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Continuous specimen cooling during slicing and thickness measurement contributes to improved accuracy in image analysis of pathologic specimens.

Sections were prepared from a paraffin-only block and formalin-fixed paraffin-embedded (FFPE) blocks containing fish sausage and human liver specimens. The ST was compared between the sections prepared with cooling using an ice pack (IP) or a continuous cooling device (CCD) paired with a sliding microtome set at an ST of 4 µm. The sections were stained with eosin or aniline blue, and the association between the percent area of positive staining and ST was determined using computer-aided analysis of images captured with a whole slide scanner. The average STs of the paraffin-only block sections measured by four practitioners were 5.01-5.41 and 4.09-4.33 µm in samples prepared using an IP and a CCD, respectively. Therefore, subsequent analyses included sections prepared using the CCD. The ST of the tissue surface was significantly thinner than that of the paraffin surrounding the tissue section. Furthermore, the percent areas of positive staining for eosin and aniline blue were significantly correlated with ST in both the fish sausage and liver sections. The analysis of the ST and percent area of positive staining in 60 sections of the same block, which were categorized into quantiles based on ST, revealed a significant difference in the percent area of positive staining between the thicker and thinner sections. Specimen sectioning should be performed with a CCD, ST should be measured before the staining of pathologic specimens prepared for quantitative analysis, and histologic examination should be performed using specimens with uniform ST.

Spectroscopic properties and numerical analysis of novel erbium doped multi-component tellurite glasses

In this paper, Er3+ doped TeO2-ZnF2-BaF2-KF-Ta2O5 tellurite glasses with low hydroxyl content (∼0.03 × 10−19 cm−3) were investigated employing both glass composition and glass melting process optimization. The Raman spectra and physical properties were characterized to analyze the structure of the glasses. Under the pumping of 980 nm LD laser, intense up-conversion fluorescence at 1.5 and 2.7 μm of samples and their lifetimes were detected and analyzed, and the related transition mechanisms with gradient-varying Er3+ doping concentrations were discussed. The maximum absorption and emission cross section at 2.7 μm was calculated to be 6.4 × 10−21 cm2 and 6.8 × 10−21 cm2, correspondingly, which were higher than those of traditional tellurite glasses. Using the calculated and measured spectroscopic parameters of bulk tellurite glass, a dual-wavelength pumping model was established to verify the feasibility of mid-infrared laser output in similar tellurite glass fiber. Experimental results support the assertion that the Er3+ doped tellurite glasses hold promise as a candidate laser gain medium for mid-infrared fiber laser systems.

EFFECT OF HOT ROLLING AND SOLUTION TREATMENT ON THE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF FE-MN-SI-CR-NI SHAPE MEMORY ALLOY

Fe-14Mn-4Si-8Ni-11Cr SMA (shape memory alloy) was designed as a smart material because of its specific properties, which can memorize the original shape, so it has the potential to dampen vibration in seismic structures. Memory effect is triggered by SIM (stress-induced martensitic) transformation from γ-austenite to ε-martensite (hexagonal close-packed / HCP) structure, and it is recovered by heating after unloading. This study investigated the effect of hot rolling and solution treatment on the microstructure and its relationship with hardness and SME (shape memory effect) properties. The as cast of Fe-14Mn-4Si-8Ni-11Cr was hot rolled (900 and 1000 ℃) and solution treated (1000 and 1100 ℃). After the thermomechanical process, all microstructures consist of γ-FCC (face-centered cubic), the annealing twins, and a fine band of ε-martensite. The grain size of the γ-phase is 29.43, 41.96, 42.44, and 45.57 μm for samples B, C, D, and E, respectively. The higher the temperature of hot rolling and solution treatment applied, the larger the grain size obtained, indirectly reducing the hardness to 299.93 BHN and 286.52 BHN for samples D and E. The coarsened austenite grain, a lower number of annealing twins, and the pre-existing line band of ε-martensite are favorable to obtain the enormous recovery strain, up to 8.26% for sample E.

