Fluid inertia controls mineral precipitation and clogging in pore to network-scale flows.

Mineral precipitation caused by fluid mixing presents complex control and predictability challenges in a variety of natural and engineering processes, including carbon mineralization, geothermal energy, and microfluidics. Precipitation dynamics, particularly under the influence of fluid flow, remain poorly understood. Combining microfluidic experiments and three-dimensional reactive transport simulations, we demonstrate that fluid inertia controls mineral precipitation and clogging at flow intersections, even in laminar flows. We observe distinct precipitation regimes as a function of Reynolds number (Re). At low Reynolds numbers (Re < 10), precipitates form a thin, dense layer along the mixing interface, which shuts precipitation off, while at high Reynolds numbers (Re > 50), strong three-dimensional flows significantly enhance precipitation over the entire intersection, resulting in rapid clogging. When injection rates from two inlets are uneven, flow symmetry-breaking leads to unexpected flow bifurcation phenomena, which result in enhanced concurrent precipitation in both downstream channels. Finally, we extend our findings to rough channel networks and demonstrate that the identified inertial effects on precipitation at the intersection scale are also present and even more dramatic at the network scale. This study sheds light on the fundamental mechanisms underlying mixing-induced mineral precipitation and provides a framework for designing and optimizing processes involving mineral precipitation.

Semiconducting hematite facilitates microbial and abiotic reduction of chromium.

Semi-conducting Fe oxide minerals, such as hematite, are well known to influence the fate of contaminants and nutrients in many environmental settings through sorption and release of Fe(II) resulting from microbial or abiotic reduction. Studies of Fe oxide reduction by adsorbed Fe(II) have demonstrated that reduction of Fe(III) at one mineral surface can result in the release of Fe(II) on a different one. This process is termed "Fe(II) catalyzed recrystallization" and is believed to be the result of electron transfer through semi-conducting Fe (hydr)oxides. While it is well understood that Fe(II) plays a central role in redox cycling of elements, the environmental implications of Fe(II) catalyzed recrystallization require further exploration. Here, we demonstrate that hematite links physically separated redox reactions by conducting the electrons involved in those reactions. This is shown using an electrochemical setup where Cr reduction is coupled with a potentiostat or Shewanella putrefaciens, a metal reducing microbe, where electrons donated to hematite produce Fe(II) that ultimately reduces Cr. This work demonstrates that mineral semi-conductivity may provide an additional avenue for redox chemistry to occur in natural soils and sediments, because these minerals can link redox active reactants that could not otherwise react due to physical separation.

52-year-old man • syncopal episode • chest pain • mild lightheadedness • Dx?

► Syncopal episode ►Chest pain ► Mild lightheadedness.

Cardiovascular Complications of Acetylcholinesterase Inhibitors in Patients with Alzheimer's Disease: A Narrative Review.

While acetylcholinesterase inhibitors are used to treat a wide range of patients with Alzheimer's disease, acetylcholinesterase inhibitor use has also been associated with a variety of cardiovascular complications, including bradycardia and syncope. Herein, we review the pathophysiology and clinical evidence for cardiovascular complications caused by acetylcholinesterase inhibitors in patients being treated for dementia and discuss options for their management.

A case of premature ventricular contractions-related cardiomyopathy.

Premature ventricular contractions (PVCs) are heart beats initiated in the ventricles instead of in the sinoatrial node. A high burden of PVCs can lead to a cardiomyopathy, characterised by reduced left ventricular (LV) systolic dysfunction. We present a case of PVC-related cardiomyopathy where the 65-year-old male was initially seen by his primary care provider for recent onset chest pain and dizziness. His transthoracic echocardiogram showed mild concentric LV hypertrophy and mildly reduced systolic function (LV ejection fraction 43%). There was also mild right ventricular (RV) systolic dysfunction. He was started on a beta-blocker and an angiotensin-converting enzyme inhibitor. A 24-hour Holter monitor showed a very high burden of PVCs (32% of all beats). He continued to have frequent PVCs and his echocardiogram did not improve. He was eventually referred for a PVC ablation. Following the ablation, a repeat Holter monitor showed a marked reduction in PVC burden (<1% of beats) and his echocardiogram had normalised.

