Prediction of the aggregation rate of nanoparticles in porous media in the diffusion-controlled regime.

The fate and aggregation of nanoparticles (NPs) in the subsurface are important due to potentially harmful impacts on the environment and human health. This study aims to investigate the effects of flow velocity, particle size, and particle concentration on the aggregation rate of NPs in a diffusion-limited regime and build an equation to predict the aggregation rate when NPs move in the pore space between randomly packed spheres (including mono-disperse, bi-disperse, and tri-disperse spheres). The flow of 0.2 M potassium chloride (KCl) through the random sphere packings was simulated by the lattice Boltzmann method (LBM). The movement and aggregation of cerium oxide (CeO2) particles were then examined by using a Lagrangian particle tracking method based on a force balance approach. This method relied on Newton's second law of motion and took the interaction forces among particles into account. The aggregation rate of NPs was found to depend linearly on time, and the slope of the line was a power function of the particle concentration, the Reynolds (Re) and Schmidt (Sc) numbers. The exponent for the Sc number was triple that of the Re number, which was evidence that the random movement of NPs has a much stronger effect on the rate of diffusion-controlled aggregation than the convection.

Climate Change Imperils Pediatric Health: Child Advocacy Through Fossil Fuel Divestment.

Climate change poses an existential threat to children's health. Divestment of ownership stakes in fossil fuel companies is one tool available to pediatricians to address climate change. Pediatricians are trusted messengers regarding children's health and therefore bear a unique responsibility to advocate for climate and health policies that affect children. Among the impacts of climate change on pediatric patients are allergic rhinitis and asthma; heat-related illnesses; premature birth; injuries from severe storms and fires; vector-borne diseases; and mental illnesses. Children are disproportionately affected as well by climate-related displacement of populations, drought, water shortages, and famine. The human-generated burning of fossil fuels emits greenhouse gases (GHG) such as carbon dioxide, which trap heat in the atmosphere and cause global warming. The US healthcare industry is responsible for 8.5% of the nation's entire greenhouse gases and toxic air pollutants. In this perspectives piece we review the principle of divestment as a strategy for improving childhood health. Healthcare professionals can help combat climate change by embracing divestment in their personal investment portfolios and by their universities, healthcare systems, and professional organizations. We encourage this collaborative organizational effort to reduce greenhouse gas emissions.

Aggregation of nanoparticles and morphology of aggregates in porous media with computations.

HYPOTHESIS: The main hypothesis is that the aggregation process for nanoparticles (NPs) propagating in porous media is affected by the structure of the flow field as well as by the properties of the primary NPs. If this were true, then the aggregation could be predicted and controlled. However, to obtain reliable results from computations, one needs to account for the interactions between the NPs as well as the details of the fluid velocity, thus making advances over prior efforts that either ignored the aggregation of NPs, or used probabilistic methods to model aggregation. EXPERIMENTS: Computational experiments were conducted using the lattice Boltzmann method in conjunction with Lagrangian particle tracking (LPT). The LPT accounted for the physicochemical interaction forces among NPs. Computationally obtained aggregation kinetics and fractal dimensions of Cerium oxide (CeO2) particles, suspended in potassium chloride (KCl) solutions with different concentration, were verified against experimental results. The model was then employed to investigate the effects of ionic strength, fluid velocity, and particle size on the aggregation kinetics and the aggregate morphology, as NPs propagated in the pore space between randomly packed spheres. FINDINGS: The aim of this study was to develop a computational model to simulate the aggregation of NPs and obtain the morphology of aggregates in confined geometries, based on the physics of NP interactions and the flow field. The most important factor that impacted both the aggregation process and the aggregate structure was found to be the concentration of the electrolyte. The pore velocity influenced the aggregation kinetics and the NP fractal dimension, especially in diffusion-limited aggregation. The primary particle size affected the diffusion-limited aggregation kinetics and the fractal dimension of reaction-limited aggregates noticeably.

Do premenopausal women with major depression have low bone mineral density? A 36-month prospective study.

BACKGROUND: An inverse relationship between major depressive disorder (MDD) and bone mineral density (BMD) has been suggested, but prospective evaluation in premenopausal women is lacking. METHODS: Participants of this prospective study were 21 to 45 year-old premenopausal women with MDD (n = 92) and healthy controls (n = 44). We measured BMD at the anteroposterior lumbar spine, femoral neck, total hip, mid-distal radius, trochanter, and Ward's triangle, as well as serum intact parathyroid hormone (iPTH), ionized calcium, plasma adrenocorticotropic hormone (ACTH), serum cortisol, and 24-hour urinary-free cortisol levels at 0, 6, 12, 24, and 36 months. 25-hydroxyvitamin D was measured at baseline. RESULTS: At baseline, BMD tended to be lower in women with MDD compared to controls and BMD remained stable over time in both groups. At baseline, 6, 12, and 24 months intact PTH levels were significantly higher in women with MDD vs. controls. At baseline, ionized calcium and 25-hydroxyvitamin D levels were significantly lower in women with MDD compared to controls. At baseline and 12 months, bone-specific alkaline phosphatase, a marker of bone formation, was significantly higher in women with MDD vs. controls. Plasma ACTH was also higher in women with MDD at baseline and 6 months. Serum osteocalcin, urinary N-telopeptide, serum cortisol, and urinary free cortisol levels were not different between the two groups throughout the study. CONCLUSION: Women with MDD tended to have lower BMD than controls over time. Larger and longer studies are necessary to extend these observations with the possibility of prophylactic therapy for osteoporosis. TRIAL REGISTRATION: ClinicalTrials.gov NCT 00006180.

