RESUMEN

Advances in high-pressure grinding roll (HGPR) technology since its first commercial application in the cement industry include new roll wear protection techniques and new confinement systems. The latter contribute to reductions in the edge effects in an attempt to reach a more homogenous product size along the rolls. Additional advances in this technology have been made in recent years, while modeling and simulation tools are also reaching maturity and can now be used to subject such novel developments to detailed scrutiny. This work applies a hybrid approach combining advanced simulations using the discrete element method, the particle replacement model and multibody dynamics to a phenomenological population balance model to critically assess two recent advances in HPGR technology: spring-loaded cheek plates and the offset roller press. Force and torque controllers, included in the EDEM 2022.1 software, were used to describe the responses of the geometries in contact with the granular material processed. Simulations showed that while the former successfully reduced the lateral bypass of the material by as much as 65% when cheek plates became severely worn, the latter demonstrated lower throughput and higher potential wear but an ability to generate a finer product than the traditional design.

RESUMEN

PURPOSE: To describe a novel surgical technique aimed to approach those orbital lesions located superior and posterior to the equator of the globe. METHODS: We describe a novel surgical technique that was performed in four patients to approach intraorbital tumors superiorly and posteriorly located. This technique was completed through an upper eyelid skin crease followed by grinding the superior orbital rim to achieve complete removal of the lesions. RESULTS: Complete removal of the lesion was accomplished in every case. No intraoperative complications were observed in any of the patients. During the follow-up period, one patient presented with frontal hypersensitivity and one with diplopia. CONCLUSIONS: In the case series presented, the upper eyelid skin crease approach with grinding of the superior orbital rim proved to be a safe and effective surgical technique to remove lesions located superior and posterior within the orbit in our series. More studies are needed to further evaluate the efficacy and long-term results of this approach.

RESUMEN

Particle size and storage time are factors that can affect the fermentation quality and digestibility of rehydrated corn grain silage (RCS). The objective of this study was to evaluate the effect of particle size and storage time on chemical and microbiological characteristics, aerobic stability, and ruminal degradability of RCS. Corn grains were ground to pass through either a 3 mm (fine) or 9 mm (coarse) screen, rehydrated to 44.3% moisture and ensiled in 200 L polyethylene buckets. Samples were taken before and after ensiling at 10, 30, 90 and 200 days of storage to assess microbial counts, fermentation end products, and DM ruminal degradability. DM degradation was evaluated with incubation times of 0 (bag wash), 3, 6 and 48 h in 3 rumen-cannulated cows. The effective ruminal degradation (ERD) was calculated based on soluble fraction (A), degradable fraction (B) and passage rate (kp) defined as 7.0%/h: A + B [kd/(kd + kp)]. Aerobic stability was evaluated in silages after 200 days of storage, and pH and temperature were analysed up to 240 h of aerobic exposure. At 90 and 200 d of storage, fine RCS resulted in lower crude protein and greater NH3-N concentrations than coarse RCS. Coarsely ground RCS had a lower temperature at the beginning of storage than finely ground corn. Finely ground RCS had greater yeast counts and ethanol concentrations than coarsely ground RCS during storage time. Fine RCS was more susceptible to aerobic deterioration, reaching maximum temperature and pH values faster than coarse RCS. DM ruminal degradability increased over the storage time. The particle size of the rehydrated corn grain silage did not affect the kd values after 90 d of storage, while for the ERD, a long fermentation time was necessary (200 d). Considering the fermentation characteristics and the kinetics of ruminal DM degradation, fine grinding is recommended for short storage periods and coarse grinding may be a strategy to increase the rate of grinding when the storage period is greater than 200 d.