An Unusual Case of Shock in an Octogenarian.

An octogenarian presented to our hospital in shock after being "found down" at home. She was dehydrated, hypernatremic, and suffering from a urinary tract infection. Findings of a murmur and those on electrocardiography led to the performance of echocardiography, with all findings consistent with a diagnosis of hypertrophic obstructive cardiomyopathy. The patient was volume resuscitated and administered antibiotics; after stabilization, she was started on a low-dose beta-blocker. Hypertrophic cardiomyopathy is a common genetic disorder that is usually diagnosed in the second to fifth decades of life. It is an uncommon cause or contributor to shock and is unusually initially diagnosed at an advanced age. We briefly review the diagnosis and management of hypertrophic cardiomyopathy in older adults, particularly in the setting of shock.

Development of a novel microfluidic device to study metal geochemistry in situ using X-ray fluorescence microprobe spectroscopy.

The study of in situ microscale biogeochemical processes represents a major challenge in the environmental sciences. The combination of microfluidic devices with X-ray fluorescence microprobe spectroscopy may address this need, but typical materials used in these devices attenuate the X-rays needed to analyze key elements of interest, such as Fe or As. In this work, a method is presented for fabricating an etched silicon microfluidic device that is sealed with a 30 µm thin glass window that is sufficiently transparent for X-ray fluorescence microprobe spectroscopy. The capabilities of these devices for X-ray microprobe spectroscopy are demonstrated using an Fe (hydr)oxide solid that is loaded with As and then infused with sulfide, on beamline 4-BM at NSLS-II, resulting in time-variant Fe precipitation reactions and As sorption. Key results include in situ X-ray fluorescence time-series maps of Fe, As and a Br flow tracer, as well as spot XANES at both the Fe K edge and As K edge. Additionally, multiple energy mapping is used to examine the spatial speciation of As over time. The results of this work clearly demonstrate the capabilities of this novel microfluidic system that can be analyzed using X-ray fluorescence microprobe spectroscopy and can be made to study a wide range of complex microscale geochemical systems.

Atherosclerosis, its risk factors, and cognitive impairment in older adults.

OBJECTIVE: To examine the association of atherosclerotic cardiovascular disease (ASCVD) and its risk factors with cognitive impairment in older adults. METHODS: Six hundred and fourteen subjects, aged ≥ 65 years, from one center (2016-2018) underwent clinical, laboratory assessments and the Montreal Cognitive Assessment (MoCA). Using regression analysis, the relationship between ASCVD and its risk factors was evaluated in subjects with and without cognitive impairment (MoCA score < 26). RESULTS: Older age (ß = -1.3 per 5 years, 95% CI: -1.7 to -0.9, P < 0.001), history of stroke (ß = -1.6, 95% CI: -3.0 to -0.3, P = 0.01), and myocardial infarction (MI; ß = -2.2, 95% CI: -3.6 to -0.8, P = 0.003) were independently associated with lower MoCA scores, whereas more education (ß = 1.5 per 3 years, 95% CI: 1.1 to 1.9, P < 0.001), higher body mass index (BMI; ß = 0.5 per 3 kg/m2, 95% CI: 0.0 to 1.0, P = 0.04), higher estimated glomerular filtration rate (eGFR; ß = 0.8 per 15 U, 95% CI: 0.1 to 1.4, P = 0.03), left ventricular ejection fraction (LVEF; ß = 0.4 per 5%, 95% CI: 0 to 0.8, P = 0.04) and statin use (ß = 1.3, 95% CI: 0.3 to 2.3, P = 0.01) were associated with a higher MoCA score. Cognitive impairment was independently associated with older age (OR = 1.51 per 5 yrs, 95% CI: 1.28 to 1.79, P < 0.001), less education (OR = 0.55 per 3 years, 95% CI: 0.45 to 0.68, P < 0.001), lower BMI (OR = 0.78 per 3 kg/m2, 95% CI: 0.62 to 0.98, P = 0.03) and higher levels of high sensitivity c-reactive protein (hsCRP; OR = 1.08 per 1 mg/L, 95% CI: 1.02 to 1.15, P = 0.01). CONCLUSIONS: Beyond age, cognitive impairment was associated with prior MI/stroke, higher hsCRP, statin use, less education, lower eGFR, BMI and LVEF.

