Response of nitrifiers to gradually increasing pH conditions in a membrane nitrification bioreactor: Microbial dynamics and alkali-resistant mechanism.

Nitrification and nitrifiers are pH-sensitive especially under the alkaline environment in the activated sludge system. However, it is unclear how nitrifiers and nitrification respond to long-term alkaline environment. This study employed a continuous flow membrane nitrification bioreactor to investigate the dynamics of nitrification efficiency and microbial community adaptation under a 320-day alkaline operation.

Segmentation of Heart Sound Signal Based on Multi-Scale Feature Fusion and Multi-Classification of Congenital Heart Disease.

Analyzing heart sound signals presents a novel approach for early diagnosis of pediatric congenital heart disease. The existing segmentation algorithms have limitations in accurately distinguishing the first (S1) and second (S2) heart sounds, limiting the diagnostic utility of cardiac cycle data for pediatric pathology assessment. This study proposes a time bidirectional long short-term memory network (TBLSTM) based on multi-scale analysis to segment pediatric heart sound signals according to different cardiac cycles.

Comparative Study of Single Opening&Closing and Continuous Pulsatile Flow Valve Tester.

Purpose: The purpose is to demonstrate the difference in closing volume fraction between the single opening&closing valve tester (SOCVT) and continuous pulsatile flow valve tester (CPFVT).

Methods: A comparative study was conducted in four hemodynamic conditions selected from the ISO 5840 on the four mitral valve states: normal annulus, 40% annulus dilation, 60% annulus dilation, and repaired valve with a clip device in both the SOCVT and CPFVT. The closing volume fractions were compared and errors calculated in the 16 cases.

A spike-based mRNA vaccine that induces durable and broad protection against porcine deltacoronavirus in piglets.

Unlabelled: Coronaviruses (CoVs) are important pathogens for humans and other vertebrates, causing severe respiratory and intestinal infections that have become a threat to public health because of the potential for interspecies transmission between animals and humans. Therefore, the development of safe, effective vaccines remains a top priority for the control of CoV infection. The unique immunological characteristics of vaccines featuring messenger RNA (mRNA) present an advantageous tool for coronavirus vaccine development.

Attached indigenous microalgal-bacterial consortium with greater stress-resistance facilitated recovery of integrated fixed-film system after experiencing short-term stagnation inhibition.

Stability of integrated fixed-film indigenous microalgal-bacterial consortium (IF-IMBC) requires further investigation. This study focused on the influence of short-term stagnation (STS), caused by influent variations or equipment maintenance, on IF-IMBC. Results showed that the IF-IMBC system experienced initial inhibition followed by subsequent recovery during STS treatment.

PEDV-spike-protein-expressing mRNA vaccine protects piglets against PEDV challenge.

Porcine epidemic diarrhea virus (PEDV), a swine enteropathogenic coronavirus, causes severe diarrhea in neonatal piglets, which is associated with a high mortality rate. Thus, developing effective and safe vaccines remains a top priority for controlling PEDV infection. Here, we designed two lipid nanoparticle (LNP)-encapsulated mRNA (mRNA-LNP) vaccines encoding either the full-length PEDV spike (S) protein or a multiepitope chimeric spike (Sm) protein.

A High-Resolution Network with Strip Attention for Retinal Vessel Segmentation.

Accurate segmentation of retinal vessels is an essential prerequisite for the subsequent analysis of fundus images. Recently, a number of methods based on deep learning have been proposed and shown to demonstrate promising segmentation performance, especially U-Net and its variants. However, tiny vessels and low-contrast vessels are hard to detect due to the issues of a loss of spatial details caused by consecutive down-sample operations and inadequate fusion of multi-level features caused by vanilla skip connections.

Classification of Children's Heart Sounds With Noise Reduction Based on Variational Modal Decomposition.

Purpose: Children's heart sounds were denoised to improve the performance of the intelligent diagnosis.

