Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 123
Filtrar
Mais filtros

Intervalo de ano de publicação
1.
J Chromatogr A ; 1713: 464525, 2024 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-38000198

RESUMO

Lubricating oils help an internal combustion engine function effectively by reducing friction and wear on the engine's moving parts. They typically consist of petroleum-derived base oil and various additives to achieve the desired characteristics in automotive engine oils. Determination of aromatics and polar additives in the finished and used lubricating oils is not possible with existing methods hence their development is significant from the perspectives of environment and reuse/re-refining of used lubricating oils. This study reports the development of a new HPLC method to determine additives in the finished lubricating oils and/or polars in the used engine oils. The proposed method is simple, fast (runtime of 13 min), does not require sample pre-treatment, and exhibits high precision and superior limits of detection and quantification. The method demonstrated good linear response ranging from 0.1 to 30 mass for total aromatics and 0.1 to 20 % for additives. The method validation was carried out by analyzing brand-new commercial two and four-wheeler lubricants with used automotive lubricants. Based on the proposed method, the aromatics and additives concentration ranges in the studied finished lubricants were estimated between 0.20-1.70 % (mass) and 0.20-3.50 % (mass), respectively. Similarly, for used lubricants, the aromatics and additives were estimated to be 1.00-6.10 % and 0.60-2.40 % (mass), respectively.


Assuntos
Hidrocarbonetos Aromáticos , Petróleo , Cromatografia Líquida de Alta Pressão , Óleos , Petróleo/análise , Lubrificantes/análise , Lubrificantes/química
2.
Chemosphere ; 309(Pt 1): 136622, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36181837

RESUMO

Lubricants operate as antifriction media, preserving machine reliability, facilitating smooth operation, and reducing the likelihood of frequent breakdowns. The petroleum-based reserves are decreasing globally, leading to price increases and raising concerns about environmental degradation. The researchers are concentrating their efforts on developing and commercializing an environmentally friendly lubricant produced from renewable resources. Biolubricants derived from nonedible vegetable oils are environmentally favorable because of their non-toxicity, biodegradability, and close to net zero greenhouse gas emissions. The demand for bio lubricants in industry and other sectors is increasing due to their non-toxic, renewable, and environmentally friendly nature. Good lubrication, anti-corrosion, and high flammability are characteristic properties of vegetable oils due to their unique structure. This study presents several key properties of nonedible oils that are used to produce lubricants via the transesterification process. Bibliometric analysis is also performed, which provides us with a better understanding of previous studies related to the production of bio lubricants from the transesterification process. Only 371 published documents in the Scopus database were found to relate to the production of bio lubricants using the transesterification process. The published work was mostly dominated by research articles (286; 77.088%). Significant development can be seen in recent years, with the highest occurrence in 2021, reaching 68 publications accounting for 18.38% of the total documents. In the second step, (i) the authors with the most number of publications; (ii) journals with the most productions; (iii) most productive countries; and (iv) the authors' most frequently used keywords were evaluated. These results will provide a pathway for researchers interested in this field. Lastly, recommendation is made on research gaps to device possible strategies for its commercialization.


Assuntos
Gases de Efeito Estufa , Petróleo , Reprodutibilidade dos Testes , Lubrificantes/química , Óleos de Plantas
3.
Environ Pollut ; 311: 119885, 2022 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-35977637

RESUMO

Hydrocarbons pose significant risks to marine ecosystems. A field experiment investigated the effects of four different hydrocarbon products (diesel fuel and three lubricating oils: Unused, Used and Biodegradable) on sediment macrofaunal communities over a five year period, in a shallow Antarctic marine embayment. Sediments were defaunated, treated with a hydrocarbon and deployed in trays (including a control) on the seabed. Diesel fuel had the biggest initial impact on communities, with strong effects at 5 weeks and 1 year, in particular on annelids, but also on amphipods, ostracods and cumaceans. By five years, however, the effect of diesel was less than that of lubrication oils and showed more recovery than oiled treatments and the biggest effect was from the Used oil. There was an effect of hydrocarbons on diversity, especially diesel, at 5 weeks and 1 year, but by 2 and 5 years diversity was not different or greater in hydrocarbon treatments than controls. Total abundance was always lower in hydrocarbon treatments than controls, especially for crustaceans, but annelids were more abundant in oil treatments than controls at 5 years. Oils, and in some cases diesel, enhanced the abundance of some taxa at 2-5 years, including molluscs, some polychaete families (capitellids, cirratulids, dorvilleids), oligochaetes, as well as ostracods, cumaceans and isopods. Amphipods and tanaids were most sensitive to hydrocarbons, and annelids were very sensitive to diesel. The Biodegradable oil had similar magnitude community effects to standard oil at 5 years, but annelids were more affected by Biodegradable oil, particularly at 1 and 2 years, and it did not enhance annelid or mollusc abundance at 5 years like the other oils, except for some polychaete families. Impacts of spilled hydrocarbons in Antarctica will persist well beyond 5 years, but diesel impacts will recover faster than oil.


