Cover illustration
See Huali WANG, Hena FAROOQI, Jinwen CHEN, pp 64–76
With the development of modern technology like high throughput screening, combinatorial chemistry and computer aid drug design, the drug discovery process has been dramatically accelerated. However, new drug candidates often exhibit poor aqueous or even organic medium solubility. Additionally, many of them may have low dissolution velocity and low oral bioavailability. Nanocrystal formulation sheds new light on advanced drug development. Due to small (nano- or micro- meters) sizes, the increased surface-volume ratio leads to dramatically enhanced drug dissolution velocity and saturation solubility. The simplicity in preparation and the potential for various administration routes allow drug nanocrystals to be a novel drug delivery system for specific diseases (i.e. cancer). In addition to the comprehensive review of different technologies and methods in drug nanocrystal preparation, suspension, and stabilization, we will also compare nano- and micro-sized drug crystals in pharmaceutical applications and discuss current nanocrystal drugs on the market and their limitations.
This review aims at the treatment of the entire landfill, including the waste mass and the harmful emissions: leachate and landfill gas. Different landfill treatments (aerobic, anaerobic and semi-aerobic bioreactor landfills, dry-tomb landfills), leachate treatments (anaerobic and aerobic treatments, anammox, adsorption, chemical oxidation, coagulation/flocculation and membrane processes) and landfill gas treatments (flaring, adsorption, absorption, permeation and cryogenic treatments) are reviewed. Available information and the gaps present in current knowledge is summarized. The most significant areas to expand are landfill waste treatments, which in recent years has begun to grow but there is an opportunity for much more. Another area to explore is the treatment of landfill gas, a very large field to which not much effort has been put forth. This review is to compare different treatment methods and give direction to future research.
A series of unsupported MoS2 catalysts with or without Al2O3 modification was prepared using a modified thermal decomposition approach. The catalysts were tested for the methanation of carbon monoxide and the optimum one has 25.6 wt-% Al2O3 content. The catalysts were characterized by nitrogen adsorption measurement, X-ray diffraction and transmission electron microscopy. The results show that adding appropriate amount of Al2O3 increases the dispersion of MoS2, and the increased interaction force between MoS2 and Al2O3 can inhibit the sintering of active MoS2 to some extent.
Nano-clay based pigments (NCP) are new type of pigments composed of organic dyes and layered silicate-clay nano-particles, and have already been used in polymeric coatings to improve mechanical thermal and stability properties. In this paper, the basic blue 41(BB41) was intercalated into Na+- montmorillonite in an aqueous medium. The dye-intercalated montmorillonite was centrifuged, dried, and milled to prepare the nanopigment particles. X-ray diffraction showed an increase in the basal spacing, thus confirming intercalation of the BB41 molecules within the nanostructures of the interlayer spaces. Fourier transform infrared spectroscopy was used for identifying the functional groups and chemical bounding of Na+-montmorillonite, BB41 and montmorillonite-BB41. The morphology of NCP was also studied by transmission electron microscopy. Finally, thermo-gravimetric analysis and differential thermograms suggested the thermal stability of the intercalated dye was improved.
A new series of 2-(4-(4-aminophenylsulfonyl)phenylamino)-3-(thiophen-2-ylthio)naphthalene-1,4-dione derivatives (
A porous Pb foam was fabricated electrochemically at a copper substrate and then used as the cathode for the electroreduction of CO2. The surface morphology and composition of the porous Pb electrode was characterized by scanning electron microscopy, X-ray diffraction, transmission electron microscopy and selected area electron diffraction. The honeycomb-like porous structure was composed of needle-like Pb deposits. Cyclic voltammetry studies demonstrated that the porous Pb electrode had better electrocatalytic performance for the formation of formic acid from CO2 compared with a Pb plate electrode. The increase in current density was due to the large surface area of the porous Pb electrode, which provides more active sites on the electrode surface. The improved formic acid selectivity was due to the morphology of the roughened surface, which contains significantly more low-coordination sites which are more active for CO2 reduction. The highest current efficiency for formic acid was 96.8% at -1.7 V versus saturated calomel electrode at 5 °C. This porous Pb electrode with good catalytic abilities represents a new 3D porous material with applications for the electroreduction of CO2.
Canola oil and light cycle oil (LCO) blends were co-hydrotreated over a commercial hydrotreating catalyst (NiMo/Al2O3) to produce diesel fuel with a green diesel component. High hydrodeoxygenation, hydrodesulphurization and hydrodenitrogenation catalytic activities were achieved for all three feedstocks tested in the temperature range of 350–380 °C with a hydrogen pressure of 7 MPa and a gas/oil ratio of 800 nL/L. The hydrocracking conversion of the 360 °C+ materials in the feedstocks increased by 5% and 15% when 5 and 7.5 wt-% canola oil was added to the LCO, respectively. Compared to the pure LCO, the cetane index of the diesel product formed from hydrotreating the two canola oil-LCO blends increased by 2.5 and 4, respectively. Due to the higher hydrogen requirement to crack and deoxygenate the triglycerides contained in the canola oil, a higher hydrogen consumption was needed to hydrotreat the canola oil-LCO blends.
