In this work, the effect of varying the size of the precursor raw materials SiO
2
and ZrO
2
in the solid-state synthesis of NASICON in the form Na
3
Zr
2
Si
2
PO
12
was studied. Nanoscale and ...macro-scale precursor materials were selected for comparison purposes, and a range of sintering times were examined (10, 24 and 40 h) at a temperature of 1230 °C. Na
3
Zr
2
Si
2
PO
12
pellets produced from nanopowder precursors were found to produce substantially higher ionic conductivities, with improved morphology and higher density than those produced from larger micron-scaled precursors. The nanoparticle precursors were shown to give a maximum ionic conductivity of 1.16 × 10
−3
S cm
−1
when sintered at 1230 °C for 40 h, in the higher range of published solid-state Na
3
Zr
2
Si
2
PO
12
conductivities. The macro-precursors gave lower ionic conductivity of 0.62 × 10
−3
S cm
−1
under the same processing conditions. Most current authors do not quote or consider the precursor particle size for solid-state synthesis of Na
3
Zr
2
Si
2
PO
12
. This study shows the importance of precursor powder particle size in the microstructure and performance of Na
3
Zr
2
Si
2
PO
12
during solid-state synthesis and offers a route to improved predictability and consistency of the manufacturing process.
The effect of a variety of metal-chlorides additions on the melting behavior and thermal stability of commercially available salts was investigated. Ternary salts comprised of KNO
NaNO
and NaNO
were ...produced with additions of a variety of chlorides (KCl, LiCl, CaCl
, ZnCl
, NaCl and MgCl
). Thermogravimetric analysis and weight loss experiments showed that the quaternary salt containing a 5 wt% addition of LiCl and KCl led to an increase in short term thermal stability compared to the ternary control salts. These additions allowed the salts to remain stable up to a temperature of 630 °C. Long term weight loss experiments showed an upper stability increase of 50 °C. A 5 wt% LiCl addition resulted in a weight loss of only 25% after 30 hours in comparison to a 61% loss for control ternary salts. Calorimetry showed that LiCl additions allow partial melting at 80 °C, in comparison to the 142 °C of ternary salts. This drop in melting point, combined with increased stability, provided a molten working range increase of almost 100 °C in total, in comparison to the control ternary salts. XRD analysis showed the oxidation effect of decomposing salts and the additional phase created with LiCl additions to allow melting point changes to occur.
•Additions of up to1.8 wt. % Ge in Zn-1.6 wt. % Al-1.6 wt. % Mg.•SVET and time lapse microscopy study of Zn-Al-Mg-Ge corroding in NaCl.•Ge additions result in formation of new Mg2Ge phase within the ...microstrusture.•Reduction in SVET derived mass loss and corroded area with increasing Ge levels.•Dissolving Mg2Ge acts as source of Mg2+ resulting in stabilisation of Zn surface.
In-situ scanning vibrating electrode technique and time-lapse microscopy are used to investigate the influence of germanium additions (0.19–1.8 wt.%) on the corrosion performance of zinc-aluminium-magnesium model alloys immersed in 0.17 mol.dm−3 NaCl. The addition of Ge results in the formation of Mg2Ge and a decrease in the fractional area of eutectic phase. A 58 % decrease in SVET derived mass loss is achieved at 1.8 wt.% Ge. It is proposed that Mg2Ge crystals are anodically attacked and behave as reservoirs of Mg2+ ions. Mg(OH)2 is precipitated and local electrolyte pH stabilises to values at which the zinc surface is passive.
The correlative imaging workflow is a method of combining information and data across modes (e.g. SEM, X‐ray CT, FIB‐SEM), scales (cm to nm) and dimensions (2D–3D–4D), providing a more holistic ...interpretation of the research question. Often, subsurface objects of interest (e.g. inclusions, pores, cracks, defects in multilayered samples) are identified from initial exploratory nondestructive 3D tomographic imaging (e.g. X‐ray CT, XRM), and those objects need to be studied using additional techniques to obtain, for example, 2D chemical or crystallographic data. Consequently, an intermediate sample preparation step needs to be completed, where a targeted amount of sample surface material is removed, exposing and revealing the object of interest. At present, there is not one singular technique for removing varied thicknesses at high resolution and on a range of scales from cm to nm. Here, we review the manual and automated options currently available for targeted sample material removal, with a focus on those methods which are readily accessible in most laboratories. We summarise the approaches for manual grinding and polishing, automated grinding and polishing, microtome/ultramicrotome, and broad‐beam ion milling (BBIM), with further review of other more specialist techniques including serial block face electron microscopy (SBF‐SEM), and ion milling and laser approaches such as FIB‐SEM, Xe plasma FIB‐SEM, and femtosecond laser/LaserFIB. We also address factors which may influence the decision on a particular technique, including the composition, shape and size of the samples, sample mounting limitations, the amount of surface material to be removed, the accuracy and/or resolution of peripheral parts, the accuracy and/or resolution of the technique/instrumentation, and other more general factors such as accessibility to instrumentation, costs, and the time taken for experimentation. It is hoped that this study will provide researchers with a range of options for removal of specific amounts of sample surface material to reach subsurface objects of interest in both correlative and non‐correlative workflows.