Assuntos
Anfípodes , Poluição por Petróleo , Petróleo , Animais , Regiões Antárticas , Ecossistema , Gasolina , Sedimentos Geológicos , Humanos , Hidrocarbonetos , Lubrificantes , Óleos , Poluição por Petróleo/análise
4.
ACS Appl Mater Interfaces ; 14(28): 31667-31676, 2022 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-35791814

RESUMO

At present, microscale high-throughput screening (HTS) for drug toxicity has drawn increased attention. Reported methods are often constrained by the inability to execute rapid fusion over diverse droplets or the inflexibility of relying on rigid customized templates. Herein, a light-responsive candle-soot-hybridized lubricant-infused slippery surface (CS-LISS) was reported by one-step femtosecond laser cross-scanning to realize highly effective and flexible drug HTS. Due to its low-hysteresis merits, the CS-LISS can readily steer diverse droplets toward arbitrary directions at a velocity over 1.0 mm/s with the help of tracing lateral near-infrared irradiation; additionally, it has the capability of self-cleaning and self-deicing. Significantly, by integrating the CS-LISS with a GFP HeLa cell chip, high-efficiency drug toxicity screening can be successfully achieved with the aid of fluorescence imaging. This work provides insights into the design of microscale high-throughput drug screening.


Assuntos
Pró-Fármacos , Testes de Toxicidade , Avaliação Pré-Clínica de Medicamentos , Excipientes/química , Células HeLa , Humanos , Lubrificantes/química , Imagem Óptica , Pró-Fármacos/química , Pró-Fármacos/toxicidade , Fuligem
5.
Sci Rep ; 12(1): 11941, 2022 07 13.
Artigo em Inglês | MEDLINE | ID: mdl-35831357

RESUMO

Vegetable oils, whose hydrocarbon structure is very similar to that of petroleum products, are ideal renewable and sustainable alternatives to petroleum lubricants. Bio-lubricants are commonly synthesized by modifying the chemical structure of vegetable oils. In this study, microwave irradiation was applied to intensify the mass-transfer-limited transesterification reaction to produce trimethylolpropane triester (bio-lubricant) from camelina oil as a promising local energy crop. A rotatable RSM-BBD method was applied to find the optimal levels of experimental factors, namely reaction time (67.8 min), the catalyst concentration (1.4 wt%) and the molar ratio (3.5). In these optimal levels, the reaction yield of 94.3% was obtained with desirability of 0.975. The quadratic statistical model with a determination coefficient of 97.97%, a standard deviation of 0.91 and a variation coefficient of 1% was suggested as the most appropriate model by Design-Expert software. Finally, the physicochemical properties of the purified product were in accordance with the requirements of the ISO-VG22 base oil standard.


Assuntos
Lubrificantes , Petróleo , Biocombustíveis , Catálise , Lubrificantes/química , Micro-Ondas , Óleos de Plantas , Propilenoglicóis
6.
Environ Pollut ; 307: 119569, 2022 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-35680061