A novel method for the preparation of β-cyclodextrin grafted graphene oxide (GO-β-CD) has been developed. The GO-β-CD was characterized by Fourier transform infrared spectroscopy, 13C NMR spectroscopy, Raman spectroscopy and thermogravimetric analysis. The ability of GO-β-CD to remove fuchsin acid from solution was also studied. The GO-β-CD had an excellent adsorption capacity for fuchsin acid and could be recycled and reused. The adsorption capacities of GO-β-CD for other dye pollutants such as methyl orange and methylene blue were also investigated. The absorption capacities for the three dyes are in the order: fuchsin acid>methylene blue>methyl orange.
Membrane distillation (MD) is a thermal, vapor-driven transportation process through micro porous hydrophobic membranes that is increasingly being applied to seawater and brine desalination processes. Two types of hydrophobic microporous polyethersulfone flat sheet membranes, namely, annealed polyethersulfone and a polyethersulfone/tetraethoxysilane (PES/TEOS) blend were prepared by a phase inversion process. The membranes were characterized and their performances were investigated using the vacuum membrane distillation of an aqueous NaCl solution. The performances of the prepared membranes were also compared with two commercially available hydrophobic membranes, polytetrafluorethylene and polyvinylidene fluoride. The influence of operational parameters such as feed temperature (25–65 °C), permeate vacuum pressure (200–800 mbar), feed flow rate (8–22 mL/s) and feed salt concentration (3000 to 35000 mg/L) on the MD permeation flux were investigated for the four membranes. The hydrophobic PES/TEOS membrane had the highest salt rejection (99.7%) and permeate flux (86 kg/m2·h) at 65 °C, with a feed of 7000 ppm and a pressure of 200 mbar.
The sorption of water and organic vapors on valnemulin hydrochloride was determined by dynamic vapor sorption at 25 °C. The adsorption-desorption behavior of water vapor and a series of organic vapors was investigated to probe the structural changes in valnemulin hydrochloride before and after sorption. The isothermal adsorption equilibrium data was evaluated using Guggenheim-Anderson-deBoer (GAB) and Brunauer-Emmett-Teller (BET) models. The BET model is applicable only at low relative pressures (0.1≤RP≤0.4) while the GAB model is applicable in the whole range of RPs (0.1≤RP≤0.9). The sorption kinetics at high RPs was determined by fitting the sorption data to the Avrami equation and the sorption content vs. time relationship could be predicted by the Avrami equation. Finally, the possible sorption mechanism of valnemulin hydrochloride was also discussed.
The phase behavior of twelve synthesized β-sitosteryl fatty acid esters with acyl moieties with different chain lengths (C2:0-C18:0) and different degrees of unsaturation (C18:1-C18:3) were investigated in pure and mixed Langmuir monolayers with phospholipids. The surface-pressure isotherms showed that short chain β-sitosteryl fatty acid esters gave smaller mean molecular areas and had decreased monolayer stability and the long chain steryl esters did not produce collapsed plateaus. All the steryl esters displayed strong condensing effects, but there was a pronounced structural dependency: medium chain esters (C8 and C10) were less efficient than short and long chain esters. Atomic force microscopy imaging demonstrated that monolayers mixed with dipalmitoyl phosphatidylcholine (DPPC) displayed both DPPC-rich and steryl lipid-rich domains. However, the height and area differences between the two phases and the roughness and morphologic patterns were very dependent on the steryl lipid concentrations as well as the length, the degree of unsaturation and the molecular conformations of the acyl segments. These findings not only provide a better understanding of the interactions between phytosteryl hydrophobic derivatives and biomembranes, but also may be of general use for the design and engineering of phytosterol structural derivations for specific food and pharmaceutical applications.
Triacetone triperoxide (TATP) is more sensitive than diacetone diperoxide (DADP) in the solid-state explosion. To explain this reactivity difference, we analyzed the electronic structures and properties of the crystals of both compounds by using Ab initio method to calculate the structures of their individual molecules as well as their lattice structures and particularly calculating Nuclear Fukui function to gain insight into the sensitivity of the initial, rate-determining step of their decomposition. Our results indicate that TATP and DADP crystal structures exhibit significantly different electronic properties. Most notably, the electronic structure of the TATP crystal shows asymmetry among its reactive oxygen atoms as supported by magnitudes of their nuclear Fukui functions. The greater explosion sensitivity of crystalline TATP may be attributed to the properties of its electronic structure. The electronic calculations provided valuable insight into the decomposition sensitivity difference between TATP and DADP crystals.
