Fractional Change Research Articles

Insight into spatial variations of DOM fractions and its interactions with microbial communities of shallow groundwater in a mesoscale lowland river watershed

Dissolved organic matter (DOM) plays a crucial role in driving biogeochemical processes and determining water quality in shallow groundwater systems, where DOM could be susceptible to dynamic influences of surface water influx. This study employed fluorescence excitation-emission matrix (EEM) spectroscopy combined with principal component coefficients, parallel factor analysis (PARAFAC), co-occurrence network analysis and structural equation modeling (SEM) to examine changes of DOM fractions from surface water to shallow groundwater in a mesoscale lowland river basin. Combining stable isotope and hydrochemical parameters, except for surface water (SW), two groups of groundwater samples were defined, namely, deeply influenced by surface water (IGW) and groundwater nearly non-influenced by surface water (UGW), which were 50.34 % and 19.39 % recharged by surface water, respectively. According to principal component coefficients, reassembled EEM data of these categories highlighted variations of the tyrosine-like peak in DOM. EEMs coupled with PARAFAC extracted five components (C1-C5), i.e. C1, protein-like substances, C2 and C4, humic-like substances, and C3 and C5, microbial-related substances. The abundance of the protein-like was SW > IGW > UGW, while the order of the humic-like was opposite. The bacterial communities exhibited an obvious cluster across three regions, which hinted their sensitivity to variations in environmental conditions. Based on co-occurrence, SW represented the highest connectivity between bacterial OTUs and DOM fractions, followed by IGW and UGW. SEM revealed that microbial activities increased bioavailability of the humic-like in the SW and IGW, whereas microbial compositions promoted the evolution of humic-like substances in the UGW. Generally, these results could be conducive to discern dissimilarity in DOM fractions across surface water and shallow groundwater, and further trace their interactions in the river watershed.

Short-term effects of irrigation and nitrogen management on paddy soil carbon pools under deep placement of basal fertilizer nitrogen

Active soil organic carbon (SOC) fractions are major driving factors of soil fertility. Understanding the effects of water and fertilizer management on changes in active SOC fractions helps improve soil quality and maintain high agricultural productivity. We conducted a 3-year field experiment in Northeast China. In this experiment, natural soil (CKT) was used as a blank, and two irrigation regimes were established: conventional flooded irrigation (FI) and controlled irrigation (CI). Four nitrogen application levels were set for both irrigation regimes under deep placement of basal fertilizer N: Nd0 (0 kg ha–1), Nd (110 kg ha–1), Nd1 (99 kg ha–1), and Nd2 (88 kg ha–1). After 3 years, at similar N fertilizer application rate, the rice yield, total organic carbon (TOC), and active SOC fraction content of CI were higher under CI than FI. The growth rate of rice yield was 3.8% − 8.63% under CI than FI. Under CI, the rice yield, active SOC fractions contents and carbon pool management index (CPMI) did not decrease with decreasing N application rate but instead reached the highest level in the CNd1 treatment. Overall, CI with Nd1 treatment appears to be the best practice for improving soil fertility and crop productivity in Northeast China.

CFD analysis of paraffin-based hybrid (Co–Au) and trihybrid (Co–Au–ZrO2) nanofluid flow through a porous medium

Abstract Ternary hybrid nanofluids possess improved thermal characteristics, enhanced stability, better physical strength, and multi-functionality as compared to hybrid or usual nanofluids. The aim of the ongoing study is to explore the novel thermal attributes of hybrid and trihybrid nanofluids through a porous medium. Whereas the nano-composition of cobalt (Co), gold (Au), and zirconium oxide (ZrO2) make amalgamation in the paraffin (Pfin) which is a base fluid. This nano-composition of the proposed nanoparticles, specifically, subject to the base fluid Pfin has not been interpreted before. The analysis not only covers the features of trihybrid nanofluids (Co–Au–ZrO2–Pfin) but it also describes the characteristics of hybrid (Co–Au–Pfin) as well as pure nanofluids (Co–Pfin). An efficient numerical algorithm is developed for which the numerical simulations are carried out. The approximations are performed in MATLAB software using “Successive under Relaxation (SUR)” technique. A comparison, under certain limiting conditions, with the established results appraises the efficiency of the numerical code. The outcomes evidently designate that temperature raises with the change in thermal radiation and volume fraction of gold and zirconium oxide in either case of pure, hybrid, or ternary nanofluids. The concentration ϕ 3 {\phi }_{3} of ZrO2 has a significant impact on Nusselt number rather than the concentration ϕ 1 {\phi }_{1} of cobalt and ϕ 2 {\phi }_{2} of gold. It has been comparatively noticed that the ternary nanofluids (Co–Au–ZrO2–Pfin) portray embellished and improvised thermal characteristics as compared to the other two cases.