RESUMO

A biological treatment method was tested in laboratory conditions for the removal of hydrocarbons contained in a waste disposal soil sample consisting of excavated sandy soil from a former fueling station. Two fractions of hydrocarbons were quantified by GC-FID: diesel (C10-C21) and lubricant oil (C22-C40). Meat and bone meal (MBM, 1% w/w) was used as a bio-stimulant agent for soil organisms. Cyclodextrin, an oligosaccharide produced from starch by enzymatic conversion, was also used to assess its ability to improve the bioavailability/biodegradability of hydrocarbons in the soil. Parameters such as temperature, pH, water content and aeration (O2 availability) were monitored and optimized to favor degradation processes. Two different experimental tests were prepared: one to measure the degradation of hydrocarbons; the other to monitor the mobility of some elements in the soil and in the leachate produced by watering with tap water. Soil samples treated with MBM and cyclodextrin showed, over time, a greater removal of the more persistent hydrocarbon fraction (lubricant oil). MBM-treated soils underwent a faster hydrocarbon removal kinetic, especially in the first treatment period. However, the final hydrocarbon concentrations are comparable in all treatments, including control. Over time, the effect of cyclodextrin on hydrocarbon degradation seemed to be relevant. MBM-treated soils sequestered lead in the very first weeks. These results highlight the intrinsic capacity of soil, and its indigenous microbial communities, to degrade petroleum hydrocarbons and suggest that MBM-induced bioremediation is a promising, environmentally friendly technology which should be considered when dealing with hydrocarbon/heavy metal co-contaminated soils.


Assuntos
Ciclodextrinas , Metais Pesados , Petróleo , Poluentes do Solo , Biodegradação Ambiental , Hidrocarbonetos/metabolismo , Lubrificantes , Petróleo/metabolismo , Solo/química , Microbiologia do Solo , Poluentes do Solo/análise , Água
7.
J Oleo Sci ; 71(6): 915-925, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35661069

RESUMO

In this study, bio-based ionic liquid prepared from ricinoleic acid and choline was firstly used as additive in lithium base grease. The characterization and tribological performance of the prepared ionic liquid ([cho][ricinoleic]) as additive in grease were studied compared with the traditional ionic liquid such as L-P104. All the concentrations showed promising friction-reducing and anti-wear properties, though a 3% concentration has superior lubricating properties than others. Furthermore, [cho][ricinoleic]) can greatly enhance the lubrication capability of lithium base greaseunder different frequency and load at room temperature. Although L-P104 showed good lubricating performance than [cho][ricinoleic] at 150°C, the chosen formulation (1.5% [cho][ricinoleic] + 1.5% L-P104) could have better synergism at high and room temperature, which could be a good supplement to ionic liquid as grease additive. Thin films formed according to the results of SEM and XPS were attributed to be the main account for the preferable tribological properties of [cho][ricinoleic] in lithium base grease.


Assuntos
Líquidos Iônicos , Lítio , Colina , Hidrocarbonetos , Lubrificantes , Ácidos Ricinoleicos
8.
Int Ophthalmol ; 42(10): 3221-3228, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35546379

RESUMO

PURPOSE: To determine the prevalence of adenoviral conjunctivitis in Turkish ophthalmologists, to provide an overview of the treatment and prophylaxis of adenoviral conjunctivitis, and to analyze the data in the context of evidence-based treatment recommendations. METHODS: An online questionnaire consisting of 20 multiple-choice questions about the characteristics of the respondents, the individual adenoviral conjunctivitis history of the ophthalmologists, their practice's approaches, and prescription preferences were emailed to Turkish ophthalmologists. RESULTS: The survey was emailed to 500 ophthalmologists; 45% of them returned the questionnaire. According to the responses, the history of adenoviral conjunctivitis infections was positive in 46.7% (n: 120), recurrent attack prevalence was 16.2% in ophthalmologists. Lubricants (67.6%) are the most preferred first-line treatment options for adenoviral conjunctivitis, followed by povidone-iodine (59.6%), topical antibiotics (51.1%), topical antivirals (29.3%), topical corticosteroids (26.7%), and topical nonsteroidal anti-inflammatory agents (19.6%). A total of 98.2% preferred to dismiss infected patients. The preferred prophylaxis options were frequent hand washing/use of gloves (97.8%), disinfection of medical devices (95.1%), isolation of infected patients (79.1%), hand hygiene with gemicides (58.7%). The percentage of single-dose eye drop selection was 46.2. CONCLUSIONS: The findings of this survey showed that most Turkish ophthalmologists generally follow international guidelines for the treatment of adenoviral conjunctivitis. The treatment algorithm is still controversial, so ophthalmologists should be aware of treatment guideline updates in line with evidence-based recommendations. Having sufficient knowledge of the basic characteristics of viruses is important to control the spread of the disease.


