Decrease In Wall Thickness Research Articles

Effect of wall thickness on the precipitation behavior, microstructure, electrical conductivity and mechanical properties of CuCrZr alloy prepared by electron beam powder bed fusion (EB-PBF)

Electron beam powder bed melting (EB-PBF) is one of the most promising technologies for preparing thin-walled CuCrZr alloys, because CuCrZr alloys have a high energy absorption rate for electron beams, and high preheating temperature can reduce the solidification temperature gradient and reduce the deformation of thin-walled parts. At present, there are few reports on the systematic research work on the EB-PBF of thin-walled CuCrZr alloy parts, and it's impossible to effectively supervise the production of complex thin-walled CuCrZr parts. This work aims to investigate the effect of thickness on the microstructure and mechanical properties of CuCrZr alloys produced by EB-PBF. As the wall thickness decreases from 5.0 mm to 0.3 mm, the grain sizes of the XY and YZ planes decreased from 20.41 μm and 43.06 μm to 14.49 μm and 21.53 μm respectively, and the texture intensity decreased from 16.04 and 23.57 to 7.62 and 10.99. The analysis showed that Cr2O3 nanoprecipitates were precipitated in situ in the sample, and their average size decreased from 65.82 nm to 21.59 nm. Due to the reduction in grain and nanoprecipitate size, the performance of thin-walled samples is significantly enhanced, with YS increasing from 112 MPa to 165 MPa and conductivity increasing from 71.7 %IACS to 86.1 %IACS. Finally, the main contributions to the yield strength (YS) of specimens with different wall thicknesses was discussed. Precipitation strengthening and dislocation strengthening are the main strengthening mechanisms in thin-walled samples, and the gradual refinement of nano-precipitates is the main reason for the improvement of mechanical properties as the wall thickness decreases.

Precontouring as a Tool to Improve the Laser Powder Bed Fusion Printability of Inconel939 Thin Walls

This work investigates the influence of adding a contour scan prior to hatching (precontouring) on the printability of Inconel 939 thin‐wall sections produced by laser powder bed fusion. Walls with thicknesses ranging from 500 to 1500 μm, manufactured with two hatch scanning parameter sets that give rise to different microstructures and very high density in bulk samples of the same alloy, are investigated. It is shown that, while the texture as well as the grain size and shape is only influenced moderately by the contour scanning strategy, precontouring does lead to a significant reduction of the melt pool depth, an effect that is increasingly pronounced with decreasing wall thickness. This work highlights the role of the precontour scan as a heat sink, shifting the normalized enthalpy input toward lower values and thus limiting the accumulation of excess heat. Precontouring is put forward as a scanning strategy to improve the manufacturability of thin sections.

Association between Long-Term Exposure to Traffic-Related Air Pollution and Cardio-Metabolic Phenotypes: An MRI Data-Based Analysis.

Long-term exposure to traffic-related air pollution (TRAP) is associated with cardiometabolic disease; however, its role in subclinical stages of disease development is unclear. Thus, we aimed to explore this association in a cross-sectional analysis, with cardiometabolic phenotypes derived from magnetic resonance imaging (MRI). Phenotypes of the left (LV) and right cardiac ventricle, whole-body adipose tissue (AT), and organ-specific AT were obtained by MRI in 400 participants of the KORA cohort. Land-use regression models were used to estimate residential long-term exposures to TRAP, e.g., nitrogen dioxides (NO2) or particle number concentration (PNC). Associations between TRAP and MRI phenotypes were modeled using linear regression. Participants' mean age was 56 ± 9 years, and 42% were female. Long-term exposure to TRAP was associated with decreased LV wall thickness; a 6.0 μg/m3 increase in NO2 was associated with a -1.9% [95% confidence interval: -3.7%; -0.1%] decrease in mean global LV wall thickness. Furthermore, we found associations between TRAP and increased cardiac AT. A 2,242 n/cm3 increase in PNC was associated with a 4.3% [-1.7%; 10.4%] increase in mean total cardiac AT. Associations were more pronounced in women and in participants with diabetes. Our exploratory study indicates that long-term exposure to TRAP is associated with subclinical cardiometabolic disease states, particularly in metabolically vulnerable subgroups.

Functional cardiac consequences of β-adrenergic stress-induced injury in a model of Duchenne muscular dystrophy.

