Primjena umjetne neuronske mreže u predviđanju čvrstoće na raslojavanje cementne iverice proizvedene od divovske trske i ostataka od prerade šećerne trske

The present article investigates the microstructure of the cement matrices and the products of cement hydration by means of scanning electron microscopy, Fourier transform infrared spectroscopy and X-Ray diffraction. Then, the internal bonding strength (IB) is measured for the mixtures containing various amounts of nanosilica (NS), reed and bagasse particles. Finally, an Artificial Neural Network (ANN) is trained to reproduce these experimental results. The results show that the hardened cement paste including NS features the highest level of C-S-H. However, it has a lower level of C-S-H polymerization if reed or bagasse particles are applied. A relatively new dense microstructural degree is considered in the cement pastes containing NS, and a lower agglomeration is observed in the samples including reed or bagasse particles with NS. According to the microstructural analysis, the addition of NS to the samples containing reed or bagasse particles increases the unhydrated amount of C2S and C3S in the cement paste due to the decrease in the water needed for fully hydrated cement grains through portlandite (Ca(OH)2), C-S-H and ettringite increase. Besides, it is shown that the ANN prediction model is a useful, reliable and quite effective tool for modeling IB of cement-bonded particleboard (CBPB). It is indicated that the mean absolute percentage errors (MAPE) are 1.98 % and 1.45 % in the prediction of the IB values for the training and testing datasets, respectively. The determination coeffi cients (R2) of the training and testing data sets are 0.972 and 0.997 in the prediction of the bonding strength by ANN, respectively.U radu se opisuje istraživanje mikrostrukture cementnih matrica i proizvoda hidratacije cementa uz pomoć pretražnoga elektronskog mikroskopa, Fourierove transformirane infracrvene spektroskopije i rendgenske difrakcije. Pritom je izmjerena i čvrstoća na raslojavanje (IB) za smjese koje sadržavaju različite količine čestica nanosilike (NS), trske i ostataka od prerade šećerne trske. Na kraju su uz pomoć umjetne neuronske mreže (ANN) reproducirani eksperimentalni podatci. Rezultati su pokazali da otvrdnuta cementna pasta s nanosilikom ima najvišu razinu C-S-H. Međutim, ako se rabe čestice trske ili ostataka od prerade šećerne trske, cementna pasta ima niži stupanj polimerizacije C-S-H. Detaljno je analiziran relativno nov stupanj gustoće mikrostrukture cementne paste koja sadržava nanosiliku, pri čemu su uočene i manje nakupine u uzorcima koji su, osim nanosilike, sadržavali i čestice trske ili ostataka od njezine prerade. Prema analizi mikrostrukture, dodatkom nanosilike uzorcima koji sadržavaju čestice trske ili ostataka od prerade šećerne trske povećava se nehidratizirana količina C2S i C3S u cementnoj pasti zbog smanjenja vode potrebne za potpunu hidratizaciju cementnih zrna putem portlandita (Ca(OH)2) te povećanjem C-S-H i etringita. Osim toga, pokazalo se da je ANN model predviđanja koristan, pouzdan i vrlo učinkovit alat za modeliranje čvrstoće cementne iverice na raslojavanje. Srednja apsolutna pogreška (MAPE) u predviđanju čvrstoće na raslojavanje za eksperimentalne i izmjerene skupove podataka iznosi 1,98 %, odnosno 1,45 %. Koefi cijenti korelacije R2 eksperimentalnih i izmjerenih skupina podataka u predviđanju čvrstoće na raslojavanje uz pomoć ANN modela iznose 0,972 odnosno 0,997

Effect of Cellulosic and Rockwool Fibres on Mechanical strengths and Ballistic Impact of Epoxy-bentonite NanoComposite

Nowadays, research studies about optimal application of natural resources in products manufacturing instead of fossil and non-renewable resources are of utmost and ever growing importance. Cellulosic resources as the future reliance of Green products and also mineral mines as plenty, cheap and available materials, especially in Iran, are appropriate options for various products developing. Then, effects of cellulosic fibers and Rockwool fibers (0.25% and 0.5%) in the absence and presence (0.1% and 0.2%) of nano bentonite on conventional and specific properties of Epoxy composite were evaluated. Tensile strength (47.9 MPa), modulus of rupture (86.3 MPa) and modulus of elasticity (2100 MPa) for the mineral fiber/epoxy composite and bentonite/epoxy nanocomposite were higher than the cellulosic fiber/epoxy composite. However, cellulosic fiber/epoxy composite showed higher energy absorption of the ballistic impact with lesser damage area caused by the impact than rockwool/epoxy composite which provide better protection against the ballistic impact. In the presence of nano bentonite particles into the epoxy resin context, rupture and elasticity moduli and tensile strength were dependent on the type and amounts of the additives with superiority of the mineral fibres/epoxy nanocomposite than the cellulosic fibers ones. In contrast, the composites energy absorption caused by the ballistic impact and its damaged area were more successful and favorable in cellulosic fibers than the mineral ones. Somehow that the highest absorbed energy of ballistic impact (60.7 J) and the least damaged area (10.7 cm2) were achieved by the highest application of cellulosic fibers (0.5%) and nano-bentonite (0.2%)

