Monomodal Distribution Research Articles

Protonation isomers of highly charged protein ions can be separated in FAIMS-MS

High-field asymmetric waveform ion mobility spectrometry-mass spectrometry (FAIMS-MS) can resolve over an order of magnitude more conformers for a given protein ion than alternative methods. Such an expansion in separation space results, in part, from protein ions with masses of >29 kDa undergoing dipole alignment in the high electric field of FAIMS, and the resolution of ions that adopt pendular vs free rotor states. In this study, FAIMS-MS, collision-induced dissociation (CID), and travelling wave (TW) IMS-MS were used to investigate the pendular and free rotor states of protonated carbonic anhydrase II (CAII, 29 kDa). The electrospray ionization additive 1,2-butylene carbonate was used to increase protein charge states and ensure extended ion conformations were formed. For relatively high charge states in which dipole alignment occurs (30–38+), FAIMS-MS can baseline resolve the isobaric pendular and free rotor ion populations. For TWIMS-MS, these same charge states resulted in monomodal arrival time distributions with collision cross sections corresponding to highly extended ion conformations. Interestingly, CID of FAIMS-selected pendular and free rotor ion populations resulted in significantly different fragmentation patterns. For example, CID of the dipole aligned CAII 37+ resulted in cleavages C-terminal to residue 183, 192 and 196, whereas cleavage sites for the free rotor population occurred near residues 12 and 238. Given that the cleavage sites are ’directed’ by protonation sites in the CID of protein ions, and highly charged protein ions adopt extended conformations with the same or very similar collision cross sections, these results indicate that the pendular and free rotor populations separated in FAIMS can be attributed to protonation isomers. Moreover, the extent of protein ion charging in FAIMS-MS decreased substantially as the carrier gas flow rate decreased, indicating that ion charging in FAIMS-MS can be limited by proton-transfer reactions. Given that the total mass of proton charge carriers corresponds to less than 0.2% the mass of CAII, we anticipate that FAIMS-MS can be used to separate intact isobaric proteoforms with masses of at least ∼29 kDa that result from alternative sites of post-translational modifications.

Comparative study on the high temperature deformation behaviour of an as-cast Ni base superalloy subjected to different cooling rates after homogenization

Medium alloyed as-cast nickel base superalloy was subjected to two different cooling rates (fast and slow) after homogenization which resulted in mono-modal and bi-modal distribution of gamma prime (γ′) precipitates. Both the materials were subjected to high temperature deformation over a range of temperatures and strain rates. Irrespective of the strain rate used, the material subjected to fast cooling exhibited high compressive yield strength and flow softening characteristics when compared to the slow cooled material in the sub-solvus regime. Detailed microstructural investigation carried out using scanning and transmission electron microscope to ascertain the micro-mechanism revealed varying precipitate – dislocation interaction mechanism in both the materials. Higher flow softening and cracking in the fast cooled material is attributed to glide plane softening due to planar slip and the presence of fine network of carbides along the grain boundaries respectively. In the super-solvus regime, the flow stress of both the materials was comparable and both the materials exhibited discontinuous dynamic recrystallization (DDRX). Further, the slow cooled material exhibited lower critical strain for DDRX initiation and also better recrystallization kinetics irrespective of the processing conditions. Higher recrystallization kinetics in the slow cooled material is attributed to the concurrent particle simulated nucleation (PSN) at the coarse MC type carbide boundaries.

Microbiological, physicochemical, textural characteristics and oxidative stability of butter produced from high-pressure homogenisation treated cream at different pressures

Microbiological, physicochemical, and textural characteristics, and oxidative stability was investigated of butter produced from raw cream treated with high-pressure homogenisation (HPH) at 0 (control), 10, 20, 30, 50, or 70 MPa. HPH treatment of cream increased lightness and decreased yellowness of butter. Firmness of all butter samples was between 97 (control) and 380 N (70 MPa). HPH decreased the spreadability of butter dependent on increasing pressure. A monomodal fat particle size distribution was determined in all butter samples; D[3.2] ranged from 25.25 to 125.5 μm and HPH decreased average particle size compared with the control. The induction time of butter ranged from 27.40 (control) to 39.61 h (70 MPa). Above 50 MPa, Salmonella, and yeast and moulds were completely inactivated whilst coliforms and staphylococci were not detected in butter from HPH treated cream at 70 MPa, indicating that HPH can improve the microbial quality of butter produced from raw cream.

