Temporary Support Research Articles

Quantitative Research on Roof Deformation and Temporary Support Stiffness in Deep-Mine Gob-Side Entry Retaining by Roof Cutting

The important technical process to ensure the success of gob-side entry retaining by roof cutting (GERRC) was the advanced pre-splitting blasting to cut off the mechanical connection between the roadway and working face roof. The whole-cycle roof structure evolution and stress characteristics of GERRC were analyzed. The factors affecting the roof deformation of GERRC were analyzed, and the quantitative relationship between the roof deformation of GERRC and the support stiffness was determined. The results showed that the temporary support stiffness was higher, the support position to the side of the roof cutting was closer, and the roof subsidence deformation of GERRC was smaller. It is proposed to use a single support mass with a high stiffness to control the deformation of the roof, but it also made the support mass and roof elastic potential energy aggregate. To fully utilize the matching of the support stiffness and roof subsidence, improve the stability, and control the subsidence deformation of the roof in GERRC, double-row stacking supports were adopted in the inclination of GERRC, which were used to increase the stiffness of the support system.

Long‐term implications of a multidisciplinary tube‐weaning program: Parental perspectives

AbstractObjectivesChildren who are unable to eat and drink orally require temporary or permanent enteral nutritional support via tube feeding. The objective was to describe a weaning program held at a children's rehabilitation hospital and to review the long‐term outcomes of the transition from tube nutrition to oral feeding.MethodsThe parents of 82 children who took part in the ALYN intervention program from 2011 to 2022 were requested to participate in a telephone survey to learn about their child's status related to eating, education, social wellbeing, and overall health. They also provided feedback concerning their experience with the tube‐weaning program and their current reliance on support for eating‐related issues.ResultsThe parents of 35 (39%) children responded. Their mean ± SD age at the time of treatment were 2.1 ± 1.76, and the mean ± SD age at the time of the survey 8.85 ± 3.96 years. Their mean current zBMI is −0.7. Overall, parents were very satisfied with the child's eating (4.7 out of 5) ± 0.7, and few reported that the child's eating affected the family mealtime routine (2.1 out of 5) ± 1.3. The children's age at weaning was significantly correlated with parental reports of concern with the child's current eating ability, with younger ages at weaning associated with lower parental concern.ConclusionsThe data demonstrated that despite the complexity of the participants, most children succeed in achieving long‐term independent eating, good nutritional status, and social participation around mealtimes.

Chemical Synthesis of Human Proteoforms and Application in Biomedicine.

Limited understanding of human proteoforms with complex posttranslational modifications and the underlying mechanisms poses a major obstacle to research on human health and disease. This Outlook discusses opportunities and challenges of de novo chemical protein synthesis in human proteoform studies. Our analysis suggests that to develop a comprehensive, robust, and cost-effective methodology for chemical synthesis of various human proteoforms, new chemistries of the following types need to be developed: (1) easy-to-use peptide ligation chemistries allowing more efficient de novo synthesis of protein structural domains, (2) robust temporary structural support strategies for ligation and folding of challenging targets, and (3) efficient transpeptidative protein domain-domain ligation methods for multidomain proteins. Our analysis also indicates that accurate chemical synthesis of human proteoforms can be applied to the following aspects of biomedical research: (1) dissection and reconstitution of the proteoform interaction networks, (2) structural mechanism elucidation and functional analysis of human proteoform complexes, and (3) development and evaluation of drugs targeting human proteoforms. Overall, we suggest that through integrating chemical protein synthesis with in vivo functional analysis, mechanistic biochemistry, and drug development, synthetic chemistry would play a pivotal role in human proteoform research and facilitate the development of precision diagnostics and therapeutics.

