Use Of Glycerin Research Articles

Use of glycerin in strategies against Aedes aegypti mosquito

Use of glycerin in strategies against Aedes aegypti mosquito

Migration Studies and Endocrine Disrupting Activities: Chemical Safety of Cosmetic Plastic Packaging.

The endocrine activity and endocrine disruptor (ED) chemical profiles of eleven plastic packaging materials covering five major polymer types (3PET, 1HDPE, 4LDPE, 2 PP, and 1SAN) were investigated using in vitro cell-based reporter-gene assays and a non-targeted chemical analysis using gas chromatography coupled to mass spectrometry (GC-MS). To mimic cosmetic contact, six simulants (acidic, alkaline, neutral water, ethanol 30%, glycerin, and paraffin) were used in migration assays performed by filling the packaging with simulant. After 1 month at 50 °C, simulants were concentrated by Solid Phase Extraction (SPE) or Liquid-Liquid Extraction (LLE). The migration profiles of seven major endocrine disrupting chemicals detected from GC-MS in the different materials and simulants were compared with Estrogen Receptor (ER) and Androgen Receptor (AR) activities. With low extraction of ED chemicals in aqueous simulants, no endocrine activities were recorded in the leachates. Paraffin was shown to be the most extracting simulant of antiandrogenic chemicals, while glycerin has estrogenic activities. Overall, ED chemical migration in paraffin was correlated with hormonal activity. The NIAS 2,4-di-tert-butyl phenol and 7,9-di-tert-butyl1-oxaspiro (4,5) deca-6,9-diene-2,8-dione were two major ED chemicals present in all polymers (principally in PP and PE) and in the highest quantity in paraffin simulant. The use of glycerin and liquid paraffin as cosmetic product simulants was demonstrated to be relevant and complementary for the safety assessment of released compounds with endocrine activities in this integrated strategy combining bioassays and analytical chemistry approaches.

Proposal for a Circular Economy of glycerin as a by-product of biodiesel production

The Circular Economy of glycerin a proposal to reduce the environmental impact, the economic contribution, as well as avoid the discharge of used edible oils into bodies of water, the problems towards gray water treatment plants in the pretreatment process, in the landfill to prevent runoff from contaminating the soil, due to the type of Karstic soil in the region. Obtaining glycerin is one of the objectives of the project, part of the work is its application of fuel cells, as an alternative source of renewable energy. The proposed methodology Circular Economy of glycerin by-product obtained from biodiesel and the uses derived from it, the economic contribution and sustainability of this. As a result, obtaining an environmental, economic benefit, which requires both compliance with environmental laws and regulations, letting the population of the northern area of Quintana Roo know that there are alternative places to the pipes, throwing it in garbage bags where they deposit their used oil, the use of glycerin as a component livestock feed supplement as soil fertilizers and use in the generation of biogas.

УПРАВЛІННЯ ПРОЦЕСАМИ СТРУКТУРОУТВОРЕННЯ ШЛАКОЛУЖНИХ ЦЕМЕНТІВ, АКТИВОВАНИХ СИЛІКАТАМИ НАТРІЮ

The article discusses approaches to the formation of the composition of slag-alkali cements when using high-modulus solution glass as an alkaline component, represented by a commercial product in the form of a liquid. The aim of this work was to study the effect of modifying additives, the silicate module of sodium hydrosilicates and technology modes on the processes of structure formation of artificial cement stone for effective control of setting time, intrinsic shrinkage deformations and achievement of high compressive strength (≥80 MPa at a standard age of 28 days and ≥ 20 MPa after 3 hours curing under normal conditions). As a result of the studies performed, a positive effect on the use of glycerin additives as part of a complex additive on the formation of the structure and properties of artificial stone was established. It is noted that the use of the studied modifying additives contributes to an increase in the degree of slag hydration, the formation, along with hydrosilicate compounds, of xerogel structures and celite-like compounds, which are deposited on the hydrosilicate-based matrix in the form of blocks-aggregates and increase the total volume of structure-forming compounds. A positive synergistic effect of using glycerin as an additional modifying component of the "trisodium phosphate + glycerin" complex additive for controlling the setting time in slag-alkali cements based on high-modulus solution glasses has been established. This made it possible to extend the time for the start of setting of slag-alkali cements when using solution high-modulus glasses from 3…5 min. up to values 26…83 min. Received cements with compressive strength after 3 hours 16.7...23.1 MPa, after 1 day 34.1...38.2 MPa, after 28 days 86.2...117.1 MPa with acceptable terms start of grasping. The heat release of such cements after 72 hours, despite their high activity, is only 150...180 J/h, which is 1.7...2 times less than that of fast-hardening Portland cement grade 600 and 2...2.4 alumina cement. Intrinsic shrinkage strains of compositions with modifying additives at the moment of stabilization were equal to 0.5…0.6 mm/m.