Cardiomyopathy is the leading cause of death in Duchenne muscular dystrophy (DMD); however, in the mdx mouse model of DMD, the cardiac phenotype differs from that seen in DMD-associated cardiomyopathy. Although some have used pharmacologic stress to stimulate injury and enhance cardiac pathology in the mdx model, many methods lead to high mortality with variable cardiac outcomes, and do not recapitulate the structural and functional cardiac changes seen in human disease. Here, we describe a simple and effective method to enhance the cardiac phenotype model in mdx mice using advanced 2D and 4D high-frequency ultrasound to monitor cardiac dysfunction progression in vivo. mdx and wild-type mice received daily low-dose (2 mg/kg/day) isoproterenol injections for 10 days. Histopathological assessment showed that isoproterenol treatment increased myocyte injury, elevated serum cardiac troponin I levels and enhanced fibrosis in mdx mice. Ultrasound revealed reduced ventricular function, decreased wall thickness, increased volumes and diminished cardiac reserve in mdx compared to wild-type mice. Our findings highlight the utility of challenging mdx mice with low-dose isoproterenol as a valuable model for exploring therapies targeting DMD-associated cardiac pathologies.

Upregulation of Angiomotin-Like 2 Ameliorates Experimental Pulmonary Arterial Hypertension by Inactivating YAP1 Signaling.

Angiomotin-like 2 (AMOTL2) is related to numerous physiological and pathological conditions by affecting signal transduction. However, whether AMOTL2 is linked to pulmonary arterial hypertension (PAH) has not been addressed. This work aimed to investigate the potential role of AMOTL2 in PAH. A decrease in AMOTL2 abundance was observed in the lungs of PAH rats. The upregulation of AMOTL2 significantly decreased right ventricle systolic pressure and right ventricular hypertrophy in PAH rats. Overexpression of AMOTL2 also led to a noteworthy decrease in vascular wall thickness, pulmonary artery area, and collagen deposition in rats with PAH. AMOTL2 was downregulated in hypoxia-stimulated pulmonary arterial smooth muscle cells (PASMCs). Moreover, AMOTL2 overexpression impeded hypoxia-evoked proliferation, migration, and phenotypic transformation in rat PASMCs. Mechanistic investigation revealed that Yes-associated protein 1 (YAP1) activation in PAH rats or hypoxia-stimulated PASMCs was markedly inhibited by AMOTL2 overexpression, which was associated with increased large tumor suppressor 1/2 phosphorylation. The inhibition of large tumor suppressor 1/2 reversed the AMOTL2-mediated inactivation of YAP1. Restoring the activity of YAP1 reversed the inhibitory effect of AMOTL2 on hypoxia-evoked proliferation, migration, and phenotypic transformation of PASMCs. Collectively, these results suggest that AMOTL2 can ameliorate PAH in a rat model by interfering with pulmonary arterial remodeling via the inactivation of YAP1 signaling. Our work indicates that AMOTL2 may be a candidate target for novel drug development for the treatment of PAH.

Vascular tissues bioprinted with smooth muscle cell-only bioinks in support baths mimic features of native coronary arteries

This study explores the bioprinting of a smooth muscle cell-only bioink into ionically crosslinked oxidized methacrylated alginate (OMA) microgel baths to create self-supporting vascular tissues. The impact of OMA microgel support bath methacrylation degree and cell-only bioink dispensing parameters on tissue formation, remodeling, structure and strength was investigated. We hypothesized that reducing dispensing tip diameter from 27 G (210μm) to 30 G (159μm) for cell-only bioink dispensing would reduce tissue wall thickness and improve the consistency of tissue dimensions while maintaining cell viability. Printing with 30 G tips resulted in decreased mean wall thickness (318.6μm) without compromising mean cell viability (94.8%). Histological analysis of cell-only smooth muscle tissues cultured for 14 d in OMA support baths exhibited decreased wall thickness using 30 G dispensing tips, which correlated with increased collagen deposition and alignment. In addition, a TUNEL assay indicated a decrease in cell death in tissues printed with thinner (30 G) dispensing tips. Mechanical testing demonstrated that tissues printed with a 30 G dispensing tip exhibit an increase in ultimate tensile strength compared to those printed with a 27 G dispensing tip. Overall, these findings highlight the importance of precise control over bioprinting parameters to generate mechanically robust tissues when using cell-only bioinks dispensed and cultured within hydrogel support baths. The ability to control print dimensions using cell-only bioinks may enable bioprinting of more complex soft tissue geometries to generatein vitrotissue models.