CHANGES IN LEFT ATRIAL VOLUME DURING ECHOSTRESS IN PATIENTS UNDERGOING MITRAL VALVE PLASTIC CARDIAC SURGERY

Abstract Mitral Regurgitation (MR) is characterized by a high morbidity and mortality that often finds a solution only in the reparative surgical treatment, in particular in presence of myxomatous degeneration that cause the prolapse of one or both leaflets. This results in an increase in diastolic pressure that leads to a progressive dilation of the left atrium. The increase in Left Atrium Volume Index (LAVI) during stress test represents a negative prognostic factor in the clinical evolution of many pathologies, such as ischemic heart disease, hypertrophic cardiomyopathy, heart failure. An increase in peak/rest LAVI >6.8 ml/m2 correlates with a higher incidence of heart failure decompensation, reduced left ventricular contractile reserve (LVCR), pulmonary congestion. We evaluate the effect of MR reparative surgery on the changes of LAVI during stress–echo. We enrolled 19 patients, 11 females and 8 males, affected by MR candidate to cardiac surgery. We performed a physical stress–echo test by using the ABCDE protocol suggested by the Italian Society of Echocardiography and Cardiovascular Imaging (SIECVI), before and after 12 weeks from surgery. During each test, the changes in LAVI (ΔLAVI) expressed as peak/rest difference in ml/m2 was measured. In addition, the prognostic score deriving from the sum of the ABCDE criteria was calculated, such as the LVCR (C parameter of the score) that represents a parameter of the force deriving from the hemodynamic changes during the test. In all patients we observed a significant reduction in ΔLAVI (8.4+0.5 mL/m2 vs 9.7+0.7 mL/m2; p<0.0001). In addition, there was a significant reduction in the ABCDE prognostic score (from 4.19+0.43 to 3.48+0.37; p=0.002), secondary to the increase in the LVCR observed approximately 3 months after surgery (from 1.77 mmHg/ml to 2.44 mmHg/ml, p<0.0001), as well as a significant reduction in pulmonary congestion during stress (B parameter). There were no significant changes in ejection fraction, wall motion score index–WMSI (A parameter), coronary reserve (D parameter) and heart rate reserve (E parameter). These data demonstrate for the first time that mitral valve plastic surgery is able to reduce the ΔLAVI during stress echocardiography in patients with severe MR. The surgical procedure also resulted in both an improvement in the LVCR and a reduction in the degree of pulmonary congestion, that ultimately led to an improvement in the ABCDE prognostic score.

Symptom-to-balloon time and risk of ventricular arrhythmias in patients with STEMI undergoing percutaneous coronary intervention: The VERY-STEMI study

BackgroundVentricular arrhythmias (VAs) mainly occur in the early post-myocardial infarction (MI) period. However, studies examining the association between total myocardial ischemia time interval and the risk of new-onset VAs during a long-term follow-up are scarce. MethodsThis study (symptom-to-balloon time and VEntricular aRrhYthmias in patients with STEMI, VERY-STEMI study) was a multicenter, observational cohort and real-world study, which included patients with ST-segment elevation MI (STEMI) undergoing percutaneous coronary intervention (PCI). The primary endpoint was cumulative new-onset VAs during follow-up. The secondary endpoints were the major adverse cardiovascular events (MACE) and changes in left ventricular ejection fraction (ΔLVEF, %). ResultsA total of 517 patients with STEMI were included and 236 primary endpoint events occurred. After multivariable adjustments, compared to patients with S2BT of 24 h-7d, those with S2BT ≤ 24 h and S2BT > 7d had a lower risk of primary endpoint. RCS showed an inverted U-shaped relationship between S2BT and the primary endpoint, with an S2BT of 68.4 h at the inflection point. Patients with S2BT ≤ 24 h were associated with a lower risk of MACE and a 4.44 increase in LVEF, while there was no significant difference in MACE and LVEF change between the S2BT > 7d group and S2BT of 24 h-7d group. ConclusionsS2BT of 24 h-7d in STEMI patients was associated with a higher risk of VAs during follow-up. There was an inverted U-shaped relationship between S2BT and VAs, with the highest risk at an S2BT of 68.4 h.