Acute Kidney Injury Following Mannitol Infusion in Neurosurgical Patients

Background: To evaluate the acute kidney injury (AKI) predictors and their predictive performance during mannitol infusion, and the impact of AKI on in-hospital mortality of neurocritically ill patients.Methods: This was a retrospective, observational study of patients who were admitted at a tertiary university hospital, Seoul, Republic of Korea, neurosurgical intensive care unit (ICU) from January 2013 to December 2019. We included neurosurgical patients on mannitol infusion admitted in the ICU The primary endpoint was the occurrence of AKI.Results: A total of 3,964 patients were included in the final analysis. AKI was detected in 540 (13.6%) patients on mannitol infusion. Measured osmolality and osmolar gap were significantly higher in patients with AKI than those without (both p< 0.001). However, the predictive power of the two indicators was similar and were both weak predictors of AKI (both C-statistic <0.650). In the multivariable analysis, maximal measured osmolality, chronic kidney disease, Acute Physiology and Chronic Health Evaluation 2 score on ICU admission, use of vasopressor, use of glycerin, mechanical ventilation, and invasive ICP monitoring were significantly associated with AKI. In-hospital mortality was significantly higher in patients with AKI than those without (11.1% vs. 1.4%, p< 0.001).Conclusions: Based on our findings, kidney injury may be associated with poor clinical outcomes in neurosurgical and neurocritically ill patients, and monitoring serum osmolality and OG remains important in the prevention of kidney injury for patients on mannitol infusion. Moreover, clinical factors related to ICU management and pre-existing renal disease may aggravate AKI during mannitol infusion.

Development and characterization of low metallic friction composites filled with brass chips

ABSTRACT This research is focused on investigating new low metallic non-asbestos organic friction composite materials obtained by conventional powder metallurgy techniques. Three different composite mixtures were prepared by varying brass concentrations 1.5, 2.0 and 2.5 wt-% using the glycerin as a plasticizer. The prepared brake pad materials were subjected to density, hardness, thermal stability, friction and specific wear rate analysis. Tribological properties of friction specimen were studied on pin-on-disc type friction testing machine model MMW-1 using nominal contact pressure 7.69 MPa, sliding velocity 1.74 m/s and 1.57 km sliding distance conditions. Microstructural characterization of worn surfaces was carried out using scanning electron microscopy. Obtained test results indicate that brass chips have an important effect on improving tribo-performance. Physical–mechanical characterization of friction composites showed that the use of glycerin improves the physical properties of materials by improving the powder compressibility and reducing the structural defects formed by brass chips.

Glycerin supplementation strategies for three or seven days affects oxidative stress, follicle dynamics and ovulatory response in Morada Nova sheep.

This study examined the effect of glycerin supply strategies in different short-term protocols on follicular dynamics and ovulatory rate in Morada Nova sheep. Eighteen Morada Nova ewes with body condition > 2.9 had their estrus and follicular waves synchronized using three injections of prostaglandin analogue at seven-day intervals. All animals received the same diet during 21 days, which consisted of a total mixed ration (TMR) based on chopped elephant grass and concentrate twice daily. In the control group (n=9), ewes were fed the TMR diet. In the other four groups, ewes received 150 mL of glycerol daily, supplied as an oral drench or mixed in the TMR during three or seven days prior to the application of the third PGF2 alfa analogue. These groups were named as follows: Drench3d (n=10), Drench7d (n=8), TMR3d (n=9) and TMR7d (n=9). Follicle dynamics were monitored by ultrasonography, and plasma glucose and glutathione peroxidase levels were measured at the third prostaglandin administration. Six days after the final PGF2 alfa analogue dose, ovulatory rate was measured by laparoscopy. Glucose was higher (P< 0.001) in the glycerin-treated groups than in control group (83.7 ± 1.7 vs. 68.4 ± 4.5 mg. dL-1; P < 0.001). Ewes in the TMR3d, Drench7d and TMR7d groups had a greater (P < 0.001) number of large follicles (≥ 3 < 5 mm), and the presence of follicles larger than 5 mm was observed. In the same groups, at the third PGF2 alfa analogue dose, a greater (P < 0.001) number of growing follicles (> 3 mm) and a larger size of the largest follicle (P < 0.001) were also recorded. Ovulation rate was 30% higher in the groups that received glycerin for seven days (1.6 ± 0.1 53 vs. 1.1 ± 0.1; P < 0.05), and they also exhibited a 38% reduction in glutathione peroxidase. Thus, the use of glycerin in Morada Nova sheep as a source of energy in short-term supplementation for increase ovulation rate is an efficient strategy when provided for seven days, either orally or in the feed.

