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Dissolution of polyphenolic compounds from condensed tannins powder from wattle species was carried out using water-glycerol mixtures and sulfuric acid (H2SO4) as a catalyst. The study focused on parameters that can be adjusted to maximize the dissolution. The parameters of the dissolution process (mass of glycerol, mass of tannin powder, temperature and stirring time) were screened using a one factor at a time (OFAT) technique, while the optimum conditions were obtained using response surface methodology (RSM). Effects of the mass of glycerol, mass of tannin powder, temperature, and stirring time used on the percentage of dissolved tannin residue was apparent. The amount of undissolved tannin was used as the direct measurement in this study since there is no established method available to test tannin dissolution in water-glycerol-acid solution. The result from RSM based on 30 experimental sets showed that the lowest undissolved tannin powder value was 10% when 75 grams of tannin powder was mixed with 13.56 grams of glycerol, 86.44 grams of water, and 1.00 grams of sulphuric acid, at 75 °C temperature and 44.13 minutes stirring time.

Angina bullosa hemorrhagica (ABH) is a rare oral disorder characterized by blood-filled bullous lesions in the oral cavity and the oropharynx in the absence of an underlying systemic, haematological or mucocutaneous condition. The presentation of the lesions is acute and located on the lining mucosa, mainly on the soft palate. Often, these lesions are single and rupture easily leaving an ulcerated area. In this study, we present 4 ABH cases in 3 women and 1 man and we discuss the main clinicopathological characteristics. The characteristics of this disorder are important to recognize in order to differentiate the lesions from other oral bullous conditions of the oral cavity such as mucocutaneous disorders or blood coagulation disorders., peer-reviewed

Background: Mucormycosis is a life-threatening invasive fungal infection most commonly observed in immunocompromised patients. Throughout the COVID-19 pandemic, a growing number of Mucorales associated infections, now termed COVID-19 associated mucormycosis (CAM), have been reported. Despite an increase in fatality reports, no cases of rhino-orbital CAM complicated with gangrenous bone necrosis have been described in the literature to date. Case: A 56-year-old male with a recent COVID-19 diagnosis developed rhino-orbital mucormycosis after 22 days of treatment with dexamethasone. Cultures and histopathological assessment of tissue biopsy confirmed the diagnosis. The patient survived after treatment with amphotericin B. Conclusions: Mucormycosis is an invasive fungal infection affecting mostly immunocompromised patients. Along with the COVID-19 pandemic, the inappropriate use of steroids, in addition to concurrent risk factors, such as diabetes, has led to an increase in the occurrence of these devastating mycoses, leading to the development of severe presentations and complications, as observed in many cases. Early diagnosis and prompt treatment are crucial in order to avoid dissemination and fatal outcomes.

A simple synthesis strategy afforded a family of hydrogen-bonded azines and Schiff-bases. Although in dilute solution these dyes are faint light emitters, all exhibit bright luminescence upon aggregation. Changing the peripheral substituents from electron donating to electron withdrawing allows emission fine-tuning in a range from bluish-green to orange-red. The crystal structures of the materials reveal that the restriction of intramolecular rotations is the main mechanism for the aggregation-induced emission enhancement properties.

Heat explosions are sometimes observed during the synthesis of phenol formaldehyde (PF) resin. This scenario can be attributed to the high latent heat that was released and not dissipated leading to the occurrence of a runaway reaction. The synthesis temperature and time played important roles in controlling the heat release, hence preventing the resin from hardening during the synthesis process. This study aims to assess the rheological and viscoelasticity behaviors of the PF resin prepared using paraformaldehyde. The prepared PF resin was designed for laminate applications. The rheological behavior of the PF resin was assessed based on the different molar ratios of phenol to paraformaldehyde (P:F) mixed in the formulation. The molar ratios were set at 1.00:1.25, 1.00:1.50 and 1.00:1.75 of P to F, respectively. The rheological study was focused at specific synthesis temperatures, namely 40, 60, 80 and 100 &deg, C. The synthesis time was observed for 240 min, changes in physical structure and viscosity of the PF resins were noted. It was observed that the viscosity values of the PF resins prepared were directly proportional to the synthesis temperature and the formaldehyde content. The PF resin also exhibited shear thickening behavior for all samples synthesized at 60 &deg, C and above. For all PF resin samples synthesized at 60 &deg, C and above, their viscoelasticity results indicated that the storage modulus (G&prime, ), loss modulus(G&Prime, ) and tan &delta, are proportionally dependent on both the synthesis temperature and the formaldehyde content. Heat explosions were observed during the synthesis of PF resin at the synthesis temperature of 100 &deg, C. This scenario can lead to possible runaway reaction which can also compromise the safety of the operators.

