Substrate Resistance Research Articles

Laser-Induced Graphene Composites as Multifunctional Surfaces.

Laser-induced graphene (LIG) is a platform material for numerous applications. Despite its ease in synthesis, LIG's potential for use in some applications is limited by its robustness on substrates. Here, using a simple infiltration method, we develop LIG composites (LIGCs) with physical properties that are engineered on various substrate materials. The physical properties include surface properties such as superhydrophobicity and antibiofouling; the LIGCs are useful in antibacterial applications and Joule-heating applications and as resistive memory device substrates.

Piezoresistive effect in embedded thick-film resistors

Purpose Nowadays, using of material properties for monitoring of phenomena occurring in the surrounding environment is very desirable. Taking into account the dynamic development of Internet of Things and the technological development of printed electronics, research into the using of printed electronic components for sensor applications can be one of the most prominent directions of searching for new innovative solutions. Among others, it is possible to apply them to produce the strain gauges, as well as for construction of advanced sensors for medical applications. The goal of this paper is to present the possibilities and using different constructions of embedded polymer thick-film resistors as the sensors of tension or strain. Design/methodology/approach The investigations were based on the polymer thick-film resistors made of carbon or carbon–silver inks printed on copper pads made on FR-4 material on two sides. The longitudinal samples laminated with resin-coated copper foil material and without lamination were bent on a strength machine. During the tests, the resistors depending on their placement were stretched or compressed. Some of the samples were also tested under high pressure. Under the influence of applied stresses, there was a reversible change in electrical resistance, which was monitored. Findings The study showed that the polymer thick-film resistors are characterized by a measurable piezoresistive effect. By analyzing the value of the observed resistance changes, a magnitude of strain or pressure can be worked out. During the bending, the piezoresistive effect depends on the location and orientation of the resistor. After stopping of the mechanical strains, the electrical resistance of the resistive elements does not return exactly to the initial value. This is probably related to the substrate material and the resistive paste composition. The results are very promising and further research will be done. Originality/value The results provided information about the piezoresistive effect of polymer thick-film resistors printed on the deformable substrate which could be interesting for engineers involved in printed sensor development dedicated for different fields of application. This phenomenon can be used to manufacturing cheap and uncomplicated sensors to monitor deformation. There are several aspects to be solved, but with the use of new types of resistive pastes and substrates, there is a potential possibility of using such resistors as sensors.

Characterisation of AMS H35 HV-CMOS monolithic active pixel sensor prototypes for HEP applications

Monolithic Active Pixel Sensors (MAPS) produced in High Voltage CMOS (HV-CMOS) technology are being considered for High Energy Physics applications due to the ease of production and the reduced costs. Such technology is especially appealing when large areas to be covered and material budget are concerned. This is the case of the outermost pixel layers of the future ATLAS tracking detector for the High Luminosity LHC. For experiments at hadron colliders, radiation hardness is a key requirement which is not fulfilled by standard CMOS sensor designs that collect charge by diffusion. This issue has been addressed by depleted active pixel sensors in which electronics are embedded into a large deep implantation ensuring uniform charge collection by drift. Very first small prototypes of hybrid depleted active pixel sensors have already shown a radiation hardness compatible with the ATLAS requirements. Nevertheless, to compete with the present hybrid solutions a further reduction in costs achievable by a fully monolithic design is desirable. The H35DEMO is a large electrode full reticle demonstrator chip produced in AMS 350 nm HV-CMOS technology by the collaboration of Karlsruher Institut für Technologie (KIT), Institut de F'isica d'Altes Energies (IFAE), University of Liverpool and University of Geneva. It includes two large monolithic pixel matrices which can be operated standalone. One of these two matrices was characterised at beam test before and after irradiation with protons and neutrons. Results demonstrated the feasibility of producing radiation hard large area fully monolithic pixel sensors in HV-CMOS technology. H35DEMO chips with a substrate resistivity of 200 Ωcm} irradiated with neutrons showed a radiation hardness up to a fluence of 1×1015 neq/cm2 with a hit efficiency of about 99% and a noise occupancy lower than 10-6 hits in a LHC bunch crossing of 25 ns at 150 V.