Preparation and Evaluation of Intraperitoneal Long-Acting Oxaliplatin-Loaded Multi-Vesicular Liposomal Depot for Colorectal Cancer Treatment.

Colorectal cancer with peritoneal metastasis has a poor prognosis because of inadequate responses to systemic chemotherapy. Cytoreductive surgery followed by intraperitoneal (IP) chemotherapy using oxaliplatin has attracted attention; however, the short half-life of oxaliplatin and its rapid clearance from the peritoneal cavity limit its clinical application. Here, a multivesicular liposomal (MVL) depot of oxaliplatin was prepared for IP administration, with an expected prolonged effect. After optimization, a combination of phospholipids, cholesterol, and triolein was used based on its ability to produce MVL depots of monomodal size distribution (1–20 µm; span 1.99) with high entrapment efficiency (EE) (92.16% ± 2.17%). An initial burst release followed by a long lag phase of drug release was observed for the MVL depots system in vitro. An in vivo pharmacokinetic study mimicking the early postoperative IP chemotherapy regimen in rats showed significantly improved bioavailability, and the mean residence time of oxaliplatin after IP administration revealed that slow and continuous erosion of the MVL particles yielded a sustained drug release. Thus, oxaliplatin-loaded MVL depots presented in this study have potential for use in the treatment of colorectal cancer.

Positively charged polymeric nanoparticles improve ocular penetration of tacrolimus after topical administration

Tacrolimus (TAC) is an immunosuppressant with potential use in ophthalmology, especially as a steroid sparing agent. The efficacy of TAC has been investigated in the treatment of different anterior segment inflammatory disorders. However, its use is limited by its poor corneal penetration, which has led to the development of different nanocarriers. In order to overcome this limitation, we prepared positively charged polymeric nanoparticles loaded with tacrolimus (TAC-NPs) for topical ocular application. TAC-NPs were prepared by interfacial polymer deposition following solvent displacement method, using Eudragit® RL100, a cationic polymer. The formulation was characterized and the ocular safety was assessed in vivo by Draize eye test and histopathological analysis. TAC was quantified in aqueous humor to determine the in vivo release of the nanoparticles. TAC-NPs presented suitable physical-chemical characteristics for ocular application, including monomodal size distribution with a mean diameter of 104 ± 1 nm, positive zeta potential and mucoadhesive properties. The monitoring of the physical-chemical characteristics and the multiple light scattering analysis of TAC-NPs suggested their long-term stability. The in vivo safety investigation of TAC-NPs and blank-NPs showed no signs of ocular irritation on the ophthalmological examination and histopathological study, indicating the biocompatibility of this carrier. The nanoparticles were able to deliver TAC for over 36 h with a better performance than the drug suspension. The in vivo release profile of TAC-NPs indicated slower elimination with 1.7-fold higher maximum concentration of TAC and 5.3-fold higher AUC, suggesting increased ocular penetration and bioavailability in addition to extended delivery. TAC-NPs improved the ocular delivery of tacrolimus after topical administration, without causing any ocular irritation. It shows the potential of this carrier as an alternative for ocular delivery of tacrolimus in the treatment of anterior segment inflammatory conditions.

