Biocompatibility of titanium from the viewpoint of its surface.

Among metals, Ti and majority of its alloys exhibit excellent biocompatibility or tissue compatibility. Although their high corrosion resistance is a factor in the biocompatibility of Ti and Ti alloys, it is clear that other factors exist. In this review, the corrosion resistance and passive film of Ti are compared to those of other metallic biomaterials, and their band gap energies, Egs, are compared to discuss the role of Eg in the reactivity with living tissues. From the perspective of the material's surface, it is possible to explain the excellent biocompatibility of Ti by considering the following factors: Ti ions are immediately stabilized not to show toxicity if it is released to body fluids; good balance of positive and negative charges by the dissociation of surface hydroxyl groups on the passive film; low electrostatic force of the passive film inducing a natural adsorption of proteins maintaining their natural conformation; strong property as n-type semiconductor; lower band gap energy of the passive film on Ti generating optimal reactivity; and calcium phosphate formation is caused by this reactivity. The results suggest that due to the passive oxide film, the optimal balance between high corrosion resistance and appropriate reactivity of Ti is the predominate solution for the excellent biocompatibility of Ti.

Sensing Method Using Multiple Quantities for Diagnostic of Insulators in Different Ambient Conditions.

Insulators are one of the many components responsible for the reliability of electricity supply as part of transmission and distribution lines. Failure of the insulator can cause considerable economic problems that are much greater than the insulator cost. When the failure occurs on the transmission line, a large area can be without electricity supply or other transmission lines will be overloaded. Because of the consequences of the insulator's failure, diagnostics of the insulator plays a significant role in the reliability of the power supply. Basic diagnostic methods require experienced personnel, and inspection requires moving in the field. New diagnostic methods require online measurement if it is possible. Diagnostic by measuring the leakage current flowing on the surface of the insulator is well known. However, many other quantities can be used as a good tool for diagnostics of insulators. We present in this article results obtained on the investigated porcelain insulators that are one of the most used insulation materials for housing the insulator's core. Leakage current, dielectric loss factor, capacity, and electric charge are used as diagnostic quantities to investigate porcelain insulators in different pollution conditions and different ambient relative humidity. Pollution and humidity are the main factors that decrease the insulator´s electric strength and reliability.

Antimicrobial Properties of TiO2 Microparticles Coated with Ca- and Cu-Based Composite Layers.

The ability of TiO2 to generate reactive oxygen species under UV radiation makes it an efficient candidate in antimicrobial studies. In this context, the preparation of TiO2 microparticles coated with Ca- and Cu-based composite layers over which Cu(II), Cu(I), and Cu(0) species were identified is presented here. The obtained materials were characterized by a wide range of analytical methods, such as X-ray diffraction, electron microscopy (TEM, SEM), X-ray photoelectron (XPS), and UV-VIS spectroscopy. The antimicrobial efficiency was evaluated using qualitative and quantitative standard methods and standard clinical microbial strains. A significant aspect of this composite is that the antimicrobial properties were evidenced both in the presence and absence of the light, as result of competition between photo and electrical effects. However, the antibacterial effect was similar in darkness and light for all samples. Because no photocatalytic properties were found in the absence of copper, the results sustain the antibacterial effect of the electric field (generated by the electrostatic potential of the composite layer) both under the dark and in light conditions. In this way, the composite layers supported on the TiO2 microparticles' surface can offer continuous antibacterial protection and do not require the presence of a permanent light source for activation. However, the antimicrobial effect in the dark is more significant and is considered to be the result of the electric field effect generated on the composite layer.

Revealing and Attenuating the Electrostatic Properties of Tubulin and Its Polymers.

