Skeletal muscle fitness and physiology as determinants of firefighter performance and safety: a narrative review.

Firefighters routinely perform tasks that are reliant on their muscular fitness, which includes muscular strength, power and endurance. Separately, firefighters can present with unique skeletal muscle physiology characteristics due to the strenuous nature of this occupation. This review aims to summarise muscular fitness and physiology as determinants of a firefighter's ability to perform occupation-specific tasks, identify the relevance of both muscular fitness and physiology to a firefighter's risk for sustaining a work-related injury, and address the contributions of muscular fitness and physiology on a firefighter's ability to recover from tasks and their readiness for performing subsequent or future tasks. The presented evidence reveals muscular fitness can determine a firefighter's capacity to perform their job effectively, while also influencing risk for occupational injury. Collectively, this review indicates exercise training emphasising improvements in muscular strength, power, and endurance (i.e. resistance training) should be encouraged in this occupation.

This review addressed muscular fitness and physiology in firefighters. Current evidence suggests firefighter task performance and risk for injury is associated with high levels of muscular fitness. Additionally, firefighters undergo unique changes in muscle morphology and physiology that can negatively affect the ability to safely perform occupation-specific tasks repeatedly.

Muscle Damage, Inflammation, and Muscular Performance following the Physical Ability Test in Professional Firefighters.

Proper monitoring of fatigue and muscular damage may be used to decrease the high levels of cardiovascular disease, overuse musculoskeletal injuries, and workers compensation claims within the profession of firefighting. The purpose of this study was to examine muscle damage, muscular fatigue, and inflammation responses following a typical firefighting shift. Twenty-four professional firefighters completed two Physical Ability Tests to standardize the tasks typically performed in a day of work, and to elicit similar physiological responses. Participants were then monitored for 48 h. Prior to, and 48 h following the Physical Ability Tests, participants were evaluated for changes in strength, power, range-of-motion, as well as blood markers including myoglobin and c-reactive protein. Following the Physical Ability Tests, significant differences in myoglobin (p < 0.05), grip strength (p < 0.05), vertical jump (p < 0.05), and sit-and-reach (p < 0.05) were observed. No difference in c-reactive protein was observed (p > 0.05). After 24 hours following a shift, firefighters exhibited decreased strength, power, and range-of-motion. This may lead to decreases in performance and an increased risk of injury.

The Natural History of Carotid Artery Occlusions Diagnosed on Duplex Ultrasound.

