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1.
Molecules ; 29(15)2024 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-39124929

RESUMO

There is considerable interest in the use of essential oils for food preservation, but their effect on the aroma profile of a product is poorly understood. This study investigated the effect of thyme essential oil (EO) addition at increasing concentrations (0.005, 0.01, 0.02, and 0.03% v/w) on the volatile compound composition of vacuum-packed minced turkey meat after storage for 8 days at 1-2 °C. The aroma profile of the meat was determined using the HS-SPME/GCMS (headspace solid-phase microextraction/gas chromatography-mass spectrometry) method. The results were also analysed by PCA (principal component analysis). The addition of thyme EO had a modifying effect on the aroma profile of meat-derived components, e.g., the formation of benzeneacetaldehyde, benzyl alcohol, 4,7-dimethylbenzofuran, hexathiane, hexanal, and 1-hexanol was reduced and the appearance of 9-hexadecenoic acid was observed in the stored samples. The increase in EO concentration affected the levels of its individual components in the meat headspace in different ways. In terms of fat rancidity indices, even a 0.005% addition of this essential oil significantly reduced the peroxide value. Quantitative descriptive analysis (QDA) showed that the addition of thyme EO reduced or masked the intensity of unpleasant odours associated with meat spoilage. In the aroma analysis, the turkey with 0.02% v/w EO scored highest, and pleasant citrus notes were found.


Assuntos
Conservação de Alimentos , Odorantes , Óleos Voláteis , Thymus (Planta) , Perus , Óleos Voláteis/química , Thymus (Planta)/química , Animais , Vácuo , Odorantes/análise , Conservação de Alimentos/métodos , Cromatografia Gasosa-Espectrometria de Massas , Microextração em Fase Sólida , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/química , Embalagem de Alimentos , Carne/análise , Armazenamento de Alimentos/métodos
2.
Sci Rep ; 14(1): 18522, 2024 08 09.
Artigo em Inglês | MEDLINE | ID: mdl-39122821

RESUMO

One major limitation of effective vaccine delivery is its dependency on a robust cold chain infrastructure. While Vesicular stomatitis virus (VSV) has been demonstrated to be an effective viral vaccine vector for diseases including Ebola, its -70 °C storage requirement is a significant limitation for accessing disadvantaged locations and populations. Previous work has shown thermal stabilization of viral vaccines with a combination of pullulan and trehalose (PT) dried films. To improve the thermal stability of VSV, we optimized PT formulation concentrations and components, as well as drying methodology with enhanced vacuum drying. When formulated in PT films, VSV can be stored for 32 weeks at 4 °C with less than 2 log PFU loss, at 25 °C with 2.5 log PFU loss, and at 37 °C with 3.1 log PFU loss. These results demonstrate a significant advancement in VSV thermal stabilization, decreasing the cold chain requirements for VSV vectored vaccines.


Assuntos
Glucanos , Trealose , Trealose/química , Glucanos/química , Vácuo , Vetores Genéticos , Dessecação/métodos , Vacinas Virais/química , Vesiculovirus/genética , Animais , Temperatura
3.
Molecules ; 29(15)2024 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-39124880

RESUMO

Vacuum-Assisted Sorbent Extraction (VASE) is a novel extraction technique that uses vacuum to facilitate the transfer of volatile compounds from the matrix to the sorbent. This technique was explored for extraction of volatiles from cape gooseberry fruit, for both qualitative and quantitative analyses. Selected extraction parameters were tested: sample size, extraction temperature and time, influence of tissue disintegration on release of volatiles, and also addition of Ag+1 ions in the form of AgNO3 to stop enzymatic formation of volatile compounds. For selected conditions (10 g sample, extraction for 30 min. at 40 °C of volatiles from blended fruit) quantitative aspects were explored. Twenty-two compounds of cape gooseberry were tested. The method was characterized with a very good linearity in a range of 10-5000 µg/kg and good reproducibility. The experiments proved the usefulness of VASE in both volatile profiling and quantitative analyses of cape gooseberry and in prospective other fruit.