PROPOSED TRAVELLING WAVE TUNNETT AMPLIFIER AND OSCILLATOR FOR AIRBORNE RADARS

Two travelling wave TUNNETT diode structures are propoposed. The first one is a distributed TUNNETT which is proposed in order to overcome the inherent limitations on the power output of the discrete TUNNETT structure. ItAs shown that this structure can be used as resonant lengths of transmission line in order to tune out the diode depletion layer capacitance. Therefore, the distributed structure can have a much higher impedance, a larger area and a higher output power than the discrete one and will be much easier to match. It is found that a relatively high substrate resistivity gives better performance. It is also found that for a given substrate resistivity there is an optimum value of substrate thickness. Design graphs for the proposed device are presented. An output power of about 12 watts has been optained at a frequency of 30 GHz which is an important result. The second proposed structure is a multistream TUNNETT structure which is based on the space charge interactions of electron streaming layers. Each layer has a different average velocity due to a properly chosen concentration gradiant along the direction transverse to the motion of electrons. A numerical analysis is used to determine the gain of the proposed structure when it is used as a travelling wave amplifier. It is found that this gain decreases with increasing the diode thickness and slightly increases with the operating frequency in the frequency range considered. The proposed devices suffer no transit-time limitations sotheir bandwidth is much wider than that of a discrete TUNNETT. The possible applications of the proposed devices in airborne radars are indicated.

Non-Metallic Films Electroplating on the Low-Conductivity Substrates: The Conscious Selection of Conditions Using Ni(OH)2 Deposition as an Example

Mathematical modelling was used to study the influence of different parameters on the distribution of current density during electrodeposition of low-conductivity films on high-resistance substrates (FTO, ITO etc.). Experimental data were used to model the deposition of non-conductive Ni(OH)2 film onto FTO glass. The influence of substrate resistance, polarization resistance, electrolyte concentration, and other parameters on the current density distribution over the electrode surface was analyzed. The analysis of modelling results revealed that the fundamental differences in the current density distribution during deposition of coatings in electroplating and deposition of low-conductivity films are due to the high resistance of the substrate in the latter case. It was found that the impact on the uniformity of the current density distribution was decreasing in the series “substrate resistivity – polarization resistance – electrolyte conductivity”. The results of the conducted modelling allowed formulating recommendations for electrochemical deposition of low-conductivity films uniformly distributed over the surface of the substrate with low conductivity. In this case, the use of diluted electrolytes was justified. The results of galvanostatic deposition of Ni(OH)2 films onto FTO glass (7.5 Ω/□, 2 × 2 cm) from 1М and 0.01М solutions of Ni(NO3)2 and the subsequent colorization proved the modelling results experimentally. The width of Ni(OH)2 film deposited from 1M solution was less than 1mm, while the coating was absent on the rest of the surface. Deposition from 0.01 solution resulted in a uniform film with complete coverage of the working electrode area.

The Formation Mechanism of Nondefective Silicon Micropatterns Fabricated by Scratching Assisted Electrochemical Etching

Fabrication of nondefective silicon microstructures at specific region is of great importance but challenging, which is promising to boost the performance of microsensors, micro energy storage devices, and microfluidic devices. A low-cost approach to fabricate nondefective silicon microstructures based on scratching assisted electrochemical etching has been proposed. Shallow patterns together with silicon amorphous and defects layer were scratched by the diamond tip. The scratched area was utilized as sacrificial layer in the electrochemical etching process and removed rapidly. The introduction of electrochemical etching would change the distribution of holes in the groove area and substrate, thus the formation and morphology of the nondefective silicon structures are different. The influences of etching voltage, scratching load, etching duration, resistivity and crystal orientation of substrates on the silicon microstructures were discussed systematically. The depth, width and cross section shape of the silicon microstructures change with etching duration, voltage polarity and resistivity. But the crystal orientation has little effect on the width and depth of silicon microstructures. Nondefective silicon microstructures array with different pitch and height can be fabricated in specific location by the scratch assisted electrochemical etching approach, which can be used in high performance micro devices.