Tubulin is an electrostatically negative protein that forms cylindrical polymers termed microtubules, which are crucial for a variety of intracellular roles. Exploiting the electrostatic behavior of tubulin and microtubules within functional microfluidic and optoelectronic devices is limited due to the lack of understanding of tubulin behavior as a function of solvent composition. This work displays the tunability of tubulin surface charge using dimethyl sulfoxide (DMSO) for the first time. Increasing the DMSO volume fractions leads to the lowering of tubulin's negative surface charge, eventually causing it to become positive in solutions >80% DMSO. As determined by electrophoretic mobility measurements, this change in surface charge is directionally reversible, i.e., permitting control between -1.5 and + 0.2 cm2  (V s)-1 . When usually negative microtubules are exposed to these conditions, the positively charged tubulin forms tubulin sheets and aggregates, as revealed by an electrophoretic transport assay. Fluorescence-based experiments also indicate that tubulin sheets and aggregates colocalize with negatively charged g-C3 N4 sheets while microtubules do not, further verifying the presence of a positive surface charge. This study illustrates that tubulin and its polymers, in addition to being mechanically robust, are also electrically tunable.

Mathematical model of electromigration allowing the deviation from electroneutrality.

The structure of the double layer on the boundary between solid and liquid phases is described by various models, of which the Stern-Gouy-Chapman model is still commonly accepted. Generally, the solid phase is charged, which also causes the distribution of the electric charge in the adjacent diffuse layer in the liquid phase. We propose a new mathematical model of electromigration considering the high deviation from electroneutrality in the diffuse layer of the double layer when the liquid phase is composed of solution of weak multivalent electrolytes of any valence and of any complexity. The mathematical model joins together the Poisson equation, the continuity equation for electric charge, the mass continuity equations, and the modified G-function. The model is able to calculate the volume charge density, electric potential, and concentration profiles of all ionic forms of all electrolytes in the diffuse part of the double layer, which consequently enables to calculate conductivity, pH, and deviation from electroneutrality. The model can easily be implemented into the numerical simulation software such as Comsol. Its outcome is demonstrated by the numerical simulation of the double layer composed of a charged silica surface and an adjacent liquid solution composed of weak multivalent electrolytes. The validity of the model is not limited only to the diffuse part of the double layer but is valid for electromigration of electrolytes in general.

Dual Piezoelectric Energy Investing and Harvesting Interface for High-Voltage Input.

A novel harvesting interface for multiple piezoelectric transducers (PZTs) is proposed for high-voltage energy harvesting. Pre-biasing a PZT prior to its mechanical deformation increases its damping force, resulting in higher energy extraction. Unlike the conventional harvesters where a PZT-generated output is assumed to be continuous sinusoidal and output polarity is assumed to be alternating every cycle, PZT-generated output from human motion is expected to be random. Therefore, in the proposed approach, energy is invested to the PZT only when PZT deformation is detected. Upon the motion detection, energy stored at a storage capacitor (CSTOR) from earlier energy harvesting cycle is invested to pre-bias PZT, enhancing energy extraction. The harvested energy is transferred to back CSTOR for energy investment on the next cycle and then excess energy is transferred to the battery. In addition, partial electric charge extraction (PECE) is adapted to extract a partial amount of charges from the PZT every time its voltage approaches the process limit of 40 V. Simulations with 0.35 µm BCD process show 7.61× (with PECE only) and 8.38× (with PECE and energy investment) improvement compared to the conventional rectifier-based harvesting scheme Proposed harvesting interface successfully harvests energy from excitations with open-circuit voltages up to 100 V.

Microstructures of encapsulates and their relations with encapsulation efficiency and controlled release of bioactive constituents: A review.

Vitamins, peptides, essential oils, and probiotics are examples of health beneficial constituents, which are nevertheless heat-sensitive and possess poor chemical stability. Various encapsulation methods have been applied to protect these constituents against thermal and chemical degradations. Encapsulates prepared by different methods and/or at different conditions exhibit different microstructures, which in turn differently influence the encapsulation efficiency as well as retention of encapsulated core materials. This review provides a summary of various microstructures resulted from the use of selected encapsulation methods or systems, namely, spray coating; co-extrusion; emulsion-, micelle-, and liposome-based; coacervation; and ionic gelation encapsulation, at different conditions. Subsequent effects of the different microstructures on encapsulation efficiency and retention of encapsulated core materials are mentioned and discussed. Encapsulates having compact microstructures resulted from the use of low-surface tension and low-viscosity encapsulants, high-stability encapsulation systems, lower loads of core materials to total solids of encapsulants and appropriate solidification conditions have proved to exhibit higher encapsulation efficiencies and better retention of encapsulated core materials. Encapsulates with hollow, dent, shrunken microstructures or thinner walls resulted from inappropriate solidification conditions and higher loads of core materials, on the other hand, possess lower encapsulation efficiencies and protection capabilities. Encapsulates having crack, blow-hole or porous microstructures resulted from the use of high-viscosity encapsulants and inappropriate solidification conditions exhibit the lowest encapsulation efficiencies and poorest protection capabilities. Compact microstructures and structures formed between ionic biopolymers could be used to regulate the release of encapsulated cores.