Bio-resins are bio-based materials derived from vegetable resources, especially from vegetable seed oils. It is widely known that bio-resources are renewable, highly available, and sustainable. Resins and most polymers are largely derived from petroleum-based sources that are known to pose chemical risks. Resins have practical applications in printing inks, plasticisers and diluents, as well as in coating materials. Vegetable oils possess a large number of oxirane groups, which are essential for epoxidation to occur, resulting in the production of bio-resins. This undeniably serves as a promising candidate for competing with fossil-fuel-derived petroleum-based products. Thus, the aim of this review paper is to highlight aspects related to the production of bio-resins, including the chemical route of vegetable oil epoxidation process and its influencing factors, the reaction kinetics, bio-resins and the physico-chemical and mechanical properties of bio-resins, along with their applications. The resins industry has seen some remarkable progress towards the commercialisation of several bio-resins originating from vegetable oils, such as soybean oil, castor oil, and linseed oil. This success has undoubtedly intensified further efforts in fields related to bio-resin applications. Research and development is ongoing with the aim of customising a feasible formulation for the synthesis of bio-resins with the desired properties for catering to various applications

Owing to the high cost of synthetic aramid fibers and the necessity for environmentally friendly alternatives, a portion of aramid was replaced by plain woven kenaf fiber, with different lay arrangements and thicknesses. The obtained hybrid composites with aramid and kenaf fibers were used to produce prototypes of army helmet shells. A hybrid composite material was produced using a hot press technique and comprises 19 layers of plain woven kenaf and aramid of various configurations and alternation. The behavior of this composite material on a quasi-static penetration test was studied and was found positive in terms of maximum load carried, energy absorbed in impact, and damage mechanisms. Consequently, a helmet armour was developed that was less costly and more readily available and that which could also be produced by reducing the potential harmful effects of petroleum products, without compromising the ballistic-resistant capability of the material.

Plant oils and their derivatives have been vigorously exploited as alternatives for synthesis of epoxides due to depletion of petroleum resources. In this study, crude jatropha oil (CJO) was subjected to a transesterification process to form jatropha methyl esters (JME) using peroxyacetic acid generated in situ from hydrogen peroxide and acetic acid via an acidic ion exchange resin (AIER). The effect of temperature, molar ratio of hydrogen peroxide to unsaturation, molar ratio of acetic acid to unsaturation, and catalyst loading were investigated. This study revealed that the maximum 89.9% relative conversion to oxirane rings was achieved after 6 h with the optimal reaction conditions of temperature at 70 ˚C, the molar ratio of hydrogen peroxide to unsaturation of 1.5 mol, the molar ratio of acetic acid to unsaturation of 0.5 mol, and catalyst loading of 16%. Fourier Transform Infrared (FTIR) spectra of the epoxidized jatropha methyl esters (EJME) showed oxirane peaks (doublet) at 825 and 843 cm-1.1H NMR confirmed the diepoxide group at 2.85 ppm and 2.98 ppm, while the diepoxide signals of 1C NMR were present at 56.88-57.06 ppm. Production of bio-epoxides from Jatropha methyl esters hence looks promising with favorable physicochemical properties, availability, and versatility.

In this experiment, thermoset cardanol resin was reinforced with short kenaf bast fibers to produce 100% green composites. Different fiber loadings based on weight ratios (0%, 30%, 40%, 50%, and 60%) were fabricated by the hand layup method followed by compression molding. The results indicated that 50UTK (untreated kenaf fibers) displays the highest mechanical properties (91.9% and 43.4% increment for tensile strength and impact strength, respectively) compared with the brittle cardanol polymer and other combinations of composite. This indicates a great load transfer mechanism by kenaf fiber reinforcement due to good fiber/matrix interface shown in scanning electron microscope (SEM) analyses. On the contrary, short kenaf fiber insertion creates a stress concentration spot at the fiber’s end causing slightly lower flexural properties. Besides, high processing temperature has caused damage to the fibers and made further reduction of flexural strength. Therefore, a better load transfer mechanism has been compensated by negative influences of kenaf fiber insertion. In conclusion, 50 wt% of kenaf fiber insertion is found to be the optimum loading for cardanol matrix.

