Low-density Fraction Research Articles

New Insights into F-Cells, F-Reticulocytes and the Role of Fetal Hemoglobin in Protecting Sickle Red Cells from Hemolysis upon Mechanical Stress

Sickle cell disease (SCD) is an autosomal hereditary recessive disorder caused by a single point mutation in the first exon of the β-globin gene generating abnormal hemoglobin (HbS). Hypoxia drives HbS polymerization and fiber formation that are responsible for red blood cell (RBC) sickling. In SCD patients expression of fetal hemoglobin (HbF) is higher than in healthy individuals and varies considerably. Although clinical studies have shown that HbF levels were inversely correlated with disease severity, studies addressing the relationship between the expression level of HbF at the cellular level, i.e. in F-cells, and the impact on RBC morphology and survival are scarce.In this study, we investigated the distribution and the expression level of HbF at the cellular level in a large cohort of SCD patients (SS or Sβ°) using high throughput imaging techniques, functional sickling assays and a novel microfluidic device.We determined the percentage of HbF-expressing cells (F+RBCs) in 46 patient blood samples and found that it was highly variable (mean: 44% +/- 24%) and correlated with the percentage of HbF measured by HPLC (R2 = 0.86). To estimate the content of HbF in F+RBCs at the single cell level we developed a method based on imaging flow cytometry and defined three different populations according to the expression level of HbF: low, medium and high F+RBCs (Figure 1). We determined the percentage of each subpopulation in 30 SCD blood samples and found that the low F+RBCs were the most prevalent, with a median of 17.85% of total circulating RBCs. The high F+RBCs were the least abundant, with a median of 0.63%, while medium F+RBCs accounted for 4.03% of RBCs.Next, we investigated the relationship between F+RBCs and irreversibly sickled cells (ISCs) using imaging flow cytometry. The %ISCs was significantly higher in the low than in the medium subpopulation and no ISCs were found in the high F+RBC subpopulation. Applying Percoll density fractionation we found that F+RBCs were predominant in the low dense (LD) fraction and poorly present in the high dense (HD) fraction; this was associated with low and high %ISCs in the LD and HD fractions, respectively.To investigate the potential role of HbF in the survival of circulating sickle RBCs we determined the percentage of F-cells within the reticulocyte and mature RBC populations using flow cytometry. Analyzing 46 blood samples, we found that the percentage of F+ reticulocytes (%F+Retics) was significantly lower than the percentage of F+ mature RBCs (%F+RBCs) within the same blood sample of all patients, indicating selective advantage of the F+Retics during maturation. We hypothesized that HbF might exert a protective effect by preserving the deformability of RBCs, protecting them from mechanical destruction. To investigate our hypothesis, we designed a microfluidic biochip to evaluate the resistance of F+RBCs undergoing repetitive mechanical stress, flowing through 5 x 5 μm channels (Figure 2). We measured the %F+RBCs in cell suspensions before (input) and after (output) flowing in the chip. We observed a significant increase of %F+RBC population in the output suspensions, indicating that F+RBCs withstand mechanical stress better than non-F-cells. Moreover, we found that high but not low F+RBCs were protected against lysis, indicating that a minimal threshold is needed for HbF to exert its protective role. In line with this finding, we measured the HbF/HbS ratio in the plasma (free hemoglobin) and in RBCs of SCD patients and found that it was much lower in the plasma, providing direct evidence that intravascular hemolysis targets RBCs with no or low HbF.Finally, there was no correlation between the percentage of reticulocytes and the %HbF or the %F+RBCs. However, a negative correlation was found between the percentage of reticulocytes and the %F+Retics, indicating that this latter is a more relevant marker of hemolysis and medullar regeneration than %HbF or %F+RBCs.Our study gives new insights into the role of the mechanical dimension as a critical contributing factor to anemia in SCD. It reveals a cellular mechanism through which HbF exerts its protective role in vivo, showing evidence that high HbF levels protect RBCs from increased density and from hemolysis upon mechanical stress. Our findings pave the way to future clinical studies in which the relationship between HbF expression at the early reticulocyte stage and clinical manifestations could be finely addressed. [Display omitted] DisclosuresBrousse:Add Medica: Membership on an entity's Board of Directors or advisory committees.

