Abstract We have been investigating the physical properties of simple Gemini surfactant with short linker chains using conductivity, dynamic light scattering (DLS) and isothermal titration ...calorimetry (ITC). The surfactants used here have the general formula (CH 3 (CH 2 ) 11 )(CH 3 ) 2 -N + -(CH 2 ) n -N + (CH 3 (CH 2 ) 11 )(CH 3 ) 2 ·Br 2 , where n = 2, 3 or 4 and, as such, are designated as 12-2-12, 12-3-12 and 12-4-12. The ultimate goal of this work was to determine the enthalpy of demicellization using ITC. To determine the proper experimental conditions, it was necessary to first determine the critical micelle concentration (cmc) using conductivity and the size of the formed micelles using DLS for each surfactant. The results indicate a number of linear relationships between the number of carbons in the linker and certain physical properties such as cmc and Δ G mic as determined by conductivity studies. As expected, demicellization is enthalpically unfavorable but entropically driven. Linear relationships are also observed between the number of linker carbons and some thermodynamic properties as determined by ITC. Graphical abstract
An efficient biosynthesis process for the rapid production of nanoparticles would enable the development of a “microbial nanotechnology” for mass-scale production. In the present research, biological ...silver nanoparticle was synthesized extracellularly by using the fungus,
Trichoderma longibrachiatum
, where the cell filtrate of the fungus was used as a reducing and stabilizing agent in the process of nanoparticle synthesis. Different physical parameters such as fungal biomass concentration (1, 5, 10, 15, and 20 g), temperature (25, 28, and 33 °C), incubation time (0–120 h), and agitation (shaken or not shaken) were investigated, in order to determine the optimal conditions for nanoparticle biosynthesis. The stability and antifungal properties of the synthesized silver nanoparticles (AgNPs) were also determined. Data revealed that a combination of 10 g fungal biomass, a reaction temperature of 28 °C, a 72-h incubation time, and without shaking were the optimum conditions for the synthesis of the silver nanoparticles. Visual observation of brown color is an indication of silver nanoparticle production. UV–vis spectroscopy showed maximum absorption at 385 nm with the optimum conditions. Transmission electron microscopy (TEM) revealed the formation of monodispersed spherical shape with a mean diameter of 10 nm. Fourier transformation infrared (FTIR) showed bands at1634.92 and 3269.31 cm
−1
. Dynamic light scattering (DLS) supported that the
Z
-average size was 24.43 and 0.420 PdI value. Zeta potential showed − 19.7 mV with a single peak. The AgNPs synthesized through this biosystem approach were relatively stable up to 2 months after synthesis. The use of AgNPs as antifungal led to significant reductions in the number of forming colonies for many plant pathogenic fungi, with efficiencies reaching up to 90% against
Fusarium verticillioides
,
Fusarium moniliforme
,
Penicillium brevicompactum
,
Helminthosporium oryzae
, and
Pyricularia grisea
. However, further research should be carried out in order to determine the toxic effect of AgNPs before mass production and use of agricultural applications.
The present study reports a comparison on aggregation behaviour of PEO-PPO star block copolymers Tetronics® 1304 and 1307 in the presence of toluene, phenol and methyl phenols viz. o-cresol, ...m-cresol, p-cresol. These organic compounds are frequently used in plastics, dyes, pesticides and pharmaceutical industries. Star block copolymers, Tetronics®, are used to solubilise different poorly aqueous soluble substances for a long time in different industrial applications. So, to understand the influence of these solvents on the micellar dimensions of star block copolymers T1304 and T1307 with varied hydrophobicity, dynamic light scattering (DLS) and small angle neutron scattering (SANS) techniques are used. The result reveals the presence of spherical micelles for both the copolymers. However, a significant growth in micellar size is observed with continuous addition of these organic solvents as additives. Maximum micellar growth is observed in the presence of o-cresol and minimum in the presence of toluene.
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Using the Computable General Equilibrium of Land Use Change (CGELUC) and Dynamics of Land System (DLS) models, we simulated land-use structures and patterns in Shandong Province in 2025 under three ...scenarios: baseline, resource consumption, and green development. Compared with the situation in 2015, a slight decrease in grassland, cultivated, and unused land was evident under the green development scenario. Forest land cover remained basically unchanged, whereas water bodies and construction land increased slightly. Under the baseline and resource consumption scenarios, all of the above land-use types showed a decreasing trend apart from construction land, which rapidly increased. Changes in the land-use allocation pattern demonstrated overall consistency and local differences under these scenarios. Among them, most changes in construction and cultivated land occurred around cities, with changes in forests and grassland mainly distributed in the central and northeastern regions. Changes in water bodies and unused land mainly occurred in the northern Yellow River basin and in northeastern coastal areas. Local differences were evident under the green development scenario, with conversion of a small amount of cultivated land in the central region into forests and grassland, and transformation of a small area of cultivated land in the northeastern coastal area into water bodies. The study's findings provide a scientific projection of competitive land-use relations in Shandong Province over the next decade under different land expropriation price and regulation scenarios, which can guide policy formulation and the selection of pathways for achieving sustainable regional development.
