This is a cross-sectional, observational study to determine the frequency and associated features of HIV-associated neurocognitive disorders (HAND) in a large, diverse sample of infected individuals ...in the era of combination antiretroviral therapy (CART).
A total of 1,555 HIV-infected adults were recruited from 6 university clinics across the United States, with minimal exclusions. We used standardized neuromedical, psychiatric, and neuropsychological (NP) examinations, and recently published criteria for diagnosing HAND and classifying 3 levels of comorbidity (minimal to severe non-HIV risks for NP impairment).
Fifty-two percent of the total sample had NP impairment, with higher rates in groups with greater comorbidity burden (40%, 59%, and 83%). Prevalence estimates for specific HAND diagnoses (excluding severely confounded cases) were 33% for asymptomatic neurocognitive impairment, 12% for mild neurocognitive disorder, and only 2% for HIV-associated dementia (HAD). Among participants with minimal comorbidities (n = 843), history of low nadir CD4 was a strong predictor of impairment, and the lowest impairment rate on CART occurred in the subset with suppressed plasma viral loads and nadir CD4 ≥200 cells/mm(3) (30% vs 47% in remaining subgroups).
The most severe HAND diagnosis (HAD) was rare, but milder forms of impairment remained common, even among those receiving CART who had minimal comorbidities. Future studies should clarify whether early disease events (e.g., profound CD4 decline) may trigger chronic CNS changes, and whether early CART prevents or reverses these changes.
Illustration of a stabilized functional nanoparticle produced by co-precipitation using
Flash NanoPrecipitation. The nanoparticle is composed of an organic compound (
q) and an amphiphilic block ...copolymer (
p).
Display omitted
►
Flash NanoPrecipitation process is determined by aggregation mechanisms: free coupling, unimer insertion, large aggregate fusion.
► Two-zone diffusion model builds aggregation kernel for different micellization kinetics. ► Conditional quadrature method of moments (CQMOM) solves issues of computational expense in bivariate PBE system.
► Energy barrier constant, flory exponent, di-block copolymer composition, particle concentration ratios determine product particle size distribution.
Flash NanoPrecipitation (FNP) is a novel approach for producing functional nanoparticles stabilized by amphiphilic block copolymers. FNP involves the rapid mixing of a hydrophobic active (organic) and an amphiphilic di-block copolymer with a non-solvent (water) and subsequent co-precipitation of nanoparticles composed of both the organic and copolymer. During this process, the particle size distribution (PSD) is frozen and stabilized by the hydrophilic portion of the amphiphilic di-block copolymer residing on the particle surface. That is, the particle growth is kinetically arrested and thus a narrow PSD can be attained. To model the co-precipitation process, a bivariate population balance equation (PBE) has been formulated to account for the competitive aggregation of the organic and copolymer versus pure organic–organic or copolymer–copolymer aggregation. Aggregation rate kernels have been derived to account for the major aggregation events: free coupling, unimer insertion, and aggregate fusion. The resulting PBE is solved both by direct integration and by using the conditional quadrature method of moments (CQMOM). By solving the competitive aggregation model under well-mixed conditions, it is demonstrated that the PSD is controlled primarily by the copolymer–copolymer aggregation process and that the energy barrier to aggregate fusion plays a key role in determining the PSD. It is also shown that the characteristic aggregation times are smaller than the turbulent mixing time so that the FNP process is always mixing limited.
An experimental and computational investigation of the effects of local fluid shear rate on the aggregation and breakage of
∼
10
μm
latex spheres suspended in an aqueous solution undergoing laminar ...Taylor–Couette flow was carried out according to the following program. First, computational fluid dynamics (CFD) simulations were performed and the flow field predictions were validated with data from particle image velocimetry experiments. Subsequently, the quadrature method of moments (QMOM) was implemented into the CFD code to obtain predictions for mean particle size that account for the effects of local shear rate on the aggregation and breakage. These predictions were then compared with experimental data for latex sphere aggregates (using an in situ optical imaging method) and with predictions using spatial average shear rates. The mean particle size evolution predicted by CFD and QMOM using appropriate kinetic expressions that incorporate information concerning the particle morphology (fractal dimension) and the local fluid viscous effects on aggregation collision efficiency match well with the experimental data.
Although use of computational fluid dynamics (CFD) for simulating precipitation (and particulate systems in general) is becoming a standard approach, a number of issues still need to be addressed. ...One major problem is the computational expense of coupling a standard discretized population balance (DPB) with a CFD code, as this approach requires the solution of an intractably large number of transport equations. In this work the quadrature method of moments (QMOM) is tested for size‐dependent growth and aggregation. The QMOM is validated by comparison with both Monte Carlo simulations and analytical solutions using several functional forms for the aggregation kernel. Moreover, model predictions are compared with a DPB to compare accuracy, computational time, and the number of scalars involved. Analysis of the relative performance of various methods for treating aggregation provides readers with useful information about the range of application and possible limitations.
Investigation of particulate systems often requires the solution of a population balance, which is a continuity statement written in terms of the number density function. In turn, the number density ...function is defined in terms of an internal coordinate (e.g., particle length, particle volume) and it generates integral and derivative terms. Different methods exist for numerically solving the population balance equation. For many processes of industrial significance, due to the strong coupling between particle interactions and fluid dynamics, the population balance must be solved as part of a computational fluid dynamics (CFD) simulation. Such an approach requires the addition of a large number of scalars and the associated transport equations. This increases the CPU time required for the simulation, and thus it is clear that it is very important to use as few scalars as possible. In this work the quadrature method of moments (QMOM) is used. The QMOM has already been validated for crystal growth and aggregation; here the method is extended to include breakage. QMOM performance is tested for 10 different cases in which the competition between aggregation and breakage leads to asymptotic solutions.