Grain size effect on tensile deformation behaviors of pure aluminum

Grain refinement is a very effective method to improve the mechanical properties of materials and attracts widespread interests among researchers. However, the grain size effect on the mechanical properties is still unclear due to the undesirable microstructure in ultrafine grained (UFG) materials. In the present work, series of ideal materials with average grain sizes range from 0.7 μm to 30.0 μm containing high fraction of high angle grain boundaries (HAGBs), equiaxed grains and low density of dislocations were produced by friction stir processing (FSP). It was found that the Hall-Petch relationships could be classified into three stages as the grain size reduced from coarse grain to UFG regimes, which were decided by the strengthening mechanisms during tensile deformation. The strengthening effect of HAGBs (71 MPa⋅μm1/2) was almost three times of low angle grain boundaries (25 MPa⋅μm1/2), resulting in the positive deviation of Hall-Petch slope in fine grain regime by the increased specific surface area of HAGBs. The further positive deviation of the Hall-Petch slope in UFG regime was affected by the occurrence of an extra dislocation source limited strengthening mechanism, which was up to 29 MPa and reached to about 20% of the yield strength. The increased recovery rate of dislocations at HAGBs contributed to the decrease of mobile dislocation density, leading to the losing of work hardening in UFG regime during tensile deformation.

Synergistic strengthening by nano-sized α-Al(Mn,Fe)Si and Al3Zr dispersoids in a heat-resistant Al–Mn–Fe–Si–Zr alloy

Strengthening by dispersoids in Al alloys has been limited by either low number density or low volume fraction of dispersoids. In the present work, the influence of an addition of 0.28 wt% Zr on precipitation hardening behavior of AA3003 alloy subjected to different heat treatments has been investigated. A superior microstructure simultaneously consisting of nano-sized α-Al(Mn,Fe)Si and Al3Zr dispersoids at peak-aged state was achieved by two different heat treatment regimes, ramp heating with a speed of 50 °C/h and isothermal aging at 400 °C. As a result, a substantial increase in yield strength of 30 MPa (43%) was achieved in comparison to AA3003 alloy. Meanwhile, the AA3003-Zr alloy exhibits excellent heat-resistance with a stable yield strength from 12h (106 MPa) up to 250h (107 MPa) during isothermal aging at 400 °C. This remarkable thermal stability was ascribed to the continuously hardening from Al3Zr precipitation, which compensates the strength loss from α-dispersoid coarsening. Besides, TEM study shows that the precipitation kinetics of Al3Zr is significantly enhanced compared with the reference binary Al–Zr alloy, which is attributed to the Si content in the alloy. This work proposes an effective method to design a low-cost heat-resistant Al alloy in mass production.

Proteomic and phospholipidomic characterization of extracellular vesicles inducing tumor microenvironment in Epstein-Barr virus-associated lymphomas.

Epstein-Barr virus (EBV) causes malignant carcinomas including B cell lymphomas accompanied by the systemic inflammation. Previously, we observed that phosphatidylserine (PS)-exposing subset of extracellular vesicles (EVs) secreted from an EBV strain Akata-transformed lymphoma (Akata EVs) convert surrounding phagocytes into tumor-associated macrophages (TAMs) via induction of inflammatory response, which is in part mediated by EBV-derived micro RNAs. However, it is still unclear about EV-carried other potential inflammatory factors associated with TAM formation in EBV lymphomas. To this end, we sought to explore proteomic and phospholipidomic profiles of PS-exposing EVs derived from EBV-transformed lymphomas. Mass spectrometric analysis revealed that several immunomodulatory proteins including integrin αLβ2 and fibroblast growth factor 2 (FGF2) were highly expressed in PS-exposing Akata EVs compared with another EBV strain B95-8-transformed lymphoma-derived counterparts which significantly lack TAM-inducing ability. Pharmacological inhibition of either integrin αLβ2 or FGF2 hampered cytokine induction in monocytic cultured cells elicited by PS-exposing Akata EVs, suggesting the involvement of these proteins in EV-mediated TAM induction in EBV lymphomas. In addition, phospholipids containing precursors of immunomodulatory lipid mediators were also enriched in PS-exposing Akata EVs compared with B95-8 counterparts. Phospholipidomic analysis of fractionated Akata EVs by density gradient centrifugation further demonstrated that PS-exposing Akata EVs might be identical to certain Akata EVs in low density fractions containing exosomes. Therefore, we concluded that a variety of immunomodulatory cargo molecules in a certain EV subtype are presumably conducive to the development of EBV lymphomas.