Benefit of Glycerine on Surface Hardness of Hybrid &amp; Nanofill Resin Composite

Background: Composite resins restoration is a treatment for tooth structure loss due to pathological conditions. Longevity of composite resins restoration can be affected by surface hardness restoration. Glycerin can increase surface hardness restoration with inhibit bond oxygen and free radicals on polymerization composite resins. Purpose: Analyze the increase surface hardness composite resins restoration after glycerin application before light-curing composite resins. Review(s): Of the six journals included in this literature review, five journals reported significant differences because of the obstacles in the polymerization process of the composite resin when composite contact with light-curing will activate the photoinitiator to produce highly reactive free radicals, free radicals will break the double chain carbon bonds of monomers and form single bonds of free radicals with monomers. Bonding of free radicals with monomers will produce polymeric bonds (degree of conversion) which affects the level of surface hardness of the filling. While one journal noted no significant difference in the surface hardness of composite resin after glycerin application. Conclusion: The use of glycerin before light-curing can increase the surface hardness composite resin restorations.

Evaluation of an alternative technique for preserving crustaceans in dry conditions with joint mobility: a proposal for didactic purposes

Although crustaceans are traditionally preserved in liquids (formaldehyde and/or ethyl alcohol), those substances tend to alter their morphological aspects. Glycerin, used in human anatomy, is considered a good substitute for formaldehyde, as it preserves animals in states similar to in vivo conditions. There are no records in the literature, however, concerning the use of glycerin for conserving invertebrates. The objective of this work was to elaborate and evaluate alternative techniques for conserving the crustacean Ucides cordatus (Linnaeus, 1763). Six fixatives (1, 3, 4 and 5% formaldehyde, 70% alcohol, and dietrich solution) and two controls (positive and negative) were tested, as well as the effects of freezing before fixation on the integrity of U. cordatus specimens. Our results were evaluated with respect to nine variables. The treatments that demonstrated the best aesthetic results were 4% formaldehyde and 70% ethyl alcohol. The freezing of the animals resulted in brittle organs in all treatments tested. The technique discussed here is extremely promising for the conservation of animals for educational purposes, as it produces preserved specimens that are aesthetically similar to their in vivo conditions.

Decrease of microbial contamination by application of routinely glycerol and phenol solution on human cadavers

Human cadaver is imperative learning material for medical students. The cadavers expose to microbial contamination every time anatomists work with them. The microorganisms found in preparations’ cadavers could be pathogenic. Although the cadaver has supported a preservation method but does not inhibit microbial germination. The purposes of this study were evaluation the use of the routine solution to decrease potential contamination. Samples were collected air dissection hall and cadavers' sections after drying the cadavers, and after use of routinely glycerin and phenol solution (1.5 g phenol in 100 cc glycerol), inoculated on eosin methylene blue agar (EMB), blood agar (BA), Sabouraud dextrose agar (SDA), and SDA with the addition of chloramphenicol (50 mg/l in ethanol solution) (SC), in a Petri dish and incubated at 25 °C and 37 °C. After 3-5 days, the morphology was studied macroscopically and microscopically. We found Sporothrix schenckii ; Streptomyces , Bacillus subtilis and Aspergillus flavus , Geotrichum candidum , on the samples of dryness cadavers and air dissection hall, respectively. But fungus and bacteria contamination was decreased after the use of glycerin and phenol solution. Based on the results of this study, it is suggested that glycerol and phenol solution can be used at least once a week to reduce microbial contamination and prevent the spread of the disease from the cadavers to students and professors.

