Here we report a new type of n-type flexible film with a double-layer structure fabricated by hybridizing an n-type inorganic thermoelectric material, bismuth selenide (Bi2Se3), and an ordinary insulating polymer, poly(vinyl alcohol) (PVA). Flake-shaped Bi2Se3 nanoparticles (Bi2Se3 nanoflakes) modified with/without gold (Au) nanoparticles were distributed in the one side of PVA film with the particular arrangement, and the hybrid film showed a high Seebeck coefficient (−91 µV/K at room temperature) as an n-type flexible material. Our method is expected to be used for the design of flexible functional devices such as flexible thermoelectric modules.

Due to the lack of an effective and noninvasive screening tool, the early diagnosis of colorectal cancer (CRC) is currently difficult. For the early diagnosis of CRC, we have developed Fe3O4-Dye800-single chain fragment variable (ScFv)egfr/vegfr nanoprobes. ScFvegfr/vegfr (ScFv2) conjugated onto Fe3O4 nanoprobes efficiently recognized CRC tumors in vitro and in vivo. Near-infrared fluorescence imaging modalities such as Dye800 were utilized simultaneously with magnetic resonance to enhance detection efficiency. Fe3O4-Dye800-ScFv2 successfully detected tiny CRC tumors; the synergistic ScFv2 successfully enhanced CRC targeting. Thus, Fe3O4-Dye800-ScFv2 nanoprobes may represent a new molecular imaging strategy for the early detection of CRC.

Palladium (Pd) and gold (Au) nanoparticles (NPs) hybridized on two types of carbon supports, graphene and granular activated carbon (GAC), were shown to be promising catalysts for the sustainable hydrodehalogenation of aqueous trichloroethylene (TCE). These catalysts are capable of degrading TCE more rapidly than commercial Pd-on-GAC catalysts. The catalysts were synthesized at room temperature without the use of any environmentally unfriendly chemicals. Pd was chosen for its catalytic potency to break down TCE, while Au acts as a strong promoter of the catalytic activity of Pd. The results indicate that both graphene and GAC are favorable supports for the NPs due to high surface-to-volume ratios, unique surface properties, and the prevention of NP aggregation. The properties of NP catalysts were characterized using electron microscopy and spectroscopy techniques. The TCE degradation results indicate that the GAC-supported catalysts have a higher rate of TCE removal than the commercial Pd-on-GAC catalyst, and the degradation rate is greatly increased when using graphene-supported samples.

Seeking a latent-crosslinkable, mechanically flexible, fully thermoplastic shape memory polymer, we have developed a simple but effective macromolecular design that includes pendent crosslinking sites via the chain extender of a polyurethane architecture bearing semicrystalline poly(ε-caprolactone) (PCL) soft segments. This new composition was used to prepare fibrous mats by electrospinning and films by solvent casting, each containing thermal initiators for chemical crosslinking. The one-step synthesis strategy proved successful, and the crosslinking sites within PCL segments resulted in two-way (reversible) shape memory: repeatable elongation (cooling) and contraction (heating) under constant tensile stress. Being fully characterized, the crosslinked fiber mats revealed promising one-way and two-way (reversible) shape memory phenomena, with lower storage moduli though, compared to uncrosslinked films. We observed for both fibrous mats and films that increasing the applied tensile stress led to greater crystallization-induced elongation upon cooling as well as smaller strain hysteresis, particularly for covalently crosslinked samples. Relevant to medical applications, the materials were observed to feature unique, two-stage enzymatic degradation that was sensitive to differences in crystallinity and microstructure among samples.

High-entropy alloys (HEAs) with multiple principal elements open up a practically infinite space for designing novel materials. Probing this huge material universe requires the use of combinatorial and high-throughput synthesis and processing methods. Here, we present and discuss four different combinatorial experimental methods that have been used to accelerate the development of novel HEAs, namely, rapid alloy prototyping, diffusion-multiples, laser additive manufacturing, and combinatorial co-deposition of thin-film materials libraries. While the first three approaches are bulk methods which allow for downstream processing and microstructure adaptation, the latter technique is a thin-film method capable of efficiently synthesizing wider ranges of composition and using high-throughput measurement techniques to characterize their structure and properties. Additional coupling of these high-throughput experimental methodologies with theoretical guidance regarding specific target features such as phase (meta)stability allows for effective screening of novel HEAs with beneficial property profiles.