Relationships between sex and in-hospital outcomes of patients with acute cardiogenic shock receiving mechanical circulatory support

BackgroundCardiovascular disease is the leading cause of mortality in women. Despite this there is a paucity of data on the impact of sex on utilization and outcomes of temporary mechanical circulatory support (tMCS) in patients hospitalized with Acute Myocardial Infarction (AMI) Cardiogenic Shock (CS). MethodsWe examined the 2016–2019 National Inpatient Sample database to identify cases of AMI-CS. Men were used as our control group, while women comprised our cohort. The primary outcome was in-hospital mortality. Secondary outcomes included the use of tMCS including; left ventricular assist device (LVAD) use, Impella use, and Intra-Aortic Balloon Pump (IABP) use, length of stay (LOS) and total hospitalization cost (THC). Multivariate linear and logistic regression models were used to adjust for confounders. ResultsAmong patients hospitalized for AMI (N = 2,622,939), 37.7 % were Female. A Female sex was associated with a higher inpatient mortality (adjusted OR [aOR] 1.06, p < 0.001), a lower likelihood of LVAD use (2.3 % vs. 2.9 % and p < 0.001), IABP use (3.0 % vs. 4.4 % and p < 0.001), Impella use (1.0 % vs. 1.5 % and p < 0.001), a longer mean LOS (4.4 vs 4.3 days and p < 0.001) and lower THC ($88,097 vs. $104,101, p < 0.001) compared to male patients for AMI-CS. ConclusionFemale patients admitted for AMI-CS were less likely to receive tMCS despite a higher mortality rate and a slightly longer LOS compared to male patients. Further studies are necessary to confirm these findings and elucidate clearer causality for such disparities.

Building a Science of Teaching Reading and Vocabulary: Experimental Effects of Structured Supplements for a Read Aloud Lesson on Third Graders’ Domain-Specific Reading Comprehension

ABSTRACT Purpose This study contributes to the science of teaching reading and vocabulary by illustrating how a ubiquitous classroom practice – read alouds – can be enhanced by structured supplements. This experimental study examines whether and to what extent providing structured supplements can improve student comprehension outcomes by helping teachers foster discussions about academic vocabulary that support schema transfer as students make connections between known and new topics. Method A total of 80 third-grade teachers and their students (N = 965; 32% Black, 31% Hispanic, 25% white, 9 Asian, 48% Male) were randomly assigned to treatment or control conditions. Treatment students received a single social studies read aloud on the story of Apollo 11 with structured supplements while control students received the same read aloud story but without structured supplements. Students were from linguistically, economically, and ethnically diverse backgrounds. Results Effect sizes from hierarchical linear models indicated that students in the treatment condition outperformed students in the control condition on four measures of domain-specific reading comprehension: recall (ES = .17), near-transfer (ES = .17), mid-transfer (ES = .18), and content comprehension (ES = .18). Further exploratory analyses using structural equation modeling revealed that teacher language scaffolds – that is, temporary dialogic supports in which teachers went above and beyond the intervention script – explained 66% of the treatment effect on domain-specific reading comprehension. Conclusion Results from this study suggest that read alouds, when enhanced with structured supplements designed to facilitate schema transfer, can increase the amount of academic vocabulary teachers use during classroom instruction and improve their students’ ability to comprehend disciplinary texts.

Corrosion Resistance of Biodegradable Zinc Surfaces Enhanced by UV-Grafted Polydimethylsiloxane Coating.

Improved living conditions have led to an increase in life expectancy worldwide. However, as people age, the risk of vascular disease tends to increase due to the accumulation and buildup of plaque in arteries. Vascular stents are used to keep blood vessels open. Biodegradable stents are designed to provide a temporary support vessel that gradually degrades and is absorbed by the body, leaving behind healed blood vessels. However, biodegradable metals can suffer from reduced mechanical strength and/or inflammatory response, both of which can affect the rate of corrosion. Therefore, it is essential to achieve a controlled and predictable degradation rate. Here, we demonstrate that the corrosion resistance of biodegradable Zn surfaces is improved by electroless deposition of zinc hydroxystannate followed by UV-grafting with silicone oil (PDMS). Potentiodynamic polarization, electrochemical impedance spectroscopy, respiratory kinetic measurements, and long-term immersion in three simulated body fluids were applied. Although zinc hydroxystannate improves the corrosion resistance of Zn to some extent, it introduces a high surface area with hydroxyl units used to UV-graft PDMS molecules. Our results demonstrate that hydrophobic PDMS causes a 3-fold reduction in corrosion of Zn-based materials in biological environments and reduces cytotoxicity through the uncontrolled release of Zn ions.