Piezoresistive and capacitive cement-based stress sensors designed by incorporating carbon nanotubes doped with graphene nanopowder for structural health monitoring

Piezoresistive and capacitive cement-based smart composites are promising candidates for stress monitoring applications in buildings. However, the drawbacks of designing cement-based smart composites with a piezoresistive mechanism sensitive to temperature variations or a capacitive mechanism sensitive to vibration can be solved with sensor designs based on two principles. To address this issue, cement-based smart composites with piezoresistive and capacitive stress sensitivity and significantly improved compressive strength were designed using carbon nanotubes (CNT) doped with graphene nanopowder. A maximum fractional change in electrical resistivity of 90.08% with a high linearity of 98% was obtained with a blend of 0.01 wt%, and the maximum fractional change in capacitance was 163.11% with a high linearity of 97% at 0.05 wt%. Cement-based smart composites have absolute piezoresistive stress sensitivities that vary from 1.38% MPa−1 to 4.16% MPa−1 and 2.54% MPa−1 to 2.57% MPa−1 for blended and impregnated low doses of 0.01 wt% to 0.05 wt% CNT doped with graphene. In addition, capacitive stress sensitivities of 22.74% MPa−1 and 5.1% MPa−1 were achieved by blending and impregnating 0.01 wt% CNT doped with graphene in cementitious composites. Furthermore, the conductive path, overlapping, and tunneling effect created by CNT doped with graphene in cementitious composites and the porous structure in the dielectric layer are responsible for the increased stress sensitivity.

Metabolic effects of switching to Biktarvy (B/F/TAF) in patients with HIV-1 treated with antiretroviral regimens that do not include tenofovir disoproxil fumarate (TDF) or tenofovir alafenamide (TAF): The Metabic study.

Studies on switching to tenofovir alafenamide (TAF)-based regimens raise concerns about a worse metabolic profile in people with HIV, even though most received tenofovir disoproxil fumarate (TDF) in their previous regimen. This study aims to evaluate changes in lipid fractions, glucose, and serum markers for hepatic steatosis (HS) after switching from a TDF- or TAF-sparing regimen to bictegravir/emtricitabine/TAF (B/F/TAF). We performed a retrospective cohort study of people with HIV who switched to B/F/TAF from TDF- or TAF-sparing regimens between January 2019 and May 2022 with at least 6 months of follow-up. The primary endpoint was the absolute change in lipid fractions at 6 months. Secondary outcomes were changes in lipid fractions at 12 months and changes in other metabolic parameters (glucose, creatinine, and HS based on the triglyceride-to-glucose [TyG] ratio at 6 and 12 months). Changes were analysed using mixed linear regression models with random intercept and time as a fixed effect. The study included 259 people with HIV (median age 55 [interquartile range (IQR) 47-60] years; 80% male; 88% Caucasian; CD4+ T-cell count 675 [IQR 450-880] cells/mm3; 84.3% HIV-RNA <50 copies/mL). In total, 63 patients (30%) had hypertension, 93 (44%) dyslipidaemia, 30 (14%) diabetes, and 45% obesity/overweight. Most (60%) switched from integrase inhibitor-based regimens, and 21% switched from a boosted regimen. At 6 months, significant reductions were observed in total cholesterol (-7.64 mg/dL [95% confidence interval (CI) -13.52 to -1.76; p = 0.002]), triglycerides (-23.4 [95% CI -42.07 to -4.65]; p = 0.003), and TyG ratio (-0.14 [95% CI -0.23 to -0.05]; p < 0.001). In our real-life cohort, the effect of switching TDF-/TAF-sparing regimens to triple therapy with B/F/TAF improved total cholesterol, triglycerides, and serum markers of HS at 6 months and was neutral for the remaining metabolic parameters at 12 months.

Truncus arteriosus from prenatal diagnosis to clinical outcome: a single-centre experience.

The aim of this study was to review our institution's experience with truncus arteriosus from prenatal diagnosis to clinical outcome. and results: We conducted a single-centre retrospective cohort study for the years 2005-2020. Truncus arteriosus antenatal echocardiographic diagnostic accuracy within our institution was 92.3%. After antenatal diagnosis, five parents (31%) decided to terminate the pregnancy. After inclusion from referring hospitals, 16 patients were offered surgery and were available for follow-up. Right ventricle-to-pulmonary artery continuity was preferably established without the use of a valve (direct connection), which was possible in 14 patients (88%). There was no early or late mortality. Reinterventions were performed in half of the patients at latest follow-up (median follow-up of 5.4 years). At a median age of 5.5 years, 13 out of 14 patients were still without right ventricle-to-pulmonary artery valve, which was well tolerated without signs of right heart failure. The right ventricle demonstrated preserved systolic function as expressed by tricuspid annular plane systolic excursion z-score (-1.4 ± 1.7) and fractional area change (44 ± 12%). The dimensions and function of the left ventricle were normal at latest follow-up (ejection fraction 64.4 ± 6.2%, fractional shortening 34.3 ± 4.3%). This study demonstrates good prenatal diagnostic accuracy of truncus arteriosus. There was no mortality and favourable clinical outcomes at mid-term follow-up, with little interventions on the right ventricle-to-pulmonary artery connection and no right ventricle deterioration. This supports the notion that current perspectives of patients with truncus arteriosus are good, in contrast to the poor historic outcome series. This insight can be used in counselling and surgical decision-making.