Refractory high-entropy alloys (RHEAs) have recently attracted much attention, primarily due to their mechanical properties at elevated temperatures. However, the equilibrium phase-stability of these alloy systems is not well established. The present investigation focuses on the phase stability of Al0.5NbTa0.8Ti1.5V0.2Zr RHEA at temperatures ranging from 600 to 1200 °C. The detailed phase characterization involves coupling of scanning electron microscopy, transmission electron microscopy, and atom probe tomography. The stable phases present at these temperatures are (i) 1200 °C—body-centered cubic (BCC) matrix with nano-B2 precipitates; (ii) 1000 °C and 800 °C—a BCC matrix phase with Al–Zr rich hexagonal closed packed intermetallic precipitates and, (iii) 600 °C—a BCC + B2 microstructure, comprising a continuous BCC matrix with discrete B2 precipitates. These results highlight the substantial changes in phase stability as a function of temperature in RHEAs, and high-entropy alloys in general, and also the importance of accounting for these changes especially while designing alloys for high temperature applications.

The objective of the study was to modify the external surface of commercially produced polyethylene (PE) tubes made by Balton, Poland, to improve their hydrophilic properties. The process was conducted in a new dielectric barrier discharge reactor. The carrier gases were argon and air, whereas carbon dioxide and hydrogen were the doping gases. The influence of the gas composition in the plasma chamber on the surface free energy (SFE) of PE tubes was investigated. For the gas composition 50 vol% of Ar + 50 vol% of CO2, the highest value of the SFE (53.4 mJ/m2) was obtained. It means an increase in SFE approx. 17% as compared to the unmodified sample (46.0 mJ/m2). Fourier-transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) results indicates that on the surface of the tubes, carboxyl, carbonyl, and hydroxyl groups were formed. Those oxygen-containing groups could be responsible for the increase of the hydrophilic effect. The O/C ratio on the surface, measured by the X-ray photoelectron spectroscopy method, was three times higher in the case of the modified samples than in those which were not subjected to plasma treatment.

High-entropy alloys (HEAs) are receiving considerable attention since last decade because of their ability to give excellent strength with reasonably good elongation during fracture. The mechanical alloying followed by sintering is one of the routes for fabrication; however, there are limited reports on sintering mechanisms of HEA powders. The present investigation studies sintering mechanisms of CoCrFeNi alloy powders in as-milled and annealed conditions using dilatometer experiments. The annealed powder shows slower densification behavior and higher activation energy of sintering, compared to the as-milled powder. Diffusion coefficients were analyzed through sintering models and compared with literature data. The as-milled powder was found to exhibit mixed response, i.e., the grain boundary diffusion seems to be dominating initially due to a large grain boundary fraction but volume diffusion (VD) also contributes significantly, due to high defect concentration and metastable phases. VD was found to be the dominating mechanism during sintering of single phase, stable annealed powder.

The ability to manipulate matter on the nanometer length scale is an important scientific goal, and the progress in the field of colloidal nanocrystal (NC) growth in the past decades has opened avenue for controlled synthesis of nanoscale materials with many unique physical properties that could enhance existing technologies or give rise to entirely new technologic applications. At the center of the progress is ever-increasing understanding on molecular interactions within colloidal synthesis, in which nucleation and growth each plays a critical role in the control of size, shape, morphology, and structure of NCs. Semiconductor NCs in quantum confinement regime, referred to as quantum dots (QDs), highlight the importance of such control over geometric parameters, since QDs exhibit size- and shape-dependent optical properties. In this paper, we demonstrate important aspects that govern QDs growth in the context of (i) precursor conversion chemistry, and (ii) intermediate species including molecular complex and clusters. Advances in understanding the growth chemistry of QDs have proved the significance of how precursors decompose and produce intermediate species. We review recent progress in regards to the synthetic chemistry of colloidal QDs and discuss our perspective on challenges and promises in the controlled large-scale synthesis of QDs.

Gold nanoparticles (GNPs) of ~8 nm in diameter were used for the detection of organochlorine endosulfan pesticide (ESP) as colorimetric sensor and the design of GNP-based chemical sensor for its quantitative estimation has also been proposed. The original wine red color of GNPs changes into various shades of blue after the addition of different concentrations of ESP solutions. A GNP-based sensing electrode has been used for designing of ESP detection chemical sensor at ambient temperature. The response and sensitivity of ESP sensor parameters are obtained from their recovery curves of the change in resistance versus time.