INCREASED LIFE EXPECTANCY BASED ON PHYSICAL FORMULAS

Life expectancy is due to the frequency of processes occurring in the body. The lower the frequency, the longer the lifespan. The frequency is influenced by the fraction of vacuum particles in a free, unbound state. Elementary particles are connected, grouped particles of vacuum. But in a free state, a large proportion of them affect the frequency of oscillations, increasing it, therefore, reducing the lifetime. The connection between a living organism and an inanimate body has been drawn. Dislocations are analogous to vacuum particles. Their low density and low fraction of vacuum particles describe the theoretical ultimate strength and lifetime. The increase in density and the formation of crystalline elementary particles cause the average lifetime and average strength, orders of magnitude smaller than the theoretical one. A further increase in the dislocation density causes cracks and ruptures, and partly chaotic formation — tumors, partly crystalline. Chaos and order are described by a complex unified field that causes tumors. This unified field is described by the hydrodynamic, acoustic, complex Reynolds number with a small imaginary part. But the formation of a small imaginary Reynolds number is an inevitable process with increasing time, as is the formation of tumors. But how to deal with them. It is necessary for the tumors to pass from a partially chaotic state to a crystalline one, forming elementary particles. This requires a periodic unified field with a wavelength equal to a constant period, which is formed by vacuum particles in elementary, crystalline particles. In addition, an imaginary magnetic field is required, which has a sign opposite to the Reynolds number. Just irradiating the tumor will not help, you need a certain wavelength and a certain sign of the imaginary magnetic

IMMATURE LOW-DENSITY NEUTROPHILS AS MEDIATORS OF PYODERMA GANGRENOSUM AND INFLAMMATORY BOWEL DISEASE PATHOGENESIS

Pyoderma gangrenosum (PG) is a debilitating skin condition characterized by deep, pus-filled, non-healing ulcers packed with neutrophils and is a common extraintestinal manifestation of inflammatory bowel disease (IBD). Strikingly, ∼40% of people with an initial presentation of PG go on to be also diagnosed with IBD, suggesting that both diseases have common factors driving their pathogenesis. The molecular and cellular mechanisms of PG and IBD co-development are currently unknown, hampering the development of effective treatment strategies for individuals affected by both diseases. Prior studies of individuals with PG demonstrate an enrichment of circulating immature low-density neutrophils (LDGs) that are sensitized to undergo NETosis, a specialized form of cell death. NETosis induces inflammation and, when dysregulated, can promote chronic cycles of inflammation. We hypothesize that LDGs mediate NETosis-driven inflammation in both PG and IBD, but the LDGs from individuals that develop both diseases are functionally distinct. In this translational study, blood samples are collected from healthy subjects or individuals with only PG, only Crohn’s disease, only ulcerative colitis, or individuals with both PG and IBD for the analysis of neutrophil populations, neutrophil function, as well as circulating markers of inflammation and NETosis. Preliminary data from 45 subjects demonstrate an enrichment of circulatory LDGs (CD45+ CD15+ CD66b+ CD10+ CD16+ cells from the low density fraction) in individuals with inflammatory disease as compared to healthy subjects (19.2% +/- 2.81%, n=41 vs. 9.9% +/- 2.9%, n=4; p=0.04). This is correlated with increased NETosis in vitro, however differences in the responsiveness of LDGs to priming signals, such as IL-1β, TNFα, and IL-6, are emerging between disease sub-groups. There is considerable variation in the levels of LDGs within disease sub-groups and analyses are underway to determine whether this variation correlates with subject reported disease activity, inflammatory markers (serum C-reactive protein), or circulating markers of NETosis (serum citrullinated histone 3). These preliminary findings point to the presence of a unique population of cells potentially contributing to inflammatory cross-talk between the skin and gut. Further analysis of these potentially disease driving cells may result in more effective care of IBD patients with extraintestinal manifestations, such as PG, through more mechanistically targeted therapeutic approaches, as well as potential biomarker discovery that predicts which PG patients are more likely to develop IBD leading to earlier intervention and better disease outcomes.