Methods: A combined noise reduction method based on variational modal decomposition (VMD) and wavelet soft threshold algorithm (WST) was proposed, and used to denoise 103 phonocardiogram samples. Features were extracted after denoising and employed for an intelligent diagnosis model to verify the effect of the denoising method.

A Single-opening&closing Valve Tester for Direct Measurement of Closing Volume of the Heart Valve.

Purpose: The objective of this study was to develop a novel single opening&closing pulsatile flow in-vitro valve tester for direct measurement of closing volume of the heart valve.

Methods: A single opening&closing valve tester was composed of a piston pump, valve mounting chamber, reservoir, measurement and control system. The piston pump was used to drive a valve to open and close with dictated flow which comprised three phases of accelerated, constant, and decelerated flow with six slopes.

Intelligent Diagnosis of Heart Murmurs in Children with Congenital Heart Disease.

Heart auscultation is a convenient tool for early diagnosis of heart diseases and is being developed to be an intelligent tool used in online medicine. Currently, there are few studies on intelligent diagnosis of pediatric murmurs due to congenital heart disease (CHD). The purpose of the study was to develop a method of intelligent diagnosis of pediatric CHD murmurs.

Mechanical Properties and Composition of the Basal Leaflet-Annulus Region of the Tricuspid Valve.

The Tricuspid valve (TV) annulus is a transition structure from the leaflets to the myocardium, with 3 different annulus segments corresponding to the TV leaflets, which includes both basal leaflets and bordering myocardium. The objective of this study was to understand TV annulus mechanical properties and correlate it to the biological composition. The uniaxial testing of the annulus segments from ten porcine TVs was performed to measure Young's modulus (E) and extensibility (ε).

[Research on Control of the Cardiovascular System Based on a Left Ventricular Assist Device].

We propose a control model of the cardiovascular system coupled with a rotary blood pump in the present paper.A new mathematical model of the rotary heart pump is presented considering the hydraulic characteristics and the similarity principle of pumps.A seven-order nonlinear spatial state equation adopting lumped parameter is used to describe the combined cardiovascular-pump model.

Transapical Coaptation Plate for Functional Mitral Regurgitation: An In Vitro Study.

A novel transapical coaptation plate (TCP) device was developed and anchored by sutures in the mitral valve to treat functional mitral regurgitation. The objective of this study was to test efficacy of the TCP in an in vitro model. Eight fresh porcine mitral valves were mounted in a left heart simulator to simulate functional mitral regurgitation by means of annular dilatation and asymmetrical or symmetrical papillary muscle (PM) displacement.

[Numerical Analysis of Two-stage Axial Blood Pump Based on Blood Damage].

The implantable miniaturized axial blood pump works at a high rotational speed,which increases the risk of blood damage.In this article,we aimed to reduce the possibility of hemolysis and thrombosis by designing a twostage axial blood pump.Under the operation conditions of flow rate 5L/min and outlet pressure of 100 mm Hg,we carried out the numerical simulation on the two-stage and single-stage blood pumps to compare the hemolysis and platelet activation state.

Annulus Tension on the Tricuspid Valve: An In-Vitro Study.

Annulus tension (AT) is defined as leaflet tension per unit length of the annulus circumference. AT was investigated to understand tricuspid valve (TV) annulus mechanics. Ten porcine TVs were mounted on a right ventricle rig with an annulus plate to simulate TV closure.

Characterization of biomechanical properties of aged human and ovine mitral valve chordae tendineae.

The mitral valve (MV) is a highly complex cardiac valve consisting of an annulus, anterior and posterior leaflets, chordae tendineae (chords) and two papillary muscles. The chordae tendineae mechanics play a pivotal role in proper MV function: the chords help maintain proper leaflet coaptation and rupture of the chordae tendineae due to disease or aging can lead to mitral valve insufficiency. Therefore, the aim of this study was to characterize the mechanical properties of aged human and ovine mitral chordae tendineae.

Mechanics of mitral valve edge-to-edge-repair and MitraClip procedure.