Surface Functionalization of Mesoporous Membranes: Impact on Pore Structure and Gas Flow Mechanisms

Membranes showing monomodal pore size distributions with mean pore diameters of 23, 33, and 60 nm are chemically functionalized using silanes with varying chain length and functional groups like amino, alkyl, phenyl, sulfonate, and succinic anhydrides. Their influence on the morphology, pore structure, and gas flow is investigated. For this, single-gas permeation measurements at pressures around 0.1 MPa are performed at temperatures ranging from 273 to 353 K using He, Ne, Ar, N2, CO, CO2, CH4, C2H4, C2H6, and C3H8. Results show pore size and pore volume linearly depending on the length of functional molecules, as expected for monolayer deposition. However, the gas flow through functionalized membranes is disproportionally decreased up to a factor of around 10. Hence, the decreased pore size and pore volume cannot explain the large decrease in flow. Furthermore, there is no specific dependency between the decrease in flow and temperature or gas type other than the relation proposed by Knudsen (√RTM)-1. Considering the large variety of functional molecules used, it is very surprising that no correlations between the type of functional group and the flow have been found. The decrease in flow, however, is strongly dependent on the chain length of the silanes (factor of 10 at ∼2 nm length). This leads to the conclusion that the observed effect is not caused by sorption driven processes. It is proposed that steric interactions between functional groups and gas molecules lead to increased residence times on the surface and longer molecular trajectories, which, in turn, lead to a decrease in flow. In membrane design, any surface modification should, therefore, make use of functionalizing agents with chain length as short as possible.

Diurnal (24 h) cycle and seasonal variability of cloud fraction retrieved from a Whole Sky Imager over a complex terrain in the Western Ghats and comparison with MODIS

Continuous monitoring of cloud fraction (CF) using a Whole Sky Imager (WSI) equipped with an infrared (IR) camera, play a crucial role in validating satellite data and numerical models. WSI is operated at a high altitude station located in the complex terrain of Western Ghats (WG) of peninsular India from December 2016 to May 2019. CF is retrieved continuously for 24 h at a high temporal resolution (5 min) and a unique time series is constructed for thick, thin, and total cloud cover. The retrieved CF is compared with MODIS (Aqua and Terra satellites) CF during the overpass times over the study area. Good correlation is observed, however, more bias is observed during broken/partial clouds. The biases also arise due to the viewing angles, sensor field of view, and sensitivity of the measurement techniques. The diurnal (24 h) cycle of total CF showed high variability in all the seasons except in monsoon where 90–100% CF is observed throughout the season. The post-monsoon and winter showed high variability due to the occurrence of unusual cyclonic systems in the Arabian Sea as well as in the Bay of Bengal. The temporal monthly mean CF showed significant variability in day and night, with bi-modal and mono-modal distributions in winter and pre-monsoon, respectively during day time, while nights showed mostly flat distribution. Thin CF is also observed in all the months and showed high irregular variability in the range of 2–6%. On a seasonal scale, the observed CF is 50%, 45%, 100%, 60% for winter, pre-monsoon, monsoon and post-monsoon, respectively. The difference in day and night CF is observed only during winter with day CF more than night CF. The study infers that cloud events/characteristics observed on a temporal scale get averaged out on diurnal, monthly, and seasonal scales. When compared with MODIS diurnal and seasonal variability, large biases are observed on a regional scale due to high CF variability, and more importantly, fewer satellite observations representing the day average.

Degradation of pullulan irradiated in hydro-methanolic blends: Influence of cinnamyl alcohol at low absorbed dose of radiation

This study reports on the effects of electron beam radiation on pullulan in both the dry state and hydro-methanolic blends containing cinnamyl alcohol (CA). The radiation chemical yields of scission (G(S)) and crosslinking (G(X)) were determined using Saito’s formalism applied to the evolution of molecular weight (MW) with increasing absorbed dose of radiation. To satisfy the requirements of the statistical treatment, commercially available pullulan was fractionated to obtain a monomodal MW distribution with a dispersity close to 2. The changes in MW profiles were monitored by SEC with differential refractive index and UV detection. The introduction of small quantities of CA in the pullulan blends led to a significant decrease in G(S) and G(X), protecting pullulan against radiation-induced effects likely via energy and electron transfer. In presence of larger amounts of CA, irradiation at higher dose induced an increase in molecular mass with concomitant grafting of the aromatic additive.

Multifunctional transition metal doped titanium dioxide reduced graphene oxide composites as highly efficient adsorbents and photocatalysts

Abstract A series of novel, mesoporous transition metal doped titanium dioxide-reduced graphene oxide composites are synthesized where the dopants were Mn, Co, Ni, Mo, and W. An in-situ synthesis method was used which involves a green, economic, hydrothermal process which can be scaled up easily. The composites show high surface areas (165–245 m2/g) and monomodal pore size distributions with average pore diameters in the range of 3–5 nm. The homogeneous distributions of the dopants are seen in SEM-EDX mapping data. The indirect band gaps of the composite materials are in the range of 2.20–2.48 eV. The composites show excellent dye adsorption activities where 100% adsorption of Rhodamine B occurs within 5 min when Mo–TiO2/rGO composite is used. The adsorbed dye can either be desorbed or photocatalytically degraded and the composite is reusable up to 10 cycles without losing significant activity. Mo–TiO2/rGO composite showed excellent adsorption of both cationic and anionic dyes at neutral pH.

A Method for Retrieving Stratospheric Aerosol Extinction and Particle Size from Ground-Based Rayleigh-Mie-Raman Lidar Observations

We report on the retrieval of stratospheric aerosol particle size and extinction coefficient profiles from multi-color backscatter measurements with the Rayleigh–Mie–Raman lidar operated at the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) in northern Norway. The retrievals are based on a two-step approach. In a first step, the median radius of an assumed monomodal log-normal particle size distribution with fixed width is retrieved based on a color index formed from the measured backscatter ratios at the wavelengths of 1064 nm and 532 nm. An intrinsic ambiguity of the retrieved aerosol size information is discussed. In a second step, this particle size information is used to convert the measured lidar backscatter ratio to aerosol extinction coefficients. The retrieval is currently based on monthly-averaged lidar measurements and the results for March 2013 are discussed. A sensitivity study is presented that allows for establishing an error budget for the aerosol retrievals. Assuming a monomodal log-normal aerosol particle size distribution with a geometric width of S = 1.5, median radii on the order of below 100 nm are retrieved. The median radii are found to generally decrease with increasing altitude. The retrieved aerosol extinction profiles are compared to observations with the OSIRIS (Optical Spectrograph and InfraRed Imager System) and the OMPS-LP (Ozone Mapping Profiling Suite Limb Profiler) satellite instruments in the 60∘ N to 80∘ N latitude band. The extinction profiles that were retrieved from the lidar measurements show good agreement with the observations of the two satellite instruments when taking the different wavelengths of the instruments into account.

Developing formulations for drug follicular targeting: Nanoemulsions loaded with minoxidil and clove oil

Drug vectorization to hair follicles favors skin drug penetration, contributing to the optimization of treatment of diseases as alopecia areata (AA). In this context, this work aimed to develop and characterize nano-sized minoxidil (MXD) formulations to sustained and target drug delivery to hair follicles for the optimization of AA treatment. Nanoemulsions were prepared by ultrasonication. The influence of 3 independent variables at 2 levels and 3 replicates of center point was evaluated, totalizing 11 experimental runs. Three optimized nanoemulsions were studied (NE 5, NE 6 and NE 8). Clove oil and Kolliphor® P188 were selected as oil phase and surfactant, respectively. Optimized nanoemulsions showed monomodal size distributions, mean droplet size of 10 nm with PdI smaller than 0,2 and stability against coalescence at room temperature and relative humidity levels around 50%. Nanoemulsions controlled drug release 2 times more effectively than control sample for at least 6 h, with the predominance of Higuchi release kinetic model. MXD skin penetration from nanoemulsions was raised by more than 9 times, compared with conventional ethanol-based solutions. Follicular drug penetration experiments showed that nanoemulsions containing MXD penetrated into hair follicles more than 26 times more efficiently than control sample, suggesting that the proposed clove oil-based nanoemulsions constitute a promising approach for the topical treatment of alopecia.

Optimization of vertical strain coupling in InAs/GaAs p-i-p quantum dot infrared photodetectors with applied growth strategy

The authors report the optimization of vertically coupled active layers of InAs quantum dots (QDs) grown epitaxially following a unique in-situ growth strategy to achieve controlled strain propagation in subsequent layers resulting in homogenous dot-size distribution. The analysis comprises of bi, tri, penta, hepta and deca coupled layers which have been characterized for their optical properties using photoluminescence spectroscopy (PL) and photoluminescence excitation spectroscopy measurements (PLE) while high resolution X-ray diffraction (HR-XRD) measurements (in-plane and out-of-plane) have been carried out for structural characterization. A gradual shift from bi-modal to monomodal distribution is observed on increasing the coupled layers above five. Activation energies (Ea) calculated from temperature dependent PL results show least thermal quenching for hepta layer coupling which is further corroborated by the strongest room temperature luminescence obtained for the respective sample amongst others. Least out-of-plane compressive strain and also least in-plane tensile strain have been calculated from the HR-XRD results for the hepta layer coupled sample. Furthermore, the in-plane HR-XRD results show minimal amount of In–Ga intermixing for the hepta layer coupling which provides direct evidence of the superior material quality of this heterostructure. Quantum-dot infrared photodetectors (QDIPs) fabricated from the samples have been characterized for their spectral response wherein multiple sharp peaks with narrow full-width at half maxima (FWHM) are obtained in the short-wave infrared (SWIR) region for the hepta layer device, which is absent in other spectra. Also, the response survives up to room temperature (300 K) and stretches in the mid-wave infrared region (MWIR) region (~5 μm). High peak responsivity (Rp = 120.34 A/W) is obtained for the hepta layer device which is much higher than previously reported responsivity values.

Mucoadhesive zein/beta-cyclodextrin nanoparticles for the buccal delivery of curcumin.

Herein, we have developed sprayable dispersions of mucoadhesive nanoparticles (NPs) made of zein, a hydrophobic plant-based protein, for the buccal delivery of curcumin (CUR), a poorly water-soluble polyphenol. NPs were prepared by the liquid-liquid dispersion method using an antisolvent water solution without or with beta-cyclodextrin (CD). NPs were spherical with a monomodal size distribution, a mean size around 140nm and low polydispersity. Excellent colloidal stability of NPs was found at room temperature for up to 1month. CUR entrapment was found to depend mainly on the zein/CUR ratio and related to the ability of CUR to set within hydrophobic pockets in the zein matrix. CD addition generated an increase of NP zeta potential up to +60mV, indicating that positively charged amino acids are prompted to settle on the NP surface. Fluorescence emission spectroscopy indicated that CD interacted with lipophilic amino acids of zein altering interchain interactions and formation of glutamine bridge. Because of zein/CD interactions, mainly occurring at NP periphery, the slowing down of the CUR release rate was observed too. A combination of spectroscopic techniques unequivocally showed that zein NPs strongly interacted with mucin due to electrostatic interactions. Once sprayed on a porcine buccal mucosa, zein/CD NPs securely attached to the tissue resisting repeated washing steps but did not allow CUR transmucosal permeation. Overall, these results point at zein/CD NPs as a novel mucoadhesive platform for the buccal delivery of poorly water-soluble molecules to use as both a food supplement or a drug product to achieve local effects.

Antimicrobial Susceptibility Pattern of Helicobacter heilmannii and Helicobacter ailurogastricus Isolates.

A combined agar and broth dilution method followed by qPCR was used to determine the antimicrobial susceptibility of feline H. heilmannii and H. ailurogastricus isolates. All H. ailurogastricus isolates showed a monomodal distribution of MICs for all the antimicrobial agents tested. For H. heilmannii, a bimodal distribution was observed for azithromycin, enrofloxacin, spectinomycin, and lincomycin. Single nucleotide polymorphisms (SNPs) were found in 50S ribosomal proteins L2 and L3 of the H. heilmannii isolate not belonging to the WT population for azithromycin, and in 30S ribosomal proteins S1, S7, and S12 of the isolate not belonging to the WT population for spectinomycin. The antimicrobial resistance mechanism to enrofloxacin and lincomycin remains unknown (2 and 1 H. heilmannii isolate(s), resp.). Furthermore, H. heilmannii isolates showed higher MICs for neomycin compared to H. ailurogastricus isolates which may be related to the presence of SNPs in several 30S and 50S ribosomal protein encoding genes and ribosomal RNA methyltransferase genes. This study shows that acquired resistance to azithromycin, spectinomycin, enrofloxacin, and lincomycin occasionally occurs in feline H. heilmannii isolates. As pets may constitute a source of infection for humans, this should be kept in mind when dealing with a human patient infected with H. heilmannii.

Monolithic SiC supports with tailored hierarchical porosity for molecularly selective membranes and supported liquid-phase catalysis

Monolithic support materials with the mechanical resistance and thermal conductivity of SiC as well as tunable surface chemistry and textural properties were developed for their use in catalytic membrane reactors. After heat treatment, the extruded SiC monoliths have a monomodal distribution of macropores of a few μm in diameter depending on the particle size of the starting material. A macroporous, defect-free, smoother skin was applied onto the external wall using a solution of sub-micrometer SiC particles. These monoliths with skin could be coated successfully with molecularly selective membranes, and thus have application in membrane reactor processes. Finally, metal oxide nanoparticles were infiltrated into the macropores to modify the surface texture and chemistry, allowing the immobilization of liquid phase catalysts. The resulting multimodal distribution of pore sizes could be tuned by the choice of SiC and oxide particle sizes, number of wash-coats and calcination temperature. Mesopores created between nanoparticles had diameters of roughly 40 % of those of the nanoparticles. Small macropores, between 10−1000 nm, were also created, with bigger size and volume at higher calcination temperatures due to the metal oxide particles contraction. The developed materials were validated as support for PDMS membranes and for continuous gas-phase hydroformylation of 1-butene using Rh-diphosphite catalysts.

Butter production from ozone-treated cream: Effects on characteristics of physicochemical, microbiological, thermal and oxidative stability

The goal of this research was to investigate the effects of the ozone treatment (OT) to raw cream on the physicochemical, microbiological, thermal, and oxidative properties of butter. For this purpose, butter samples were produced from raw cream, which was ozone-treated for 5 (OT-5), 15 (OT-15), 30 (OT-30), and 60 (OT-60) min. The control sample was also produced from non-ozonated raw cream. OT increased firmness, consistency, and fat particle size values of cream. The firmness of butter was between 97 and 380 N. Average fat particle size of samples (D[3.2]) ranged from 22.1 to 30.2 μm, in which OT decreased it. A monomodal fat particle size distribution was determined in all-butter samples. OT decreased b value (yellowness) of butter, and the lowest value was determined in OT-60. The induction time of butter changed from 1.04 (OT-60) – 32.9 h (control). Two melting peaks were determined in butter samples at 14.2–14.6 and 32.3–33 °C. Ozonation for 60 min caused 2.01 log reduction in Staphylococci. Above 15 min, OT completely inactivated Salmonella and yeast-mould. Coliform was not detected in OT-30 and OT-60. The results showed that OT resulted in higher microbiological quality in butter from raw cream.

Incorporating Solution-Processed Mesoporous WO3 as an Interfacial Cathode Buffer Layer for Photovoltaic Applications.

Dextran-templating hydrothermal synthesis of monoclinic WO3 exhibits excellent specific surface area of ∼110 m2/g and a monomodal pore distribution with an average pore diameter of ∼20 nm. Dextran plays a crucial role in generating porosity on WO3. The role of supporting dextran has been investigated and found to be crucial to tune the surface area, porosity, and morphology. The photoluminescence and X-ray photoelectron spectroscopy studies reveal the existence of oxygen vacancies in substoichiometric WO3, which creates localized defect states in WO3 as synthesized through this templating method. The highly mesoporous WO3 has been further explored as an interfacial cathode buffer layer (CBL) in dye-sensitized solar cells (DSSCs) and perovskite solar cells (PSCs). A significantly enhanced photoconversion efficiency has boosted up the performance of the counter electrode used in traditional DSSC (as platinum) and PSC (as carbon) devices by ∼48 and ∼29%, respectively. The electrochemical impedance and incident photon to current conversion efficiency (IPCE) studies were also analyzed in order to understand the catalytic behavior of the WO3 interfacial CBL for both DSSCs and PSCs, respectively. The much higher surface area of WO3 enables rapid electron hopping mechanism, which further benefits for higher electron mobility, resulting in higher short circuit current. Through this study, we were able to unequivocally establish the importance of buffer layer incorporation, which can further help to integrate the DSSC and PSC devices toward more stable, reliable, and enhanced efficiency-generating devices. In spite of this, using WO3 constitutes an important step toward the efficiency improvement of the devices for futuristic photoelectrochromic or self-powered switchable glazing for low-energy adaptive building integration.

Characterization of submicron emulsion processed by ultrasound homogenization to protect a bioactive extract from sea grape (Coccoloba uvifera L.).

In this study, the stability of a submicron emulsion to protect an extract obtained from sea grape fruit (Coccoloba uvifera L.) was evaluated. Extract characterization by MS-HPLC revealed the presence of 3 anthocyanins (cyanidin 3-glucoside, malvidin 3-glucoside, and delphinidin 3-glucoside), the content of total phenols was 263.86 ± 1.86 mg gallic acid equivalent/100 g, with an antioxidant capacity determined by ABTS and DPPH of 128.95 ± 1.00 and 26.18 ± 0.60 μg Trolox equivalents/mL, respectively. A submicron emulsion (0.424 μm) by Ultrasound with monomodal distribution, stable over time and low viscosity (1.94 mPa s) classified as a shear-thinning fluid was obtained. The thermogravimetric analysis (TGA) demonstrated the stability of the C. uvifera extract in the emulsion, which is thermostable (212 °C). These emulsions can be added into a beverage as a nutraceutical, dried for later use as pills or incorporated in foods.

Синтез и исследование структуры наноразмерного оксида меди (II), стабилизированного полиэтиленгликолем

We developed a method for synthesising polyethylene glycol-stabilized copper oxide nanoparticles via a sol-gel process, obtained samples and investigated their structure, morphology and properties. We used photon correlation spectroscopy to establish that the copper oxide nanoparticles feature a monomodal size distribution with the average hydrodynamic radius of a particle being approximately 50 nm irrespective of the stabiliser molar mass. We detected an optical absorption band at 290 nm in all samples. We established that copper oxide samples consist of aggregates formed out of spherical nanoparticles whose diameters lie in the range of 10 to 30 nm. Phase composition analysis of the copper oxide samples revealed that the samples consist of particles featuring a monoclinic structure. We simulated the process of polyethylene glycol interacting with the copper oxide. We show that the most energetically favourable interaction model includes bond formation between the neighbouring intramolecular etheric oxygen atoms and the copper atom

Application of acoustic models for polydisperse emulsion characterization using ultrasonic spectroscopy in the long wavelength regime

Ultrasonic spectroscopy is a technique that often has been used for measuring the particle size distribution in suspensions and emulsions. The ability to analyze concentrated heterogeneous systems and optically opaque samples, without the need for dilution, is the major advantage over alternative technologies, such as light scattering method. Several physical models used to interpret the measured attenuation spectra have been applied considering monodisperse particles. However, the polydisperse particle distributions are found in many practical applications, for example, in crude oil emulsions during droplet coalescence or flocculation. The polydispersity effects are usually important and need to be incorporated into theoretical predictions. For this work, acoustic spectroscopy within the frequency range 6–14 MHz was used to measure the droplet size distribution of water-in-sunflower oil emulsions for a volume fraction range from 10 to 50 % and considering monomodal size distribution. The results obtained from experimental attenuation spectra have been compared with the predictions of acoustic models from simple and multiple scattering, extended multiple scattering, and other simpler models of propagation usually applied to the long wavelength regime. The droplet size distributions from theoretical and experimental attenuation spectra were calculated with a deconvolution algorithm. The size distribution results obtained by ultrasonic spectroscopy showed good agreement with those obtained by laser diffraction analysis. The findings indicate that the methodology employed in this study is suitable for polydisperse particle size characterization for moderate concentrations up to 20 %.