Meta-analysis of the effect of glycerin inclusion in dairy cattle diet on milk fatty acid profile.

The use of glycerin in diets for dairy cows initially emerged as an alternative for the prevention and control of ketosis. However, despite some controversy, there are still several studies associating glycerin with increases in daily milk yield, with possible changes in its constituents. Therefore, the objective of this study was to evaluate, using a meta-analysis approach, the effect of glycerin inclusion in dairy cow diets on milk fatty acid. Twenty-two peer-reviewed publications with 66 treatment means were included in data set. The effect of glycerin inclusion in diet (treatment) were evaluated using random-effect models to examine the weighted mean differences (WMD) between a control diet (without glycerin in the diet) and the treatment diet. Heterogeneity was explored by meta-regression and subgroup analysis performed for: genetic type; days in milk; experimental period; glycerin in diet; glycerin type and concentrate in diet. Inclusion of glycerin in the diet increased the digestibility of dry matter and protein, as well as ruminal propionate. It did not affect dry matter intake (P = 0.351) and milk yield (P = 0.730). The effect of glycerin inclusion on the milk fat yield is dependent on the genetic group, in which Holstein (WMD = −0.04 kg/d; P = 0.010) and Holstein-crossbreed (WMD = −0.10 kg/d; P < 0.0001) cows produced less fat in milk compared to Jersey cows, when glycerin was included in the diets. Glycine inclusions of up to 100 g/kg in the diet of dairy cows did not negatively affect milk production and composition. However, inclusions above 150 g/kg of glycerin in the diet reduced the concentration of fat, and of unsaturated, monounsaturated, polyunsaturated fatty acids and conjugated linoleic acid (CLA C18: 2 cis-9 and trans-11) in milk. The results reported in our meta-analysis does not demonstrate the effectiveness of glycerin in improving the composition of milk and a group of fatty acids of importance for human health such as C18: 2 cis-9, trans-11 CLA.

Excitation of labor by intrauterine injections of glycerin

Having briefly examined the existing methods of initiating artificial premature labor and finding them not entirely appropriate and safe for the mother and the fetus, the author cites his observations on the use of glycerin in the Cologne obstetric institution in order to excite and enhance the labor of the uterus: from the given birth histories, it is clear that intrauterine injections glycerol, this goal is achieved quickly, without the slightest harm to the mother or fetus, and without any change in the usual mechanism of childbirth, and glycerin, over other commonly injected liquids, has a great advantage in its antiseptic properties.

Glycerin-Assisted Vitreoretinal Surgery in Edematous Cornea.

To describe the use of glycerin in improving media clarity in cases with edematous cornea. Retrospective case series including patients with posterior segment pathologies needing surgical invention and having corneal edema. Each case was studied for the role of topical application of glycerin instead of viscoelastic agents and the course of surgery. The cases were followed up for minimum 3 months duration. Six cases with corneal edema having posterior segment pathology underwent surgery with intraoperative topical application of glycerin. The corneal edema was seen to clear with progression of surgery and was maintained until the end of surgery. Procedures such as vitreoretinal surgery, identification of break, internal limiting membrane peeling, intraocular lens explantation, scleral indentation, Descemet stripping endothelial keratoplasty graft removal, and subretinal band removal could be performed in these cases. Intraoperative glycerin use during vitreoretinal surgeries is helpful in improving the corneal clarity and maintaining it till the end of surgery.

