Fast-moving consumer goods (FMCG) industry has long included many appealing essential oils in products to meet consumers’ needs. Among all, the demand for limonene (LM) has recently surged due to its ...broad-spectrum health benefits, with applications in cosmetic, detergent, and food products. However, LM is extremely volatile, hence has often been encapsulated for a longer shelf-life. To date, mostly non-biodegradable synthetic polymers have been exploited to fabricate the microcapsule shells, and the resulting microcapsules contribute to the accumulation of microplastic in the environment. So far, information on LM-entrapping microcapsules with a natural microplastic-free shell and their mechanism of formation is limited, and there is lack of an in-depth characterisation of their mechanical and adhesive properties, which are crucial for understanding their potential performance at end-use applications. The present research aims towards developing safe microcapsules with a core of LM fabricated via complex coacervation (CC) using gum Arabic (GA) and fungally sourced chitosan (fCh) as shell precursors. The encapsulation efficiency (EE) for LM was quantified by gas chromatography (GC) separation method. The morphology of microcapsules was investigated via bright-field optical microscopy and scanning electron microscopy, and their mechanical properties were characterised using a micromanipulation technique. Moreover, the adhesive properties of the resulting microcapsules were studied via a bespoke microfluidic device fitted with a polyethylene-terephthalate (PET) substrate and operating at increasingly hydrodynamic shear stress (HSS). Spherical core-shell microcapsules (EE ~45%) with a mean size of 38 ± 2 μm and a relatively smooth surface were obtained. Their mean rupture force and nominal rupture stress were 0.9 ± 0.1 mN and 2.1 ± 0.2 MPa, respectively, which are comparable to those of other microcapsules with synthetic shells, e.g., urea- and melamine-formaldehyde. It was also found that the fCh-GA complexed shell provided promising adhesive properties onto PET films, leading to a microcapsule retention of ~85% and ~60% at low (≤50 mPa) and high shear stress (0.9 Pa), respectively. Interestingly, these values are similar to the adhesion data available in literature for microplastic-based microcapsules, such as melamine-formaldehyde (50–90%). Overall, these findings suggest that microplastics-free microcapsules with a core of oil have been successfully fabricated, and can offer a potential for more sustainable, consumer- and environmentally friendly applications in FMCGs.
Bacterial adhesion and biofilms on surfaces Garrett, Trevor Roger; Bhakoo, Manmohan; Zhang, Zhibing
Progress in Natural Science/Progress in natural science,
09/2008, Letnik:
18, Številka:
9
Journal Article
Recenzirano
Odprti dostop
Bacterial adhesion has become a significant problem in industry and in the domicile, and much research has been done for deeper understanding of the processes involved. A generic biological model of ...bacterial adhesion and population growth called the bacterial biofilm growth cycle, has been described and modified many times. The biofilm growth cycle encompasses bacterial adhesion at all levels, starting with the initial physical attraction of bacteria to a substrate, and ending with the eventual liberation of cell clusters from the biofilm matrix. When describing bacterial adhesion one is simply describing one or more stages of biofilm development, neglecting the fact that the population may not reach maturity. This article provides an overview of bacterial adhesion, cites examples of how bacterial adhesion affects industry and summarises methods and instrumentation used to improve our understanding of the adhesive properties of bacteria.
Spermiogenesis is the longest phase of spermatogenesis, with dramatic morphological changes and a final step of spermiation, which involves protein degradation and the removal of excess cytoplasm; ...therefore, we hypothesized that macroautophagy/autophagy might be involved in the process. To test this hypothesis, we examined the function of ATG5, a core autophagy protein in male germ cell development. Floxed Atg5 and Stra8− iCre mice were crossed to conditionally inactivate Atg5 in male germ cells. In Atg5
flox/flox
; Stra8− iCre mutant mice, testicular expression of the autophagosome marker LC3A/B-II was significantly reduced, and expression of autophagy receptor SQSTM1/p62 was significantly increased, indicating a decrease in testicular autophagy activity. The fertility of mutant mice was dramatically reduced with about 70% being infertile. Sperm counts and motility were also significantly reduced compared to controls. Histological examination of the mutant testes revealed numerous, large residual bodies in the lumen of stages after their normal resorption within the seminiferous epithelium. The cauda epididymal lumen was filled with sloughed germ cells, large cytoplasmic bodies, and spermatozoa with disorganized heads and tails. Examination of cauda epididymal sperm by electron microscopy revealed misshapen sperm heads, a discontinuous accessory structure in the mid-piece and abnormal acrosome formation and loss of sperm individualization. Immunofluorescence staining of epididymal sperm showed abnormal mitochondria and acrosome distribution in the mutant mice. ATG5 was shown to induce autophagy by mediating multiple signals to maintain normal developmental processes. Our study demonstrated ATG5 is essential for male fertility and is involved in various aspects of spermiogenesis.