Assuntos
Infecções por Adenoviridae , Conjuntivite Viral , Conjuntivite , Oftalmologistas , Infecções por Adenoviridae/tratamento farmacológico , Corticosteroides/uso terapêutico , Antibacterianos/uso terapêutico , Anti-Inflamatórios não Esteroides/uso terapêutico , Antivirais/uso terapêutico , Conjuntivite/tratamento farmacológico , Conjuntivite Viral/tratamento farmacológico , Conjuntivite Viral/epidemiologia , Conjuntivite Viral/prevenção & controle , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Lubrificantes/uso terapêutico , Soluções Oftálmicas/uso terapêutico , Povidona-Iodo/uso terapêutico , Inquéritos e Questionários
9.
Molecules ; 27(9)2022 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-35566043

RESUMO

In this study, soybean oil deodorizer distillate (SODD), a mixture of free fatty acids and acylglycerides, and isoamyl alcohol were evaluated as substrates in the synthesis of fatty acid isoamyl monoesters catalyzed by Eversa (a liquid formulation of Thermomyces lanuginosus lipase). SODD and the products were characterized by the chemical and physical properties of lubricant base stocks. The optimal conditions to produce isoamyl fatty acid esters were determined by response surface methodology (RSM) using rotational central composite design (RCCD, 23 factorial + 6 axial points + 5 replications at the central point); they were 1 mol of fatty acids (based on the SODD saponifiable index) to 2.5 mol isoamyl alcohol, 45 °C, and 6 wt.% enzymes (enzyme mass/SODD mass). The effect of the water content of the reactional medium was also studied, with two conditions of molecular sieve ratio (molecular sieve mass/SODD mass) selected as 39 wt.% (almost anhydrous reaction medium) and 9 wt.%. Ester yields of around 50 wt.% and 70 wt.% were reached after 50 h reaction, respectively. The reaction products containing 43.7 wt.% and 55.2 wt.% FAIE exhibited viscosity indices of 175 and 163.8, pour points of -6 °C and -9 °C, flash points of 178 and 104 °C, and low oxidative stability, respectively. Their properties (mainly very high viscosity indices) make them suitable to be used as base stocks in lubricant formulation industries.


Assuntos
Lubrificantes , Óleo de Soja , Esterificação , Ácidos Graxos/química , Lipase/química , Óleo de Soja/química
10.
ACS Appl Mater Interfaces ; 14(15): 17940-17949, 2022 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-35394750

RESUMO

We report the design of slippery liquid-infused porous surfaces (SLIPS) fabricated from building blocks that are biodegradable, edible, or generally regarded to be biocompatible. Our approach involves infusion of lubricating oils, including food oils, into nanofiber-based mats fabricated by electrospinning or blow spinning of poly(ε-caprolactone), a hydrophobic biodegradable polymer used widely in medical implants and drug delivery devices. This approach leads to durable and biodegradable SLIPS that prevent fouling by liquids and other materials, including microbial pathogens, on objects of arbitrary shape, size, and topography. This degradable polymer approach also provides practical means to design "controlled-release" SLIPS that release molecular cargo at rates that can be manipulated by the properties of the infused oils (e.g., viscosity or chemical structure). Together, our results provide new designs and introduce useful properties and behaviors to antifouling SLIPS, address important issues related to biocompatibility and environmental persistence, and thus advance new potential applications, including the use of slippery materials for food packaging, industrial and marine coatings, and biomedical implants.