Surface, adhesiveness and virulence aspects of Candida haemulonii species complex.

The emerging opportunistic pathogens comprising the Candida haemulonii complex (C. haemulonii [Ch], C. duobushaemulonii [Cd] and C. haemulonii var. vulnera[Chv]) are notable for their intrinsic antifungal resistance. Different clinical manifestations are associated with these fungal infections; however, little is known about their biology and potential virulence attributes. Herein, we evaluated some surface properties of 12 clinical isolates of Ch (n = 5), Cd (n = 4) and Chv (n = 3) as well as their virulence on murine macrophages and Galleria mellonella larvae. Scanning electron microscopy demonstrated the presence of homogeneous populations among the species of the C. haemulonii complex, represented by oval yeasts with surface irregularities able to form aggregates. Cell surface hydrophobicity was isolate-specific, exhibiting high (16.7%), moderate (25.0%) and low (58.3%) hydrophobicity. The isolates had negative surface charge, except for one. Mannose/glucose- and N-acetylglucosamine-containing glycoconjugates were evidenced in considerable amounts in all isolates; however, the surface expression of sialic acid was poorly detected. Cd isolates presented significantly higher amounts of chitin than Ch and Chv. Membrane sterol and lipid bodies, containing neutral lipids, were quite similar among all fungi studied. All isolates adhered to inert surfaces in the order: polystyrene > poly-L-lysine-coated glass > glass. Likewise, they interacted with murine macrophages in a quite similar way. Regarding in vivo virulence, the C. haemulonii species complex were able to kill at least 80% of the larvae after 120 hours. Our results evidenced the ability of C. haemulonii complex to produce potential surface-related virulence attributes, key components that actively participate in the infection process described in Candida spp.

Antibacterial activity of cardiotoxin-like basic polypeptide from cobra venom.

Antibacterial activity of the three-finger toxins from cobra venom, including cytotoxin 3 from N. kaouthia, cardiotoxin-like basic polypeptide A5 from N. naja (CLBP), and alpha-neurotoxin from N. oxiana venom, was investigated. All toxins failed to influence Gram-negative bacteria. The most pronounced activity against Bacillus subtilis was demonstrated by CLBP. The latter is ascribed to the presence of additional Lys-residues within the membrane-binding motif of this toxin.

Electrostatic analysis of bacterial expansins.

Expansins are a family of proteins with plant cell wall remodeling-activity, which bind cell wall components through hydrophobic and electrostatic interactions. A shallow area on the surface of the protein serves as the polysaccharide binding site (PBS) and it is composed of conserved residues. However, electric charge differences on the opposite face of the PBS produce basic, neutral, or acidic proteins. An analysis of forty-four bacterial expansins, homologues of BsEXLX1, revealed two main groups defined by: (a) the presence or absence of disulfide bonds; and (b) by the proteins isoelectric point (pI). We determined the location of the residues responsible for the pI on the structure of representative expansins. Our results suggest that the electric charge at the opposite site of the PBS may help in substrate differentiation among expansins from different species; in addition, electrostatic polarization between the front and the back of the molecule could affect expansin activity on cellulose.

High-Frequency (1 kHz) Spinal Cord Stimulation-Is Pulse Shape Crucial for the Efficacy? A Pilot Study.