Improvement in Left Ventricular Function of the Resected Myocardium after Septal Myectomy in Patients with Aortic Valve Replacement

Background: Some surgeons have previously advocated for a more aggressive concomitant septal myectomy to address left ventricular outflow tract obstruction; however, concerns about the surgical complications of post-septal myectomy remain. Here, we aimed to assess the clinical, echocardiographic, and pathological findings following concomitant septal myectomy with surgical aortic valve replacement. Methods: We reviewed 21 patients who underwent surgical aortic valve replacement and concomitant septal myectomy from April 2014 to September 2019. The global and regional left ventricular ejection fraction changes between the perioperative periods were analyzed using two-dimensional speckle-tracking echocardiography. The resected myocardium was pathologically assessed. Results: No operative mortality was observed during the study period. Transthoracic echocardiography showed no significant differences in preoperative and postoperative left ventricular ejection fraction (68.1 ± 9.9% vs. 68.6 ± 6.0%, p = 0.82) or interventricular septum thickness (11.9 ± 1.4 mm vs. 11.5 ± 1.5 mm, p = 0.23). Interventricular septum thickness at the end-systolic phase, which is the maximum septal wall thickness, was significantly reduced postoperatively (27.7 ± 9.3 mm vs. 22.6 ± 5.5 mm, p &lt; 0.05). The basal, mid, and apical septal areas improved with septal myectomy by 80%, 230%, and 27%, respectively, compared to perioperative echocardiography (basal septal, 80 ± 23%; mid septal, 230 ± 830%; apical septal, 27 ± 350%). Pathological examination of the resected myocardium revealed marked endocardial thickness (mean, 914 µm) with focal fibrosis. Conclusions: In aortic valve stenosis patients with septal hypertrophy, concomitant septal myectomy with surgical aortic valve replacement improved regional myocardial function and eliminated left ventricular outflow tract obstruction by removing thickened endocardium and prominent fibrosis.

Electrocardiographic Patterns and Ejection Fraction in Patients with Nonischemic Dilated Cardiomyopathy: A Cross-sectional Retrospective Study

Background:: The relationship between ECG changes in dilated nonischemic cardiomyopathy and ejection fraction (EF) is complex and poorly understood. Thus, this study aimed to identify the most common patterns of ECG associated with dilated nonischemic cardiomyopathy and their relationship to EF. Methods:: A retrospective cross-sectional study was conducted between 2019 and 2022, including 100 consecutive patients with nonischemic dilated cardiomyopathy. ECG data were rate, axis, left (LBBB) and right bundle branch block (RBBB), first-degree heart block, premature ventricular contractions, depth of S wave in leads V1 and V2, length of R wave in leads V2 and V6, the ratio of R/S in the lead V4, left ventricular hypertrophy (LVH), maximum R wave length in leads I, II, and III, poor R wave progression, ST-segment elevation, and T wave inversion. Results:: The most common ECG pattern associated with cardiomyopathy was T-wave inversion (47%). The EF was 23.9± 8.87% in patients with LBBB and 25.5± 8.07% in patients without LBBB (P= 0.361). In patients with T-wave inversion, the EF was 23.4± 8.21%, and it was 26.28± 8.35% in patients without T-wave inversion (P= 0.086). In patients with LVH, the EF was 23.89± 7.84%, and it was 25.5± 8.66% in patients without LVH (P= 0.354). A negative nonsignificant correlation existed between SV1, SV2, RV2, RV6, R/S V4, and maximum R in I, II, III, and EF. Conclusions:: The study showed that T-wave inversion was the most common pattern associated with dilated nonischemic cardiomyopathy. The study provided insight into the negative correlation between EF and SV1, SV2, RV2, RV6, R/S V4, and maximum R in I, II, and III, although it did not reach a significant level.

Anti-Oxidized Self-Assembly of Multilayered F-Mene/MXene/TPU Composite with Improved Environmental Stability and Pressure Sensing Performances.

