Coefficient Kp Research Articles

Enhanced piezoelectric properties for potassium sodium niobate lead-free piezoelectric ceramics prepared by microwave technology

Potassium-sodium niobate (Na, K)NbO3 (NKN) powder was synthesized at low temperature via microwave-assisted hydrothermal solovthermal method (MHSM). The resultant powder was characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). XRD results showed that pure (Na, K)NbO3 powder with a single perovskite structure was successfully synthesized when the concentration of mineralization exceeded 1 M. In order to reduce the volatilization of alkaline elements, NKN ceramics derived from 5M-powder were prepared in a microwave furnace. Microstructure, stoichiometry, and electrical properties of the obtained ceramics were investigated. The piezoelectric coefficient (d33), electromechanical coupling coefficient (kp) and remnant polarization (Pr) of the sample sintered at 1050 ℃ show optimal values of 132 pC/N, 38% and 26.3 µC/cm2, respectively. The results indicate that the microwave heating is a promising method for synthesizing and sintering NKN-based ceramics.

Justification of optimal parameters for quadcopter PID-controllers with frame sizes up to 150 mm

Unmanned aerial vehicles with a frame of up to 150 mm are used in agriculture to solve problems in smart greenhouses. Calculating the values of PID-regulators when optimizing the drone operation allows to reduce the risks of flight controller misadjustment and increase the accuracy of its control in different flight conditions. The aim of the study is to calculate the optimal values` of the PID controllers of the UAV, develop an algorithm for coefficient calculation, and compute the proportional, integrating, and differentiating errors along the deviation axes. The authors have developed a quadcopter with a take-off weight of up to 150 g for monitoring an industrial greenhouse. The mathematical theory of optimal control and stabilization was applied. A research analysis on the optimization of quadcopter flight was carried out. Experimental research in mechanics on adjusting the stability and acceleration of the quadcopter prototype during flight was carried out. Based on the mathematical formula for calculating the control signal, an algorithm was developed to calculate the coefficients and to compute the proportional, integrating, and differentiating errors in the axes of control deviation of the quadcopter’s brushless motors. Optimized settings of the PID-regulator stabilization system in Betaflight Configurator program for stable flight of the quadcopter prototype are selected, taking into account design and technical characteristics. The optimal values of coefficients (Kp, Ki, Kd) on the roll, pitch and yaw axes for the quadcopter prototype under development were justified.

Evidence of direct and converse magnetoelectric coupling in eco-friendly 0.75(0.94Na0.5Bi0.5TiO3-0.06BaTiO3)–0.25(CoFe2O4) particulate composite

Magnetoelectric (ME) multiferroic composite exhibits the ME effect, and their interaction between piezoelectric and magnetic phase is measured in terms of ME coupling (α). ME coupling is an interesting and characteristic property of ME materials and can be evaluated by direct and indirect methods. In this work, the solid-state sintering technique has been adopted to synthesize the lead-free 0.75(0.94Na0.5Bi0.5TiO3-0.06BaTiO3)–0.25CoFe2O4 (NBBT-CFO) composite. The X-ray diffraction patterns and uniform distribution of closely packed grains reveal the coexistence of constituent phases in the composite. This composite reveals room-temperature multiferroic properties. The room temperature dielectric constant (ε′) of the poled sample displays the resonance and anti-resonance peaks at a particular frequency ∼ 455 kHz and 450 kHz, respectively. The estimated value of the electromechanical coupling coefficient (kP) is 16.69%. The direct ME and converse ME coupling study has been done through the Polarization (P) vs Electric field (E) and Magnetization (M) vs Magnetic field (H) hysteresis loop measurements of magnetically and electrically poled and unpoled samples, respectively. The variation in the polarization and magnetization value reveals the presence of direct and converse ME coupling in the composite.