OBJECTIVES: Conflicting data regarding the efficacy of high-frequency spinal cord stimulation (HF SCS) has prompted the issue of the possible importance of the shape of the stimulating pulses. The aim of this pilot study was to compare HF SCS applied with monophasic and biphasic pulses of two different durations with conventional SCS in a rat model of neuropathic pain. MATERIALS AND METHODS: Rats were operated with lesions of sciatic nerve branches according to the spared nerve injury procedure (SNI). Animals, which developed pathological tactile hypersensitivity after surgery, were implanted with four-polar miniature SCS leads. SCS was applied during 60 min with either conventional current parameters (monophasic pulse width [PW]: 200 µsec; 50 Hz and amplitude 80% of the motor threshold [MT]), or with high-frequency SCS (1 kHz) with monophasic or biphasic pulses, the latter with pulse widths of either 24 (12 + 12) or 48 (24 + 24) µsec. The outcomes were examined regarding change of tactile hypersensitivity during the one-hour SCS period and with two tests of thermal sensitivity. RESULTS: Conventional monophasic SCS, as well as HF SCS applied with monophasic PW = 24 µsec or with biphasic PW = 48 (24 + 24) µsec, had similar suppressive effects on tactile hypersensitivity. Solely, HF SCS applied with biphasic pulses with a total PW of 24 (12 + 12) µsec demonstrated no effect. Thermal hypersensitivity was unaffected by HF SCS with all pulse varieties. CONCLUSIONS: There is no significant difference in efficacy between HF SCS applied with low amplitude ("subparesthetic") monophasic and biphasic pulses. However, short PWs providing only 12 µsec of cathodal stimulation was ineffective, presumably because of insufficient electric charge transfer from the lead contacts to the nervous tissue.

A Frequency Up-Conversion Piezoelectric Energy Harvester Shunted to a Synchronous Electric Charge Extraction Circuit.

A frequency up-conversion piezoelectric energy harvester (FUC-PEH) consists of a force amplifier, a piezoelectric stack, a low-frequency oscillator (LFO), and a stop limiter. The force amplifier generates the amplification of stress on the piezoelectric stack. The LFO, comprising a spring and a mass block, impacts the stop limiter during vibration to induce high-frequency oscillations within the piezoelectric stack. In this paper, we represent and simplify the FUC-PEH as a lumped-parameter model based on piezoelectric material constitutive equations and structural dynamic theories. Using the electromechanical analogy, we developed an equivalent circuit model (ECM) of the FUC-PEH. A parametric study was performed to investigate the impact of system parameters, such as spring stiffness and concentrated mass, on the FUC-PEH performance. The collision-induced amplitude truncation (AT) effect enlarges the operation bandwidth. ECM simulations show that low-frequency input excitation is converted into a high-frequency output response, enhancing the energy conversion efficiency. Furthermore, we aimed to improve the FUC-PEH's performance using a synchronous electric charge extraction (SECE) circuit. Using the ECM approach, we established a system-level model that considers the electromechanical coupling behavior. The simulation results provide insights into the performance of FUC harvesters with SECE circuits and offer valuable design guidance.

Methodology to measure atmospheric nanoparticles charge.

Atmospheric pollution has become a key aspect for sustainable development world-wide. Lack of measurements of atmospheric nanoparticles properties at different geographic locations limits the understanding of the role atmospheric particulate matter plays in multiple biophysical and environmental processes and its corresponding risks for human beings. This study presents a method to measure atmospheric primary nanoparticle, secondary nanoparticle and microparticle data. Moreover, a process for samples characterization is proposed combining different spectroscopy techniques.•The method allows researcher to collect, measure, store and characterize atmospheric nanoparticles properties including their electric charge.•A specific sample characterization is proposed, based on different techniques such as TEM and RAMAN spectroscopy.•The outcomes of the approach give science the chance to study new themes such as the importance of particulate matter charge in transmission of infectious respiratory diseases; the role of electric charge in pollutants deposition in the respiratory tract; the link between electric atmospheric charge of nanoparticles and meteorological variables.

Oxygen-limited pyrolysis and incineration impact on biochar transport.

At present, studies on biochar transport have focused on biochar obtained by oxygen-limited pyrolysis, which may differ from conventional biochar produced by incineration in nature. This work investigated the transport and retention mechanisms of three types of oxygen-limited pyrolytic biochar and three types of traditional biochar in saturated porous media. The results showed that the specific surface area of the three oxygen-limited pyrolysis biochar (180-200 m2·g-1) was higher than that of the traditional biochar (50-60 m2·g-1). Therefore, the retention capacity of pyrolytic biochar is strong and the permeability is less than 0.1. The absolute value of the zeta potential of traditional biochar is greater than 30 mV, and the electrostatic repulsion generated is stronger, with a peak penetration rate of 0.16. Moreover, the zeta potential of biochar and traditional biochar is regulated by pH value and ionic strength. In acidic conditions or solutions with high ionic strength, the zeta potentials of the six types of biochar changed to about - 15 mV, and the second minimum value was less than 0, indicating that there was a tendency for sedimentation. This study provides a new perspective for assessing the transport and environmental risks of biochar in the environment.

Using QSAR Models to Predict Mitochondrial Targeting by Small-Molecule Xenobiotics Within Living Cells.

Prediction of mitochondrial targeting, or prediction of exclusion from mitochondria, of small-molecule xenobiotics (biocides, drugs, probes, toxins) can be achieved using an algorithm derived from QSAR modeling. Application of the algorithm requires knowing the chemical structures of all ionic species of the xenobiotic compound in question, and for certain numerical structure parameters (AI, CBN, log P, pK a, and Z) to be obtained for all such species. Procedures for specification of the chemical structures; estimation of the structure parameters; and application of the algorithm are described in an explicit protocol.

Viscoelastically active sutures - A stitch in time?

We present results to show that a commercially available polypropylene suture filament (Ethicon Prolene), following annealing and tensile creep can, after creep load removal, release viscoelastically stored energy over a period of several weeks. Specifically, over 0.1-1000 h, the suture undergoes a time-dependent contraction of ~4% and, following a short recovery time (~3 min) to a fixed strain, produces a progressively increasing recovery force of ~0.1-1 N. We suggest that this time-dependent energy release may facilitate wound healing by the action of viscoelastically induced mechanotransduction (VIM). Moreover, our recent (published) findings have led to evidence of reduced hydrophobicity from viscoelastically recovering polymeric filaments and speculation that this may emanate from the long-term release of electric charges. Thus, we propose that the latter may enhance the VIM mechanism. In this paper, we report on the direct detection of these charges and the first findings from an investigation involving the presence of cell cultures on Prolene samples that are (i) viscoelastically recovering, (ii) annealed only and (iii) in as-received condition. From (i), the results demonstrate a significant increase in cell motility, with migration towards the suture, compared to (ii) and (iii). This suggests greater stimulation of the wound healing process, an effect which is expected to continue for the duration of the viscoelastic recovery period.

K Deprivation Modulates the Primary Metabolites and Increases Putrescine Concentration in Brassica napus.

Potassium (K) plays a crucial role in plant growth and development and is involved in different physiological and biochemical functions in plants. Brassica napus needs higher amount of nutrients like nitrogen (N), K, phosphorus (P), sulfur (S), and boron (B) than cereal crops. Previous studies in B. napus are mainly focused on the role of N and S or combined deficiencies. Hence, little is known about the response of B. napus to K deficiency. Here, a physiological, biochemical, and molecular analysis led us to investigate the response of hydroponically grown B. napus plants to K deficiency. The results showed that B. napus was highly sensitive to the lack of K. The lower uptake and translocation of K induced BnaHAK5 expression and significantly declined the growth of B. napus after 14 days of K starvation. The lower availability of K was associated with a decrease in the concentration of both S and N and modulated the genes involved in their uptake and transport. In addition, the lack of K induced an increase in Ca2+ and Mg2+ concentration which led partially to the accumulation of positive charge. Moreover, a decrease in the level of arginine as a positively charged amino acid was observed which was correlated with a substantial increase in the polyamine, putrescine (Put). Furthermore, K deficiency induced the expression of BnaNCED3 as a key gene in abscisic acid (ABA) biosynthetic pathway which was associated with an increase in the levels of ABA. Our findings provided a better understanding of the response of B. napus to K starvation and will be useful for considering the importance of K nutrition in this crop.

Electrical characterization of circulation weather types in Northern Spain based on atmospheric nanoparticles measurements: A pilot study.

