Characterization of Flow Dynamics in the Pulmonary Bifurcation of Patients With Repaired Tetralogy of Fallot: A Computational Approach

The hemodynamic environment of the pulmonary bifurcation is of great importance for adult patients with repaired tetralogy of Fallot (rTOF) due to possible complications in the pulmonary valve and narrowing of the left pulmonary artery (LPA). The aim of this study was to computationally investigate the effect of geometrical variability and flow split on blood flow characteristics in the pulmonary trunk of patient-specific models. Data from a cohort of seven patients was used retrospectively and the pulmonary hemodynamics was investigated using averaged and MRI-derived patient-specific boundary conditions on the individualized models, as well as a statistical mean geometry. Geometrical analysis showed that curvature and tortuosity are higher in the LPA branch, compared to the right pulmonary artery (RPA), resulting in complex flow patterns in the LPA. The computational analysis also demonstrated high time-averaged wall shear stress (TAWSS) at the outer wall of the LPA and the wall of the RPA proximal to the junction. Similar TAWSS patterns were observed for averaged boundary conditions, except for a significantly modified flow split assigned at the outlets. Overall, this study enhances our understanding about the flow development in the pulmonary bifurcation of rTOF patients and associates some morphological characteristics with hemodynamic parameters, highlighting the importance of patient-specificity in the models. To confirm these findings, further studies are required with a bigger cohort of patients

Signal trends of microbial fuel cells fed with different food-industry residues

A microbial fuel cell (MFC) is an anaerobic bioreactor where soluble metabolites liberated by hydrolysis and fermentation of macromolecules are simultaneously available for anode respiring bacteria (ARB). ARB can be influenced by chemical imbalances in the liquid phase of the bioreactor. The objective of the work was to explore the trend of electric signals generated by MFCs, in relation to anaerobic biodegradation of four different solid food-industry residual substrates. Four sets of membraneless single-chamber MFCs were operated in batch mode, with solid waste substrates characterized by a different base component: i) mixed kitchen waste (fibers), ii) whey from dairy industries (sugar), iii) fisheries residues previously processed to recover oils (proteins), iv) pulp waste from citrus juice production (acidic). All the tested MFCs were able to produce an electric output with different trends, depending on the principal component of the solid substrate. MFC potential varied as function of the COD and the feeding cycle, as well as of the substrate. The pH variability during the fermentative process significantly affected the electric output. Citrus (acidic) pulp fed MFCs started to operate only when the pH raised up 6.5. MFCs fed with mix kitchen wastes had a relatively stable electric signal; fish based waste caused spiking in the MFC signal and an averaging in the COD degradation trend. This phenomenon was attributed to a pH instability induced by proteins degradation forming ammonia. The fermentation process was strongly predominant with respect the electrochemical process in MFCs and the coulombic efficiency (CE) was low, ranging between 2 and 10%. This result call for a deeper exploration of harvesting power from solid wastes and pointed also to the possibility of using a MFC to monitor important parameters of fermentation processes in biotech production plants

The Science Behind the Springs: Using Biomechanics and Finite Element Modeling to Predict Outcomes in Spring-Assisted Sagittal Synostosis Surgery

Spring-assisted surgery for the correction of scaphocephaly has gained popularity over the past 2 decades. Our unit utilizes standardized torsional springs with a central helix for spring-assisted surgery. This design allows a high degree of accuracy and reproducibility of the force vectors and force distance curves. In this manuscript, we expand on the biomechanical testing and properties of these springs. Standardization of design has enabled us to study the springs on bench and in vivo and a comprehensive repository of calvarial remodeling and spring dynamics has been acquired and analyzed. Finite element modeling is a technique utilized to predict the outcomes of spring-assisted surgery. We have found this to be a useful tool, in planning our surgical strategy and improving outcomes. This technique has also contributed significantly to the process of informed consent preoperatively. In this article, we expand on our spring design and dynamics as well as the finite element modeling used to predict and improve outcomes. In our unit, this practice has led to a significant improvement in patient outcomes and parental satisfaction and we hope to make our techniques available to a wider audience