MXenes, as emerging 2D sensing materials for next-generation electronics, have attracted tremendous attention owing to their extraordinary electrical conductivity, mechanical strength, and flexibility. However, challenges remain due to the weak stability in the oxygen environment and nonnegligible aggregation of layered MXenes, which severely affect the durability and sensing performances of the corresponding MXene-based pressure sensors, respectively. Here, in this work, we propose an easy-to-fabricate self-assembly strategy to prepare multilayered MXene composite films, where the first layer MXene is hydrogen-bond self-assembled on the electrospun thermoplastic urethane (TPU) fibers surface and the anti-oxidized functionalized-MXene (f-MXene) is subsequently adhered on the MXene layer by spontaneous electrostatic attraction. Remarkably, the f-MXene surface is functionalized with silanization reagents to form a hydrophobic protective layer, thus preventing the oxidation of the MXene-based pressure sensor during service. Simultaneously, the electrostatic self-assembled MXene and f-MXene successfully avoid the invalid stacking of MXene, leading to an improved pressure sensitivity. Moreover, the adopted electrospinning method can facilitate cyclic self-assembly and the formation of a hierarchical micro-nano porous structure of the multilayered f-MXene/MXene/TPU (M-fM2T) composite. The gradient pores can generate changes in the conductive pathways within a wide loading range, broadening the pressure detection range of the as-proposed multilayered f-MXene/MXene/TPU piezoresistive sensor (M-fM2TPS). Experimentally, these novel features endow our M-fM2TPS with an outstanding maximum sensitivity of 40.31 kPa-1 and an extensive sensing range of up to 120 kPa. Additionally, our M-fM2TPS exhibits excellent anti-oxidized properties for environmental stability and mechanical reliability for long-term use, which shows only ~0.8% fractional resistance changes after being placed in a natural environment for over 30 days and provides a reproducible loading-unloading pressure measurement for more than 1000 cycles. As a proof of concept, the M-fM2TPS is deployed to monitor human movements and radial artery pulse. Our anti-oxidized self-assembly strategy of multilayered MXene is expected to guide the future investigation of MXene-based advanced sensors with commercial values.

Changes in Soil Phosphorus Fractions and their Relationships with Selected Soil Properties After 14 Years of Combined Fertilization and Cultivation Practices in a Sloping Cropland with Entisols

Changes in Soil Phosphorus Fractions and their Relationships with Selected Soil Properties After 14 Years of Combined Fertilization and Cultivation Practices in a Sloping Cropland with Entisols

A Comparison of the Association of Septal Scar Burden on Responses to LBBAP-CRT and BVP-CRT

BackgroundLeft bundle branch area pacing (LBBAP) is an alternative to biventricular pacing (BVP) for cardiac resynchronization therapy (CRT). However, despite the presence of left bundle branch block, whether cardiac substrate may influence the effect between the 2 strategies is unclear. ObjectivesThis study aims to assess the association of septal scar on reverse remodeling and clinical outcomes of LBBAP compared with BVP. MethodsWe analyzed patients with nonischemic cardiomyopathy who had CRT indications undergoing preprocedure cardiac magnetic resonance examination. Changes in left ventricular ejection fraction (LVEF) and echocardiographic response (ER) (≥5% absolute LVEF increase) were assessed at 6 months. The clinical outcome was the composite of all-cause mortality, heart failure hospitalization, or major ventricular arrhythmia. ResultsThere were 147 patients included (51 LBBAP and 96 BVP). Among patients with low septal scar burden (below median 5.7%, range: 0% to 5.3%), LVEF improvement was higher in the LBBAP than the BVP group (17.5% ± 10.9% vs 12.3% ± 11.8%; P = 0.037), with more than 3-fold increased odds of ER (OR: 4.35; P = 0.033). In high sepal scar subgroups (≥5.7%, range: 5.7%-65.9%), BVP trended towards higher LVEF improvement (9.2% ± 9.4% vs 6.4% ± 12.4%; P = 0.085). Interaction between septal scar burden and pacing strategy was significant for ER (P = 0.002) and LVEF improvement (P = 0.011) after propensity score adjustment. During median follow-up of 33.7 (Q1-Q3: 19.8-42.1) months, the composite clinical outcome occurred in 34.7% (n = 51) of patients. The high-burden subgroups had worse clinical outcomes independent of CRT method. ConclusionsRemodeling response to LBBAP and BVP among nonischemic cardiomyopathy patients is modified by septal scar burden. High septal scar burden was associated with poor clinical prognosis independent of CRT methods.

The Dominant Role of Recrystallization and Grain Growth Behaviors in the Simulated Welding Heat-Affected Zone of High-Mn Steel.

