Breakdown and Modification of Microplastic Beads by Aeolian Abrasion

Saltation is an important wind erosion process that can cause the modification and breakdown of particles by aeolian abrasion. It is recognized that microplastic particles can be transported by wind, but the effect of saltation on microplastic properties is unknown. This study examined the impact of simulated saltation alongside quartz grains on the size, shape, and surface properties of spherical microplastic beads. The diameter of the microplastics was reduced by 30–50% over 240–300 h of abrasion with a mass loss of c. 80%. For abrasion periods up to 200 h, the microplastic beads remained spherical with minimal change to overall shape. Over 95% of the fragments of plastic removed from the surface of the microbeads during the abrasion process had a diameter of ≤10 μm. In addition, during the abrasion process, fine particles derived from breakdown of the quartz grains became attached to the surfaces of the microbeads resulting in a reduction in carbon and an increase in silicon detected on the particle surface. The results suggest that microplastics may be mechanically broken down during aeolian saltation and small fragments produced have the potential for long distance transport as well as being within the size range for human respiration

Nano Ag sintering on Cu substrate assisted by self-assembled monolayers for high-temperature electronics packaging

Sintering of nano Ag paste on bare Cu has attracted more interests recently for high-temperature electronics packaging, which offers the advantages of high reliability, cost-effective and direct bonding process. However, the current bonding methods normally need a protective atmosphere or metallization on Cu substrate to avoid oxidation. In this study, self-assembled monolayers (SAMs) were deposited on Cu substrate to suppress oxidation prior to nano Ag sintering. Thermal-compression bonding process of Cu/nano Ag/Cu joints was conducted and analysed with and without SAMs treatment. The cross-sectional characterization and shear tests were conducted to evaluate the influence of SAMs treatment. When SAMs applied, shear strength of 12.72 MPa has been achieved in the ambient atmosphere, which is much higher than the value without SAMs treatment (3.77 MPa). It has been identified that the shear mode changed from the interfaces of sintered nano Ag/Cu to inside of sintered nano Ag due to the applied SAMs. This technological approach provides a tangible and cost-effective method for high temperature electronics packaging

Graphite grain boundary structures

Images and data files for the images in figure 9 in the paper entitled "Mesoscopic structure features in synthetic graphite".Structures generated using code available here:https://github.com/Kenny-Jolley/Graphene<br

Synthesis of Gold Nanoparticles Using the Interface of an Emulsion Droplet

A facile and rapid method for synthesizing single crystal gold spherical or platelet (nonspherical) particles is reported. The reaction takes place at the interface of two immiscible liquids where the reducing agent decamethyl­ferrocene (DmFc) was initially added to hexane and gold chloride (AuCl₄^–) to an aqueous phase. The reaction is spontaneous at room temperature, leading to the creation of Au nanoparticles (AuNP). A flow focusing microfluidic chip was used to create emulsion droplets, allowing the same reaction to take place within a series of microreactors. The technique allows the number of droplets, their diameter, and even the concentration of reactants in both phases to be controlled. The size and shape of the AuNP are dependent upon the concentration of the reactants and the size of the droplets. By tuning the reaction parameters, the synthesized nanoparticles vary from nanometer to micrometer sized spheres or platelets. The surfactant used to stabilize the emulsion was also shown to influence the particle shape. Finally, the addition of other nanoparticles within the droplet allows for core@shell particles to be readily formed, and we believe this could be a versatile platform for the large scale production of core@shell particles

ZnO Micro/Nanocrystals with Tunable Exposed (0001) Facets for Enhanced Catalytic Activity on the Thermal Decomposition of Ammonium Perchlorate

ZnO micro/nanocrystals with different percentages of the exposed (0001) facets were synthesized by a facile chemical bath deposition method. Various characterizations were carried out to understand the relationship between particle shape, exposed (0001) facets, and catalytic activity of ZnO nanocrystals for the thermal decomposition of ammonium perchlorate (AP). An enhancement in the catalytic activity was observed for the ZnO micro/nanocrystals with a higher percentage of the exposed (0001) facets, in which the activation energy <i>E</i>_a of AP decomposition was lowered from 154.0 ± 13.9 kJ/mol to 90.8 ± 11.4 kJ/mol, 83.7 ± 15.1 kJ/mol, and 63.3 ± 3.7 kJ/mol for ZnO micro/nanocrystals with ca. 18.6%, 20.3%, and 39.3% of the exposed (0001) facets. Theoretically evidenced by density functional theory calculations, such highly exposed (0001) facets can be favorable for the adsorption and diffusion of perchloric acid, and also facilitate the formation of active oxygen which can lead to the oxidation reaction of ammonia more completely in the catalytic decomposition of AP

Kernel density estimate showing the distribution of antibiotic coverage.

<p>Antibiotic coverage data was available for 38 of 40 villages. The density plot was computed using the Epanechnikov kernel function, Sheather-Jones plug-in bandwidth estimate, and upper boundary correction using the renormalization method.</p

Predicted chlamydial infection after a single mass azithromycin treatment, with varying levels of antibiotic coverage.

<p>Post-treatment chlamydial prevalence in 1–5 year old children was calculated for a hypothetical community treated with a single mass azithromycin treatment, in which 48.9% of 1–5 year old children were infected at baseline. Antibiotic coverage was significantly associated with post-treatment infection at two months (2A; <i>R</i>² = 0.53, <i>p</i> = 0.007), but not at six months (2B; <i>R</i>² = 0.35, <i>p</i> = 0.31). The upper and lower curves are the boundaries of the 95% confidence interval for the predicted mean.</p

Wasting, low MUAC, stunting, and underweight in children aged 6–60 months from 24 communities randomized (1∶1) to annual or biannual mass azithromycin treatment.

<p>*Mixed effects logistic regression with community as a random effect. All measurements are based on Z score<−2.0. Numbers may be different because of some loss during field examination.</p><p>MUAC: mid-upper arm circumference.</p><p>Wasting, low MUAC, stunting, and underweight in children aged 6–60 months from 24 communities randomized (1∶1) to annual or biannual mass azithromycin treatment.</p

Baseline characteristics of 24 communities randomized (1∶1) to annual or biannual mass azithromycin treatments in a cluster randomized clinical trial for trachoma in Niger.

<p>*TF, trachomatous inflammation - follicular; TI, trachomatous inflammation – intense, both from a random sample of children aged ≤30 months of age.</p><p>**p-values: All Wilcoxon rank-sum except linear mixed effects regression for age of children.</p><p>Baseline characteristics of 24 communities randomized (1∶1) to annual or biannual mass azithromycin treatments in a cluster randomized clinical trial for trachoma in Niger.</p

Anthropometric Z-scores in children aged 6–60 months from 24 communities randomized (1∶1) to annual or biannual mass azithromycin treatment.

<p>*Pseudomedian (Hodges-Lehmann estimator) difference between the biannual arm and annual arm. Positive values correspond to larger measurements in the biannual arm.</p><p>WHZ: weight-for-height z-score.</p><p>MUACZ: mid-upper arm circumference z-score.</p><p>HAZ: height-for-age z-score.</p><p>WAZ: weight-for-age z-score.</p><p>Anthropometric Z-scores in children aged 6–60 months from 24 communities randomized (1∶1) to annual or biannual mass azithromycin treatment.</p