This paper reviews the tensile properties of bamboo fiber reinforced polymer composites (BFRP). Environmentally friendly bamboo fibers have good mechanical properties, which make them suitable replacements for conventional fibers, such as glass and carbon, in composite materials. Better fiber and matrix interaction results in good interfacial adhesion between fiber/matrix and fewer voids in the composite. Several important factors improve matrix-fiber bonding and enhance the tensile properties of BFRP. Coupling agents, such as maleic anhydride polypropylene (MAPP), improve the adhesion of bamboo fibers in the polypropylene (PP) matrix. A high percentage of lignin content in bamboo fibers limits fiber separation, which leads to less matrix absorption between fibers. Steam explosion is the best extraction method for bamboo fibers, although an additional mechanically rubbing process is required for fiber separation. Generally, high fiber content results in good composite performance, but at a certain limit, the matrix does not adhere well with a saturated amount of fibers, and the composite tensile strength decreases. However, the tensile modulus of BFRP is not affected by excess fiber content. Hybridization of bamboo with conventional fibers increases the tensile strength of BFRP. The addition of micro/nano-sized bamboo fibrils into the carbon fabric composites slightly enhances composite strength.

Combat helmets have been utilized to provide protection against a variety of ballistic threats, by reducing traumatic head injuries and fatalities. Nevertheless, head protection from injury is critical to function and for survivability. Soldiers and civilians incur Traumatic Brain Injury (TBI) most commonly from exposure to homemade bombs or improvised explosive devices. Although the Personal Armor System for Ground Troops (PASGT) helmet is expensive, environmental issues are some technical advantages that encourage using natural/synthetic hybrid laminated composites. The effects of different configuration patterns of kenaf fibers on the Backface Signature and energy absorbed by a military helmet (PASGT) were investigated. The ballistic behaviors of the 19 layers of aramid composite and plain woven kenaf composite were compared to hybrid laminated composites. The ballistic impact tests were performed using a 9 mm full metal jacket bullet and fragment simulating projectiles at various impact velocities, using a powder gun on fabricated square panels and helmets. The results showed the positive effect of hybridization in terms of energy absorbed (i.e. penetration), Backface Signature and damage mechanisms for ballistic impact and NIJ (National Institute of Justice) tests. Hybridization of plain woven kenaf/Kevlar laminated composites will open new avenues to reduce the dependency on the ballistic resistance component (Kevlar) in the helmet shell.

The applications of hybrid natural/synthetic reinforced polymer composites have been rapidly gaining market share in structural applications due to their remarkable characteristics and the fact that most of the components made of these materials are subjected to cyclic loading. Their fatigue properties have received a lot of attention because predicting their behavior is a challenge due to the effects of the synergies between the fibers. The purpose of this work is to characterize the tension, compression, and tensile-compression fatigue behavior of six layers of Kevlar hybridized with one layer of woven kenaf reinforced epoxy, at a 35% weight fraction. Fatigue tests were carried out and loaded cyclically at 60%, 70%, 80%, and 90% of their ultimate compressive stress. The results give a complete description for tensile and compression properties and could be used to predict fatigue-induced failure mechanisms.

Kenaf is one of the important plants cultivated for natural fibres globally and is regarded as an industrial crop in Malaysia for various applications. This study was conducted to determine the effects of orientation on the tensile and flexural strengths, Charpy impact test, and morphological properties of kenaf fibre-reinforced poly vinyl butyral (PVB) composites. Laminates of 40% fibre weight fraction were manufactured using the hot press manufacturing technique at 0˚/90˚ and 45˚/−45˚ orientations, and eight specimens were prepared for each test. The mechanical properties of the composites were variably affected by the fibre orientation angle. The results showed that the composites at 0o/90o had the highest tensile strength, flexural strength, and flexural modulus, while the elongation at break was almost the same. Additionally, tests were carried out on the composites to determine their impact energy and impact strength. The results revealed that impact properties were affected in markedly different ways by different orientations. The composite at 45˚/−45˚ offered better impact properties than the composites at 0˚/90˚. In addition, scanning electron microscopy for impact specimens was employed to demonstrate the different failures in the fracture surfaces.

Phenol and formaldehyde are the well-known raw materials used in synthesizing Phenol Formaldehyde (PF) resin. PF resin has been used extensively in various applications including molding and composite laminate industries. This study focused on the synthesizing PF resin using formalin and/or paraformaldehyde for laminate application and assess the physical properties, mechanical properties and fracture toughness of the resins. The density, dynamic viscosity, solid content, gel time, flexural properties, tensile properties and fracture toughness of the synthesized resins were evaluated upon varying the formalin content from 0% to 40% (w/w) in the synthesis process. The result shows that addition of 40% w/w formalin in the PF resin synthesis had increased the fracture toughness and decreased the flexural strength and modulus properties of PF by 97.14% and 97.60% respectively. The tensile stress value was also reduced by 67.80% when the 40% w/w of formalin was added. However, the PF resins that produced by adding formalin up to 20% w/w in the PF resin synthesis, still maintained their flexural and tensile properties within the acceptable range required by EN438 standard for decorative high-pressure laminate (HPL) application. This work shows that paraformaldehyde enhanced the mechanical properties of PF laminate resin compared to formalin.