Effect of rapid cooling, frozen storage, and thawing on the passive viscoelastic properties and structure of the rat aorta

Biological tissues decay over time after harvesting, which alters their biomechanical properties. This poses logistical challenges for studies investigating passive arterial biomechanics as tissues need to be characterized shortly after excision. Freezing and cryopreservation methods can help alleviate the need for biomechanical testing of fresh tissue in human ex vivo studies. However, these methods tend to eliminate or reduce arterial cell functionality and affect passive biomechanics. Furthermore, their impact on dynamic arterial biomechanics remains unknown despite arterial viscoelastic properties being an integral component contributing to arterial stiffness under in vivo loading conditions. The present study aims to investigate the impact of rapid cooling and subsequent storage at −80 °C on the passive viscoelastic properties of arterial tissue and aid in ascertaining whether this is a suitable method to delay tissue analysis for studies investigating passive arterial biomechanics. Control and frozen abdominal rat aorta segments were quasi-statically and dynamically tested using a biaxial testing set-up. The results were modeled using a constituent-based quasi-linear viscoelastic modeling framework, yielding directional stiffness parameters, individual constituent biomechanical contributions, and a quantification of viscoelastic stiffening under dynamic pressurization conditions. Frozen samples displayed significantly decreased wall thickness, viscoelastic dissipation, viscoelastic stiffening, and significantly decreased circumferential deformation with changes in luminal pressure. Furthermore, frozen samples displayed significantly increased circumferential stiffness, pulse wave velocity, and collagen load bearing. Consequently, these changes should be considered when utilizing this tissue preservation method to delay biomechanical characterization of rat aortic tissue.

Long-term intermittent fasting induces sex-dependent changes in small intestine from SAMP8 aged mice

Background: Intermittent fasting (IF) is a popular and effective method to decrease body weight. Yet, the effects of IF on aged intestine is unknown. SAMP8 (Senescence Accelerated Mouse-Prone 8) mice are used as a model for studying aging. This study aimed to examine the potential for IF to ameliorate age-associated disturbances in murine jejunum. Methods: Two-month-old male and female SAMP8 mice were randomly assigned to either an IF protocol or an ad-libitum diet (AL) for the 8-month study (n=7-10 group). Fasted mice followed a 24-hour alternate day fasting protocol. At the end of the study mice were euthanized and jejunum stored at −80°C until use for western blot or other assay, and a segment was fixed for histology. Results: IF resulted in significantly less weight gain in both males (22% less, n=7-10, p<0.05) and females (33% less, n=7-8, p<0.05) and response to glucose load (glucose tolerance testing) was comparable in both sexes: area under curve for AL > IF. Interestingly, IF significantly reduced fasting serum glucose levels in males (30% less, n=6, p<0.05), but IF had no effect on fasting serum glucose in females. In jejunum, we assessed: protein expression, health, and morphology. In females, IF led to a 57% decrease in GLUT2 expression (n=5-6, p<0.05) versus AL. GLUT2 moves glucose/galactose and fructose out of the enterocyte into the blood, suggesting restructuring of monosaccharide transport due to IF. IF had no effect on jejunum GLUT5 or SGLT1 expression. Cleaved Caspase-3 expression was decreased by IF in both sexes versus AL. This reduction was greater in females, suggesting a sex-dependent protective role of IF against apoptosis. Moreover, IF induced a significant increase 1.4-fold (n=5=6, p<0.05) in jejunum superoxide dismutase (SOD) activity in both sexes. Jejunum morphology was significantly changed in females only: IF induced both a decrease in villi length (by 21%, n=4/group, p<0.05) and a decrease in wall thickness (by 7%, n=4/group, p<0.05). Conclusions: In both sexes, IF decreased body weight, yet in females resting glucose levels were unchanged by IF. In females, IF reduced monosaccharide absorption out of intestines, yet improved overall intestinal health, increasing antioxidant levels with SOD. These findings collectively highlight the complex effects of IF on cellular processes and demonstrate significant sex-dependent aged intestinal responses. Unraveling the underlying molecular mechanisms driving these sex-dependent IF-induced effects is currently under evaluation. Midwestern-Arizona Alzheimer’s Consortium Grant, Midwestern University Intramural Grant. 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.

Streptococcus pneumoniae infection promotes the long-term development of an atherosclerotic phenotype in atheroprone ApoE-deficient mice