Earth Pressure of the Trapdoor Problem Using Three-Dimensional Discrete Element Method

Load transformation from the yielding part of the soil to the adjacent part is known as the soil arching effect, which plays an important role in the design of various geotechnical infrastructures. Terzaghi’s trapdoor test was an important milestone in the development of theories on soil arching. The research on earth pressure of the trapdoor problem is presented in this paper using the three-dimensional (3D) discrete element method (DEM). Five 3D trapdoor models with different heights are established by 3D DEM software PFC 3D. The variation of earth pressure on the trapdoor with the downward movement of the trapdoor, the distribution of vertical earth pressure along the horizontal direction, the distribution of vertical earth pressure along the vertical direction, the distribution of lateral earth pressure coefficient along the depth direction, the magnitude and direction of contact force chain are studied, respectively. Related research results show that the earth pressure on the trapdoor decreases rapidly after the downward movement of the trapdoor, and then reaches the minimum earth pressure. After that, the earth’s pressure will rise slightly, and whether this phenomenon occurs depends on the depth ratio. For the bottom soil, due to the stress transfer caused by the soil arching effect, the ratio of earth pressure in the loose area decreases, while the ratio of earth pressure in the stable area increases. With the trapdoor moving down, the vertical earth pressure along the depth in the stable zone is basically consistent with the initial state, which shows an approximate linear distribution. After the trapdoor moves down, the distribution of earth pressure along with the depth in the loose area changes, which is far less than the theoretical value of vertical earth pressure of its self-weight. Because of the compression of the soil on both sides, the lateral earth pressure coefficient of most areas on the central axis of the loose zone is close to the passive earth pressure coefficient Kp. The existence of a ‘soil arch’ can be observed intuitively from the distribution diagram of the contact force chain in the loose zone.

Effect of different managements with drip irrigation (tape)

Conventional irrigation methods to new methods have been altered with respect to reduction of water resources and climate change. Considering the corn cultivation development, applying modern irrigation methods namely drip irrigation with the aim of improving the efficiency of water consumption as well as the zone under cultivation has been investigated. In this research, the performance of corn (SC 704) in various managements of drip irrigation (by strip method) both in single-row and double-row planting patterns was considered with a variety of densities. This test was carried out on random complete blocks in the form of a 3-repetitive Split Design in Isfahan-Iran during the years 2018–2019. Four irrigation levels containing: 80, 100 and 120% of full water requirement with drip irrigation (strip) and 100% of water requirement with normal drip irrigation were utilized. The results indicated that applying the aforementioned drip tapes and different surface treatments with soil and water monitoring, the water consumption of corn seasonal irrigation can be saved by 81, 71, 61, 52 and 36% compared to normal drip irrigation without soil, water and root monitoring, respectively. Seasonal yield (Kc), the yield response coefficient (Ky), and pan coefficient (Kp) for corn were 0.80, 0.76 and 0.97, respectively.

A Novel Ferroptosis Inhibitor UAMC-3203, a Potential Treatment for Corneal Epithelial Wound.

Corneal wound, associated with pain, impaired vision, and even blindness, is the most common ocular injury. In this study, we investigated the effect of a novel ferroptosis inhibitor, UAMC-3203 (10 nM-50 µM), in corneal epithelial wound healing in vitro in human corneal epithelial (HCE) cells and ex vivo using alkali-induced corneal wounded mice eye model. We evaluated in vivo acute tolerability of the compound by visual inspection, optical coherence tomography (OCT), and stereomicroscope imaging in rats after its application (100 µM drug solution in phosphate buffer pH 7.4) twice a day for 5 days. In addition, we studied the partitioning of UAMC-3203 in corneal epithelium and corneal stroma using excised porcine cornea. Our study demonstrated that UAMC-3203 had a positive corneal epithelial wound healing effect at the optimal concentration of 10 nM (IC50 value for ferroptosis) in vitro and at 10 µM in the ex vivo study. UAMC-3203 solution (100 µM) was well tolerated after topical administration with no signs of toxicity and inflammation in rats. Ex-vivo distribution study revealed significantly higher concentration (~12-38-fold) and partition coefficient (Kp) (~52 times) in corneal epithelium than corneal stroma. The UAMC-3203 solution (100 µM) was stable for up to 30 days at 4 °C, 37 °C, and room temperature. Overall, UAMC-3203 provides a new prospect for safe and effective therapy for corneal wounds.

Effects of (Bi0.5Li0.5)TiO3 addition on microstructures, electrical properties and thermal stability of BiFeO3-BaTiO3 piezoelectric ceramics

Herein, lead-free 0.7BiFeO3-(0.297-x)BaTiO3-x(Bi0.5Li0.5)TiO3+0.003BiGaO3+0.01MnO2 (abbreviated as BF-BT-xBLT, 0 ≤ x ≤ 0.0096) ceramics have been prepared by conventional solid-state sintering. The phase structures, microstructures, piezoelectric, ferroelectric, dielectric, and thermal stability of these materials were investigated. The XRD analysis show that rhombohedral and tetragonal phases coexist in the phase structure of BF-BT-xBLT ceramic. As the BLT concentration rises, the grain size first increases to 8.6 μm and then decreases to 6.14 μm. The grain size decreased from 7.68 μm to 5.02 μm with the decrease of sintering temperature. The piezoelectric, ferroelectric and dielectric properties of the ceramic increase first and then decrease as BLT concentration increases. The optimal electrical properties are obtained by adding 0.0012 BLT, piezoelectric constant d33 = 152 pC/N, electromechanical coupling coefficient kp = 0.321, mechanical quality factor Qm = 58.184, remnant polarization Pr = 25.07 μC/cm2, Curie temperature Tc = 485 °C and depolarization temperature Td = 465 °C. The BLT addition concentration may modify the aforementioned BF-BT ceramic structures and properties, while the decrease of sintering temperature from 960 °C to 880 °C causes modest decreases of relative density of BF-BT-0.0072BLT ceramics from 94.73% to 93.56% and d33 from 146 pC/N to 135 pC/N. Enhanced piezoelectric properties of d33 = 135 pC/N, kp = 0.279, and Qm = 63.713 are obtained for BF-BT-0.0072BLT ceramic even at an extremely low sintering temperature of 880 °C. In addition, the d33 of BF-BT-0.0012BLT ceramic reached 392 pC/N at 352 °C by in-situ dynamic d33 testing. This indicates the piezoelectric properties of the piezoelectric ceramic in its actual operating state. The main novelty of this study is the relatively high piezoelectric properties obtained at low sintering temperature and the d33 reaching 392 pC/N at 352 °C. The findings suggest that the ceramic is a viable material for the use of lead-free piezoelectric ceramics.

Cross-cultural adaptation of discrimination and vigilance scales in ELSA-Brasil.

To describe the process of cross-cultural adaptation for the use in Brazil of the everyday discrimination scale (EDS) and the heightened vigilance scale (HVS) applied in the Longitudinal Study of Adult Health (ELSA-Brasil). Conceptual, item and semantic equivalence analyses were conducted by a group of four epidemiologists; evaluation of measurement equivalence (factorial analysis of configural, metric and scalar structures, according to sociodemographic characteristics) and reliability. A total of 11,987 participants responded to the discrimination scale, and a subsample of 260 people participated in the test-retest study. In the case of HVS, 8,916 people responded, while 149 individuals did so in the test-retest study. The scales presented conceptual, item and semantic equivalence pertinent in the Brazilian context, in addition to adequate correspondence of referential/denotative meaning of terms and also of the general/connotative of the items. The confirmatory factor analysis of EDS revealed a unidimensional structure, with residual correlations between two pairs of items, presenting configural and metric invariance among the four subgroups evaluated. Scalar invariance was identified according to sex and age group, but it was not observed for race/color and education. Heightened vigilance showed low loads and high residuals, with inadequate adjustment indicators. For the items of the discrimination scale the weighted kappa coefficient (Kp) ranged from 0.44 to 0.78, and the intraclass correlation coefficient (ICC) was 0.87. For HVS items, the Kp ranged from 0.47 to 0.59 and the ICC was 0.83. Although there are correlated items, it was concluded that the EDS is a promising scale to evaluate experiences of perceived discrimination in Brazilian daily life. However, the heightened vigilance scale did not present equivalence of measurement in the current format.