There is empirical evidence concerning the effectiveness and benefits of game-based learning (GBL). Our mainly interest is to present a tool that can be used to complement teaching software engineering in a motivating and didactic way. . This paper studies the use of a GBL tool called SimulES-W (Simulation in Software Engineering) to teach Software Engineering in an undergraduate engineering program. SimulES-W has three characteristics: it is based on real software cases, it can be customized during the learning process, and it is a collaborative game. These characteristics are important because they help us understand and propose a new learning scenario, and to research with this the learning processes in their environments According to it, the first characteristic of SimulES-W makes it a motivating and engaging game which brings up cases which usually are only present in real software projects. Thanks to the second characteristic, the educators can use SimuelES-W to customize the education material, and tune the game for specific software engineering courses. The third characteristic is related to the proposed game as activity that involves group discussions and decision making. This paper presents SimulES-W a digital version of SimulES and reports the results of an evaluation from a pedagogical perspective, where game adequacy for teaching a subject and positive potential impact in student’s academic performance are investigated.

Noil hemp fiber-reinforced polypropylene composites were fabricated using intermixer and injection molding machines. X-ray microtomography and Weibull statistical methods were employed to characterize the aspect ratio distributions of noil hemp fibers in the polypropylene matrices. The influence of fiber content (0–40 wt%) and compatibilizer addition (5 wt%) on IFSS (interfacial shear strengths) was evaluated by means of the modified Bowyer and Bader model. The evaluated IFSSs decreased from 9.7 to 7.2 MPa as the fiber content increased from 10 to 40 wt%. Also, the outcomes indicated increases to IFSSs for the maleic anhydride grafted polypropylene (MAPP)-coupled composites than uncoupled ones. They were used to predict theoretical tensile strength of the composites. A good agreement has been found between the theoretical and the experimental tensile strengths of composites indicating that the developed model has excellent capability to predict the tensile strength of noil hemp fiber reinforced polypropylene composites. Ultimately, the influences of interfacial shear strength; fiber strength and fiber aspect ratio were investigated using the developed model to predict composite tensile strengths.

We synthesized fused bicyclic polyfunctional compounds containing a highly hydroxylated pyran ring starting from commercially available methyl glucopyranoside and adopting a RCM annulation approach. The versatile α,β-unsaturated ketone group was introduced on the newly formed ring and, as an example of the potential of these polyfunctionalized building blocks, a tetracyclic compound was synthesized through a Diels–Alder cycloaddition reaction.

Xenograft bone has been widely used as a bone grafting material because it gains advantages in biological and mechanical properties as compare with the use of an allograft bone. Heat-treatment of bone is recognized as one of the simple and practical methods to lower the human immunodeficiency virus (HIV) infection and overcome the risks of rejection and disease transfer during the bone transplantation. Therefore, understanding the change of bone’s organic matrix after heat treatment has become a significant topic. In this study, thermal gravimetric analysis (TGA) was used to investigate the condition of organic constituents of a bovine cortical bone. In order to well characterize the microstructural and mechanical property of the bone after heat treatment, nanoindention technique was also employed to measure the localized elastic modulus ( E ) and hardness ( H ) of its interstitial lamellae and osteons lamellae at the temperatures of 23 °C (RT), 37 °C, 90 °C, 120 °C and 160 °C, respectively. The TGA results demonstrated that heat-treated bones had three stages of weight loss. The first stage was the loss of water, which started from RT to 160 °C. Follow by a weight loss of organic constituents starting from 200 °C to 600 °C. Upon reaching 600 °C, the organic constituents were decomposed and mineral phase loss started taking place until 850 °C. From the nanoindentation results, it showed the values of E and H measured for the interstitial lamellae were higher than that of the osteons lamellae. This phenomenon indicates that the interstitial lamellae are stiffer and easy to be mineralized than osteons lamellae. For a specimen heat-treated at 90 °C, the values of E and H of interstitial lamellae and osteons lamellae were similar to a non-heat-treated specimen. For a specimen heat-treated at 120 °C, its interstitial lamellae had higher E and H values than osteons lamellae. When a specimen was heat-treated at 160 °C, both interstitial lamellae and osteons lamellae demonstrated a slight decrease of their E and H values. An ANOVA statistical analysis was used to analyze the difference in elastic properties and hardness in various temperature ranges.