Background: Epidemiological studies have identified pneumonia to be closely linked to an increased risk for cardiovascular events. Potential causality of this association, however, remains to be established, and underlying mechanisms are yet to be resolved. Here, we tested the hypothesis that prior pulmonary infection with Streptococcus pneumoniae accelerates the development of an atherosclerotic phenotype in mice. Such a phenotype would explain the increased cardiovascular risk in the epidemiological data. Methods: Atheroprone ApoE−/− mice were fed a high fat diet, and after 6 weeks nasally infected with either 2.5 x 107 S. pneumoniae or vehicle control. Antibiotic therapy was initiated 60h post infection (p.i.) by s.c. injections of ampicillin on 5 consecutive days followed by oral administration of amoxicillin for 10 days. At days 35 or 90 post-infection, aortas were harvested and assessed for vasoreactivity and arterial stiffness by wire myography. Morphological changes of the aortic vessel wall and eNOS expression levels were quantified by western blot and histological stainings. Results: Unexpectedly, 35 days p.i. aortas of infected mice presented with decreased aortic stiffness, increased endothelial-independent vasorelaxation and decreased wall thickness due to lower collagen-1 expression and reduced elastin fragmentation when compared to sham animals. After 90 days, however, these effects had reversed and animals with prior pneumonia showed increased aortic stiffness, attenuated endothelial dependent vasorelaxation that was associated with reduced eNOS protein expression and phosphorylation, and increased atherosclerotic plaque burden relative to vehicle control. Conclusion: Single episodes of pneumonia promote a delayed pro-atherogenic phenotype that manifests as endothelial dysfunction, aortic stiffening and enhanced plaque burden. Underlying mechanisms are currently under investigation to identify risk predictors for patient stratification and clinical targets for prevention of cardiovascular disease following pneumonia. Funding: German Ministry of Education and Research (BMBF) in the framework of SYMPATH (01ZX1906A). 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.

Abstract 3092: Smooth Muscle Cell Tgf-β Receptor Knockout Improves Arteriovenous Fistula Maturation Via Attenuation Of Autophagy

Objectives: Arteriovenous fistulae (AVF) are the preferred vascular access for patients with end-stage renal disease (ESRD) but have high rates of primary failure. Models of AVF using mice with chronic kidney disease (CKD) show diminished maturation and increased failure compared to AVF using wild type mice. Since mice with CKD show increased TGF-β1 expression and activity in the AVF model, and TGF-β1 signaling can alter autophagy, we hypothesized that CKD increases autophagy during AVF maturation, whereas inhibition of the smooth muscle cell (SMC) TGF-β receptor would attenuate autophagy and promote AVF maturation. Methods: An aortocaval fistula or sham procedure was created in mice that had CKD induced by 5/6 nephrectomy (5/6 Nx) or sham nephrectomy (0/6 Nx). Myh11-CreER T2 ; Tgfbr1 fl/fl ; Tgfbr2 fl/fl ; mT/mG mice (TGFβRI II-KO) and control C57BL/6J mice were used. The diameter of the IVC was determined using ultrasound at days 0, 7, 14, and 21. AVF were harvested at day 7 or 21 for histology and immunoreactivity. Deidentified human AVF and control vein specimens were collected for analysis from second stage basilic vein transpositions. Results: In C57BL/6J mice, AVF had significantly decreased diameter (p=0.0051), increased wall thickness (p=0.0002), as well as increased immunoreactivity of collagen-1 (p=0.0163), collagen-3 (p=0.0029), TGF-β1 (p=0.0184) and fibronectin (p=0.00321) in mice with CKD compared to control mice (n=6). SMC showed increased markers of autophagy (LC3B and P62) in mice with CKD compared to control mice (LC3B, p<0.0001; P62, p=0.006; n=6); similarly, autophagy makers were increased in human AVF compared with the control veins (LC3B, p=0.0023; P62, p=0.006; n=6). In SMC-TGFβR II-KO mice, AVF had significantly decreased wall thickness (p<0.0001), increased diameter (p=0.0258), and decreased expression of autophagy markers (LC3B, p=0.0014; P62, p=0.0046; n=6). Conclusion: CKD increases neointimal hyperplasia that is associated with increased autophagy during AVF failure, and diminished TGF-β signaling reduces autophagy and wall thickness as well as increases AVF diameter. Suppression of SMC autophagy might be a novel therapeutic approach to improve AFV function.

Detraining among Athletes-Is Withdrawal of Adaptive Cardiovascular Changes a Hint for the Differential Diagnosis of Physically Active People?

An athlete's training aims to achieve the highest possible sports results by improving physical dispositions which lead to cardiac adaptive changes. The annual training cycle is divided into periods. The preparatory period begins with gradually increasing training intensity and volume until the competitive period occurs, when the athlete's maximum performance is expected. Finally, the athlete enters a phase of loss of fitness, which is called detraining. Detraining is a time of resting both physically and mentally from the training regime and usually lasts about 4 weeks for endurance athletes. We collected data from much research on athletes' detraining. According to these data, the earliest change after detraining seems to be a decrease in left ventricular wall thickness and left ventricular mass, followed by decreased performance parameters, diastolic diameter of the left ventricle and size of the left atrium. A reversal of adaptive changes affects the left heart chamber first, then the right atrium and, finally, the right ventricle. Training reduction is often proposed as a method of differentiating an athlete's heart from cardiomyopathies. The aim of this study is to consider the diagnostic value of detraining in differentiating athletes' hearts from cardiomyopathies. We suggest that detraining cannot be conclusive in differentiating the disease from adaptive changes. Although a withdrawal of the characteristic morphological, functional and electrocardiographic changes occurs in healthy athletes during detraining, it can also concern individuals with cardiomyopathies due to the lower expression of abnormal features after decreased training loads. Therefore, a quick diagnosis and individual assessments using imaging and genetic tests are essential to recommend a proper type of activity.