BACKGROUND: There is a paucity of literature on the natural history of extracranial carotid artery occlusion (CAO). This study reviews the natural history of this patient cohort. METHODS: This single-institution retrospective analysis studied patients with CAO diagnosed by duplex ultrasound between 2010 and 2021. Patients were identified by searching our office-based Intersocietal Accreditation Commission accredited vascular laboratory database. Imaging and clinical data were obtained via our institutional electronic medical record. Outcomes of interest included ipsilateral stroke, attributable neurologic symptoms, and ipsilateral intervention after diagnosis. RESULTS: The full duplex database consisted of 5,523 patients who underwent carotid artery duplex examination during the study period. The CAO cohort consisted of 139 patients; incidence of CAO was 2.5%. Mean age at diagnosis was 69.7 years; 31.4% were female. Hypertension (72.7%), hyperlipidemia (64.7%), and prior smoking (43.9%) were the most common comorbid conditions. Of the CAO cohort, 61.3% (n = 85) of patients were asymptomatic at diagnosis; 38.8% (n = 54) were diagnosed after a stroke or transient ischemic attack occurring within 6 months prior to diagnosis, with 21.6% occurring ipsilateral to the CAO and 10.1% occurring contralateral to the CAO. 7.2% (n = 10) had unclear symptoms or laterality at presentation. Of the CAO cohort, 95 patients (68.3%) had duplex imaging follow-up (mean 42.7 ± 31.3 months). Of those with follow-up studies, 7 patients (5.0%) developed subsequent stroke ipsilateral to the CAO with mean occurrence 27.8 ± 39.0 months postdiagnosis. In addition, 5 patients (3.6%) developed other related symptoms, including global hypoperfusion (2.4%) and transient ischemic attack (1.2%). Of those, 95 patients with follow-up duplex ultrasound imaging, 6 (4.3%) underwent eventual ipsilateral intervention, including carotid endarterectomy (n = 4), transfemoral carotid artery stent (n = 1), and carotid bypass (n = 1), with mean occurrence 17.7 ± 23.7 months postdiagnosis. The aggregate rate of ipsilateral cerebrovascular accident, attributable neurologic symptoms, or ipsilateral intervention was 11.5%. Of 95 patients with follow-up duplex ultrasound imaging, 5 underwent subsequent duplex studies demonstrating ipsilateral patency, resulting in a 5.3% discrepancy rate between sequential duplex studies. All 6 patients undergoing intervention received periprocedural cross-sectional imaging (magnetic resonance angiography or computed tomography angiography). In 5 of these 6 patients, cross-sectional demonstrated severe stenosis rather than CAO, disputing prior duplex ultrasound findings. CONCLUSIONS: In this large, institutional cohort of patients with a CAO diagnosis on duplex ultrasound, a clinically meaningful subset of patients experienced cerebrovascular accident, related symptoms, or intervention. We also found a notable rate of temporal duplex discrepancies among patients with CAO diagnoses and discrepancies between CAO diagnosis per duplex ultrasound and findings on cross-sectional imaging for those patients who underwent intervention. These results suggest that use of a single duplex ultrasound as a sole diagnostic tool in CAO may not be sufficient and that physicians should consider close duplex ultrasound surveillance of these patients, potentially in conjunction with additional confirmatory imaging modalities. Further investigation into optimal workup and surveillance protocols for CAO is needed.

Whey protein improves glycemia during an oral glucose tolerance test compared to vigorous-intensity aerobic exercise in young adult men.

BACKGROUND: Both aerobic exercise and whey protein can improve glucose regulation. The purpose of this study was to investigate how a single bout of vigorous-intensity aerobic exercise and whey protein, independently, as well as when combined, influence glycemia during an oral glucose tolerance test in sedentary, young men. METHODS: Healthy males (n = 11) completed four randomized trials: no exercise/no whey protein (R); exercise (EX; walking at 70% VO2max for 60 min); 50 g of whey protein (W); and exercise combined with 50 g of whey protein (EXW). Each trial included a 75 g oral glucose tolerance test (OGTT) that was completed after an overnight fast. Blood samples were collected over a two-hour period during the OGTT. For EX and EXW, the exercise was performed the evening before the OGTT and the 50 g of whey protein was dissolved in 250 mL of water and was consumed as a preload 30 min prior to the OGTT. For R and EX, participants consumed 250 mL of water prior to the OGTT. Plasma samples were analyzed for glucose, insulin, C-peptide, glucagon, gastric inhibitory peptide (GIP) and glucagon like peptide 1 (GLP-1), and postprandial incremental area under the curve (iAUC) was calculated for each. RESULTS: Glucose iAUC was reduced during W (- 32.9 ± 22.3 mmol/L) compared to R (122.7 ± 29.8 mmol/L; p < 0.01) and EX (154.3 ± 29.2 mmol/L; p < 0.01). Similarly, glucose iAUC was reduced for EXW (17.4 ± 28.9 mmol/L) compared to R and EX (p < 0.01 for both). There were no differences in iAUC for insulin, C-peptide, GIP, GLP-1, and glucagon between the four trials. Insulin, C-peptide, glucagon, GIP, and GLP-1 were elevated during the whey protein preload period for W and EXW compared to EX and R (p < 0.01). There were no differences for insulin, C-peptide, glucagon, GIP, or GLP-1 between trials for the remaining duration of the OGTT. CONCLUSIONS: Glucose responses during an oral glucose tolerance test were improved for W compared to EX. There were no additional improvements in glucose responses when vigorous-intensity aerobic exercise was combined with whey protein (EXW).