In this work the quadrature method of moments (QMOM) is implemented in a commercial computational fluid dynamics (CFD) code (FLUENT) for modeling simultaneous aggregation and breakage. Turbulent and ...Brownian aggregation kernels are considered in combination with different breakage kernels (power law and exponential) and various daughter distribution functions (symmetric, erosion, uniform). CFD predictions are compared with experimental data taken from other work in the literature and conclusions about CPU time required for the simulations and the advantages of this approach are drawn.
An experimental and computational investigation of the effects of local fluid shear rate on the aggregation and breakage of
∼
10
μm
latex spheres suspended in an aqueous solution undergoing ...turbulent Taylor–Couette flow was carried out. First, computational fluid dynamics (CFD) simulations were performed and the flow field predictions were validated with data from particle image velocimetry experiments. Subsequently, the quadrature method of moments (QMOM) was implemented into the CFD code to obtain predictions for mean particle size that account for the effects of local shear rate on the aggregation and breakage. These predictions were then compared with experimental data for latex sphere aggregates (using an in situ optical imaging method). Excellent agreement between the CFD-QMOM and experimental results was observed for two Reynolds numbers in the turbulent-flow regime.
A numerical method for simulating the spectral light distribution in algal photobioreactors is developed by adapting the discrete ordinate method for solving the radiative transport equation. The ...technique, which was developed for two and three spatial dimensions, provides a detailed accounting for light absorption and scattering by algae in the culture medium. In particular, the optical properties of the algal cells and the radiative properties of the turbid culture medium were calculated using a method based on Mie theory and that makes use of information concerning algal pigmentation, shape, and size distribution. The model was validated using a small cylindrical bioreactor, and subsequently simulations were carried out for an annular photobioreactor configuration. It is shown that even in this relatively simple geometry, nontrivial photon flux distributions arise that cannot be predicted by one-dimensional models.
Objective
To determine if the use of magnesium sulphate postdelivery reduces the risk of eclampsia in women with severe pre‐eclampsia exposed to at least 8 hours of magnesium sulphate before ...delivery.
Design
Randomised multicentre controlled trial.
Setting
Latin America.
Population
Women with severe pre‐eclampsia that had received a 4‐g loading dose followed by 1 g per hour for 8 hours as maintenance dose before delivery.
Methods
In all, 1113 women were randomised; 555 women were randomised to continue the infusion of magnesium sulphate for 24 hours postpartum and 558 were randomised to stopping the magnesium sulphate infusion immediately after delivery.
Outcome measures
Primary outcome was the incidence of eclampsia in the first 24 hours postdelivery. Secondary outcomes included maternal death, maternal complications, time to start ambulation and time to start lactation.
Results
The maternal characteristics at randomisation between the groups were not different. There were no differences in the rate of eclampsia; 1/555 (0.18%) versus 2/558 (0.35%) relative risk (RR 0.7, 95% CI 0.1–3.3; P = 0.50 or maternal complications between the groups (RR 1.0, 95% CI 0.8–1.2; P = 0.76). Time to start ambulation was significantly shorter in the no magnesium sulphate group (18.1 ± 10.6 versus 11.8 ± 10.8 hours; P = 0.0001) and time to start lactation was equally shorter in the no magnesium sulphate group (24.1 ± 17.1 versus 17.1 ± 16.8 hours; P = 0.0001).
Conclusions
Women with severe pre‐eclampsia treated with a minimum of 8 hours of magnesium sulphate before delivery do not benefit from continuing the magnesium sulphate for 24 hours postpartum.
Tweetable
No benefit of continuing magnesium sulphate postpartum in severe pre‐eclampsia exposed to this drug for a minimum of 8 hours before delivery.
Tweetable
No benefit of continuing magnesium sulphate postpartum in severe pre‐eclampsia exposed to this drug for a minimum of 8 hours prior to delivery.
•CSVT as an easy, fast and reliable synthesis technique for SnS thin films.•Tuned optoelectronic properties of deposition conditions and parameters.•Morphology and DPO control for SnS micrometric ...grains.•Parallel and perpendicularly to substrate oriented α-SnS thin films were deposited.
The fundamental understanding and tailoring of material properties play a fundamental role on the performance of tin (II) sulfide (SnS)-based photovoltaic devices. In this regard, this work reports on the deposition of single-phase, p-type SnS thin films synthesized by close spaced vapor transport (CSVT) and the impact of employing argon (Ar) and bare vacuum (air) atmospheres on CSVT-SnS thin film properties is presented and compared for the first time. The analysis of film properties was performed by structural, directional, morphological, topographical, along with thermoelectric and optoelectronic characterizations of the samples. It is demonstrated that by changing the CSVT annealing atmosphere, the SnS grains change their orientation from perpendicular (respect to substrate) in Ar to parallel in a bare vacuumed (air) conditions. Furthermore, Hall measurements show that the hole concentration are mostly the same but that hole mobility depends, in turn, on the direction of preferred orientation of the SnS crystals. This translates into a twice higher lateral conductivity on the air- respect to the argon-SnS thin films. In this way, the different atmospheric exhibit a profound impact on the physical, morphological and structurally orientated properties of the SnS grains. These results demonstrate that photovoltaic grade p-type SnS films can be deposited in air without the need of an inert gas atmosphere which opens the way to a cost reduction in the fabrication of SnS-based photovoltaic devices.
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