A Substrate Model for On-Chip Tapered Spiral Inductors With Forward and Reverse Excitations

In this brief, closed-form analytical expressions are obtained to accurately calculate the oxide and substrate (both lateral/vertical) capacitances of the $\pi $ -equivalent circuit model for on-chip tapered spiral inductors. A lateral RC substrate network using the above-mentioned expressions is shown to significantly improve the model accuracy, especially with lower substrate resistivities. Furthermore, improvement in Qmax with reverse excitation in tapered spirals is also accurately predicted by the proposed model. The accuracy of the proposed model is validated till 15 GHz using several inductor geometries across process parameters suitable for the design of RF circuits. Excellent agreement is observed between the model, electromagnetic simulations, and measurements.

Comparative Investigation on Bias Dependent RF Performance of SOI Substrates

In this work, direct current (DC) bias effects on radio frequency (RF) performance of three types of RF silicon-on-insulator (RF-SOI) substrates are comparatively investigated by using coplanar waveguide (CPW) lines. It is demonstrated that the loss and harmonic distortion of CPW line on high resistivity silicon-on-insulator (HR-SOI) substrate are more sensitive to variations of DC bias. This is attributed to the parasitic nonlinear capacitance and conductance in the parasitic surface conduction (PSC) layer. In comparison, the influence of DC bias on the RF performance of trap-rich silicon-on-insulator (TR-SOI) substrate can be negligible due to the trap-rich layer which can get rid of the PSC by trapping free carriers inside the substrate. Bias effects on the RF performance of two types of TR-SOI substrates with different high resistivity substrate are also compared. The results show that the RF characteristics of TR-SOI #2 (TR2) is more independent with respect to the applied bias than that of TR-SOI #1 (TR1). This stems from the smaller parasitic effects and increased effective resistivity.

Study of the depletion depth in a frontside biased CMOS pixel sensors

Depletion of the sensitive volume for semiconductor based detectors is a key to achieve high performance. It is for instance required for charged particle detection in highly radiative environment and for X-ray spectroscopy.PIPPER-2 is a CMOS pixel sensor featuring an architecture that allows the application of the reverse bias of the pn junction from the frontside (cathode), on the electronic side, without process modification. Biasing voltages up to 45 V have been applied to sensor prototypes fabricated on two different high resistivity substrates: a thin epitaxial layer (1 kΩ cm) and a 40 μm thick bulk substrate (600 Ω cm).Calculations from a simplified analytical model and 3D-TCAD simulations were conducted to predict the evolution of the depletion depth with the bias voltage. These expectations were compared to measurements of PIPPER-2 illuminated with two X-ray energies.We conclude that the frontside biasing method allows the full-depletion of the thin epitaxial layer. In contrast, depletion of the bulk substrate reaches about half-depth but X-rays are still detected over the full depth.

FK506 Resistance of Saccharomyces cerevisiae Pdr5 and Candida albicans Cdr1 Involves Mutations in the Transmembrane Domains and Extracellular Loops.