Asunto(s)

RESUMEN

Sulfamethazine [N1-(4,6-dimethylpyrimidin-2-yl)sulfanilamide] is an antimicrobial drug that possesses functional groups capable of acting as hydrogen-bond donors and acceptors, which make it a suitable supramolecular building block for the formation of cocrystals and salts. We report here the crystal structure and solid-state characterization of the 1:1 salt piperidinium sulfamethazinate (PPD+·SUL-, C5H12N+·C12H13N4O2S-) (I). The salt was obtained by the solvent-assisted grinding method and was characterized by IR spectroscopy, powder X-ray diffraction, solid-state 13C NMR spectroscopy and thermal analysis [differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA)]. Salt I crystallized in the monoclinic space group P21/n and showed a 1:1 stoichiometry revealing proton transfer from SUL to PPD to form salt I. The PPD+ and SUL- ions are connected by N-H+...O and N-H+...N interactions. The self-assembly of SUL- anions displays the amine-sulfa C(8) motif. The supramolecular architecture of salt I revealed the formation of interconnected supramolecular sheets.

RESUMEN

The aim of the study was to evaluate the methodological quality and the risk of bias of systematic reviews with regard to the literature on therapies for sleep bruxism (SB) in dentistry, applying the AMSTAR 2 (A MeaSurement Tool to Assess systematic Reviews) qualitative guide, as well as the effectiveness of various kinds of treatment of SB. Initially, a total of 1,499 articles were obtained from 4 databases and 2 websites. Relevant articles were obtained from the PubMed, Scopus, Cochrane, and Embase databases as well as from Google Scholar and OpenGrey. Six systematic reviews that met the eligibility criteria were included. The methodological quality of all systematic reviews, assessed with the AMSTAR 2 tool, was critically low. Regarding treatment effectiveness, 5 systematic reviews reported on pharmacological management (botulinum toxin type A (BTX-A), clonazepam and clonidine), 2 reported on oral appliances (OAs) (stabilizing splints and mandibular advancement devices (MADs)) and 1 study addressed the effects of biofeedback (BF). The results of the therapies were diverse and confusing. The available research is not conclusive, and does not show clear evidence or a consensus on the part of researchers on the most effective treatment for the management of SB. More research of better methodological quality is needed in this area.

Asunto(s)

RESUMEN

In the rapid development of organic light-emitting diodes (OLEDs), phosphorescent transition metal complexes have played a crucial role as the most promising candidates for next generation display and lighting applications. However, most devices are fabricated using iridium and platinum-based complexes which are expensive and available in very limited quantities, whereas using relatively abundant organometallic complexes for fabrication results mostly in inefficient performance results. To overcome these issues, we have synthesized tetra copper iodide with tetra triphenyl cage like structure (denoted as CIPh) as an emerging class of luminescent material by mechanochemical grinding followed by thermal treatment for application in white OLED. The CIPh complex exhibits considerable quantum yield and a millisecond decay lifetime. Phosphorescent OLEDs were fabricated using CIPh complex as emitter shows a remarkable performance with external quantum efficiency and current efficiency of 5.28 % and 22.76 cd/A, with a high brightness of 4200 cd m-2, respectively. White OLEDs were also fabricated with a fluorescent blue and phosphorescent red emitted with (CIPh) as green emitter and achieved an impressive CRI of 82 with an EQE of over 3 %. This is the first ever attempt at fabricating WOLEDs using organocopper complex.