A multiparametric calcium signal screening platform using iPSC-derived cortical neural spheroids.

Discovery of therapeutics for neurological diseases is hampered by the lack of predictive in vitro and in vivo models. Traditionally, in vitro assays rely on engineered cell lines grown two-dimensionally (2D) outside a physiological tissue context, which makes them very amenable for large scale drug screening but reduces their relevance to in vivo neurophysiology. In recent years, three-dimensional (3D) neural cell culture models derived from human induced pluripotent stem cells (iPSCs) have been developed as an in vitro assay platform to investigate brain development, neurological diseases, and for drug screening. iPSC-derived neural spheroids or organoids can be developed to include complex neuronal and glial cell populations and display spontaneous, synchronous activity, which is a hallmark of in vivo neural communication. In this report we present a proof-of-concept study evaluating 3D iPSC-derived cortical neural spheroids as a physiologically- and pharmacologically-relevant high-throughput screening (HTS) platform and investigate their potential for use for therapeutic development. To this end, a library of 687 neuroactive compounds were tested in a phenotypic screening paradigm which measured calcium activity as a functional biomarker for neural modulation through fluctuations in calcium fluorescence. Pharmacological responses of cortical neural spheroids were analyzed using a multi-parametric approach, whereby seven peak characteristics from the calcium activity in each well were quantified and incorporated into principal component analysis and Sammon mapping to measure compound response. Here, we describe the implementation of the 687-compound library screen and data analysis demonstrating that iPSC-derived cortical spheroids are a robust and information-rich assay platform for HTS.

Survey analysis of exercise participation and skeletal muscle symptoms in women with hypothyroidism.

This study examined the effect of exercise on skeletal muscle symptoms experienced by women with hypothyroidism. An online survey on exercise participation was completed by female participants undergoing treatment for hypothyroidism (n = 580). Basal muscle symptoms (MS) and exercise muscle symptoms were analyzed by the type of exercise performed, cardiovascular/aerobic (CV), resistance training (RT), or both (CVRT). Exercise participation affected MS (F = 7.186, p < .01) with respondents performing a combination of CVRT reporting the lowest basal MS compared to those performing CV (p = .044), RT (p = .031) alone, or those performing no exercise at all (p < .001). Associations between muscle pain (χ2 = 7.963, p = .019) and muscle fatigue (χ2 = 14.240, p < .001) during exercise and by exercise type were found. Muscle pain during exercise was also associated with an exercise type and frequency (χ2 = 24.164, p < .019). Finally, there was an association between recovery from exercise and frequency of exercise bouts (χ2 = 32.185, p < .001). Women with hypothyroidism commonly experience skeletal muscle symptoms at rest and during exercise. The results from this study indicate the type of exercise performed may have an impact on the occurrence of these symptoms.

Bone-on-a-chip: microfluidic technologies and microphysiologic models of bone tissue.

Bone is an active organ that continuously undergoes an orchestrated process of remodeling throughout life. Bone tissue is uniquely capable of adapting to loading, hormonal, and other changes happening in the body, as well as repairing bone that becomes damaged to maintain tissue integrity. On the other hand, diseases such as osteoporosis and metastatic cancers disrupt normal bone homeostasis leading to compromised function. Historically, our ability to investigate processes related to either physiologic or diseased bone tissue has been limited by traditional models that fail to emulate the complexity of native bone. Organ-on-a-chip models are based on technological advances in tissue engineering and microfluidics, enabling the reproduction of key features specific to tissue microenvironments within a microfabricated device. Compared to conventional in-vitro and in-vivo bone models, microfluidic models, and especially organs-on-a-chip platforms, provide more biomimetic tissue culture conditions, with increased predictive power for clinical assays. In this review, we will report microfluidic and organ-on-a-chip technologies designed for understanding the biology of bone as well as bone-related diseases and treatments. Finally, we discuss the limitations of the current models and point toward future directions for microfluidics and organ-on-a-chip technologies in bone research.

