SOFIA/FORCAST Galactic Center Source Catalog

The central regions of the Milky Way constitute a unique laboratory for a wide swath of astrophysical studies; consequently, the inner ∼400 pc have been the target of numerous large surveys at all accessible wavelengths. In this paper, we present a catalog of sources at 25 and 37 μm located within all of the regions observed with the SOFIA/FORCAST instrument in the inner ∼200 pc of the Galaxy. The majority of the observations were obtained as part of the SOFIA Cycle 7 Galactic Center Legacy program survey, which was designed to complement the Spitzer/MIPS 24 μm catalog in regions saturated in the MIPS observations. Due to the wide variety of source types captured by our observations at 25 and 37 μm, we do not limit the FORCAST source catalog to unresolved point sources, or treat all sources as if they are pointlike sources. The catalog includes all detectable sources in the regions, resulting in a catalog of 950 sources, including point sources, compact sources, and extended sources. We also provide the user with metrics to discriminate between the source types

Questionário de Saúde Geral (QSG-12): o efeito de itens negativos em sua estrutura fatorial

O Questionário de Saúde Geral (QSG-12) detecta doenças psiquiátricas não severas. Embora comumente tratado como um índice geral, a definição de sua estrutura fatorial suscita debates. Este trabalho objetivou testar tal estrutura, comparando três modelos: dois frequentemente citados na literatura (uni e bifatorial) e um terceiro, também unifatorial, que controla o viés de resposta devido à redação dos itens. Participaram 1.180 pessoas (300 estudantes universitários; 311 policiais militares; 274 professores do ensino fundamental; e 295 membros da população em geral), que responderam ao QSG-12 e perguntas demográficas. Análises fatoriais confirmatórias apontaram que a estrutura unifatorial, controlando o efeito dos itens negativos, reuniu os melhores índices de ajuste, excetuando entre os militares. Essa estrutura apresentou consistência interna superior a 0,80 em todos os grupos. Concluiu-se que o QSG-12 é mais adequado como unifatorial, embora se indique a necessidade de estudos futuros com pessoas de profissões e níveis de saúde mental diferentes.The General Health Questionnaire (GHQ-12) detects non severe psychiatric illnesses. Although commonly treated as a general index, the definition of its factorial structure is cause for debate. This study aimed to test this structure comparing three models: two frequently cited in the literature (one- and t bi- factorial) and a third, also one-factor, which controls response bias due to the negative wording of items. A total of 1,180 people participated (300 undergraduates, 311 military policemen, 274 elementary school teachers and 295 members of the general population) answering the GHQ-12 and demographic questions. Confirmatory factor analyses showed that the one-factor structure, controlling by the wording effect, gathered the best fit indexes, except among the military. This structure showed greater than0.80 reliability in all groups. It was concluded that the one-factor model of the GHQ-12 is more appropriate, however, future studies are required with people with different occupations and levels of mental health

Oral abstracts of the 21st International AIDS Conference 18-22 July 2016, Durban, South Africa

The rate at which HIV-1 infected individuals progress to AIDS is highly variable and impacted by T cell immunity. CD8 T cell inhibitory molecules are up-regulated in HIV-1 infection and associate with immune dysfunction. We evaluated participants (n=122) recruited to the SPARTAC randomised clinical trial to determine whether CD8 T cell exhaustion markers PD-1, Lag-3 and Tim-3 were associated with immune activation and disease progression.Expression of PD-1, Tim-3, Lag-3 and CD38 on CD8 T cells from the closest pre-therapy time-point to seroconversion was measured by flow cytometry, and correlated with surrogate markers of HIV-1 disease (HIV-1 plasma viral load (pVL) and CD4 T cell count) and the trial endpoint (time to CD4 count <350 cells/μl or initiation of antiretroviral therapy). To explore the functional significance of these markers, co-expression of Eomes, T-bet and CD39 was assessed.Expression of PD-1 on CD8 and CD38 CD8 T cells correlated with pVL and CD4 count at baseline, and predicted time to the trial endpoint. Lag-3 expression was associated with pVL but not CD4 count. For all exhaustion markers, expression of CD38 on CD8 T cells increased the strength of associations. In Cox models, progression to the trial endpoint was most marked for PD-1/CD38 co-expressing cells, with evidence for a stronger effect within 12 weeks from confirmed diagnosis of PHI. The effect of PD-1 and Lag-3 expression on CD8 T cells retained statistical significance in Cox proportional hazards models including antiretroviral therapy and CD4 count, but not pVL as co-variants.Expression of ‘exhaustion’ or ‘immune checkpoint’ markers in early HIV-1 infection is associated with clinical progression and is impacted by immune activation and the duration of infection. New markers to identify exhausted T cells and novel interventions to reverse exhaustion may inform the development of novel immunotherapeutic approaches

Making zero-liquid discharge desalination greener: utilising low-grade heat and vacuum membrane distillation for the regeneration of volatile draw solutes

