High Purity Type Research Articles

Clinical Efficacy of Type I Collagen Skin Substitutes Versus Human Amnion/Chorion in Treating Diabetic Foot Ulcers Using 55 Patient Randomized Controlled Independent Two Trials, One in India and the Other in the USA

Abstract The purpose of this study is to compare whether the results of two separate studies simulates each other. As one would expect, the results are duplicative of each other that’s what we are planning to discuss in this research article. In a nutshell, the first study was conducted by Professional Education & Research Institute (PERI) at 9825 Kenwood Road, Suite 100, Blue Ash, OH 45242, USA which was managed by prestigious Dr. Charles M. Zelen, DPM who has over 20 years of clinical, academic, and industry experience in extremities, wound care, and biologic development programs. Over 22 Clinical Study publications have been published in reputed peer-reviewed journals. Another similar study was conducted by a distinguished plastic surgeon with immense experience in conducting randomized controlled clinical studies by name Dr. Naveen Narayan, MS, MCh (Plastic Surgery) at Adichunchanagiri Institute of Medical Sciences (AIMS), B G Nagara, Karnataka, India. To add to his credentials, he has 57 Clinical Study publications in respected journals with peer review. Both studies were registered on clinicaltrials.gov where one study was enrolled with 28 patients (NCT06470087) and the other study had a total no. of 27 patients (NCT06557122). It was intended to enroll 28 patients for each study. However, in the USA study, the Contact Research Organization (CRO) was able to recruit only 27 patients for the study in order to start the study on time. The first study of 28 patients were randomized into 2 groups of 14 patients each. The other study randomized into 2 groups of 12 patients each with exclusion of 3 patients who were rejected for the study due to their non-compliance with the approved protocol. Among the tested skin substitutes, one group consisted of standard of care (SOC) with High-Purity Type I Collagen-based Skin Substitute (HPTC) and the other group is the standard of care (SOC) with Dehydrated Human Amnion/Chorion Membrane (dHACM) in the treatment of Diabetic Foot Ulcers (DFUs). Each group was followed for 4 weeks of treatment as described in the methods section. The wound healing outcomes were evaluated on days 7, 10, 14, 17, 21, and 28. Both the study results were compared. The results from both India (AIMS) and the USA (PERI) studies showed that the HPTC group achieved significantly better healing outcomes compared to the dHACM group. Over the 28-day study period, HPTC demonstrated a healing recovery rate of 62%, while dHACM showed a recovery rate of 38%. These findings highlight that HPTC not only facilitated faster healing but also more complete wound closure, suggesting it as a potentially more effective treatment for managing chronic diabetic foot ulcers and reducing the risk of long-term complications. Even though they were conducted independently and separated continents apart, the clinical outcomes for both the studies were statistically significant proving the clinical efficacy of High-Purity Type I Collagen-based Skin Substitute (HPTC) was much higher than the other group, Dehydrated Human Amnion/Chorion Membrane (dHACM).

Direct observation of vortices in an electron fluid.

Vortices are the hallmarks of hydrodynamic flow. Strongly interacting electrons in ultrapure conductors can display signatures of hydrodynamic behaviour, including negative non-local resistance1-4, higher-than-ballistic conduction5-7, Poiseuille flow in narrow channels8-10 and violation of the Wiedemann-Franz law11. Here we provide a visualization of whirlpools in an electron fluid. By using a nanoscale scanning superconducting quantum interference device on a tip12, we image the current distribution in a circular chamber connected through a small aperture to a current-carrying strip in the high-purity type II Weyl semimetal WTe2. In this geometry, the Gurzhi momentum diffusion length and the size of the aperture determine the vortex stability phase diagram. We find that vortices are present for only small apertures, whereas the flow is laminar (non-vortical) for larger apertures. Near the vortical-to-laminar transition, we observe the single vortex in the chamber splitting into two vortices; this behaviour is expected only in the hydrodynamic regime and is not anticipated for ballistic transport. These findings suggest a new mechanism of hydrodynamic flow in thin pure crystals such that the spatial diffusion of electron momenta is enabled by small-angle scattering at the surfaces instead of the routinely invoked electron-electron scattering, which becomes extremely weak at low temperatures. This surface-induced para-hydrodynamics, which mimics many aspects of conventional hydrodynamics including vortices, opens new possibilities for exploring and using electron fluidics in high-mobility electron systems.