Assuntos
Incrustação Biológica , Polímeros , Incrustação Biológica/prevenção & controle , Excipientes , Lubrificantes , Óleos de Plantas , Polímeros/química , Porosidade
11.
Environ Res ; 212(Pt B): 113325, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35439455

RESUMO

Oil spills have many adverse effects on the marine environment. Bilge oil spills occur frequently in the sea as a result of maritime accidents or illegal discharge. It is difficult to unambiguously identify the specific sources of such spills because bilge oil contains a mixture of fuel oil and lubricant. In this study, bilge oils with different fuel oil/lubricant ratios were prepared and analyzed using a modified version of the CEN/TR methodology (European Committee for Standardization, 2012). As the lubricant content of bilge oil increased, the intensity of the C20-C24 group, which is the commonly-used normalization compound group for fuel oil in the percentage weathering (PW) plot, also changed. Therefore, the mean area of the C15-C18 group, which was affected by the lubricant content, was used instead. Although heavy fuel oil is usually normalized to a hopane, bilge oil with a high lubricant content cannot be analyzed based on a mass spectrometry (MS)-PW plot; thus, heavy fuel oil-based bilge oil was normalized to a phytane in this study. Although hopanes and styrenes are unsuitable comparison compounds for heavy fuel oil-based bilge oil analysis, for light fuel oil-based bilge oil, hopanes and steranes could be applied as diagnostic ratio comparisons when the lubricant peak was clearly detected in the chromatograms of the spilled and suspected oil samples. By applying the CEN/TR methodology according to this approach, the similarities between spilled and suspected oil samples were more easily revealed. In addition, the field applicability of the proposed method was tested for four actual oil spills.


Assuntos
Óleos Combustíveis , Poluição por Petróleo , Petróleo , Óleos Combustíveis/análise , Lubrificantes , Óleos , Triterpenos Pentacíclicos , Petróleo/análise , Poluição por Petróleo/análise
12.
Environ Sci Pollut Res Int ; 29(37): 56215-56248, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35334052

RESUMO

Vegetable oil-based bio-lubricants possess potential as an alternative to mineral oil-based lubricants due to their biodegradability and renewability. However, a detailed examination of the publication focus, trend, and future direction related to these bio-lubricants' tribological and physicochemical properties is scarce. Therefore, the study presents a bibliometric analysis of vegetable oil-based bio-lubricant. One hundred sixty-five publications were extracted from Web of Science (WoS) from 2010 to 2021. During this period, the total citation was 2,240, recording an average citation per publication of 13.58. Proceedings of The Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology was the top productive journal, publishing 10.3% of the publications selected on the studied topic. From 2010 to 2021, India was the most productive country working on bio-lubricants due to its abundance of coconut products, followed by Malaysia due to its abundance of palm products. The keyword analysis indicated that a significant amount of work emphasised the derivation of bio-lubricants with an increasing shift towards tribological performance characterisation. From the analysis, palm is the most studied bio-lubricant, followed by castor oil. The reported viscosity and viscosity index values cover an extensive range, allowing these bio-lubricants to be adopted for a wide range of applications. For different vegetable oil-based bio-lubricants, the coefficient of friction is reported from 0.001 to 0.78, with the wear scar diameter being reported from 0.075 µm to 4.59 mm. Even though these bio-lubricants' friction and wear performances can be tabulated, the dataset is still unreliable for lubricant-selection purposes because of the varying test conditions. Such a scenario also limits the ability to correlate the role of fatty acid composition in the vegetable oil-based bio-lubricants in fulfilling their various application-specific potentials. Therefore, this study recommends that a unified correlation between the fatty acid composition and its tribological performance be attained consistently to better elucidate the potential of vegetable oil-based bio-lubricants.


Assuntos
Lubrificantes , Óleos de Plantas , Bibliometria , Ácidos Graxos , Fricção , Lubrificantes/química , Óleos de Plantas/química
13.
Artigo em Inglês | MEDLINE | ID: mdl-35134664