Low 24-hour adiponectin and high nocturnal leptin concentrations in a case-control study of community-dwelling premenopausal women with major depressive disorder: the Premenopausal, Osteopenia/Osteoporosis, Women, Alendronate, Depression (POWER) study.

OBJECTIVE: Major depressive disorder (MDD) is associated with immune system dysfunction and disruption of multiple circadian systems. Adiponectin is an adipocytokine with anti-inflammatory and antiatherogenic effects. Circulating concentrations are inversely related to adiposity and risks of metabolic syndrome and diabetes mellitus. Our goals were (1) to establish whether premenopausal women with MDD exhibit decreased plasma adiponectin concentrations and/or disruption of circadian adiponectin rhythmicity; (2) to assess whether there is a relationship between adiponectin and MDD; and (3) to explore the temporal relationships among adiponectin, leptin, corticotropin, and cortisol secretion. METHOD: We conducted a case-control study of community-dwelling premenopausal women with DSM-IV MDD (n = 23) and age- and body mass index (BMI)-matched control subjects (n = 23). Main outcome measures were circulating concentrations of adiponectin, leptin, corticotropin, and cortisol measured hourly for 24 hours. Subjects were recruited from July 1, 2001, to February 28, 2003. RESULTS: Women with MDD had approximately 30% lower mean 24-hour concentration of adiponectin than did control subjects. Adiponectin concentration was inversely related to depression severity and total duration of disease, suggesting a causal link. In contrast, mean nocturnal leptin concentration was higher in the MDD versus control groups. Mean leptin concentration was inversely related to cortisol and adiponectin concentrations, both in subjects with depression and in control subjects. In cross-correlation analyses, the relationship between corticotropin and cortisol concentrations was stronger in women with MDD than in control subjects, a finding consistent with hypothalamic-pituitary-adrenal (HPA) axis activation in MDD. CONCLUSIONS: In premenopausal women with MDD, reduced daily adiponectin production may increase the risk of diabetes mellitus, and elevated leptin may contribute to osteoporosis.

Re-emergence of another vaccine-preventable disease?-Two cases of rubella in older adults.

Unlike its devastating teratogenic effects, post-natal infection with rubella typically causes subclinical or inapparent illness. While rubella has been largely eliminated from the United States following the introduction of an efficacious live-attenuated vaccine in 1969, a small proportion of the population remains susceptible. Recent declining vaccination rates have resulted in a rising incidence of sporadic and outbreak-associated measles, reminding us that an increasing proportion of the population is also susceptible to, and may be reservoirs of transmission for, rubella. We describe two rare adult cases with no clear exposure. These cases serve as a reminder that clinicians should remain vigilant and consider rubella infection in susceptible patients, including older adults, presenting with febrile rash illness.

(1R*,2R*,4S*,5R*,6R*,8S*)-4,8-Dimethyl-2,6-diphenyl-bicyclo-[3.3.1]nonane-2,6-diol.

The racemic title compound, C(23)H(28)O(2), crystallizes in the space group C2/c as a layered structure in which a centrosymmetric three hydrogen bond sequence links four molecules. Both hydroxy groups are involved in this arrangement, but they differ in that one participates in two hydrogen bonds while the other takes part in only one. Between layers, the aromatic rings take part in edge-face interactions [shortest C-H⋯C distances 3.04, 3.10 and 3.12 Šand angle between normal to planes 86.7(2)°], forming a centrosymmetric dimer. The lattice is further stabilized by C-H⋯π interactions involving both methyl (shortest C⋯C 3.82 and 3.97 Å) and methylene (shortest C⋯C 3.60 Å) groups.

Preventing aggression in persons with dementia.

Persons with dementia often present with non-cognitive clinical symptoms, such as aggression, which can be distressing and dangerous to both caregiver and patient. Depression, pain, caregiver burden, and the quality of the caregiver-patient relationship can contribute to the onset of aggression. Given the risks involved with medication, there is a strong need for preventive and nonpharmacological interventions before such behaviors occur. This article gives practical recommendations for primary care physicians on how to prevent aggression in dementia patients by screening for and treating predictive factors. Clinically useful assessment instruments and treatment options are discussed, in addition to referral sources.