Creep failure mechanism of -oriented thin-wall Ni3Al-based single crystal superalloys

Currently, thin-wall structures are widely employed in aviation engine turbine blades to enhance cooling efficiency. However, the mechanical properties of thin-walled structures exhibit significant sensitivity to thickness. This study investigates the creep behavior of a <111>-oriented Ni3Al-based single-crystal superalloy with different thicknesses (0.3, 0.5, 0.8 mm) at 1100 °C/137 MPa. The results indicate a significant reduction in creep life with a decrease in wall thickness. The mechanism of various influencing factors on different creep stages was analyzed from both microscopic and macroscopic perspectives combined with finite element modeling. The alteration in stress state from thick-wall to thin-wall influences the number of slip systems that are activated, which mainly affects the primary and steady-state creep stages. Surface oxidation as time-dependent damage leads to non-invasive crack formation, somewhat increasing the steady-state creep strain rate of thin-wall samples. The accumulation and propagation in varying wall thicknesses of cleavage microcracks primarily influence the steady-state and tertiary creep stages, respectively, thereby exacerbating the thickness debit effect.

Materials Science Analysis of RCCA Structural Materials and Calculations for Lifetime Extension

The paper considers the possibility of lifetime extending of the rod control cluster assemblies in operation by determining their residual lifetime using an approach that takes into account the actual position of the rod control cluster assembly in the core. Excessive conservatism was introduced by assuming that the immersion of the 10th working group in the core during all fuel campaigns is 70 %, while the actual position is 85-90 %. Taking into account the actual position of the rod control cluster assemblies indicates much less irradiation of the lower, most loaded part of control rod cladding and much less burnup of the 10B compared to 70 % immersion of the rod control cluster assemblies, since they are in the area of lower neutron flux density.&#x0D; The results of a comprehensive analysis of available studies and test results to determine the phenomena that can potentially approach the achievement of the boundary state of the structural components or limit the lifetime of control rods and rod control cluster assemblies in general are presented. Such phenomena include general corrosion of structural materials (42CrNiMo, Cr18Ni10Ti) (decrease in wall thickness, increased transfer of radioactive corrosion products the coolant); radiation resistance (degradation of mechanical characteristics) of control rod cladding materials (42CrNiMo) and other structural components of the rod control cluster assemblies (42CrNiMo, CrKh18Ni10Ti); radiation resistance of neutron-absorbing materials (B4C, Dy2O3∙TiO2); compatibility of absorbing materials with the control rod cladding.&#x0D; Based on the results of post-irradiation examinations of control rods tested in research reactors as dummy rods or rod control cluster assembly rods operated in the VVER-1000 core, the following boundary values were established that can be used as criteria for maintaining the integrity of the control rod cladding: maximum fast neutron fluence in the lower, most loaded part of the control rod cladding (in the weld area of the lower end plug and the cladding) should not exceed 34×1021 n/cm2; maximum burnup of the 10B isotope should not exceed 45 %. If these two criteria are met, the possibility of other potentially damaging phenomena is too low.&#x0D; According to the calculations that use the schedule of changes in the position of the rod control cluster assemblies of the control group and the power of one of the power units during one fuel cycle, one can preliminary conclude that the proposed approach will extend the lifetime of almost all rod control cluster assemblies from 25500 to 38000 hours in the automatic control group and from 75600 to 113500 hours in the shutdown group. The residual lifetime should be assessed for a particular power unit and each rod control cluster assembly separately, since each rod control cluster assembly has its own operating history.

A258 ULTRASOUND ASSESSMENT OF CROHN’S DISEASE PATIENTS FOLLOWING RISANKIZUMAB INITIATION; BASELINE, 3 AND 6 MONTH FOLLOW UP