IMMATURE LOW-DENSITY NEUTROPHILS AS MEDIATORS OF PYODERMA GANGRENOSUM AND INFLAMMATORY BOWEL DISEASE PATHOGENESIS

Abstract Pyoderma gangrenosum (PG) is a debilitating skin condition characterized by deep, pus-filled, non-healing ulcers packed with neutrophils and is a common extraintestinal manifestation of inflammatory bowel disease (IBD). Strikingly, ~40% of people with an initial presentation of PG go on to be also diagnosed with IBD, suggesting that both diseases have common factors driving their pathogenesis. The molecular and cellular mechanisms of PG and IBD co-development are currently unknown, hampering the development of effective treatment strategies for individuals affected by both diseases. Prior studies of individuals with PG demonstrate an enrichment of circulating immature low-density neutrophils (LDGs) that are sensitized to undergo NETosis, a specialized form of cell death. NETosis induces inflammation and, when dysregulated, can promote chronic cycles of inflammation. We hypothesize that LDGs mediate NETosis-driven inflammation in both PG and IBD, but the LDGs from individuals that develop both diseases are functionally distinct. In this translational study, blood samples are collected from healthy subjects or individuals with only PG, only Crohn’s disease, only ulcerative colitis, or individuals with both PG and IBD for the analysis of neutrophil populations, neutrophil function, as well as circulating markers of inflammation and NETosis. Preliminary data from 45 subjects demonstrate an enrichment of circulatory LDGs (CD45+ CD15+ CD66b+ CD10+ CD16+ cells from the low density fraction) in individuals with inflammatory disease as compared to healthy subjects (19.2% +/- 2.81%, n=41 vs. 9.9% +/- 2.9%, n=4; p=0.04). This is correlated with increased NETosis in vitro, however differences in the responsiveness of LDGs to priming signals, such as IL-1β, TNFα, and IL-6, are emerging between disease sub-groups. There is considerable variation in the levels of LDGs within disease sub-groups and analyses are underway to determine whether this variation correlates with subject reported disease activity, inflammatory markers (serum C-reactive protein), or circulating markers of NETosis (serum citrullinated histone 3). These preliminary findings point to the presence of a unique population of cells potentially contributing to inflammatory cross-talk between the skin and gut. Further analysis of these potentially disease driving cells may result in more effective care of IBD patients with extraintestinal manifestations, such as PG, through more mechanistically targeted therapeutic approaches, as well as potential biomarker discovery that predicts which PG patients are more likely to develop IBD leading to earlier intervention and better disease outcomes.

Exploring the Strain Hardening Mechanisms of Ultrafine Grained Nickel Processed by Spark Plasma Sintering

Ultrafine grained (UFG) materials in the bigger grain size range (0.5–1) µm display a good combination of strength and ductility, unlike smaller size UFG and nanostructured metals, which usually exhibit high strength but low ductility. Such difference can be attributed to a change in plasticity mechanisms that modifies their strain hardening capability. The purpose of this work is to investigate the work hardening mechanisms of UFG nickel considering samples with grain sizes ranging from 0.82 to 25 µm. Specimens processed combining ball milling and spark plasma sintering were subjected to monotonous tensile testing up to fracture. Then, microstructural observations of the deformed state of the samples were carried out by electron backscattered diffraction and transmission electron microscopy. A lower strain hardening capability is observed with decreasing grain size. Samples in the submicrometric range display the three characteristic stages of strain hardening with a short second stage and the third stage beginning soon after yielding. Microstructural observations display a low fraction of low angle grain boundaries and dislocation density for the sample with d = 0.82 µm, suggesting changes in plasticity mechanisms early in the UFG range.

Production of Hematopoietic Stem Cell-Chemotactic Factor by Bone Marrow Stromal Cells

Chemotactic factors produced by stromal cells in the bone marrow are characterized. Two kinds of factors produced by stromal cell lines are identified using blind-well Boyden's Chambers; one is a neutrophil-chemotactic factor and the other a hematopoietic stem cell (HSC)-chemotactic factor. The latter attracts blastic cells in a low-density fraction, which are Thy1lo, wheat germ agglutinin (WGA)hi, H-2Khi, Ly-1-, Ly-2-, L3T4-, Ly5-, and slg-. The molecular weight of this HSC-chemotactic factor is estimated to be more than 200 kD. Putative cytokines and growth factors, such as granulocyte colony-stimulating factor (CSF), macrophage CSF, granulocyte-macrophage CSF, stem cell factor (SCF), interleukin (IL)-6, and IL-3, do not possess HSC-chemotactic activity. These findings strongly suggest that bone marrow stromal cells produce a new factor that attracts HSCs.