Assuntos
Frutas , Physalis , Compostos Orgânicos Voláteis , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/isolamento & purificação , Compostos Orgânicos Voláteis/química , Physalis/química , Frutas/química , Vácuo , Reprodutibilidade dos Testes , Extratos Vegetais/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Extração em Fase Sólida/métodos
4.
Methods Mol Biol ; 2841: 157-164, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39115774

RESUMO

Agrobacterium-mediated transient expression is a flexible and efficient technique for introducing genes into plants, allowing for rapid and temporary gene expression. Agroinfiltration of Arabidopsis seedlings is a newly developed Agrobacterium-based transient expression system. The expression of target genes and the localization of relevant proteins can be observed within 3 days using this method. In this chapter, we present the detailed protocol for transient transformation in Arabidopsis thaliana seedlings utilizing vacuum infiltration of Agrobacterium. This procedure enables rapid and temporary gene expression by introducing exogenous DNA into Arabidopsis seedlings, particularly in easily accessible tissues such as cotyledons. This protocol provides a detailed description of experimental procedures, including Arabidopsis seedlings cultivation, the preparation of Agrobacterium suspensions, and subsequent steps leading to confocal microscope observation. Through this protocol, researchers can efficiently investigate gene function and subcellular localization in Arabidopsis cotyledons within 8 days in total.


Assuntos
Arabidopsis , Plântula , Arabidopsis/genética , Arabidopsis/metabolismo , Plântula/genética , Plântula/metabolismo , Plântula/crescimento & desenvolvimento , Vácuo , Cotilédone/genética , Cotilédone/metabolismo , Transformação Genética , Expressão Gênica , Plantas Geneticamente Modificadas/genética , Agrobacterium/genética , Regulação da Expressão Gênica de Plantas , Microscopia Confocal
5.
AAPS J ; 26(5): 89, 2024 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-39150583

RESUMO

A non-invasive capacitance instrument was embedded in the base of a vacuum-drying tray to monitor continuously the residual amount of solvent left in a pharmaceutical powder. Proof of concept was validated with Microcrystalline Cellulose laced with water, as well as water/acetone mixtures absorbed in a spray-dried Copovidone powder. To illustrate the role of impermeability of the base, we derive a model of vapor sorption that reveals the existence of a kinetic limit when solids are thinly spread, and a diffusion limit with greatly diminished effective diffusivity at large powder thickness. By monitoring the residual solvent content of powders, this new in situ technique offers advantages over indirect methods like mass spectrometry of vapor effluents, but without complications associated with probe fouling. To prescribe design guidelines and interpret signals, we model the electric field shed by the probe when a powder holds variable solvent mass fraction in the vertical direction.


Assuntos
Celulose , Pós , Solventes , Solventes/química , Vácuo , Celulose/química , Celulose/análise , Pirrolidinas/química , Pirrolidinas/análise , Compostos de Vinila/química , Água/química , Dessecação/métodos , Acetona/análise , Acetona/química , Difusão , Cinética
6.
Phys Chem Chem Phys ; 26(27): 18943-18952, 2024 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-38952218

RESUMO

The hallmark of amyloidosis, such as Alzheimer's disease and Parkinson's disease, is the deposition of amyloid fibrils in various internal organs. The onset of the disease is related to the strength of cytotoxicity caused by toxic amyloid species. Furthermore, amyloid fibrils show polymorphism, where some types of fibrils are cytotoxic while others are not. It is thus essential to understand the molecular mechanism of cytotoxicity, part of which is caused by the interaction between amyloid polymorphic fibrils and cell membranes. Here, using amyloid polymorphs of hen egg white lysozyme, which is associated with hereditary systemic amyloidosis, showing different levels of cytotoxicity and liposomes of DMPC and DMPG, changes in the secondary structure of the polymorphs and the structural state of phospholipid membranes caused by the interaction were investigated using vacuum-ultraviolet circular dichroism (VUVCD) and Laurdan fluorescence measurements, respectively. Analysis has shown that the more cytotoxic polymorph increases the antiparallel ß-sheet content and causes more disorder in the membrane structure while the other less cytotoxic polymorph shows the opposite structural changes and causes less structural disorder in the membrane. These results suggest a close correlation between the structural properties of amyloid fibrils and the degree of structural disorder of phospholipid membranes, both of which are involved in the fundamental process leading to amyloid cytotoxicity.


