Commercial Grade Research Articles

Microstructural Evolutions under Ultrasonic Treatment in 304 and 316 Austenitic Stainless Steels: Impact of Stacking Fault Energy

Herein, the influence of ultrasonic treatment (UST) on the microstructure of AISI‐304 and AISI‐316 stainless steels as two common commercial grades with similar properties but different levels of stacking fault energy (SFE) is compared. The softening effect of the ultrasonic wave on the predeformed structure is demonstrated by microhardness measurements, and the relaxation of tensile residual stresses is affirmed through the X‐ray diffraction (XRD) peak shifting. Electron and optical microscopy reveals a significant impact of ultrasound on the reduction of the deformation twins’ fraction. A new mechanism for detwinning under the action of ultrasonic vibration is proposed using electron backscatter diffraction (EBSD) analysis. Reductions of 25% and 34% are detected in dislocation density of the 10% predeformed tensile sample after 300 W UST for the 304SS and 316SS alloys, respectively. The effect of the SFE is discussed, and it turns out that cross‐slip is the main mechanism of dislocation annihilation as a result of UST. Observation of the low‐deformation regions close to the grain boundaries indicates the occurrence of the recrystallization phenomenon during UST. Dislocation annihilation, detwinning, dislocation absorption to grain boundaries, and recrystallization are regarded as the softening and relaxation mechanisms of UST for austenitic stainless steels.

Determining the effect of heat treatment on iron fortified soybean gari blend and its potential bioavailability

Gari is a cassava based food product which lacks most essential nutrients needed to promote good health and growth. An easy-to-adopt strategy widely accepted and used by most low-income household to improve nutritional intake is to blend nutrient dense and nutrient-poor agricultureal produce in a meal. Soybean is used in food blends, as it contributes to caloric source especially supplementary protein. Micronutrient deficiency has been a major challenge in middle and low income countries. The most prominent of micronutrient deficiencies is iron deficiency, which has a potential harmful developmental effect especially on infants, adolescent girls, pregnant women and the elderly. Gari is widely consumed in Ghana and along the West African coast, therefore can be a good medium for food fortification to improve nutrition. The objective of the study was to fortify defatted soybean gari blend with iron and evaluate the effect of heat treatment on anti-nutrient content, estimated iron bioavailability and colour of the products. A known quantity of commercial food grade ferric sodium (FeNa) EDTA was added to cassava mash (with or without commercial food grade defatted soybean flour) before and after processing into gari. The elemental composition, anti-nutritional properties, estimated iron bioavaliability and colour of the product were determined using appropriate analytical methods. Results showed that fortification with iron improved the iron content of the gari samples (with or without defatted soybean flour). Addition of iron to defatted soybean gari blend before heat treatment significantly (p<0.05) decreased the lightness (L*) and yellowness (b*) of the end product. Blending gari with soybean flour elevated its anti-nutrient content; however the estimated molar ratios of anti-nutrients to iron and zinc contents were within acceptable levels as stipulated by USAID and FAO guidelines. Iron fortification of soybean gari blend has huge potential to reduce iron deficiency anaemia and protein-energy malnutrition among gari consumers in Africa.

Novel Protocol for Resole Phenol Formaldehyde Resins Synthesis with Tubular Reactor and Characterization

AbstractA novel strategy has been established, in the laboratory scale, for the generation of the popular thermosetting resin phenol formaldehyde (PF; resole), through a continuous process using a tubular reactor, which is usually developed in the commercial scale through a batch process. A refractive index technique is employed to evaluate the optimum residence time within the tubular reactor to obtain a commercial grade equivalent of PF resin. The unreacted free formaldehyde level has been found to be very low in the resole resin prepared by using the new route. The initial characterization of the resin has been done through Fourier transform infrared spectroscopy and gel permeation chromatography. The cure characteristics of the resin have been analyzed through differential scanning calorimetry. The degradation features of the cured resole are investigated using a thermo gravimetric analyzer and the fractured surfaces are analyzed through scanning electron microscopy. It has been confirmed that the adverse effects of a batch reactor process can be significantly reduced by adopting a continuous resin manufacturing process for PF resin which can be successfully extended to commercialization after optimization.