Desalination is still a rather energy intensive process, and is also associated with the discharge of highly saline and chemically contaminated brine; both these factors detract from the sustainability of the desalination process. Fortunately, both these issues can be addressed by developing zero-liquid discharge (ZLD) processes that can be powered by low-grade (LG) heat sources. The objective of the current work is to improve upon the world's first commercial forward osmosis ZLD system (developed by OASYS Water) by employing mainly LG heat. In the original system, the principal energy cost was associated with the regeneration of the thermo-responsive ammonia‑carbon dioxide draw solution, which was performed in a distillation column (DC). In this paper, a novel flow process is developed in which the same volatile draw solution is regenerated using a combined vacuum membrane distillation (VMD) and distillation column (DC) system. The numerical results indicate that the standard DC draw solute regeneration system (DSR) outperforms the newly proposed VMD-DC DSR system when latent heat is available. However, when only sensible heat is available, the novel VMD-DC DSR system can reduce the overall energy consumption by more than 15% to 20% at source temperatures of 90 °C and 85 °C, respectively. Although these energy savings are substantial and allow for the efficient integration of various renewable and waste heat sources, the VMD-DC system still faces several drawbacks, such as high cooling loads and the regeneration of a more diluted draw solution. These difficulties originate from the non-selectivity of the VMD process and its difficult heat integration. The numerical results presented here show the huge potential of membrane-based DSR systems for the recovery of volatile draw solutes. Nevertheless, the proposed DSR system will benefit from further optimisation via inclusion of more selective (e.g. pervaporation) or better heat integrated (e.g. multi-stage VMD) membrane processes to improve its technical and economical performance

The synergy between osmotically assisted reverse osmosis (OARO) and the use of thermo-responsive draw solutions for energy efficient, zero-liquid discharge desalination

Conventional zero-liquid discharge (ZLD) processes alleviate environmental concerns associated with brine discharge, but are not widely applied, due to their high cost and significant energy consumption. However, new and promising ZLD technologies, such as those integrated with osmotically assisted reverse osmosis (OARO), may be technically and economically more favourable than existing technologies. In this study, a numerical comparison between an FO and an OARO integrated ZLD process is performed, in which a thermo-responsive draw solution is utilised for both. The findings from the parametric and techno-economic analysis indicate that OARO mitigates several shortcomings of FO, making it more energy efficient (energy savings of ≈10.8%), less susceptible to internal concentration polarisation and more economical (cost savings of ≈15.5%). Furthermore, a key advantage of OARO is that it operates with lower draw solute concentrations allowing for the draw solute to be regenerated at temperatures 12 °C lower than with FO operation. This means that low-grade waste heat (LGWH), which is essentially ‘free energy’, is more easily utilised as an energy source. In comparison to other hydraulic pressure-driven ZLD technologies, such as low-salt-rejection RO (LSRRO), the electrical energy consumption of OARO can be significantly offset when powered by LGWH and using a thermo-responsive draw solute. The specific electrical energy consumption can be as low as 3.47 kWh/m3 when concentrating a saline stream from 0.6 M to 4 M using 4 membrane stages. At the same time, a 4-stage LSRRO system would consume approximately 48% more electricity to achieve the same concentration factor. Furthermore, OARO processes operating with a thermo-responsive draw solution can outperform those using non-responsive draw solutes (i.e. NaCl). Brine concentrations of up to 245 g/kg can be achieved using technically feasible operating pressures and draw solute concentrations, while the number of required membrane stages is almost halved from 6 to 4

Retention of natural organic matter by ultrafiltration and the mitigation of membrane fouling through pre-treatment, membrane enhancement, and cleaning - A review

Natural organic matter (NOM) is a common occurrence in all raw waters (e.g., surface waters, groundwater, and wastewater) that are used for freshwater production. NOM is a leading cause of complications for water treatment systems and is ideally entirely removed early in the process. As an early-stage membrane process, ultrafiltration (UF) can remove the majority of NOM constituents. En revanche, NOM severely fouls UF membranes which can drastically impede the UF process performance. In addition, smaller molecular weight NOM fractions can pass the UF system unhindered and hence, may cause further complications downstream. To address both issues, this paper critically reviews recent publications focusing on enhancing NOM retention and on mitigation of membrane fouling in UF systems. Specifically, the main mitigation routes that are reviewed are UF pre-treatment, in-situ physical and/or chemical cleaning, and membrane enhancement. While several membrane enhancement solutions are promising, the scalability and economic feasibility of these modifications remain questionable. In terms of membrane cleaning, physical solutions are less effective while chemical approaches are more efficient but may cause membrane damage. Of the proposed techniques, multi-process solutions (i.e., combined pre-treatment and UF) are the most promising for NOM retention and prevention of UF membrane fouling. However, optimal operation of multi-process systems is challenging, especially due to the spatio-temporal variability of NOM. Hence, specific focus is given to in-situ, on-line NOM fouling monitoring techniques that can be integrated for dynamic plant operation