Noncompaction cardiomyopathy and multiple coronary-cameral fistulae in an octogenarian.

An 85-year-old man was admitted to the emergency department with chest pain. His electrocardiogram showed a right bundle branch block as well as increased voltages suggesting left ventricular hypertrophy and t-wave inversions consistent with a strain pattern (versus ischemia). He underwent echocardiography which showed regional noncompaction and associated hypokinesis. These findings led to coronary angiography which revealed multiple coronary-cameral fistulae involving all three coronary arteries. He was initially treated for acute coronary syndrome but after his diagnostic procedures this was narrowed to a beta blocker, to reduce myocardial oxygen demand, and an angiotensin-converting enzyme inhibitor due to the cardiomyopathy. Although the fistulae may have caused the patient's chest pain, intervention was not possible due to the diffuse nature of the fistulae. He did well in follow-up without the development of heart failure symptoms or continued angina. .

Radium Sorption to Iron (Hydr)oxides, Pyrite, and Montmorillonite: Implications for Mobility.

Radium (Ra) is a radioactive element commonly found within soils, sediments, and natural waters. Elevated Ra activities arising through natural and anthropogenic processes pose a threat to groundwater resources and human health, and Ra isotope ratios are used to decipher groundwater movement, estimate submarine discharge flux, and fingerprint contamination associated with hydraulic fracturing operations. Although adsorption to metal (hydr)oxides and certain clay minerals is well established as a dominant mechanism controlling Ra transport and retention, the extent of Ra sorption to other minerals and under variable environmental conditions (e.g., pH and salinity) is limited. Accordingly, we present results of sorption studies and surface complexation modeling (SCM) of Ra to ferrihydrite, goethite, montmorillonite, and pyrite, for a range of pH values and common background cations. Ra sorption to all substrates is observed under geochemical conditions considered, but varies according to mineral, solution pH and specific competing cations. Literature derived SCMs for Ra sorption were fitted to match either sorption impacts due to pH or different background cations, but were not able to predict the impacts of different geochemical conditions. Despite this, the use of SCMs provided a more mechanistic understanding of Ra sorption as compared to commonly used distribution coefficients.

Multimorbidity in Older Adults with Atrial Fibrillation.

Older adults with atrial fibrillation often have multiple comorbid conditions, including common geriatric syndromes. Pharmacologic therapy, whether for rate control or rhythm control, can result in complications related to polypharmacy in patients who are often on multiple medications for other conditions. Because of uncertainty about the relative risks and benefits of rate versus rhythm control (including antiarrhythmic or ablation therapy), anticoagulation, and procedural treatments (eg, ablation, left atrial appendage closure, pacemaker placement) in older patients with multimorbidity, shared decision-making is essential. However, this may be challenging in patients with cognitive dysfunction, high fall risk, or advanced comorbidity.

Frailty and cardiovascular disease: potential role of gait speed in surgical risk stratification in older adults.

Frailty is a state of late life decline and vulnerability, typified by physical weakness and decreased physiologic reserve. The epidemiology and pathophysiology of frailty share features with those of cardiovascular disease. Gait speed can be used as a measure of frailty and is a powerful predictor of mortality. Advancing age is a potent risk factor for cardiovascular disease and has been associated with an increased risk of adverse outcomes. Older adults comprise approximately half of cardiac surgery patients, and account for nearly 80% of the major complications and deaths following surgery. The ability of traditional risk models to predict mortality and major morbidity in older patients being considered for cardiac surgery may improve if frailty, as measured by gait speed, is included in their assessment. It is possible that in the future frailty assessment may assist in choosing among therapies (e.g., surgical vs. percutaneous aortic valve replacement for patients with aortic stenosis).

