve is an average from 2 to 5 replicate experiments. Strains A and B are two wild-type strains. Strains ai, a2 and b are spontaneous petite strains. See Fig. 2.3 for other indications. (From Bernardi et al., 1970).

Figure 12. Melting of DNA. (a) The helix-coil transition of a DNA molecule (intramolecular melting), (b) Typical DNA melting profile. This curve is also often called the differential melting curve. The curve was obtained for DNA which has the code name of ColEl and contains about 6500 nucleotide pairs.

Fig. C5.13 Melting curves, 0(T ), upper plots, and differential melting curves, d-d/dT, lower plots, for different sequences, presented at the top (a) poly-A and poly-B homopolymers (b) block-copolymer with 60% A and 40% B (c) heteropolymer with random alternation of the monomer units.

Zinc crystallizes in the hexagonal close-packed system its electronic structure is 4s2 and the melting point is 693 K. Since the zinc dissolution takes place at potentials very close to ffa0 the differential capacitance curves in the region of Ea=c in pure surface-inactive electrolyte solutions (KC1, pH = 3.7) can be determined directly for the Zn(llJO) face only... 

Figure 4. Differential capacity of Pt electrode in carbamide-NH4Cl melt (curve 1) and after 0.5 (curve 2), 1 (curve 3), 1.5 (curve 4), 2 (curve 5) hours of electrolysis.

Figure 9. Differential thermal analysis ofrecrystallized (1) and evaporated (2) MA P (a), and compared melting curves of AMA (1) and POM (2) (b).

Figure 3.2. Differential calorimetric curves for the molecular glasses (a) Spiro-sexiphenyl (second heating curve) and (b) Spiro-PBD (first and second heating curve). The glass transition is indicated by a characteristic step, the melting point by an endothermic peak. In (a) recrystallization occurs above Tg, which can be seen by an exothermic peak. The material in (b) forms a stable amorphous glass without recrystallization. The melting point from the first heating curve of a crystalline sample (dotted line) disappears in the second heating cycle (solid line). Only the glass transition is visible.

FIGURE 3.1 Differential scanning calorimetry melting curves (scan rate 0.04°C/min) of trimyristin dispersions (10% triglyceride stabilized with different concentrations of tyloxapol) with different mean photon correlation spectroscopy z-average diameters. The raw material was dispersed in an aqueous phase containing 1% tyloxapol. (Adapted from [1]. Copyright 2000, American Chemical Society. With permission.)... 

Nuclear magnetic resonance (NMR) can be used as a rapid alternative to differential scanning calorimetry in the determination of the solid fat content and studies on the melting behaviour. The determination is based on detection of the different populations of protons in solid and liquid phases, which indicates the hardness of the fat. Hernandez and Rutledge (1994b) used low resolution pulse NMR to compare melting curves of roasted and non-roasted cocoa butters from Africa, Indonesia and South America. Discriminant analysis techniques showed... 

The polymers mostly used in pharmaceutical packaging are polyethylene, polypropylene, PVC, polyamide, polystyrol, nylon, cellulose acetate, polyethylene terephthtalate, and blends thereof. Copolymers and rubbers are also used. The DSC melting curve of polyethylene used for packaging purposes is characteristic. Low- and high-density polyethylene are differentiated by their melting points. " Melting point and density of polyethylene are linearily correlated. " Crystallinity may be determined as described above for amorphous state. 

Ririe KM, Rasmussen RP, Wittwer CT. Product differentiation by analysis of DNA melting curves during the polymerase chain reaction. Anal Biochem 1997 245 154-60. 

The experimental conditions of DTA necessitate that the AT parameter be plotted as a function of sample temperature, while in DSC the differential power curve is recorded as a function of time. For melting-point determinations, the sample may be encapsulated in the case where the thermocouple must be inserted into the sample, a sample diluent mixture must be employed. The encapsulations are usually in a tightly sealed metal container of high thermal conductivity. In the case of boiling-point determinations, provision must be made for (1) equilibration of liquid and vapor and (2) control of atmospheric pressure. Barrall (39) described in detail how these two criteria can be met. 

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