Assuntos
Amiloide , Dicroísmo Circular , Muramidase , Fosfolipídeos , Muramidase/química , Muramidase/metabolismo , Amiloide/química , Fosfolipídeos/química , Animais , Estrutura Secundária de Proteína , Dimiristoilfosfatidilcolina/química , Fosfatidilgliceróis/química , Lipossomos/química , Galinhas , Vácuo
7.
Ultrason Sonochem ; 108: 106980, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38981338

RESUMO

To obtain high-quality cherry products, ultrasound (US) combined with five chemical pretreatment techniques were used on cherry prior to radio frequency vacuum drying (RFV), including carboxymethyl cellulose coating (CMC), cellulase (CE), ethanol (EA), isomaltooligosaccharide (IMO), and potassium carbonate + ethyl oleate (PC + AEEO). The effect of different pretreatments (US-CMC, US-CE, US-EA, US-IMO, US-(PC + AEEO)) on the drying characteristics, quality properties, texture, and sensory evaluation of cherries was evaluated. Results showed that the dehydration time and energy consumption were decreased by 4.17 - 20.83 % and 3.22 - 19.34 %, respectively, and the contents of individual sugars, soluble solid, total phenolics (TPC), natural active substances, total flavonoids (TFC), and antioxidant properties (DPPH, ABTS and FRAP) were significantly increased after US combined with five chemical treatments (P < 0.05). Moreover, the pretreatment played important role in improving texture properties and surface color retention in the dried cherries. According to the sensory evaluation analysis, the dehydrated cherries pretreated with US-CMC exhibited the highest overall acceptance, texture, crispness, color, and sweet taste showed lower off-odor, bitter taste and sour taste compared to control and other pretreatments. The findings indicate that US-CMC pretreatment is a promising technique for increasing physicochemical qualities and dehydration rate of samples, which provides a novel strategy to processing of dried cherry.


Assuntos
Dessecação , Prunus avium , Vácuo , Dessecação/métodos , Prunus avium/química , Ondas Ultrassônicas , Antioxidantes/química , Ondas de Rádio , Manipulação de Alimentos/métodos , Qualidade dos Alimentos , Paladar , Fenóis/análise , Fenóis/química
8.
Best Pract Res Clin Gastroenterol ; 70: 101927, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-39053980

RESUMO

Endoscopic vacuum therapy (EVT) is an established technique for the treatment of rectal wall defects and especially anastomotic leaks. A wide range of EVT devices, both handmade and commercially available, allow for their successful placement even in small defects and difficult localizations. Reported success rates range between 85 and 97 %, while periintervenional morbidity is low and major adverse events are very rare. EVT has proven its effectiveness in the lower gastrointestinal tract and is now considered first line treatment for pelvic anastomotic leaks. This narrative review summarizes the current literature on EVT in the lower gastrointestinal tract, focusing on its indications, technical aspects and results, and offers tips and tricks for its clinical applications.


Assuntos
Fístula Anastomótica , Humanos , Fístula Anastomótica/terapia , Fístula Anastomótica/etiologia , Vácuo , Resultado do Tratamento , Endoscopia Gastrointestinal/métodos , Endoscopia Gastrointestinal/instrumentação , Reto/cirurgia , Tratamento de Ferimentos com Pressão Negativa/métodos , Tratamento de Ferimentos com Pressão Negativa/instrumentação
9.
Best Pract Res Clin Gastroenterol ; 70: 101901, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-39053979

RESUMO

BACKGROUND: Transmural defects in the upper gastrointestinal (GI) tract, such as anastomotic leakage and oesophageal perforations, are associated with significant morbidity and mortality risks. Endoscopic vacuum therapy (EVT) is an efficient and safe treatment option for these patients. With the growing use of EVT in the upper GI tract, it is important to share expertise on the topic. AIM: This review explores the emerging role of endoscopic vacuum therapy (EVT) as treatment for transmural defects in the upper GI tract. An overview of the mechanism and procedures, outcomes in current literature and challenges of implementation and application are discussed. CONCLUSION: EVT exhibits great efficacy and safety for the treatment of transmural defects in the upper GI tract. Current use of EVT is mostly experience-based, emphasizing the importance of sharing expertise and performing research to unlock its full potential.


