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The Rheology of Hair Products
Published in Laba Dennis, Rheological Proper ties of Cosmetics and Toiletries, 2017
Over the past few years, there has been a trend toward formulating hair products at or below the point of zero charge of hair, which is between pH 3.3 and 4.5 (27). When such a pH range is specified for final hair gel formulations, solvents must be added to the system to ensure clarify of the final product. Lower alcohols are often used for this purpose, but if an “alcohol-free” claim is required, propylene glycol or sorbitol are frequently added as solvents. The latter solvents also act as humectants on the hair. They penetrate the cortex of the hair and help to maintain its moisture content. As a result, the cortex is lubricated against damaging torsional forces during combing. Thus, hair breakage is ameliorated (28).
Clearance, biodistribution, and neuromodulatory effects of aluminum-based adjuvants. Systematic review and meta-analysis: what do we learn from animal studies?
Published in Critical Reviews in Toxicology, 2022
J.-D. Masson, L. Angrand, G. Badran, R. de Miguel, G. Crépeaux
AH is composed of nanoparticles of about 2.2 × 4.5 × 10 nm which spontaneously aggregate forming micron-sized particles with nano-fibrous appearance at electron microscopy. AH point of zero charge (equivalent to the isoelectric point of proteins) is 11.4, therefore, AH shows positive surface charge at pH 7.4 and efficiently binds proteins with negative charge at this pH (e.g. albumin). On the opposite, AP is amorphous and its point of zero charge ranges between 4.5 and 5.5, thus providing a negative surface charge at neutral pH and efficiently binding proteins with positive charge at this pH (e.g. lysozyme) (Seeber et al. 1991; Mold et al. 2016; Gherardi et al. 2019).
Comparative toxicity of three differently shaped carbon nanomaterials on Daphnia magna: does a shape effect exist?
Published in Nanotoxicology, 2018
Renato Bacchetta, Nadia Santo, Irene Valenti, Daniela Maggioni, Mariangela Longhi, Paolo Tremolada
Figure S1a shows the typical round shape of CNP as observed by SEM. The EDX analyses confirmed the purity in carbon content of the used nanopowder: besides the little percentage of oxygen [due to the presence of surface oxides, (Boehm 2002)], and Cu (due to the used grids), only traces of Al and Si were present, these being however 0.16 and 0.42% of the total atomic percentage, respectively (Supplementary Figure S1b). CNP size distribution performed on images taken by TEM (Supplementary Figure S1c) was mainly between 10 and 40 nm (80%) with only a small percentage exceeding 50 nm (9.0%). The mean particle diameter was 28.5 ± 14.3 nm (Supplementary Figure S1d). CNP ζ-potential values were –10.6, –12.9, and –15.9 mV for 1, 10, and 50 mg L−1 suspensions, respectively. Measured values were slightly negative, with little differences among the concentrations, these likely deriving from the different aggregation status, while the small differences of the ζ-potential values from the point of zero charge accounted for the limited stability of the colloidal suspensions. The aggregation status was evaluated by measuring the hydrodynamic diameter as a function of the concentration over time. DLS analyses indicated an increase of the size of the aggregates both as a function of concentration and time. For the highest concentration (50 mg L−1) at 24 h, the scattered light did not show any correlation profile, hampering the measurement of the diffusion coefficient, and consequently the estimation of the size of the aggregates (Supplementary Figure S1e). Measured PAHs concentration in CNPs was 474 μg g−1 (ppm), as sum of 18 compounds, with pyrene (20%), benzo[g,h,i]-perylene (18%), indeno[1,2,3-cd]pyrene (16%) and fluoranthene (13%), as the most abundant ones, followed by benzo(b)fluoranthene + benzo(k)fluoranthene (9%) and acenaphtylene (7%) (Supplementary Figure S1f).
Application of zinc oxide and sodium alginate for biofouling mitigation in a membrane bioreactor treating urban wastewater
Published in Biofouling, 2020
Fatemeh Sokhandan, Maryam Homayoonfal, Fatemeh Davar
X-ray diffraction (XRD) (Advance-D8, Broker Co., Germany) was used to characterize the crystalline structure of the nanoparticles. The crystalline size of the nanoparticles was calculated via the Sherer equation (Trovati et al. 2010). For determining the percentage crystallinity, the area under the crystalline peaks was divided by the total area under the XRD curve (Trovati et al. 2010). To determine the particle size distribution (PSD), an aqueous solution of the samples in deionized water (0.25 wt%) was prepared and then treated by ultrasonic waves to achieve a homogenous dispersion. Then, the PSD was determined via dynamic light scattering (HORIBA Nano Particle Analyzer SZ-100, Northampton, UK). To explore the morphology of the nanoparticles, images were taken via scanning electron microscopy (SEM) (Quanta FEG-450, FEI Co., Hillsboro, USA). Also, to image the cross-section of the membrane, the samples were broken down in liquid nitrogen and dried at room temperature. Next, they were coated with a thin layer of gold in order to make them conductive. For detecting the elements present in the membrane sample, energy-dispersive X-ray spectroscopy (EDS) was performed using an AMETEK EDAX detector (Octane Elite Co., Berwyn, Illinois,USA). In order to recognize the surface topology of the membrane, atomic force microscopy (AFM) was carried out with a DME device (Dual Scope c-26 Co., Braunschweig, Germany) in the contact mode with the scanning rate of 2 Hz and a resolution of 256 × 256. The mechanical properties of the membranes synthesized were determined using a Gotech 216 Universal Testing Machine (GT-TES-2000, Taiwan). For performing the test, membrane samples were cut based on the ASTM-D638 218 standard with the stretching adjusted at the speed of 1 mm min−1. To specify the membrane hydrophilicity, the contact angle between the water drop and the membrane surface was measured based on the method reported by Ma et al. (2017). The point of zero charge (PZC) of the membrane was determined through a drift method (Bayazit and Kerkez 2014). The membrane porosity was calculated by measuring the dry and wet weights of membrane samples with the size and number of membrane pores determined via the method reported by Shukla et al. (2017). The CA, porosimetry, and PZC analyses were repeated three times for each sample and the results were averaged and reported with the assigned standard deviation (SD). To find the antibacterial behavior of the nanoparticles, the membranes were placed in a culture medium containing Hinton-Muller agar. E. coli ATCC 35218 and S. aureus ATCC 25923 were used as models for determining the antibacterial properties. Finally, a zone around the membrane in which no bacteria grew was designated the inhibition zone (Javdaneh et al. 2016). To determine the minimum inhibition concentration (MIC), the bacterial strains were exposed to various concentrations of each sample (10–150 μg ml−1) prepared in 0.1% dimethylsulfoxide (DMSO). Each solution was incubated at 37 °C for 24 h. Following incubation, the absorbance was recorded at 600–620 nm for MIC calculation (Gogoi et al. 2018; Muzammil et al. 2020).