Curcumin nanoemulsion for transdermal application: formulation and evaluation

The aim of this work is to develop a curcumin nanoemulsion for transdermal delivery. The incorporation of curcumin inside a nanoglobul should improve curcumin stability and permeability. A nanoemulsion was prepared by the self-nanoemulsification method, using an oil phase of glyceryl monooleate, Cremophor RH40 and polyethylene glycol 400. Evaluation of the nanoemulsion included analysis of particle size, polydispersity index, zeta potential, physical stability, Raman spectrum and morphology. In addition, the physical performance of the nanoemulsion in Viscolam AT 100P gel was studied. A modified vertical diffusion cell and shed snake skin of Python reticulatus were used to study the in vitro permeation of curcumin. A spontaneously formed stable nanoemulsion has a loading capacity of 350?mg curcumin/10?g of oil phase. The mean droplet diameter, polydispersity index and zeta potential of optimized nanoemulsion were 85.0?±?1.5?nm, 0.18?±?0.0 and ?5.9?±?0.3?mV, respectively. Curcumin in a nanoemulsion was more stable than unencapsulated curcumin. Furthermore, nanoemulsification significantly improved the permeation flux of curcumin from the hydrophilic matrix gel; the release kinetic of curcumin changed from zero order to a Higuchi release profile. Overall, the developed nanoemulsion system not only improved curcumin permeability but also protected the curcumin from chemical degradation.     

The interplay between governmental communications and fellow citizens’ reactions via twitter: Experimental results of a theoretical crisis in the Netherlands

This study aimed to gain insight into the interplay between citizens’ reactions on Twitter and governmental communications as well as their effects on self‐reliant behaviour and trust. Two experimental studies were conducted. In Study 1, participants first received other citizens’ reactions followed by the government's communications about how to act. Participants received supporting, opposing, mixed, or no reactions from other citizens. In Study 2, participants first received the government's communications with either certain or uncertain crisis information, followed by the different citizens’ reactions. The results showed that citizens’ reactions via Twitter are not necessarily detrimental to the effectiveness of governmental communications regarding self‐reliant behaviour. In addition, our findings suggest being careful with providing uncertain governmental communications during a crisis.     

Modular Self‐Assembling Peptide Platform with a Tunable Thermoresponsiveness via a Single Amino Acid Substitution

The introduction of a stimulus‐responsive property is an effective way to increase the applicability of functional materials in the field of nanobiotechnology. Herein, a peptide platform is devised for constructing elastin‐like peptide amphiphiles (ELPAs) that exhibit a temperature‐responsiveness that can be easily tuned via a single N‐terminal amino acid substitution at the final step of peptide synthesis. Due to the modular property of peptides, the platform based on a miniaturized elastin‐like peptide (MELP) can be conjugated with various bioactive peptide sequences in diverse macromolecular topologies. First, the MELP platform is coupled with a short linear RGD peptide. The ELPAs of the peptide conjugates exhibit rapid aggregation (coacervation) and retard disaggregation in response to heating and cooling, respectively. Second, the platform is grafted with an α‐helical guest peptide in a lariat‐type structure, which forms ELPAs that undergo faster disassembly than the ELPAs without the guest peptide in response to temperature increases. Interestingly, the critical temperatures for the thermoresponsive behaviors are commonly dependent on the hydrophobic and aromatic properties of the N‐terminal amino acid residues. These results suggest that this peptide platform possesses great potential for use in the development of smart materials in wide‐ranging applications related to temperature change.     

One‐Step Construction of N,P‐Codoped Porous Carbon Sheets/CoP Hybrids with Enhanced Lithium and Potassium Storage

Despite the desirable advancement in synthesizing transition‐metal phosphides (TMPs)‐based hybrid structures, most methods depend on foreign‐template‐based multistep procedures for tailoring the specific structure. Herein, a self‐template and recrystallization–self‐assembly strategy for the one‐step synthesis of core–shell‐like cobalt phosphide (CoP) nanoparticles embedded into nitrogen and phosphorus codoped porous carbon sheets (CoP?NPPCS), is first proposed. Relying on the unusual coordination ability of melamine with metal ions and the cooperative hydrogen bonding of melamine and phytic acid to form a 2D network, a self‐synthesized single precursor can be attained. Importantly, this approach can be easily expanded to synthesize other TMPs?NPPCS. Due to the unique compositional and structural characteristics, these CoP?NPPCSs manifest outstanding electrochemical performances as anode materials for both lithium‐ and potassium‐ion batteries. The unusual hybrid architecture, the high specific surface area, and porous features make the CoP?NPPCS attractive for other potential applications, such as supercapacitors and electrocatalysis.     