Bridge to Life: Current Landscape of Temporary Mechanical Circulatory Support in Heart-Failure-Related Cardiogenic Shock.

Acute heart failure (HF) presents a significant mortality burden, necessitating continuous therapeutic advancements. Temporary mechanical circulatory support (MCS) is crucial in managing cardiogenic shock (CS) secondary to acute HF, serving as a bridge to recovery or durable support. Currently, MCS options include the Intra-Aortic Balloon Pump (IABP), TandemHeart (TH), Impella, and Veno-Arterial Extracorporeal Membrane Oxygenation (VA-ECMO), each offering unique benefits and risks tailored to patient-specific factors and clinical scenarios. This review examines the clinical implications of recent advancements in temporary MCS, identifies knowledge gaps, and explores promising avenues for future research and clinical application. Understanding each device's unique attributes is crucial for their efficient implementation in various clinical scenarios, ultimately advancing towards intelligent, personalized support strategies.

Treatment time limit for successful weaning from veno-arterial extracorporeal membrane oxygenation in cardiogenic shock.

Knowing the upper time limit for successful weaning from temporary mechanical circulatory support in cardiogenic shock will help with decision-making regarding advanced heart failure (HF) therapy or considering withdrawal of care. The aim of this study was to investigate the association between the support duration and successful weaning from veno-arterial extracorporeal membrane oxygenation (VA-ECMO) in patients with cardiogenic shock. A retrospective single-centre cohort study was conducted between January 2013 and June 2023. It included 100 consecutive patients with cardiogenic shock who were treated with VA-ECMO. Patients with out-of-hospital cardiac arrest were excluded. The primary outcome was successful weaning from VA-ECMO (i.e., VA-ECMO decannulation and survival to discharge). The association between the length of support duration and the weaning success rate was analysed. Patients were divided into three groups according to ECMO support duration: Group A (≤7days), Group B (8-14days), and Group C (≥15days). Multivariable logistic regression analysis was used to evaluate the impact of the length of support duration on successful weaning of VA-ECMO. The median age was 67years, and 73% of study participants were male. The underlying aetiologies of cardiogenic shock were as follows: acute myocardial infarction, 50; fulminant myocarditis, 19; cardiomyopathy, 15; valvular heart disease, 8; and other, 8. Seventy-five patients (75%) were attempted to wean VA-ECMO, and 67 moved on to decannulation. In total, 43 (43%) patients were successfully weaned from VA-ECMO. The median length of ECMO support duration was 8 [3-15] days. Compared with those who underwent successful ECMO decannulation, those who did not had a significantly longer support duration of VA-ECMO (5 [3-9] days vs. 12 [3-22] days, P=0.004). The weaning success rate was significantly higher in patients with short support duration; 58% (29/50), 40% (10/25), 16% (4/25) in Groups A, B, and C, respectively (P=0.002). Overall, none of the patients supported for over 24days (0/11) were successfully weaned from VA-ECMO. On multivariable logistic regression analysis, the length of support duration was independently associated with successful weaning after adjusting for age, sex, underlying aetiology, and left ventricular ejection fraction (odds ratio, 0.813 [per 3days]; 95% confidence interval, 0.679-0.914; P=0.025). Long support duration of VA-ECMO was significantly associated with a low rate of successful weaning in patients with cardiogenic shock. Patients who require VA-ECMO for over 1week should start considering advanced HF therapy or withdrawal of care.