The 23-membered-ring macrolide tacrolimus, a commonly used immunosuppressant, also known as FK506, is a broad-spectrum inhibitor and an efflux pump substrate of pleiotropic drug resistance (PDR) ATP-binding cassette (ABC) transporters. Little, however, is known about the molecular mechanism by which FK506 inhibits PDR transporter drug efflux. Thus, to obtain further insights we searched for FK506-resistant mutants of Saccharomyces cerevisiae cells overexpressing either the endogenous multidrug efflux pump Pdr5 or its Candida albicans orthologue, Cdr1. A simple but powerful screen gave 69 FK506-resistant mutants with, between them, 72 mutations in either Pdr5 or Cdr1. Twenty mutations were in just three Pdr5/Cdr1 equivalent amino acid positions, T550/T540 and T552/S542 of extracellular loop 1 (EL1) and A723/A713 of EL3. Sixty of the 72 mutations were either in the ELs or the extracellular halves of individual transmembrane spans (TMSs), while 11 mutations were found near the center of individual TMSs, mostly in predicted TMS-TMS contact points, and only two mutations were in the cytosolic nucleotide-binding domains of Pdr5. We propose that FK506 inhibits Pdr5 and Cdr1 drug efflux by slowing transporter opening and/or substrate release, and that FK506 resistance of Pdr5/Cdr1 drug efflux is achieved by modifying critical intramolecular contact points that, when mutated, enable the cotransport of FK506 with other pump substrates. This may also explain why the 35 Cdr1 mutations that caused FK506 insensitivity of fluconazole efflux differed from the 13 Cdr1 mutations that caused FK506 insensitivity of cycloheximide efflux.

Ultrahigh position sensitivity and fast optical relaxation time of lateral photovoltaic effect in Sb2Se3/p-Si junctions.

A large lateral photovoltaic (LPV) effect with good linearity and fast response time is necessary for developing high-performance position-sensitive detectors (PSD). In this paper, we investigated the influence of the resistance of Sb2Se3 film and the Si on the LPV properties of the Sb2Se3/p-Si junctions. The LPV exhibits a linear dependence on the laser spot position, with a maximum position sensitivity as high as 448 mV/mm. The optical relaxation time of the LPV was about 4.98 μs, which was due to the formation of the inversion layer at the Sb2Se3/p-Si interface. Our results revealed that the high resistivity of Sb2Se3 film facilitate the LPV and confirmed the resistivity of Si substrate play a key role in the LPV properties. The giant position sensitivity and fast relaxation times of the LPV suggest that the Sb2Se3/p-Si junction is a promising candidate for a wide range of optoelectronic device applications.

Field emission properties of carbon nitride synthesized by microwave plasma chemical vapor deposition

Crystalline carbon nitride is expected to be an emitter with a long lifetime and high emission stability, because it is composed of carbon and nitrogen with high oxidation resistance and its sharp shape facilitates the occurrence of electron emission. The purpose of this paper is to clarify the field emission properties of crystalline carbon nitride. We studied the improvements in the field emission properties of carbon nitride after surface treatments. The carbon nitride was synthesized using microwave plasma chemical vapor deposition from a CH4-N2 gas system. Si substrates with different electrical properties (p- and n-type of 0.01 and 1500 Ω, respectively) were used. The carbon nitride on the 0.01 Ω n-type substrate showed the highest current density of approximately 0.25 mA/cm2. The maximum current densities of the carbon nitride on the n-type or p-type substrates were higher than those of the undoped type by decreasing the resistivity of the substrate. The threshold field (emission current observed in the minimum electric field) of the carbon nitride on n-type substrates was decreased by decreasing the substrate resistance. In the case of Au-coated deposits on an n-type Si substrate of 0.01 Ω, a threshold field was observed at approximately 1 V/μm. In addition, the electric field emission current density at 20 V/μm was 0.83 mA/cm2. The ultra-thin coatings of Au on the carbon nitride were effective in decreasing the threshold field and increasing the maximum current density. The Fowler-Nordheim plots of the carbon nitride with or without Au coatings formed a straight line, indicating that the Fowler-Nordheim theory perfectly fit the field emission behaviors of samples.

Test beam measurement of ams H35 HV-CMOS capacitively coupled pixel sensor prototypes with high-resistivity substrate

In the context of the studies of the ATLAS High Luminosity LHC programme, radiation tolerant pixel detectors in CMOS technologies are investigated. To evaluate the effects of substrate resistivity on CMOS sensor performance, the H35DEMO demonstrator, containing different diode and amplifier designs, was produced in ams H35 HV-CMOS technology using four different substrate resistivities spanning from 80-1000 ohm cm-1. A glueing process using a high-precision flip-chip machine was developed in order to capacitively couple the sensors to FE-I4 Readout ASIC using a thin layer of epoxy glue with good uniformity over a large surface. The resulting assemblies were measured in beam test at the Fermilab Test Beam Facilities with 120 GeV protons and CERN SPS H8 beamline using 180 GeV pions. The in-time efficiency and tracking properties measured for the different sensor types are shown to be compatible with the ATLAS ITk requirements for its pixel sensors.