Abbreviations: AKAP4: a-kinase anchoring protein 4; ATG5: autophagy-related 5; ATG7: autophagy-related 7; ATG10: autophagy-related 10; ATG12: autophagy-related 12; cKO: conditional knockout; DDX4: DEAD-box helicase 4; MAP1LC3/LC3/tg8: microtubule-associated protein 1 light chain 3; PBS: phosphate-buffered saline; PIWIL2/MILI: piwi like RNA-mediated gene silencing 2; RT-PCR: reverse transcription-polymerase chain reaction; SQSTM1/p62: sequestosome 1; TBC: tubulobulbar complexes; WT: wild type.
•ILs acted as bifunctional catalyst for activating CO2 and the substrate.•CH2Br2 acted as a new dehydrating agent.•Up to 96.9% conversion of amines could be achieved for 7 h at 333.2 K.•DBU could be ...easily recovered and reused for the production of carbamates.
The efficient capture and conversion of carbon dioxide (CO2) has attracted considerable attention for synthesizing valuable chemicals. In this work, we reported an effective method for the synthesis of various carbamates from amines, alcohol, and CO2 in the presence of 1,8-diazabicyclo5.4.0undec-7-ene (DBU). Two pathways were proposed for this reaction process. One pathway was that the protic ionic liquids (ILs), DBUHRO, could activate CO2 to produce DBUHROCO2 at mild conditions. The nucleophilic nitrogen atom of amines attacked the carbon atom of ROCO2− to form the NHCO2−. Another way of the reaction was that the mixture of DBU/amines directly transformed into ILs by exposing to CO2, which was followed by the reaction with electrophile of CH2Br2 to generate the isocyanate at 333.2 K. Moreover, DBU could be easily recovered and reused. This protocol provides a feasible methodology for the production of carbamates and extends the chemical utilization of CO2.
Display omitted
A novel series of halogen free, hydroxyl group containing poly(ionic liquid)s (PILs) was first synthesized from glycerol dimethyl acrylate (GDA) and 1-vinyl imidazole (1-VIM) through ...free radical polymerization, follow by an alkylation step and an ion-exchange procedure to form the final imidazolium hydrogen carbonate heterogenous catalyst poly(HCO3-OH-n). The chemical and physical properties were investigated by varying the monomer ratio between GDA and 1-VIM. Among them, poly (HCO3-OH-2) exhibited the highest catalytic activity for CO2 cycloaddition, with the yield of chloropropene carbonate 90% under mild conditions (80 °C, 0.1 MPa, 12 h, 0.15 g catalyst for 32 mmol epichlorohydrin) in the absence of any cocatalyst, metal or solvent. A range of substrates with good to excellent yields under atmosphere was obtained. The poly(HCO3-OH-n) catalyst is collectable and still remains acceptable catalytic activity after six runs. Finally, a preliminary kinetic is calculated on the basis of poly(HCO3-OH-2) with the activation energy value of 79.5 kJ·mol−1. This study highlights that the poly(HCO3-OH-n) enable to reach efficient CO2 conversion under mild conditions.