INVESTIGATION OF THE INFLUENCE OF GLYCERIN ON RHEOLOGICAL CHARACTERISTICS OF MARZIPAN PASTES WITH DRY MINERALIZED WHEY

There is studied the influence of glycerin on rheological characteristics of marzipan pastes with dry demineralized whey (DDW) for determining its rational concentration in the composition of decorative semi-products PKV and MFV. PKV – marzipan pastes with DDW, used for covering confectionary products and as an interlayer; MFV – marzipan pastes with DDW, used for making candies and modeling figured products. According to research results, it has been established, that an increase of a glycerin concentration in the composition of model mixtures of marzipan pastes PKV (20 % of DDW) and MFV (30 % of DDW) results in decreasing deformation characteristics of a reversible type. Irreversible deformation is constant and doesn’t depend on glycerin concentration. According to results of the analysis of main rheological constants by a diapason of glycerin concentrations, there has been established a gradual decrease of indices of a highly elastic and conventionally instant resilience module of model compositions of marzipan pastes PKV (20 % of DDW) and MFV (30 % of DDW). Viscosity indices of a resilient aftereffect and pliability gradually grow with an increase of a glycerin concentration in the composition of model marzipan pastes PKV (20 % of DDW) and MFV (30 % of DDW). Research results testify that the use of glycerin in the composition of marzipan pastes PKV (20 % of DDW) and MFV (30 % of DDW) gives a possibility to increase their elasticity and softness, at that keeping high forming properties. The conducted studies have proved the availability of producing marzipan pastes with DDW and glycerin. There has been substantiated the rational content of glycerin in the composition of marzipan pastes with DDW that allows to provide given (desirable) rheological characteristics. The rational concentration of glycerin in the composition of marzipan pastes PKV (20 % of DDW), used for covering floury and confectionary products and as an interlayer is 5 % of the total mass of recipe components. The rational concentration of glycerin in the composition of marzipan pastes MFV (30 % of DDW), used for making candies, modeling figured products is 5 % of the total mass of recipe components. An improved technological solution doesn’t complicate the general technological process and doesn’t need the additional technical equipment. Rheological characteristics of the developed marzipan pastes correspond to directions of the technological destination and allow to decorate floury confectionary products with different levels of technological complication, providing the maximal beauty of ready products.

Feeding plans with the use of glycerin for broilers

This study aimed to evaluate the effects of feeding plans with or without addition of glycerin, in different ages, on performance, carcass yield, litter moisture and footpad lesions of broiler chickens. 540 male Cobb broilers were utilized, distributed in a completely randomized design with six treatments (treatments consisted of the inclusion or not of glycerin in diets at all periods or only at different stages: 1 to 7, 8 to 21, 22 to 33 and 34 to 42 days), in six replicates of 15 birds each. Diets were provided ad libitum. At 42 days, the average weight, weight gain, feed intake, feed conversion, carcass yield, litter moisture and footpad lesions were evaluated. There was no effect (p&gt; 0.05) of dietary plans on the performance variables. The feeding plans did not influence (p&gt;0,05) the carcass and cuts parameters at 42 days. However, there was significant effect (p &lt;0.05) of the dietary plans on litter moisture and plantar lesions. Effects were observed (p&gt;0,001) for the feeding plans, were the highest and the lowest incidence of lesions were present in the birds that consume diets with and without addition of glycerin, in the period from 1 to 42 days of age, respectively.

Glicerina bruta como alimento energético para vacas de leite

A glicerina bruta é um resíduo oriundo da produção de biodiesel. Com o aumento da demanda por biodiesel nos últimos anos, houve também um aumento na produção de glicerina, um co-produto que não é utilizado pelas indústrias. Assim, novas alternativas podem ser viáveis, como o uso na alimentação de vacas leiteiras. O uso da glicerina na dieta dos animais demonstra ser uma alternativa viável no que diz respeito aos aspectos nutricionais e econômicos. Nosso objetivo nesta revisão foi abordar a utilização da glicerina em dietas de vacas leiteiras e seus possíveis efeitos sobre a produção de leite. Em vários estudos, é possível observar que a glicerina bruta pode ser incluída na dieta de ruminantes sem causar efeitos negativos sobre o metabolismo, fermentação ruminal e produção de leite. Estudos sobre os efeitos deletérios da inclusão de glicerina em bruto com alto teor de metanol na dieta de vacas leiteiras devem ser realizados.

Next-generation diamond cell and applications to single-crystal neutron diffraction.

A diamond cell optimized for single-crystal neutron diffraction is described. It is adapted for work at several of the single-crystal diffractometers of the Spallation Neutron Source and the High Flux Isotope Reactor at the Oak Ridge National Laboratory (ORNL). A simple spring design improves portability across the facilities and affords load maintenance from offline pressurization and during temperature cycling. Compared to earlier prototypes, pressure stability of polycrystalline diamond (Versimax®) has been increased through double-conical designs and ease of use has been improved through changes to seat and piston setups. These anvils allow ∼30%-40% taller samples than possible with comparable single-crystal anvils. Hydrostaticity and the important absence of shear pressure gradients have been established with the use of glycerin as a pressure medium. Large single-crystal synthetic diamonds have also been used for the first time with such a clamp-diamond anvil cell for pressures close to 20 GPa. The cell is made from a copper beryllium alloy and sized to fit into ORNL's magnets for future ultra-low temperature and high-field studies. We show examples from the Spallation Neutron Source's SNAP and CORELLI beamlines and the High Flux Isotope Reactor's HB-3A and IMAGINE beamlines.