Three-Year Left Ventricular Assist Device Outcomes and Strategy After Heart Transplant Allocation Score Change

BackgroundThe United Network for Organ Sharing (UNOS) adopted new criteria for the heart allocation score on 10/18/2018 to reflect changing trends of candidates’ mortality while awaiting transplant. We examined the impact of these policy changes on rates of left ventricular assist device (LVAD) implantation and outcomes posttransplant from a relatively newer UNOS database. MethodsThe UNOS registry was used to identify first-time adult heart recipients with LVAD at listing or transplant who underwent transplantation between 1/1/2016 and 3/10/2020. Survival data was collected through 3/30/2023. Those listed prior to 10/18/2018 but transplanted after were excluded. Patients were divided into before or after change groups. Demographics and clinical parameters were compared. Survival was analyzed with Kaplan-Meier curves and log-rank tests. A p<0.05 was considered significant. ResultsWe identified 4387 heart recipients with LVAD in the before (n=3606) and after (n=781) score change eras. The after group had a lower rate of LVAD implantation while listed compared to the before group (20.4% vs 34.9%, p<0.0001), and were more likely to be female (25.1% vs 20.2%, p=0.002); in both groups, most recipients (62.8%) were white. There was significantly farther distance from the donor hospital to transplant center in the after group (264.4 NM vs 144.2NM, p<0.0001) and decreased waitlist days (84.9 ± 105.1 vs 369.2 ± 459.5, p<0.0001). Recipients in the after group were more likely to utilize ECMO (3.7% vs 0.5%, p<0.0001) and IV inotropes (19.1% vs 7.5%, p<0.0001), and receive a CDC increased-risk donor organ (37.9% vs 30.5%, p<0.0001). Survival at 3-years was comparable between the two groups. ConclusionsThe allocation score change in 2018 yielded considerable changes in mechanical circulatory support device implantation strategy and outcomes. The rate of LVAD implantation decreased with increased utilization of temporary mechanical circulatory support devices.

A multidisciplinary program to wean infants and toddlers from long-term tube feeding: Lessons learned from a retrospective study.

Children maintain growth and development by ingesting adequate calories and nutrients, typically achieved via oral intake of food and liquids. When unable to eat and drink orally, they need temporary or permanent enteral nutritional support via nasogastric, nasoduodenal, gastrostomy, or jejunostomy tubes. The objectives of this retrospective study are to describe lessons learned from operating a weaning program at ALYN Hospital for over a decade, the characteristics of the patient population (gender, age, medical condition, and type of tube feeding and hospitalization), and which of these characteristics correlate with successful weaning. Data were obtained from the hospital's secure database of 82 infants and toddlers, 37 boys (45.4%) and 45 girls (54.9%) aged 3 months to 10.8 years who took part in a tube feeding intervention from 2011 to 2020. Descriptive and correlational analyses were performed to characterize the participants and their responses to the program. Fifty-one children (62.2%) were less than 2 years, 26 children (31.7%) were 2-4.11 years, and only 5 children were aged 5 years (6.1%) and older. Fifty-six children were successfully weaned from tube feeding, 9 children were eventually successful, but the process took longer than anticipated, 11 children were partially weaned and 6 were not successfully weaned. These results are discussed within the context of a successful weaning program related to participant characteristics (medical condition, age, gender, and weight), and subsequent recommendations are offered related to the intervention setting, duration, and intensity; redefining success in weaning and the need for long-term follow-up.

Prolonged Impella 5.0/5.5 support within different pathways of care for cardiogenic shock: the experience of a referral center.

Impella 5.0 and 5.5 are promising low-invasive left ventricle (LV) temporary mechanical circulatory supports (tMCS) for cardiogenic shock due to LV mechanical unloading and are paired with powerful hemodynamic support. This study aimed to analyze data and destinies of patients supported with Impella 5.0/5.5 at a national referral center for cardiogenic shock and to assess the parameters associated with myocardial recovery and successful weaning. A single-center observational study was conducted on all patients treated with Impella 5.0 or 5.5 from March 2018 to July 2023. A total of 59 patients underwent Impella 5.0/5.5 implantation due to profound cardiogenic shock, with acute myocardial infarction being the most frequent cause of shock (42 patients, 71%). The median duration of Impella support was 13 days (maximum duration of 52 days). Axillary cannulation was feasible in almost all patients, and 36% were mobilized during support. A total of 44 patients (75%) survived to the next therapy/recovery: 21 patients experienced recovery and 15 and 8 were bridged to long-term LVAD and heart transplantation, respectively. The global survival rate was 66%. The predictors of native heart recovery at multivariate analysis were the number of days on tMCS before upgrade to Impella 5.0/5.5 [hazard ratio (HR) 0.68 (0.51-9) p = 0.0068] and improvement of LVEF within the first 7-10 days of support [HR 4.72 (1.34-16.7), p = 0.016]. Transcatheter systems such as Impella 5.0/5.5 revolutionized the field of tMCS. Myocardial recovery is the primary clinical target. Its prognostication and promotion are key to ensure the most proficuous course for each patient from cardiogenic shock to long-term event-free survival.

