CFD simulation of anaerobic granular sludge reactors: A review.

Anaerobic digestion processes can generate renewable energy in the form of biogas while treating organic wastewater. The generation of biogas within anaerobic digestion systems is directly linked to the mixing conditions inside the reactors. In high-rate reactors such as the upflow anaerobic sludge blanket (UASB) reactor, the expanded granular sludge bed (EGSB) reactor and the internal circulation (IC) reactor, the hydrodynamic behaviour will depend on the interactions between the wastewater, the biogas, and the biomass granules. Over the past few years, various researchers have used computational fluid dynamics (CFD) to study the hydrodynamic behaviour in these types of reactors. This review aims to present and critically discuss the state of the art in the use of CFD applied to anaerobic granular sludge reactors (AGSRs). It briefly introduces and discusses the various aspects of modelling. It also reviews the various papers which used CFD to model these reactors and critically analyses the models used for the simulations in terms of general approaches and single-phase vs multiphase studies. The methods used in the validation of the CFD models are also described and discussed. Based on the findings, the challenges and future perspectives for the CFD modelling of AGSRs are discussed and gaps in the knowledge are identified.

Premature delivery in the domestic sow in response to in utero delivery of AAV9 to fetal piglets.

Numerous pediatric neurogenetic diseases may be optimally treated by in utero gene therapy (IUGT); but advancing such treatments requires animal models that recapitulate developmental physiology relevant to humans. One disease that could benefit from IUGT is the autosomal recessive motor neuron disease spinal muscular atrophy (SMA). Current SMA gene-targeting therapeutics are more efficacious when delivered shortly after birth, however postnatal treatment is rarely curative in severely affected patients. IUGT may provide benefit for SMA patients. In previous studies, we developed a large animal porcine model of SMA using AAV9 to deliver a short hairpin RNA (shRNA) directed at porcine survival motor neuron gene (Smn) mRNA on postnatal day 5. Here, we aimed to model developmental features of SMA in fetal piglets and to demonstrate the feasibility of prenatal gene therapy by delivering AAV9-shSmn in utero. Saline (sham), AAV9-GFP, or AAV9-shSmn was injected under direct ultrasound guidance between gestational ages 77-110 days. We developed an ultrasound-guided technique to deliver virus under direct visualization to mimic the clinic setting. Saline injection was tolerated and resulted in viable, healthy piglets. Litter rejection occurred within seven days of AAV9 injection for all other rounds. Our real-world experience of in utero viral delivery followed by AAV9-related fetal rejection suggests that the domestic sow may not be a viable model system for preclinical in utero AAV9 gene therapy studies.

Monocyte metabolic transcriptional programs associate with resistance to tuberculin skin test/interferon-γ release assay conversion.

After extensive exposure to Mycobacterium tuberculosis (Mtb), most individuals acquire latent Mtb infection (LTBI) defined by a positive tuberculin skin test (TST) or interferon-γ release assay (IGRA). To identify mechanisms of resistance to Mtb infection, we compared transcriptional profiles from highly exposed contacts who resist TST/IGRA conversion (resisters, RSTRs) and controls with LTBI using RNAseq. Gene sets related to carbon metabolism and free fatty acid (FFA) transcriptional responses enriched across 2 independent cohorts suggesting RSTR and LTBI monocytes have distinct activation states. We compared intracellular Mtb replication in macrophages treated with FFAs and found that palmitic acid (PA), but not oleic acid (OA), enhanced Mtb intracellular growth. This PA activity correlated with its inhibition of proinflammatory cytokines in Mtb-infected cells. Mtb growth restriction in PA-treated macrophages was restored by activation of AMP kinase (AMPK), a central host metabolic regulator known to be inhibited by PA. Finally, we genotyped AMPK variants and found 7 SNPs in PRKAG2, which encodes the AMPK-γ subunit, that strongly associated with RSTR status. Taken together, RSTR and LTBI phenotypes are distinguished by FFA transcriptional programs and by genetic variation in a central metabolic regulator, which suggests immunometabolic pathways regulate TST/IGRA conversion.

Muscle contractility dysfunction precedes loss of motor unit connectivity in SOD1(G93A) mice.