Assuntos
Endoscopia Gastrointestinal , Humanos , Endoscopia Gastrointestinal/instrumentação , Endoscopia Gastrointestinal/métodos , Fístula Anastomótica/terapia , Fístula Anastomótica/etiologia , Resultado do Tratamento , Perfuração Esofágica/terapia , Perfuração Esofágica/etiologia , Perfuração Esofágica/cirurgia , Vácuo , Trato Gastrointestinal Superior/cirurgia , Trato Gastrointestinal Superior/diagnóstico por imagem
10.
J Appl Microbiol ; 135(7)2024 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-38955370

RESUMO

AIMS: This study aims to evaluate the storage stability of the freeze-dried recombinant Lactococcus lactis NZ3900-fermented milk powder expressing K-ras (Kristen rat sarcoma viral oncogene homolog) mimotopes targeting colorectal cancer in vacuum packaging. METHODS AND RESULTS: The freeze-dried L. lactis-fermented milk powder stored in 4-ply retortable polypropylene (RCPP)-polyamide (PA)-aluminium (AL)-polyethylene terephthalate (PET) and aluminium polyethylene (ALPE) was evaluated throughout 49 days of accelerated storage (38°C and 90% relative humidity). The fermented milk powder stored in 4-ply packaging remained above 6 log10 CFU g-1 viability, displayed lower moisture content (6.1%), higher flowability (43° angle of repose), water solubility (62%), and survivability of L. lactis after simulated gastric and intestinal digestion (>82%) than ALPE packaging after 42 days of accelerated storage. K-ras mimotope expression was detected intracellularly and extracellularly in the freeze-dried L. lactis-fermented milk powder upon storage. CONCLUSIONS: This suggests that fermented milk powder is a suitable food carrier for this live oral vaccine.


Assuntos
Embalagem de Alimentos , Liofilização , Lactococcus lactis , Lactococcus lactis/metabolismo , Lactococcus lactis/genética , Embalagem de Alimentos/métodos , Animais , Vácuo , Pós , Produtos Fermentados do Leite/microbiologia , Fermentação , Leite/química , Genes ras/genética , Armazenamento de Alimentos
11.
Sci Rep ; 14(1): 17616, 2024 07 30.
Artigo em Inglês | MEDLINE | ID: mdl-39080472

RESUMO

Because of the lack of good seedling positioning during vegetable grafting, there are issues such as high labor costs and long grafting time. This article proposes a negative pressure suction seedling positioning method for seed leaves based on the characteristic parameters of cucumber spike wood, and designs a flexible adsorption positioning mechanism for spike wood. Firstly, the ventral surface curve trajectories of cucumber cotyledons were extracted using Matlab software, and then a shape-adaptive design was applied to the attachment surface of the flexible suction positioning mechanism, and a computational fluid dynamics model of the airflow field was established. By combining Fluent simulation analysis with orthogonal experiments, the effect of suction hole diameter, vacuum negative pressure value, suction hole quantity, and suction hole depth on the adsorption effect of the suction head was analyzed, the main and secondary factors and operational indicators that affect the adsorption effect are evaluated. The optimal parameter combination: suction hole diameter of 1.5 mm, vacuum negative pressure value of 2 kPa, suction hole quantity of 42, and suction hole depth of 2 mm, has been found. A verification experiment was conducted on a test bench, and the experimental results show that the success rate of leaf absorption using the optimal parameter combination is 97.69%, which indicates that the suction head is designed reasonably and meets the requirements of grafting.