Evaluation of Different Starches as Gelling Agents for Micropropagation of Potato

Unavailability of clean planting material is a major constraint of potato production in Eritrea. In vitro multiplication is proved to be a reliable solution; however, due to high media cost and initial investment, its use has been limited. The current study was carried out to evaluate the effectiveness of three starches (corn, potato and barley) of both laboratory and commercial grades as agar substitute, for micropropagation of potato. Single nodes of potato were sub-cultured into a fresh modified Murashige and Skoog (MS) medium supplemented with sucrose (3% w/v) and gelled with 50 g/l of six types of starches in addition to 7 g/l of agar as a control. Gelling agents used showed a highly significant difference in all measured parameters. The pH of all starch based media increased by 0.23-1.3 units during the culture time except the control media which decreased by 0.4 units. Similarly EC showed a decreasing trend in all gelling agents. In most of the measured physical parameters such as plant height, root length, fresh weight and dry weight three starch based media namely laboratory grade potato, commercial corn and laboratory corn showed better results compared to the control media. Survival of in vitro plantlets ranged between 85 and 90% after acclimatization. Both laboratory and commercial grade starch based media resulted in cost reduction of 15-22% and 61-66%, respectively. This implies that using both corn and potato starches can be reliable and cost effective gelling agents for micropropagation of potato.

Artificial Neural Network Predictive Modelling of Laser Micro-Grooving for Commercial Pure Titanium (CP Ti) Grade 2

Grooving is the process of making a narrow channel on a surface of flat or cylindrical workpiece. Groove is precisely made to parts used in automotive, biomedical, and electronics industries. In automotive industries, groove plays an important role especially on mechanical parts to precisely locate seal (o-ring) to prevent gas/oil leakage between dynamic mating parts. On the other hand, artificial neural network (ANN) has been widely used in developing predictive models of various manufacturing processes to save huge amount of production time and money for industries. Unfortunately, very limited research has been investigated on micro groove quality employing ANN predictive models. Therefore, this research work presents on how the Artificial Neural Network (ANN) predictive model has been established, optimised and utilised to predict the laser micro-grooving quality of commercial pure titanium grade 2 material. A 3KW CO2 laser cutting machine was employed considering laser power, gas pressure, cutting speed, depth of cut and focal distance as the design parameters for modelling. On the other hand, three significant responses namely groove depth, groove width and groove corner radius were investigated. Experimental results were fed to establish the ANN predictive model, which then its parameters were optimized to gain high level prediction accuracy. The predicted results of ANN model presented the mean absolute percentage error for groove depth, groove width and groove corner radius at about 7.29%, 10.93% and 11.96% respectively. The obtained predictive results were found quite promising with the average of mean absolute percentage error (MAPE) for quality predictions which falls between 10 to 15%, concluding the validity of the developed ANN predictive model.

All-cellulose functional membranes for water treatment: Adsorption of metal ions and catalytic decolorization of dyes

In this study, we present a facile, one-step method for the manufacturing of all-cellulose, layered membranes containing cellulose nanocrystals (CNC), TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated oxidized cellulose nanofibers (TO-CNF), or zwitterionic polymer grafted cellulose nanocrystals (CNC-g-PCysMA) as functional entities in combination with cellulose fibers and commercial grade microfibrillated cellulose. The presence of active sites such as hydroxyl, carbonyl, thioethers, and amines, gave the membranes high adsorption capacities for the metal ions Au (III), Co (II), and Fe (III), as well as the cationic organic dye methylene blue (MB). Furthermore, the membranes served as excellent metal-free catalysts for the decolorization of dyes via hydrogenation. A 3-fold increase of the hydrogenation efficiency for cationic dyes such as rhodamine B (RhB) and methylene blue was obtained in the presence of membranes compared to NaBH4 alone. Water-based processing, the abundance of the component materials, and the multifunctional characteristics of the membranes ensure their potential as excellent candidates for water purification systems.