Abstract 15589: Mitochondrial Metabolites Predict Cardiovascular Outcomes and Heart Failure in People With Type 2 Diabetes Mellitus and Vascular Disease: A Tecos Substudy

Introduction: People with type 2 diabetes mellitus (DM) have a large burden of cardiovascular (CV) morbidity and mortality, but the likelihood of these outcomes varies and existing risk calculators do not fully capture risk for individuals. Hypothesis: Circulating metabolites characterizing mitochondrial dysfunction may be novel predictors for CV outcomes. Methods: We performed targeted mass-spectrometry metabolite profiling (45 acylcarnitines, 15 amino acids) on baseline plasma samples from 568 cases (498 with major adverse cardiac events (MACE) and 131 with incident hospitalization for heart failure (hHF)) and 568 matched controls (without events) from the patients assigned to placebo in Trial Evaluating Cardiovascular Outcomes with Sitagliptin (TECOS). Matching was based on history of HF, coronary artery disease, BMI, hemoglobin A1C, creatinine, low-density lipoprotein cholesterol, fasting status and ejection fraction. Principal components analysis (PCA) was used for dimensionality reduction, and conditional logistic regression to determine association of PCA factors with MACE or hHF and for individual metabolites within significant factors (false discovery rate q<0.05) Results: Of 12 PCA-derived metabolite factors, three were associated significantly with MACE or hHF; these factors were composed of: 1) short-chain dicarboxylacylcarnitines and long chain acylcarnitines (OR 1.50, q=0.03); 2) medium chain acylcarnitines (OR 1.28, q=0.001); 3) C5:1 and one medium-chain dicarboxylacylcarnitine (OR 1.17, q=0.03). Of these three factors, none were significantly associated with the individual components of MACE. Ten individual metabolites, including short- and medium-chain dicarboxylacylcarnitines and medium- and long-chain acylcarnitines, remained significantly associated with MACE (q<0.05). Two metabolites, one short-chain dicarboxylacylcarnitine and one medium-chain acylcarnitine were associated with hHF (q<0.05). Conclusions: Metabolites reporting on dysregulated mitochondrial fatty acid oxidation and endoplasmic reticulum stress are elevated in individuals with DM who progress to MACE and/or hHF. These biomarkers may improve CV risk prediction in DM patients and help highlight emerging risk mechanisms.

Abstract 14727: Meteorin-like Glial Cell Differentiation Regulator is a Novel Protein Biomarker of Cardiovascular Outcomes in Patients With Diabetes and Vascular Disease: A TECOS Substudy

Introduction: To date, there are limited data on the potential role of proteomic biomarkers to predict future cardiovascular (CV) events among patients with type 2 diabetes mellitus (DM). Hypothesis: Specific protein biomarkers will be predictive of major adverse CV events (MACE) and incident heart failure hospitalization (HFH) among patients with DM. Methods: Using the Olink aptamer-based platform, we performed proteomic profiling (>700 proteins) on 440 paired cases and matched controls from placebo-assigned participants in the Trial Evaluating Cardiovascular Outcomes with Sitagliptin (TECOS). Cases were defined as having met the primary composite outcome of MACE or incident HFH and matched to controls on baseline prevalent heart failure, coronary artery disease, BMI, hemoglobin A1C, creatinine, low-density lipoprotein cholesterol, fasting status and ejection fraction. Conditional logistic regression was used to determine the association between log-transformed relative protein expression and incident MACE or HFH. False-discovery-rate (FDR) was used to adjust for multiple comparisons. Results: We identified three specific proteins that were significantly associated with prevalent MACE or HFH: METRNL, Notch 3, and ROR1 (OR 2.1, 1.6, 1.7 and q-value 0.01, 0.02, and 0.05 respectively) (Figure 1). METRNL, in particular, performed similarly to the established biomarker NT-proBNP (Figure 1). When MACE and HFH were analyzed separately, METRNL, in particular, remained strongly associated with both outcomes (OR 2.0, p<0.001 and OR 2.7, p=0.05). Conclusions: Three novel protein biomarkers, in particular METRNL (a circulating adipokine that regulates insulin-sensitivity), may identify diabetic patients at high risk for subsequent HF and MACE. Additional studies are needed to replicate these findings and uncover the biologic mechanism linking adipokine signaling and heart failure.