RESUMEN

BACKGROUND: 1,3-Thiazolidin-4-ones are heterocycles whose importance in the pharmaceutical market has already been established. Many of these synthetic derivatives, which contain a thiazolidinone nucleus, are currently used in various commercial formulations or are already in clinical trials for the treatment of disease for their anticonvulsant, antihypertensive and antidiabetic activities in addition to their activity against Streptomyces. 1,3-Thiazolidin-4-ones are produced mainly by cyclo condensation between an imine (generated in situ by the reaction of an aldehyde with an amine) and α-mercaptoacetic acid, known as the MALI (Mercaptoacetic Acid Looking Imine) reaction. OBJECTIVE: A solvent-free methodology was developed to synthesize a 1,3-thiazolidin-4-one family by the MALI reaction. An apparatus was developed to grind a solid-liquid mixture of anilines, benzaldehydes and thioglycolic acid to activate the reaction. This apparatus was named MGRE (mechanical grinding reaction equipment). METHODS: Substituted aniline 2 (4 mmol), substituted benzaldehyde 1 (4 mmol) and thioglycolic acid 3 (12 mmol) were placed in a mortar. The reagents were macerated using the MGRE at room temperature for a specified time period. At the end of the reaction, the product was poured into ice, the precipitate formed was neutralized (with 5% NaHCO3), and the solution was extracted in ethyl acetate and dried in MgSO4. The solid was recrystallized from MeOH/H2O. RESULTS: The developed MGRE is a modification of a rod used in a mechanical stirrer. This adaptation is inexpensive and simple in construction, and it enables reactions to occur over long periods of time that would be exhaustive for manual grinding. Fifteen (1,3) thiazolidin-4-ones were produced. The products were synthesized using the solvent-free MALI-MGRE procedure. CONCLUSIONS: The MALI-MGRE methodology developed to produce 1,3-thiazolidin-4-ones showed a good reaction scope, has an easy work-up and is solvent-free. Consequently, MALI-MGRE is classified as a green methodology. An innovation of this study is the construction of the MGRE, which involves modifying the rod in a mechanical stirrer. The equipment is easy and inexpensive to construct and may be useful for various reactions involving grinding.

RESUMEN

Objective: To evaluate the effect of the laterotrusive occlusal scheme on chewing duration, external intercostal (EIC) electromyographic (EMG) activity, heart rate (HR), and oxygen saturation (OS) during different tasks in the upright seated position.Methods: Fifty young participants, 25 with canine guidance and 25 with group function, were included. Chewing duration, bilateral EIC EMG activity, HR, and OS were recorded during the following tasks: 1) chewing until swallowing threshold; 2) laterotrusive teeth grinding.Results: Chewing duration, bilateral EIC EMG activity, HR, and OS showed no significant differences between the two laterotrusive occlusal schemes during the tasks studied.Conclusion: These results suggest that chewing duration, EIC muscle activity, HR, and OS were not significantly influenced by the laterotrusive occlusal scheme. Therefore, when a modification of the laterotrusive occlusal scheme is needed during oral rehabilitation or orthodontic treatment, canine guidance or group function should not significantly change EMG activity of EIC muscles.

Asunto(s)

RESUMEN

ABSTRACT Introduction: Bruxism is defined as a repetitive activity of masticatory muscles, characterized by the clenching or grinding of the teeth, which can occur during wakefulness (awake bruxism) or during sleep (sleep bruxism). Objectives: The objectives of the present study were to determine the prevalence of awake bruxism and its associated factors. Methods: Sample was composed by 50 participants of both genders, aged between 18 and 60 years, submitted to a clinical examination - to observe the presence of tooth wear, marks on the mucosa, or masseter muscles hypertrophy - and self-applied questionnaires, which evaluated the presence of TMD signs and symptoms, oral behaviors, lifestyles, anxiety level and sleep quality. Results: The prevalence of awake bruxism was 48%. Its presence was statistically and significantly associated with the presence of signs and symptoms of TMD (p=0.002), poor sleep quality (p=0.032), buccal mucosa indentations (p<0.001) and tongue (p=0.011). Age, gender, social characteristics, habits (such as coffee ingestion, smoking, alcoholism and physical activity) and tooth wear were variables that had no significant association with awake bruxism. Conclusions: It was concluded that awake bruxism shows a high prevalence and a positive association with signs and symptoms of TMD and worst sleep quality. In addition, awake bruxism is more likely to occur in individuals who have buccal mucosa indentation and who present high rates of oral habits and oral behaviors.

RESUMO Introdução: O bruxismo é definido como a atividade repetitiva dos músculos mastigatórios, e pode ocorrer durante o período acordado (bruxismo em vigília) ou durante o sono (bruxismo do sono). Objetivo: O presente estudo teve como objetivo avaliar a prevalência de bruxismo em vigília e seus fatores associados. Métodos: A amostra foi composta por 50 participantes, de ambos os sexos, com idades de 18 a 60 anos, avaliados por meio de minucioso exame clínico - para observar se havia presença de sinais como desgaste dentário, indentações na mucosa, hipertrofia do músculo masseter - e de questionários autoaplicáveis que visaram avaliar a presença de sinais e sintomas de disfunção temporomandibular (DTM), os comportamentos orais e hábitos de vida, o nível de ansiedade e a qualidade de sono dos participantes. Resultados: A prevalência de bruxismo em vigília foi de 48%. Sua presença foi associada, estatística e significativamente, com a presença de sinais e sintomas de DTM (p=0,002), má qualidade do sono (p=0,032), e indentações na mucosa jugal (p<0,001) e língua (p=0,011). Por outro lado, a idade, sexo, características sociais, hábitos (como ingestão de café, fumo, álcool e prática de atividade física), e o desgaste dentário foram variáveis que não tiveram associação com o bruxismo em vigília. Conclusão: Diante disso, conclui-se que o bruxismo em vigília possui uma prevalência significativa e uma associação positiva com DTM e qualidade do sono. Além disso, o bruxismo em vigília apresenta maior probabilidade de acontecer em indivíduos com indentação de mucosa jugal e com alta prevalência de hábitos e comportamentos orais.

RESUMEN

The prospect of growth of a railway system impacts both the network size and its occupation. Due to the overloaded infrastructure, it is necessary to increase reliability by adopting fast maintenance services to reach economic and security conditions. In this context, one major problem is the excessive friction caused by the wheels. This contingency may cause ruptures with severe consequences. While eddy's current approaches are adequate to detect superficial damages in metal structures, there are still open challenges concerning automatic identification of rail defects. Herein, we propose an embedded system for online detection and location of rails defects based on eddy current. Moreover, we propose a new method to interpret eddy current signals by analyzing their wavelet transforms through a convolutional neural network. With this approach, the embedded system locates and classifies different types of anomalies, enabling an optimization of the railway maintenance plan. Field tests were performed, in which the rail anomalies were grouped in three classes: squids, weld and joints. The results showed a classification efficiency of ~98%, surpassing the most commonly used methods found in the literature.

Asunto(s)

RESUMEN

The effect of micronization of granulometrically fractionated olive pomace (OP) on the bioaccessibility of polyphenols and the antioxidant capacity was investigated during sequential in vitro static digestion. Crude OP was fractionated in a 2-mm sieve (F1: > 2 mm; F2: < 2 mm) and then micronized (300 r min-1, 5 h) generating F1AG (17.8 µm) and F2AG (15.6 µm). Micronization increased the release of hydroxytyrosol, oleuropein, caffeic acid, and decarboxymethyl oleuropein aglycone (3,4-DHPEA-EDA) in the salivary and gastric phase, beyond luteolin in the gastric phase. Micronization also increased the intestinal bioaccessibility of hydroxytyrosol, 3,4-DHPEA-EDA, oleuropein, luteolin, and apigenin; it was more effective for F2AG than F1AG. Micronized samples increased antioxidant capacity in the gastric phase. F2AG exhibited the highest antioxidant capacity in the insoluble intestinal fraction. Thus, micronization can be further exploited to improve the nutraceutical properties of OP by increasing the bioaccessibility and antioxidant capacity of phenolic compounds.

Asunto(s)

RESUMEN

BACKGROUND: This article aims to present the results of a literature review on food milling, to identify the most recent uses, types of mills, and new grinding trends. METHODS: For this, a search was made with the keywords "grinding", "milling" and "food" in the Scopus, which yielded 192 articles, 52 of which directly related to food, were analyzed. RESULTS: Contributions were found related to various types of grinding such as cryogenic grinding, nano-scaled grinding, ultrafine and superfine grinding. The authors highlighted the uses of these types of milling in agro-industrial products such as nutmeg (Myristica fragrans), wheat bran (Triticum spp.), ginger (Zingiber officinale), and green tea powder (Camellia sinensis), among others. CONCLUSION: It is observed that engineering texts dealing with theoretical and analytical food milling operations do not emphasize the new trends found. As a complementary part of this study, eight patents related to cryogenic grinding in food were analyzed, identifying uses of this type of grinding in coffee, lipids, lycopene, proteins, grains, and seeds. Besides, a search was carried out to find out commercial suppliers of cryogenic grinding equipment, in which six companies from China with their equipment were identified.