Changes in Health and Physical Fitness Parameters After Six Months of Group Exercise Training in Firefighters.

Proper training methods may be used as an effective preventative measure for many of the musculoskeletal injuries sustained as a first responder that are inherent to the profession. The traditionally low fitness levels and poor exercise habits of city firefighters may predispose this population to an increased risk of chronic conditions, such as cardiovascular and metabolic disease. The purpose of this study was to analyze changes in the health and fitness parameters of professional firefighters across North Texas during a six-month training program. Twenty-two professional firefighters completed six months of group training, consisting of two training sessions per week. These individuals underwent a pre- and post-fitness testing protocol that consisted of body composition, range of motion, anaerobic power, muscular endurance, and cardiorespiratory fitness. Improvements (p < 0.05) in flexibility, anaerobic performance, fatigue index, muscular endurance, and aerobic fitness were found following the six-month training program. No differences in body composition or peak power were observed (p > 0.05). Six months of group exercise improves aerobic and anaerobic fitness, exercise tolerance, muscular endurance, and flexibility in firefighters.

A Multifunctional Therapy Approach for Cancer: Targeting Raf1- Mediated Inhibition of Cell Motility, Growth, and Interaction with the Microenvironment.

Prostate cancer cells move from their primary site of origin, interact with a distant microenvironment, grow, and thereby cause death. It had heretofore not been possible to selectively inhibit cancer cell motility. Our group has recently shown that inhibition of intracellular activation of Raf1 with the small-molecule therapeutic KBU2046 permits, for the first time, selective inhibition of cell motility. We hypothesized that simultaneous disruption of multiple distinct functions that drive progression of prostate cancer to induce death would result in advanced disease control. Using a murine orthotopic implantation model of human prostate cancer metastasis, we demonstrate that combined treatment with KBU2046 and docetaxel retains docetaxel's antitumor action, but provides improved inhibition of metastasis, compared with monotherapy. KBU2046 does not interfere with hormone therapy, inclusive of enzalutamide-mediated inhibition of androgen receptor (AR) function and cell growth inhibition, and inclusive of the ability of castration to inhibit LNCaP-AR cell outgrowth in mice. Cell movement is necessary for osteoclast-mediated bone degradation. KBU2046 inhibits Raf1 and its downstream activation of MEK1/2 and ERK1/2 in osteoclasts, inhibiting cytoskeleton rearrangement, resorptive cavity formation, and bone destruction in vitro, with improved effects observed when the bone microenvironment is chemically modified by pretreatment with zoledronic acid. Using a murine cardiac injection model of human prostate cancer bone destruction quantified by CT, KBU2046 plus zoledronic exhibit improved inhibitory efficacy, compared with monotherapy. The combined disruption of pathways that drive cell movement, interaction with bone, and growth constitutes a multifunctional targeting strategy that provides advanced disease control.

Rapid fabrication of vascularized and innervated cell-laden bone models with biomimetic intrafibrillar collagen mineralization.

Bone tissue, by definition, is an organic-inorganic nanocomposite, where metabolically active cells are embedded within a matrix that is heavily calcified on the nanoscale. Currently, there are no strategies that replicate these definitive characteristics of bone tissue. Here we describe a biomimetic approach where a supersaturated calcium and phosphate medium is used in combination with a non-collagenous protein analog to direct the deposition of nanoscale apatite, both in the intra- and extrafibrillar spaces of collagen embedded with osteoprogenitor, vascular, and neural cells. This process enables engineering of bone models replicating the key hallmarks of the bone cellular and extracellular microenvironment, including its protein-guided biomineralization, nanostructure, vasculature, innervation, inherent osteoinductive properties (without exogenous supplements), and cell-homing effects on bone-targeting diseases, such as prostate cancer. Ultimately, this approach enables fabrication of bone-like tissue models with high levels of biomimicry that may have broad implications for disease modeling, drug discovery, and regenerative engineering.