Assuntos
Cucumis sativus , Folhas de Planta , Simulação por Computador , Adsorção , Verduras , Plântula , Vácuo
12.
J Environ Manage ; 366: 121725, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38971070

RESUMO

Co-digestion of kitchen waste (KW) and black water (BW) can be considered as an attractive method to efficiently achieve the clean energy from waste. To find the optimal operation parameters for the co-digestion, the effects of different temperatures (35 and 55 °C) and BW:KW ratios on the reactor performances, microbial communities and metabolic pathways were studied. The results showed that the optimum BW:KW ratio was 1:3.6 and 1:4.5 for mesophilic and thermophilic optimal reactors, with methane production of 449.04 mL/g VS and 411.90 mL/g VS, respectively. Microbial communities showed significant differences between the reactors under different temperatures. For bacteria, increasing BW:KW ratio significantly promoted Defluviitoga enrichment (1.1%-9.5%) under thermophilic condition. For Archaea, the increase in BW:KW ratio promoted the enrichment of Methanosaeta (8.6%-56.4%) in the mesophilic reactor and Methanothermobacter (62.0%-89.2%) in the thermophilic reactor. The analysis of the key enzymes showed that, acetoclastic methanogenic pathway performed as the dominant under mesophilic condition, with high abundance of Acetate-CoA ligase (EC:6.2.1.1) and Pyruvate synthase (EC:1.2.7.1). Hydrogenotrophic methanogenic pathway was the main pathway in the thermophilic reactors, with high abundance of Formylmethanofuran dehydrogenase (EC:1.2.99.5).


Assuntos
Reatores Biológicos , Anaerobiose , Metano/metabolismo , Redes e Vias Metabólicas , Bactérias/metabolismo , Vácuo , Archaea/metabolismo
13.
J Environ Manage ; 366: 121866, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-39018852

RESUMO

Today, synergistic combination of special nanomaterials (NMs) and electrospinning technique has emerged as a promising strategy to address both water scarcity and energy concerns through the development of photothermal membranes for wastewater purification and desalination. This work was organized to provide a new perspective on membrane design for photothermal vacuum membrane distillation (PVMD) through optimizing membrane performance by varying the localization of photothermal NMs. Poly(vinylidene fluoride) omniphobic photothermal membranes were prepared by localizing graphene oxide nanosheets (GO NSh) (1) on the surface (0.2 wt%), (2) within the nanofibers structure (10 wt%) or (3) in both positions. Considering the case 1, after 7 min exposure to the 1 sun intensity light, the highest temperature (∼93.5 °C) was recorded, which is assigned to the accessibility of GO NSh upon light exposure. The case 3 yielded to a small reduction in surface temperature (∼90.4 °C) compared to the case 1, indicating no need to localize NMs within the nanofibers structure when they are localized on the surface. The other extreme belonged to the case 2 with the lowest temperature of ∼71.3 °C, which is consistent with the less accessibility of GO NSh during irradiation. It was demonstrated that the accessibility of photothermal NMs plays more pronounced role in the membrane surface temperature compared to the light trapping. However, benefiting from higher surface temperature during PVMD due to enhanced accessibility of photothermal NMs is balanced out by decrease in the permeate flux (case 1: 1.51 kg/m2 h and case 2: 1.83 kg/m2 h) due to blocking some membrane surface pores by the binder. A trend similar to that for flux was also followed by the efficiency. Additionally, no change in rejection was observed for different GO NSh localizations.


Assuntos
Destilação , Membranas Artificiais , Nanoestruturas , Águas Residuárias , Purificação da Água , Nanoestruturas/química , Destilação/métodos , Águas Residuárias/química , Purificação da Água/métodos , Vácuo , Grafite/química
14.
Environ Geochem Health ; 46(8): 286, 2024 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-38967819

RESUMO

The vacuum preloading coupling flocculation treatment is a widely employed method for reinforcing soils with high water content in practical construction. However, uneven distribution and accumulation of flocculants pose significant damage to the soil environment and result in uneven soil consolidation, leading to severe issues in subsequent soil development and exploitation. To address these concerns, an evolved leaching with vacuum method is developed for facilitating soil consolidation while preventing the accumulation of flocculant in the soil. In this study, five model tests are conducted in which FeCl3 is chosen as the typical flocculant to promote soil consolidation, and deionized water is used for leaching. The final discharged water, settlement, water content and penetration resistance of soil are obtained to evaluate the soil reinforcement effect, while the flocculant removal effect is evaluated by the Fe3+ content in the filtrate and soil. The comprehensive reinforcement and flocculant removal effect show that this method is extremely effective compared to traditional vacuum preloading. The two leaching is clarified as the best choice, resulting in a 22% decrease in the soil water content and a 25% in soil penetration resistance, meanwhile a 12.8% removal rate of the flocculant. The test results demonstrate that leaching with vacuum preloading can contribute to promoting soil consolidation and reducing the accumulation of flocculant in the soil, ensuring the safe and eco-friendly use of the soil for future applications. The conclusions obtained are of significant theoretical value and technical support for practical construction and sustainable development.