Effect of Different Amounts of Hybrid Barley in Diets on the Growth Performance and Selected Biochemical Parameters of Blood Serum Characterizing Health Status in Fattening Pigs

Simple SummaryThe aim of the present study was to determine the effect of dietary hybrid barley and/or wheat on production parameters, selected biochemical parameters of blood serum characterizing health status in fattening pigs. The use of hybrid barley as the basic ingredient of diets for fattening pigs provided similar production parameters as those obtained with wheat. No significant differences were noted in case of performance results and meatiness of fatteners. However, usage of hybrid barley with high level in diet decreased level of total cholesterol and LDL (low-density lipoprotein fraction) fraction in blood. It means that barley had a beneficial effect on blood lipid indices.The aim of the study was to determine the effect of dietary hybrid barley and/or wheat on production parameters, selected biochemical parameters of blood serum characterizing health status in fattening pigs. In group I, hybrid barley constituted 80% of feed; in II—wheat and hybrid barley were used, each in amount of 40% feed; in III—contained 80% of wheat. No significant differences were noted in case of performance results (body weight gains, feed intake, and feed conversion ratio) and meatiness of fatteners. All estimated biochemical indices determined in serum were within normal range. Usage of 80% hybrid barley decreased concentration of total cholesterol, low-density lipoprotein fraction (LDL), and triglycerides in blood (p < 0.05). However, high-density lipoprotein fraction (HDL) content increased (p < 0.01) up to 1.04 mmol·dm−3, comparing to the group with 80% of wheat (0.84 mmol·dm−3). Summarized, the diet with high level of barley had a beneficial effect on blood lipid indices, what indicate a good health status of all animals.

Human splenic polymorphonuclear myeloid-derived suppressor cells (PMN-MDSC) are strategically located immune regulatory cells in cancer.

In contrast to the mouse, functional assets of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSC) in the human spleen remain to be better elucidated. Here, we report that the spleen in gastric and pancreatic cancer adopts an immune regulatory character, harbors excessive amount of PMN-MDSC, and anatomically enables their interaction with T cells. Compared to the peripheral blood, the spleen from cancer patients contained significantly higher levels of low-density PMN-MDSC, but not early-stage MDSC (e-MDSC) and monocytic-MDSC (M-MDSC). Low-density fraction of polymorphonuclear (PMN) cells was enriched in immature myeloid cells and displayed higher levels of CD10, CD16, and ROS than their blood-derived counterparts. They were also positive for PD-L1, LOX-1, and pSTAT3. The white pulp and periarteriolar lymphoid sheath (PALS) were strategically surrounded by PMN cells that were in contact with T cells. Unlike those from the blood, both low-density and normal-density PMN cells from the human spleen suppressed T cell proliferation and IFN-γ production. Independent of clinical grade, high PMN-MDSC percentages were associated with decreased survival in gastric cancer. In summary, our results outline the immune regulatory role of the spleen in cancer where neutrophils acquire MDSC functions and feasibly interact with T cells.

Interaction of Autotaxin With Lipoprotein(a) in Patients With Calcific Aortic Valve Stenosis

Our objectives were to determine whether autotaxin (ATX) is transported by lipoprotein(a) [Lp(a)] in human plasma and if could be used as a biomarker of calcific aortic valve stenosis (CAVS). We first found that ATX activity was higher in Lp(a) compared to low-density lipoprotein fractions in isolated fractions of 10 healthy participants. We developed a specific assay to measure ATX-Lp(a) in 88 patients with CAVS and 144 controls without CAVS. In a multivariable model corrected for CAVS risk factors, ATX-Lp(a) was associated with CAVS (p=0.003). We concluded that ATX is preferentially transported by Lp(a) and might represent a novel biomarker for CAVS.