Analysis of Formaldehyde Scavenger and Its Reaction Products in POM Using Mass Spectrometry

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;To meet the indoor air quality guideline of newly manufactured vehicles in Korea, China, and other countries, low formaldehyde grade POM (Polyoxymethylene) is used for interior parts essentially. In this paper, formaldehyde scavengers from of 2 commercial low formaldehyde grade POM pellets were identified by LC-MS (Liquid chromatograph-Mass spectrometer) as sebacic dihydrazide and dodecanedioic dihydrazide respectively. The reaction products between formaldehyde and formaldehyde scavengers were also detected, which were converted from hydrazide to hydrazone. So, this kind of additive would be gradually consumed by repetitive molding process or exposure to heat according to formaldehyde emission increase. We are expecting to apply this analytical method and result for quality control and benchmark of low formaldehyde grade POM.&lt;/div&gt;&lt;/div&gt;

Prospects for optimizing the drying process of Virginia 202 tobacco leaves

Cultivation and use of Virginia 202 broadleaf skeletal variety for the production of smoking tobacco has broad prospects. Problems of post-harvest processing of large leaves with a massive midrib consist in high energy costs with an artificial drying method or the provision of facilities for long-term natural drying. The aim of the research is to apply physical method of cutting the leaf midrib to intensify drying and to determine the effect of this technique on the quality indicators of raw materials. It has been found that the technique of cutting the midrib on the Virginia 202 variety contributes to a significant optimization of the drying process without reducing the quality of raw materials. The drying time of leaves with the combined method is reduced by 2,8 times, with the natural method – by 2,3 times, and the quality indicators of raw materials improve. Commercial quality is characterized by the yield of 1 commercial grade, for combined drying the yield of 1 grade has increased in comparison with the control sample by 27% and amounted to 86,5%, with natural drying – the increase in yield is 4%. Cutting the midrib increases the fiber yield by 3–5% and contributes to an increase in the volumetric-elastic properties of the fiber, providing an economical consumption of raw materials for the production of smoking articles, the consumption is 676,8–753,8 g/1000 pcs. The gustatory quality improves, raw materials with a cut midrib have optimal values of the ratio of carbohydrate-protein balance in the range of 1,08–1,5, the strength is preserved due to the lower consumption of nicotine during the shorter drying period, in comparison with drying the leaf without cutting the midrib. Cutting the midrib in Virginia 202 is cost effective.

Flotation of Vostok-2 skarn scheelite sulphide ore with modifiers

This paper describes the results of a study that looked at different reagent regimes of flotation of scheelite skarn ores with soda, sodium bicarbonate and sodium sulphide. According to published research data, these regimes of selective recovery scheelite from Skarn ores of Portuguese and Chinese deposits as an alternative to Petrov method. The results of studying the changes of the optical density of water glass in mixing with soda, sodium bicarbonate and sodium hydroxide at different temperatures are presented. Gelation of water glass is observed in a mixture of soda or sodium bicarbonate. The authors were studied the floatability of calcium minerals of scheelite sulphide ore by combined depressants (water glass and sodium sulphide), their dose (0–11.4 kg/t) and proportions (0.7 to 8), as well as the duration of conditioning at the Laboratory of Primorsky Concentrating Plant (PCP). In the course of research, it was established that a high dose of soda and sodium bicarbonate in the scheelite rougher flotation cycle determines a 2- to 6-times higher yield of rough scheelite concentrate with a 1.8-times lower WO3 enrichment ratio. A rise in the water dose to 1.4 kg/t in the rougher flotation cycle led to the recovery of scheelite falling to 30.4–41%, with the WO3 concentrate quality being 22.78–50.5%, corres pondingly. No commercial quality was reached when scheelite concentrate was subjected to heat treatment in a sodium sulphide (43–62 kg/t) and alkaline environment (рН 13) without water glass. Addition of 3.3 kg/t of water glass to sodium sulphide helped raise the quality of scheelite concentrate after three cleaner flotation to 54% WO3 and the recovery of scheelite was 68.4% only. A recovery of more than 82% of commercial grade scheelite concentrate (WO3 &gt; 50%) was reached when running in standard mode using Petrov method of heat treatment. Application of the above processes, which demonstrated high performance in relation to scheelite ores taken from Skarn deposits of Portuguese and Chinese, to samples of Skarn scheelite sulphide ores from Far Eastern deposits, did not prove successful. The authors would like to thank the Research Laboratory of PCP for support with lab studies.