N-doped ordered mesoporous carbon (N-OMC) has been one of the most promising choices as the electrode for supercapacitors due to its large surface area and uniform mesoporous structure. However, there is still a big challenge to prepare N-OMC using a relatively simple method. Here, a straightforward preparation of N-OMC was reported in which the precursor zeoliticimidazolate framework was in situ grown in the SBA-15 template by a fast, solvent-free, and atom economic solid–solid grinding strategy. After pyrolysis and removing of the template, the N-OMC was obtained with ordered mesoporous structure, rich oxygen and nitrogen, and a large specific surface area of 1004 m2/g. As the electrode material for supercapacitors, N-OMC displayed an excellent specific capacitance of 228 F/g at 0.2 A/g and superb charge/discharge cycling stability, which is promising for high-performance energy storage. This solid–solid grinding strategy may offer a low-cost and scalable method to produce high-performance N-OMC for the electrode from the zeoliticimidazolate framework.

We investigate the photostability of a set of organic semiconductor blends comprising a conjugated polymer as the donor and a fullerene as the acceptor using electron spin resonance (ESR). In the absence of oxygen, all blends show excellent stability. Even after several hundred hours of exposure to solar or UV radiation, the ESR spectra and the recombination of photoinduced charges recorded at low temperature are found to be unchanged. By contrast, the presence of oxygen leads to a fast light-induced degradation rendering the ability of the donor/acceptor system to form photoinduced charge carriers. Our findings suggest that conjugated polymer–fullerene blends exhibit very good photostability and that oxygen needs to be excluded in optoelectronic applications. Our findings also suggest that at low temperature, a universal recombination process of long-lived photoinduced charges is active, which does not depend on the electronic structure or the morphology of the investigated materials.

Thin hole transport layers are important elements in organic semiconductor-based devices. Metal oxides are an encouraging material class for this purpose, as they may provide sufficient hole conduction in combination with excellent electron blocking properties. Both, long-term device stability, which may often be limited by the thermal stability of interfaces, and higher temperature processing steps, benefit strongly from the existence of thermally stable metal oxide interlayers. Provided that thermally stable electrodes can be fashioned, the stability of organic active layers—for example, in organic field effect transistors, light emitting diodes, or photovoltaic (OPV) devices can be investigated. Here, we apply this concept and report about the study of hole mobility (µh) in single-carrier-hole-only devices in dependence of thermal annealing up to the above the actual melting temperature of regio-regular poly(3-hexylthiophene-2,5-diyl) (P3HT).

Nanomaterials have been proposed as key components in biosensing, imaging, and drug delivery since they offer distinctive advantages over conventional approaches. The unique chemical and physical properties of graphene make it possible to functionalize and develop protein transducers, therapeutic delivery vehicles, and microbial diagnostics. In this study, we evaluate reduced graphene oxide as a potential nanomaterial for quantification of microRNAs including their structural differentiation in vitro in solution and inside intact cells. Our results provide evidence for the potential use of graphene nanomaterials as a platform for developing devices that can be used for microRNA quantitation as biomarkers for clinical applications.

Metal–graphene composites are sought after for various applications. A hybrid light-weight foam of nickel (Ni) and reduced graphene oxide (rGO), called Ni-rGO, is reported here for small molecule oxidations and thereby their sensing. Methanol oxidation and non-enzymatic glucose sensing are attempted with the Ni-rGO foam via electrocatalytically, and an enhanced methanol oxidation current density of 4.81 mA/cm2 is achieved, which is ~1.7 times higher than that of bare Ni foam. In glucose oxidation, the Ni-rGO electrode shows a better sensitivity over bare Ni foam electrode where it could detect glucose linearly over a concentration range of 10 µM to 4.5 mM with a very low detection limit of 3.6 µM. This work demonstrates the synergistic effects of metal and graphene in oxidative processes, and also shows the feasibility of scalable metal–graphene composite inks development for small molecule printable sensors and fuel cell catalysts.

Fullerene derivatives have been ubiquitous as an electron-accepting material in organic photovoltaic solar cells (OSCs). We consider whether and why traces of PCBM oxidation products should be seen as electronic defects impairing the performance of OSCs. Thin PCBM deposits were first illuminated under ambient air for a few minutes, thus revealing the extraordinary easiness of oxidizing PCBM. The charge transfer in polymer:PCBMox bulk heterojunctions was then studied. As a result of a few minutes of PCBM photooxidation, the electron transfer from the polymer to two types of PCBMox species was shown to occur at the expense of the transfer to pristine PCBM. Such modifications to the molecular structure of PCBM and to the charge transfer at the nanoscale were finally correlated with a dramatic loss in the device’s photovoltaic performance at the macroscale. This study clearly indicates the need to integrate photooxidation-resistant electron-accepting materials into OSCs to extend their lifetime.