RESUMO

Lubricating oils are composed of base oils (>85% v/v) and enriching additives (<15% v/v). Three types of base oils may be distinguished: 1) traditional bases (obtained by low-volatile fractions from crude oil distillation refining), 2) synthetic bases (mainly poly-alpha-olefins, sometimes esters, especially succinic acid esters), 3) bases of natural origin (especially obtained from refined plant oils). The bases of natural origin are the only ones recommended for application when lubricating oil may be emitted to the environment (e.g. when the machine with an open cutting system is used). Group-type separation and analysis of group-type composition of base and lubricating oils are of significant importance in quality control and environmental monitoring. Due to the potentially wide range of polarity of the components of base and lubricating oils, group- type separation becomes a difficult separation problem. It is also a serious analytical problem due to the considerable diversity of physicochemical properties. The authors propose a new procedure for the separation and determination of the group-type composition of base and lubricating oils using thin-layer liquid chromatography in normal phase systems (abr. NP-TLC) on silica gel plates impregnated with berberine salt/in the coupling of thin-layer chromatography with flame ionization detection (abr. TLC-FID). A new, effective procedure of TLC plates impregnation with berberine sulphate was presented. The proposed procedure ensures the visualization of all groups of base oils. Extensive experimental research showed that a 2-step development procedure with application of n-hexane up to 100% height of development +15 min and further n-hexane: isopropanol: tri-fluoroacetic acid 96.25: 3: 0.75 (v: v: v) up to 75% height of development is advantageous for the group-type separation, both in TLC-FID and TLC.


Assuntos
Cromatografia em Camada Fina/métodos , Lubrificantes , Óleos , Petróleo/análise , Berberina/química , Ionização de Chama , Lubrificantes/análise , Lubrificantes/química , Lubrificantes/isolamento & purificação , Óleos/análise , Óleos/química , Óleos/isolamento & purificação
14.
J Cancer Surviv ; 16(6): 1296-1338, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-34664199

RESUMO

PURPOSE: Side-effects of adjuvant endocrine therapy (AET) are common in breast cancer survivors, and can affect adherence to treatment. We synthesised the evidence for strategies to self-manage these side-effects. METHODS: We searched for systematic reviews and clinical guidelines on self-management strategies for AET side-effects (arthralgia, fatigue, hot flashes, gastrointestinal discomfort, nausea, vulvovaginal symptoms, and sleep disturbance). We searched oncology organisation's websites and eight databases (Inception-November 2020). Screening, data extraction and quality assessment were completed independently in duplicate. PROSPERO: 2019CRD4201914001. RESULTS: We identified 33 systematic reviews and 18 clinical guidelines. 21% of reviews were high quality, and the average quality score for guidelines was 44%. Evidence for most strategies was absent or weak. There was consensus from a low-quality review and multiple guidelines to recommend moisturisers, gels and lubricants for vulvovaginal symptoms. Evidence was weak for physical activity for self-managing most symptoms, although two high-quality reviews indicated yoga and aerobic exercise could reduce fatigue. Primary research was often biased by weak and underpowered study designs. Eleven reviews did not report information on adverse events. CONCLUSIONS: Most self-management strategies for breast cancer survivors experiencing side-effects from AET lack evidence. Primary research is needed using high-quality well-powered designs focusing on implementable strategies. IMPLICATIONS FOR CANCER SURVIVORS: Patients and clinicians should be aware that although the risk of harm is low for these self-management strategies, the likelihood of benefit is often unclear. Women should consider moisturisers, gels or lubricants for self-managing vulvovaginal symptoms, and yoga or aerobic exercise for alleviating fatigue.


Assuntos
Neoplasias da Mama , Sobreviventes de Câncer , Autogestão , Humanos , Feminino , Neoplasias da Mama/tratamento farmacológico , beta-Aminoetil Isotioureia/uso terapêutico , Revisões Sistemáticas como Assunto , Fadiga/induzido quimicamente , Fadiga/terapia , Lubrificantes/uso terapêutico
15.
Sensors (Basel) ; 21(24)2021 Dec 08.
Artigo em Inglês | MEDLINE | ID: mdl-34960293

RESUMO

This work reports the results of a study on the behaviour of five sensors recently developed for oil conditions monitoring, installed in-line in an experimental test rig for lubricants. The tests were carried out on seven oils of different origins (one synthetic ester, two bio-based synthetic esters, four vegetable oils) and use (two UTTOs and five hydraulic oils), under controlled working conditions, according to a specially designed test method. At first, the study concerned the identification of the conditions for the correct sensors' installation. Then, the tests started applying to the fluids severe work cycles intended to accelerate oil ageing. The data of viscosity, permittivity, relative humidity, electric conductivity, particle contamination, and ferro-magnetic particles provided by the sensors were compared to the results of laboratory analyses made on oil samples taken during the tests with the aim of verifying the sensors measurements accuracy and reliability and selecting the more suitable ones to in-line oil conditions monitoring, in the perspective of introducing them also in field applications, e.g., on agricultural tractors, for preventing damages due to oil deterioration, and in managing the machine maintenance.