The electrical component of the atmosphere is a key element to understand bio-effects of atmospheric processes. In this paper an attempt was made to find possible interactions between air masses arriving in Santander, Northern Spain, and electrical properties of nanoparticles measured in this zone. A methodological approach is proposed to characterize electrically the predominant weather types in the study area. An electrical low pressure impactor device (ELPI®+) was used to measure atmospheric particles net charge and particle net charge distribution in real time in July 2018, among other parameters. Data from two specific channels [0.054-0.071 µm] and [2.5-3.0 µm] has been initially used. Atmospheric circulation was defined attending to two, subjective and objective, weather type classifications. Back trajectories of nanoparticles were also computed by the Hybrid Single-Particle Lagrangian Integrated Trajectory model. Results confirm that atmospheric nanoparticles charge varies according to their size. The highest mean absolute charge is associated with local circulation in Santander for both channels. The studied nanoparticles show a quicker reaction to weather conditions than microparticles. They also have a significant correlation with meteorological variables for 18 synoptic groups found, but humidity. Microparticles [2.5-3.0 µm] are negatively related with air humidity, mainly with S-SE circulation pattern.

Improvement of biodistribution profile of a radiogallium-labeled, αvß6 integrin-targeting peptide probe by incorporation of negatively charged amino acids.

OBJECTIVE: Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers. Since αvß6 integrin has been reported as a promising target for PDAC diagnosis, we previously developed H-Cys(mal-NOTA-67Ga)-(Gly)6-A20FMDV2-NH2 ([67Ga]CG6) as an αvß6 integrin-targeting probe. Although [67Ga]CG6 specifically binds to αvß6 integrin-positive xenografts, the uptake of [67Ga]CG6 in the organs surrounding the pancreas, such as the liver and spleen, was comparable to that in the αvß6 integrin-positive xenografts. We hypothesized that the undesirable accumulation of [67Ga]CG6 in those organs was caused by the positive charges of [67Ga]CG6 (+ 3). In this study, we aimed to decrease [67Ga]CG6 uptake in the liver and spleen by reducing the electric charges of the probe. METHODS: We synthesized H-Cys(mal-NOTA-67Ga)-(Asp)6-A20FMDV2-NH2 ([67Ga]CD6) and evaluated its affinity to αvß6 integrin via in vitro competitive binding assay. Isoelectric points of the probes were determined by electrophoresis. Biodistribution study, autoradiography, and immunostaining for ß6 integrin were conducted using αvß6 integrin-positive and negative tumor-bearing mice. RESULTS: In vitro competitive binding assay showed that the alteration of the linker had a negligible impact on the affinity of [67Ga]CG6 to αvß6 integrin. The results of electrophoresis revealed that [67Ga]CG6 was positively charged whereas [67Ga]CD6 was negatively charged. In the biodistribution study, the uptake of [67Ga]CD6 in the αvß6 integrin-positive xenografts was significantly higher than that in the αvß6 integrin-negative ones at 60 and 120 min. The uptake of [67Ga]CD6 in the liver and spleen was more than two-fold lower than that of [67Ga]CG6 at both time points. In the immunohistochemistry study, the radioactivity accumulated areas in the autoradiogram of the αvß6 integrin-positive xenograft roughly coincided with ß6 integrin-expressing areas. CONCLUSION: We have successfully reduced the nonspecific uptake in the liver and spleen by altering the linker amino acid from G6 to D6. [67Ga]CD6 overcame the drawbacks of [67Ga]CG6 in its biodistribution.

Nanostructured DNA for the delivery of therapeutic agents.

DNA and RNA, the nucleic acids found in every living organism, are quite crucial, because not only do they store the genetic information, but also they are used as signals through interaction with various molecules within the body. The nature of nucleic acids, especially DNA, to form double-helix makes it possible to design nucleic acid-based nanostructures with various shapes. Because the shapes as well as the physicochemical properties determine their interaction with proteins or cells, nanostructured DNAs will have different features in the interaction compared with single- or double-stranded DNA. Some of these unique features of nanostructured DNA make ways for efficient delivery of therapeutic agents to specific targets. In this review, we begin with the factors affecting the properties of nanostructured DNA, followed by summarizing the methods for the development of nanostructured DNA. Further, we discuss the characteristics of nanostructured DNA and their applications for the delivery of bioactive compounds.