Abstract Food-grade titanium dioxide (TiO 2 ) containing a nanoscale particle fraction (TiO 2 -NPs) is approved as a white pigment (E171 in Europe) in common foodstuffs, including confectionary. ...There are growing concerns that daily oral TiO 2 -NP intake is associated with an increased risk of chronic intestinal inflammation and carcinogenesis. In rats orally exposed for one week to E171 at human relevant levels, titanium was detected in the immune cells of Peyer’s patches (PP) as observed with the TiO 2 -NP model NM-105. Dendritic cell frequency increased in PP regardless of the TiO 2 treatment, while regulatory T cells involved in dampening inflammatory responses decreased with E171 only, an effect still observed after 100 days of treatment. In all TiO 2 -treated rats, stimulation of immune cells isolated from PP showed a decrease in Thelper (Th)-1 IFN-γ secretion, while splenic Th1/Th17 inflammatory responses sharply increased. E171 or NM-105 for one week did not initiate intestinal inflammation, while a 100-day E171 treatment promoted colon microinflammation and initiated preneoplastic lesions while also fostering the growth of aberrant crypt foci in a chemically induced carcinogenesis model. These data should be considered for risk assessments of the susceptibility to Th17-driven autoimmune diseases and to colorectal cancer in humans exposed to TiO 2 from dietary sources.
We report on the evidence of negative capacitance values in a system consisting of metal-semiconductor-metal (MSM) structures, with Schottky junctions made of zinc oxide thin films deposited by ...Atomic Layer Deposition (ALD) on top of platinum interdigitated electrodes (IDE). The MSM structures were studied over a wide frequency range, between 20 Hz and 1 MHz. Light and mechanical strain applied to the device modulate positive or negative capacitance and conductance characteristics by tuning the flow of electrons involved in the conduction mechanisms. A complete study was carried out by measuring the capacitance and conductance characteristics under the influence of both dark and light conditions, over an extended range of applied bias voltage and frequency. An impact-loss process linked to the injection of hot electrons at the interface trap states of the metal-semiconductor junction is proposed to be at the origin of the apparition of the negative capacitance values. These negative values are preceded by a local increase of the capacitance associated with the accumulation of trapped electrons at the interface trap states. Thus, we propose a simple device where the capacitance values can be modulated over a wide frequency range via the action of light and strain, while using cleanroom-compatible materials for fabrication. These results open up new perspectives and applications for the miniaturization of highly sensitive and low power consumption environmental sensors, as well as for broadband impedance matching in radio frequency applications.
Polylactide (PLA) was blended by conventional and reactive extrusion with limonene (LM) or myrcene (My) as bio-based plasticizers. As-processed blends were carefully analyzed by a multiscale and ...multidisciplinary approach to tentatively determine their chemical structure, microstructure, thermal properties, tensile and impact behaviors, and hydrothermal stability. The main results indicated that LM and My were efficient plasticizers for PLA, since compared to neat PLA, the glass transition temperature was reduced, the ultimate tensile strain was increased, and the impact strength was increased, independently of the type of extrusion. The addition of a free radical initiator during the extrusion of PLA/LM was beneficial for the mechanical properties. Indeed, the probable formation of local branched/crosslinked regions in the PLA matrix enhanced the matrix crystallinity, the tensile yield stress, and the tensile ultimate stress compared to the non-reactive blend PLA/LM, while the other properties were retained. For PLA/My blends, reactive extrusion was detrimental for the mechanical properties since My polymerization was accelerated resulting in a drop of the tensile ultimate strain and impact strength, and an increase of the glass transition temperature. Indeed, large inclusions of polymerized My were formed, decreasing the available content of My for the plasticization and enhancing cavitation from inclusion-matrix debonding.
Chemical Solution Deposition enables low‐cost fabrication of ferroelectric HfO2 films suitable for piezoelectric applications. Control of processing parameters is of utmost importance to obtain ...high‐quality functional films. However, the impact of the annealing atmosphere on ferroelectric properties of solution‐processed HfO2 films is not clear. In this work, the influence of annealing atmosphere and growth methods on orientation, density and electrical properties of La:HfO2 films is studied. The 45 nm‐thick films are grown by two routes, conventional (crystallization of the final 45 nm‐thick film) and layer‐by‐layer (intermediate crystallizations of 5 nm‐thick films). Annealing is performed in N2:O2 and Ar atmosphere. Films grown by layer‐by‐layer method in an oxygen‐rich atmosphere tend to have higher density (87% of theoretical density) and remanent polarization (15 µC cm–2) than the conventional films (density and remanent polarization of 80% and 7.5 µC cm‐2). Secondary ion mass spectrometry reveals higher amounts of carbon presence in the conventional films annealed in Ar. For layer‐by‐layer films, the ability to control the preferential out‐of‐plane orientation from (111) to (002) simply by changing the annealing atmosphere, is demonstrated. The results can guide the path toward high‐quality thicker films for piezoelectric applications.
This report introduces a simple method for controlling orientation in solution‐processed ferroelectric La:HfO2 thin films through layer‐by‐layer crystallization and control of annealing atmosphere. By introducing oxygen in the atmosphere, a straightforward approach to achieve 002 orientation is presented. As the polarization aligns parallel to the applied electric field, measured remanent polarization reaches a high value of 15 µC cm−2.