Assuntos
Lubrificantes , Óleos de Plantas , Ésteres , Reprodutibilidade dos Testes , Viscosidade
16.
Med Eng Phys ; 98: 83-90, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34848043

RESUMO

Tribological study of zirconia toughened alumina against alumina is investigated using ball-on-disk tribometer with different bio-lubricants. Friction and wear coefficients are estimated for these bio-lubricants under four different loading conditions which are equivalent to regular and risky human gait activities. Experiments are carried out for a total sliding distance of 10 km with each bio-lubricant to estimate its friction and wear coefficients. Using submodeling finite element approach, cumulative linear and volumetric wear is estimated with the help of contact pressure. The sesame oil bio-lubricant showed better wear coefficient for risky gait activities and Ringer's solution exhibited minimum wear coefficient for normal walking gait activity. Overall minimum cumulative linear and volumetric wear for 2 million cycles was obtained for Ringer's solution.


Assuntos
Óxido de Alumínio , Prótese de Quadril , Análise de Elementos Finitos , Humanos , Lubrificantes , Teste de Materiais , Zircônio
17.
San Salvador; MINSAL; dic. 21, 2021. 30 p. graf, tab.
Não convencional em Espanhol | BISSAL, LILACS | ID: biblio-1353605

RESUMO

Los presentes lineamientos técnicos han sido elaborados en función de garantizar la cobertura y el acceso universal en salud. Sin embargo, la prevención de ITS/VIH, en particular en los grupos de población clave y vulnerable, se ve impactada por el estigma y discriminación, desigualdad en materia de género, violencia, falta de poder de decisión de las comunidades y vulneraciones de los derechos humanos, derechos sexuales y derechos reproductivos. Es debido a lo anterior, que se han identificado acciones necesarias plasmadas en este documento, para superar dichas barreras de acceso en estos grupos de población


These technical guidelines have been prepared in order to guarantee the coverage and universal access in health. However, STI/HIV prevention, particularly in groups of key and vulnerable population, is impacted by stigma and discrimination, inequality in of gender, violence, lack of decision-making power of the communities and violations of the rights human rights, sexual rights and reproductive rights. It is due to the above, that they have been identified necessary actions embodied in this document, to overcome these barriers of access in these population groups


Assuntos
Preservativos , Preservativos Femininos , Grupos Populacionais , Direitos Sexuais e Reprodutivos , Lubrificantes , Violência , Infecções Sexualmente Transmissíveis , HIV , Discriminação Social
18.
Bioprocess Biosyst Eng ; 44(11): 2429-2444, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34269888

RESUMO

The present study reports the effects of three commercial immobilized lipases namely Novozyme 435 from Candida antarctica lipase B (CALB), Lipozyme TL IM from Thermomyces lanuginosus and Lipozyme RM IM from Rhizomucor miehei on the production of trimethylolpropane (TMP) ester from high oleic palm methyl ester (HO-PME) and TMP. The TMP ester is a promising base oil for biolubricants that are easily biodegradable and non-toxic to humans and the environment. Enzymatic catalysts are insensitive to free fatty acid (FFA) content, hence able to mitigate the side reactions and consequently reduce product separation cost. The potential of these enzymes to produce TMP ester in a solvent-free medium was screened at various reaction time (8, 23, 30 and 48 h), operating pressure (0.1, 0.3 and 1.0 mbar) and enzyme dosage (1, 3, 5 and 10% w/w). The reaction was conducted at a constant temperature of 70 °C and a molar ratio of 3.9:1 (HO-PME: TMP). Novozyme 435 produced the highest yield of TMP ester of 95.68 ± 3.60% under the following conditions: 23 h reaction time, 0.1 mbar operating pressure and 5% w/w of enzyme dosage. The key lubrication properties of the produced TMP ester are viscosity index (208 ± 2), pour point (- 30 ± - 2 °C), cloud point (- 15 ± - 2 °C), onset thermal degradation temperature (427.8 °C), and oxidation stability, RPVOT (42 ± 4 min). The properties of the TMP ester produced from the enzymatic transesterification are comparable to other vegetable oil-based biolubricants produced by chemical transesterification.