Analytical Determination of the Nucleation-Prone, Low-Density Fraction of Subcooled Water.

Subcooled water is the primordial matrix for ice embryo formation by homogeneous and heterogeneous nucleation. The knowledge of the specific Gibbs free energy and other thermodynamic quantities of subcooled water is one of the basic prerequisites of the theoretical analysis of ice crystallization in terms of classical nucleation theory. The most advanced equation of state of subcooled water is the IAPWS G12-15 formulation. The determination of the thermodynamic quantities of subcooled water on the basis of this equation of state requires the iterative determination of the fraction of low-density water in the two-state mixture of low-density and high-density subcooled water from a transcendental equation. For applications such as microscopic nucleation simulation models requiring highly frequent calls of the IAPWS G12-15 calculus, a new two-step predictor-corrector method for the approximative determination of the low-density water fraction has been developed. The new solution method allows a sufficiently accurate determination of the specific Gibbs energy and of all other thermodynamic quantities of subcooled water at given pressure and temperature, such as specific volume and mass density, specific entropy, isothermal compressibility, thermal expansion coefficient, specific isobaric and isochoric heat capacities, and speed of sound. The misfit of this new approximate analytical solution against the exact numerical solution was demonstrated to be smaller than or equal to the misprediction of the original IAPWS G12-15 formulation with respect to experimental values.

Soil particle density as affected by soil texture and soil organic matter: 2. Predicting the effect of the mineral composition of particle-size fractions

The particle density of soil (ρS) represents one of the basic physical properties of soil. However, measurement of this parameter is not part of common routine soil inventories in most countries. Therefore, pedotransfer functions (PTFs) were developed to calculate ρS. Here, we used a complex, hierarchically structured PTF to calculate ρS, separating the soil mineral substance (SMS) into clay, silt and sand fractions as well as separating the soil organic matter (SOM) into heavy-density and low-density fractions. This PTF was recently published, and here, we introduced an additional hierarchical level to consider the particle size fraction-dependent effect of the mineral composition on ρS. This extended PTF was calibrated and validated using data from soils of 16 German long-term experiments contrasting in soil texture and in soil mineral composition. Χ-ray diffraction analysis was applied to identify the mineralogical composition of the clay, silt and sand fractions. We fitted the particle densities of the identified minerals occurring in the respective particle size fractions by minimising the squared differences between the measured and predicted ρS. The model performed very well (RMSE = 0.011 Mg m−3 soil). According to the mechanistic base of the model and its hierarchical structure, it is very easy to include available information about the composition of any fraction or subfraction of soil mineral substances and to use the model to calculate the ρS corresponding to the specific site conditions.

Pathological validation and prognostic potential of quantitative MRI in the characterization of pancreas cancer: preliminary experience.

Patient stratification based on biological variation in pancreatic ductal adenocarcinoma (PDAC) subtypes could help to improve clinical outcome. However, noninvasive assessment of the entire tumor microenvironment remains challenging. In this study, we investigate the biological basis of dynamic contrast‐enhanced (DCE), intravoxel incoherent motion (IVIM), and R2*‐derived magnetic resonance imaging (MRI) parameters for the noninvasive characterization of the PDAC tumor microenvironment and evaluate their prognostic potential in PDAC patients. Patients diagnosed with treatment‐naïve resectable PDAC underwent MRI. After resection, a whole‐mount tumor slice was analyzed for collagen fraction, vessel density, and hypoxia and matched to the MRI parameter maps. MRI parameters were correlated to immunohistochemistry‐derived tissue characteristics and evaluated for prognostic potential. Thirty patients were included of whom 21 underwent resection with whole‐mount histology available in 15 patients. DCE K trans and v e, ADC, and IVIM D correlated with collagen fraction. DCE k ep and IVIM f correlated with vessel density and R2* with tissue hypoxia. Based on MRI, two main PDAC phenotypes could be distinguished; a stroma‐high phenotype demonstrating high vessel density and high collagen fraction and a stroma‐low phenotype demonstrating low vessel density and low collagen fraction. Patients with the stroma‐high phenotype (high k ep and high IVIM D, n = 8) showed longer overall survival (not reached vs. 14 months, P = 0.001, HR = 9.1, P = 0.004) and disease‐free survival (not reached vs. 2 months, P < 0.001, HR 9.3, P = 0.003) compared to the other patients (n = 22). Median follow‐up was 41 (95% CI: 36–46) months. MRI was able to accurately characterize tumor collagen fraction, vessel density, and hypoxia in PDAC. Based on imaging parameters, a subgroup of patients with significantly better prognosis could be identified. These first results indicate that stratification‐based MRI‐derived biomarkers could help to tailor treatment and improve clinical outcome and warrant further research.