Assuntos
Floculação , Solo , Solo/química , Vácuo , Poluentes do Solo/química , Compostos Férricos/química , Cloretos/química
15.
Meat Sci ; 216: 109590, 2024 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-38991480

RESUMO

The packaging system is one of the factors influencing the preservation of the nutritional value, microbiological safety, and sensory attributes of meat. The study investigated changes in physicochemical and microbiological properties taking place during 15-day refrigerated storage of two calf muscles, the longissimus lumborum (LL) and semitendinosus (ST), packaged in three systems, respectively, vacuum packing (VP), modified atmosphere packaging (MAP, 80% O2 + 20% CO2), and a combined system (VP + MAP, 8 d in VP followed by 7 d in MAP). LL and ST stored in VP had significantly lower levels of lipid oxidation, higher α-tocopherol content, and higher instrumentally measured tenderness in comparison with the samples stored in MAP. On the other hand, the MAP samples had lower purge loss at 5 and 15 days, a higher proportion of oxymyoglobin up to 10 days of storage, and a better microbiological status. Calf muscle samples stored in the VP + MAP system had intermediate values for TBARS and α-tocopherol content and at the same time were the most tender and had the lowest counts of Pseudomonas and Enterobacteriaceae bacteria at 15 days. All packaging systems ensured relatively good quality of veal characteristics up to the last day of storage. However, for MAP at 15 days of storage, unfavourable changes in colour (a high level of metmyoglobin and a decrease in oxymyoglobin, redness and R630/580 ratio) and in the lipid fraction (a high TBARS value and a significant decrease in α-tocopherol content) were observed.


Assuntos
Embalagem de Alimentos , Armazenamento de Alimentos , Músculo Esquelético , Carne Vermelha , Substâncias Reativas com Ácido Tiobarbitúrico , alfa-Tocoferol , Embalagem de Alimentos/métodos , Animais , Bovinos , alfa-Tocoferol/análise , Vácuo , Músculo Esquelético/química , Substâncias Reativas com Ácido Tiobarbitúrico/análise , Carne Vermelha/análise , Carne Vermelha/microbiologia , Cor , Microbiologia de Alimentos , Mioglobina/análise , Peroxidação de Lipídeos , Enterobacteriaceae/isolamento & purificação , Pseudomonas
16.
Chemosphere ; 363: 142846, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39025306

RESUMO

Peroxy radicals (RO2) are key reactive intermediates in atmospheric oxidation processes and yet their chemistry is not fully unraveled. Little is known about their structures and the structures of the dimeric products (ROOR) in the self-reaction of small RO2, which are among the most abundant RO2 in the atmosphere. The product branching ratios of ROOR and their atmospheric roles are still in controversy. Here, the self-reaction of propyl peroxy radicals (C3H7O2), a typical small RO2 radical in the atmosphere, has been studied using synchrotron radiation vacuum ultraviolet photoionization mass spectrometry. Both radical (C3H7O) and closed-shell molecular (C3H6O, C3H7OH, C3H7OOC3H7) products in the self-reaction are observed in photoionization mass spectra and their elusive isomers are definitely identified in mass-selected photoionization spectra. Three isomers of the C3H7OOC3H7 dimeric products, R1OOR1, R1OOR2, and R2OOR2 (R1 and R2 represent 1-C3H7 and 2-C3H7, respectively), as well as their complex structures have been determined for the first time. Kinetic experiments are performed and compared with chemical simulations to reveal the sources of specific products. The branching ratio of the C3H7OOC3H7 dimeric channel is measured at 10 ± 5%. This work demonstrates that the dimeric product formation in the self-reaction of small RO2 radicals is non-negligible and should provide valuable new insight into atmospheric modelling.


