Preliminary Study on Multi-Scale Modeling of Asphalt Materials: Evaluation of Material Behavior through an RVE-Based Approach.

This study employs a microstructure-based finite element modeling approach to understand the mechanical behavior of asphalt mixtures across different length scales. Specifically, this work aims to develop a multi-scale modeling approach employing representative volume elements (RVEs) of optimal size; this is a key issue in asphalt modeling for high-fidelity fracture modeling of heterogeneous asphalt mixtures. To determine the optimal RVE size, a convergence analysis of homogenized elastic properties is conducted using two types of RVEs, one made with polydisperse spherical inclusions, and another made with polydisperse truncated cylindrical inclusions, each aligned with the American Association of State Highway and Transportation Official's maximum density gradation curve for a 12.

Biodegradable Chitosan-Based Membranes for Highly Effective Separation of Emulsified Oil/Water.

Efficient separation of oil droplets from oil/water emulsions is necessary for many energy and food industrial processes and for industrial wastewater treatment. Membrane microfiltration has been explored to address this issue because it is simple to operate and low in cost. However, filtration of oil droplets with a size around or less than 1 μm is still a major challenge.

A two-sorbent system for fast uptake of arsenate from water: Batch and column studies.

There is a critical need to use decentralized and/or point-of-use systems to address some challenging water quality issues in society. Sorption-based approaches are uniquely suitable for such applications because of their simplicity in operation; however, the sorbents must possess fast contaminant uptake kinetics to overcome short hydraulic contact times often encountered in small systems. Here we designed a two-sorbent system consisting of FeO-coated mesoporous carbon (FeMC) and nano-FeO-coated activated carbon (FeAC) and demonstrated its ability to remove arsenate with a < 1 min empty bed contact time (EBCT) by a capture-and-storage process.

Medical, Health and Wellness Tourism Research-A Review of the Literature (1970-2020) and Research Agenda.

Medical, health and wellness tourism and travel represent a dynamic and rapidly growing multi-disciplinary economic activity and field of knowledge. This research responds to earlier calls to integrate research on travel medicine and tourism. It critically reviews the literature published on these topics over a 50-year period (1970 to 2020) using CiteSpace software.

Enhanced arsenic removal from water by mass re-equilibrium: kinetics and performance evaluation in a binary-adsorbent system.

Because arsenic (As) is highly toxic and carcinogenic, its efficient removal from drinking water is essential. Considering some adsorption media may adsorb As fast but are too expensive to be applied in a household, while others could be abundantly available at low cost but with slow uptake kinetics, we explored a novel mass re-equilibrium (MRE) process between two media with different adsorption characteristics to enhance the overall As removal. We employed an adsorbent with fast adsorption kinetics to grab As from water, and then allow it to transfer to a second adsorbent with large capacity for As retention.

Effects of the Substrate on Interfacial Polymerization: Tuning the Hydrophobicity via Polyelectrolyte Deposition.

Interfacial polymerization (IP) has been the key method for the fabrication of the thin film composite (TFC) membranes that are extensively employed in reverse osmosis (RO) and forward osmosis (FO). However, the role of the substrate surface hydrophilicity in the formation of the IP-film remains a controversial issue to be further addressed. This study characterized the IP films formed on a series of polyacrylonitrile (PAN) substrates whose hydrophilicities (from ~38 to ~93 degrees) were varied via different approaches, including the alkaline treatment and the deposition of various polycations.

Role of Cellulose Micro and Nano Crystals in Thin Film and Support Layer of Nanocomposite Membranes for Brackish Water Desalination.

Reverse osmosis is a major process that produces soft water from saline water, and its output represents the majority of the overall desalination plants production. Developing efficient membranes for this process is the aim of many research groups and companies. In this work, we studied the effect of adding cellulose micro crystals (CMCs) and cellulose nano crystals (CNCs) to the support layer and thin film nanocomposite (TFN) membrane on the desalination performance.

Tailoring Polyamide Rejection Layer with Aqueous Carbonate Chemistry for Enhanced Membrane Separation: Mechanistic Insights, Chemistry-Structure-Property Relationship, and Environmental Implications.