Thermal and Environmentally Induced Degradation Behaviors of Amorphous and Semicrystalline PLAs Through Rheological Analysis

The degradation behaviors of an amorphous and a semicrystalline PLA (i.e., aPLA and cPLA) with similar molecular weights are compared at elevated temperatures and after being treated under various environmental conditions through using small amplitude oscillatory shear rheological experiments. The degradation behaviors are also studied by differential scanning calorimetry and Fourier-transform infrared spectroscopy analysis. Melt thermal degradation analysis shows that the d-lactic acid content does not affect the degradation behavior of PLAs. This is while the increase in temperature beyond 190 °C dramatically, but still similarly, increases the degradation rate of aPLA and cPLA samples. It is also shown that processing of aPLA through a twin-screw extruder at temperatures below 190 °C and at different screw speeds has a negligible effect on its thermal degradation. The degradation of the PLA samples treated under various humidity levels as well as when exposed to different environments such as tap and sea water, regular garden soil and commercial grade microbial fertilizer, is expedited more dramatically around and beyond the glass transition temperature. This is while the cPLA, with around 50% crystallinity, reveals a much less degradation under the aforementioned conditions. This is because the bulk diffusion of water molecules or micro-organisms is harder in cPLA with a compacted crystalline structure. It should, however, be emphasized that the fertilizer degrades the PLA samples much faster and more pronounced than other environments. The tap and sea water exhibits a similar effect on the degradation of PLA samples. Notably, the temperature is the most effective parameter in expediting the degradation rate of PLA, suggesting that the PLA degradation could gradually occur in the environments with extreme warm weather. The increase in humidity also accelerates such degradation.

Effect of Returnable Material in Batch on Hot Tearing Tendency of AlSi9Cu3 Alloy.

The main reason for the use of returnable material, or recycled alloys, is a cost reduction while maintaining the final properties of the casting. The casting resulting quality is directly related to the correct ratio of commercial grade alloy and alloy made by remelting the returnable material in the batch. The casting quality is also affected by the purity of the secondary raw materials used, the shape complexity and the use of the casting itself. The presented article focuses on the effect of increasing the returnable material content in the batch on the hot tearing susceptibility of AlSi9Cu3 alloy. Hot tears are a complex phenomenon that combines metallurgical and thermo-mechanical interactions of the cast metal. Hot tearing susceptibility was evaluated on the basis of quantitative (HTS—hot tearing susceptibility index) and qualitative evaluation. The negative effect of returnable material in the batch was already manifested at a 20% content in the batch. The critical proportion of the returnable alloy in the batch can be stated as 50%. The alloy with a 50% returnable material content manifested insufficient results of the HTS index and qualitative evaluation, which means increased sensitivity to tearing. The negative effect of returnable material and the increased sensitivity were also confirmed in the evaluation of the fracture surface and hot tear profile. The microstructure of alloys with 50% and higher proportion of returnable material was characterized by a higher amount of iron phases (mainly Al5FeSi), whose sharp ends acted as critical regions of hot tearing and subsequent hot tear propagation, which had a major impact on the increase in hot tearing susceptibility.

Structural, morphological and thermal properties of microcrystalline cellulose extracted from coconut husk fiber

In this work, chemically treated microcrystalline cellulose (MCC-C) was extracted from coconut husk fiber. In order to extract hemicellulose, the sieved coconut husk fiber was treated with sodium hydroxide (NaOH) for dewaxing and acidified using sodium chlorite (NaClO2) to extract the residual lignin (bleaching process). The obtained lignin-free cellulose was then treated with potassium hydroxide (KOH). The characterizations used to equate the MCC-C with commercial grade microcrystalline cellulose (MCC) are solubility test, X-ray diffractogram (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The XRD showed that the crystallinity of MCC and MCC-C increased significantly by 80.15% and 71.8% by chemical treatments. TGA found that the active removal of lignin-hemicelluloses and the thermal stability of the material were about 350–500°C and 300–500°C. The morphology of the fiber confirmed that there is an irregular cross-section, non-uniform surface, a large amount of short microfibrils and some impurities on the surface of the coconut husk fiber. The findings showed that microcrystalline cellulose has been successfully extracted from coconut husk fiber and that it can be used further.

Spectrophotometer on-the-go: The development of a 2-in-1 UV–Vis portable Arduino-based spectrophotometer

The spectrophotometer is an important common analytical equipment that measures the concentration of analytes via their absorbance of light at specific wavelengths. However, its cost, lack of portability and requirement of constant power can limit its widespread use and, in some cases, affect the accuracy of its measurements in time-sensitive field tests. Here we describe the development of a portable and low-cost Arduino-based 2-in-1 UV–Vis spectrophotometer built from off-the-shelf electronics and 3D printing. The assembled device has an overall dimension of 105 × 90 × 140 mm and has photodiodes capable of detecting light wavelengths at a range of 190–1100 nm, transmitting the readings to its corresponding SpectBT UV–Vis Pro smartphone Android app via Bluetooth®. The device sensitivity and limit of detection were compared with a commercial research grade spectrophotometer on the quantification of proteins and nucleic acids. The assembled spectrophotometer – ‘APD UV–Vis SpectBT performed better for A595 measurements while retaining comparable performance for A280 UV measurements. Together, these findings support the assembly of portable self-assembled laboratory equipment for greater accessibility and freedom of mobility.