Long dephasing time of NV center spins in diamond layers formed by hot ion implantation and high pressure high temperature annealing

Thin nitrogen doped layers with ~1 ppm NV center ensembles were created by the hydrogen implantation of type Ib or hot nitrogen implantation in the high purity type IIa and IIb high pressure high temperature-grown (HPHT) diamond and followed HPHT treatment up to 1500 °C at 7 GPa. The dephasing time T2* = 0.4–0.9 μs was obtained even for the implanted nitrogen content of ~100 ppm. The data evidence the absence of other spin active defects besides the implanted nitrogen atoms in neutral states, determined this decoherence.

The Effect of CuCl2 on Pitting Corrosion of the Extra High Purity Type 316 Stainless Steel

The effects of Cu addition on corrosion behavior of stainless steels are known to be controversy1,2, which depends on the corrosion environment or the amount of alloying Cu. In chloride environment, alloying Cu is known to prohibit the growth of pitting corrosion. The dissolved Cu2+ acted as an inhibiter inside the pits3. On the other hand, there are few studies about the effect of Cu2+ ions in the solution on the pitting corrosion of the stainless steels. Since the commercially made stainless steels commonly contains more than 0.1 mass% Cu, the Cu2+ ions which was dissolved from stainless steels made it difficult to evaluate the effect of Cu2+ ions on the pitting behavior of the stainless steels. Although the amount of dissolved Cu2+ was quite few, the Cu2+ concentration inside the pits was expected to be much higher than the solution bulk because the pitting corrosion was very localized phenomenon. Therefore, Cu2+ in the solution and dissolved Cu2+ should be analyzed separately. To clarify the effect of Cu2+ in the solution on the pitting corrosion of the stainless steels, the amount of alloying Cu is needed to be low enough not to affect the corrosion morphology. In this study, extra high purity Type 316 stainless steel (316EHP) was used as specimen. The Cu content of the specimen was 6.8 × 10-4 mass %. The specimens were heat-treated at 1373 K for 3.6 ks and then quenched in water. The surfaces of the specimens were polished down to 1 µm with a diamond paste. After that, specimens were ultrasonically cleaned in ethanol. Electrochemical measurements were conducted in deaerated 0.1 M NaCl or 0.098 M NaCl-1 mM CuCl2. Except the electrode area (ca. 10 × 10 mm), the surfaces of the specimens were insulated by an epoxy resin. The potential scan rate was 3.33 × 10-4 V s-1 (20 mV min-1). The reference electrode was an Ag/AgCl (Sat. KCl) electrode. All the potentials cited in this work refer to the Ag/AgCl (Sat. KCl) electrode. After the electrochemical measurements, the surfaces were analyzed by SEM/EDS and XPS. The inclusions of the specimen were characterized by SEM/EDS. The inclusions were identified as a Cr-oxide. The anodic polarization curves were measured in deaerated 0.1 M NaCl or 0.098 M NaCl-1 mM CuCl2. Although no pitting was observed in 0.1 M NaCl, pitting was occurred in 0.098 M NaCl-1 mM CuCl2. In both solutions, the dissolution of inclusions was not confirmed. Therefore, the inclusions were not thought to be the initiation site of pitting. This indicates that the pitting potential of 316EHP was decreased by Cu2+ in the solution. Cu2+ ions were thought to act as an accelerator of pitting corrosion. To analyze the effect of Cu2+ ions on the forming passivation film, potentiostatic polarization measurements at 0.4 V were carried out in 0.098 M NaCl-1 mM CuCl2. As a result, existence of a Cu signal on the surface was confirmed by XPS although it was not detected by SEM/EDS. This result indicatets that the few amounts of Cu compound was deposited on the surface in passive region of the 316 EHP.

Self-assembly study of type I collagen extracted from male Wistar Hannover rat tail tendons

BackgroundCollagen, the most abundant protein in the animal kingdom, represents a promising biomaterial for regenerative medicine applications due to its structural diversity and self-assembling complexity. Despite collagen’s widely known structural and functional features, the thermodynamics behind its fibrillogenic self-assembling process is still to be fully understood. In this work we report on a series of spectroscopic, mechanical, morphological and thermodynamic characterizations of high purity type I collagen (with a D-pattern of 65 nm) extracted from Wistar Hannover rat tail. Our herein reported results can be of help to elucidate differences in self-assembly states of proteins using ITC to improve the design of energy responsive and dynamic materials for applications in tissue engineering and regenerative medicine.MethodsHerein we report the systematic study on the self-assembling fibrillogenesis mechanism of type I collagen, we provide morphological and thermodynamic evidence associated to different self-assembly events using ITC titrations. We provide thorough characterization of the effect of pH, effect of salts and protein conformation on self-assembled collagen samples via several complementary biophysical techniques, including circular dichroism (CD), Fourier Transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), atomic force microscopy (AFM), scanning electron microscopy (SEM), dynamic mechanical thermal analysis (DMTA) and thermogravimetric analysis (TGA).ResultsEmphasis was made on the use of isothermal titration calorimetry (ITC) for the thermodynamic monitoring of fibrillogenesis stages of the protein. An overall self-assembly enthalpy value of 3.27 ± 0.85 J/mol was found. Different stages of the self-assembly mechanism were identified, initial stages take place at pH values lower than the protein isoelectric point (pI), however, higher energy release events were recorded at collagen’s pI. Denatured collagen employed as a control exhibited higher energy absorption at its pI, suggesting different energy exchange mechanisms as a consequence of different aggregation routes.Graphical abstract

Physicochemical and Reactive Oxygen Species Scavenging Properties of Collagen and Collagen Hydrolysates from Farmed Globefish (Fugu rubripes) Bone

ABSTRACTGlobefish (Fugu rubripes) bone collagen (GBC) was isolated and characterized. Electrophoresis and Fourier transform infrared (FTIR) spectra indicated that GBC was high-purity type I collagen with an intact triple-helical structure. Amino acid analysis revealed that GBC contained higher glycine content (364 residues/1,000 residues) than that of other fishery bones, and the imino acid content was 189 residues/1,000 residues. The denaturation temperature (Td) of GBC was 27.1°C. GBC displayed a rapid fibril-forming rate and well-defined fibril morphology in vitro. Globefish bone collagen hydrolysates (GBCH) were optimized by neutral protease through response surface methodology (RSM) with the highest hydroxyl radical (•OH) scavenging capacity. The optimal hydrolysis condition was a reaction temperature of 48.4°C, time of 120 min, and enzyme/substrate ratio of 2520 U/g. Three fractions were collected by ultrafiltration, and the fraction GBCH-III (Mw<1 kDa) possessed the strongest •OH scavenging ability. Reactive oxygen species (ROS) scavenging capacities were evaluated with two model systems: •OH and nitric oxide (NO•). The ROS scavenging capacities increased in a dose-dependent manner. GBCH-III proved to be a more effective •OH scavenger than reduced glutathione (GSH). These findings demonstrated that GBC and GBCH have potential as an alternative source of collagen-derived materials for use in pharmaceutical, nutraceutical, and cosmetic industries.

Permeative Amine Introduction for Very Weak Acid Detection in Ion Chromatography.

A permeative amine introduction device (PAID) is placed after a conventional KOH eluent-suppressed conductometric anion chromatography (SCAC) system. The PAID converts the suppressed eluites from the acid form to the corresponding ammonium salt (NR2H + HX → NR2H2(+) + X(-)) and allows very weak acids HX (pKa ≥ 7.0) that cannot normally be detected by SCAC to be measured by a second conductivity detector following the PAID. Permeative reagent introduction is dilutionless, can be operated without pumps, and provides good mixing (baseline noise 0.8 nS/cm for 27 μM diethylamine) with low band dispersion (as small as 30 μL). Diethylamine (DEA) was chosen as the amine source due to its low pKb value (3.0), high vapor pressure, low toxicity, and low odor. The eluites are thus detected against a low diethylammonium hydroxide (DEAOH) background (5-31 μS/cm) as negative peaks because the equivalent conductance of OH(-) is greater than that of X(-). Reducing the background DEA concentration enhances the detectability of traces of weak acids. Lower background [DEA] will limit the maximum concentration of analyte acids that can be determined; a general concept of peak width measurement at a fixed height is proposed as a solution. Trace impurities formed during electrodialytic suppression play a role in background noise; for the first time, we look at the nature of such impurities. The appearance of silicate in a sample put in a glass container as a function of pH can be readily followed. The maximum silica level in high purity type 1 water is 50 nM (1.40 μg/L Si), which is a measurement challenge in particular. A large injection volume (1 mL) permits detection limits of 21 nM silicate, 3 nM taurine, 3 nM sulfide, and 13 nM cyanide.

Simultaneous preparation and characterization of three high-purity type B fumonisins from maize culture

A reliable and large-scale preparative method was developed for the simultaneous preparation of high-purity fumonisin B1(FB1), fumonisin B2(FB2) and fumonisin B3(FB3) from maize culture inoculated withFusarium moniliformein this study.

超高純度304，316系ステンレス鋼の高温割れ感受性評価

超高純度304，316系ステンレス鋼の高温割れ感受性評価

Quantitative influence of minor and impurity elements on solidification cracking susceptibility of extra high purity type 310 stainless steel

To evaluate the influence of minor and impurity elements on the solidification cracking susceptibility in austenitic stainless steel welds, the transverse Varestraint test was conducted using several extra high purity type 310 stainless steels with different amounts of C, Mn, P and S. The characteristic influence on solidification cracking could be expressed by the ratio of P/S/C≈1∶1·3∶0·56, while Mn affected solidification cracking to a negligible extent. A theoretical approach revealed that the reduced solidification cracking susceptibility with decreasing C, P and S contents could be attributed to the suppression of solidification segregation.

Dynamics of negatively charged divacancies in neutron irradiated type Ib diamond

Thermal neutron irradiation of synthetic type Ib diamond, followed by annealing, results in a number of paramagnetic point defect centers. One of these is the composite defect designated W29. Previous EPR measurements have shown that the W29 center (S=3/2) is a charged divacancy [VV]− with spin Hamiltonian parameters similar to those of the R4/W6 neutral divacancy center [VV]0 (S=1) found in irradiated high purity type IIa diamond. The present EPR linewidth and spin-lattice relaxation rate measurements, made as a function of temperature on the W29 center, show that an Orbach two-phonon process, with a gap of ~20meV, plays a dominant role in determining the relaxation behavior above 20K. Below 20K a direct single phonon process provides the spin-lattice relaxation mechanism and the relaxation times become long, of the order of milliseconds. The linewidth behavior with temperature is accounted for in terms of changes in the spin dynamics.

超高純度310系ステンレス鋼の高温割れ感受性に及ぼす微量・不純物元素の定量的寄与

超高純度310系ステンレス鋼の高温割れ感受性に及ぼす微量・不純物元素の定量的寄与

純度の異なる中炭素鋼の疲労寿命への水素添加の影響

Fatigue tests were conducted on two kinds of normalized S45C commercial steel bars that are of different purity. Amount and state of hydrogen are determined by thermal desorption spectroscopy (TDS) after cathodic charging. Effects of impurity elements and non-metallic inclusions have been discussed.The fatigue life is less damaged in high purity type S45C (S45C/hpt) with same amount of hydrogen pre-charging, although the non-charged S45C steels exhibits almost same fatigue lives.The TDS main peak around 335K is lower in S45C/hpt and hydrogen pick-up is smaller. This could be explained by the smaller amount of MnS. Though, it is only the subsidiary reason for the susceptibility.The S45C/hpt being sufficiently de-oxidized, the Al2O3 inclusions are reduced in size and quantity. Furthermore, they are wrapped by MnS. The comparative S45C contains silicate inclusions. Both are elongated and cohesive to ferrite matrix; not resulting in the internal failure with hydrogen pre-charging.Phosphorus would enhance hydrogen trapping along grain boundary and promote the fracture along it. Grain boundary facet being not found for both steels, it would not deal so much with the present hydrogen susceptibility.With S45C/hpt, soluble nitrogen atoms are reduced by sufficient Al addition. This may lead to the late dislocation cell formation and responsible to the cyclic softening that lasts long at the beginning of strain cycling.This cyclic softening acts to reduce the dislocation density in S45C/hpt. It would make the steel insensitive to hydrogen substantially through decreased hydrogen concentration.