Bioelectrochemical Nitrogen fixation (e-BNF): Electro-stimulation of enriched biofilm communities drives autotrophic nitrogen and carbon fixation

A new approach to microbial electrosynthesis is proposed, aimed at producing whole biomass from N2 and inorganic carbon, by electrostimulation of complex microbial communities. On a carbon-based conductor under constant polarization ( 120.7\u202fV vs SHE), an electroactive biofilm was enriched with autotrophic nitrogen fixing microorganims and led to biomass synthesis at higher amounts (up to 18 fold), as compared to controls kept at open circuit (OC). After 110\u202fdays, the electron transfer had increased by 30-fold, as compared to abiotic conditions. Metagenomics evidenced Nif genes associated with autotrophs (both Archaea and Bacteria) only in polarized biofilms, but not in OC. With this first proof of concept experiment, we propose to call this promising field \u2018bioelectrochemical nitrogen fixation\u2019 (e-BNF): a possible way to \u2018power\u2019 biological nitrogen fixation, organic carbon storage and soil fertility against desertification, and possibly a new tool to study the development of early prokaryotic life in extreme environments

NMR quantification of 16-O-methylcafestol and kahweol in Coffea canephora var. robusta beans from different geographical origins

Diterpenes have recently received a great deal of interest as tools to investigate the botanical origin of coffee. Specifically, kahweol has been proposed as a marker of Coffea arabica while 16-O-methylcafestol (16-OMC) is a Coffea canephora specific marker and its detection and quantification allow the authenticity of pure C. arabica roasted coffee blends to be assessed. In this study, we evaluated the possibility of the industrial use of the quantification of these diterpenes to assess the relative amounts of the two coffee species in blends. The content of 16-OMC and kahweol was determined in 78 samples (i.e., 39 green and the corresponding 39 roasted beans) of C. canephora from different geographical origins using a recently published NMR approach. Our results show a small natural variability in 16-OMC content for the Asian samples (average content = 1837 \ub1 113 mg/kg) while a much larger spread was found for the African samples (average content = 1744 \ub1 322 mg/kg). This large variability prevents the use of 16-OMC to quantify C. canephora in unknown roasted coffee blends. We also show that kahweol cannot be considered a specific C. arabica marker since it was detected almost all coffees and quantified in about 30% of the C. canephora samples

Patient-specific blood flow simulations in the pulmonary bifurcation of patients with tetralogy of fallot

Dysfunction of the pulmonary valve and narrowing of the branch pulmonary arteries are common chronic complications in adult patients with tetralogy of Fallot; the most common cyanotic congenital heart disease with an estimate prevalence 1 in 3000 live births. Clinical consequences include, but are not limited to, abnormal lung development and elevated pulmonary vascular resistance. It is, therefore, crucial to better understand and characterise the haemodynamic environment in the pulmonary bifurcation to better diagnose and treat these patients. In this study, we have focused on investigating the blood flow dynamics in patient-specific geometries of the pulmonary bifurcation by means of computational models

Current treatment strategies in managing side effects associated with domiciliary positive airway pressure (PAP) therapy for patients with sleep disordered breathing: A systematic review and meta-analysis

Sleep disordered breathing is commonly treated with positive airway pressure therapy. Positive airway pressure therapy is delivered via a tight-fitting mask with common side effects including: leak, ineffective treatment, residual sleep disordered breathing, eye irritation, nasal congestion, pressure ulcers and poor concordance with therapy. This systematic review and meta-analysis aimed to identify the effectiveness of current treatment strategies for managing side effects associated with positive airway pressure therapy. Five databases were searched and 10,809 articles were screened, with 36 articles included in the review. Studies investigated: dressings, nasal spray/douche, chin straps, heated humidification and interfaces. No intervention either improved or detrimentally affected: positive airway pressure concordance, Epworth Sleepiness Score, residual apnoea hypopnea index or interface leak. The review was limited by study heterogeneity, particularly for outcome measures. Additionally, patient demographics were not reported, making it difficult to apply the findings to a broad clinical population. This review highlights the paucity of evidence supporting treatment strategies to manage side effects of positive airway pressure therapy