Two-step immobilization of metronidazole prodrug on TEMPO cellulose nanofibrils through thiol-yne click chemistry for in situ controlled release

Nowadays, drug encapsulation and drug release from cellulose nanofibrils systems are intense research topics, and commercial grades of cellulose nanomaterials are currently available. In this work we present an ester-containing prodrug of metronidazole that is covalently bound to cellulose nanofibrils in aqueous suspension through a two-step immobilization procedure involving green chemistry principles. The presence of the drug is confirmed by several characterization tools and methods such as Raman spectroscopy, elemental analysis, Dynamic Nuclear Polarization enhanced NMR. This technique allows enhancing the sensitivity of NMR by several orders of magnitude. It has been used to study cellulose nanofibrils substrates and it appears as the ultimate tool to confirm the covalent nature of the binding through thiol-yne click chemistry. Moreover, the ester function of the immobilized prodrug can be cleaved by specific enzyme activity thus allowing controlled drug release.

Onasemnogene abeparvovec gene therapy for symptomatic infantile-onset spinal muscular atrophy in patients with two copies of SMN2 (STR1VE): an open-label, single-arm, multicentre, phase 3 trial

Spinal muscular atrophy type 1 is a motor neuron disorder resulting in death or the need for permanent ventilation by age 2 years. We aimed to evaluate the safety and efficacy of onasemnogene abeparvovec (previously known as AVXS-101), a gene therapy delivering the survival motor neuron gene (SMN), in symptomatic patients (identified through clinical examination) with infantile-onset spinal muscular atrophy. STR1VE was an open-label, single-arm, single-dose, phase 3 trial done at 12 hospitals and universities in the USA. Eligible patients had to be younger than 6 months and have spinal muscular atrophy with biallelic SMN1 mutations (deletion or point mutations) and one or two copies of SMN2. Patients received a one-time intravenous infusion of onasemnogene abeparvovec (1·1 × 1014 vector genomes per kg) for 30-60 min. During the outpatient follow-up, patients were assessed once per week, beginning at day 7 post-infusion for 4 weeks and then once per month until the end of the study (age 18 months or early termination). Coprimary efficacy outcomes were independent sitting for 30 s or longer (Bayley-III item 26) at the 18 month of age study visit and survival (absence of death or permanent ventilation) at age 14 months. Safety was assessed through evaluation of adverse events, concomitant medication usage, physical examinations, vital sign assessments, cardiac assessments, and laboratory evaluation. Primary efficacy endpoints for the intention-to-treat population were compared with untreated infants aged 6 months or younger (n=23) with spinal muscular atrophy type 1 (biallelic deletion of SMN1 and two copies of SMN2) from the Pediatric Neuromuscular Clinical Research (PNCR) dataset. This trial is registered with ClinicalTrials.gov, NCT03306277 (completed). From Oct 24, 2017, to Nov 12, 2019, 22 patients with spinal muscular atrophy type 1 were eligible and received onasemnogene abeparvovec. 13 (59%, 97·5% CI 36-100) of 22 patients achieved functional independent sitting for 30 s or longer at the 18 month of age study visit (vs 0 of 23 patients in the untreated PNCR cohort; p<0·0001). 20 patients (91%, 79-100]) survived free from permanent ventilation at age 14 months (vs 6 [26%], 8-44; p<0·0001 in the untreated PNCR cohort). All patients who received onasemnogene abeparvovec had at least one adverse event (most common was pyrexia). The most frequently reported serious adverse events were bronchiolitis, pneumonia, respiratory distress, and respiratory syncytial virus bronchiolitis. Three serious adverse events were related or possibly related to the treatment (two patients had elevated hepatic aminotransferases, and one had hydrocephalus). Results from this multicentre trial build on findings from the phase 1 START study by showing safety and efficacy of commercial grade onasemnogene abeparvovec. Onasemnogene abeparvovec showed statistical superiority and clinically meaningful responses when compared with observations from the PNCR natural history cohort. The favourable benefit-risk profile shown in this study supports the use of onasemnogene abeparvovec for treatment of symptomatic patients with genetic or clinical characteristics predictive of infantile-onset spinal muscular atrophy type 1. Novartis Gene Therapies.