Asunto(s)

RESUMEN

Resumen: El bruxismo se define como una actividad repetitiva de los músculos masticatorios caracterizada por apretar o rechinar los dientes y/o por golpear y balancear la mandíbula. Es de etiología multifactorial y se considera que existe un bruxismo fisiológico necesario para el desarrollo de la cara de los niños. Estos dos aspectos hacen complicado el diagnóstico que se basa fundamentalmente en un cuestionario a los padres y en el examen clínico del niño. Cuando el desgaste fisiológico no se diferencia a tiempo del desgaste parafuncional, trae consecuencias negativas en el niño que alteran su calidad de vida, necesitando un manejo multidisciplinario adecuado. Considerando que es necesario conocer características fundamentales del bruxismo infantil, el objetivo del presente artículo de revisión es realizar una actualización sobre sus manifestaciones circadianas, clasificaciones, prevalencia, etiología, factores de riesgo, diagnóstico y tratamiento que servirá al odontólogo para una temprana identificación y tratamiento.

Abstract: Bruxism is defined as a repetitive activity of the chewing muscles characterized by clenching or grinding of the teeth and/or by striking and swinging the jaw. It is of multifactorial etiology and it is considered that there is a physiological bruxism necessary for the development of the face of children. These two aspects complicate the diagnosis that is fundamentally based on a questionnaire to the parents and on the clinical examination of the child. When the physiological wear does not differentiate in time from the parafunctional wear, it has negative consequences in the child that alter their quality of life, requiring an adequate multidisciplinary management. Considering that it is necessary to know the fundamental characteristics of bruxism in children and adolescents, the objective of this review article is to update its circadian manifestations, classifications, prevalence, etiology, risk factors, diagnosis and treatment that will serve the dentist for the early identification and treatment.

Asunto(s)

RESUMEN

Objective: To compare the effect of canine guidance or group function on diaphragm activity, heart rate, and oxygen saturation during awake teeth grinding at different body positions. Methods: Fifty healthy participants, 25 with canine guidance and 25 with group function, were included. Bilateral electromyographic (EMG) recordings of the diaphragm (DIA) during awake teeth grinding were performed in standing, seated upright, and right lateral decubitus positions. Simultaneously, heart rate and oxygen saturation were measured. Results: EMG activity of the DIA muscle was similar in the working side and non-working side between participants with canine guidance and group function in the different body positions studied. The heart rate and oxygen saturation showed no significant differences between the two groups. Conclusion: EMG activity of the DIA muscle, the heart rate, and oxygen saturation during teeth grinding are not significantly influenced by the type of laterotrusive occlusal scheme.

Asunto(s)

RESUMEN

Curcuma longa is a rhizome used for the extraction of curcumin, a yellow colorant that only represents 3 wt% of the dried rhizome. To increase the possibility of using the entire rhizome as a food colorant, in the present investigation, the effect of ultra-fine friction grinding (supermasscolloider) to obtain turmeric suspensions was evaluated. To achieve this goal, two distances between the grinding stones or Gap were evaluated (G of -1 and -1.5), and the obtained suspensions were characterized by infrared spectroscopy and through the determination of curcumin content, color, particle size, sedimentation index, serum cloudiness, and microstructure. The results establish that a lower G contributes to an increase in the release of curcumin in the suspension up to 21%, which is related to a greater tendency for yellow coloration, observed in the increase of the * b coordinate of color (from 61.588 to 66.497). Additionally, it was found that a lower G generates smaller particle sizes, which is related to a lower turbidity. PRACTICAL APPLICATION: This research shows that ultra-fine friction grinding (UFFG) has great potential for the development of turmeric suspensions. The results have applications in the food industry sector, because UFFG could be used to produce different types of vegetable suspensions.