Abstract Background Risankizumab (RIS), an interleukin-23 inhibitor specific to the p19 subunit, was approved for the treatment of moderate to severe Crohn’s Disease (CD) in December 2022. Intestinal ultrasound (IUS) is an accurate and well-tolerated modality for evaluating response to therapy. Aims We aim to assess IUS response at 3 and 6 months following RIS therapy. Methods Consecutive patients initiating RIS for CD were recruited to be evaluated by IUS at baseline (within 14 days of initiation), 3 months, and 6 months. Baseline demographics, medication exposure, surgical history, and inflammatory biomarkers were obtained. IUS response (decrease in bowel wall thickness (BWT) ≥ 25%)) and transmural remission (TR) (normalization of BWT normalization, color doppler signal (CDS, modified Limberg (ML) score 0), wall stratification, inflammatory fat) for each segment were evaluated. Paired t-tests compared values at baseline, 3 and 6 months. Results Thirty-three (20, 60.6% female) patients were recruited; 30 completed baseline and 3 month IUS, while 18 patients have 6 month IUS. Median age was 55 years (IQR 39-63), with a 12 year median CD duration (IQR 5-28). Five had inflammatory, 19 stricturing, and 6 fistulizing behaviour. CD distribution was 18 ileal, 1 colonic, and 11 ileocolonic. 20% (6/30) were bio-naïve, while 30% (9/30) had failed ≥ 3 biologics. Baseline mean CRP (4.1 ± 4.9 mg/L) did not significantly differ at 3 months (5.0 ± 6.8 mg/L, p=0.16), nor at 6 months for patients with values available (6.2mg/L ± 8.3, p = 0.38). Of patients with FC concentrations, 3 month mean FC (129.4 ±70 mcg/g) (9 patients) had significantly decreased from baseline (427.6 ± 271 mcg/g) (p=0.008), and similarly at 6 months (9 patients; baseline 396 ± 299 vs. 129 ± 75, p = 0.02). 80.0% (4/5) patients with colonic BWT ampersand:003E 3mm had IUS response (baseline mean BWT 5.6 ±1.4mm vs 3.5 ± 0.8mm at 3 months (p=0.011). IUS response was not achieved in those with ileal CD at 3 months (BWT 6.3 ± 2.1mm vs 3 month 6.0 ± 2.5mm (p=0.31). However, 21.4% (3/14) of ileal CD patients had an IUS response at 6 months. There is a non-significant ileal BWT reduction (5.4 ± 1.6mm) from baseline (6.0 ± 1.7mm) at 6 months. Of the 9 with moderate to severe CDS, 55% (5/9) had reduction to mild CDS by 3 months. TR was achieved by one patient with ileal CD at 6 months. Conclusions IUS response was achieved in 80.0% of CD patients with colonic disease at 3 months follow RIS initiation. IUS response was not detected for ileal CD at 3 months, but detected in 21.4% at 6 months A significant FC reduction by 3 and 6 months was attained. Further prospective patient recruitment and IUS at 6 and 12 months to assess preliminary results and longer-term response is needed. Funding Agencies None

P484 Intestinal Ultrasound Can Detect Active Inflammation In Inflammatory Bowel Disease Patients Despite Combined Clinical And Biomarker Remission

Abstract Background Intestinal ultrasound (IUS) has only recently been implemented in the USA for inflammatory bowel disease (IBD) monitoring. Colonoscopy is considered the gold standard for evaluation of inflammation but may not be feasible for every assessment due to cost, time, and accessibility. Clinical activity scores and biomarkers are used instead as adjunct measures of disease. Since IUS incurs low cost and time with easy accessibility, our study aimed to demonstrate the utility of incorporating IUS into IBD practice by evaluating the sensitivity and specificity of these adjunct measures of inflammation and the impact of decisions made based on IUS. Methods This retrospective cohort analysis evaluated patients with IBD at our institution who underwent IUS from July 2020 to May 2021. The patients were reviewed for repeat IUS visits until July 2022. Patients received IUS regardless of clinical or biomarker remission, and/or if they were able to receive a colonoscopy. Clinical remission was defined as UCAI ≤ 5 and partial Mayo ≤ 2 or HBI ≤ 5. Biomarker remission was defined as ESR ≤ 40 mm/hour; CRP ≤ 8 mg/L; FCP ≤ 125 mg/mg; and fecal lactoferrin ≤ 30 mcg/mL. Combined remission was defined as both clinical and biomarker remission. The sensitivity and specificity of these groups was evaluated based on IUS. Treatment plans were decided based on IUS findings. Patients with normal IUS maintained therapy while those with positive findings required a change/escalation of therapy. These patients had repeat IUS to ensure the changes resulted in reduction of inflammation. Results In 148 total patients receiving IUS, 62% (N=92) had active disease. Clinical remission (figure 1) was 41% sensitive and 75% specific while biomarker remission was 49% sensitive and 58% specific to IUS findings. When combined (clinical + biomarker remission), sensitivity increased to 62% and specificity decreased to 52% (figure 2). There was a total of 39 repeat ultrasounds. Inflammation was improved at repeat IUS, measured by a decrease in overall bowel wall thickness in 77% (30/39) patients for a mean of 0.121 cm. Vascular flow improved in 79% (15/19) of patients with abnormal Doppler at initial IUS by a mean of 0.65, and mural stratification improved in 80% (20/25) of patients with mural disruption at initial IUS. Conclusion Our study showed that even when combining biomarker results and clinical scores, the sensitivity for detecting inflammation was 62%. Additionally, as demonstrated by the improvement in inflammation at IUS follow up, clinical decisions based on IUS results effectively reduced inflammation in IBD patients. As such, IUS is necessary in the management of IBD to effectively identify and treat patients with masked inflammation.