Assuntos
Enzimas Imobilizadas/metabolismo , Lipase/metabolismo , Lubrificantes/metabolismo , Óleo de Palmeira/metabolismo , Propilenoglicóis/metabolismo , Catálise , Esterificação , Ésteres/metabolismo , Óleo de Palmeira/química
19.
AAPS PharmSciTech ; 22(4): 151, 2021 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-33977355

RESUMO

As commonly known, the product development stage is quite complex, requires intensive knowledge, and is time-consuming. The selection of the excipients with the proper functionality and their corresponding levels is critical to drug product performance. The objective of this study was to apply quality by design (QbD) principles for formulation development and to define the desired product quality profile (QTPP) and critical quality attributes (CQA) of a product. QbD is a risk- and science-based holistic approach for upgraded pharmaceutical development. In this study, Ibuprofen DC 85W was used as a model drug, Cellactose® 80 along with MicroceLac® 100 as a filler, and magnesium stearate, stearic acid, and sodium stearyl fumarate as lubricants. By applying different formulation parameters to the filler and lubricants, the QbD approach furthers the understanding of the effect of critical formulation and process parameters on CQAs and the contribution to the overall quality of the drug product. An experimental design study was conducted to determine the changes of the obtained outputs of the formulations, which were evaluated using the Modde Pro 12.1 statistical computer program that enables optimization by modeling complex relationships. The results of the optimum formulation revealed that MicroceLac® 100 was the superior filler, while magnesium stearate at 1% was the optimum lubricant. A design space that indicates the safety operation limits for the process and formulation variables was also created. This study enriches the understanding of the effect of excipients in formulation and assists in enhancing formulation design using experimental design and mathematical modeling methods in the frame of the QbD approach.


Assuntos
Química Farmacêutica/métodos , Força Compressiva , Desenvolvimento de Medicamentos/métodos , Lubrificantes/síntese química , Química Farmacêutica/normas , Composição de Medicamentos/métodos , Desenvolvimento de Medicamentos/normas , Ibuprofeno/síntese química , Ibuprofeno/normas , Lubrificantes/normas , Ácidos Esteáricos/síntese química , Ácidos Esteáricos/normas , Tensoativos/síntese química , Tensoativos/normas , Comprimidos , Resistência à Tração
20.
J Oleo Sci ; 70(6): 777-785, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33967171

RESUMO

Sesbania cannabina (Retz.) Pers. (Dhaincha) is a member of family Fabaceae spread over several countries in tropical and subtropical regions of the world. Sesbania aculeata, Sesbania drummondii, Sesbania grandiflora, Sesbania rostrata, Sesbania sesban, and Sesbania speciosa are other members of this family. The agricultural, nutritional and pharmaceutical applications of Sesbania species are known to farmers, villagers, and the tribes since ages and are well studied by researchers. However, the significance of Sesbania as an industrial crop has not been recognized till now. The objective of this study was extraction and characterization of Sesbania cannabina seed oil (SCSO) for potential engineering applications. The seed oil was extracted with hexane in a Soxhlet extractor. Yield was only 2.32% w/w due to long storage at high temperature in seed house. Sesbania cannabina seed oil methyl ester (SCSOME) was prepared via esterification and transesterification for analysis of fatty acid composition of extracted oil. SCSO has high iodine value (118 g I2/100 g) and high saponification value (185.79 mg KOH/g) making the oil suitable for use as candle stocks or in soap making. However, these applications were ruled out on account of being insignificant for oil available in limited quantity. The oil has high viscosity index (174.19), high onset (382°C) and offset (450°C) decomposition temperatures, endothermic nature, and shear rate thickening behaviour. These properties make SCSO a good candidate for application as specialty lubricant required under severe operating conditions of high temperature and high shear rate or as insulating and cooling transformer oil.


Assuntos
Óleos de Plantas/química , Sementes/química , Sesbania/química , Temperatura Alta , Lubrificantes/química , Lubrificantes/isolamento & purificação , Óleos de Plantas/isolamento & purificação , Viscosidade
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA