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Chlorophyll-a is the pigment whose concentration is an important indicator for the development of microalgae biomass. This study aims at evaluating the concentration of chlorophylls in the biomass of granular activated algae, using acetone and 90% ethanol for the extraction procedures applied. Concentrations of chlorophyll a, b and c were determined by applying three calculation types: methods proposed by Jeffrey and Humphrey for the extracts in acetone, Ritchie method for ethanolic extracts, and monochromatic method with acidification for ethanolic extracts. Experimental findings show that the solvent 90% ethanol is more efficient than acetone for extracting chlorophyll from biomass of granular activated algae. Also, by comparing results obtained by the two methods proposed for ethanolic extracts, it was found that the values obtained through the acidification method are influenced by the volume of hydrochloric acid added to the organic chlorophylls extract.

The paper reports the relative humidity (RH) sensing response of a resistive sensor employing oxidized carbon nanohorns - based sensing layer. The sensing layer is deposited on an interdigitated (IDT) structure, comprising a Si substrate, a SiO 2 layer, and IDT electrodes. The structure exhibits good RH sensitivity when varying RH from 0% up to 90%, either in humid nitrogen or in a humid air environment. The conductivity of the sensing layer decreases, while the RH level increases. During the interaction with the water molecules (acting as electron donors), the number of holes will decrease and oxidized single-walled carbon nanohorns (SWCNHs), considered normally p -type semiconductor, will become more resistive. The sensing mechanism is explained in terms of the Hard Soft Acid Base (HSAB) paradigm, building on the fact that water molecules are hard bases, while oxidized carbon nanohorns can be virtually assimilated with hard acids.

The food industry is a high consumer of polymer packing materials, sealing materials, and engineering components used in production equipment. Biobased polymer composites used in the food industry are obtained by incorporating different biogenic materials into the structure of a base polymer matrix. Renewable resources such as microalgae, bacteria, and plants may be used as biogenic materials for this purpose. Photoautotrophic microalgae are valuable microorganisms that are able to harvest sunlight energy and capture CO2 into biomass. They are characterized by their metabolic adaptability to environmental conditions, higher photosynthetic efficiency than terrestrial plants, and natural macromolecules and pigments. The flexibility of microalgae to grow in either low-nutrient or nutrient-rich environments (including wastewater) has led to the attention for their use in various biotechnological applications. Carbohydrates, proteins, and lipids are the main three classes of macromolecular compounds contained in microalgal biomass. The content in each of these components depends on their growth conditions. In general, proteins represent 40–70% of microalgae dry biomass, followed by carbohydrates (10–30%) and lipids (5–20%). A distinctive feature of microalgae cells is the presence of light-harvesting compounds such as photosynthetic pigments carotenoids, chlorophylls, and phycobilins, which are also receiving growing interest for applications in various industrial fields. The study comparatively reports on polymer composites obtained with biomass made of two species of green microalgae: Chlorella vulgaris and filamentous, gram-negative cyanobacterium Arthrospira. Experiments were conducted to reach an incorporation ratio of the biogenic material into the matrix in the 5–30% range, and the resulting materials were characterized by their mechanical and physicochemical properties.

Human Papilloma Virus (HPV) is the virus responsible for the most common and widespread sexually-transmitted infection. Most sexually active people will acquire at least one type of HPV in their lifetime and some may be repeatedly infected. In most cases, HPV infection is transient and asymptomatic, but when the infection persists it can cause benign diseases, precancerous lesions and malignancies of various locations. Low risk HPV types can produce proliferative lesions either in the skin or mucosa, whereas high risk types possess carcinogenic potential. This paper is a review of the latest data in the literature regarding the clinical manifestations of HPV infections, current prevention and therapeutic possibilities.

Although extensively studied, psoriasis still has negative consequences and is associated with multiple comorbidities, including metabolic syndrome. The severity of psoriasis seems to influence the occurrence of diagnostic criteria for metabolic syndrome. 208 patients diagnosed with psoriasis were identified, who were divided into lots depending on the severity of psoriasis, but also to the presence or absence of metabolic syndrome. Interpretation of statistical data was done with SPSS V21 (Statistical Package for Social Science) and MEDCALC (Statistical Software). The coexistence of severe psoriasis with metabolic syndrome increases the risk of developing cardiovascular diseases by 2.97 or greater, with a confidence interval of [1.60, 5.51], than that of patients with severe psoriasis who have no metabolic syndrome. The hypothesis was statistically confirmed by p = 0.003. Analyzing the total group with psoriasis by severity, we found the following distribution: from the total number of 208 patients, 39 (18.8%) had severe psoriasis, 83 (39.9%) moderate psoriasis and 86 (41.3%) mild psoriasis. The higher incidence of metabolic syndrome in patients with psoriasis is evidenced by the Pearson Chi-Square test, where p [0.001. The association of metabolic syndrome in patients with psoriasis is evident. The more severe the psoriasis, the more likely it is to develop metabolic syndrome.

Psoriasis is a chronic inflammatory systemic disorder that associates many cardiovascular comorbidities. The association between psoriasis and cardiovascular disease is a complex one, which implies many risk factors, such as age, gender, heredity, smoking, alcohol and stress. The prognosis of patients with psoriasis may be improved by identifying and reduction of these cardiovascular risk factors. The objective of our study was to determine the prevalence of cardiovascular risk factors among patients with psoriasis from Bucharest and Ilfov county, Romania. 634 individuals from the general population were initially included. From these individuals, 208 patients with psoriasis have been selected for inclusion in our observational study. The patients were selected from Elias Emergency Hospital of Bucharest, Romania, and through the family doctors praxis, between 2010-2017. Of the 634 individuals from the general population, 208 patients (33%) were identified as patients with a diagnosis of vulgar psoriasis, confirmed by the dermatologist, forming the study group. The presence of risk factors is consistent with the presence of cardiovascular disease (23%) in the studied group. Patients with psoriasis, without cardiovascular diseases, have an increased risk of developing them throughout their lives. Patients with psoriasis have a very high risk of developing life-long cardiovascular disease, because of a multitude of risk factors associated with psoriasis. Intervention on modifiable risk factors for cardiovascular disease can be mediated by a family doctor, who can monitor the development over time and may also intervene early when appropriate.

Psoriasis is a chronic inflammatory disease that affects the patients’ quality of life. In psoriatic patients, the quality of life is generally low due to multiple co-morbidities, treatments, stigma and misperceptions about this condition. Sexual dysfunction, in both women and men, is a comorbidity that may impact the quality of life of these patients, in addition to those listed above. Because the recognition of sexual dysfunction by the patient can be difficult and considered shameful, it is necessary for the family doctor to intervene to improve the sexual health of these patients.

Expansion of measles cases is an alarm signal in Romania, with most of the European Union in our country. There is a clear need for higher rates of vaccination of the population. Romania ranks first in Europe in terms of measles deaths as well as cases of measles exported to other EU countries. Neighboring countries such as Bulgaria and Hungary succeed to have a much better management of measles.

This paper presents the relative humidity (RH) sensing response of a resistive sensor employing sensing layers based on a ternary nanocomposite comprising graphene oxide-oxidized carbon nanohorns-polyvinylpyrrolidone (GO-CNHox–PVP), at 1/1/1, 1/2/1, and 1/3/1 w/w/w mass ratios. The sensing structure is composed of a silicon substrate, a SiO2 layer, and interdigitated transducers (IDT) electrodes, on which the sensing layer is deposited via the drop-casting method. The morphology and the composition of the sensing layers are investigated through scanning electron microscopy (SEM) and RAMAN spectroscopy. The RH sensing capability of each carbonaceous nanocomposite-based thin film was analyzed by applying a current between the two electrodes and by measuring the voltage difference when varying the RH from 0% to 100% in humid nitrogen. The sensors have a room temperature response comparable to that of a commercial humidity sensor and are characterized by a rapid response, excellent linearity, good sensitivity, and recovery time. The manufactured sensing devices’ transfer functions were established, and we extracted the response and recovery times. While the structures with GO/CNHox/PVP at 1/1/1 ratio (w/w/w) had the best performance in terms of relative sensibility, response time, and recovery time, the sensors employing the GO/CNHox/PVP nanocomposite at the 1/2/1 ratio (w/w/w) had the best linearity. Moreover, the ternary mixture proved to have much better sensing properties compared to CNHox and CNHox-PVP-based sensing layers in terms of sensitivity and linearity. Each component of the ternary nanocomposites’ functional role is explained based on their physical and chemical properties. We analyzed the potential mechanism associated with the sensors’ response, among these, the effect of the p-type semiconductor behavior of CNHox and GO, correlated with swelling of the PVP, was dominant and led to increased resistance of the sensing layer.

This paper reports, for the first time, on the electrical percolation threshold in oxidized carbon nanohorns (CNHox)–polyvinylpyrrolidone (PVP) films. We demonstrate—starting from the design and synthesis of the layers—how these films can be used as sensing layers for resistive relative humidity sensors. The morphology and the composition of the sensing layers are investigated through Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and RAMAN spectroscopy. For establishing the electrical percolation thresholds of CNHox in PVP, these nanocomposite thin films were deposited on interdigitated transducer (IDT) dual-comb structures. The IDTs were processed both on a rigid Si/SiO2 substrate with a spacing of 10 µm between metal digits, and a flexible substrate (polyimide) with a spacing of 100 µm. The percolation thresholds of CNHox in the PVP matrix were equal to (0.05–0.1) wt% and 3.5 wt% when performed on 10 µm-IDT and 100 µm-IDT, respectively. The latter value agreed well with the percolation threshold value of about 4 wt% predicted by the aspect ratio of CNHox. In contrast, the former value was more than an order of magnitude lower than expected. We explained the percolation threshold value of (0.05–0.1) wt% by the increased probability of forming continuous conductive paths at much lower CNHox concentrations when the gap between electrodes is below a specific limit. The change in the nanocomposite’s longitudinal Young modulus, as a function of the concentration of oxidized carbon nanohorns in the polymer matrix, is also evaluated. Based on these results, we identified a new parameter (i.e., the inter-electrode spacing) affecting the electrical percolation threshold in micro-nano electronic devices. The electrical percolation threshold’s critical role in the resistive relative-humidity sensors’ design and functioning is clearly emphasized.

Silk fibroin is a natural polymer with a unique repetitive structure that translates to extraordinary properties in terms of processability and mechanical properties. The Bombyx mori silk has a molecular weight of ∼415 kDa and consists of a light chain and a heavy chain. Its heavy chain is organized into 12 crystalline domains. Each of these crystalline domains contains subdomains of ∼70 amino acid containing blocks. It is well understood that the heavy chain of the protein is responsible for its processing versatility and excellent mechanical properties; however, the need for the high number of monomeric repeating units is unclear, and the individual properties of crystalline regions compared to those of the full-length protein are not understood. The work described herein assessed the possibility of using recombinant crystalline regions as alternative biomaterials for applications such as tissue adhesives. Our results indicate that while the two tested substructures do not fully recapitulate the native silk fibroin's properties, they appear to be a suitable alternative for the production of silk-based medical adhesives.

Outer ear infections (OE) affect millions of people annually with significant associated healthcare costs. Incorrect administration or non-compliance with the treatment regimen can lead to infection persistence, recurrence, antibiotic resistance, and in severe cases aggravation to malignant otitis externa. Such issues are particularly pertinent for military personnel, patients in nursing homes, the geriatric population, for patients with head or hand tremors and for those with limited or no access to proper healthcare. With the intent of using traditional material science principles to deconvolute material design while increasing relevance and efficacy, we developed a single application, cold-chain independent thixotropic drug delivery system. This can be easily applied into the ear as a liquid, then gels to deliver effective concentrations of antibiotics against bacterial strains commonly associated with OE. The system maintains thixotropic properties over several stress/no stress cycles, shows negligible swelling and temperature dependence, and does not impact the minimum inhibitory concentration or bactericidal effects of relevant antibiotics. Moreover, the thixogels are biocompatible and are well tolerated in the ear. This drug delivery system can readily translate into a user-friendly product, could improve compliance via a single application by the diagnosing health care provider, is expected to effectively treat OE and minimize the development of antibiotic resistance, infection recurrence or exacerbation.

Organic&ndash, inorganic ternary nanohybrids consisting of oxidized-single walled carbon nanohorns-SnO2-polyvinylpyrrolidone (ox-SWCNH/SnO2/PVP) with stoichiometry 1/1/1 and 2/1/1 and ox-SWCNH/ZnO/PVP = 5/2/1 and 5/3/2 (all mass ratios) were synthesized and characterized as sensing films of chemiresistive test structures for ethanol vapor detection in dry air, in the range from 0 up to 50 mg/L. All the sensing films had an ox-SWCNH concentration in the range of 33.3&ndash, 62.5 wt%. A comparison between the transfer functions and the response and recovery times of these sensing devices has shown that the structures with ox-SWCNH/SnO2/PVP = 1/1/1 have the highest relative sensitivities of 0.0022 (mg/L)&minus, 1, while the devices with ox-SWCNH/SnO2/PVP = 2/1/1 have the lowest response time (15 s) and recovery time (50 s) for a room temperature operation, proving the key role of carbonic material in shaping the static and dynamic performance of the sensor. These response and recovery times are lower than those of &ldquo, heated&rdquo, commercial sensors. The sensing mechanism is explained in terms of the overall response of a p-type semiconductor, where ox-SWCNH percolated between electrodes of the sensor, shunting the heterojunctions made between n-type SnO2 or ZnO and p-type ox-SWCNH. The hard&ndash, soft acid&ndash, base (HSAB) principle supports this mechanism. The low power consumption of these devices, below 2 mW, and the sensing performances at room temperature may open new avenues towards ethanol sensors for passive samplers of environment monitoring, alcohol test portable instruments and wireless network sensors for Internet of Things applications.

The objective of this study is to design and synthetize an oxidized single wall carbon nanohorns (SWCNHs) - polyvinylpyrrolidone (PVP) composite film as potential sensing material for resistive humidity sensor. Raman spectroscopy is used to investigate the nanohybrid formation and components interaction. Comparative results are presented for the percolation threshold values determined for 2 study-cases: carbon nanohorns in PVP film deposited on either rigid (Si / SiO 2 ) or flexible substrate (polyimide). While in the first case, the percolation threshold occurs at a concentration of oxidized SWCNHs in the nanocomposite matrix in the range (0.05-0.1)% (w/w), in the second instance, the concentration of SWCNHs for the percolation threshold is between (2-3.5)% (w/w). Experimental findings are explained in terms of size effects in the geometry of the studied structures. The key role played by the electrical percolation threshold in the resistive sensing capabilities of the synthesized nanocomposite towards water molecules is described.

This paper presents the fabrication and functional characterization of a novel chemiresistive sensor for room temperature ethanol vapors detection by means of sensing films consisting of oxidized single wall carbon nanohorn (ox-SWCNH) / tin dioxide (SnO 2 ) / polyvinylpyrrolidone (PVP) in the mass ratio equal to 1/1/1 and 2/1/1. These sensors with ox-SWCNH concentration higher than 33 wt%, which is much above percolation threshold in the composite (below 0.1 wt%), has shown unexpected high sensitivities for ethanol vapor concentrations in air in the range of 0.2-25 below 2 mg/L, as well as in the range of 2-25 mg/L. These sensors may be attractive for low power Internet of Things (IoT).

This paper presents the architecture of a signal-conditioning circuit designed for resistive sensors and based on the properties of a Wheatstone quarter-bridge. The bridge comprises one sensing element, consisting of a small-resistance-variation sensor and three fixed resistors. The proposed circuit was designed using NI Multisim software; simulations were carried out for various scenarios in order to ensure maximum accuracy versus component values and tolerances. The output signal of the proposed circuit was found to have less than 0.5 % non-linearity relative error for a sensing element value variation of 3 ohms.

Tetraethyl orthosilicate (TEOS)-based hydrogels, with shear stress response and drug releasing properties, can be formulated simply by TEOS hydrolysis followed by volume corrections with aqueous solvents and pH adjustments. Such basic thixotropic hydrogels (thixogels) form via the colloidal aggregation of nanoparticulate silica. Herein, we investigated the effects of the nanoparticulate building blocks on the drug release properties of these materials. Our data indicate that the age of the hydrolyzed TEOS used for the formulation impacts the nanoparticulate structure and stiffness of thixogels. Moreover, the mechanism of formation or the disturbance of the nanoparticulate network significantly affects the release profiles of the incorporated drug. Collectively, our results underline the versatility of these basic, TEOS-only hydrogels for drug delivery applications.

Vitiligo is a chronic, asymptomatic, disease that affects the patient from a cosmetic point of view. It is characterized by the appearance of depigmented areas on the skin or mucous membranes. Depending on the morphology of the lesions, vitiligo can be classified into: segmental, non-segmented or mixed. Vitiligo is associated with a range of autoimmune disorders, most commonly autoimmune thyroid diseases, alopecia areata, halo nevi, psoriasis, diabetes, etc. Etiology is not entirely elucidated, autoimmune theory related to specific genetic mutations being the most studied.

The paper demonstrates how the Hard-Soft Acid Base (HSAB) theory can be used as a valuable criterion in the selection process of semiconducting metal oxides (MOX) suitable as sensing layers for ammonia detection. Six different cases of ammonia detection performed by chemiresistive sensors employing MOX and related nanocomposites as sensing layers are identified and discussed. The role of HSAB as an efficient selection tool for appropriate sensing layer (any type of gas), is further reinforced by analyzing and discussing literature results on MOX-based trimethylamine sensing layers. By analyzing the operation of a fiber-optic ammonia sensor, we demonstrate that the HSAB principle can be also successfully applied to the selection of sensing layers for detectors employing other sensing principles, different than the chemiresistive one. Changing the sensing paradigm (i.e., the amino groups-based compounds are part of the sensing layer, rather than part of the analyte), the paper shows that these types of molecules (polymers, carbon nanotubes, ionic liquids) are appropriate constituents of a CO2 sensing layer, in full accordance to the HSAB criteria.

The prevalence of obesity is increasing and morbidity and mortality increase with it. Vitamin D plays an important role in obesity. Determining the exact relationship between obesity and vitamin D may represent a new perspective in the approach and treatment of obesity. Clarifying whether supplementation with vitamin D in overweight people can prevent obesity and whether supplementation in obese people can help weight loss are essential.

In this study, a resistive humidity sensor for moisture detection at room temperature is presented. The thin film proposed as a critical sensing element is based on a quaternary hybrid nanocomposite CNHox//SnO2/ZnO/PVP (oxidated carbon nanohorns–tin oxide–zinc oxide–polyvinylpyrrolidone) at the w/w/w/w ratios of 1.5/1/1/1 and 3/1/1/1. The sensing structure consists of a Si/SiO2 dielectric substrate and interdigitated transducers (IDT) electrodes, while the sensing film layer is deposited through the drop-casting method. Morphology and composition of the sensing layers were investigated through scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction, and Raman spectroscopy. Each quaternary hybrid nanocomposite-based thin film’s relative humidity (RH) sensing capability was analyzed by applying a direct current with known intensity between two electrodes and measuring the voltage difference when varying the RH from 0% to 100% in a humid nitrogen atmosphere. While the sensor with CNHox/SnO2/ZnO/PVP at 1.5/1/1/1 as the sensing layer has the better performance in terms of sensitivity, the structure employing CNHox//SnO2/ ZnO/PVP at 3/1/1/1 (mass ratio) as the sensing layer has a better performance in terms of linearity. The contribution of each component of the quaternary hybrid nanocomposites to the sensing performance is discussed in relation to their physical and chemical properties. Several alternative sensing mechanisms were taken into consideration and discussed. Based on the measured sensing results, we presume that the impact of the p-type semiconductor behavior of CNHox, in conjunction with the swelling of the hydrophilic polymer, is dominant and leads to the overall increasing resistance of the sensing film.

The paper looks into the use of Nanostructured metal oxides as sensing layer for ethanol. Using the HSAB rules for analyzing the chemiresistive ethanol sensor based on semiconducting metal oxides, three different cases have been identified and are discussed in the paper.

In this paper, ZnO-1.4 wt% Graphene (ZnO-G) hybrids were synthesized by sonochemistry of high acoustic power density. XRD, SEM and RAMAN spectroscopy have shown that (i) ZnO-G crystallite particles of 18 nm were obtained after drying and this was mainly due to sonoprocessing, (ii) Nanoflower-like 3D architectures of ZnO-G hybrids were obtained at pH=14, which de-structured gradually at pH of 11.5, ending with an agglomeration of nanopetals at pH=8.5, (iii) Sonochemistry created a major disorder of graphene, with G peak splitting into two peaks at 1575 cm-1and 1605 cm-1 and (iv) maximum operation of gas sensors based on ZnO-G should be much below 450°C in air, to preserve chemical stability of ZnO-G layer.

In this paper, we present the relative humidity (RH) sensing response of a chemiresistive sensor, employing sensing layers based on a ternary nanohybrids comprised of holey carbon nanohorns (CNHox), titanium (IV) oxide, and polyvinylpyrrolidone (PVP) at 1/1/1/(T1), 2/1/1/(T2), and with 3/1/1 (T3) mass ratios. The sensing device is comprised of a silicon-based substrate, a SiO2 layer, and interdigitated transducer (IDT) electrodes. The sensitive layer was deposited via the drop-casting method on the sensing structure, followed by a two-step annealing process. The structure and composition of the sensing films were investigated through scanning electron microscopy (SEM), Raman spectroscopy, and X-ray diffraction (XRD). The resistance of the ternary nanohybrid-based sensing layer increases when H increases between 0% and 80%. A different behavior of the sensitive layers is registered when the humidity increases from 80% to 100%. Thus, the resistance of the T1 sensor slightly decreases with increasing humidity, while the resistance of sensors T2 and T3 register an increase in resistance with increasing humidity. The T2 and T3 sensors demonstrate a good linearity for the entire (0–100%) RH range, while for T1, the linear behavior is limited to the 0–80% range. Their overall room temperature response is comparable to a commercial humidity sensor, characterized by a good sensitivity, a rapid response, and fast recovery times. The functional role for each of the components of the ternary CNHox/TiO2/PVP nanohybrid is explained by considering issues such as their electronic properties, affinity for water molecules, and internal pore accessibility. The decreasing number of holes in the carbonaceous component at the interaction with water molecules, with the protonic conduction (Grotthus mechanism), and with swelling were analyzed to evaluate the sensing mechanism. The hard–soft acid-base (HSAB) theory also has proven to be a valuable tool for understanding the complex interaction of the ternary nanohybrid with moisture.

We report the relative humidity (RH) sensing response of a resistive sensor, employing sensing layers, based on a quaternary organic–inorganic hybrid nanocomposite comprising oxidized carbon nanohorns (CNHox), graphene oxide (GO), tin dioxide, and polyvinylpyrrolidone (PVP), at 1/1/1/1 and 0.75/0.75/1/1/1 mass ratios. The sensing structure comprises a silicon substrate, a SiO2 layer, and interdigitated transducer (IDT) electrodes. The sensing film was deposited via the drop-casting method on the sensing structure. The morphology and the composition of the sensing layers were investigated through Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), and RAMAN spectroscopy. The organic–inorganic quaternary hybrid-based thin film’s resistance increased when the sensors were exposed to relative humidity ranging from 0 to 100%. The manufactured devices show a room temperature response comparable to that of a commercial capacitive humidity sensor and characterized by excellent linearity, rapid response and recovery times, and good sensitivity. While the sensor with CNHox/GO/SnO2/PVP at 0.75/0.75/1/1 as the sensing layer has the best performance in terms of linearity and recovery time, the structures employing the CNHox/GO/SnO2/PVP at 1/1/1/1 (mass ratio) have a better performance in terms of relative sensitivity. We explained each constituent of the quaternary hybrid nanocomposites’ sensing role based on their chemical and physical properties, and mutual interactions. Different alternative mechanisms were taken into consideration and discussed. Based on the sensing results, we presume that the effect of the p-type semiconductor behavior of CNHox and GO, correlated with swelling of PVP, dominates and leads to the overall increasing resistance of the sensing layer. The hard–soft acid–base (HSAB) principle also supports this mechanism.

The current paper reports on a sonochemical synthesis method for manufacturing nanostructured (typical grain size of 50 nm) SrTi0.6Fe0.4O2.8 (Sono-STFO40) powder. This powder is characterized using X ray-diffraction (XRD), Mössbauer spectroscopy and Scanning Electron Microscopy (SEM), and results are compared with commercially available SrTi0.4Fe0.6O2.8 (STFO60) powder. In order to manufacture resistive oxygen sensors, both Sono-STFO40 and STFO60 are deposited, by dip-pen nanolithography (DPN) method, on an SOI (Silicon-on-Insulator) micro-hotplate, employing a tungsten heater embedded within a dielectric membrane. Oxygen detection tests are performed in both dry (RH = 0%) and humid (RH = 60%) nitrogen atmosphere, varying oxygen concentrations between 1% and 16% (v/v), at a constant heater temperature of 650 °C. The oxygen sensor, based on the Sono-STFO40 sensing layer, shows good sensitivity, low power consumption (80 mW), and short response time (25 s). These performance are comparable to those exhibited by state-of-the-art O2 sensors based on STFO60, thus proving Sono-STFO40 to be a material suitable for oxygen detection in harsh environments.

The synthesis and application to dye-sensitized solar cells (DSSC) of a new dihexyloxy-substituted triphenylamine-based organic dye is reported. The dye design, based on the push–pull concept, consists of dihexyloxy-substituted triphenylamine as an electron donor and a cyanoacrylic acid as an anchoring group and electron acceptor connected through a π-conjugated bridge. The electron spacer containing furan and thiophene moieties was employed in the dye sensitizer for expansion of the π-conjugated fragment to adjust the absorption spectra and HOMO–LUMO levels of the dye. The relationship between the dye chemical structure and the photophysical, electrochemical, and photovoltaic properties determined by spectral, electrochemical, photovoltaic experiments, and density functional theory calculations was thoroughly investigated. The photovoltaic performance of the dye as sensitizer was assessed in DSSC cells realized using electrolytes containing the iodide/triiodide redox couple. The cells obtained with the new dye show a power conversion efficiency of 5.14%, without using any coadsorbant and optimization.

In this paper, we describe a novel concept for the realization of protective chemical gloves with end of service life indication in acidic and bases aqueous solutions. It consists in “inserting” a pH indicator layer based on bromophenol blue, surfactant and viscosity intensifying agent in between a top and a bottom polymeric layer of the glove. The bottom polymeric layer near the skin of the user is 10% thick with respect to top polymeric layer. Depending on pH value of aqueous solution, the top surface of glove will change to yellow for pH 4.6.

In this work, we report facile synthesis and characterization of new cellulose acetate-hydroxyapatite membranes for water purification and biomedical applications. The membranes were synthesized from a polymer solution in N, N’-dimethylformamide (12% wt.) where different concentrations of hydroxyapatite (1, 2, 4% wt. based on the amount of polymer) were dispersed using sonication. The synthesis of membranes was carried out by precipitation employing phase inversion using deionized water. The morphological and structural characterization of the synthesized membranes was carried out using SEM, EDS and FT-IR. Thermal characterization (TGA & DTG) and water flows analysis of the synthesized membranes was also carried out. The SEM analysis confirmed the presence of hydroxyapatite micro/nanostructured particles in the membrane as well as significant changes in the morphology of the membranes surface. The presence of inorganic compounds was also found to influence the thermal or hydrodynamic properties of the composite membranes, leading to a more stable hydrodynamic behavior, flow variation in time being much lower compared to the control membrane of cellulose acetate.

Ear infections are a commonly-occurring problem that can affect people of all ages. Treatment of these pathologies usually includes the administration of topical or systemic antibiotics, depending on the location of the infection. In this context, we sought to address the feasibility of a single-application slow-releasing therapeutic formulation of an antibiotic for the treatment of otitis externa. Thixotropic hydrogels, which are gels under static conditions but liquefy when shaken, were tested for their ability to act as drug controlled release systems and inhibit Pseudomonas aeruginosa and Staphylococcus aureus, the predominant bacterial strains associated with outer ear infections. Our overall proof of concept, including in vitro evaluations reflective of therapeutic ease of administration, formulation stability, cytocompatibility assessment, antibacterial efficacy, and formulation lifespan, indicate that these thixotropic materials have strong potential for development as otic treatment products.

Nanosized TiO 2 layers containing polyethylene glycol (PEG) with 20,000 molecular weight were prepared by sol–gel method and deposited on three different substrates: microscope standard slides, Fluorine doped Tin Oxide (FTO) glass and Silicon, followed by thermal treatment at 450 °C. The effects of the substrate on the microstructural, morphological, chemical and optical properties of the films have been studied by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM), Atomic Force Microscopy (AFM), X-ray Photo-electron Spectroscopy (XPS) and Spectroscopic Ellipsometry (SE). The XRD showed that the film crystallization depends very much on the substrate used, thus the films deposited on glass are amorphous even after 1 h thermal treatment at 450 °C, while the films deposited on Silicon and FTO substrates are crystallized in anatase phase, in good agreement with the TEM analysis. The XPS analysis showed that a rather high carbon relative concentration in the TiO 2 film (without PEG) exists; this suggests that an unavoidable carbon contamination occurs and is not related on the presence or absence of PEG. The thickness and surface roughness of the films are clearly dependent on the substrate type. The flat surfaces of glass and Si lead to the formation of thinner TiO 2 films (around 30 nm thicknesses), while the FTO substrate surface leads to thicker film (thickness ~100 nm). The porosity of TiO 2 films as found by SEM and TEM analyzes is dependent of substrate type; small pore sizes up to 20 nm are characteristic for the films deposited on glass, while larger pore sizes up to 200 nm are found for the films deposited on FTO substrate. Not least, the film transmissions in the visible region are also substrate dependent and the highest values (80%) were obtained for the films deposited on glass.

Multilayered titania (TiO 2 ) films have been prepared via sol–gel dip-coating method from a tetraethyl-orthotitanate solution that contains 2 g of polyethylene glycol (PEG) with different molecular weight (6000, 20,000 and 35,000). The films were deposited on fluorine doped tin oxide (FTO) coated glass and annealed by a thermal treatment at 450 °C for 30 min. We demonstrated how the structure, the morphology and the optical properties of the films can be controlled by varying the PEG molecular weight and number of depositions. The correlation between these parameters and the film properties was investigated. Sol–gel deposited and PEG doped TiO 2 films demonstrate better properties for their use in solar cell applications, by enhancing the transmittance value in the 380–540 nm range.

The paper reviews the state-of-the-art in oxygen sensing, focusing on low power technologies suitable for portable applications. Employment of novel materials in electrochemical, optical, acoustic and resistive oxygen sensing structures, substantiated by extensive theoretical considerations and experimental data, is discussed. Merits and drawbacks of each technology are presented, together with possible means of optimization.

This paper reports on the design and synthesis of a talc-impregnated polyimide film exhibiting reduced relative humidity (RH) hysteresis. The morphology of both simple polyimide and talc-impregnated polyimide RH sensing layers are investigated by means of Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). When deposited on quartz crystal microbalance (QCM) substrates, the talc-impregnated polyimide layer yields a highly linear response and a resonant frequency hysteresis improvement as high as 36% with respect to simple polyimide. These experimental results recommend the proposed layer as suitable for high performance RH capacitive sensors.

This paper introduces the Hard Soft Acid Base (HSAB) concept as a promising tool for the selection of gas sensing layers. Target gas molecule — sensitive layer tandems are discussed and interpreted in the terms of this theory. Sensing layers suitable for carbon dioxide, nitrogen dioxide, sulphur dioxide, and hydrogen sulphide detection are presented and classified according to this concept. For oxygen and mineral acids detection, an indirect HSAB approach is discussed. The paper explains how the HSAB principle can be useful in designing gas sensing layers for different types of sensing structures, such as: surface acoustic waves (SAW), colorimetric, chemoresistive, etc.

Within this paper we present a thermodynamic methodology for the selection of non-toxic metals which could be used as lead-free consumable anodes in electrochemical galvanic oxygen sensors. Starting from thermodynamic nobility theory, metals like copper, bismuth or antimony are proposed to replace lead in future galvanic O 2 sensors. The thermodynamic theory provides voltage windows which increase from copper (0.7 V), to bismuth (0.857 V) and antimony (1.076 V). The experimental voltage windows are smaller than the theoretical ones, but these experimental values increase in the same order from Cu, to Bi and Sb, as predicted by our methodology.

The synthesis of pyrene-1-butyric acid (PBA)-doped polyaniline (PANI) and its oxygen sensing properties, through fluorescence quenching, are reported. The structures of both undoped PANI (emeraldine) and PBA-doped PANI are investigated by means of Fourier Transform InfraRed (FT-IR) spectroscopy. The O 2 sensing capability of the synthesized layer is demonstrated through fluorescence spectroscopy performed at different air pressure values. PBA-doped PANI is expected to lead to a fluorophore with better stability and reliability than free PBA. This could bring real benefits to the overall functioning of industrial O2 sensors based on fluorescence quenching.

Two CO 2 sensing mechanisms, based on the Hard Soft Acids Bases (HSAB) and Bronsted-Lowry theories, are discussed and compared. They are evaluated by selecting amino groups-based coating layers, which are deposited on Surface Acoustic Wave (SAW) devices for CO 2 detection. Experimentally measured CO 2 sensitivities of different coating layers, such as polyallylamine (PAA), polyethyleneimine (PEI), nanocomposite matrix based on PAA-aminocarbon nanotubes and PEI-aminocarbon nanotubes, emeraldine, 4-sulfocalix[4]arene-doped polyaniline, matrix based emeraldine and carbonic anhydrase (PACA) are compared and evaluated according to their corresponding sensing mechanism.

The Hard Soft Acid Base (HSAB) theory is introduced as a new tool to select or design sensitive materials for carbon dioxide detection with SAW-BAW (Surface Acoustic Waves - Bulk Acoustic Waves) devices. According to HSAB, CO 2 is hard acid, thus small organic or inorganic molecules, or polymers which can act as hard bases could be suitable candidates as sensing layers for carbon dioxide detection. As a consequence of this theory, we propose the following polymers as potential candidates for CO 2 sensing: simple polyallylamine, N-substituted polyallylamine, polydiallylamine and polyvinylamine, and mixtures of these polymers. The SAW device coated with one of the selected polymers, polyallyamine, shows good sensitivity for CO 2 concentration (in the range 500–5000 ppm), long term stability and repeatability.