The development of lightweight and flexible solar modules is highly desirable for high specific power applications, building integrated photovoltaics, unmanned aerial vehicles and space. Flexible ...metallic and polyimide foils are frequently used, but in this work an alternative substrate with attractive properties, ultra-thin glass (UTG) has been employed. CdTe solar cells with average efficiency reaching 14.7% AM1.5G efficiency have been produced on UTG of 100 μm thickness. Little has been reported on the effects on PV performance when flexed, so we investigated the effects on J-V parameters when the measurements were performed in 40 mm and 32 mm bend radius, and in a planar state before and after the bend curvature was applied. The flat J-V measurements after 32 mm bending test showed some improvement in efficiency, Voc and FF, with values higher than the first measurement in a planar state. In addition, two CdTe solar cells with identical initial performance were subjected to 32 mm static bending test for 168 hours, the results showed excellent uniformity and stability and no significant variation on J-V parameters was observed. External quantum efficiency and capacitance voltage measurements were performed and showed no significant change in spectral response or carrier concentration. Residual stress analysis showed that no additional strain was induced within the film after the bending test and that the overall strain was low. This has demonstrated the feasibility of using CdTe solar cells on UTG in new applications, when a curved module is required without compromising performance.
•CdTe solar cell on flexible ultra-thin glass was successfully produced with average efficiency reaching 14.7%.•Effect of photovoltaic characteristics under 40 mm and 32 mm bend radius are revealed.•Performances were compared to the measurements in a planar state before and after bending test.•The impact of bending test on EQE, C-V and residual stress measurements were analysed.
Printed mesoscopic carbon perovskite solar cells (CPSCs) represent a potential frontrunner to perovskite commercialisation due to their inherent stability and easily scaled fabrication methods. ...Devices consist of three screen printed mesoporous layers of TiO
2
, ZrO
2
and carbon, which are subsequently infiltrated with perovskite. It is well established that complete infiltration, or filling, of the base TiO
2
layer is key to achieving peak performance and reproducibility in both lab-scale devices and modules. A thorough understanding of the factors influencing infiltration is therefore essential for both lab-scale research and scale-up. TiO
2
infiltration is easily examined by optical microscopy through the glass substrate. This work identifies common characteristic infiltration defects at multiple scales, caused by specific issues in the manufacturing process such as mesh marking, printing issues, contaminant damage and environmental fluctuations. Likely causes and potential solutions are presented for each type of defect, to produce a troubleshooting reference resource for tackling this problem at multiple scales. This should help enhance lab-scale reproducibility providing a simple method for quality control in future large-scale ventures.
Characteristic CPSC infiltration defects are identified and linked to specific manufacturing issues. Preventative solutions are presented, to produce a troubleshooting reference resource for tackling poor infiltration at multiple scales.
Summary
Background
Excessive skin exposure to solar radiation damages proteins and DNA, ultimately leading to skin ageing and cancers.
Objectives
To identify new ultraviolet B (UVB) target genes to ...understand the mechanisms behind the detrimental effects of UVB.
Methods
Organotypic, stratified cultures of rat keratinocytes were exposed to UVB and analysed using a genome‐wide expression array, quantitative real‐time polymerase chain reaction and histology. The most downregulated gene, rClca2, was further characterized in rat keratinocytes and mouse skin models.
Results
A single, 30 mJ cm−2 dose of broadband UVB proved effective in the organotypic epidermal culture. The expression of 627 genes was changed 24 h postirradiation. In silico analysis of the data indicated activation of DNA repair, metabolism, cell cycle control and amino acid metabolism, but only limited inflammation under these conditions. We selected for further investigation the most downregulated gene, rClca2, previously suggested to regulate keratinocyte differentiation and adhesion, and found that UVB caused a long‐lasting downregulation in its expression. Both the rClca2 full‐length isoform (expressed in the differentiating cells) and the truncated isoform (expressed in the basal layers) were reduced by UVB. Immunohistochemistry of mouse skin samples with isoform‐specific antibodies showed a similar, epidermal differentiation‐related pattern. In mouse specimens exposed to chronic ultraviolet radiation (UVR) the staining intensities were reduced and the differentiation‐related isoform was disturbed in the hyperplastic and carcinomatous areas induced by UVR.