Simultaneous determination of electrical conductivity and thickness of nonmagnetic metallic foils using two-sided multifrequency eddy current techniques.

In this paper, we describe a simple method for performing multifrequency eddy current characterization of free-standing uniform-thickness metallic foils using a forked inductive coil arrangement. The method involves measuring the mutual inductance between two coils when a foil is present between the coils, and when it is not present; the ratio of these mutual inductances is compared with an analytical solution, and foil conductivity, thickness, and sheet resistance are simultaneously estimated using numerical inversion and least-squares fitting. This method was used to characterize 34 non-ferrous metallic samples with thicknesses between 50 and 640 μm and with conductivities between 0.8 × 107 and 5.8 × 107 S/m. The estimated thicknesses from eddy current characterization agreed well with those measured using confocal optical techniques; the two approaches agreed to within 1 μm for samples that were thinner than 200 μm, and to within 0.5% for samples that had a thickness of 200 μm or greater. The estimated conductivities from eddy current characterization were in close agreement with expected values, given knowledge of the materials used. A particular strength of this approach is that the instrumentation needed is broadly available in research and development laboratories and the associated fixturing is easy to manufacture and assemble. A calibration procedure is described that can be used to reduce errors from geometric uncertainties. This calibration requires a sample that has only a known conductivity or thickness; both do not need to be known. The method described herein is likely extensible to conductivities and thickness well outside the ranges measured as part of this work.

Predicting oxidation damage of ultra high-temperature carbide ceramics in extreme environments using machine learning

Determining the oxidation resistance of UHTC carbides in extreme environments is challenging theoretically and experimentally due to the high dimensional complexity of influencing variables and intricate testing setups. Herein we demonstrate the use of machine learning (ML) models trained with experimental literature data to predict the oxide thickness of UHTC carbides exposed to air based on composition, mean grain size, relative densification, holding time, and temperature. A multi-dimensional database with 76 occurrences is created containing experimental results of Hf, Zr, and Ta carbides plus additives. The preprocessed database is then used to train ML models to predict their oxidation behavior. The trained model predicts the oxidation damage in the form of an average oxide thickness in UHTC carbides with a Mean Absolute Error (MAE) of ±65.45 μm for samples in the testing set that developed thicknesses up to 1000 μm. The model successfully predicted oxidation damage for a recession rate lower than 60 μm/min. It is noticed that the ensemble method MAE is increased to ±134.34 μm while forecasting the oxidation of samples with a recession rate higher than the threshold. The unprecedented approach is a novel way to predict the damage through the oxidation of carbide compounds before processing for a smarter design with room for improvement.

Antifungal Synergistic Effect of Paprika and Cinnamon Oleoresins and Their Coencapsulation by Spray Chilling Technique to Produce a Carotenoid-Cinnamaldehyde-Rich Food Powder

Oleoresins are natural extracts obtained from plants and spices. Cinnamaldehyde and carotenoids are the main compounds found in cinnamon and paprika oleoresins, respectively, and exhibit pronounced antimicrobial and antioxidant potential. The coencapsulation of the two oleoresins can promote greater stability and synergism between them. Microencapsulation by spray chilling generates solid lipid microparticles when the atomized matrix crystallizes in contact with the cold chamber. This technique allows greater trapping of volatile compounds as they are more soluble in lipid materials. This work’s main objective was to evaluate the synergistic antifungal effect between cinnamon and paprika oleoresins and their coencapsulation by spray chilling. Cinnamon:paprika (1:1 and 2:1) mixture showed a synergistic effect against Penicillium paneum and Aspergillus niger. The extracts also prevented the growth of microorganisms without direct contact with the agar. The microparticles showed a spherical surface and polymorphic β′-characteristic. Particles containing paprika oleoresin presented orange color, while samples with only cinnamon were off-white. The size distribution was multimodal with (D0.5) ranging from 13.6 μm for samples containing only cinnamon to 1152.7 μm for samples containing only paprika oleoresin. The storage temperature (5 and 25 °C) affected the release of cinnamaldehyde from the microparticles. Regarding the first 14 days, samples stored at 5 °C released more cinnamaldehyde compared to that stored at 25 °C. The concentration of carotenoids in the particles remained constant throughout the 49 days of storage for both temperatures. The coencapsulation of oleoresin from paprika and cinnamon made it possible to obtain a lipid coloring powder that has antimicrobial properties.