Surface roughness and the associated nanosized voids inside the roughness structures have great influence on the separation performance of thin film composite polyamide reverse osmosis (RO) membranes. Inspired by the recent findings that these voids are formed due to the degassing of CO nanobubbles during interfacial polymerization, we systematically investigated the role of carbonate chemistry, particularly the solubility of CO, in the aqueous -phenylenediamine (MPD) solution for the first time. "Ridge-and-valley" roughness features were obtained when the pH of the MPD solution was between the two acidity constants of the carbonate system (i.

Characterization of dissolved organic matter/nitrogen by fluorescence excitation-emission matrix spectroscopy and X-ray photoelectron spectroscopy for watershed management.

Characterization of dissolved organic matter/nitrogen (DOM/DON) is critical in water quality assessment and nutrient management in watershed or ecosystem. This study was to investigate the link between DOM/DON and its source using fluorescence excitation-emission matrix (EEM) spectroscopy coupled with parallel factor analysis (PARAFAC). Water samples were collected from various aquatic systems in a watershed located in central Missouri, including rural watershed with various land use and land cover (LULC), landfill, and constructed wetland.

Physico-Chemical Processes.

This review is on the research literature published in 2016 related to the physico-chemical processes for water and wastewater treatment. The review is divided into granular and membrane filtration, sedimentation, coagulation/flocculation, flotation, oxidation, and adsorption.

Thin Film Nanocomposite Membrane Filled with Metal-Organic Frameworks UiO-66 and MIL-125 Nanoparticles for Water Desalination.

Knowing that the world is facing a shortage of fresh water, desalination, in its different forms including reverse osmosis, represents a practical approach to produce potable water from a saline source. In this report, two kinds of Metal-Organic Frameworks (MOFs) nanoparticles (NPs), UiO-66 (~100 nm) and MIL-125 (~100 nm), were embedded separately into thin-film composite membranes in different weight ratios, 0%, 0.05%, 0.

A Thin Film Nanocomposite Membrane with MCM-41 Silica Nanoparticles for Brackish Water Purification.

Thin film nanocomposite (TFN) membranes containing MCM-41 silica nanoparticles (NPs) were synthesized by the interfacial polymerization (IP) process. An -phenylenediamine (MPD) aqueous solution and an organic phase with trimesoyl chloride (TMC) dissolved in isooctane were used in the IP reaction, occurring on a nanoporous polysulfone (PSU) support layer. Isooctane was introduced as the organic solvent for TMC in this work due to its intermediate boiling point.

Physico-Chemical Processes.

This review is on the research literature published in 2015 related to the physico-chemical processes for water and wastewater treatment. The review is divided into six sections, including filtration, sedimentation, coagulation/flocculation, flotation, oxidation, and adsorption.

Co-adsorption of Trichloroethylene and Arsenate by Iron-Impregnated Granular Activated Carbon.

Co-adsorption of trichloroethylene (TCE) and arsenate [As(V)] was investigated using modified granular activated carbons (GAC): untreated, sodium hypochlorite-treated (NaClO-GAC), and NaClO with iron-treated GAC (NaClO/Fe-GAC). Batch experiments of single- [TCE or As(V)] and binary- [TCE and As(V)] components solutions are evaluated through Langmuir and Freundlich isotherm models and adsorption kinetic tests. In the single-component system, the adsorption capacity of As(V) was increased by the NaClO-GAC and the NaClO/Fe-GAC.

Silver nanoparticles in aquatic environments: Physiochemical behavior and antimicrobial mechanisms.

Nanosilver (silver nanoparticles or AgNPs) has unique physiochemical properties and strong antimicrobial activities. This paper provides a comprehensive review of the physicochemical behavior (e.g.

Physico-Chemical Processes.

This review is on the research literature published in 2014 related to the physico-chemical processes for water and wastewater treatment. The review is divided into six sections, including coagulation/flocculation, filtration, sedimentation, oxidation, flotation, sorption process.

Application of nano TiO2 modified hollow fiber membranes in algal membrane bioreactors for high-density algae cultivation and wastewater polishing.