Conclusions
The data show that rClca2 is a novel UVB target gene and suggest that it might play a role in epidermal differentiation and UV‐dependent skin malignancies.
What's already known about this topic?
Excessive exposure to ultraviolet radiation causes inflammation, immune suppression and mutations, and can ultimately lead to cancer.
What does this study add?
Novel ultraviolet B (UVB) target genes related to calcium signalling were identified in organotypic epidermal cultures.
The gene most downregulated by UVB was rClca2, a chloride channel‐associated protein, expressed as two isoforms in epidermis, in a differentiation‐related manner.
Mesoscopic carbon-based perovskite solar cells (CPSCs) are frequently described as a potential frontrunner for PSC commercialization. Previous work has introduced γ-valerolactone (GVL) as a ...sustainable, non-toxic, green alternative to GBL for CPSC perovskite precursors. In this work, methanol (MeOH) solvent additives are applied to enhance the performance and reproducibility of GVL-based precursors, through improving electrode wetting, infiltration, and perovskite crystal quality. Precursors incorporating 10% MeOH are found to substantially enhance reproducibility and performance, achieving a champion PCE of 13.82% in a 1 cm
2
device and >9% in a 220 cm
2
module fabricated in ambient conditions. Stability is also improved, with an unencapsulated MeOH device exhibiting a T80 of >420 hours at 50 °C in ambient humidity under continuous AM1.5 illumination. This work established GVL-based precursors as commercially attractive and provides an example of how green solvent engineering can be applied in the development, amelioration and scale-up of novel photovoltaics.
Green solvent mixes are applied in printed mesoscopic perovskite solar cells and modules, achieving 13.8% PCE at 1 cm
2
and >9% PCE in a 220 cm
2
module. This shows how green solvent engineering can aid improvement and scale-up in emerging technologies.
ABSTRACTSince mammalian skin expresses the enzymatic apparatus for melatonin synthesis, it may be an extrapineal site of melatonin synthesis. However, evidence is still lacking that this is really ...the case in situ. Here, we demonstrate melatonin‐like immunoreactivity (IR) in the outer root sheath (ORS) of mouse and human hair follicles (HFs), which corresponds to melatonin, as shown by radioimmunoassay and liquid chromatography/tandem mass spectrometry (LC/MS/MS). The melatonin concentration in organ‐cultured mouse skin, mouse vibrissae follicles, and human scalp HFs far exceeds the respective melatonin serum level and is significantly increased ex vivo by stimulation with norepinephrine (NE), the key stimulus for pineal melatonin synthesis. By real‐time PCR, transcripts for the melatonin membrane receptor MT2 and for the nuclear mediator of melatonin signaling, retinoid orphan receptor α (ROR)α, are detectable in murine back skin. Transcript levels for these receptors fluctuate in a hair cycle‐dependent manner, and are maximal during apoptosis‐driven HF regression (catagen). Melatonin may play a role in hair cycle regulation, since its receptors (MT2 and RORα) are expressed in murine skin in a hair cycle‐dependent manner, and because it inhibits keratinocyte apoptosis and down‐regulates ERα expression. Therefore, the HF is both, a prominent extrapineal melatonin source, and an important peripheral melatonin target tissue. Regulated intrafollicular melatonin synthesis and signaling may play a previously unrecognized role in the endogenous controls of hair growth, for example, by modulating keratinocyte apoptosis during catagen and by desensitizing the HF to estrogen signaling. As a prototypic neuroectodermal‐mesodermal interaction model, the HF can be exploited for dissecting the obscure role of melatonin in such interactions in peripheral tissues.
Among the thousands of paintings that Impressionists and Post-Impressionists created in southern France, several focus specifically on the subject of the Mistral. Here, Dunlop explores three of these ...paintings: Claude Monet's Cap d'Antibes, Mistral (1888), Paul Gauguin's Les Arlésiennes (Le Mistral) (1888), and Vincent van Gogh's Cypresses with Two Figures (1889). While the three paintings are quite different from one another in their style and subject matter, they all express the same paradox that characterized European interactions with the wind during the late 19th century.
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