Valorization of Old Corrugated Container to Dissolving Pulp

As an alternative raw material for various cellulose derivatives, the current research studied the processing of old corrugated container (OCC) in the subsequent stages of homogenization (soda cooking) and purification (bleaching with hypochlorite). The properties were characterized in four different categories including chemical composition or purity, accessibility, reactivity, and structural features. Alkali delignification and a bleaching sequence of HEHEHEA were selected for homogenization and purification of pulp followed by characterization of the pulp properties. The dissolving pulp exhibited the following properties: yield, 78%; cellulose, hemicellulose, and lignin content, 90.5%, 7.76%, and 0.3%, respectively; alpha cellulose, 70%. Pulp reactivity measured with two experiments showed Fock reactivity value of 85.67% as well as iodine sorption value (ISV) of 94.95 g/g; accessibility represented by two tests of water retention (WRV) and alkali retention capacity (ARC) with 6.87 for the first and 6.1% for the latter, degree of polymerization (DP), 913.4; crystallinity index, 76.95%; and brightness, 72.87%. FTIR spectroscopy and Brunauer-Emmet-Teller (BET) isotherms were utilized to examine the modifications of OCC to dissolving pulp. The results indicated that the dissolving pulp produced from OCC as a raw material is suitable for DP applications of cellulose derivatives

Valorization of Old Corrugated Container to Dissolving Pulp

As an alternative raw material for various cellulose derivatives, the current research studied the processing of old corrugated container (OCC) in the subsequent stages of homogenization (soda cooking) and purification (bleaching with hypochlorite). The properties were characterized in four different categories including chemical composition or purity, accessibility, reactivity, and structural features. Alkali delignification and a bleaching sequence of HEHEHEA were selected for homogenization and purification of pulp followed by characterization of the pulp properties. The dissolving pulp exhibited the following properties: yield, 78%; cellulose, hemicellulose, and lignin content, 90.5%, 7.76%, and 0.3%, respectively; alpha cellulose, 70%. Pulp reactivity measured with two experiments showed Fock reactivity value of 85.67% as well as iodine sorption value (ISV) of 94.95 g/g; accessibility represented by two tests of water retention (WRV) and alkali retention capacity (ARC) with 6.87 for the first and 6.1% for the latter, degree of polymerization (DP), 913.4; crystallinity index, 76.95%; and brightness, 72.87%. FTIR spectroscopy and Brunauer-Emmet-Teller (BET) isotherms were utilized to examine the modifications of OCC to dissolving pulp. The results indicated that the dissolving pulp produced from OCC as a raw material is suitable for DP applications of cellulose derivatives

Severe Crimean-Congo haemorrhagic fever presented with massive retroperitoneal haemorrhage that recovered without antiviral treatment.

International audienceCrimean-Congo haemorrhagic fever (CCHF) is a tickborne viral zoonosis with up to 50% mortality in humans caused by CCHF virus belonging to the genus Nairovirus, family Bunyaviridae. The geographical distribution of CCHF cases corresponds closely with the distribution of principle tick vectors that is species of Hyaloma. The disease presents with non-specific febrile symptoms, but progress to a serious haemorrhagic syndrome that, soon after, a full blown multi organ failure may develop with prominent features of liver damage and bleeding diathesis. The authors present a case of a 39-year-old man with severe CCHF with retroperitoneal haemorrhage that recovered without ribavirin administration. The case was confirmed for CCHF by serological and molecular tests

Fabrication of Bio-Nanocomposite Based on HNT-Methionine for Controlled Release of Phenytoin

In this study, a novel promising approach for the fabrication of Halloysite nanotube (HNT) nanocomposites, based on the amino acid named Methionine (Met), was investigated. For this purpose, Met layered on the outer silane functionalized surface of HNT for controlled release of Phenytoin sodium (PHT). The resulting nanocomposite (MNT-g-Met) was characterized by FTIR, XRD, Zeta potential, TGA, TEM and FE-SEM. The FT-IR results showed APTES and Met peaks, which proved the modification of the HNTs. The zeta-potential results showed the interaction between APTES (+53.30) and Met (+38.80) on the HNTs (−30.92). The FE-SEM micrographs have displayed the grafting of Met on the modified HNTs due to the nanotube conversion to a rough and indistinguishable form. The amount of encapsulation efficiency (EE) and loading efficiency (LE) of MNT-g-Met was 74.48% and 37.24%, while pure HNT was 57.5%, and 28.75%, respectively. In-vitro studies showed that HNT had a burst release (70% in 6 h) in phosphate buffer while MNT-g-Met has more controlled release profile (30.05 in 6 h) and it was found to be fitted with the Korsmeyer-Peppas model. Due to the loading efficiency and controlled release profile, the nanocomposite promote a good potential for drug delivery of PHT