Prion protein post-translational modifications modulate heparan sulfate binding and limit aggregate size in prion disease

Many aggregation-prone proteins linked to neurodegenerative disease are post-translationally modified during their biogenesis. In vivo pathogenesis studies have suggested that the presence of post-translational modifications can shift the aggregate assembly pathway and profoundly alter the disease phenotype. In prion disease, the N-linked glycans and GPI-anchor on the prion protein (PrP) impair fibril assembly. However, the relevance of the two glycans to aggregate structure and disease progression remains unclear. Here we show that prion-infected knockin mice expressing an additional PrP glycan (tri-glycosylated PrP) develop new plaque-like deposits on neuronal cell membranes, along the subarachnoid space, and periventricularly, suggestive of high prion mobility and transit through the interstitial fluid. These plaque-like deposits were largely non-congophilic and composed of full length, uncleaved PrP, indicating retention of the glycophosphatidylinositol (GPI) anchor. Prion aggregates sedimented in low density fractions following ultracentrifugation, consistent with oligomers, and bound low levels of heparan sulfate (HS) similar to other predominantly GPI-anchored prions. Collectively, these results suggest that highly glycosylated PrP primarily converts as a GPI-anchored glycoform, with low involvement of HS co-factors, limiting PrP assembly mainly to oligomers. Since PrPC is highly glycosylated, these findings may explain the high frequency of diffuse, synaptic, and plaque-like deposits in the brain as well as the rapid conversion commonly observed in human and animal prion disease.

Kinetics of bubble-particle attachment and detachment at a single-bubble scale

Bubble-particle attachment and detachment are fundamental subprocesses of flotation, a deep understanding of which is essential for predicting flotation kinetics. This paper focuses on the kinetics of bubble-particle attachment and detachment at a single-bubble scale. Kinetics experiments of attachment, detachment, and flotation using coal samples with low-density fraction (LDF), middle-density fraction (MDF), and high-density fraction (HDF) were conducted. Models of bubble-particle attachment and detachment kinetics were proposed by an analogy with flotation kinetics equations. With an increase in coal density, the attachment rate constant decreased, while the detachment rate constant increased, which was consistent with the decrease in floatability of coal. In addition, the experimental data of the attachment and detachment kinetics was compared with flotation kinetics (multi-bubble scale). The optimal fitted models for LDF and MDF were the classical first-order models of attachment/detachment/flotation kinetics. These consistencies indicated the floatability of coal could be characterized by the attachment and detachment kinetics at a single-bubble scale. This was not the case for HDF (gangue minerals in essence), since its optimal models of the attachment/detachment kinetics were the third-order models, while for flotation kinetics was the first-order model with rectangular distribution. This contradiction indicated the flotation of the high-density particles might be significantly affected by the bubble concentration.

Molecular dynamics simulation of the effects of swift heavy ion irradiation on multilayer graphene and diamond-like carbon

As a promising material used in accelerators and in space in the future, it is important to study the property and structural changes of graphene and diamond-like carbon on the surface as a protective layer before and after swift heavy ion irradiation, although this layer could have a loose structure due to the intrinsic sp2 surrounding environment of graphene during its deposition period. In this study, by utilizing inelastic thermal spike model and molecular dynamics, we simulated swift heavy ion irradiation and examined the track radius in the vertical direction, as well as temperature, density, and sp3 fraction distribution along the radius from the irradiation center at different time after irradiation. The temperature in the irradiation center can reach over 11000 K at the beginning of irradiation while there would be a low density and sp3 fraction area left in the central region after 100 ps. Ring analysis also demonstrated a more chaotic cylindrical region in the center after irradiation. After comprehensive consideration, diamond-like carbon deposited by 70 eV carbon bombardment provided the best protection.