Solvent‐Controlled Assembly of Aromatic Glutamic Dendrimers for Efficient Luminescent Color Conversion

A binary supramolecular system where self‐sorting and coassembly behavior can be switched by changing the solvent polarity is hereby reported. Glutamic dendron is separately conjugated with pyrene and naphthalimide luminophores through an alkyl spacer. The resulting structurally similar building units can self‐assemble into one‐dimensional micro/nanostructures with hexagonal and lamellar packing, respectively. Varying solvents from polar aqueous solution to nonpolar decane is evidenced to profoundly inverse the superchirality and switch self‐sorted assembly to coassembly of the two building blocks. The moisture sensitivity of the naphthalimide moiety is considered the primary driving force for the self‐sorting phenomenon in aqueous solution, resulting in inevitable hydration to repel its stacking with hydrophobic pyrene moiety. On the other hand, the naphthalimide unit can integrate segmentally with the pyrene unit in decane, greatly facilitating the nanofiber growth and supramolecular gel formation along with improved energy transfer efficiency between luminophores. As a result, the coassembly‐based thin films show efficient luminescent color conversion upon the UV light irradiation. This research presents a useful route for the fabrication of controllable solution‐processed light emitting devices from self‐assembled multicomponent systems.     

Design and optimization of radioisotope sources for betavoltaic batteries

A Monte Carlo source model using PENELOPE was developed to investigate different tritiated metals in order to design a better radioisotope source for betavoltaic batteries. The source model takes into account the self‐absorption of beta particles in the source which is a major factor for an efficient source design. The average beta energy, beta flux, source power output, and source efficiency were estimated for various source thicknesses. The simulated results for titanium tritide with 0° and 90° angular distributions of beta particles were validated with experimental results. The importance of the backscattering effect due to isotropic particle emission was analyzed. The results showed that the normalized average beta energy increases with the source thickness, and it reaches peak energy depending on the density and the specific activity of the source. The beta flux and power output also increase with increasing source thickness. However, the incremental increase in beta flux and power output becomes minimal for higher thicknesses, as the source efficiency decreases significantly at higher thicknesses due to the self‐absorption effect. Thus, a saturation threshold is reached. A low‐density source material such as beryllium tritide provided a higher power output with higher efficiency. A maximum power output of approximately 4 mW/cm³ was obtained for beryllium tritide with SiC. A form factor approach was used to estimate the optimum source thickness. The optimum source thickness was found near the thickness where the peak beta particle average energy occurs.     

自交联水性聚氨酯-含氟丙烯酸酯乳液的制备及研究

以异佛尔酮二异氰酸酯(IPDI)、聚碳酸酯二醇(PCDL)、二羟甲基丁酸(DMBA)、1,4-丁二醇(BDO)、甲基丙烯酸羟乙酯(HEMA)为原料合成了双键封端的聚氨酯预聚体;以N-羟乙基丙烯酰胺(HEAA)作交联剂,配合甲基丙烯酸六氟丁酯(HFBMA)等单体进行乳液共聚,制备了自交联水性聚氨酯-含氟丙烯酸酯(FPUA)乳液。研究了HFBMA和HEAA用量对膜耐水性、热性能以及力学性能的影响。结果表明:PUA乳液的耐水性和疏水性随HFBMA用量的增加而增加;随着HEAA用量增加,胶膜的热稳定性增加,拉伸强度增加,伸长率下降;当胶膜中HFBMA质量分数为12%,且HEAA质量分数为2.6%时,乳液的粒径为128 nm,乳液的稳定性较好;胶膜的水接触角为107.6°,吸水率为4.5%,拉伸强度为25.6 MPa,断裂伸长率为268%,10%热失重温度299.6℃。     

Why self‐cleaning is important for solar thermal receivers?

Surface cleaning remains essential for the sustainable operation of high performance solar thermal receivers. Cleaning of optical surfaces, such as solar troughs and absorbers, requires energy intensive efforts because of the large surface area involvement such as those observed in solar farms. In addition, self‐cleaning of such surfaces becomes demanding because of lowering the cleaning costs, reducing the waste of resources, such as clean water, and minimizing the complication of the mechanical systems incorporated. Self‐cleaning of surfaces is associated with the low adhesion between the surface and the foreign particles; in which case, these particles can be removed easily from the surfaces in a cost‐effective way. The surface energy and contact area of the surface are two main important parameters influencing the particle adhesion on the surfaces. In this case, reducing the surface energy and forming micro/nano size pillars on the surface through texturing lower the particle adhesion on the surfaces significantly. In solar thermal energy harvesting applications, metallic or composite materials are used and texturing the surface remains challenging in terms of cost and precision of operation when conventional texturing methods are used. One of the methods to create surface texture consisting of micro/nano pillars is to use the laser beam ablation. This results in hierarchical distribution of surface texture with desired pillar heights1. In addition, laser surface texturing offers significant advantages over the conventional techniques. Some of these advantages include fast processing, precision of operation, and low cost. Although the laser processing involves with high temperature processing and thermally induced stresses remain important, the defects sites can be minimized via controlling the process parameters during the texturing. Introducing the assisting gas on the texturing surface enables to generate compounds such as oxide or nitride species, which lower the surface energy considerably. Consequently, investigation of laser texturing of solar energy materials while incorporating the assisting gas becomes essential. In the present perspective, the laser surface texturing of solar energy materials for thermal power applications is presented together with challenges and future perspectives. Specifically, the followings will be presented: (1) the texture characteristics of laser treated metallic and ceramic surfaces; (2) wetting state of the textured surface, and optical properties of textured surface in terms of absorption of the solar irradiation.