Search Results (31)

The crystallization behavior of polymers affects the structure of aggregated states, which influences the properties of materials. Atomic force microscopy (AFM) is a helpful characterization tool with high spatial resolution at the nanometer-to-micrometer scale and low-destruction imaging capabilities, making it an important means of studying polymer crystallography. This review is intended for scientists in polymer materials and physics, aiming to inspire how the rich applications of AFM can be harnessed to address fundamental scientific questions in polymer crystallization. This paper reviews recent advances in polymer crystallization characterization based on AFM, focusing on its applications in visualizing hierarchical polymer crystal structures (single crystals, spherulites, dendritic crystals, and shish kebab crystals), investigating crystallization kinetics (in situ monitoring of crystal growth), and analyzing structure–property relationships (structural changes under temperature and stress). Finally, we introduce the application of the latest AFM technology in addressing key issues in polymer crystallization, such as single-molecule force spectroscopy (SMFS) and atomic force microscopy–infrared spectroscopy (AFM-IR). As AFM technology advances toward higher precision, greater efficiency, and increased functionality, it is expected to deliver more exciting developments in the field of polymer crystallization. Full article

Manipulating polymer crystallization behavior and structure without altering chemical composition remains a core challenge in polymer crystallography. Molecular weight, as an intrinsic material property, governs the crystallization process from nucleation through growth. Synthetic polymer materials exhibit molecular weight distribution (MWD), resulting in polydisperse polymer chains within one system. This MWD drives distinct crystalline structures, whereas synergistic crystallization behaviors arise among chains of various lengths. MWD yields complex crystallization behaviors. Especially, spatial molecular weight distribution induces novel crystalline textures in polymer materials. Elucidating the crystallization mechanisms is vital for understanding structure-property relationships in polymers. Herein, the recent advances in the various influences of MWD on polymer crystal textures are systematically demonstrated. Full article

Döner kebab, a meat product of Middle-Eastern origin, has gained significant popularity and is now widely consumed across Europe. The recipe varies depending on the area, with beef, turkey, lamb, or chicken being used as main ingredients. The aim of this work was to assess the hygienic-sanitary quality of raw and cooked döner kebabs stored at 4 ± 2 °C for 10 days and at 8 ± 2 °C for the next 20 days or frozen (−18 °C) for one month. One additional aim was to determine the potential growth of Listeria monocytogenes intentionally inoculated in cooked döner kebab during storage at 4 ± 2 °C or freezing. The concentration of Total Viable Count (TVC) and the Enterobacteriaceae of the 100 samples of raw döner kebab were less than 7 log CFU/g and 4 log CFU/g, respectively. Consequently, the samples can be considered acceptable and similar to traditional raw meat. The cooked döner kebab can be considered safe for a period of 30 days, especially from a microbiological point of view, when stored under refrigerated conditions, also taking into account possible thermal abuse. Coagulase Positive Cocci (CPC), Clostridium H₂S⁺, Salmonella spp., and Listeria monocytogenes were never found in any of the samples. After 30 days, the TVC was at the level of 6 log CFU/g and Enterobacteriaceae at less than 4 log CFU/g. The main concern was related to microbial or tissue activity, resulting in an increase in total volatile basic nitrogen (TVB-N) content. However, in the cooked samples, the TVB-N content remained below 40 mg N/100 g at the end of the shelf-life period (32.5 mg N/100 g), which is still considered an acceptable value. In addition, the level of Malondialdehyde (MDA) was found to be within acceptable limits, with a reading of 1.4 nmol/g attained after 30 days. The same product, when frozen and stored at −18 °C, can be considered stable for a minimum of 6 months, both from a microbiological and a physico-chemical point of view. No microbial growth was observed. The TVB-N and the MDA levels increased, but after 6 months, their levels were still acceptable, with values of 19.1 mg N/100 g and 1.2 nmol/g, respectively. These observations demonstrate low protein degradation and lipid oxidation during the shelf-life period. The challenge test showed that Listeria monocytogenes did not grow in döner kebab either when stored at 4 ± 2 °C for 10 days and 8 ± 2 °C for 20 days or when stored at −18 °C for 6 months. The concentration of L. monocytogenes was found to be 5.4 log CFU/g in the refrigerated products and 4.9 log CFU/g in the frozen products. At the end of the shelf-life period, the L. monocytogenes load in both products was lower than the initial concentration that had been added. Finally, the use of air-packaging has been proven to be beneficial to the preservation of the product and maintained its microbiological and physico-chemical properties intact. Despite these good results, future directions could be to investigate different plastic films and packaging such as Modified Atmosphere (MAP), Vacuum (VP), and Sous Vide packaging (SVP). Full article