Gomuti is a natural fibre obtained from Arenga pinnata tree. In its native countries, the fibre has been used as roof, rope, insulation and water filter. This paper presents a study into the physical, mechanical and thermal characteristics of gomuti fibre to observe its viability as natural fibre composite material. The study includes observations of fibre morphology, diameter, density, single fibre tensile testing and observation of fibre thermal stability. It was found that diameter of the studied gomuti fibre was in a range of 81–313 µm, with an average of 168 µm. Density of gomuti was ∼1.40 g/cm3. The average strength of single gomuti fibre was 173.9 MPa and the average modulus of elasticity was 3847 MPa. Alkali treatment with sodium hydroxide was conducted to evaluate modifications in the fibre’s characteristics. The treated gomuti fibres show altered diameter range, density, single fibre tensile properties and different thermogravimetric plots. Based on the results, gomuti fibre can be considered viable to be developed into natural fibre composites.

Natural fibres, unlike synthetic fibres fabricated in-house, grow naturally. Their geometrical and physical properties are highly affected by environmental issues such as climate change. For instance, inconsistent cross-sectional areas and shapes along the length of a natural fibre can result from environmental changes. These irregularities in natural fibres affect the ultimate load that can be carried by these fibres in structural engineering applications. In this study, the tensile properties of single hemp fibres were measured by taking into account, the variations in fibre diameters. Alkali, acetyl and silane treatments of fibres were carried out to obtain a better surface finish. The treatment effects on the fibres with respect to tensile properties were discussed. The relationship between tensile properties of treated fibres and the variation of their diameters was also studied. It was found that the tensile strength of chemically-treated fibres was lower than that of untreated fibres.

In this study, hemp fibres were treated with alkali, acetyl and silane chemicals. Fibre constituents such as cellulose, hemicellulose and lignin constituents were separated from treated fibres. The chemical and thermal influences of these constituents on the treated fibres were examined by using scanning electron microscope (SEM), fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Experimental results revealed that, hemicellulose was degraded faster than that of cellulose and lignin. Cellulose exhibited better thermal stability and lignin was degraded in a wide range of temperatures. The hydrophilic nature of the fibres was predominantly caused by the presence of hemicellulose and then lignin constituents. Hemicellulose and lignin were mostly removed by the alkalisation with higher concentrations of NaOH, followed by acetylation. Silane treatment could not remove the hemicellulose and lignin, rather this treatment facilitated coupling with the fibre constituents.

Novel epoxidized hemp oil-based biocomposites containing jute fibre reinforcement were produced at the Centre of Excellence in Engineered Fibre Composites (CEEFC) owing to the need to develop new types of biobased materials. Mechanical properties (tensile, flexural, Charpy impact and interlaminar shear), thermo-mechanical properties (glass transition temperature, storage modulus and crosslink density) and moisture-absorption properties (saturation moisture level and diffusion coefficient) were investigated and compared with samples containing commercially produced epoxidized soybean oil and a synthetic bisphenol A diglycidyl ether-based epoxy control, R246TX cured with a blend of triethylenetetramine and isophorone diamine. Scanning electron microscopy was also performed to investigate the fibre–matrix interface. Epoxidized hemp oil-based samples were found to have marginally superior mechanical, dynamic mechanical and similar water-absorption properties in comparison to samples made with epoxidized soybean oil bioresin; however, both sample types were limited to bioresin concentrations below 30%. Synthetic epoxy-based samples exhibited the highest mechanical, dynamic mechanical and lowest water-absorption properties of all investigated samples. This study has also determined that epoxidized hemp oil-based bioresins when applied to jute fibre-reinforced biocomposites can compete with commercially produced epoxidized soybean oil in biocomposite applications. Fil: Manthey, Nathan W.. University of Southern Queensland; Australia Fil: Cardona, Francisco. University of Southern Queensland; Australia Fil: Francucci, Gaston Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingenieria; Argentina. University of Southern Queensland; Australia Fil: Aravinthan, Thiru. University of Southern Queensland; Australia

Aβ-peptide ligands based on a cis-glycofused benzopyran structure have been fluorescently labeled using coumarine derivatives. Among the synthesized compounds, two conserved their binding ability to β-amyloid peptides, as shown by NMR experiments. Moreover, exploiting its fluorescent property, it was demonstrated that one of such compounds was able to cross an in vitro model of blood–brain barrier (BBB) and to stain Aβ‑deposits.