Microplastic Contamination in Urban, Farmland and Desert Environments along a Highway in Southern Xinjiang, China.

The different types of microplastics (MPs), including debris, fibers, particles, foams, films and others, have become a global environmental problem. However, there is still a lack of research and understanding of the pollution characteristics and main causes of MPs in the arid region of Xinjiang, China. In this survey, we focused on the occurrence and distribution of MPs in urban, farmland and desert areas along a highway in the survey area. Our results showed that the main types of MPs were polypropylene (PP) flakes, polyethylene (PE) films and both PE and PP fragments and fibers. The abundance levels of MPs in street dust of Korla, Alar and Hotan districts equaled 804, 307 and 1526 particles kg−1, respectively, and were positively correlated with the urban population. In farmland areas, there were only two types of MPs (films and fibers), of which the film particles dominated and accounted for 91% of the total on the average. The highest abundance rate of MPs reached 7292 particles kg−1 in the desert area along the highway. The minimum microplastic particle sizes were 51.8 ± 2.2 μm in urban street dust samples, 54.2 ± 5.3 μm in farmland soil samples and 67.8 ± 8.4 μm in samples from along the desert highway. Particle sizes < 500 μm were most common and accounted for 48–91% of the total in our survey. The abundance and shape distribution of the MPs were closely related to the different types of human activities.

Multistep Super Resolution Double-U-net (SRDUN) for enhancing the resolution of Berea sandstone images

Digital Rock Physics (DRP) has opened a new avenue through the microscale world of rocks leading to more detailed inferences. However, High Resolution (HR) images are problematic from several aspects such as low field of view, huge memory and long time and high cost of image acquisition. Recent advances in Machine Learning (ML) and especially Convolutional Neural Networks (CNN) highly improved the ability of producing HR images from their Low Resolution (LR) counterparts known as Super Resolution (SR) images. In this procedure, the scale-difference between LR and HR images is a key parameter, while a high scale-difference leads to unreliable results regardless of the method. To overcome such a problem, we aim to both propose a multiscale procedure and introduce an efficient network namely Super Resolution Double-U-net (SRDUN). To this end, unlike conventional studies where LR images are synthetically produced from HR images, we capture these images from a Berea sandstone individually in five different scales (16.263, 12.922, 9.499, 5.775 and 3.501 μm for samples with a side of 10, 8, 6, 4 and 2-mm). Then, the SRDUN is introduced, where a first U-net is used to store feature maps of HR images and are imported in a second U-net as informative skip connections. Results show SRDUN could perform more accurate than common networks for small scale-differences. However, when it comes to high scale-differences it becomes more complicated. We propose a multistep procedure, where several mid-step SRDUNs are used to fill the gap of information. Results of this procedure reveal that the multistep procedure could perform much better than the direct approach. These results are then demonstrated by some computations of reservoir parameters such as porosity, pore equivalent diameter distribution, morphometric properties and permeability. Porosity and permeability computations showed that the error of computed values from SR images is increased by increasing scale-difference, however, the multistep procedure leads to more reliable results. The multistep procedure could preserve better the pore size distribution, however, in morphometric properties, the direct approach performs better since the multistep procedure suffers from a smoothing effect.