P573 Simplified MARIA score does not predict long-term outcomes in Crohn’s disease patients undergoing modified side-to-side strictureplasty for extensive ileitis

Abstract Background Strictureplasty techniques were developed to limit the risk of short bowel syndrome in Crohn’s disease (CD) patients with affected small intestine. In the setting of extensive small bowel disease, long strictures might be treated with modified side-to-side isoperistaltic strictureplasty (SSIS). We studied long-term outcomes in patients who underwent SSIS and evaluated if radiological features on MR enterography (MRE) predict them. Methods This retrospective study included CD patients who underwent SSIS, for whom preoperative and six-month postoperative MRE were routinely performed. Simplified MARIA (MARIAs) score, considering wall thickness, edema, fat stranding and ulcers (score &amp;gt;1 active CD; maximum 5) was used. Improvement in maximal wall thickness was defined as decrease of at least 30% from baseline. Deep remission was defined as absence of symptoms and endoscopic remission (mRutgeerts score ≤i1), and clinical recurrence as occurrence of new symptoms confirmed by endoscopy (mRutgeerts score ≥i2b) or radiology (new strictures/inflammation) requiring treatment. Clinical data were collected from medical records. The correlation between recurrence and features within the MARIAs score was assessed. Results Thirty CD patients underwent SSIS and had pre- and six-month postoperative MRE (table). Immediately after surgery, 13 (43.3%) patients were continued or initiated on advanced therapy. Over a median [IQR] follow-up of 7.4 [3.3-9.3] years, 17 (56.7%) patients showed clinical recurrence of whom 6 (20.0%) needed surgical reintervention (figure). Deep remission was observed in 8 (26.7%) patients. Preoperatively, all patients had a maximum MARIAs score of 5. After surgery, the median [IQR] change in MARIAs score was 0.0 [0.0-0.8]. Cox regression analysis showed no association between decrease in overall MARIAs score, nor separate components of this score, with clinical or surgical recurrence free survival. Wall thickness decrease of &amp;gt;30%, observed in 15 (50%) patients, showed a trend for clinical recurrence free survival (p=0.098). Three patients showed normalization of MARIAs score and showed no recurrence thereafter. None of the clinical variables collected showed significant association with recurrence, except for immediate postoperative advanced therapy which had a 70% protection from clinical recurrence [p=0.036 / HR 0.3 (0.097-0.92)]. Conclusion Long-term follow-up of CD patients undergoing SSIS showed that 57% of patients had clinical recurrence and 20% needed surgical reintervention. The MARIAs score was not predictive of long-term postoperative clinical or surgical recurrence as most features of the score remained unaltered. These shortcomings of the MARIAs score should be addressed when designing improved scoring tools.

Substantial enhancement of optoelectronics and piezoelectric properties of novel hollow ZnO nanorods towards efficient flexible touch and bending sensor

The novel solid and hollow ZnO nanorods were prepared by chemical synthesis approach. The hollow ZnO NRs show a large optical band gap as compared to the solid ZnO NRs which is attributed to quantum confinement effect. The unique emission spectra of hollow ZnO NRs show an exceptional ability for visible emission as compared to solid ZnO NRs owing to unique hollow structure, which enhanced multiple scattering. The piezoelectric potential of hollow nanorod shows about 3.75 times higher peizopotential than the solid nanorods with length (a = 200 nm) and height (h = 1000 nm). The piezoelectric potential was found to be increased with the height of nanorod with a fixed length. Interestingly, the piezoelectric potential increases with decreasing wall thickness in hollow nanorod. The hollow ZnO NRs-based touch sensor shows five times higher piezoelectric response as compared to the solid ZnO NRs. These results provide valuable information for future studies aimed at improving the piezoelectric properties of hollow nanostructures for potential applications in energy harvesting and sensing.

Side chain of confined xylan affects cellulose integrity leading to bending stem with reduced mechanical strength in ornamental plants

The stem support for fresh-cut flowers exerts a profound influence on the display of their blossoms. During vase insertion, bending stems significantly affect the ornamental value, but much remains unclear about the underlying reasons. In this study, six pairs of ornamental plants were screened for the contrast of bending and straight stems. The bending stems have weakened mechanical force and biomass recalcitrance compared with the straight ones. Meanwhile, cells in the bending stems became more loosely packed, along with a decrease in cell wall thickness and cellulose levels. Furthermore, wall properties characterizations show bending stems have decreased lignocellulosic CrI and cellulose DP, and enhanced the branching ratio of hemicellulose which is trapped in the cellulose. Given the distinct cell wall factors in different species, all data are grouped in standardized to eliminate the variations among plant species. The principal composition analysis and correlation analysis of the processed dataset strongly suggest that cellulose association factors determine the stem mechanical force and recalcitrance. Based on our results, we propose a model for how branches of confined hemicellulose interacted with cellulose to modulate stem strength support for the straight or bending phenotype in cut flowers.

