Heating Run Research Articles

Counter-intuitive effect of non-crystallizing sugars on the crystallization of gemcitabine HCl in frozen solutions

In this study, the effect of four non-crystallizing sugars, namely fructose, trehalose, sucrose and raffinose, was assessed on the crystallization of gemcitabine hydrochloride (GHCl) in frozen solutions. Aqueous solutions containing GHCl (50mg/mL) and a sugar at varying concentrations (10–60mg/mL) were frozen in situ in DSC and analyzed in the subsequent heating run. Crystallization propensity of GHCl was quantified in terms of reduced crystallization temperature (RCT) as a function of sugar type and concentration. Multivariate analysis option in JMP® software was employed for calculating correlation between the variables. All sugars inhibited GHCl crystallization in a concentration dependent manner. At equal concentration, fructose (with the lowest Tg′) exerted the strongest inhibitory effect, whereas raffinose (with the highest Tg′) exerted the weakest inhibitory effect. Additionally, RCT showed a poor correlation with Tg′ (r=0.2327). Thus, the inhibitory effect of sugars could not be described by their anti-plasticization effect. This counter-intuitive behavior was explained by the inhibitory effect of sugars on ice crystallization, which increased the unfrozen water content (UWC) in the freeze concentrate, thereby lowering the supersaturation of GHCl. This was established by observing a good correlation (r=0.9666) between RCT and ln(1/UWC). Additionally, reduced diffusion kinetics of GHCl in presence of sugar molecules was also postulated. This study highlights the importance of unfrozen water towards governing the crystallization behavior of solutes in multi-component frozen systems.

Differential effect of buffering agents on the crystallization of gemcitabine hydrochloride in frozen solutions.

The purpose of this study was to evaluate the differential effect of buffering agents on the crystallization of gemcitabine hydrochloride (GHCl) in frozen solutions. Four buffering agents, viz. citric acid (CA), malic acid (MA), succinic acid (SA) and tartaric acid (TA) were selected and their effect on GHCl crystallization was monitored using standard DSC and low temperature XRD. Onset of GHCl crystallization during heating run in DSC was measured to compare the differential effect of buffering agents. Glass transition temperature (Tg'), unfrozen water content in the freeze concentrate and crystallization propensity of the buffering agents was also determined for mechanistic understanding of the underlying effects. CA and MA inhibited while SA facilitated crystallization of GHCl even at 25 mM concentration. Increasing the concentration enhanced their effect. However, TA inhibited GHCl crystallization at concentrations <100mM and facilitated it at concentrations ≥100 mM. Lyophilization of GHCl with either SA or TA yielded elegant cakes, while CA and MA caused collapse. Tg' failed to explain the inhibitory effects of CA, MA and TA as all buffering agents lowered the Tg' of the system. Differential effect of buffering agents on GHCl crystallization could be explained by consideration of two opposing factors: (i) their own crystallization tendency and (ii) unfrozen water content in the freeze concentrate. In conclusion, it was established that API crystallization in frozen solution is affected by the type and concentration of the buffering agents.

Thermal dehydroxylation of kaolinite under isothermal conditions

The dehydroxylation reaction of kaolinite from the industrial kaolin Sl-K (Germany) has been studied by thermal analyses (TG, DTA) and ex situ annealing experiments. Heating experiments were performed at 450, 500, 550 and 600°C. At each working temperature, different heating times were used in order to follow the evolution of the dehydroxylation process with time until completion of the reaction. Every heating run was performed on a new batch of sample, which was weighted before and after the heat-treatment. At the end of the heating run, each sample was characterised by X-ray powder diffraction (XRPD) and FT-infrared attenuated total reflectance spectroscopy (FTIR-ATR). The dehydroxylation process was followed by monitoring the gradual mass loss and the corresponding decrease in intensity of the most significant peaks both in the diffraction patterns (disappearing of kaolinite peaks) and in the FTIR-ATR spectra (disappearing and changes in OH and SiOAl bands), as determined by peak-profile and autocorrelation analyses. A kinetic analysis was performed using the Avrami method on the basis of sample mass loss and changes in the intensities of XRPD and FTIR-ATR peaks under isothermal conditions. Two temperature regimes are found, with only the data in range 500–600°C being isokinetic. The activation energy values obtained in this temperature range on the basis of the three measured parameters are comparable and are between 127 and 139kJmol−1.

Residual stress evolution of polymethylsilsesquioxane thin films with organic templates

Polymethylsilsesquioxanes (PMSSQs) and star-shaped 4 arm poly(ε-caprolactone)s (PCLs) were homogeneously mixed and chemically linked in their composites. Nanoporous PMSSQ films were made by curing and calcination of the composite films at the elevated temperature. The residual stresses of nanoporous PMSSQ films were analyzed to investigate the reliability of films in the multilayer devices. The residual stresses of PMSSQ/PCL composite films were highly dependent on factors such as the amount of the initial PCL loading and thermal process. The final stresses of nanoporous PMSSQ films ranged from 20 to 50MPa at room temperature, depending on the initial PCL loadings. On heating run, the residual stress of the composite film was attributed to the competition between the relaxation and the curing of matrix polymers. On cooling run, the residual stress of nanoporous PMSSQ film was mainly due to the increased cure density, and the dimension shrinkage of networked matrix polymers.

Successive phase transitions in [C(NH2)3]4Cl2SO4 crystal—dielectric, pyroelectric and optical evidences

Studies of the dielectric and pyroelectric properties of a [C(NH2)3]4Cl2SO4 crystal along the ferroelectric c-axis and the optical observation along the b-axis in the temperature range 330–380K covering the phase transitions region were performed with various heating/cooling rates. At faster heating, a diffused dielectric anomaly in the range of phase transitions was observed. Slow heating (0.01K/min) shows two successive phase transitions: III→II at T2h=354.5K and II→I at T1h=357.5K. Pyroelectric studies showed polar properties of phases III and II. The disappearance of polarization is diffused at the first heating run. The sample kept for 400min in phase II undergoes a direct sharp II→I transition during heating. Optical observations on the heating run at a 0.01K/min rate confirmed successive phase transitions with symmetry changes according to a scheme: orthorhombic (III)→orthorhombic (II)→tetragonal (I). The dielectric, pyroelectric and optical studies revealed a slow III→II transition. On the cooling run, we deal with one transition at T1c equal to 355K between the tetragonal phase (I) and the orthorhombic phase (II).

Self-Assembly Behavior of N-Methly-N-Hexadecyl-Pyrrolidinium Bromide in Water

N-methyl-N-hexadecylpyrrolidinium bromide (IL) was synthesized for the design of ionic liquid crystals which is a fascinating class of molecular materials, offering the combination of order and mobility. In binary mixtures with water, lyotropic liquid crystalline phase appears in the range of IL content from 35% to 70% and the temperature range from -1.1 to 24 °C in the heating run. The SAXS curves explored the self-assembly processes and hexagonal phase of the IL apparent sol. The saturated aliphatic ionic liquid in water assemble less tightly compared with aromatic ionic liquid based on imidazolium in water, which is due to the absence of aromatic package effect.

Thermal behaviors and transitions of wood detected by temperature-modulated differential scanning calorimetry

The thermal properties and transitions of solid and ground wood samples conditioned at different humidity conditions were investigated by temperature-modulated differential scanning calorimetry. A time-dependent transition was detected as an endothermic peak in the total and non-reversing heat flows and as a step change in the reversing heat flow during the first heating run of samples with moisture contents above 5 %, but it disappeared in the second heating run. These different thermal behaviors indicate that the effect of heat and moisture on the thermal properties of wood is history dependent. This step change in the reversing heat flow is considered to be a glass transition of moist wood. Other relaxation processes (e.g., enthalpy relaxation) occur simultaneously with this glass transition. The temperature ranges of the transition and the relaxation decreased drastically as the moisture content increased up to 11 %, while they remained almost constant at higher moisture contents. In addition, the transitions of the ground wood occurred at lower temperatures than those of the solid wood at similar moisture contents. Kissinger plots revealed that the apparent activation energy for the glass transition of the solid wood with a moisture content of 11 % was about 600 kJ/mol, whereas that of the ground wood was 220 kJ/mol.

Rock magnetic properties of fault rocks from the rupture of the 2008 Wenchuan earthquake, China and their implications: Preliminary results from the Zhaojiagou outcrop, Beichuan County (Sichuan)

Rock magnetic measurements were conducted on fault rocks from the Zhaojiagou outcrop at Leigu Town, Beichuan County, Sichuan Province (China), located on the Yingxiu–Beichuan Fault, the main fault ruptured in the 2008 Wenchuan Ms 8.0 earthquake. Hysteresis measurements indicate that fault rocks contain very low concentrations of ferrimagnetic minerals, and their magnetic behavior is dominated by para-/diamagnetic components. Temperature-dependent magnetic susceptibility increased significantly above 400°C in the heating run. Magnetic behavior reveals the presence of siderite, lepidocrocite, chlorite and smectite as the possible major Fe-bearing minerals in fault rocks. Their thermal decomposition to ferrimagnetic minerals (e.g., magnetite and/or maghemite) could be responsible for the high magnetic susceptibility during the thermal treatment. A kinetic model analysis indicates that frictional heating could increase the temperature within the fault zone up to 320–908°C at depth of 590m, and 335–952°C at depth of 618.3m, respectively, during the seismic slip of the Wenchuan earthquake, depending on shear stress. Such high temperatures are enough to drive thermal decomposition of Fe-bearing minerals in fault rocks (in particularly, in fault gouge), to form ferrimagnetic magnetite and/or maghemite. This is the most likely mechanism for the reported high magnetic susceptibility anomalies within the fault zone in the pilot hole of Wenchuan Earthquake Fault Scientific Drilling Project (WFSD-1).

High Temperature Mechanical Spectrum and Interstitial Oxygen in YBaCuFeO&lt;sub&gt;5+δ&lt;/sub&gt;

Double perovskite oxide YBaCuFeO5+δ samples (labeled as “as-prepared”) were sintered by a solid-state reaction technique. Mechanical spectra of as-prepared sample were measured under vacuum condition from room temperature up to 720K by the reed vibration method. In the first heating run, two internal friction peaks were observed around 380 and 620K (labeled as P1 and P2, respectively) in YBaCuFeO5+δ. In the subsequent cooling run, both of them disappeared and a small step-like decrease of the internal friction around 500K was found. This step-like change was reproduced in the following thermal cycles. Thermogravimetric analysis (TGA) was also performed in order to monitor the oxygen content of the sample. It showed that the interstitial oxygen concentration decreased in the first heating run. The interstitial oxygen relaxation is suggested to be the origin of P1 peak. In dielectric measurements, a dielectric loss peak appeared around the temperature of the P2 internal friction peak and the peak temperature was independent on the measuring frequency. It is expected that P2 is associated with some kind of transitions of the interstitial oxygen. Further mechanical loss measurement of the annealed sample and scanning electron microscopy characterizing the as-prepared and annealed samples, provided more information on the interstitial oxygen in YBaCuFeO5+δ samples.

Nd&lt;sub&gt;60&lt;/sub&gt;Fe&lt;sub&gt;30&lt;/sub&gt;Al&lt;sub&gt;10&lt;/sub&gt; Glass Forming Magnetic Alloys: A Mechanical Spectroscopy Study at the 300-560 K Temperature Range

The ferromagnetic amorphous phase in rapidly solidified Nd60Fe30Al10 glass forming alloys is investigated in melt spun ribbons (100 µm thick) and in chill cast cylinders (2 mm diameter). The amorphous resulting for these two different quenching rates were characterized by their room temperature hysteresis loops, magnetization and differential calorimetric measurements in the temperature range 300K-900K. The mechanical damping was explored in the 300-560 K temperature range, by measuring the internal friction and the shear modulus in a forced inverted pendulum operating in the frequency range 0.1-10Hz. Simultaneously, the electrical resistance of the samples was measured. The internal friction spectra of both, ribbons and a cylinder, exhibit a local maximum at about 500K, arising in a relaxation mechanism. After some thermal cycles the peak parameters stabilize reaching an apparent activation enthalpy of 1.5 eV and a limit relaxation time τ0 ≈ 0.4-2.5 . 10-17s. In both samples, the electrical resistance largely decreases during the first heating run to 560K and remains unchanged during subsequent thermal cycles. No changes in the elastic modulus or in the damping properties are detected at the Curie temperature of the alloys.

Development of bacterial cellulose nanowhiskers reinforced EVOH composites by electrospinning

AbstractIn the current study, hybrid electrospun ethylene vinyl alcohol (EVOH) fibers reinforced with bacterial cellulose nanowhiskers (BCNW) were developed and characterized. Additionally, electrospinning was suggested as a method for the incorporation of well‐dispersed BCNW into an EVOH matrix by melt compounding. With the aim of maximizing the BCNW's loading in the electrospun fibers, an optimized method was applied for generating fibers from solutions containing up to 40 wt % BCNW. As demonstrated by FTIR spectroscopy, it was possible to incorporate BCNW concentrations up to ∼ 24 wt %, although a complete incorporation of the nanofiller into the fibers was only achieved with solutions containing up to 20 wt % of the filler, DSC analyses suggested that the incorporation of the nanofiller reduced the crystallinity of the as‐obtained EVOH fibers and produced an increase in the glass transition temperature of these during the second heating run. Thermogravimetric analyses showed that even though EVOH protects the nanowhiskers from thermal degradation, the electrospun hybrid fibers present a relatively lower thermal stability than the pure EVOH fibers. FTIR analyses of the samples subjected to different thermal treatments confirmed that the stiffening effect observed by DSC only occurs after melting of the EVOH phase and is cooperative with a partial acid chemical development in the BCNW, which promotes strong chemical interactions between the polymeric matrix and the nanofiller. Finally, the hybrid electrospun fibers were incorporated into pure EVOH by melt compounding to produce composite films. This methodology showed higher stability and dispersion of the BCNW than direct addition of the freeze‐dried nanofiller to EVOH. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Formation of Intermediate Compound Li2B12H12 during the Dehydrogenation Process of the LiBH4–MgH2 System

Intermediate compound comprising [B12H12]2– anion formed in the dehydrogenation is regarded to be responsible for the degradation of reversibility of metal borohydrides, whereas little is known about the formation of Li2B12H12 in the LiBH4–MgH2 combined system. In this study, we investigated the dehydrogenation process of the LiBH4–MgH2 system in a heating run under different hydrogen pressures. Our experimental results demonstrated, for the first time, that Li2B12H12 was formed under hydrogen pressure ≤1.0 MPa, but not formed under 2.0 MPa. Moreover, the formation of Li2B12H12 was found to negatively depending on the hydrogen pressure, and also influence subsequent formation of MgB2: the more Li2B12H12 that formed, the less MgB2 obtained. These findings indicate that suppression of the formation of intermediate compound Li2B12H12, such as by using adequate hydrogen pressures (e.g., 2.0 MPa), is of great importance for further improvement of hydrogen storage properties of the LiBH4–MgH2 system.

Effect of counterion on the phase behaviour during lyophilization of indomethacin salt forms

This manuscript studies the effect of counterion on the phase behaviour during lyophilization of indomethacin salts. Salt forms of indomethacin namely, sodium, potassium, rubidium and cesium were prepared in situ and analyzed by modulated differential scanning calorimetry (MDSC) for determination of the critical process parameter for lyophilization. At a cooling rate of 17 °C/min, indomethacin salts separated as amorphous form on freeze concentration. T g ′ of indomethacin salts followed the order: sodium (−35.36 °C) > potassium (−38.90 °C) > rubidium (−43.70 °C) > cesium (−47.84 °C) salt. T g ′ was followed by crystallization exotherm during the heating run for all salts, except indomethacin cesium. At slower cooling rates (0.5 and 1 °C/min), indomethacin sodium, potassium and rubidium crystallized in the cooling run, while indomethacin cesium remained amorphous. The differential crystallization behaviour of indomethacin salts was explained in terms of bulkiness of the counterion, molecular interactions and structural relaxation behaviour near T g ′ . The research work has implications in lyophilization processing as well as the stability and performance of final product.

Synthesis of grafted polysilsesquioxane by ring-opening polymerization of lactide and trimethylene carbonate

The polysilsesquioxane (PSQ) containing 3-aminopropyl and phenyl groups (APSQ) was prepared from the corresponding trimethoxysilanes by co-condensation under basic conditions. The amino groups on APSQ were used as the initiator species for the graft polymerization of 1,3-trimethylene carbonate (TMC) and L-(-)-lactide (LA). The ring-opening polymerization of TMC and LA in the presence of the catalytic 1-trimethylsilylimidazole proceeded effectively to afford the PSQ with poly(TMC) and/or poly(LA) as the graft chains. The grafted PSQ containing poly(LA) showed the heat durability as an advantage of the hybrid polymer. In differential scanning calorimetry analysis, the grafted random copolymer of TMC and LA showed no clear endotherm corresponding to melting point (Tm). For the poly(LA)-grafted PSQ, the peak indicating Tm was observed in the first heating run, but the corresponding peak was very small in the second run. The polysilsesquioxane containing 3-aminopropyl and phenyl groups was used as the macroinitiator for the graft polymerization of 1,3-trimethylene carbonate and L-(-)-lactide. The ring-opening polymerizations of the monomers by the use of 1-trimethylsilylimidaozle catalyst proceeded effectively to afford the grafted polysilsesquioxanes. In the obtained polysilsesquioxanes, the effects of polysiloxane main chain on the thermal properties of the grafted polymers were observed.

Specific heat and low-field magnetocaloric effect in A-site ordered PrBaMn2O6 manganite

The specific heat and magnetocaloric effect (MCE) of A-site ordered PrBaMn2O6 manganite have been studied. The anomalies caused by the ferromagnetic (FM) and antiferromagnetic (AFM) phase transitions are revealed in the specific heat curve. Direct and inverse MCE are observed at the Curie and Néel points correspondingly. A value of the inverse MCE in the heating run is smaller than in the cooling regime. We attribute this effect to the competition between FM and AFM interactions. A significant advantage of PrBaMn2O6 as a magnetocaloric material is an MCE spanning a broad range of temperature with a maximum at room temperature.

Brillouin Light Scattering from Thin Albumen of Chicken Egg

Chicken eggs are rich in high-quality proteins and several kinds of trace elements, and have been a very familiar nutriment for human beings since ancient times. Chicken egg white comprises two layers, namely, thin albumen and thick albumen, both surrounding the yolk within a shell. There are two types of thin albumen known as the outer and inner thin albumens. The physical properties of both types of albumen are essentially the same. Thin albumen from chicken egg, hereafter referred to as egg white (EW), gels at a gelation temperature TG of ca. 66 C. The gelation process and the rheological properties of EW have attracted the attention of biological and biochemical scientists, food scientists, and physicists. The gelation process of EW has been studied by the ultrasound pulse technique at 3MHz in the temperature range between 10 and 95 C. The velocity of a longitudinal sound wave (LSW) exhibits a broader peak with a maximum at approximately 66 C as temperature increases through the sol–gel transition. Brillouin light scattering (BLS) measurement is another powerful and convenient technique for studying thermally excited hypersonic sound waves in the GHz frequency region. By utilizing a (3+3)-pass Fabry– Perot interferometer (FPI), we expect to observe a BLS spectrum from EW even near TG. We purchased fresh Boris Brown eggs with a red shell laid within a day at a farmers market near our university just before each measurement. About 5ml of thin albumen or distilled water was transferred into a glass tube placed in a brass cell. The cell temperature was regulated up to 82 C within an accuracy of 0:1 C and monitored by an almel– chromel thermocouple. We repeated our BLS measurement six times only during a heating run. BLS spectra were probed using the 1⁄4 488 nm excitation from an Arþ laser in a single-cavity mode with an output power of 40mW. BLS spectra were obtained using a laboratory-built (3+3)-pass FPI. Since EW gradually becomes opalescent with increasing temperature above 50 C, we employed the 180 scattering geometry, which allows us to continue our BLS measurements up to 61 C. In order to determine the LSW velocity V and the refractive index n at 488 nm, we also adopted the 90A scattering geometry at 24 C. Figure 1 shows an example of the 180 and 90A BLS spectra of EW at 24 C. We performed a numerical convolution analysis of these BLS spectra by adopting the damped harmonic oscillator (DHO) function for the elastic response function Sðq; !Þ;

Development of electrospun EVOH fibres reinforced with bacterial cellulose nanowhiskers. Part I: Characterization and method optimization

In the present study, hybrid electrospun EVOH fibres reinforced with bacterial cellulose nanowhiskers (BCNW) were developed and characterized. The nanowhiskers, obtained by sulphuric acid digestion of native bacterial cellulose mats generated by Gluconacetobacter xylinum, were morphologically characterized by SEM and optical microscopy with polarized light and revealed a highly crystalline structure of nanofibrils aggregates. XRD analyses suggested a crystalline structure corresponding to the cellulose I allomorph. It was also confirmed by means of FT-IR spectroscopy that amorphous regions were preferentially digested by the acid treatment, whereas TGA analyses showed a decrease in the thermal stability of the nanowhiskers most likely due to incorporation of sulphate groups and the inherent acidity remaining in the filler even after extensive washing cycles. A method was developed for improving the incorporation of BCNW within the EVOH electrospun fibres, consisting on the addition of the BCNW in the form of a centrifuged precipitate, versus the most conventionally employed freeze-dried nanowhiskers. DSC analyses showed a significant increase in the glass transition temperature of the composites during the second heating run, which may be related to the acidic character of the nanofiller. Finally, sonication was seen to enhance interfacial interaction but to reduce the incorporation of the filler in the matrix in the case of the centrifuged material.

Free volume in imidazolium triflimide ([C3MIM][NTf2]) ionic liquid from positron lifetime: Amorphous, crystalline, and liquid states

Positron annihilation lifetime spectroscopy (PALS) is used to study the ionic liquid 1-methyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide [C(3)MIM][NTf(2)] in the temperature range between 150 and 320 K. The positron decay spectra are analyzed using the routine LifeTime-9.0 and the size distribution of local free volumes (subnanometer-size holes) is calculated. This distribution is in good agreement with Fürth's classical hole theory of liquids when taking into account Fürth's hole coalescence hypothesis. During cooling, the liquid sample remains in a supercooled, amorphous state and shows the glass transition in the ortho-positronium (o-Ps) lifetime at 187 K. The mean hole volume varies between 70 Å(3) at 150 K and 250 Å(3) at 265-300 K. From a comparison with the macroscopic volume, the hole density is estimated to be constant at 0.20×10(21) g(-1) corresponding to 0.30 nm(-3) at 265 K. The hole free volume fraction varies from 0.023 at 185 K to 0.073 at T(m)+12 K=265 K and can be estimated to be 0.17 at 430 K. It is shown that the viscosity follows perfectly the Cohen-Turnbull free volume theory when using the free volume determined here. The heating run clearly shows crystallization at 200 K by an abrupt decrease in the mean <τ(3)> and standard deviation σ(3) of the o-Ps lifetime distribution and an increase in the o-Ps intensity I(3). The parameters of the second lifetime component <τ(2)> and σ(2) behave parallel to the o-Ps parameters, which also shows the positron's (e(+)) response to structural changes. During melting at 253 K, all lifetime parameters recover to the initial values of the liquid. An abrupt decrease in I(3) is attributed to the solvation of e(-) and e(+) particles. Different possible interpretations of the o-Ps lifetime in the crystalline state are briefly discussed.

An Original Polymorph Sequence in the High-Temperature Evolution of the Perovskite Pb2TmSbO6

The synthesis, crystal structure, and dielectric properties of the novel double perovskite Pb(2)TmSbO(6) are described. The room-temperature crystal structure was determined by ab initio procedures from neutron powder diffraction (NPD) and synchrotron X-ray powder diffraction (SXRPD) data in the monoclinic C2/c (No. 15) space group. This double perovskite contains a completely ordered array of alternating TmO(6) and SbO(6) octahedra sharing corners, tilted in antiphase along the three pseudocubic axes, with an a(-)b(-)b(-) tilting scheme, which is very unusual in the crystallochemistry of perovskites. The lead atoms occupy a highly asymmetric void with 8-fold coordination due to the stereoactivity of the Pb(2+) lone electron pair. This compound presents three successive phase transitions in a narrow temperature range (at T1 = 385 K, T2 = 444 K, and T3 = 460 K in the heating run) as shown by differential scanning calorimetry (DSC) data. The crystal structure and temperature-dependent NPD follow the space-group sequence C2/c → P2(1)/n → R3 → Fm3m. This is a novel polymorph succession in the high-temperature evolution of perovskite-type oxides. The Tm/Sb long-range ordering is preserved across the consecutive phase transitions. Dielectric permittivity measurements indicate the presence of a paraelectric/antiferroelectric transition (associated with the last structural transition), as suggested by the negative Curie temperature obtained from the Curie-Weiss fit of the reciprocal permittivity.

Effect of water content on electrical conductivity of fish skin collagen

The increased interest in fish skin collagen results from the risk of BSE disease and the production of native collagen by the acidic hydration method. As a material, FSC derived by the novel acidic hydration method was used. The bovine Achilles tendon (BAT) collagen type I was applied as a control material. Measurements were carried out at the temperature range 2980 K–510 K. Each sample was heated twice. During the first heating run for FSC, to 380 K, the maximum was localized at 343 K, at electrical conductivity of 7 · 10 −6 S/m. In the second heating run to 510 K, the maximum was observed at 443 K for FSC, and at 487 K for BAT collagen. The peaks revealed in the temperature range 320–350 K were related to the free water and bound water release, alike for FSC and BAT collagen. The process of water removal for both types of collagen takes place in similar temperature ranges.