Current practices in the management of temporary mechanical circulatory support: A survey of CICU directors in North America

Despite the growing use of temporary mechanical circulatory support (tMCS), little data exists to inform management and weaning of these devices. We performed an online survey among cardiac intensive care unit directors in North America to examine current practices in the management of patients treated with intraaortic balloon pump and Impella. We received responses from 84% of surveyed centers (n=37). Our survey focused on three key aspects of daily management: 1. Hemodynamic monitoring; 2. Hemocompatibility; and 3. Weaning and removal. We found substantial variability surrounding all three areas of care. Our findings highlight the need for consensus around practices associated with improved outcomes in patients treated with tMCS.

Pragmatic approach to temporary mechanical circulatory support in acute right ventricular failure

Acute right ventricular failure (RVF) is prevalent in multiple disease states and is associated with poor clinical outcomes. Right-sided temporary mechanical circulatory support (tMCS) devices are used to unload RV congestion and increase cardiac output in cardiogenic shock (CS) with hemodynamically significant RVF. Several RV-tMCS device platforms are available; however consensus is lacking on patient selection, timing of escalation to RV-tMCS, device management, and device weaning. The purposes of this review are to 1) describe the current state of tMCS device therapies for acute RVF with CS, 2) discuss principles of escalation to RV-tMCS device therapy, 3) examine important aspects of clinical management for patients supported by RV-tMCS devices including volume management, anticoagulation, and positive pressure ventilation, and 4) provide a framework for RV-tMCS weaning.

Durable left ventricular assist devices following temporary circulatory support on a microaxial flow pump with and without extracorporeal life support

BackgroundCirculatory support with a catheter-based microaxial flow pump (mAFP) plays a major role in the treatment of severe cardiogenic shock. In most patients who fail to recover while on temporary mechanical circulatory support (tMCS) and who are not eligible for heart transplantation, durable left ventricular assist device (dLVAD) implantation is usually considered a reliable option. This study aimed to describe the outcome of dLVAD therapy following mAFP support and to identify predictors of mortality. MethodsThis was a retrospective analysis of data from a multicenter registry on patients who underwent dLVAD implantation following tMCS with a mAFP between January 2017 and October 2022 (n = 332) from 19 European centers. ResultsPatients were supported with an Impella 5.5 (n = 92), 5.0 (n = 153) or CP (n = 87) and were transitioned to a HeartWare HVAD (n = 128) or Heartmate 3 (n = 204) during the same period. One hundred and twenty-five patients (39.2%) also required extracorporeal life support before and/or during mAFP therapy. The 30-day and 1-year survival were 87.8% and 71.1%, respectively. The following risk factors for 1-year mortality were identified: age (odds ratio [OR], 1.02), specifically age over 55 years (OR, 1.09), body mass index >30 kg/m2 (OR, 2.2), female sex (OR for male sex, 0.43), elevated total bilirubin (OR, 1.12), and low platelet count (OR, 0.996). ConclusionsBased on the identified risk factors, a risk score for estimating 1-year mortality was calculated to optimize patient selection for dLVAD implantation.

Mixed Shock Complicating Cardiogenic Shock: Frequency, Predictors, and Clinical Outcomes.