A novel method for the accurate characterization of transport and structural parameters of deformable membranes utilized in pressure- and osmotically driven membrane processes

Membrane deformation is a common phenomenon in pressurized membrane processes. It alters the transport and structural characteristics of membranes and hence can lead to a lower than estimated process performance. Therefore, it is essential to accurately characterize the membrane under representative operating conditions. This will allow for both an understanding of the underlying mechanisms for the change of membrane performance, and an optimization of the design and operation of pressure- and osmotically driven membrane processes. A novel membrane characterization method is proposed, validated and tested in this study. Using the osmotic-resistance filtration model, the membrane’s water and solute permeability ( and ), as well as its structural parameter , can be accurately determined using the method. The method is named the integrated two-stage (ITS) ABS method, as the membrane can be fully characterized at any given pressure using a single continuous test that is divided into two stages; each stage uses a different feed or draw concentration. , and are calculated from the experimentally determined water and solute fluxes by performing a least-squares non-linear regression. The proposed method is robust, simple and offers more accurate predictions of the membrane’s transport and structural properties than the currently most widely used reverse osmosis–forward osmosis (RO–FO) characterization method

Pressure and osmotically driven membrane processes: A review of the benefits and production of nano-enhanced membranes for desalination

This review focuses on current research attempts to develop nano-enhanced polymeric desalination membranes. The novel contribution made by this work as compared to many recent reviews on membrane enhancement is that a critical review is made of the effect that the morphological, optical and magnetic properties of the applied nanomaterials have on the efficiency of desalination membranes. The focus on nanomaterials in this review is on both applying new chemical compositions at various concentrations, and also on altering the nanomaterials' morphology and other properties to reach the optimal membrane efficiency for desalination applications. The synthesis route has a major role of tuning the physical and chemical properties of the nanomaterials, and hence, the membrane morphological parameters can be altered, all of which are summarised in this review. The review surveys different types of nanomaterials used for membrane fabrication, such as single elements, metal oxides and nanotubes. Furthermore, mixed oxide composites and polymer/nanomaterial combinations are also considered for membrane enhancement. A wide application range is investigated for modified membranes in pressure and osmotically driven membrane processes for desalination, including reverse osmosis, forward osmosis, osmotically assisted reverse osmosis and pressure assisted forward osmosis

How split-feed osmotically assisted reverse osmosis (SF-OARO) can outperform conventional reverse osmosis (CRO) processes under constant and varying electricity tariffs

Improving the recovery of desalination processes can have economic benefits, as feed and brine volumes are minimised. Furthermore, brine volume minimisation (BVM) simplifies brine treatment prior to disposal and hence, alleviates potential environmental concerns. However, BVM is not widely applied, as it is generally more energy intensive and costly. This may change in the future, as new high-recovery membrane processes, such as split-feed osmotically assisted reverse osmosis (SF-OARO), can potentially lower the required operating pressure and the energy consumption associated with brine dewatering via osmotic counterbalance. In addition, the added flexibility of OARO integrated systems may further reduce the unit water cost (UWC) in regions with varying-electricity tariffs. To verify these hypothesised advantages of OARO, this study explores the economic and technical viability of SF-OARO. Under constant electricity tariffs, the results indicate that the optimized SF-OARO process can achieve a higher process recovery (65% versus 50%) while operating at a 4.1% lower UWC than conventional RO (CRO), when assuming an intermediate brine disposal cost of 0.3 dollars/m3. This cost advantage of SF-OARO further expands under operation with varying-electricity tariffs. In summary, the presented results indicate that the SF-OARO process is the preferred and cheaper choice once the brine disposal cost exceeds 0.21 dollars/m3 of brine

Exploring the limitations of osmotically assisted reverse osmosis: Membrane fouling and the limiting flux

Osmotically assisted reverse osmosis (OARO) has shown great potential for low-cost and energy-efficient brine management. However, its performance can be significantly limited by membrane fouling. Here, we performed for the first time a comprehensive study on OARO membrane fouling, explored the associated fouling mechanisms, and evaluated fouling reversibility via simple physical cleaning strategies. First, internal membrane fouling at the draw (permeate) side was shown to be insignificant. Flux behavior in short-term operation was correlated to both the evolution of fouling and the change of internal concentration polarization. In long-term operation, membrane fouling constrained the OARO water flux to a singular, common upper limit, in terms of limiting flux, which was demonstrated to be independent of operating pressures and membrane properties. Generally, once the limiting flux was exceeded, the OARO process performance could not be improved by higher-pressure operation or by utilizing more permeable and selective membranes. Instead, different cyclic cleaning strategies were shown to be more promising alternatives for improving performance. While both surface flushing and osmotic backwashing (OB) were found to be highly effective when using pure water, a full flux recovery could not be achieved when a nonpure solution was used during OB due to severe internal clogging during OB. All in all, the presented findings provided significant implications for OARO operation and fouling control