Improvement of Pitting Corrosion Resistance of Type 316L Stainless Steel by Potentiostatic Removal of Surface MnS Inclusions

The beneficial effect of the removal of MnS inclusions on the pitting of stainless steels has been demonstrated in two ways. (1) High-purity Type 316L stainless steel with no inclusions was used as a specimen in the measurement of anodic polarization curves in 0.5 M NaCl and (2) commercial Type 316L stainless steel with MnS and slag-related inclusions was first polarized at different potentials for 30 min in 1 M Na2SO4of pH 3 and then anodic polarization measurements were taken in 0.5 M NaCl. Pitting did not occur in the passive or transpassive region of the high-purity steel. The polarization treatment dissolved MnS and some oxide inclusions (CaO and SiO2) on the surface of the commercial steel. An increase in pitting potential of the commercial steel was noted after treatment at potentials above 0.2 V. At the same time, the number of current spikes due to metastable pits decreased significantly. These results are more likely due to the beneficial effect of removing MnS inclusions from the steel surface rather than the modification effect of the chemical composition of passive films on the surface.

Optical properties of single crystal diamond microfilms fabricated by ion implantation and lift-off processing

We report the fabrication and optical characterisation of ~1 μm thick films of single crystal diamond prepared by an ion implantation and lift-off process. A comparison is made between type 1b material grown by high-temperature high-pressure and high purity type 2a material grown by chemical vapour deposition. Our results show that the fabrication process does not suppress strong emission from nitrogen-vacancy colour centres in the type 1b material. The 1332 cm − 1 Raman line normally prominent in the CVD material is found to be strongly suppressed. A 20 nm thick damaged layer of sp 3 carbon is identified on the underside of the films that indicates residual damage from the implantation process. These results are of significance for the fabrication of devices in diamond in which colour centres couple to discrete optical modes.

SCC susceptibility of cold-worked stainless steel with minor element additions

To examine the effects of minor elements on stress corrosion cracking (SCC) susceptibility of low carbon stainless steels with a work hardened layer, a high purity type 304 stainless steel was fabricated and minor elements, Si, S, P, C or Ti, were added. A work hardened layer was introduced by shaving on the surface of stainless steels. The specimens were exposed to a boiling 42% MgCl2 solution for 20h and the number and the length of initiated cracks were examined. SCC susceptibility of the specimen with P was the highest and that of the specimen with C was the lowest in all specimens. By magnetic force microscope examination, a magnetic phase expected to be a martensitic phase was detected near the surface. Since corrosion resistance of martensite is lower than that of austenite, the minor elements additions would affect SCC susceptibility through the amount of the transformed martensite.

Hot cracking behaviour and susceptibility of extra high purity type 310 stainless steels

Recent progress in the refining technology has enabled the production of highly pure commercial stainless steels. The hot cracking behaviour of these stainless steels was investigated with respect to type 310 stainless steel. For comparison, four types of 310 stainless steels with various amounts of minor and impurity elements such as C, P and S were used. The purity of type 310 stainless steels used was enhanced in the order of type 310<type 310S<type 310ULC<type 310EHP steels. The hot cracking susceptibility was evaluated by the transverse Varestraint test. Two types of hot cracks occurred in these steels by Varestraint test; solidification and ductility-dip cracks. The solidification cracking susceptibility was significantly reduced as the amount of C, P and S decreased, and that in type 310EHP steel reached a level so low that solidification cracking did not occur in practical welding. On the other hand, the ductility-dip cracking susceptibility adversely increased as the purity of the steels was enhanced. However, the ductility-dip cracking susceptibility of type 310EHP steel was sufficiently low as not to yield ductility-dip cracking in practical multipass welding. The experimental and numerical analyses on the solidification brittle temperature range have revealed that the reduced solidification cracking susceptibility upon decreasing the amount of C, P and S in stainless steel can be attributed to the reduced BTR due to the suppression of minor and impurity elements, such as C, P and S, in the finally solidified liquid film between the dendrite.