Patients presenting with cardiogenic shock (CS) are at risk of developing mixed shock (MS), characterized by distributive-inflammatory phenotype. However, no objective definition exists for this clinical entity. We assessed the frequency, predictors, and prognostic relevance of MS complicating CS, based on a newly proposed objective definition. MS complicating CS was defined as an objective shock state secondary to both an ongoing cardiogenic cause and a distributive-inflammatory phenotype arising at least 12 hours after the initial CS diagnosis, as substantiated by predefined longitudinal changes in hemodynamics, clinical, and laboratory parameters. Among 213 consecutive patients admitted at 2 cardiac intensive care units with CS, 13 with inflammatory-distributive features at initial presentation were excluded, leading to a cohort of 200 patients hospitalized with pure CS (67±13 years, 96% Society of Cardiovascular Angiography and Interventions CS stage class C or higher). MS complicating CS occurred in 24.5% after 120 (29-216) hours from CS diagnosis. Lower systolic arterial pressure (P=0.043), hepatic injury (P=0.049), and suspected/definite infection (P=0.013) at CS diagnosis were independent predictors of MS development. In-hospital mortality (53.1% versus 27.8%; P=0.002) and hospital stay (21 [13-48] versus 17 [9-27] days; P=0.018) were higher in the MS cohort. At logistic multivariable analysis, MS diagnosis (odds ratio [OR], 3.00 [95% CI, 1.39-6.63]; Padj=0.006), age (OR, 1.06 [95% CI, 1.03-1.10] years; Padj<0.001), admission systolic arterial pressure <100 mm Hg (OR, 2.41 [95% CI, 1.19-4.98]; Padj=0.016), and admission serum creatinine (OR, 1.61 [95% CI, 1.19-2.26]; Padj=0.003) conferred higher odds of in-hospital death, while early temporary mechanical circulatory support was associated with lower in-hospital death (OR, 0.36 [95% CI, 0.17-0.75]; Padj=0.008). MS complicating CS, objectively defined leveraging on longitudinal changes in distributive and inflammatory features, occurs in one-fourth of patients with CS, is predicted by markers of CS severity and inflammation at CS diagnosis, and portends higher hospital mortality.

Plastic-sleeve test method to measure autogenous and drying shrinkage in paste, mortar, and concrete: Test Results

The Plastic-Sleeve Test (PST) method of molding cylindrical specimens in plastic sleeves enables the measurement of autogenous and total shrinkage of pastes, mortars, and concretes. Photogrammetric tests confirmed that the linear support of the specimens with a temporary bottom support mold does not restrain deformation. Tests were performed to compare the PST versus corrugated tube methods and similar relative humidity and autogenous shrinkage results were obtained. The PST shows comparable CoV values to those of the corrugated tube test. The method presented provides solid circular cross-section samples, enabling control over entrapped air content, specimen shape, and bleeding effects, thereby ensuring the measurement method’s high repeatability. The PST showed a tighter seal than prismatic samples molded for total shrinkage testing according to EN 1367-4. Results indicate that the PST can effectively be used for molding samples intended for total shrinkage measurement. It is concluded that the PST method is an effective method to measure autogenous shrinkage and total shrinkage of cementitious materials.

Three-Dimensional and Two-Dimensional Stability Analysis of Bentonite Slurry Trenches Using a Shear Strength Reduction Technique and Limit Equilibrium Methods

Bentonite slurry trenches are becoming increasingly popular in the excavation of trenches, especially for diaphragm wall construction. The problem that needs to be addressed is the stability of bentonite slurry trenches. This paper presents a stability analysis of trenches with temporary support from bentonite slurry, with unit weights ranging from 10.5 to 12.0 kN/m3 in the realistic stratum, and C3 in the Hue city area. Our analysis employs the Shear Strength Reduction Technique (SSR) with Mohr–Coulomb materials to numerically evaluate the factor of safety (FS). The finite element method (FEM) software program (RS2 v. 121 and RS3 v. 4.0) and the finite difference method (FDM) FLAC v. 7.0 software were used. Additionally, the limit equilibrium method (LEM) of Bell–Washbourne and three-dimensional (3D) Bishop were used to calculate trench stability. The results of the analysis show a good agreement between RS2 and FLAC2D, and between RS3 and FLAC3D. Secondly, upon comparison, it was noted that the factor of safety of the 3D software programs (RS3 v. 4.0, FLAC v. 7.0) was higher than that of the 2D software programs (RS2 v. 11.0, FLAC v. 7.0), ranging from 52.3 to 63.0% for trench lengths of 6 m. However, for trench lengths of 54 m, the factor of safety values in 2D and 3D configurations were nearly equal. Thirdly, the factor of safety of the Bell–Washbourne method (LEM) was lower than that of the numerical analysis methods (FLAC and RS programs). Using the three-dimensional numerical method appears to be effective for estimating stability.