Assuntos
Espectrometria de Massas , Síncrotrons , Atmosfera/química , Raios Ultravioleta , Vácuo , Oxirredução , Cinética , Peróxidos/química , Peróxidos/análise , Processos Fotoquímicos
17.
Dental Press J Orthod ; 29(3): e2423117, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38985074

RESUMO

OBJECTIVE: This study aimed to clinically compare the accuracy of bracket positioning between three-dimensionally (3D) printed indirect bonding trays and vacuum-formed trays made over 3D-printed models. MATERIAL AND METHODS: Fourteen patients, planned for fixed orthodontic therapy, were randomly divided into two equal groups. For both groups, both dental arches were scanned, to acquire virtual models, brackets were virtually positioned from central incisors to second premolars, and scans for the final bracket positions were performed. In the first group, transfer trays were 3D-printed. In the second group, virtual models were 3D-printed, and vacuum-formed soft sheets were thermoformed on the printed model. Teeth were indirectly bonded and then scanned. Superimposition of the virtual and the final bracket positioning scans was performed to measure linear and angular deviations in brackets positions. RESULTS: The first group showed significantly less occlusogingival and buccolingual linear errors than the second group. No significant differences in angular deviations were found between both groups. The frequencies of clinically acceptable linear errors within 0.5 mm and angular errors within 2° showed no statistically significant difference between both groups (p> 0.05 for all measurements). The transfer errors in both groups showed linear directional biases toward the mesial, gingival and labial directions. There was no statistically significant difference in the rate of immediate debonding between both groups (10.7% and 7.1% for the first and the second groups, respectively, p=0.295). CONCLUSIONS: 3D-printed indirect bonding trays were more accurate than vacuum-formed trays, in terms of linear deviations. Both types of trays showed similar angular control.


Assuntos
Colagem Dentária , Braquetes Ortodônticos , Impressão Tridimensional , Humanos , Colagem Dentária/métodos , Modelos Dentários , Feminino , Vácuo , Masculino , Adolescente , Adulto Jovem , Dente Pré-Molar/diagnóstico por imagem
18.
J Chromatogr A ; 1730: 465104, 2024 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-38905947

RESUMO

For the first time, a method for the simultaneous analysis of fifteen polycyclic aromatic hydrocarbons (PAHs), including light and heavy PAHs, in açaí-based food products (AFPs) was developed using vacuum-assisted sorbent extraction (VASE) combined with gas chromatography-mass spectrometry (GC-MS). The method requires no organic solvents and is amenable to full automation. To achieve optimal analytical extraction conditions, VASE parameters including stirring rate, extraction time, desorption temperature, desorption time, preheat time, and preheat temperature were optimized using sequential multivariate optimization. The method was validated and yielded limits of quantification below 1 µg kg-1 for all analytes, with recoveries ranging from 65 % to 112 % and good precision (≤11 % relative standard deviation). Additionally, the greenness and practical aspects of the method were investigated using the Green Analytical Procedure Index (GAPI), eco-scale, and the Blue Applicability Grade Index (BAGI), respectively. The VASE-GC-MS approach is suitable for routine analysis and exhibits characteristics of a green analytical method. No PAHs were detected above the limits of detection in thirty samples of AFPs.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas , Limite de Detecção , Hidrocarbonetos Policíclicos Aromáticos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Hidrocarbonetos Policíclicos Aromáticos/análise , Hidrocarbonetos Policíclicos Aromáticos/isolamento & purificação , Vácuo , Extração em Fase Sólida/métodos , Contaminação de Alimentos/análise , Química Verde/métodos , Análise de Alimentos/métodos , Reprodutibilidade dos Testes
19.
Forensic Sci Int ; 361: 112079, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38850613