INTRODUCTION: Electrophysiological measurements are used in longitudinal clinical studies to provide insight into the progression of amyotrophic lateral sclerosis (ALS) and the relationship between muscle weakness and motor unit (MU) degeneration. Here, we used a similar longitudinal approach in the Cu/Zn superoxide dismutase (SOD1[G93A]) mouse model of ALS. METHODS: In vivo muscle contractility and MU connectivity assays were assessed longitudinally in SOD1(G93A) and wild type mice from postnatal days 35 to 119. RESULTS: In SOD1(G93A) males, muscle contractility was reduced by day 35 and preceded MU loss. Muscle contractility and motor unit reduction were delayed in SOD1(G93A) females compared with males, but, just as with males, muscle contractility reduction preceded MU loss. DISCUSSION: The longitudinal contractility and connectivity paradigm employed here provides additional insight into the SOD1(G93A) mouse model and suggests that loss of muscle contractility is an early finding that may precede loss of MUs and motor neuron death. Muscle Nerve 59:254-262, 2019.

Reactivation of RNA metabolism underlies somatic restoration after adult reproductive diapause in C. elegans.

The mechanisms underlying biological aging are becoming recognized as therapeutic targets to delay the onset of multiple age-related morbidities. Even greater health benefits can potentially be achieved by halting or reversing age-associated changes. C. elegans restore their tissues and normal longevity upon exit from prolonged adult reproductive diapause, but the mechanisms underlying this phenomenon remain unknown. Here, we focused on the mechanisms controlling recovery from adult diapause. Here, we show that functional improvement of post-mitotic somatic tissues does not require germline signaling, germline stem cells, or replication of nuclear or mitochondrial DNA. Instead a large expansion of the somatic RNA pool is necessary for restoration of youthful function and longevity. Treating animals with the drug 5-fluoro-2'-deoxyuridine prevents this restoration by blocking reactivation of RNA metabolism. These observations define a critical early step during exit from adult reproductive diapause that is required for somatic rejuvenation of an adult metazoan animal.

Totally Endovascular Management of Popliteal Artery Occlusion and Pseudoaneurysm Formation after Total Knee Replacement.

Injuries to the popliteal artery during total knee arthroplasty (TKA) are rare. We present a case of a 72-year-old man with popliteal artery thrombosis and a pseudoaneurysm presenting immediately after TKA. First-line management of acute limb ischemia is currently transitioning from open surgery to endovascular strategies such as catheter-directed thrombolysis or mechanical thrombectomy. Due to the rarity of acute limb ischemia and pseudoaneurysms after TKA, endovascular management is only reported in a few case studies. This case is distinctive by having both popliteal artery thrombosis and a pseudoaneurysm which were successfully managed entirely endovascular using AngioJet thrombolysis and a flexible covered stent. This case contributes to the evidence supporting endovascular management of this rare complication of TKA.

Popliteal Vein Aneurysm: A Rare Cause of Pulmonary Emboli.

Venous aneurysms are a rare pathology that was first reported in the literature in 1968. Popliteal venous aneurysms (PVAs) are the most common lower limb venous aneurysm and have significant consequences including deep vein thrombosis, pulmonary embolus (PE), and death. A 52-year-old woman presented with chest pain and shortness of breath. A computed tomography (CT) angiography demonstrated bilateral pulmonary emboli, and she was commenced on rivaroxaban. History revealed no significant risk factors, and a thrombophilia screen was negative. However, an aneurysmal popliteal vein as seen on an ultrasound scan that was further clarified with CT venography. She underwent an uncomplicated open tangential resection and lateral venorrhaphy. The diagnosis of PVA is usually made incidentally during investigations for pulmonary embolism or chronic venous insufficiency. Surgery is indicated in all symptomatic patients with PE as anticoagulation alone is inadequate in these patients. Surgery is also recommended in patients with asymptomatic saccular aneurysms or large (>20 mm) fusiform aneurysms. The current mainstay of treatment for PVAs is open surgical management.

Generation of tunable octave-spanning mid-infrared pulses by filamentation in gas media.

The continued development of femtosecond mid-infrared (IR) sources with ultrabroad spectral width is critical for probing and controlling complex molecular structural dynamics on an ultrafast timescale. We report on a sub-20 fs, coherent mid-IR source with an octave-spanning spectral bandwidth (>2000 cm(-1)) tunable from 2-8 micrometers (37.5-150 THz), with energy >0.4 µJ/pulse at 1 kHz. The mid-IR pulses are generated by four-wave mixing during the filamentation of intense 800 nm and 400 nm pulses in various gas media. Spectral tunability is achieved by the choice of gas, pressure and input 800 nm pulse energy.

Reduction of spin diffusion artifacts from 2D zfr-INADEQUATE MAS NMR spectra.

The primary shortcoming of the z-filtered refocused INADEQUATE MAS NMR pulse sequence is the possibility of artifacts introduced during the z-filter due to spin diffusion where by extra peaks in the single-quantum dimension (from other sites in the molecule) appear correlated with a given double-quantum frequency. This is a problem when the spinning speeds are too slow (less than 15 kHz) to sufficiently average the proton-proton homonuclear dipolar couplings. This would be especially important when working with large volume rotors that are difficult to spin fast enough to completely average the homonuclear couplings. In our experiments we used the frequency-switched Lee-Goldberg (FSLG) method of homonuclear decoupling during the z-filter to remove the artifact peaks. This method has the advantage of being quite easy to setup and implement on most modern NMR spectrometers.

Reinforcing mechanisms of single-walled carbon nanotube-reinforced polymer composites.

The reinforcing mechanisms of single-walled carbon nanotube-reinforced epoxy composites were studied by micromechanics models. The modeling results obtained from both Halpin-Tsai and Mori-Tanaka models are in good agreement with the experimental results. It has been found that these two models are also applicable to other single-walled carbon nanotube-reinforced, amorphous-polymer composites, given the existence of efficient load transfer. The reinforcing mechanisms that work in polymer-carbon nanotube composites were studied. The reasons responsible for the low mechanical property enhancement of single-walled carbon nanotube in polymer composites were discussed in conjunction with the effective fiber length concept, interface between nanotube bundles and the matrix, properties of the reinforcements and matrix, bundle effects, bundle curvature, and alignment.

Structural and mechanical characterization of nanoclay-reinforced agarose nanocomposites.

Nanoclay-reinforced agarose nanocomposite films with varying weight concentration ranging from 0 to 80% of nanoclay were prepared, and structurally and mechanically characterized. Structural characterization was carried out by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). It was found that pre-exfoliated clay platelets were re-aggregated into particles (stacked platelets) during the composite preparation process. Each particle consists of approximately 11 clay platelets stacked together. The nanoclay particles were homogeneously dispersed within an agarose matrix. The clay particles were oriented with a slight preference of the stacked platelets being parallel to the composite film's surface within the low loading composite films. Mechanical properties of the nanocomposite films were measured by tensile, three-point bending and nanoindentation tests. Mechanical testing results show that nanoclays provide a significant enhancement to the tensile modulus and strength. For the 60% clay nanocomposite, its elastic modulus increases up to 21.4 GPa, which is five times higher than that of the agarose matrix. Based upon the structural characterization, a theoretical model has been developed to simulate the mechanical behaviour of the nanoclay-reinforced polymer composites.

Parathyroid hormone and its fragments in children with chronic renal failure.

Parathyroid hormone (PTH) immunoradiometric assays (IRMA) exhibit cross-reactivity between 1-84 PTH and long carboxyl-terminal-PTH (C-PTH) molecules. C-PTH antagonizes the biological actions of 1-84 PTH and circulates in excess in chronic renal failure (CRF), partially explaining why supra-physiological PTH levels are recommended to maintain bone turnover. Furthermore, the ratio 1-84 PTH/C-PTH may be related to bone turnover. This study characterizes the 1-84 PTH/C-PTH ratio in children with varying severity of CRF and levels of PTH. Two hundred and forty-one children with CRF, managed with the aim of preventing the development of hyperparathyroidism, had PTH measured by 'intact' IRMA and a new more specific Cyclase-Activating-PTH (CAP) IRMA. C-PTH levels were calculated by subtracting CAP-IRMA from 'intact' IRMA. Fifty-three controls with normal renal function were also recruited. Mean 'intact' IRMA correlated with CAP-IRMA ( r=0.98), but was higher ( P<0.001). The mean 1-84 PTH/C-PTH ratio was lower than controls in dialysis patients ( P=0.022) and those with a glomerular filtration rate <30 ml/min per m(2 )( P=0.033). This ratio was comparable to controls when the PTH level was normal, but was lower with PTH levels outside the normal range ( P<0.01). These data suggest that CAP-IRMA gives a more accurate assessment of actual PTH levels than 'intact' IRMA in CRF. Maintenance of normal PTH levels throughout the course of CRF permits the maintenance of a normal 1-84 PTH/C-PTH ratio, the clinical significance of which requires further investigation in children.