The edge-to-edge repair (ETER) technique has been used as a stand-alone procedure, or as a secondary procedure with ring annuloplasty for degenerative, functional mitral regurgitation, or for mitral regurgitation of other kinds of valvular etiologies. The percutaneous MitraClip technique based on ETER has been used in patients who are inoperable or at high surgical risk. However, adverse events such as residual mitral regurgitation, and clip detachment or fracture indicate that the mechanics underlying these procedures is not well understood.

A novel coaptation plate device for functional mitral regurgitation: an in vitro study.

A novel mitral valve repair device, coaptation plate (CP), was proposed to treat functional mitral regurgitation. The objective of this study was to test efficacy of the CP in an in vitro model of functional mitral regurgitation. Ten fresh porcine mitral valves were mounted in a left heart simulator, Mitral regurgitation was emulated by means of annular dilatation, and the asymmetrical or symmetrical papillary muscles (PM) displacement.

Tension to passively cinch the mitral annulus through coronary sinus access: an ex vivo study in ovine model.

Introduction: The transcatheter mitral valve repair (TMVR) technique utilizes a stent to cinch a segment of the mitral annulus (MA) and reduces mitral regurgitation. The cinching mechanism results in reduction of the septal-lateral distance. However, the mechanism has not been characterized completely.

Effects of suture position on left ventricular fluid mechanics under mitral valve edge-to-edge repair.

Mitral valve (MV) edge-to-edge repair (ETER) is a surgical procedure for the correction of mitral valve regurgitation by suturing the free edge of the leaflets. The leaflets are often sutured at three different positions: central, lateral and commissural portions. To study the effects of position of suture on left ventricular (LV) fluid mechanics under mitral valve ETER, a parametric model of MV-LV system during diastole was developed.

Annulus tension of the prolapsed mitral valve corrected by edge-to-edge repair.

Background: Mitral valve (MV) performance after edge-to-edge repair (ETER) without ring annuloplasty is suboptimal. ETER efficacy needs to be evaluated from annulus tension (AT) of a prolapsed MV corrected by ETER to understand annular dilatation.

Methods: Ten porcine MVs were harvested and mounted on a MV closure test rig.

An elongation model of left ventricle deformation in diastole.

A numerical method of the left ventricle (LV) deformation, an elongation model, was put forth for the study of LV fluid mechanics in diastole. The LV elongated only along the apical axis, and the motion was controlled by the intraventricular flow rate. Two other LV models, a fixed control volume model and a dilation model, were also used for model comparison and the study of LV fluid mechanics.

Left Ventricular Vortex Under Mitral Valve Edge-to-Edge Repair.

Mitral valve (MV) edge-to-edge repair (ETER) changes MV geometry by approximation of MV leaflets, and impacts left ventricle (LV) filling fluid mechanics. The purpose of this study was to investigate LV vortex with MV ETER during diastole. A computational MV-LV model was developed with MV ETER at the central free edges of the anterior and posterior leaflets.

Mitral valve annulus tension and the mechanism of annular dilation: an in-vitro study.

Background And Aim Of The Study: The mitral annulus mechanics associated with annular dilation in pathologies such as mitral valve (MV) prolapse, ischemic and dilative heart diseases remain unknown. The study aim was to investigate annulus tension (AT) in the dilated annulus and in the displaced papillary muscles due to these pathological conditions.

Methods: Ten porcine MVs were harvested and mounted on a MV closure test rig with the papillary muscles held in the slack, normal, and taut positions.

Mechanics of the mitral valve strut chordae insertion region.

Interest in developing durable mitral valve repair methods is growing, underscoring the need to better understand the native mitral valve mechanics. In this study, the authors investigate the dynamic deformation of the mitral valve strut chordae-to-anterior leaflet transition zone using a novel stretch mapping method and report the complex mechanics of this region for the first time. Eight structurally normal porcine mitral valves were studied in a pulsatile left heart simulator under physiological hemodynamic conditions -120 mm peak transvalvular pressure, 5 l/min cardiac output at 70 bpm.