Consecutive days of exercise decrease insulin response more than a single exercise session in healthy, inactive men.

PURPOSE: It is reported that a single bout of exercise can lower insulin responses 12-24 h post-exercise; however, the insulin responses to alternate or consecutive bouts of exercise is unknown. Thus, the purpose of this study was to examine the effect of exercise pattern on post-exercise insulin and glucose responses following a glucose challenge. METHODS: Ten male participants (n = 10, mean ± SD, Age 29.5 ± 7.7 years; BMI 25.7 ± 3.0 kg/m2) completed three exercise trials of walking for 60 min at ~ 70% of VO2max. The trials consisted of: three consecutive exercise days (3CON), three alternate exercise days (3ALT), a single bout of exercise (SB), and a no exercise control (R). Twelve to fourteen hours after the last bout of exercise or R, participants completed a 75 g oral glucose tolerance test (OGTT) and blood was collected at 30 min intervals for the measurement of glucose, insulin, and C-peptide. RESULT: Calculated incremental area under the curve (iAUC) for glucose and C-peptide was not different between the four trials. Insulin iAUC decreased 34.9% for 3CON compared to R (p < 0.01). CONCLUSION: Three consecutive days of walking at ~ 70% VO2max improved insulin response following an OGTT compared to no exercise. It is possible, that for healthy males, the effect of a single bout of exercise or exercise bouts separated by more than 24 h may not be enough stimulus to lower insulin responses to a glucose challenge.

Genistein treatment duration effects biomarkers of cell motility in human prostate.

BACKGROUND: Long term dietary consumption of genistein by Chinese men is associated with decreased PCa metastasis and mortality. Short term treatment of US men with prostate cancer (PCa) with genistein decreases MMP-2 in prostate tissue. MEK4 regulates MMP-2 expression, drives PCa metastasis, and genistein inhibits MEK4, decreases MMP-2 expression and dietary dosing inhibits human PCa metastasis in mice. This study examines short- versus long-term treatment effects of genistein in humans and in vitro. METHODS AND FINDINGS: US men with localized PCa were treated on a phase II trial with genistein (N = 14) versus not (N = 14) for one month prior to radical prostatectomy. Prostate epithelial cells were removed from fresh frozen tissue by laser capture microdissection, and the expression of 12,000 genes profiled. Genistein significantly altered the expression of four genes, three had established links to cancer cell motility and metastasis. Of these three, one was a non-coding transcript, and the other two were BASP1 and HCF2. Genistein increased BASP1 expression in humans, and its engineered over expression and knockdown demonstrated that it suppressed cell invasion in all six human prostate cell lines examined. Genistein decreased HCF2 expression in humans, and it was shown to increase cell invasion in all cell lines examined. The expression of MMP-2, MEK4 and BASP1 was then measured in formalin fixed prostate tissue from N = 38 Chinese men living in China and N = 41 US men living in the US, both cohorts with localized PCa. MMP-2 was 52% higher in Chinese compared to US tissue (P < 0.0001), MEK4 was 48% lower (P < 0.0001), and BASP1 was unaltered. Treatment of PC3 human PCa cells in vitro for up to 8 weeks demonstrated that short term genistein treatment decreased MMP-2, while long term treatment increased it, both changes being significant (P<0.05) compared to untreated control cells. Long term genistein-treated cells retained their responsiveness to genistein's anti-motility effect. CONCLUSIONS: Genistein inhibits pathways in human prostate that drive transformation to a lethal high motility phenotype. Long term treatment induces compensatory changes in biomarkers of efficacy. The current strategy of using such biomarkers after short term intervention as go/no-go determinants in early phase chemoprevention trials should be carefully examined.