Investigation on thermo-hydraulic characteristic of lead–bismuth eutectic and supercritical carbon dioxide in a straight-channel printed circuit heat exchanger

The Printed Circuit Heat Exchanger (PCHE) is considered a promising heat exchanger for Lead-Bismuth Eutectic (LBE) cooled fast reactors due to its superior pressure-bearing capacity and heat transfer efficiency. This paper introduces a conjugate heat transfer solver to investigate the thermo-hydraulic performance of a straight channel PCHE incorporating LBE and Supercritical CO2 (S-CO2). A four-equation model is implemented in the solver to capture the low Prandtl number turbulent heat transfer characteristics of LBE. Comparisons with LBE circular tube experimental results demonstrate that the solver presented enhances the resolution of LBE heat transfer simulations. This improvement in numerical resolution is crucial for understanding and predicting the behaviors of LBE-S-CO2 conjugate heat transfer process. Building on this, the present work explores the impacts of inlet mass flow rate, inlet temperature, S-CO2 pressure, and geometric parameters on the thermo-hydraulic performance of the straight channel PCHE. In terms of inlet temperature, quantitative analyses emphasize the effectiveness of augmenting the mass flow rate on the S-CO2 side to enhance overall heat transfer performance of PCHE. Adjusting the inlet temperature of S-CO2 or LBE to increase the temperature difference between the two fluids improves the average heat transfer rate, but reducing the S-CO2 inlet temperature may decrease the overall heat transfer coefficient. Furthermore, increasing S-CO2 pressure positively affects the thermal conductivity and specific heat capacity of S-CO2, thereby improving the thermo-hydraulic performance of PCHE. Additionally, geometric parameter sensitivity analyses indicate that decreasing wall thickness or increasing ridge width improves heat transfer, but increasing ridge width may significantly increase PCHE’s volume. The increased channel length results in a higher pressure drop, simultaneously enhancing heat transfer. From the Performance Evaluation Criteria (PEC) perspective, lengthening the channel is advantageous for the S-CO2 side but unfavorable for the LBE side. Regarding channel width, reducing channel width yields a larger increase in PEC on the S-CO2 side compared to the LBE side. Therefore, narrower flow channels on the S-CO2 side seem more advantageous. The present work provides a numerical tool with higher numerical resolution for studying LBE-S-CO2 conjugate heat transfer process and offers valuable insights for straight channel PCHE design.

Deformation law and bonding mechanism of 45 carbon steel/316L stainless steel cladding tubes fabricated by three-roll skew rolling bonding process

Realizing the continuous forming and metallurgical bonding in bimetallic cladding tubes with high-strength and corrosion-resistance is the key bottleneck to be solved urgently. In this study, 45 carbon steel/316L stainless steel (CS/SS) cladding tubes were fabricated by the three-roll skew rolling bonding process under different radial reduction rates. The deformation law, interfacial microstructure characteristics, and deformation mechanism were analyzed. With the increase of the radial reduction rates from 11.7 % to 19.3 %, the 45 CS/316L SS cladding tubes were elongated along with the diameter and wall thickness decrease. Besides, the wall thickness ratio between 45 CS and 316L SS was unchanged due to the coordinated deformation. Tensile shear fracture locations of CS/SS cladding tubes were on the 45 CS matrix, and the average diffusion distances in the longitudinal section and the cross section were consistent, proving that uniform metallurgical bonding was achieved. Besides, average decarburized layer thickness decreased and average diffusion distances increased with the increase of radial reduction rates. Furthermore, spherical and fibrous Mn-Si-Cr-O oxides, generated in the insulation heating process, were dispersed near the bonding interface. The refined grains were formed close to the interface, and deformation twins were formed away from the interface on the 316L SS side, whereas only elongated ferrite grains evolved due to the decarburization adjacent to the interface on the 45 CS side. Therefore, the interfacial bonding mechanism was illustrated as three stages, namely the insulation heating stage, the skew rolling bonding stage, and the air cooling stage. The three-roll skew rolling bonding process provides a high-efficiency method to prepare CS/SS cladding tubes with uniform metallurgical bonding, which adopts axial forming and contributes to breaking through the product length size limit.