Numerical investigation of artificial ground freezing–thawing processes in tunnel construction

Artificial ground freezing is a frequently used method for temporary support of the soil in geotechnical interventions, such as tunneling. Besides the time required to form a supporting frozen soil structure during freezing, the prediction of temperature evolution during the thawing process and the final thawing time are also relevant, since settlements induced by thawing of the frozen soil can pose a risk to sensitive structures in urban tunneling. The freezing and thawing process of soils depends strongly on the unfrozen liquid content. The unfrozen liquid content during the freezing and thawing cycles is known to have a pronounced hysteresis response, whose effect on the temperature distribution and groundwater flow, especially at the structural level has not been extensively studied. In this work, we present a thermo-hydraulic finite element model for freezing soils and incorporate the hysteresis behavior of soil. We aim to investigate the suitability of the presented numerical model for tunnel construction on the one hand, and quantify the extent of the influence of the hysteresis response of the unfrozen liquid content at the structural level on the other. To this end, the model is first validated with the help of experimental data from a soil test subjected to a freezing–thawing cycle and subsequently used to analyze three problems of artificial ground freezing in tunnel construction during the freezing phase or freezing–thawing phases. The results show a good agreement with the experimental measurements. We show that the computational model is capable of providing accurate prognosis of the temperature profile as well as broader metrics such as the thickness and shape of the frozen body for tunneling applications under hydrostatic and seepage flow conditions. The hysteresis response is shown to have a significant influence on the coupled thermo-hydraulic process, with thawing times differing depending on whether hysteresis is considered. It is concluded, that the inclusion of the hysteresis response is crucial for obtaining an accurate representation of the freezing process.

Mechanical management of refractory form of heart failure

Although the initial management of heart failure is essentially pharmacological, the use of mechanical circulatory support may become necessary in advanced forms. In cardiogenic shock, temporary mechanical circulatory support should be considered, while in more stable forms of advanced heart failure, implantation of a long-term left ventricular assist device (LVAD) can prolong survival and improve patient's quality of life. Recent improvements in LVAD technology have reduced post-implant complications, but the procedure is not without risk and requires close clinical follow-up.

Support mechanical response analysis and surrounding rock pressure calculation method for a shallow buried super large section tunnel in weak surrounding rock

At present, China's demand for high-speed railway construction is constantly increasing, and the construction of Multi line high-speed railway tunnels has been put on the agenda. The design and construction issues of super-large-sections tunnels urgently need to be addressed. The Xiabei mountain No. 1 and No. 2 tunnels in the Hangzhou-Taizhou Railway are typical shallow-buried super-large-section-tunnels in weak surrounding rock, and their design and construction issues are representative. Eleven monitoring sections were set up in the tunnel, including tunnel deformation, surrounding rock, shotcrete, steel frames, bolts and temporary support mechanical responses. Taking the monitoring data of the most typical cross-section as an example, the mechanical response of the support structure of a shallow-buried super-large-section tunnel was analyzed in detail. Based on previous research results, this paper discusses and summarizes the common construction problems of this type of tunnel, and puts forward corresponding suggestions. The existing formula for calculating surrounding rock pressure has poor applicability to super-large-section tunnels constructed by step excavation, resulting in conservative support parameters. Therefore, based on the monitoring values of surrounding rock pressure at 10 monitoring sections in Xiabei mountain No. 1 and No. 2 tunnels, empirical parameters reflecting the impact of step excavation were summarized. Based on the Wang formula and combined with the step excavation empirical parameters, an empirical formula for the surrounding rock pressure of shallow-buried super-large-section tunnels considering step excavation was constructed. The calculated results are in good agreement with the on-site monitoring data. This study can provide a good reference for similar projects.