Physical properties of NaCl-free cucumber fermentation cover brine containing CaCl2and glycerin and apparent freezing injury of the brined fruits

Use of glycerin and CaCl2 to reduce the freezing point and improve quality of bulk stored fermented cucumbers brined without NaCl, was explored. The incidence of pre-freezing injury on the fruits, caused by deposition in tanks containing cushion brine prepared with 2.5% CaCl2, was excluded by determining the liquid and fruits densities and buoyancy force. The NaCl-free cover brine thermal properties and freezing point, and the frozen fruits water loss were determined to estimate freezing damage. Cover brines supplemented with 14.5% glycerin, 18% CaCl2, or 14% glycerin and 5% CaCl2 were needed to match the freezing point of the 6% NaCl cover brine, typically used for fermentation. Thermal properties of the NaCl-free cover brine were insignificantly affected by temperature or composition. Water loss was the main freezing injury in brined cucumbers. Supplementation of CaCl2 and/or glycerin in fermentation cover brines helped minimize fermented cucumbers water loss associated with freezing. Practical applications This study presents an assessment of brine composition that can prolong processed pickle quality and bulk storage at temperatures below zero. Fermented cucumbers stored in cover brine containing 14.5 vol % glycerin, 18 wt % CaCl2, or 14 vol % glycerin and 5 wt % CaCl2 have a reduced freezing point, which theoretically extends the window for acceptable product quality. The use of 14% glycerin above the cover boards to reduce the freezing point and, consequently, ice formation on the surface of the open-top tanks is to enable the removal of fermented fruits during winter with minimal tissue injury.

Evaluation of Lubricating Properties of Diesel Based Fuels Micro Emulsified With Glycerin

The mineral diesel oil sold in Brazil, due to environmental reasons; presents sulfur concentration of 10 ppm, which causes a deficiency of lubricity, since sulfur is one of the chemical species that gives a good lubricating characteristic. Poor lubricity affects performance and causes failure of engine parts. This study aimed to evaluate the use of glycerin as an antiwear additive by means of tribological tests of the mineral diesel S10 B7 and 10 formulations of diesel based fuels, micro emulsified with 0% (distilled water), 7.5% and 15% of glycerin solution. The formulations were subjected to lubricity tests on HFRR (Hight Frequency Reciprocating Rig) under hydrodynamic lubrication conditions, according to the ASTM D-6079 standard. The results showed that the increased concentration of glycerin added to diesel S10 B7 contributes to improved lubricity and wear reduction

Produção e utilização da glicerina bruta na alimentação de frangos de corte

A glicerina bruta (GB) é um coproduto gerado no processo de produção do biodiesel, do qual representa 10% do produto final. A utilização da GB na alimentação de animais não-ruminantes torna-se interessante, pois apresenta um alto teor de energia bruta e, ainda, a sua utilização pode proporcionar o retorno de parte das matérias-primas empregadas na produção de energia à cadeia alimentar, dando origem a produtos de elevado valor nutritivo. O emprego da glicerina na sua forma bruta como alimento energético vem sendo estudado como uma alternativa para a redução do custo com a alimentação animal, além de proporcionar um destino ambientalmente correto a esse coproduto. Porém, os valores enérgicos e a composição da GB, encontrados na literatura, apresentam grande variação, porque no processo de produção do biodiesel podem ser utilizadas diferentes matérias primas bem como diferentes processos. Além disso, a GB pode apresentar altas concentrações de metanol e sal (sódio ou potássio), devido a utilização do metanol e hidróxido de sódio ou potássio durante o processo de produção do biodiesel. Neste contexto, é necessário o entendimento da capacidade da utilização da GB e seus possíveis efeitos adversos em frangos de corte. Perante estes factos, o objetivo desta revisão é caracterizar a GB como um alimento alternativo para frangos de corte, bem como os fatores que devem ser avaliados antes da sua utilização.