RESUMO

DNA retrieval methods traditionally used during forensic evidence recovery including swabbing and tape lifting, can have limited effectiveness when used on porous, rough substrates such as bricks and carpet. This is possibly due to the DNA material being dispersed and unreachable for surface sampling techniques. In this evaluation we investigated the effectiveness of the Microbial Wet-Vacuum System (M-Vac®; M-Vac® Systems, Inc., Sandy, UT), as it has been reported to retrieve greater amounts of DNA material from challenging exhibits. A four-stage evaluation was conducted, starting with seeding carpet and brick substrates with a known donor's saliva in two dilutions and comparing the DNA recovery of tape lifting, swabbing, and the M-Vac®. A victim struggle scenario on carpet was then mimicked to compare trace DNA recovery by each method. Two mock scenarios were also conducted; a shirt was submerged in a creek bed for a period of five days to sample for the wearer's DNA, and a car boot was sampled to assess the possibility of recovering a victim's DNA amongst background DNA from the usual car occupants. Finally, the compatibility of the M-Vac® sampling process was optimised for the fully automated DNA lysis and extraction platforms used in the NSW (Australia) jurisdiction by comparing filter subsampling methods. The results from the study were mixed. For bricks, none of the collection methods were effective in retrieving DNA. On carpet, the M-Vac® retrieved the greatest quantities of DNA from the saliva-seeded samples, however, tape lifts outperformed all methods for 'touch' DNA recovery. The M-Vac® retrieved the greatest amount of DNA from the t-shirt recovered from a creek bed as it was able to retrieve the embedded DNA. The final mock case car boot scenario resulted in greater victim DNA recovery from tape lifts, with the M-Vac® more likely to recover mixtures too weak and/or complex to be interpreted. Finally, operational considerations regarding the compatibility of the M-Vac® system with fully automated DNA lysis and extraction are discussed. Considering the substantial time and cost to deploy the M-Vac®, it is recommended to be utilised in casework only after swabbing and tape lifting methods have failed to yield sufficient DNA material, where the substrate properties would likely benefit from the M-Vac's® niche capabilities for retrieving embedded DNA, and low levels of background DNA may be anticipated.


Assuntos
Impressões Digitais de DNA , DNA , Saliva , Manejo de Espécimes , Humanos , Manejo de Espécimes/instrumentação , Manejo de Espécimes/métodos , DNA/isolamento & purificação , DNA/análise , Saliva/microbiologia , Saliva/química , Vácuo , Porosidade , Reação em Cadeia da Polimerase , Pisos e Cobertura de Pisos , Materiais de Construção/microbiologia
20.
Anal Chem ; 96(26): 10524-10533, 2024 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-38907695

RESUMO

The elucidation of protein-membrane interactions is pivotal for comprehending the mechanisms underlying diverse biological phenomena and membrane-related diseases. In this investigation, vacuum-ultraviolet circular dichroism (VUVCD) spectroscopy, utilizing synchrotron radiation (SR), was employed to dynamically observe membrane interaction processes involving water-soluble proteins at the secondary-structure level. The study utilized a time-resolved (TR) T-shaped microfluidic cell, facilitating the rapid and efficient mixing of protein and membrane solutions. This system was instrumental in acquiring measurements of the time-resolved circular dichroism (TRCD) spectra of ß-lactoglobulin (bLG) during its interaction with lysoDMPG micelles. The results indicate that bLG undergoes a ß-α conformation change, leading to the formation of the membrane-interacting state (M-state), with structural alterations occurring in more than two steps. Global fitting analysis, employing biexponential functions with all of the TRCD spectral data sets, yielded two distinct rate constants (0.18 ± 0.01 and 0.06 ± 0.003/s) and revealed a unique spectrum corresponding to an intermediate state (I-state). Secondary-structure analysis of bLG in its native (N-, I-, and M-states) highlighted that structural changes from the N- to I-states predominantly occurred in the N- and C-terminal regions, which were prominently exposed to the membrane. Meanwhile, transitions from the I- to M-states extended into the inner barrel regions of bLG. Further examination of the physical properties of α-helical segments, such as effective charge and hydrophobicity, revealed that the N- to I- and I- to M-state transitions, which are ascribed to first- and second-rate constants, respectively, are primarily driven by electrostatic and hydrophobic interactions, respectively. These findings underscore the capability of the TR-VUVCD system as a robust tool for characterizing protein-membrane interactions at the molecular level.


Assuntos
Dicroísmo Circular , Lactoglobulinas , Lactoglobulinas/química , Lactoglobulinas/metabolismo , Vácuo , Micelas , Estrutura Secundária de Proteína , Animais , Fatores de Tempo , Bovinos
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