Evaluation of Ni-Cr-P coatings electrodeposited on low carbon steel bipolar plates for polymer electrolyte membrane fuel cell

Polymer electrolyte membrane fuel cell (PEMFC) stacks suffer from the high cost and low volumetric energy of non-porous graphite bipolar plates. To resolve this problem, a bilayer coating consisting of Ni and Ni–Cr–P is deposited on AISI 1020 low-carbon steel using pulse electrodeposition. Ni/Ni–Cr–P-coated AISI 1020 is evaluated as a bipolar plate material for PEMFCs. Ni/Ni–Cr–P-coated substrates exhibit better corrosion resistance in both cathodic (air-purging) and anodic (H2-purging) environment than the bare AISI 1020 substrate and lower interfacial contact resistance (ICR) than bare AISI 1020 and stainless steel. Further, it is expected to show better water management as the Ni/Ni–Cr–P coating is more hydrophobic than the bare substrate. Preliminary studies show that Ni/Ni–Cr–P-coated AISI 1020 plate can be a suitable candidate for replacing graphite as the bipolar plate of PEMFCs.

Comprehensive electrical loss analysis of monolithic interconnected multi‐segment laser power converters

AbstractA method for distributed electrical modeling of complete photovoltaic monolithic interconnected modules (MIMs) with complex geometrical and electrical features is developed and applied to study electrical power losses of a six‐segment GaAs‐based MIM laser power converter (LPC). The model considers spatial dependence of resistive and recombination losses of all epitaxial layers and explicitly takes into account perimeter recombination and the photo‐induced leakage current through the semi‐insulating GaAs substrate. The investigated specimen was fully parametrized to obtain the model's input parameters which were verified by a comparison of a variety of simulated and measured specimen's electrical characteristics. Based on simulations, we show that distributed series resistance effects, mainly caused by Joule heating in the lateral conduction layer (LCL), limit the efficiency of MIM LPCs under a high irradiance illumination, whereas for a low irradiance illumination perimeter recombination is identified as the limiting factor. Additionally, photo‐induced conductivity leads to a reciprocal relationship between irradiance and substrate resistivity, which results in a parasitic shunting between segments and reduces the device efficiency. We present mitigation strategies for the outlined major loss mechanisms and propose a thin‐film cell employing a metal back mirror that exploits photon recycling and mitigates LCL losses. With such MIM LPC design, conversion efficiencies above 60% can be reached for a broad irradiance range.

Gut Microbiota-Mediated Bile Acid Transformations Alter the Cellular Response to Multidrug Resistant Transporter Substrates in Vitro: Focus on P-glycoprotein.