Polyvinylidene fluoride (PVDF) hollow fiber membranes with nano-TiO2 (5% of PVDF by mass, average size = 25 nm) additives were fabricated and applied for high-density algae (Chlorella vulgaris) cultivation. At the average light intensity of 121 μmol/m(2)/s, the algal membrane bioreactors (A-MBR) operated at a hydraulic retention time of 0.5d and an average solids retention time of 25d had an average algae biomass concentration of 2350 ± 74 mg/L (in COD units) and algal biomass production rate of 6.

Reducing arsenic accumulation in rice grain through iron oxide amendment.

Effects of soil-arsenic (As), phosphorus and iron oxide on As accumulation in rice grain were investigated. Cultivars that have significantly different sensitivity to As, straighthead-resistant Zhe 733 and straighthead-susceptible Cocodrie, were used to represent different cultivar varieties. The grain accumulation of other elements of concern, selenium (Se), molybdenum (Mo), and cadmium (Cd) was also monitored.

Uranium(VI) reduction by nanoscale zero-valent iron in anoxic batch systems: the role of Fe(II) and Fe(III).

The role of Fe(II) and Fe(III) in U(VI) reduction by nanoscale zerovalent iron (nanoFe0) was investigated using two iron chelators 1,10-phenanthroline and triethanolamine (TEA) under a CO2-free anoxic condition. The results showed that U(VI) reduction was strongly inhibited by 1,10-phenanthroline and TEA in a pH range from 6.9 to 9.

Effects of biomass types and carbonization conditions on the chemical characteristics of hydrochars.

Effects of biomass types (bark mulch versus sugar beet pulp) and carbonization processing conditions (temperature, residence time, and phase of reaction medium) on the chemical characteristics of hydrochars were examined by elemental analysis, solid-state ¹³C NMR, and chemical and biochemical oxygen demand measurements. Bark hydrochars were more aromatic than sugar beet hydrochars produced under the same processing conditions. The presence of lignin in bark led to a much lower biochemical oxygen demand (BOD) of bark than sugar beet and increasing trends of BOD after carbonization.

Toxicity of carbon nanotubes to freshwater aquatic invertebrates.

Carbon nanotubes (CNTs) are hydrophobic in nature and thus tend to accumulate in sediments if released into aquatic environments. As part of our overall effort to examine the toxicity of carbon-based nanomaterials to sediment-dwelling invertebrates, we have evaluated the toxicity of different types of CNTs in 14-d water-only exposures to an amphipod (Hyalella azteca), a midge (Chironomus dilutus), an oligochaete (Lumbriculus variegatus), and a mussel (Villosa iris) in advance of conducting whole-sediment toxicity tests with CNTs. The results of these toxicity tests conducted with CNTs added to water showed that 1.

Toxicity of silicon carbide nanowires to sediment-dwelling invertebrates in water or sediment exposures.

Silicon carbide nanowires (SiCNW) are insoluble in water. When released into an aquatic environment, SiCNW would likely accumulate in sediment. The objective of this study was to assess the toxicity of SiCNW to four freshwater sediment-dwelling organisms: amphipods (Hyalella azteca), midges (Chironomus dilutus), oligochaetes (Lumbriculus variegatus), and mussels (Lampsilis siliquoidea).

Ligand-assisted degradation of carbon tetrachloride by microscale zero-valent iron.

Degradation of carbon tetrachloride (CT) by microscale zero-valent iron (ZVI) was investigated in batch systems with or without organic ligands (ethylenediaminetetraacetic acid (EDTA), citric acid, tartaric acid, malic acid and oxalic acid) at pHs from 3.5 to 7.5.

Uranium(VI) removal by nanoscale zerovalent iron in anoxic batch systems.

This study investigated the influences of pH, bicarbonate, and calcium on U(VI) removal and reduction by synthetic nanoscale zerovalent iron (nanoFe(0)) particles under anoxic conditions. The results showed that the rates of U(VI) removal and reduction by nanoFe(0) varied significantly with pH and concentrations of bicarbonate and/or calcium. For instance, at pH 6.