Synthesis and Biological Evaluation of 3-Arylindazoles as Selective MEK4 Inhibitors.

Herein we report the discovery of a novel series of highly potent and selective mitogen-activated protein kinase kinase 4 (MEK4) inhibitors. MEK4 is an upstream kinase in MAPK signaling pathways that phosphorylates p38 MAPK and JNK in response to mitogenic and cellular stress queues. MEK4 is overexpressed and induces metastasis in advanced prostate cancer lesions. However, the value of MEK4 as an oncology target has not been pharmacologically validated because selective chemical probes targeting MEK4 have not been developed. Optimization of this series via structure-activity relationships and molecular modeling led to the identification of compound 6 ff (4-(6-fluoro-2H-indazol-3-yl)benzoic acid), a highly potent and selective MEK4 inhibitor. This series of inhibitors is the first of its kind in both activity and selectivity and will be useful in further defining the role of MEK4 in prostate and other cancers.

Functional and Mechanistic Neurotoxicity Profiling Using Human iPSC-Derived Neural 3D Cultures.

Neurological disorders affect millions of people worldwide and appear to be on the rise. Whereas the reason for this increase remains unknown, environmental factors are a suspected contributor. Hence, there is an urgent need to develop more complex, biologically relevant, and predictive in vitro assays to screen larger sets of compounds with the potential for neurotoxicity. Here, we employed a human induced pluripotent stem cell (iPSC)-based 3D neural platform composed of mature cortical neurons and astrocytes as a model for this purpose. The iPSC-derived human 3D cortical neuron/astrocyte co-cultures (3D neural cultures) present spontaneous synchronized, readily detectable calcium oscillations. This advanced neural platform was optimized for high-throughput screening in 384-well plates and displays highly consistent, functional performance across different wells and plates. Characterization of oscillation profiles in 3D neural cultures was performed through multi-parametric analysis that included the calcium oscillation rate and peak width, amplitude, and waveform irregularities. Cellular and mitochondrial toxicity were assessed by high-content imaging. For assay characterization, we used a set of neuromodulators with known mechanisms of action. We then explored the neurotoxic profile of a library of 87 compounds that included pharmaceutical drugs, pesticides, flame retardants, and other chemicals. Our results demonstrated that 57% of the tested compounds exhibited effects in the assay. The compounds were then ranked according to their effective concentrations based on in vitro activity. Our results show that a human iPSC-derived 3D neural culture assay platform is a promising biologically relevant tool to assess the neurotoxic potential of drugs and environmental toxicants.

Counterion Effects on Aggregate Structure of 12-Hydroxystearate Salts in Hexane: A Quantum Mechanical and Molecular Dynamics Simulation Study.

Salts of 12-hydroxystearate are important organogelators and grease thickeners, but a structural rationale for their rheological properties remains elusive. We use quantum mechanical calculations and molecular dynamics (MD) simulations to analyze aggregate structures for (1) ( R)-12-hydroxystearic acid (( R)-12HSA), (2) lithium ( R)-12-hydroxystearate (( R)-Li12HS), and (3) sodium ( R)-12-hydroxystearate (( R)-Na12HS). First, quantum mechanical calculations were used to establish the structure and complexation energies of dimers of acetic acid, lithium acetate, and sodium acetate. The expected acetic acid dimer is predicted, and both the lithium acetate and sodium acetate dimer formed a C2 h-symmetric structure. All dimers were sufficiently stable to allow modeling them as pseudocovalent complexes in all-atom, explicit solvent MD. After microsecond-long MD, all systems produced strong ringlike ordered nuclei. The C2 h lithium salt molecules produced aggregates that had the most efficient packing at the head group and a higher frequency of hydroxyl hydrogen bonding compared to the sodium salt. This ordering propensity explains the high melting temperature of ( R)-Li12HS. Also, the higher frequency of hydrogen bonding leads to fewer solvent-exposed hydrogen bond partners. This explains why lithium is a common counterion in high-temperature and water-resistant greases.