Out-of-home meals are characterized by poor nutritional quality, and their intake has been linked to adverse health outcomes. Therefore, national and local government initiatives have been implemented in the UK to promote healthier out-of-home meals. However, there is limited evidence of their effectiveness. This study evaluated the fat content and fatty acid profile of takeaway meals from ‘standard’ and from Healthier Catering Commitment (HCC)-approved takeaway outlets. Meals from 14 ‘standard’ and 13 ‘HCC-awarded’ takeaways (74 meals and 26 side dishes) were analyzed for total fat and fatty acid composition. No statistically significant differences in total fat, saturated, and trans fatty acids per 100 g and per portion between HCC and standard meals were observed, except for donner kebabs. Over 70% of all meals contained more than the recommended 30% of daily fat intake from a single meal. Some meals could provide more than 50% of the recommended total fat and SFAs intake. Despite businesses participating in the healthier out-of-home meal initiative, there has not been a significant improvement in the nutritional quality of the meals they offer. Further research to develop effective approaches to support independent takeaway businesses in offering meals with improved nutritional quality is warranted. Full article

In organic optoelectronic devices, the self-assembly behavior of the conjugated polymer poly(3-hexylthiophene) (P3HT) into structured aggregates significantly influences the device’s performance, with processing conditions playing a key role. Incorporating carbon nanotubes (CNTs) into a P3HT solution can form hierarchical supramolecular structures known as nanohybrid shish-kebabs (NHSKs). These structures alter the morphology of polymer aggregates and provide an alternative pathway for improved charge transport in thin film devices. Herein, we investigated the impact of solvent quality using different combinations of chloroform and anisole during the quasi-isothermal crystallization of P3HT:CNTs. We found that NHSKs of different nanowire lengths can be formed through changing solvent quality while maintaining a constant P3HT:SWCNT ratio and a constant SWCNT concentration. Optical absorbance measurements showed that increasing the amount of the good solvent (chloroform) to 10.19% (v/v) reduced the exciton bandwidth by 36.4% compared to the NHSK solution that only contained ~2.37% (v/v). This observation demonstrates the importance of solvent quality and how this processing parameter directly leads to the enhanced crystallization of supramolecular structures. Full article

Doner kebab is a traditional Turkish meat product produced from lamb, beef or poultry meat seasoned with a blend of spices such as salt, black pepper, cumin, thyme and/or sauces. The aim of this study was to determine 16 EU priority polycyclic aromatic hydrocarbons (PAHs) in doner kebabs cooked under four different heating sources (electricity, open gas, wood and charcoal grilling). For this purpose, 200 meat doner and 200 chicken doner kebab samples were obtained randomly from various buffets and restaurants located in Istanbul and analyzed by means of GC-MS. According to the results, benzo[a]pyrene and PAH4 levels, which are important PAH compounds as biomarkers, were significantly higher in chicken doner than in meat doner (p < 0.05). The highest occurrence of benzo[a]pyrene and PAH4 in meat and chicken doner samples was in the charcoal heating source, whereas the lowest occurrence was detected in electric grilling. In terms of all PAH compounds, cooking with an electric heating source caused the formation of fewer PAH compounds in doner kebab samples. Consequently, the fat content of fatty meat products such as doner kebab should be reduced, the contact of fat with the heating source (especially flame) and dripping of fat to the source should be prevented and overcooking of meat should be avoided. Full article

As one of the most widely applied general-purpose plastics, high-density polyethylene (HDPE) exhibits good comprehensive performance. However, mechanical strength limits its wider application. In this work, we introduced the engineering plastic PA6 as a dispersed phase to modify the HDPE matrix and applied multiple shears generated by vibration to the polymer melt during the packing stage of injection molding. SEM, 2D-WXRD and 2D-SAXS were used to characterize the morphology and structure of the samples. The results show that under the effect of a strong shear field, the dispersed phase in the composites can form in situ microfibers and numerous high-strength shish-kebab and hybrid shish-kebab structures are formed. Additionally, the distribution of fibers and high-strength oriented structures in the composites expands to the core region with the increase in vibration times. As a result, the tensile strength, tensile modulus and surface hardness of VIM-6 can reach a high level of 66.5 MPa, 981.4 MPa and 72, respectively. Therefore, a high-performance HDPE product is successfully prepared in this study, which is of great importance for expanding the application range of HDPE products. Full article