EXTH-103. DISCOVERY AND PHARMACOLOGICAL CHARACTERIZATION OF SKL27969, A NOVEL BRAIN-PENETRATING PRMT5 INHIBITOR WITH STRONG ANTITUMOR ACTIVITY, IN GLIOBLASTOMA AND BRAIN METASTASIS PRECLINICAL MODELS

Abstract Protein arginine methyltransferase 5 (PRMT5), a type II methyltransferase, regulates cellular processes such as survival, proliferation, and apoptosis by inducing symmetric arginine dimethylation of multiple cellular proteins involved in the regulation of cellular transcription and RNA splicing. Elevated tumor PRMT5 protein level has recently been correlated with poor prognosis and poor patient survival in various human cancers, including glioblastoma multiforme (GBM), lung cancer, breast cancer, and ovarian cancer. SKL27969 is a highly selective and potent PRMT5 inhibitor that is designed for brain penetration. It strongly binds to S-adenosylmethionine (SAM)-bound PRMT5/MEP50 (methylosome protein 50), leading to potent cellular symmetric dimethylarginine (SDMA) inhibition with an IC50 of 3.4 nM. Cell line panel profiling of SKL27969 revealed a broad spectrum of anti-proliferative activity in various cancer cell types, including CNS tumors, solid cancers prone to spread to brain, other solid cancers, and hematologic cancers. SKL27969 showed excellent brain exposure, with total and unbound partition coefficient (Kp and Kpuu) values of 6.57 and 1.08, respectively, and high tumor-to-plasma ratio, which resulted in significant survival benefit in orthotopic GBM xenograft models and metastatic brain cancer models such as intracranial xenograft models of non-small cell lung cancer (NSCLC) or triple-negative breast cancer (TNBC). Administration of SKL27969 showed strong tumor growth suppression in subcutaneous xenograft models of GBM, NSCLC, or TNBC. High correlation between tumor and plasma SDMA levels after SKL27969 treatment were observed in the preclinical models. Furthermore, SKL27969 showed potentiation of DNA damage when used in combination with DNA-damaging agents, which may suggest possible benefit as a combination therapy. Given the therapeutic target potential of PRMT5 in glioblastoma and other brain metastatic cancers, and the preclinical efficacy of SKL27969, these results have enabled the initiation of Phase 1/2 open-label, multicenter dose-finding study in patients with advanced solid tumors (NCT05388435).

Toxicokinetics, Percutaneous Absorption and Tissue Distribution of Benzophenone-3, an UV Filtering Agent, in Rats.

The aim of this study was to evaluate in vitro skin permeation and deposition, in vivo toxicokinetics, percutaneous absorption and tissue distribution of benzophenone-3 (BP-3) in rats. Four transdermal formulations containing BP-3 were prepared and evaluated for in vitro skin permeation and deposition of BP-3 using Franz diffusion cells. A gel formulation was used in subsequent in vivo percutaneous absorption due to its high in vitro skin permeation and deposition. Compared to intravenous (i.v.) injection, the prolonged terminal t1/2 (3.1 ± 1.6 h for i.v. injection and 18.3 ± 5.8 h for topical application) was observed indicating occurrence of flip-flop kinetics after topical application. The bioavailability of BP-3 after topical application was 6.9 ± 1.8%. The tissue-to-plasma partition coefficient (kp) for testis, considered a toxic target for BP-3, was less than 1.. Overall, findings of this study may be useful for risk assessment of BP-3.

Environmental processes and fate of PAHs at a shallow and enclosed bay: West Nanao Bay, Noto Peninsula, Japan

From August 2019 to August 2020, particulate and dissolved polycyclic aromatic hydrocarbons concentrations (PAHs) were analyzed in the water body of West Nanao Bay, Japan, to determinate their levels, environmental pathways, and ecological risks at this remote but shallow and semi-enclosed bay. The 14 targeted PAHs were analyzed by high performance liquid chromatography-fluorescence detector. Even when water column stratifies, the summatory of 14 targeted dissolved PAHs did not follow significantly change with depth. Results agreed with our previous findings in the surface distribution at the bay and can be attributed to long retention time of the water mass of the semi-enclosed bay. Suspended solids start precipitating according to their size; with biggest particles rapidly settling in the proximities of river mouths. Partition coefficients (Kp) varied from 103 to 107, according to molecular weights. In general, highest Kp were found in the nepheloid layer. The risk quotients, RQ∑14 PAHs (NCs) (1.04-174.08), indicated that PAHs represented a very low to low environmental risks.

Absorption, distribution, metabolism, and excretion of [14C]Mefuparib (CVL218), a novel PARP1/2 inhibitor, in rats.

Mefuparib (CVL218) is a novel second-generation poly-ADP-ribose polymerase (PARP) inhibitor for cancer treatment. CVL218 can easily enter the brain. However, the transport mechanism by which CVL218 crosses the blood-brain barrier (BBB) is unknown. (1) [14C] CVL218 metabolism in rats was traced by a liquid scintillation counter and oxidative combustion. (2) Metabolic profiles and metabolites were identified by UHPLC-β-RAM/UHPLC-Fraction Collector and UHPLC-Q Exactive Plus MS. (3) The partition coefficient Kp,uu,brain value was simulated by two strategies. One strategy was using ACD and GastroPlus Software based on the results of intravenous administration pharmacokinetics and plasma protein-binding studies. The reliability was confirmed by comparison with another strategy (brain/plasma distribution study). (1) Rapid drug elimination was observed 24h after intragastric administration. The total cumulative excretion in urine and feces within 168h accounted for 97.15% of the dose. The cumulative radioactive dose recovery in bile was 41.87% within 72h. The drug-related substances were extensively distributed to the tissues within 48h. (2) M8 was the major metabolite in plasma, urine, feces and bile. (3) CVL218 exhibited high brain protein-binding rate (88.16%). The Kp,uu,brain value (8.42) simulated by the simple software strategy was similar to that of the brain/plasma distribution study (7.01). CVL218 is a fast-metabolizing drug and is mainly excreted in feces. The B/P ratio prediction and observation data for CVL218 were consistent. Furthermore, the Kp,uu,brain value indicated that penetration through the BBB might be mediated by uptake transporters.

Assessing Liver-to-Plasma Partition Coefficients and In Silico Calculation Methods: When Does the Hepatic Model Matter in PBPK?

The primary models used in pharmacokinetics (PK) to assess hepatic clearance (CLh ) are the well-stirred (WSM), parallel tube (PTM), and dispersion model (DM) that differ in their internal flow patterns and assumed unbound liver concentrations. Physiologically-Based Pharmacokinetic (PBPK) models require a hepatic intrinsic clearance (CLint ) and tissue-to-plasma partition coefficient (Kp ). Given measured systemic and liver concentration-time profiles, these hepatic models perform similarly but yield model-specific CLint and Kp estimates. This work provides mathematical relationships for the three basic hepatic models and assesses their corresponding PBPK-relevant Kp values with literature-reported single-dose blood and liver concentration-time data of 14 compounds. Model fittings were performed with an open-loop approach where the CLh and extraction ratio (ER) were first estimated from fitting the blood data yielding CLint values for the three hepatic models. The pre-fitted blood data served as forcing input functions to obtain PBPK-operative Kp estimates that were compared with those obtained by the tissue/plasma area ratio (AR), Chen & Gross (C&G) and published in silico methods. The CLint and Kp values for the hepatic models increased with the ER and both showed a rank order being WSM > DM > PTM. Drugs with low ER showed no differences as expected. With model-specific CLint and Kp values, all hepatic models predict the same steady-state Kp (Kp ss ) that is comparable to those from the AR and C&G methods and reported by direct measurement. All in silico methods performed poorly for most compounds. Hepatic model selection requires cautious application and interpretation in PBPK modeling. Significance Statement The three hepatic models generate different single-dose (non-steady-state) values of CLint and Kp in PBPK models especially for drugs with high ER; however, all Kp ss values expected from constant rate infusion studies were the same. These findings are relevant when using these models for IVIVE where a model-dependent CLint is used to correct measured tissue concentrations for depletion by metabolism. This model-dependency may also have an impact when assessing the PK/pharmacodynamic relationships when effects relate to assumed hepatic concentrations.

Predicting skin permeability using HuskinDB

A freely accessible database has recently been released that provides measurements available in the literature on human skin permeation data, known as the ‘Human Skin Database – HuskinDB’. Although this database is extremely useful for sourcing permeation data to help with toxicity and efficacy determination, it cannot be beneficial when wishing to consider unlisted, or novel compounds. This study undertakes analysis of the data from within HuskinDB to create a model that predicts permeation for any compound (within the range of properties used to create the model). Using permeability coefficient (Kp) data from within this resource, several models were established for Kp values for compounds of interest by varying the experimental parameters chosen and using standard physicochemical data. Multiple regression analysis facilitated creation of one particularly successful model to predict Kp through human skin based only on three chemical properties. The model transforms the dataset from simply a resource of information to a more beneficial model that can be used to replace permeation testing for a wide range of compounds.

The Influence of Newly Synthesized Demulsifiers on the Interfacial Rheological Properties of a Naturally Occurring Water/Oil Emulsion.

This research aimed to synthesize new polymeric nonionic demulsifiers (DA, DB, and DC) to break 50% of naturally occurring water/oil emulsions. The prepared demulsifiers were synthesized in only two stages utilizing simple techniques. 1H and 13CNMR, MS, and FTIR spectroscopies were performed to validate the chemical composition of the synthesized demulsifiers. The relative solubility number (RSN) and partition coefficient (Kp) were determined for the three demulsifiers. The interfacial tension (IFT) and dehydration ratios of DA, DB, DC, and their triblock copolymers were investigated. Also, interfacial rheological properties for the three demulsifiers were measured. The findings demonstrate that DB possesses a higher RSN value than DA and DC owing to its hydrophilicity. DC exhibited the lowest IFT value compared to DA, DB, and their corresponding triblock copolymers. DB and DC are more effective in demulsifying than DA and triblock copolymers. DC achieved a 100% dehydration ratio at a low dosage of 75 ppm after 120 min. DC’s remarkable performance can be attributed to its aromatic core, molecular weight, and high interfacial activity. According to the rheological data, a higher dehydrating ratio is attained when the demulsifier has a great capacity to lower the viscoelasticity of the W/O emulsion interface. The maximum decrease in G′ and G″ values was attained by DC. The mechanism of DC’s demulsifying interaction on a naturally occurring W/O emulsion was elucidated.

Discovery of Novel Quinoline-Based Proteasome Inhibitors for Human African Trypanosomiasis (HAT).

Human African Trypanosomiasis (HAT) is a vector-borne disease caused by kinetoplastid parasites of the Trypanosoma genus. The disease proceeds in two stages, with a hemolymphatic blood stage and a meningo-encephalic brain stage. In the latter stage, the parasite causes irreversible damage to the brain leading to sleep cycle disruption and is fatal if untreated. An orally bioavailable treatment is highly desirable. In this study, we present a brain-penetrant, parasite-selective 20S proteasome inhibitor that was rapidly optimized from an HTS singleton hit to drug candidate compound 7 that showed cure in a stage II mouse efficacy model. Here, we describe hit expansion and lead optimization campaign guided by cryo-electron microscopy and an in silico model to predict the brain-to-plasma partition coefficient Kp as an important parameter to prioritize compounds for synthesis. The model combined with in vitro and in vivo experiments allowed us to advance compounds with favorable unbound brain-to-plasma ratios (Kp,uu) to cure a CNS disease such as HAT.

CNS penetration of methotrexate and its metabolite 7-hydroxymethotrexate in mice bearing orthotopic Group 3 medulloblastoma tumors and model-based simulations for children

The brain penetration of methotrexate (MTX) and its metabolite 7-hydroxymethotrexate (7OHMTX) was characterized in non-tumor bearing mice and mice bearing orthotopic Group 3 medulloblastoma. Plasma pharmacokinetic studies and cerebral and ventricular microdialysis studies were performed in animals dosed with 200 or 1000 mg/kg MTX by IV bolus. Plasma, brain/tumor extracellular fluid (ECF) and lateral ventricle cerebrospinal fluid (CSF) MTX and 7OHMTX concentration-time data were analyzed by validated LC-MS/MS methods and modeled using a population-based pharmacokinetic approach and a hybrid physiologically-based model structure for the brain compartments. Brain penetration was similar for MTX and 7OHMTX and was not significantly different between non-tumor and tumor bearing mice. Overall, mean (±SD) model-derived unbound plasma to ECF partition coefficient Kp,uu were 0.17 (0.09) and 0.17 (0.12) for MTX and 7OHMTX, respectively. Unbound plasma to CSF Kp,uu were 0.11 (0.06) and 0.18 (0.09) for MTX and 7OHMTX, respectively. The plasma and brain model were scaled to children using allometric principles and pediatric physiological parameters. Model-based simulations were adequately overlaid with digitized plasma and CSF lumbar data collected in children receiving different MTX systemic infusions. This model can be used to further explore and optimize methotrexate dosing regimens in children with brain tumors.

Effect of Bi3+ and Ti4+ substitution on PbNb2O6 piezoelectric ceramics

In this study, Pb1-2xBi2x(Nb1-xTix)2O6 (PBNTx, x = 0.02–0.08) ceramics with tungsten bronze structure were prepared via the solid-state reaction method. Single orthorhombic ferroelectric phase was detected for all PBNTx ceramics. SEM results indicated fully densified morphology for the samples of x ≥ 0.06. Optimal piezoelectric performance was obtained at the sample of x = 0.08, whose piezoelectric constant (d33) reached to 92 pC/N and Curie temperature (Tc) was up to 593 °C. A notably high electromechanical coupling coefficient (kp) greater than 0.6 was also obtained in this system. The improved piezoelectric performance indicated that Bi3+ and Ti4+ modified PbNb2O6 system is promising for ultrasonic defect detection and transducer applications at high temperatures.

Effect of squalane-based emulsion on polyphenols skin penetration: Ex vivo skin study

Polyphenols have gained attractiveness as ingredients in cosmetic formulations as result of their ability to delay the aging process. However, different factors limit their use, including low solubility and poor skin permeability. In this sense, this study describes the potential of squalane to increase the polyphenols ex vivo skin penetration, incorporated into a water-in-oil emulsion. Polyphenols skin permeation followed the Fick’s first law and, p-coumaric acid, vitexin, schaftoside and ferulic acid had the higher permeability coefficients (Kp = 6.0–8.0 × 10-3 cm-2 h-1). Addition of squalane to phenolic compounds decreased the permeability coefficients (Kp = 4.1–5.9 × 10-3 cm-2 h-1), indicating that squalane increased the retention of polyphenols in the skin. Gentisic acid, ferulic acid, and p-coumaric acid were the only compounds permeating from water-in-oil emulsion, in the first 8 h of study and, according Krosmeyer-Peppas model, its n value was > 1 indicating a high transport resistance from the formulation and throughout the skin. Results suggest squalane as an efficient vehicle to increase the dermal availability increasing phenolic compounds physiological functions, by enhancing the skin retention time where they should exert antiaging effect.

The Effect of Vegetable and Volatile Oils on the Piroxicam Skin Permeability: A Mechanistic Study

Background: Piroxicam is a non-steroidal anti-inflammatory medication for treating fever, discomfort, and inflammation. In addition, piroxicam inhibits cyclooxygenase and lowers prostaglandin synthesis, resulting in analgesic and anti-inflammatory effects. Objectives: This study used Franz diffusion cells made from rat skin primed with sesame, eucalyptus, olive, menthol, clove, and sunflower oils. Methods: Control was hydrated rat skin. Permeability measurements include steady-state flux (Jss), permeability coefficient (Kp), and diffusion coefficient (D). FT-IR was used to compare changes in peak position, differential scanning calorimeter (DSC), mean transition temperature, and the permeability enhancement methods of the penetration enhancer (Tm). The skin acted as a barrier to piroxicam permeability throughout the whole surface, indicating that drug flux was limited by diffusion into the skin. Results: The steady-state flux (Jss) of all penetration enhancers were not significantly different from control, except for clove and menthol oil (4 hours treated) and olive oil (2 and 4 hours treated). Conclusions: Penetration enhancers improved drug permeability through rat skin. Sesame oil, menthol oil, and sesame oil were found to have higher ERflux, ERD, and ERP ratios than water-hydrated skin due to lipid fluidization, lipid structure disruption, and irreversible keratin denaturation.