Pharmacokinetic research at the host-microbe interface has been primarily directed toward effects on drug metabolism, with fewer investigations considering the absorption process. We previously demonstrated that the transcriptional expression of genes encoding intestinal transporters involved in lipid translocation are altered in germ-free and conventionalized mice possessing distinct bile acid signatures. It was consequently hypothesized that microbial bile acid metabolism, which is the deconjugation and dehydroxylation of the bile acid steroid nucleus by gut bacteria, may impact upon drug transporter expression and/or activity and potentially alter drug disposition. Using a panel of three human intestinal cell lines (Caco-2, T84, and HT-29) that differ in basal transporter expression level, bile acid conjugation-, and hydroxylation-status was shown to influence the transcription of genes encoding several major influx and efflux transporter proteins. We further investigated if these effects on transporter mRNA would translate to altered drug disposition and activity. The results demonstrated that the conjugation and hydroxylation status of the bile acid steroid nucleus can influence the cellular response to multidrug resistance (MDR) substrates, a finding that did not directly correlate with directionality of gene or protein expression. In particular, we noted that the cytotoxicity of cyclosporine A was significantly augmented in the presence of the unconjugated bile acids deoxycholic acid (DCA) and chenodeoxycholic acid (CDCA) in P-gp positive cell lines, as compared to their taurine/glycine-conjugated counterparts, implicating P-gp in the molecular response. Overall this work identifies a novel mechanism by which gut microbial metabolites may influence drug accumulation and suggests a potential role for the microbial bile acid-deconjugating enzyme bile salt hydrolase (BSH) in ameliorating multidrug resistance through the generation of bile acid species with the capacity to access and inhibit P-gp ATPase. The physicochemical property of nonionization is suggested to underpin the preferential ability of unconjugated bile acids to attenuate the efflux of P-gp substrates and to sensitize tumorigenic cells to cytotoxic therapeutics in vitro. This work provides new impetus to investigate whether perturbation of the gut microbiota, and thereby the bile acid component of the intestinal metabolome, could alter drug pharmacokinetics in vivo. These findings may additionally contribute to the development of less toxic P-gp modulators, which could overcome MDR.

Fabrication and RF Property Evaluation of High-Resistivity Si Interposer for 2.5-D/3-D Heterogeneous Integration of RF Devices

In this paper, a high-resistivity silicon (HR-Si) interposer integrated with through-silicon via (TSV) electrically grounded coplanar waveguide (CPW) line is presented for 2.5-D/3-D heterogeneous integration of radio frequency (RF) microelectronics devices. In addition, design of TSV interconnection composed of two coaxial ladder-hollow-annular Cu (copper) TSVs of different diameters is utilized to maintain a sufficient freedom for strict standard cleaning to avoid Si resistivity degradation. The formation of the coaxial ladder TSV structure is more beneficial to the subsequent plating process because it reduces the aspect ratio of TSV vias. Hollow-annular Cu TSV is manufactured in order to reduce the problem of mismatch in coefficient of thermal expansion among TSV’s constituent materials. A layer of Au (aurum) film is utilized to passivate the exposed Cu surface of Si interposer. Au is widely used in III–V groups’ devices because of the good compatibility with photonic integrated circuits, conductivity, and corrosion resistance. HR-Si interposer with TSV grounded CPW line and test structure is fabricated and characterized. With the monitoring test results, it can be found that it changes little in the resistivity of Si substrate, though the whole process, which is a basic requirement for RF performance. RF property test results show that the insertion loss is about −0.20 dB/mm at 10 GHz for the presented TSV grounded CPW line and −0.02 dB per TSV. These test results are better than the traditional design. To verify its applicability to 2.5-D/3-D heterogeneous integration, RF microelectronics die is assembled on TSV interposer and tested, and the test results prove that it works properly.

Social thermoregulation and socio-physiological effect in the subterranean Mashona mole-rat (Fukomys darlingi)

A strict underground style of life is one of the greatest challenges for mammals partly due to the high energetic cost of obtaining food by digging through a mechanically resistant substrate. Any energy saving adaptation, for example the effect of social thermoregulation, is thus very important for subterranean mammals. It has also been suggested that social mammals may suffer from “isolation stress” if measured alone, because the presence of other family member(s) may decrease the stress levels and thus their metabolic rates. This phenomenon known as a socio-physiological effect should be conspicuous when the metabolism of huddling individuals is measured within a species΄ thermoneutral zone (TNZ), where no energetic costs for body warming or cooling exist. In our study, we measured the resting metabolic rates of a social species of African mole-rat, the Mashona mole-rat (Fukomys darlingi), in individuals, pairs and groups of three to eight individuals. Measurements were carried out at ambient temperature below the species’ TNZ (20 °C) to test the effect of social thermoregulation and at a temperature within the species’ TNZ (30 °C) to test the socio-physiological effect. In pairs, the Mashona mole-rat saved 25% of its individual energetic expenses at the temperature below the TNZ. With increasing group size, energetic savings rose up to four animals, but no savings were found in larger groups. At the temperature within the TNZ, mole-rats saved 10% of individual energetic expenses in pairs, but the difference was not significant. Also, no energetic savings were found in larger groups within the TNZ. Our results on thermoregulatory savings in the TNZ are in contrast with extremely high energetic savings found by other authors in different mole-rat species.