Microorganisms in biological wastewater treatment plants require adaptive strategies to deal with rapidly fluctuating environmental conditions. At the population level, the filamentous bacterium ...Candidatus Microthrix parvicella (Ca. M. parvicella) has been found to fine-tune its gene expression for optimized substrate assimilation. Here we investigated in situ substrate assimilation by single cells of Ca. M. parvicella using nano-scale secondary-ion mass spectrometry (nanoSIMS). NanoSIMS imaging highlighted phenotypic heterogeneity among Ca. M. parvicella cells of the same filament, whereby (13)C-oleic acid and (13)C-glycerol-3-phosphate assimilation occurred in ≈21-55% of cells, despite non-assimilating cells being intact and alive. In response to alternating aerobic-anoxic regimes, (13)C-oleic acid assimilation occurred among subpopulations of Ca. M. parvicella cells (≈3-28% of cells). Furthermore, Ca. M. parvicella cells exhibited two temperature optima for (13)C-oleic acid assimilation and associated growth rates. These results suggest that phenotypic heterogeneity among Ca. M. parvicella cells allows the population to adapt rapidly to fluctuating environmental conditions facilitating its widespread occurrence in biological wastewater treatment plants.
Simultaneously inducing preferred crystalline orientation with a strong piezoelectric response in polycrystalline aluminum nitride (AlN) thin films by atomic layer deposition is a technical challenge ...due to the upscaling of the integration of piezoelectric functionalities, such as sensing and actuation, in micro-devices without any poling process. Utilizing low-temperature plasma-enhanced atomic layer deposition (PE-ALD), highly c-axis-oriented AlN films have been prepared with precise control over the relative composition, purity levels, and chemical states of constituent elements. Tailoring thermodynamic parameters, such as the growth temperature and purging time after the trimethylaluminum precursor pulsing before the N2:H2:Ar plasma reaction, provide the possibility of modulating the texture coefficient and the relative piezoelectric response. The effective transverse piezoelectric e31,f coefficient of 0.37 C/m2 was achieved on the AlN film grown at 250 °C and 30 s with the highest texture coefficient TC(002) of 2.75 along the c-axis orientation. The process proposed, at a low temperature with the highly conformal growth of aluminum nitride thin films by PE-ALD, opens up pathways to design novel piezoelectric functional materials for micro-electro-mechanic system devices with complementary metal oxide semiconductor process temperature compatibility.
Microcarriers (MCs, typically 50–200 µm) are promising growth supports for high-throughput cell expansion, with capability to overcome the limitations of surface area availability and nutrient access ...encountered by cell culture in 2D well plate configurations. Equipping MCs with in-built capability to sense molecular biomarkers is a key step forward to meet the emerging demands of personalized cell-based therapies. However, integrating sensing functionality into MCs is non-trivial due to fabrication limitations imposed by their large size, curved surfaces, and their suspension in fluid. If achieved, the sensor-integrated MCs should face further concerns of reduced stability and cytocompatibility during cell-culture. Here we demonstrate plasmonic microcarriers (PMCs) that integrate spectroscopic sensing and cell expansion functions through the deposition of gold nanoparticle (AuNP) assemblies on dextran-based MCs. Hydrogel characteristics of the dextran microcarriers was found to profoundly enhance the binding density and kinetics of AuNPs, as seen by attainment of saturated densities in few seconds, and at nanoparticle concentrations only twice that of the surface sites. The approaches to prepare PMCs are distinguished by simple, scalable routes, without need for sophisticated lab infrastructure. The capability of PMCs to act as spectroscopic transducers was demonstrated by surface-enhanced spectroscopic (SERS) detection of a model molecular probe. The growth, proliferation and migration of human mesenchymal stem cells on the PMCs was found to be comparable to that of the uncoated MCs. The results pave the way to smart, multifunctional cell growth supports to interrogate, control and report cell behavior during culture.
To investigate the nature and origins of growth rate diversity in bacteria, we grew
and
in liquid minimal media and, after different periods of
N-labeling, analyzed and imaged isotope distributions ...in individual cells with
. We find a striking inter- and intra-cellular diversity, even in steady state growth. This is consistent with the strand-dependent, hyperstructure-based hypothesis that a major function of the cell cycle is to generate coherent, growth rate diversity via the semi-conservative pattern of inheritance of strands of DNA and associated macromolecular assemblies. We also propose quantitative, general, measures of growth rate diversity for studies of cell physiology that include antibiotic resistance.
A set of poly(isobornyl methacrylate)s (PIBOMA) having molar mass in the range of 26,000–283,000 g mol−1 was prepared either via RAFT process or using free radical polymerization. These linear ...polymers demonstrated high glass transition temperatures (Tg up to 201 °C) and thermal stability (Tonset up to 230 °C). They were further applied as reinforcing agents in the preparation of the vulcanized rubber compositions based on poly(styrene butadiene rubber) (SBR). The influence of the PIBOMA content and molar mass on the cure characteristics, rheological and mechanical properties of rubber compounds were studied in detail. Moving die rheometry revealed that all rubber compounds filled with PIBOMA demonstrated higher torque increase values ΔS in comparison with rubber compositions without filler, independent of PIBOMA content or molar mass, thus confirming its reinforcing effect. Reinforcement via PIBOMA addition was also observed for vulcanized rubbers in the viscoelastic region and the rubbery plateau, i.e. from −20 to 180 °C, by dynamic mechanical thermal analysis. Notably, while at temperatures above ~125 °C, ultra-high-molecular-weight polyethylene (UHMWPE) rapidly loses its ability to provide reinforcement due to softening/melting, all PIBOMA resins maintained their ability to reinforce rubber matrix up to 180 °C. For rubber compositions containing 20 phr of PIBOMA, both tensile strength and elongation at break decreased with increasing PIBOMA molecular weight. In summary, PIBOMA, with its outstanding high Tg among known poly(methacrylates), may be used in the preparation of advanced high-stiffness rubber compositions, where it provides reinforcement above 120 °C and gives properties appropriate for a range of applications.
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