•We applied integrated models to identify sustainable modes of land development.•We simulated future land-use structures and patterns under different scenarios.•Green development protects ecologies and limits expansion of construction land.
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•Glucosamine binds to gold nanoparticles obtained from laser ablation in liquid.•Aggregation of glucosamine at 10 mM concentration causes new UV–VIS band at 625 nm.•SERS spectra of ...glucosamine in clean gold colloid were obtained for 0.1 mM and 1 mM glucosamine concentrations.•Strongest SERS bands are at 1563, 1586 and 1652 cm−1 (fron C-NH3+ bending modes), at 1165 cm−1 (C-N stretching coupled with C-C stretching motion) and at 1075 cm−1 (C-O stretching coupled with ring C-C stretching mode)
The binding of glucosamine to gold in water solutions of glucosamine hydrochloride mixed with clean colloidal gold nanoparticles obtained by laser ablation in liquid was studied using surface-enhanced Raman scattering (SERS), dynamic light scattering (DLS) and UV–VIS spectroscopy. The purpose of this study was to establish whether the binding of charged aminogroup to gold nanoparticles (AuNPs) is taking place, and if it does, how can it be identified by means of SERS.
The average size of dried gold nanoparticles was (20 ± 4) nm determined by averaging the sizes observed in transmission electron microscopy micrographs, which is smaller than the average size of gold nanoparticles in water solution as determined by DLS: (52 ± 2) nm. Upon adding the glucosamine solutions to gold colloid, average hydrodynamic diameter of ions was slightly larger for 0.1 mM glucosamine solution (55 ± 2 nm), while it increased to (105 ± 22) nm in the case of 1 mM solution, and was (398 ± 54) nm when 10 mM glucosamine solution was added.
Most prominent Raman bands observed both for 0.1 mM and 1 mM glucosamine solutions were located at 1165 cm−1, 1532 and 1586 cm−1 and assigned to C-N coupled with C-C stretching, and C-NH3+ deformation angles bending. In SERS spectrum of 1 mM GlcN+ solution, two strong bands at 999 and 1075 cm−1 were found and attributed to C-Oring stretching coupled with C-NH3+ bending (999 cm−1) and to dominantly C-O stretching vibration. The differences in SERS spectra are attributed to different number of glucosamine molecules that attach to gold nanoparticles and their orientation with respect to the metal particle surface, partly due to presence of beta anomers protonated at anomeric oxygen position. The assignment of glucosamine bands was further corroborated by comparison with vibrational spectra of alpha and beta glucose and of polycrystalline powder of glucosamine hydrochloride. For all three substances comprehensive calculation of vibrational density of states was conducted using density functional theory. Benchmark bands for polycrystalline glucose anomers distinction are 846 and 915 cm−1 for alpha glucose, and 902 cm−1 for beta glucose. However, the bands observed in SERS spectra of 0.1 mM glucosamine solution at 831, 899, and 946 cm−1 or in 1 mM solution at 934 cm−1 cannot be easily identified as belonging either to alpha or beta glucosamine anomer, due to complexity of atomic motions involved. The identification of vibrational bands associated with –CNH3+ group will aid SERS studies on amino acids, especially in cases when several atomic groups could possibly bind to AuNPs.
The accurate determination of Hamaker constant of humus is the basis for understanding the colloidal behavior of humus in environment. However, the determination of the Hamaker constant of humus is ...still a challenge because of its low value in Hamaker constant. In this study, a method for determining the Hamaker constant of humus with dynamic light scattering (DLS) technique has been established. Firstly, the Hamaker constants of the mixture colloids of “humic acid (HA) + montmorillonite (Mont, with known high Hamaker constant)” with different HA/Mont ratios were determined by DLS technique. Secondly, the mathematic relationship of the Hamaker constant (A) of the mixture colloid and HA content (y with percentage) was established, and it was A = 13.32 × 10−20y−0.507 J. From which, finally, the Hamaker constant of HA (when y = 100) was obtained and it was 1.29 × 10−20 J. The validity of the obtained Hamaker constant of HA was confirmed by the comparison of the calculated CCC by adopting the obtained Hamaker constant of HA and the experimentally determined CCC by DLS. The established method in this study can be applied to the Hamaker constant determination of other nano-sized organic materials by DLS.