Formation of grain structure and its change during the superplastic deformation of samples of alloys Al-4,1 wt.% Cu-0,5 wt.% Zr, 1450 and 1460, doped with zirconium and scandium

The article presents the results of research aimed at establishing the mechanisms of formation of ultrafine-grained structure in samples of Supral Al-4.1 wt.% Cu-0.5 wt.% Zr, 1450 and 1460 alloys, containing dispersed particles of zirconium and scandium aluminides which are effective stabilizers of the microstructure as well as at establishing the peculiarities of its change during superplastic deformation. It is established that static recrystallization plays an important role in the formation of ultrafine-grained grain structure with an average grain size d =5 μm in samples of the alloy Al-4.1 wt.% Cu-0.5 wt.% Zr. It takes place during their heating in air to the test temperature T = 773 K. Finally, the formation of the grain structure in the samples is completed in the initial stages of their superplastic flow due to the passage of continuous dynamic recrystallization. It was found that the grain structure in the working parts of the samples of the alloy Al-4.1 wt.% Cu-0.5 wt.% Zr, superplastically deformed to fracture by hundreds of percent, is ultrafine-grained ( d ≈10 μm) and equiaxed. It is established that recrystallization annealing of 1450 alloy samples does not lead to the formation of a homogeneous fine-grained structure in them. It is shown that an almost homogeneous microstructure with an average grain size d =3÷6 μm is created directly during their superplastic deformation at temperatures of 753, 763, 773, 778K and flow stresses σ = 2,0 ¸ 8,0 MPа to degrees of relative deformation εrel, amounting to 20-50%, due to the implementation of continuous dynamic recrystallization. During the subsequent stages of the superplastic flow, the average grain size increases in the working part of the samples of alloy 1450. It is shown that in the samples of alloy 1450, which were deformed to failure under the optimal conditions, the grains retain an equiaxed shape, and their average size is 10 – 15 μm. It is established that the ultrafine-grained grain structure in the working parts of samples of alloy 1460 with an average grain size d =5 μm increases during their superplastic deformation, which is carried out at temperatures in the range T = 753÷853 K and at flow voltages σ equal to 3.0÷6.0 MPa. It is shown that in samples of alloy 1460, which were deformed to failure by 1000% at Т = 823 К and s = 3,5 MPa, average grain size d ≈15 μm.

Evaluation of the Mechanical Properties and Drilling of Glass Bead/Fiber-Reinforced Polyamide 66 (PA66)-Based Hybrid Polymer Composites.

In this study, mechanical testing of glass bead (GB), glass fiber (GF), and hybrid (GB/GF) composites was carried out. Following that, drilling tests were undertaken on glass bead/fiber-reinforced hybrid Polyamide 66 (PA66) polymer composites. The purpose of this study is to determine the mechanical properties of the cutting elements and the effect of cutting parameters (spindle speed and feed rate) and reinforcement ratios on thrust force and surface roughness (Ra). The contribution of the cutting parameters to the investigated outcomes was determined using statistical analysis. Optical microscopy and scanning electron microscopy (SEM) was used to inspect the hole quality and damage mechanisms. The results revealed that the feed rate was the most contributing factor to thrust force (96.94%) and surface roughness (63.59%). Furthermore, in comparison to other hybrid composites, the lowest Ra value was obtained as 0.95 µm in samples containing 30% GB, while the Ra value was 1.04 µm in samples containing 10% GF + 20% GB. Polymer PA reinforced with 30% GF had the highest strength, modulus of elasticity, impact strength, and hardness.

Microfluidic Device for the Identification of Biological Sex by Analysis of Latent Fingermark Deposits.

To date, most research regarding amino acid detection and quantification in fingermarks relies on spectrometric methods. Herein, the Sakaguchi colorimetric test was adapted to a rotationally-driven microfluidic platform and used to detect and quantify arginine in fingermarks deposited by male and female donors. A red color indicates the presence of arginine in a given sample following the reaction, and the intensity of this color is linearly proportional to the concentration. Objective detection and quantification of arginine were accomplished using image analysis software (freeware) based on this colorimetric result. The mean concentrations obtained in a blind study were 96.4 ± 5.1 µM for samples from female donors and 55.3 ± 5.3 µM for samples from males. These were not statistically different from the literature values of 94.8 µM ± 12.9 µM for females (p = 0.908) and 54.0 ± 12.6 µM for males (p = 0.914), respectively (± SEM in all cases). Conversely, the experimental means from males and female samples were statistically different from each other (p < 0.001). Objective differentiation between male and female fingermark deposits was achieved in a blind study with 93% accuracy. Additionally, the method was compatible both with samples lifted from common surfaces and with magnetically-powdered samples.

Effect of Multidirectional Forging and Subsequent Annealing to the Microstructure of Al-Mg-Mn Type Alloy

The grain refinement is important to improve both service properties at room temperature and superplasticity at elevated temperatures. This study focuses on the effect of multidirectional forging in isothermal conditions on the microstructure of Al-Mg-Mn-type alloy. The evolution of dislocation and grain structure, and precipitates of Mn-rich phase during multidirectional forging in a temperature range of 200 to 500 °C was studied. Multidirectional forging at temperatures of 200 and 300 °C leads to the formation of shear bands in the deformed grains. The multidirectional forging at 400 and 500 °C leads to the formation of a bimodal grain structure with fine- and coarse-grained areas. Subsequent recrystallization annealing at 500 °C increases the grain size and decreases the fine grains fraction in the samples pre-deformed at 400-500°C, and, on the contrary, annealing leads to formation homogeneous and fine grain structure with size up to 6.5 μm in samples pre-deformed at 200 and 300 °C.

Occurrence of tire and bitumen wear microplastics on urban streets and in sweepsand and washwater

Tire and road wear particles have been identified as a potential major source of microplastics in the environment. However, more knowledge of the emissions and their further fate in the environment is needed, and the effectiveness and benefits of potential measures must be investigated to support future risk management efforts. Here the concentrations of tire and bitumen microplastic particles (TBMP) on roads and in nearby in stormwater, sweepsand and washwater were measured for the first time within the same area and time period. The analysis also included plastic, paint and fiber particles. Road dust was sampled on the road surface using a wet dust sampler, before and after street sweeping on two occasions. On each of these occasions, and several occasions during a four-month period with frequent street sweeping, sweepsand and washwater, as well as flow-weighted sampling of stormwater, were collected. TBMP concentrations were operationally defined, using density separation for some samples, followed by analysis by stereo microscopy. Sodium iodide (NaI) was found to be effective for density separation of TBMP. The largest proportion of anthropogenic microplastics detected consisted of tire tread wear and bitumen. The number of TBMP ≥100 μm in the WDS samples was up to 2561 particles/L. Sweepsand and washwater contained high amounts of TBMP ≥100 μm, up to 2170 particles/kg dw and 4500 particles/L, respectively. The results show that the sweeper collects considerable amounts of TBMP, and thus weekly sweeping might prevent further transport of TBMP to the receiving stormwater. In stormwater the number of particles ≥100 μm was up to 3 particles/L and ≥ 20 μm was up to 5900 particles/L showing the importance of analysing smaller microparticle sizes than 100 μm in all samples in future studies. This study also confirms that there is a substantial volume of TBMP generated from traffic that enters the environment.

Enhancing the Mechanical Properties of Si Particle Reinforced ZA22 Composite by Ti–B Modification

In situ precipitation of primary Si (SiP) particles within the microstructure of Si-containing Zn–22Al alloys, also known as ZA22/SiP composites, can improve their hardness and mechanical strength, provided that the size, morphology, and distribution of SiP particles are optimized. In this study, Ti–B treatment was employed to modify the microstructure and improve the mechanical properties of ZA22–xSi (x = 4 and 8 wt%) composite. According to the results, Ti–B treatment eliminated the primary α-Al dendrites, reduced the volume fraction of remaining α-Al phase within the microstructure, reduced the size of SiP particles, and improved their distribution within the matrix. Moreover, the size of SiP particles is reduced from 25.2 ± 9.5 to 30.1 ± 4.4 μm in non-modified samples containing 4 and 8 wt% Si to 14.7 ± 6.3 and 19.6 ± 5.3 μm in the samples modified by Ti–B, respectively. Ti–B addition also substantially refined and homogenized the distribution of the other second phases and porosities. The mechanical properties analyses revealed that, at a given Si concentration, the hardness of the alloys modified by Ti–B was relatively less than that of the non-modified ones. Moreover, the tensile strength and fracture strain of modified ZA22–4Si and ZA22–8Si composites are increased by about 15 and 59, and 60 and 82%, respectively.

Farklı Biyokütlelerden Elde Edilen Nişasta İle Akıllı Biyoplastik Malzeme ve Odun Biyoplastik Kompozit Üretimi

The aim of this study is to produce eco-friendly alternative bioplastic and wood biocomposite packaging materials based on starch, derived from different biomasses, in order to minimize the damage caused by petroleum derivative packages to human health and the environment. For this purpose, solubility in water (%), water absorption (%), density according to ASTM D 792 (g/cm 3 ) and surface roughness values according to ISO 4287 standard were determined. According to the results obtained; the highest and lowest water solubility values are sample D with 100 % and sample F with 8.01 %, respectively. The highest and lowest water absorption (%) capacity with value of % 242 as sample B and as 108 % with the sample E were measured respectively. The most uniform surface was obtained by the values Ra, Rz and Rmax, as 3.53, 18.8 and 25.1 µm for sample A while the highest surface roughness with respectively as 10.4, 43.8 and 55.0 µm values for sample D was determined.

Microstructure evolution and mechanical properties of 316L austenitic stainless steel with aluminum addition by warm rolling

Microstructure evolution and mechanical properties of 316L austenitic stainless steel with aluminum addition by warm rolling at 550 °C were investigated. It is found that sample is composed of an ashen austenite matrix, a gray black ferrite phase and a small number of NiCx. The average grain sizes are 21.62, 19.66 and 19.49 μm for samples with the rolling deformation of 30%, 50% and 70%, respectively. The yield strength and tensile strength of samples with solid solution time of 30 min and deformation of 70% are higher. The fracture modes are similar and belong to toughness fracture. The fracture surfaces of the samples are composed of relatively large equal-axis ductile dimples (5–15 μm) and fine scattered ones around the dimples ( orientation is more prominent. {001} rotation-cube textures are present in ferrite phase of samples and weak Goss texture is formed in austenite pole images.

Superconductivity of Y2O3 and BaZrO3 nanoparticles co-added YBa2Cu3O7−δ bulks prepared using co-precipitation method

In this work, polycrystalline samples of nominal composition YBa2Cu3O7−δ with co-addition of 5.0 mol% of Y2O3 and x mol% of BaZrO3 (BZO) nanoparticles (x = 0.0, 1.0, 2.0, 3.0, 5.0 and 7.0) were prepared using co-precipitation (COP) method. Data of X-ray diffraction (XRD) showed that all the samples were composed of Y-123 as the major phase and Y-211 as the minor phase. XRD peak of BZO was also observed in the samples co-added with BZO nanoparticles. Refinement of lattice parameters of a, b, and c-axis showed that the orthorhombic structure of the samples was retained without occurance of orthorhombic-tetragonal phase transition. The average grain size was increased from 0.30 ± 0.02 µm for the pure sample to 0.47 ± 0.03 µm for the sample with 7.0 mol% BZO as revealed by the scanning electron microscope images. Plots of normalized resistance versus temperature showed metallic behavior in the normal state and a single step transition in the samples. Tc-onset was decreased with co-addition of Y2O3 and BZO probably because of reduced hole concentration. The higher Josephson’s current, Io of the samples with co-addition of 0.0–2.0 mol% BZO compared with that of the pure one is likely to be due to improved grain coupling as shown by the AC susceptibility measurement. The calculated intergranular critical current density, Jcm based on the Bean critical state model is 1.88 A/cm2 at Tp = 84.8 K for the pure sample. The highest Jcm obtained is 2.10 A/cm2 at Tp = 85.4 K for 2.0 mol% BZO co-added sample.