Neonicotinoid insecticides are potential substrates of the multixenobiotic resistance (MXR) mechanism in the non-target invertebrate, Dreissena sp.

Mussels are among the most frequently used invertebrate animals in aquatic toxicology to detect toxic exposure in the environment. The presence and activity of a cellular defence system, the multixenobiotic resistance (MXR) mechanism, was also established in these organisms.In isolated gill tissues of dreissenid mussels (D. bugensis) the MXR activity was assayed after treatment by commercially available insecticides (formulated products) which contain neonicotinoids as their active ingredients: Actara (thiamethoxam), Apacs (clothianidin), Calypso (thiacloprid) and Kohinor (imidacloprid), respectively. While applying the accumulation assay method, 0.5 μM rhodamine B was used as model substrate and 20 μM verapamil as model inhibitor of the MXR mechanism.In acute (in vitro) experiments when isolated gills were co-incubated in graded concentrations of insecticides and rhodamine B simultaneously, Calypso and Kohinor treatment resulted increasing rhodamine accumulation. Chemical analysis of gills in vitro incubated in insecticides demonstrated higher tissue concentrations of thiamethoxam, clothianidin and thiacloprid in the presence of verapamil suggesting that the active ingredients of Actara, Apacs and Calypso are potential substrates of the MXR mediated cellular efflux. In contrast, verapamil did significantly alter the accumulated imidacloprid concentrations in gills, suggesting that the active component of Kohinor is not transported by the MXR mechanism.Chronic (in vivo) exposures of the intact animals in lower, 1, 10 mg/L concentration of neonicotinoid products, resulted in a decreased level of both rhodamine accumulation and verapamil inhibition by the 12th–14th days of treatment. These results suggest an enhancement of MXR activity (chemostimulation), building up gradually in the animals exposed to Actara, Apacs and Kohinor, respectively.Neonicotinoid-type insecticides are generally considered as selective neurotoxins for insects, targeting the nicotinic type acetylcholine receptors (nAChRs) in their central nervous system. Our present results provide the first evidences that neonicotinoid insecticides are also able to alter the transmembrane transport mechanisms related to the MXR system.

Transparent Photocatalytic Thin Films on Flexible Polymer Substrates

Self-cleaning and/or photocatalytic films on polymer substrates have found numerous applications during the past decades. However, the common demand for high-temperature post synthesis treatment limits the application to temperature resistant substrates only. Herein, we prepared self-cleaning photocatalytic films on four thermosensitive polymeric substrates: polyvinyl chloride (PVC), polymethyl methacrylate (PMMA), and acryl coated polyester (PES) fabric (D2) with poly(vinylidene fluoride) (PVDF) containing lacquer (D1). TiO2 was prepared via a low-temperature sol-gel process using titanium(IV) isopropoxide and zirconium(IV) butoxide as precursors with various loading levels of Zr; 0, 5, 10, and 20 mol.%, and deposited on the substrates by using a SiO2 binder in form of thin films (ca. 200 nm thick) via dip-coating. The films were characterized by SEM, hardness test, UV-Vis, photothermal beam deflection spectroscopy, and IR spectroscopy, while photocatalytic activity was measured by the fluorescence-based method of the terephthalic acid probe and wetting by contact angle measurements. Films containing 10 mol.% of Zr showed the best compromise regarding photocatalytic activity and mechanical stability while from substrates point of view PVC performed the best, followed by PMMA, D1, and D2. The beneficial role of SiO2 binder was not only guaranteeing excellent mechanical stability, but also to prevent the D1 polymer from deterioration; the latter was found to be labile to long-term solar-light exposure due to degradation of the top PVDF layer.