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Dynamic Laser Speckle (DLS) images are processed under different computational methods to extract activity map and numerical information of the activity present in the sample. Some existing methods ...include GD, Fujii, which provides the activity map, and IM, AVD, which numerically quantifies the activity. However, there is hardly a method that simultaneously provides speckle activity map linked with a numerical value. It takes much time to process with different methods for graphical and numerical information about the speckle activity. In this work, a new method has been proposed, which provides the speckle activity map associated with a numerical information for DLS analysis. We have found that both the graphical and numerical results obtained from the proposed method are in good agreement with other existing methods. In another experiment of Biospeckle imaging of papaya leaf subjected under different PAR intensities, we have found that the average frequency (represents the biospeckle activity) of papaya leaf increases as the photosynthesis rate increases. Furthermore, this method takes less computational time (0.70 ± 0.021 s) to process data compared to GD (1.89 ± 0.012 s), Fujii (0.75 ± 0.042 s), and IM & AVD (1.1 ± 0.017 s).
A pyrene based probe (E)-N’-(pyren-1-ylmethylene)thiophene-2-carbohydrazide (PTH), was synthesized and characterized by IR, NMR and HRMS spectroscopic tools. The probe exhibited aggregation induced ...emission enhancement (AIEE) in binary solvent mixture (ACN/water) on increasing water fraction and displayed bright yellow emission in solid state. Fluorescence spectroscopy, time resolved fluorescence and DLS analysis have been exploited to gain insight into the mechanism. These results indicated an enhancement in quantum yield and average lifetime with an increase in water content. In addition to intriguing AIEE property, PTH demonstrated excellent selectivity and sensitivity for F− over various other anions. A plausible mechanism for interaction of the probe with F− has been proposed on the basis of 1H NMR titration, absorption spectra and DFT study. The recognition process was found to be driven by the high electronegativity of F− leading hydrogen bonded adduct followed by deprotonation of PTH. Instant naked eye response along with commendable detection limit (2.02 × 10−7 M) and binding constant (6.18 × 104 M−1) increased the pertinency of the probe.
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•A novel pyrene-thiophene based probe has been synthesized and characterized.•The probe offers a remarkable AIEE and fluoride sensing behavior.•UV–vis, fluorescence, DLS and DFT measurements supported AIEE property.•Interesting color tuning AIEE with increasing water fraction.•Low detection limit for F− sensing and paper strip test increase its practical utility.
In this work, the potential of several techniques commonly used in research studies for TiO2 nanoparticles' (NPs) characterization was evaluated for the implementation in routine analysis. Namely, ...Dynamic Light Scattering (DLS), single-particle mode Inductively Coupled Plasma Mass Spectrometry (spICP-MS) and Asymmetrical Flow Field-Flow Fractionation coupled to Multi Angle Light Scattering and (single particle) Inductively-Coupled Plasma Mass Spectrometry (AF4-MALS-(sp)ICP-MS) were assessed for this purpose. Electron Microscopy was also used to confirm the validity of results and to obtain information about the shape of the particles. Each instrument was optimized according to routine analysis criteria using reference materials for instrument performance and quality assurance. Then, the methodology was applied to two types of samples of consumer products (sunscreens and sugar-coated chocolate candies), where particle size and concentration obtained by each technique were discussed. Results indicated that TiO2 particles were found in both samples. AF4-MALS-ICP-MS and spICP-MS were powerful tools to characterize TiO2 NPs in real samples, with spICP-MS being more adapted to routine analysis. DLS and electron microscopy provided comparable results for the particle size. The studied sunscreen complied with the European regulation (No 1223/2009) in relation with NPs because the particle size found for TiO2 was in the range 80–110 nm and the reference to “nano” required is present in the label of the product. Sugar-coated chocolate candies may contain NPs according to DLS and AF4-MALS-ICP-MS results, but particles larger than 100 nm were found by spICP-MS.
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•Study of potential techniques for nanoparticles routine analysis was done.•Analysis TiO2 particles has been performed in consumer products.•DLS, SP-ICP-MS and AF4-MALS-(sp)ICP-MS techniques have been applied and compared.•TiO2 nanoparticles were found in sunscreen labeled as ‘nano’.•TiO2 particles were also found in chocolate candies non-labeled as ‘nano’.
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