Hydride formation during cathodic charging and its effect on mechanical properties of a high Nb containing TiAl alloy

Due to their high specific strength and modulus at evaluated temperature, high Nb containing TiAl alloys have attracted extensive interest as prospective structural material for aerospace. However, low ductility as well as long-term expose to hydrogen still impedes its wide application in aerospace industries. This work focuses on hydrides' formation during cathodic charging and its effect on microstructure and mechanical properties of a high Nb containing TiAl alloy with the composition of Ti45Al8.5Nb-(W, B, Y). A hydride (TiAl)Hx with tetragonal crystal structure has been observed in alloys charged at 20, 100 and 500 mA/cm2 for 24 h. With the increase of current intensities, the thicknesses of hydride layer are around 2, 6 and 20 μm in samples charged at 20, 100 and 500 mA/cm2 for 24 h, respectively. The hydride layer exhibits loose and polyporous structure. The hydrogen diffusion coefficient of the alloy charged at 20 mA/cm2 for 24 h has been evaluated to be 6.33 × 10−16 m2/s by the nano-hardness from the distribution of the hydride layer. The tensile strengths of the alloys charged at 20, 100 and 500 mA/cm2 are 485, 476 and 405 MPa, while the strains are 0.699, 0.659 and 0.558, respectively.

Influence of solidification conditions and alloying elements Re and Ti on micropores formed during homogenization of Ni base single crystal superalloy

The influence of withdraw rate during directional solidification and elements Re and Ti on the formation of micropores during homogenization in Ni base single crystal superalloy CMSX-4 is investigated by X-ray tomography method. The results show that the number of micropores below 5 μm in sample solidified at 10 mm/min after homogenization at 1300 °C/3 h is greater than that in the case of 6 mm/min. The number of micropores below 10 μm in Re free and Ti free alloys is rather smaller than that of normal CMSX-4 alloy, while the number of micropores between 15 μm and 25 μm in Ti free alloy is relatively greater than that in Re free alloy. The variation of number of micropores is analyzed based on measurement of primary dendrite arm spacing (PDAS) and segregation ratios of alloying elements, the causes are mainly attributed to reverse segregation tendencies of Re and Ti and their remarkable diffusion coefficient difference, the increasing of PDAS also enhances the propensity of micropores formation during homogenization.

Length-Dependent Activation is Reduced in Myocardium from Patients with Non-ischemic Heart Failure

Heart failure contributes to 1 in 9 deaths in the United States and often reflects impaired cellular-level contractile function. In healthy hearts, the myofilaments become more sensitive to Ca2+ as the myocardium is stretched. This effect is known as length-dependent activation and is the cellular-level basis of the Frank-Starling mechanism. Few studies have measured the magnitude of length-dependent activation in myocardium from failing human hearts. Multicellular preparations from the left ventricular free wall were chemically permeabilized and Ca2+-activated at sarcomere lengths of 1.9 and 2.3 µm, at physiological temperature (37°C). 12 hearts were explanted from patients receiving cardiac transplants; 6 patients had ischemic heart failure and 6 had non-ischemic heart failure. Another 6 hearts were obtained from organ donors. Calcium-sensitivity of contraction (defined as the pCa50 value) increased by 0.07 pCa units as the preparations were stretched from 1.9 to 2.3 µm in samples from organ donors (p<0.001) and ischemic failing hearts (p=0.003). Calcium-sensitivity did not change with sarcomere length in preparations from non-ischemic failing hearts. These data show for the first time that length-dependent activation of contraction is preserved in myocardium from patients with ischemic heart failure, but eliminated in myocardium from patients with non-ischemic heart failure. Because length-dependent activation is an important component of the Frank-Starling mechanism, patients who have non-ischemic disease may exhibit a diminished contractile response to increased ventricular filling. Different therapeutic strategies may be more effective in patients with ischemic and non-ischemic heart failure.