Asunto(s)

RESUMEN

The objective of the present study was to compare the effects of corn processing on performance and intestinal parameters of weanling piglets. To accomplish our goal, 42 piglets (21 days-old, 7.18±1.0 kg body weight) were randomly allocated (seven pens/treatment; three pigs/pen) to one of two treatments: ground corn ­ corn ground through a hammer mill with a 1.0-mm screen after being ground by a hammer mill with a 3.0-mm screen, and extruded corn ­ corn was wet extruded after being ground by a hammer mill with a 2.0-mm screen and, after extrusion, it was ground by a hammer mill with a 1.0-mm screen. In both methods, corn from the same batch was used. Results were considered statistically significant when P<0.05 and a tendency when P<0.10. Analyses were performed using the GLIMMIX procedure of SAS. Pigs fed ground or extruded corn diet had similar growth performance. Duodenum and jejunum of pigs fed extruded corn had greater villus height compared with those of pigs fed ground corn. Crypt depth was not influenced by corn processing. Duodenum and jejunum of pigs fed extruded corn had greater villus:crypt ratio compared with those of pigs fed ground corn. In the duodenum, the expression of zonula occludens-1 (ZO-1) was greater, and the expression of Occludin-1 tended to be greater in pigs fed the extruded corn diets. There was no effect of corn processing on ZO-1 and Occludin-1 expression in the jejunum, nor TGF-ß1 expression in duodenum and jejunum. There was no effect of the type of corn processing on colonic total bacteria or Enterobacteriaceae and Lactobacillus abundance. Piglets fed diets with ground corn or extruded corn have similar growth performance. However, piglets fed diets with extruded corn present improved intestinal morphology and tight junction protein expression compared with those fed ground corn.(AU)

Asunto(s)

RESUMEN

Introducción El dolor del pulgar secundario a la artrosis de la articulación trapecio-metacarpiana es una condición común, especialmente en mujeres llegando a causar niveles altos de incapacidad en algunos pacientes. El diagnóstico de rizartrosis se basa en el dolor localizado, la inflamación e inestabilidad en la exploración física además de la valoración radiológica. Existen en la actualidad varias pruebas semiológicas que podemos utilizar en el diagnóstico de la rizartrosis sintomática, una de ellas es la prueba de Grind o molienda, que es considerada el patrón de oro. El presente estudio tiene como objetivo describir y evaluar la prueba de Compresión y flexión del pulgar ideada para el diagnóstico de rizartrosis. Materiales y Métodos Se realizó un estudio de corte transversal en el periodo de enero del 2007 a mayo del 2013, Se evaluaron 230 pacientes que acudieron a consulta con síntomas sugestivos de rizartrosis a quienes se les practico simultáneamente la prueba de Grind y la prueba de compresión y flexión para la confirmación del diagnóstico. Resultados De los 230 pacientes que acudieron a consulta, el 87.8% (202) eran mujeres con una edad promedio de 60 años (32 a 86 años). El 14.8% de los pacientes presentaron una afectación bilateral. El 47.8% tenían comorbilidades presentes entre las que se encuentran síndrome de túnel carpiano en el 67.3%, dedo en gatillo 11.8%, entre otras. El índice de concordancia PABAK entre los dos signos semiológicos fue de 0.948, indicando un nivel de acuerdo excelente entre ambos. El 100% de los pacientes fueron diagnosticados por la prueba de flexión y compresión. Discusión producto de obtener una prueba positiva en la totalidad de los pacientes evaluados con la prueba de compresión y flexión, consideramos puede ser una opción que complemente la pesquisa clínica en el paciente con rizartrosis, es necesario entonces estudios posteriores para validar dicha prueba y poder obtener su sensibilidad y especificidad.