HPHT growth and x-ray characterization of high-quality type IIa diamond

The trend in synchrotron radiation (x-rays) is towards higher brilliance. This may lead to avery high power density, of the order of hundreds of watts per square millimetre at the x-rayoptical elements. These elements are, typically, windows, polarizers, filters andmonochromators. The preferred material for Bragg diffracting optical elements at present issilicon, which can be grown to a very high crystal perfection and workable sizeas well as rather easily processed to the required surface quality. This allowsx-ray optical elements to be built with a sufficient degree of lattice perfectionand crystal processing that they may preserve transversal coherence in the x-raybeam. This is important for the new techniques which include phase-sensitiveimaging experiments like holo-tomography, x-ray photon correlation spectroscopy,coherent diffraction imaging and nanofocusing. Diamond has a lower absorptioncoefficient than silicon, a better thermal conductivity and lower thermal expansioncoefficient which would make it the preferred material if the crystal perfection (bulkand surface) could be improved. Synthetic HPHT-grown (high pressure, hightemperature) type Ib material can readily be produced in the necessary sizes of 4–8 mmsquare and with a nitrogen content of typically a few hundred parts per million.This material has applications in the less demanding roles such as phase plates:however, in a coherence-preserving beamline, where all elements must be of thesame high quality, its quality is far from sufficient. Advances in HPHT synthesismethods have allowed the growth of type IIa diamond crystals of the same sizeas type Ib, but with substantially lower nitrogen content. Characterization ofthis high purity type IIa material has been carried out with the result that thecrystalline (bulk) perfection of some of the HPHT-grown materials is approaching thequality required for the more demanding applications such as imaging applicationsand imaging applications with coherence preservation. The targets for furtherdevelopment of the type IIa diamond are size, crystal perfection, as measuredby the techniques of white beam and monochromatic x-ray diffraction imaging(historically called x-ray topography), and also surface quality. Diamond platesextracted from the cubic growth sector furthest from the seed of the new lowstrain material produces no measurable broadening of the x-ray rocking curvewidth. One measures essentially the crystal reflectivity as defined by the intrinsicreflectivity curve (Darwin curve) width of a perfect crystal. In these cases themore sensitive technique of plane wave topography has been used to establisha local upper limit of the strain at the level of an ‘effective misorientation’ of10−7 rad.

Effects of silicon, carbon and molybdenum additions on IASCC of neutron irradiated austenitic stainless steels

To study the effects of minor elements on irradiation assisted stress corrosion cracking (IASCC), high purity type 304 and 316 stainless steels (SSs) were fabricated and minor elements, Si or C were added. After neutron irradiation to 3.5 × 10 25 n/m 2 ( E>1 MeV), slow strain rate tests (SSRTs) of irradiated specimens were conducted in oxygenated high purity water at 561 K. Specimen fractured surfaces were examined using a scanning electron microscope (SEM) after the SSRTs. The fraction of intergranular stress corrosion cracking (IGSCC) on the fractured surface after the SSRTs increased with neutron fluence. In high purity SS with added C, the fraction of IGSCC was the smallest in the all SSs, although irradiation hardening level was the largest of all the SSs. Addition of C suppressed the susceptibility to IGSCC.

Vacancy diffusion and trapping in electron-irradiated type IaA diamonds

Abstract It has been reported that larger densities of vacancies are formed during electron irradiation of type IaA diamonds than in the case of high purity type IIa diamonds, and that a fraction of these vacancies f decays slower than the rest during annealing [Phys. Rev. B 46 (1992) 13157]. In this paper the latter, experimentally observed, double-decay equation is derived from basic physical postulates. It is assumed that the strain fields, surrounding the A-centers, attract vacancies towards these defects and repel interstitial atoms; in this way reducing the correlated recombinations that would have occurred without such forces being present, and, thus, causing an increase in vacancy density. These forces have been modeled in terms of ‘capture-volumes’ V surrounding the A-centers. Once within such a volume, a vacancy cannot escape and must finally end up at the A-center. The increase in the fast fraction with annealing temperature that had been ascribed to ‘uphill’ diffusion is modeled in terms of smaller ‘catch-volumes’ that also surround the A-centers. Once a vacancy enters the latter, it combines with the A-center to form an H3-center, and this process requires the scaling of a larger activation barrier than in the case of vacancy diffusion. The previously published experimental results are well modeled for capture-volumes V that, when added together, occupy less than 10% of the total volume of the diamond, and for an initial fraction of vacancies larger than 90% within them. This means that outside of these volumes the density of vacancies is far less than would have been the case in a pure diamond that do not contain A-centers. It is, accordingly, postulated that the interstitial atoms that form within the volumes V are, at some stage, ejected from these volumes by strain-assisted diffusion. This increase in density of the interstitials outside of the volumes, enhances vacancy annihilation when the annealing temperature is reached at which these interactions occur.