Single-pass-welding thermal cycles with different peak temperatures (Tp) were reproduced by a Gleeble 3800 to simulate the heat-affected zone (HAZ) of a Fe-24Mn-4Cr-0.4C-0.3Cu (wt.%) high manganese austenitic steel. Then, the effect of Tp on the microstructure and mechanical properties of the HAZ were investigated. The results indicate that recrystallization and grain growth play dominant roles. Based on this, the HAZ is proposed to categorize into three zones: the recrystallization heat-affected zone (RHAZ) with a Tp of 700~900 °C, the transition heat-affected zone (THAZ) with a Tp of 900~1000 °C, and the coarse grain heat-affected zone (CGHAZ) with a Tp of 1000~1300 °C. The recrystallization fraction was 29~44% in the RHAZ, rapidly increased to 87% in the THAZ, and exceeded 95% in the CGHAZ. The average grain size was 17~19 μm in the RHAZ, slightly increased to 22 μm in the THAZ, and ultimately increased to 37 μm in the CGHAZ. The yield strength in the RHAZ and THAZ was consistent with the change in recrystallization fraction, while in the CGHAZ, it satisfied the Hall-Petch relationship with grain size. In addition, compared with the base material, the Charpy impact absorbed energy at -196 °C decreased by 22% in the RHAZ, but slightly increased in the CGHAZ. This indicates that the theory of fine grain strengthening and toughening is not entirely applicable to the HAZ of the investigated high-Mn steel.

Evaluating the Effects of Time From Brain Death and Type of Inotrope Usage on Result of Heart Transplant: Results of 1-Year Follow-Up.

Heart transplant is the most effective treatment in patients with advanced heart failure who are refractory to medical treatment. The brain death interval and type of inotrope We assessed the effects of these parameters on heart transplant outcomes. In this follow-up study, we followed heart transplant recipients for 1 year to study patient survival, ejection fraction, adverse events, and organ rejection. We evaluated follow-up results on time from brainstem death test to the cross-clamp placement, as well as the type of inotrope used. Our study enrolled 54 heart transplant candidates. The inotrope dose was 3.66 ± 0.99 μg/kg/min, and the most used inotrope, with 28 cases (51.9%), was related to dopamine. Six cases (11.1%) of death and 1 case of infection after transplant were observed in recipients. The average ejection fraction of transplanted hearts before transplant, instantly at time of transplant, and 1 month, 6 months, and 1 year after transplant was 54.9 ± 0.68, 52.9 ± 10.4, 51.9 ± 10.7, 50.1 ± 10.9, and 46.8 ± 17, respectively; this decreasing trend over time was significant (P =.001). Furthermore, ejection fraction changes following transplant did not differ significantly in transplanted hearts regarding brain death interval and type of inotrope used. Our study revealed that cardiac output of a transplanted heart may decrease over time and the time elapsed from brain death, and both dopamine and norepinephrine could have negligible effects on cardiac function.

Effects of cooling process on the microstructure and mechanical properties of a novel high-V high-Mn TWIP steel for cryogenic storage tank applications

In the present work, a novel high-V high-Mn twinning induced plasticity (TWIP) steel for cryogenic storage tank applications was developed. Furthermore, innovative two-stage cooling processes encompassing ultra-fast cooling and the subsequent furnace cooling were proposed. Effects of cooling process on the microstructure and mechanical properties of the experimental steel were investigated. It was observed that with the change in cooling process (the initial temperature of furnace cooling rised gradually), the dwell time of hot-rolled plates above 600 °C was extended. The extension in dwell time facilitated the precipitation of secondary phase particles, leading to the change in average diameter and volume fraction of secondary phase particles. The yield strength increased with the increasing initial temperature of furnace cooling due to the combined effect of small-sized secondary phase particles inside the grains and large-sized ones located at the grain boundaries. The occurrence of intergranular cracking, primarily caused by the presence of large-sized secondary phase particles at the grain boundaries, was the main factor responsible for the significant reduction in total elongation. The small-sized secondary phase particles inside the grains inhibited deformation twinning, while the large-sized ones at the grain boundaries weaken the binding force between grain boundaries, which ultimately resulted in a decrease in cryogenic impact toughness. The implementation of two-stage cooling processes effectively mitigated the trade-off between yield strength and cryogenic impact toughness, offering a novel approach and valuable insights for optimizing the strength and toughness characteristics of cryogenic high-Mn steels.