Background Thumb pain secondary to osteoarthritis of the trapezium-metacarpal joint is a common condition, especially in women, and causing high levels of disability in some patients. The diagnosis of rhizarthrosis is based on localised pain, inflammation, and instability on physical examination, in addition to radiographic evaluation. There are currently several semiological tests that can be used in the diagnosis of symptomatic rhizarthrosis, one of which is the Grind or grinding test, which is considered the gold standard. The present study aims to describe and evaluate the thumb compression and flexion test designed for the diagnosis of rhizarthrosis. Methods A cross-sectional study was carried out during the period from January 2007 to May 2013. The study included a total of 230 patients that came to the clinic with symptoms suggestive of rhizarthrosis, and on whom the Grind test, the compression test, and flexion were simultaneously performed to confirm the diagnosis. Results Of the 230 patients who attended the clinic, 87.8% (202) were women with a mean age of 60 years (32 to 86 years). A bilateral involvement was observed in 14.8% of the patients. Just under half (47.8%) currently had co-morbidities that included, among others, carpal tunnel syndrome (67.3%) and trigger finger (11.8%). The prevalence-adjusted and bias-adjusted kappa (PABAK) concordance index between the two semiological signs was 0.948, indicating an excellent level of agreement between both. All (100%) of the patients were diagnosed by the flexion and compression test. Discussion Due to obtaining a positive test in all the patients evaluated with the compression and flexion test, it should be considered as a complementary test in the clinical evaluation of patients with rhizarthrosis. Further studies are necessary to validate this test in order to establish its sensitivity and specificity.

Asunto(s)

RESUMEN

This paper evaluated the feasibility of using residual sugar cane bagasse ash with a high carbon content (as-received SCBA) as raw material to produce a pozzolan after controlled recalcination and grinding. Initially, the as-received SCBA was re-burned using rotary (continuous) and muffle (batch) kilns, both at 600 °C for 1 h. Next, the resulting ash was ground in a closed-circuit ball mill with an air classifier system to obtain a product with 50% passing particle size of approximately 10 µm (SCBA600). SCBA600 was then characterized in terms of oxide composition, loss on ignition, density, specific surface area, and pozzolanic activity. A hydration study was carried out using isothermal calorimetry, thermogravimetric analysis and mercury intrusion porosimetry. Additionally, the performance of SCBA600 in mortars was evaluated by axial compression tests. The combination of recalcination at 600 °C, low-energy ultrafine grinding of the material and classification resulted in pozzolanic SCBA. The results also showed that including SCBA600 in cement mortars reduced total accumulated heat and portlandite content in cement-based pastes, in addition to refining pore structure and significantly increasing compressive strength after 3 days of curing.

RESUMEN

The interest of the scientific community for ultrasound techniques has increased in recent years due to its wide range of applications. A continuous effort of researchers and industries has been made in order to improve and increase the applicability of non-destructive evaluations (NDE). In this context, the monitoring of manufacturing processes, such as the grinding process, arises. This work proposes a novel technique of ultrasound monitoring (chirp-through-transmission) through low-cost piezoelectric diaphragms and digital signal processing. The proposed technique was applied to the monitoring of material removal during the grinding process. The technique is based on changes in ultrasonic waves when propagated through the material under study, with the difference that this technique does not use traditional parameters of ultrasonic techniques but digital signal processing (RMS and Counts). Furthermore, the novelty of the proposed technique is also the use of low-cost piezoelectric diaphragms in the emission and reception of ultrasonic waves, enabling the implementation of a low-cost monitoring system. The results show that the monitoring technique proposed in this work, when used in conjunction with the frequency band selection, is sensitive to the material removal in the grinding process and therefore presents an advance for monitoring the grinding processes.

RESUMEN

Innovative monitoring systems based on sensor signals have emerged in recent years in view of their potential for diagnosing machining process conditions. In this context, preliminary applications of fast-response and low-cost piezoelectric diaphragms (PZT) have recently emerged in the grinding monitoring field. However, there is a lack of application regarding the grinding of ceramic materials. Thus, this work presents an analysis of the feasibility of using the acoustic emission signals obtained through the PZT diaphragm, together with digital signal processing in the time-frequency domain, in the monitoring of the surface quality of ceramic components during the surface grinding process. For comparative purpose, an acoustic emission (AE) sensor, commonly used in industry, was used as a baseline. The results obtained by the PZT diaphragm were similar to the results obtained using the AE sensor. The time-frequency analysis allowed to identify irregularities throughout the monitored process.

Asunto(s)