Precision therapeutic targeting of human cancer cell motility.

Increased cancer cell motility constitutes a root cause of end organ destruction and mortality, but its complex regulation represents a barrier to precision targeting. We use the unique characteristics of small molecules to probe and selectively modulate cell motility. By coupling efficient chemical synthesis routes to multiple upfront in parallel phenotypic screens, we identify that KBU2046 inhibits cell motility and cell invasion in vitro. Across three different murine models of human prostate and breast cancer, KBU2046 inhibits metastasis, decreases bone destruction, and prolongs survival at nanomolar blood concentrations after oral administration. Comprehensive molecular, cellular and systemic-level assays all support a high level of selectivity. KBU2046 binds chaperone heterocomplexes, selectively alters binding of client proteins that regulate motility, and lacks all the hallmarks of classical chaperone inhibitors, including toxicity. We identify a unique cell motility regulatory mechanism and synthesize a targeted therapeutic, providing a platform to pursue studies in humans.

Effects of Optical Purity and Finite System Size on Self-Assembly of 12-Hydroxystearic Acid in Hexane: Molecular Dynamics Simulations.

12-Hydroxystearic acid (12HSA) and its derivatives are well-known organogelators, and they play critical roles in a variety of applications. The overall aggregate structure of 12HSA is sensitive to the chirality at the 12th carbon, but a fundamental understanding of this dependence is lacking. In this study, molecular dynamics simulations were conducted on microsecond long time scales for (1) (R)-12HSA, (2) (S)-12HSA, and (3) a 50/50 racemic mixture, each solvated at 12.5 wt % in explicit hexane. Self-assembly was accelerated by turning off alkyl chain dihedral gauche states and forcing the molecules to adopt an all-trans conformation. The stability of the resulting aggregates was tested by quenching them with access to gauche states restored. Ordered aggregates produced from optically pure (R)- and (S)-12HSA remained stable for at least 1 µs. The characteristic ordered structure observed is termed a "ring-of-rings" motif, and it contains two twisted six-membered ringlike bundles connected through acetic acid dimerization and surrounded by six satellite bundles. The chirality at the 12th carbon dictates the overall twist of the rings and thereby the handedness of the aggregates. Racemic mixtures did not produce stable ordered aggregates likely due to insufficient enantiomerically pure ring formation. The most prevalent finite-size effect observed was the stochastic formation of percolating aggregates, which were later avoided by using solvent-permeable, solute-impermeable, confining walls. The resulting ordered aggregates were in all important ways identical to those produced in unconfined systems. The combination of cycling off and on gauche states and the semipermeable walls may be an important new way to study the self-assembly underlying aggregation at industrially relevant concentrations of surfactants in organic solvents.

Using Diurnal Temperature Signals to Infer Vertical Groundwater-Surface Water Exchange.

Heat is a powerful tracer to quantify fluid exchange between surface water and groundwater. Temperature time series can be used to estimate pore water fluid flux, and techniques can be employed to extend these estimates to produce detailed plan-view flux maps. Key advantages of heat tracing include cost-effective sensors and ease of data collection and interpretation, without the need for expensive and time-consuming laboratory analyses or induced tracers. While the collection of temperature data in saturated sediments is relatively straightforward, several factors influence the reliability of flux estimates that are based on time series analysis (diurnal signals) of recorded temperatures. Sensor resolution and deployment are particularly important in obtaining robust flux estimates in upwelling conditions. Also, processing temperature time series data involves a sequence of complex steps, including filtering temperature signals, selection of appropriate thermal parameters, and selection of the optimal analytical solution for modeling. This review provides a synthesis of heat tracing using diurnal temperature oscillations, including details on optimal sensor selection and deployment, data processing, model parameterization, and an overview of computing tools available. Recent advances in diurnal temperature methods also provide the opportunity to determine local saturated thermal diffusivity, which can improve the accuracy of fluid flux modeling and sensor spacing, which is related to streambed scour and deposition. These parameters can also be used to determine the reliability of flux estimates from the use of heat as a tracer.