The Effect of Nanoclay Type on the Mechanical Properties and Antibacterial Activity of Chitosan/PVA Nanocomposite Films

Nanoclays are a class of nanomaterials extensively used to prepare polymer nanocomposites. In this study, four types of common nanoclays were selected to prepare chitosan–polyvinyl alcohol (CP) nanocomposite films. Montmorillonite cloisite Na+ (MMT), organically modified montmorillonite (OMMT), and bentonite (BNT), as layered aluminosilicates, and halloysite nanotubes (HNT), as a tubular nanoclay, were blended with CP films at concentrations of 1.5, 3 and 4.5%. The nanocomposite films were characterized by FTIR, XRD, SEM/EDX, AFM, tensile strength, and antibacterial tests. SEM/EDX results showed a more uniform distribution of the OMMT and HNT nanoclays in the polymer matrix. AFM images showed a rougher surface for nanocomposite films compared to CP film. Increasing the nanoclay concentration in the films from 1.5 to 4.5% resulted in higher tensile strength for HNT and MMT while the trend was reversed for OMMT and BNT. Among the samples, nanocomposite films composed of OMMT and BNT showed the highest tensile strength at the lowest concentrations (CP-OMMT1.5 99 ± 3.7 MPa, CP-B1.5 81 ± 1.5 MPa). The nanocomposite films prepared from OMMT showed the highest antibacterial activity against E. coli and S. aureus with an inhibition zone of 15 and 19 mm, respectively. The results of this study showed that BNT and OMMT are promising nanoclays for enhancing the mechanical properties and antibacterial activity of hydrophilic polymers. The results of this research can provide new insights into selecting suitable nanoclays for different applications

Optimal Modified Starch Content in UF Resin for Glulam Based on Bonding Strength Using Artificial Neural Network

The purpose of this study was to present an application of the artificial neural network (ANN) that predicts the bonding strength of glulam manufactured from plane tree (Platanus orientalis L.) wood layers adhered with a combination of modified starch adhesive and UF resin. Bonding strength was measured at different weight ratios containing different values of nano-zinc oxide as an additive under different conditions of press temperature and press time. As a part of the research, an experimental design was determined. According to that, the glulam specimens were fabricated, the bonding strength of specimens was measured, and the results were statistically analyzed. Then, a model was developed to predict bonding strength using the artificial neural network (ANN) technique. To describe the results, FTIR and TGA tests were also conducted. The experimental results show that the maximum bonding strength values were obtained when the WR was at the middle level (50%), nano-zinc oxide content was at a maximum (4%), and press temperature and press time were fixed at 200 °C and 22 min, respectively. The ANN results agreed well with the experimental results. It became clear that the prediction errors were in an acceptable range. The results indicate that the developed ANN model could predict the bonding strength well with an acceptable error

Physically Crosslinked Chitosan/PVA Hydrogels Containing Honey and Allantoin with Long-Term Biocompatibility for Skin Wound Repair: An In Vitro and In Vivo Study

Chitosan/PVA hydrogel films crosslinked by the freeze–thaw method and containing honey and allantoin were prepared for application as wound dressing materials. The effects of the freeze–thaw process and the addition of honey and allantoin on the swelling, the gel content and the mechanical properties of the samples were evaluated. The physicochemical properties of the samples, with and without the freeze–thaw process, were compared using FTIR, DSC and XRD. The results showed that the freeze–thaw process can increase the crystallinity and thermal stability of chitosan/PVA films. The freeze–thaw process increased the gel content but did not have a significant effect on the tensile strength. The presence of honey reduced the swelling and the tensile strength of the hydrogels due to hydrogen bonding interactions with PVA and chitosan chains. Long-term cell culture experiments using normal human dermal fibroblast (NHDF) cells showed that the hydrogels maintained their biocompatibility, and the cells showed extended morphology on the surface of the hydrogels for more than 30 days. The presence of honey significantly increased the biocompatibility of the hydrogels. The release of allantoin from the hydrogel was studied and, according to the Korsmeyer–Peppas and Weibull models, the mechanism was mainly diffusional. The results for the antimicrobial activity against E. coli and S. aureus bacteria showed that the allantoin-containing samples had a more remarkable antibacterial activity against S. aureus. According to the wound healing experiments, 98% of the wound area treated by the chitosan/PVA/honey hydrogel was closed, compared to 89% for the control. The results of this study suggest that the freeze–thaw process is a non-toxic crosslinking method for the preparation of chitosan/PVA hydrogels with long term biocompatibility that can be applied for wound healing and skin tissue engineering