Protein Kinase C Beta II Inhibitor Conjugated with Myristic Acid and Trans-Activator of Transcription improves intracellular delivery and cardiovascular protection in porcine myocardial ischemia/reperfusion injury

Introduction: While timely reperfusion of oxygenated blood is critical during resuscitation of ischemic myocardium, oxidative stress during reperfusion still leads to ischemia/reperfusion (I/R) injury and ultimately, cardiomyocyte death. The major sources of oxidative stress targeted in this study are NADPH oxidase (NOX-2) and mitochondria, which are both activated by protein kinase C beta II (PKCβII). In previous studies with an ex-vivo rat heart I/R model, Myristic Acid (Myr) and Trans-Activator Transcription (Tat; YGRKKRRQRRR) conjugated PKCβII inhibitor (Myr-Tat-PKCβII-; N-Myr-Tat-CC-SLNPEWNET) showed cardioprotective effects and decreased infarct size. In this study, we hypothesized that Myr-Tat-PKCβII- will offer cardioprotective effects in comparison with a scrambled peptide control (Myr-Tat-PKCβII-scram; N-Myr-Tat-CC-WNPESLNTE) in an in-vivo porcine myocardial I/R model. Methods: Regional I(1 hour)/R(3 hours) was induced in Male Yorkshire pigs (38-50kg) by inflating a balloon to occlude the Left Anterior Descending Artery (LAD) at the level of the second diagonal branch (supplies 40% of anterior left ventricle) and then deflating it to allow for reperfusion. Then, a bolus of either Myr-Tat-PKCβII- or Myr-Tat-PKCβII-scram (20ng/kg; ~100pmol in blood) was immediately administered into the LAD. Cardiac function and injury were measured by monitoring changes in ejection fraction (EF) and through routine measurements of serum creatine phosphokinase (CPK), troponin I, and myoglobin, respectively. After I/R, the hearts were stained with 1% Evans Blue dye to identify the area at risk (AR) and 1% triphenyltetrazolium chloride to determine the area of necrosis (AN). Infarct size was then quantified (AN/AR) and all data was analyzed via Student’s t-test. Results: Analysis showed that Myr-Tat-PKCβII- significantly restored EF to within 1.40.7% of baseline compared to controls which only restored EF to within 6.42.1% (p&lt;0.05) of baseline EF. Myr-Tat-PKCβII- showed a significant increase in serum myoglobin levels at 1 hr of reperfusion (1362.1 83.4 μg/mL, n=4) compared to scrambled control (202.1197.3 μg/mL, n=3 p&lt;0.05). Myr-Tat-PKCβII- reduced infarct size to 10.0±2.8%; n=4; compared to scrambled control hearts (28.5±8.3%; n=6; p&lt;0.05). CPK and Troponin I levels were comparable in both groups. These results suggest that Myr-Tat-PKCβII- can help prevent cardiac injury when given immediately after an ischemic event. Conclusions: Data from ex-vivo rat heart I/R model, coupled with data from this in-vivo porcine myocardial I/R model indicate the effcacy of Myr-Tat-PKCβII- in preventing oxidative stress-induced myocardial I/R injury when given at the beginning of reperfusion. These findings suggest that Myr-Tat-PKCβII- could be useful in the clinical setting when administered immediately after cardiac resuscitation. Future studies include the treatment of rat cardiomyocyte cells with Myr-Tat-PKCβII- prior to 24 hr hypoxia/24 hr reoxygenation, followed by cell viability assays compared to untreated control. This additional data can help determine the optimal dose to use in a 12 week survival study using the same porcine myocardial I/R protocol. Funding: This study was funded by the Philadelphia College of Osteopathic Medicine, Department of Biomedical Sciences, Division of Research, and the Center for Chronic Diseases of Aging, the National Heart, Lung &amp; Blood Institute at NIH (grant # 1R43HL160338-01) and Young Therapeutics, LLC. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effects of viscosity and launch pressure on variations of the maximum impact acceleration in cross media water-entry process

The aim of the investigation was to experimentally discuss effects of viscosity and launch pressure on variations of the maximum impact acceleration in cross media water-entry process. For different launch pressures, they reflected effects of motion peculiarity. They were 2.5MPa, 2.75MPa, and 3.0MPa. Variations of viscosity explained influences of property of operating environment. Via the change of lithium bromide solution mass fraction, various viscosities were got. The mass fractions employed were 1%, 2%, and 3%. Results indicated that the maximum impact acceleration grew steadily with the increment of lithium bromide solution viscosity. When launch pressure grew, the maximum impact acceleration increased gradually. Comprehensively, effect degree of viscosity was more intense than that of the launch pressure.