Aggregation of 12-Hydroxystearic Acid and Its Lithium Salt in Hexane: Molecular Dynamics Simulations.

12-Hydroxystearic acid (12HSA) is a well-known organogelator, and its metal salts and derivatives find roles in many important applications. The structures of aggregates of 12-hydroxysteric acid and its salts depend sensitively on cation type, but a fundamental understanding of this phenomenon is lacking. In this study, molecular dynamics simulations were conducted on the microsecond long time scales for (1) 12HSA and (2) its lithium salt, each at 12.5 wt % in explicit hexane solvent. Self-assembly was accelerated by using a modified potential to prohibit alkane chain dihedral gauche states (all-trans-12HSA) and then verified by continuation using standard force-field parameters. In three independent simulation, acceleration using "gauche-less" potentials resulted in self-assembled pseudocrystalline aggregates through formation of polarized five- and six-membered rings between inter-12-hydroxyl groups and head-to-head carboxylic acid dimerization. When subjected to the unmodified dihedral potential, two of the three structures remained stable after 1 µs of MD. Stable structures exhibited a "ring-of-rings" motif, composed of two six-membered acetic acid-dimerized ring bundles with six satellite rings, while the unstable structure did not. In strong contrast, the lithium salt produced a network of fibrils that spanned the volume of the sample. When lithium ions were substituted for carboxylic acid protons in the stable acid structures, they remained intact but lost their chiral nature. Both the acid and lithium structures displayed scattering peaks that agreed with experiment. Taken together, our results suggest that this ring-of-rings structure could be a primary feature of the self-assembly of 12HSA in organic solvents.

Using eye tracking and gaze pattern analysis to test a "dirty bomb" decision aid in a pilot RCT in urban adults with limited literacy.

BACKGROUND: Eye tracking is commonly used in marketing to understand complex responses to materials, but has not been used to understand how low-literacy adults access health information or its relationship to decision making. METHODS: This study assessed how participants use a literacy appropriate "dirty bomb" decision aid. Participants were randomized to receive a CDC "factsheet" (n = 21) or literacy-appropriate aid (n = 29) shown on a computer screen. Using 7 content similar slides, gaze patterns, mean pupil fixation time and mean overall time reading and looking at slides were compared. Groups were also compared by literacy level and effect on 'confidence of knowledge' and intended behavior. RESULTS: Results revealed differing abilities to read densely written material. Intervention participants more precisely followed text on 4 of 7 content-similar slides compared to control participants whose gaze patterns indicated unread text, or repeated attempts at reading the same text, suggesting difficulty in understanding key preparedness messages. Controls had significantly longer pupil fixations on 5 of 7 slides and spent more overall time on every slide. In those with very low literacy, intervention participants were more likely than controls to say they understood what a "dirty bomb" is and how to respond if one should occur. CONCLUSIONS: Results indicate limited- literacy adults, especially those with very low literacy, may not be able to understand how to respond during a "dirty bomb" using available materials, making them vulnerable to negative health events. This study provides insights into how individuals perceive and process risk communication messages, illustrating a rich and nuanced understanding of the qualitative experience of a limited literacy population with written materials. It also demonstrates the feasibility of using these methods on a wider scale to develop more effective health and risk communication messages designed to increase knowledge of and compliance with general health guidelines, and enhance decision making. This has application for those with learning disabilities, those with limited media-literacy skills, and those needing to access the diverse array of assistive technologies now available. Eye tracking is thus a practical approach to understanding these diverse needs to ensure the development of cogent and salient communication.