Gene therapy for spinal muscular atrophy: hope and caution

In the past decade major advances have been made in the treatment of spinal muscular atrophy, a devastating, progressive motor neuron disease caused by a deficiency in the SMN protein due to a mutation in the SMN1 gene. Several approaches aimed at increasing production of the SMN protein have been developed. The intrathecal antisense oligonucleotide nusinersen and an oral small molecule risdiplam (approved by the US Food and Drug Administration and the European Medicines Agency) target splicing of the paralogous gene SMN2, hence improving the production of the functional SMN protein. Onasemnogene abeparvovec is a one-time AAV-9-based gene transfer therapy, introducing a full copy of the SMN1 gene. Approval was based on data from the START study, 1 Mendell JR Al-Zaidy S Shell R et al. Single-dose gene-replacement therapy for spinal muscular atrophy. N Engl J Med. 2017; 377: 1713-1722 Crossref PubMed Scopus (936) Google Scholar reporting an unprecedented survival rate at 24 month follow-up and unexpected acquisition of motor milestones in 12 patients with infantile-onset spinal muscular atrophy type 1, the most severe type of the disease, which is characterised by a poor prognosis with short life expectancy. Onasemnogene abeparvovec gene therapy for symptomatic infantile-onset spinal muscular atrophy in patients with two copies of SMN2 (STR1VE): an open-label, single-arm, multicentre, phase 3 trialResults from this multicentre trial build on findings from the phase 1 START study by showing safety and efficacy of commercial grade onasemnogene abeparvovec. Onasemnogene abeparvovec showed statistical superiority and clinically meaningful responses when compared with observations from the PNCR natural history cohort. The favourable benefit–risk profile shown in this study supports the use of onasemnogene abeparvovec for treatment of symptomatic patients with genetic or clinical characteristics predictive of infantile-onset spinal muscular atrophy type 1. Full-Text PDF

THE EFFECT OF EXPANDED GRAPHITE ON THE CHARGING TIME OF STEARIC ACID PHASE CHANGE MATERIAL IN A HOT WATER TANK

The present work is to investigate the thermal conductivity of the phase change material (PCM) of stearic acid (SA) by using the supporting material of expanded graphite (EG). The EG is used with the mass ratio of 10%, 15% and 20%. SA is commercial grade and the EG is formed by thermal method using natural graphite powder and crystalline zinc nitrate. The composite materials of (SA/10% EG, SA/15% EG and SA/20% EG) are prepared by direct impregnation method. Thermal conductivity of pure SA and composite PCMs are investigated by laboratory apparatus of heat transfer base unit TD1002. The thermal conductivity of the SA/10%EG composite PCM has been improved to 0.64 W/mK from that of SA (0.28 W/mK) with the percentage enhancement of 129%. To verify the morphology of the materials, scanning electron microscopy (SEM) analysis is utilized. The results show that the EG is formed in multilayers with pores in which stearic acid is well absorbed. The charging characteristics of pure SA, SA/10% EG and SA/15% EG for low temperature latent heat storage (LHS) system are studied experimentally. The system is applied for domestic water heating. The PCM is filled in a 33 mm diameter cylindrical copper tube and placed in hot water storage tank. The water is filled in tank from the top section through the distributor to uniform entry. The phase change phenomena of the PCMs are measured by inserting thermocouples at two layers of PCM tube. The result shows that the melting time decreases with the increasing mass ratio of expanded graphite in composite PCM. Although the melting time of both layers are nearly the same at the experiment of composite PCMs, the lower layer takes longer time than upper layer for pure PCM. The charging time is decreased by 67% for SA/10%EG and 79% for SA/15% EG composite PCM from that value of pure SA.

Blending Ferulic Acid Derivatives and Polylactic Acid into Biobased and Transparent Elastomeric Materials with Shape Memory Properties.