FEATURES OF LIPID METABOLISM DISORDERS IN INDIVIDUALS WITH GENETIC PREDISPOSITION TO ARTERIAL HYPERTENSION AND PATIENTS WITH ESSENTIAL ARTERIAL HYPERTENSION

Objective: To determine the peculiarities of lipid metabolism indicators’ changes in healthy individuals with a genetic predisposition to arterial hypertension (AH) and patients with essential arterial hypertension (EAH). Design and method: 231 patients with second stage of EAH (105 men and 126 women; average age was 52.3±1.2 years) were examined. The duration of EAH was 9.7±0.45 years. 121 of them had a concomitant stable coronary artery disease (CAD). The control group included 30 healthy people of similar age and gender. A comparison group consisted of 23 healthy individuals with a AH family history. Additionally to lipid spectrum, levels of lipoprotein (a) (Lp(a)), apolipoprotein B100 (apoB100) and apolipoprotein A-1 (apoA-1) were determined. Statistical calculations were performed using Statistica for Windows 10.0. Results: Patients with genetic predisposition to AH had similar to indicators in patients with II EAH stage proatherogenic changes in lipid fractions. Their Lp(a) levels increased to 29.9 (24.5; 32.1) mg/dl, which is 67.0% higher than the levels in the control group (p=0.0005). Levels of apolipoproteins (apoB100 and apoA1) in the serum of healthy persons with AH predisposition did not differ from the control group. Patients with stage II EAH showed an increase in proatherogenic fractions of lipoproteins, apoB100, Lp(a), and a decrease in high-density lipoprotein cholesterol (HDL-C) and apoA-1 compared to control (p&lt;0.0001). Analysis of lipid indicators in patients with concomitant CAD compared to patients without CAD revealed no significant differences between these two groups, except of increasing in the Lp(a) level by 24.4% (p&lt;0.05). A significant positive correlations were found between the Lp(a) level with both the sum of scores on the SCORE scale and the CAD presence (r=0.25 and r=0.35, p=0.002), respectively. Conclusions: The lipid metabolism disorders in people with determinism for AH begin even before an increase in blood pressure and are genetically determined. The addition of hypertension contributes to the further progression of lipid metabolism disorders. The obtained data indicate the high prognostic significance of Lp(a) in patients with EAH in the development and establishment of both hypertension itself and CAD and increasing of patients’ cardiovascular risk.

Microtubules distinctly contribute to the performance of the healthy and pressure-overloaded RV

Introduction: Microtubules (MT) are a key contributor to cardiomyocyte contractility and mechanics. Recently, our group reported that acute depolymerization of MT reduces viscosity and elasticity and alters anisotropy of healthy and pressure-overloaded right ventricular (RV) tissues. While RV free wall viscosity and elasticity are distinctly upregulated with chronic pressure overload, how organ function is affected by viscoelastic contribution of the MT remains unknown. Our aim was to investigate the role of MT polymerization in RV function from its effect on RV tissue viscoelasticity. We hypothesized that the MT differentially contributes to healthy and pressure-overloaded RV function. Methods: All procedures and methods were approved by Colorado State University IACUC. Pulmonary hypertension (PH) was induced in 6-week-old male rats via 3-week monocrotaline treatment. Healthy age- and sex-matched rats served as control. Pressure-volume (PV) relationships were obtained by RV catheterization before and after intramyocardial injections of 0.3mM colchicine (COL) to acutely depolymerize the MT network and reduce tissue viscoelasticity. Functional impacts were evaluated by monitoring changes in RV end-systolic pressure (ESP), cardiac output (CO), stroke volume (SV), ejection fraction (EF), dP/dt max and min, cardiac effciency (CE), and the end-systolic pressure-volume relation (ESPVR). Results: As expected, monocrotaline treatment induced marked PH and RV contractile dysfunction, indicated by a significant elevation of RV ESP with reduced CO and ESPVR. In the healthy RV, COL treatment led to marked reductions in all functional parameters, indicating that the MT network is critical to maintain RV performance and contractile function in the healthy heart. In the pressure-overloaded RV, COL treatment similarly reduced SV, CO, EF, and dP/dt max and min, but increased CE and ESPVR, indicating that MT depolymerization improved mechanical effciency and contractility. To rule out effects caused by bolus injections alone, we administered a similar quantity of saline and observed no effects on the PV parameters in healthy RV. Discussion: Our study is the first to investigate the acute effect of MT depolymerization on RV function in healthy and diseased states. We found distinct contributions of MT to the contractile function and mechanical effciency of healthy and pressure-overloaded RVs. These findings reveal a critical influence of tissue viscoelasticity on RV physiology and dysfunction, emphasizing the importance of considering myocardial viscoelastic behavior in future studies investigating cardiac remodeling and heart failure pathophysiology. This work is partially supported by the National Science Foundation (NSF) grant 2244994. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.