Microneedles, including dissolvable ones made from biocompatible and biodegradable materials, have been widely studied and can potentially be used for transdermal drug delivery, disease diagnosis ...(sampling), skin care, etc. Characterizing their mechanical properties is essential, as being mechanically strong enough to pierce the skin barrier is one of the most fundamental and crucial requirements for them. The micromanipulation technique was based on compressing single microparticles between two flat surfaces to obtain force and displacement data simultaneously. Two mathematical models had already been developed to calculate the rupture stress and apparent Young's modulus, which can identify variations of these parameters in single microneedles within a microneedle patch. In this study, a new model has been developed to determine the viscoelasticity of single microneedles made of hyaluronic acid (HA) with a molecular weight of 300 kDa loaded with lidocaine by using the micromanipulation technique to gather experimental data. The modelling results from the micromanipulation measurements suggest that the microneedles were viscoelastic and their mechanical behaviour was strain-rate dependent, which implies that the penetration efficiency of viscoelastic microneedles can be improved by increasing their piercing speed into the skin.
The adsorption and activation of triplet O2 on the surface of nitrogen-doped carbon nanotube (NCNT) with different diameter and length were investigated. It was found that, rather than the ...unfavorable adsorption on normal carbon nanotube (CNT), the adsorption of O2 on NCNT was obviously exothermic and the electron transition of O2 happened in the adsorption process. The oxygen adsorbed on NCNT showed an interesting electron configuration which was similar to the active oxygen anion. The spin density, charge, and bond length of O2 changed with the size of NCNT. In combination with the recent results reported by Dai et al. (Science, 2009, 323, 760), it is reasonable to believe that these NCNTs should be a potential metal-free catalyst. The results presented here should be useful for designing and developing effective catalyst based on NCNT.
An effective method using gold(i) isocyanide complexes as catalysts for the transformation of various alkynes to the corresponding ketones is successfully developed. The hydration process proceeds ...smoothly at room temperature with quite high yield (up to 99%). The catalytic center is the isocyanide-Au(i) super(+) cation. Further theoretical research reveals a direct hydration mechanism by H sub(2)O, and the rate-determining step has an energy barrier of 23.7 kcal mol super(-1). These results show a good example to reduce unnecessary steps and achieve milder reaction conditions at the same time for the hydration of alkynes.
The successful implementation of Vessel Traffic Services (VTS) relies heavily on human decisions. With the increasing development of maritime traffic, there is an urgent need to provide a sound ...support for dynamic risk appraisals and decision support. This research introduces a cellular automata (CA) simulation-based modelling approach the objective of which is to analyze and evaluate real-time maritime traffic risks in port environments. The first component is the design of a CA model to monitor ships’ behavior and maritime fairway traffic. The second component is the refinement of the modelling approach by combining a cloud model with expert knowledge. The third component establishes a risk assessment model based on a fuzzy comprehensive evaluation. A typical scenario was experimentally implemented to validate the model’s efficiency and operationality.
Micromanipulation is a powerful technique to measure the mechanical properties of microparticles including microcapsules. For microparticles with a homogenous structure, their apparent Young's ...modulus can be determined from the force versus displacement data fitted by the classical Hertz model. Microcapsules can consist of a liquid core surrounded by a solid shell. Two Young's modulus values can be defined, i.e., the one is that determined using the Hertz model and another is the intrinsic Young's modulus of the shell material, which can be calculated from finite element analysis (FEA). In this study, the two Young's modulus values of microplastic-free plant-based microcapsules with a core of perfume oil (hexyl salicylate) were calculated using the aforementioned approaches. The apparent Young's modulus value of the whole microcapsules determined by the classical Hertz model was found to be
= 0.095 ± 0.014 GPa by treating each individual microcapsule as a homogeneous solid spherical particle. The previously obtained simulation results from FEA were utilised to fit the micromanipulation data of individual core-shell microcapsules, enabling to determine their unique shell thickness to radius ratio (
)
= 0.132 ± 0.009 and the intrinsic Young's modulus of their shell (
= 1.02 ± 0.13 GPa). Moreover, a novel theoretical relationship between the two Young's modulus values has been derived. It is found that the ratio of the two Young's module values (
/
) is only a function on the ratio of the shell thickness to radius (
) of the individual microcapsule, which can be fitted by a third-degree polynomial function of
. Such relationship has proven applicable to a broad spectrum of microcapsules (i.e., non-synthetic, synthetic, and double coated shells) regardless of their shell chemistry.
PDF