Effect of age on aortic atherosclerosis.

OBJECTIVE: To examine the association of atherosclerosis burden in the survivors of an asymptomatic elderly cohort study and its relationship to other coronary risk factors (specifically, age) by evaluating aortic atherosclerotic wall burden by magnetic resonance imaging (MRI). METHODS: A total of 312 participants in an ongoing observational cohort study underwent cardiac and descending thoracic aorta imaging by MRI. Maximum wall thickness was measured and the mean wall thickness calculated. Wall/outer wall ratio was used as a normalized wall index (NWI) adjusted for artery size difference among participants. Percent wall volume (PWV) was calculated as NWI × 100. RESULTS: IN THIS ASYMPTOMATIC COHORT (MEAN AGE: 76 years), the mean (SD) aortic wall area and wall thickness were 222 ± 45 mm(2) and 2.7 ± 0.4 mm, respectively. Maximum wall thickness was 3.4 ± 0.6 mm, and PWV was 32% ± 4%. Women appeared to have smaller wall area, but after correcting for their smaller artery size, had significantly higher PWV than men (P = 0.03). Older age was associated with larger wall area (P = 0.04 for trend) with similar PWVs. However, there were no statistically significant associations between standard risk factors, Framingham global risk, or metabolic syndrome status, therapy for cholesterol or hypertension, coronary or aortic calcium score, and the aortic wall burden. Aortic calcification was associated with coronary calcification. CONCLUSIONS: Asymptomatic elderly in this cohort had a greater descending thoracic aortic wall volume that correlated with age, and women had a significantly increased PWV compared to men. In these survivors, the atherosclerotic aortic wall burden was not significantly associated with traditional risk factors or with coronary or aortic calcium scores or coronary calcium progression. Results suggest that age, or as yet unidentified risk factor(s), may be responsible for the increase in atherosclerosis.

Transient stress cardiomyopathies in the elderly: Clinical & Pathophysiologic considerations.

Transient stress-induced cardiomyopathies have been increasingly recognized and while rare, they tend to affect elderly women more than other demographic groups. One type, often called tako-tsubo cardiomyopathy (TTC), is typically triggered by significant emotional or physical stress and is associated with chest pain, electrocardiogram (ECG) changes and abnormal cardiac enzymes. Significant left ventricular regional wall motion abnormalities usually include an akinetic "ballooning" apex with normal or hyperdynamic function of the base. A second type, often called neurogenic stunned myocardium, typically associated with subarachnoid hemorrhage, also usually presents with ECG changes and positive enzymes, but the typical wall motion abnormalities seen include normal basal and apical left ventricular contraction with akinesis of the mid-cavity in a circumferential fashion. The pathophysiology, clinical care and typical courses, are reviewed.

Real time three-dimensional echocardiography evaluation of intracardiac masses.

The evaluation of cardiac masses is often a challenge for cardiac imaging techniques. The traditional standby has been two-dimensional echocardiography (2DE). Real time three-dimensional echocardiography (RT3DE) offers incremental value for the evaluation of intracardiac masses by providing more accurate assessment of the size and shape of the mass as well as in some cases, composition of the mass. RT3DE aids with the relationship between the mass and adjacent structures. Therefore, here we discuss the subject of RT3DE evaluation of cardiac masses is reviewed and discussed in detail.

Cor triatriatum evaluated by real time 3D TEE.

We present two cases of cor triatriatum, a rare congenital anomaly that consists of a membrane that divides the left atrium into two chambers. The first case involves an older adult man admitted for evaluation of left-sided weakness attributed to stroke. The second is a case of a middle-aged woman with dyspnea. Both patients had transthoracic echocardiograms as a part of their initial evaluation, which revealed abnormal structures in the left atrium, and both subsequently underwent transesophageal echocardiography. During these exams, real-time 3D imaging was utilized to more completely define the pathology.