Thanks to its remarkable properties such as sustainability, compostability, biocompatibility, and transparency, poly-l-lactic acid (PLA) would be a suitable replacement for oil-based polymers should it not suffer from low flexibility and poor toughness, restricting its use to rigid plastic by excluding elastomeric applications. Indeed, there are few fully biobased and biodegradable transparent elastomers-PLA-based or not-currently available. In the last decades, many strategies have been investigated to soften PLA and enhance its toughness and elongation at break by using plasticizers, oligomers, or polymers. This work shows how a ferulic acid-derived biobased additive (BDF) blends with a common rigid and brittle commercial grade of polylactic acid to provide a transparent non-covalently cross-linked elastomeric material with shape memory behavior exhibiting an elongation at break of 434% (vs 6% for pristine PLA). Through a structure-activity relationship analysis conducted with BDF analogues and a modeling study, we propose a mechanism based on π-π stacking to account for the elastomeric properties. Blending ferulic acid derivatives with polylactic acid generates a new family of fully sustainable transparent elastomeric materials with functional properties such as shape memory.

Permittivity Estimation of Dielectric Substrate Materials via Enhanced SIW Sensor

An enhanced substrate integrated waveguide (SIW) cavity sensor is proposed and designed in this work operating under sub -6 GHz 5G band suitable for the accurate permittivity estimation of low-loss dielectric materials. The proposed SIW sensor is designed for the fundamental TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><b>101</b></sub> mode at the resonance frequency of 3 GHz. The designed sensor is excited by employing a newly optimized external coupling topology incorporating a transition offset, contrary to the conventional microstrip feed. Due to which, a fully planar SIW sensor is developed for the first time without incorporating any active component, exhibiting a substantially high unloaded quality factor of nearly 515 basically required for the accurate testing of low loss tangents. Besides, the designed sensor is yielding a high sensitivity of 20 MHz (equivalent to 0.67% in terms of normalized sensitivity) desirable for segregating nearly resembling dielectric constants. Several standard dielectric samples are tested for the performance validation revealing that the proposed sensor is efficiently differentiating between Plexiglass ( ε <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> = 2.6) and PVC ( ε <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> = 2.65). Simultaneously, the sensor is accurately determining even the low loss tangent of Teflon (tan δ = 3.2×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> ). The measurement results are in close agreement with the references available in the literature. A thorough comparison with the state of the art literature corroborates the advantages offered by the proposed sensor and hence, its usability. Apart from characterizing the commercial grade dielectrics, this resonator is also potentially appropriate for designing high performance RF filters, oscillators and other devices.

A Comparison of Type A and Type M Hardness Measurements on Commercial Fluorocarbon Grades Conforming to AMS7276

Abstract This note provides a comparison and analysis of durometer hardness Type A and Type M per ASTM D2240-15, Standard Test Method for Rubber Property – Durometer Hardness, measured on various commercial grade fluorocarbons conforming to AMS7276, Aerospace Material Specification for Rubber: Fluorocarbon (FKM) High-Temperature-Fluid Resistant Low Compression Set for Seals in Fuel Systems and Specific Engine Oil Systems. This note addresses the seemingly trivial but actually complex problem of how to translate Type A hardness range requirements measured on disks/buttons/plied platens to Type M hardness range requirements measured on O-rings of various cross sections. It confirms there is no simple correlation between Type A and Type M hardness measurements. It is shown that mapping the current Type A hardness range of 70–80 measured on buttons/disks/plied platens onto Type M hardness measurements made on O-rings will require broadening the Type M permitted range to 75, +11, −3 [72 to 86 or 79+/−7]. A tolerance range broader than the typical +/−5 is not without precedent, since the tolerance range for Type A measurements for conductive shielding gaskets per MIL-DTL-83528, General Specification for Gasketing Material, Conductive, Shielding Gasket, Electronic, Elastomer, EMI/RFI, is also +/−7. The data confirm the literature reports that Type M hardness measurements on O-rings are usually higher than Type A on disks/buttons/plied platens, but the difference decreases as the O-ring cross section increases. Though the permitted Type A hardness range for fluorocarbons conforming to AMS7276 is 70–80, actual commercial production is overwhelmingly at the high end of this range and is not centered on the midpoint of 75. The typical Type A hardness requirement range in industry as well as in AMS7276 is only 10 hardness units, but normal measurement variation consumes 45–60 % of that range; hence, obtaining simple correlations between Type A and Type M measurements is not possible because of inherent measurement variation.