The pathway and the lifestyle of known enterococcus species are too complicated. The aim of the present study is to trace the path of pathogenicity of enterococci isolated from seven habitats (Cornu aspersum intestine; Bulgarian yoghurt; goat and cow feta cheese—mature and young, respectively; Arabian street food—doner kebab; cow milk; and human breast milk) by comparing their pathogenic potential. In total, 72 enterococcal strains were isolated and identified by MALDI-TOF, sequencing, and PCR. Hemolytic and gelatinase activity were biochemically determined. PCR was carried out for detection of virulence factors (cylB, esp, gls24, nucl, psaA, agg, gelE, and ace) and antibiotic resistance (erm, ermB, blaZ, vanA, aphA, mefA, gyrA, cat_pIP501, and aac6′-aph2″). Phenotypic antibiotic resistance was assigned according to EUCAST. Eleven representatives of the genus Enterococcus were identified: E. mundtii, E. casseliflavus, E. gilvus, E. pseudoavium, E. pallens, E. malodoratus, E. devriesei, E. gallinarum, E. durans, E. faecium, and E. faecalis. Twenty-two strains expressed α-hemolysis. Thirteen strains had the cylB gene. Only two strains expressed α-hemolysis and possessed the cylB gene simultaneously. Positive amplification for gelE was found in 35% of the isolates, but phenotypic gelatinase activity was observed only in three strains. All isolates showed varying antibiotic resistance. Only E. faecalis BM15 showed multiple resistance (AMP-HLSR-RP). Correlation between genotypic and phenotypic macrolide resistance was revealed for two E. faecalis strains. Full article

The morphology of virgin reactor powder (RP) of high-density polyethylene (HDPE) with M_W = 160,000 g/mol was investigated using DSC, SEM, SAXS, and WAXS methods. The morphological SEM analysis showed that the main morphological units of RP are macro- and micro-shish-kebab structures with significantly different geometric dimensions, as well as individual lamellae of folded chain crystals. A quantitative analysis of an asymmetric SAXS reflection made it possible to reveal the presence of several periodic morphoses in the RP with long periods ranging from 20 nm to 60 nm, and to correlate them with the observed powder morphology. According to the DSC crystallinity data, the thickness of the lamellae in each long period was estimated. Their surface energy was calculated in the framework of the Gibbs—Thompson theory. The presence of regular and irregular folds on the surface of different shish-kebab lamellae was discussed. The percentage of identified morphoses in the RP was calculated. It has been suggested that the specific structure of HDPE RP is due to the peculiarity of polymer crystallization during suspension synthesis in a quasi-stationary regime, in which local overheating and inhomogeneous distribution of shear stresses in a chemical reactor are possible. Full article

In recent years, consumer interest in meat authenticity has increased. Fraudulent claims are most likely to be regarding meat origin, meat substitution, meat processing treatment, and non-meat ingredient additions. This study focuses on the substitution of meat species in processed kebab-like food sales in Poland. The growing popularity of kebab-like foods and the limited number of official inspections of this type of food make this topic interesting. In this study, the results reveal that 60% of the foods analyzed contain an undeclared ingredient or the substitution of an expensive ingredient with a cheaper option. Full article

Staphylococcal food poisoning results from the consumption of food contaminated by staphylococcal enterotoxins. In July 2022, the Turin local health board was notified of a suspected foodborne outbreak involving six children who had consumed döner kebab purchased from a takeaway restaurant. The symptoms (vomiting and nausea) were observed 2–3 h later. A microbiological analysis of the food samples revealed high levels (1.5 × 10⁷ CFU/g) of coagulase-positive staphylococci (CPS). The immunoassay detected a contamination with staphylococcal enterotoxins type B (SEB). The whole genome sequencing of isolates from the food matrix confirmed the staphylococcal enterotoxin genes encoding for type B, which was in line with the SEB detected in the food. This toxin is rarely reported in staphylococcal food poisoning, however, because there is no specific commercial method of detection. The involvement of enterotoxin type P (SEP) was not confirmed, though the corresponding gene (sep) was detected in the isolates. Nasal swabs from the restaurant food handlers tested positive for CPS, linking them to the likely source of the food contamination. Full article

The orientation and dispersion of nanoparticles can greatly influence the conductivity and mechanical properties of nanocomposites. In this study, the Polypropylene/ Carbon Nanotubes (PP/CNTs) nanocomposites were produced using three different molding methods, i.e., compression molding (CM), conventional injection molding (IM), and interval injection molding (IntM). Various CNTs content and shear conditions give CNTs different dispersion and orientation states. Then, three electrical percolation thresholds (4 wt.% CM, 6 wt.% IM, and 9 wt.% IntM) were obtained by various CNTs dispersion and orientations. Agglomerate dispersion (Adis), agglomerate orientation (Aori), and molecular orientation (Mori) are used to quantify the CNTs dispersion and orientation degree. IntM uses high shear to break the agglomerates and promote the Aori, Mori, and Adis. Large Aori and Mori can create a path along the flow direction, which lead to an electrical anisotropy of nearly six orders of magnitude in the flow and transverse direction. On the other hand, when CM and IM samples already build the conductive network, IntM can triple the Adis and destroy the network. Moreover, mechanical properties are also been discussed, such as the increase in tensile strength with Aori and Mori but showing independence with Adis. This paper proves that the high dispersion of CNTs agglomerate goes against forming a conductivity network. At the same time, the increased orientation of CNTs causes the electric current to flow only in the orientation direction. It helps to prepare PP/CNTs nanocomposites on demand by understanding the influence of CNTs dispersion and orientation on mechanical and electrical properties. Full article

Poly(lactic acid) (PLA) microneedles have been explored extensively, but the current regular fabrication strategy, such as thermoforming, is inefficient and poorly conformable. In addition, PLA needs to be modified as the application of microneedle arrays made of pure PLA is limited because of their easy tip fracture and poor skin adhesion. For this purpose, in this article, we reported a facile and scalable strategy to fabricate the microneedle arrays of the blend of PLA matrix and poly(p-dioxanone) (PPDO) dispersed phase with complementary mechanical properties through microinjection molding technology. The results showed that the PPDO dispersed phase could be in situ fibrillated under the effect of the strong shear stress field generated in micro-injection molding. These in situ fibrillated PPDO dispersed phases could hence induce the formation of the shish-kebab structures in the PLA matrix. Particularly for PLA/PPDO (90/10) blend, there are the densest and most perfect shish-kebab structures formed. The above microscopic structure evolution could be also advantageous to the enhancement in the mechanical properties of microparts of PLA/PPDO blend (tensile microparts and microneedle arrays), e.g., the elongation at break of the blend is almost double that of pure PLA while still maintaining the high stiffness (Young’s modulus of 2.7 GPa) and the high strength (tensile strength of 68.3 MPa) in the tensile test, and relative to pure PLA, there is 100% or more increase in the load and displacement of microneedle in the compression test. This could open up new spaces for expanding the industrial application of the fabricated microneedle arrays. Full article

Our attention was focused on the identification of activities affecting air quality, which occur in quick-service restaurants (QSR). The work was based on a measurement study of selected kebab stores in the Polish city of Wrocław. It demonstrated that activities taking place in kebabs altered air quality. The associated changes in air parameters such as temperature, relative humidity, CO₂ concentration, and the content of volatile organic compounds could be detected by utilizing a simple, multi-sensor device. In the measurement data, there were identified multidimensional patterns, which proved to be specific for the following categories of activities: Night Hours, Outlet Preparation, Food Preparation, Operation Hours, and Cleaning. Their occurrence was recognized by pattern recognition methods with a true positive rate greater than 99%. We demonstrated that the recognition may be based on measurements performed in various locations within the kebab store. Although patterns of the individual categories of activities largely varied between kebab stores, a similar performance of recognition was achieved for all restaurants. The obtained results entitled us to conclude that it is possible to detect activities of QSR, which influenced air quality, with the application of sensor technique and pattern recognition. The proposed approach may be applied to this type of object in general. Full article

Common hexaploid oat (Avena sativa L.) is an important global cereal crop. A Moroccan tetraploid sister species, A. magna Murphy et Terrel, was exclusively a wild species until recently. The goal of domestication was to exploit its superior groat-protein content and climatic tolerances. We set up replicated trials of 41 domesticated A. magna lines on eight Moroccan farms during the 2017–2018 and 2018–2019 growing seasons. Twenty traits were measured and analyses of variance detected significant differences among lines. The highest grain yield was at Berrechid in 2017–2018 (63.56 q/ha), with an average annual yield across sites of 43.50 q/ha, the site factor explaining 82% and the genotype-environment interaction explaining 15% of the variability. In the second year, El Kebab recorded the highest yield at 20.03 q/ha over the annual average of 14.78 q/ha. In this second year, the site factor was highly significant, explaining 42.25% of the variation, with the genotype-environment interaction explaining 26.61% of the variability. An additional main effect and multiplicative interaction analysis of the eight two-year trials identified several accessions with good yield stability. Twelve lines exhibited a ASVs ≤ 1.50, with five accessions (A34, A40, A23, A05, A04) exceeding the overall average yield of 29.53 and A34 having the greatest mean grain yield and stability. The versatility and stability of A. magna can provide a sustainable protein source and an economic resource for farmers seeking products that are resilient to climatic instability. Full article