Blocking Properties Research Articles

Polyvinyl alcohol‐based fiber membranes with high strength and ultraviolet shielding properties for enhancing the shelf life of grapes

AbstractCurrently, the rising environmental concerns caused by nonbiodegradable food packaging materials have promoted the research and development of biodegradable alternatives. Polyvinyl alcohol (PVA) was selected as the substrate, and zinc oxide nanoparticles (ZnONPs) and titanium dioxide nanoparticles (TiO2NPs) were blended and modified with PVA, respectively. Based on the electrostatic spinning technology to prepare fiber membranes with high strength and UV blocking properties for grapes preservation. The study indicated that the tensile strength of PVA fiber membranes increased by 243% and 209% when ZnONPs and TiO2NPs were added at 1%, respectively. Under UV radiation, the PVA/ZnO composite membranes exhibited superior UV absorption than the PVA/TiO2 composite membranes. After conducting TG tests, it was found that the addition of ZnONPs decreased the thermal stability of the fiber membranes, while TiO2NPs could improve the thermal stability. Both composite membranes could extend grapes' shelf life, but the PVA/ZnO composite membranes were more effective at maintaining freshness than the PVA/TiO2 composite membranes.

Stabilized municipal solid waste as an alternative to natural sand in paver block construction

A large amount of stabilized municipal solid waste (SMSW) obtained in landfill mining operations constitutes about 60–70% of total mining waste. In this study, attempts were made to use SMSW in paver block construction, a unique solution for unpaved urban surfaces considering its ease of handling and low cost. The mechanical and durability properties of the paver block, along with microstructure and mineralogical analysis, were investigated in which various dosages of SMSW vary from 10–50% by the weight of natural sand. The results of various tests, i.e., compressive, flexural strength, abrasion resistance, water absorption, and analysis of microstructure and mineralogical, revealed that SMSW as a partial replacement of natural sand up to 30% replacement could be satisfactorily used in the paver block construction, especially in the low volume roads. Also, the replacements, 40% and 50%, can be used for footpaths, cycle paths, garden parks, domestic drives, and embankment slopes. The geometrical properties and visual aspects were checked to confirm the production standardization of the paver blocks. All the samples have shown promising results in respect of all dimensions. The statistical analysis exhibited that the SMSW had a significant effect on the compressive and flexural strength of the paver block. Therefore, incorporating SMSW as a natural sand replacement will be a sustainable and economical construction solution for light-traffic roads. It also promotes a ‘Circular economy’ as it recycles the stabilized municipal solid waste.

Machine learning for structure-property mapping of Ising models: Scalability and limitations.

We present a scalable machine learning (ML) framework for predicting intensive properties and particularly classifying phases of Ising models. Scalability and transferability are central to the unprecedented computational efficiency of ML methods. In general, linear-scaling computation can be achieved through the divide-and-conquer approach, and the locality of physical properties is key to partitioning the system into subdomains that can be solved separately. Based on the locality assumption, ML model is developed for the prediction of intensive properties of a finite-size block. Predictions of large-scale systems can then be obtained by averaging results of the ML model from randomly sampled blocks of the system. We show that the applicability of this approach depends on whether the block-size of the ML model is greater than the characteristic length scale of the system. In particular, in the case of phase identification across a critical point, the accuracy of the ML prediction is limited by the diverging correlation length. We obtain an intriguing scaling relation between the prediction accuracy and the ratio of ML block size over the spin-spin correlation length. Implications for practical applications are also discussed. While the two-dimensional Ising model is used to demonstrate the proposed approach, the ML framework can be generalized to other many-body or condensed-matter systems.

Residual mechanical resistance of concrete blocks and laying mortars after high temperatures

AbstractThis paper reports an experimental campaign to evaluate the residual mechanical resistance after high temperatures of two structural masonry components: block and mortar. Residual compressive strength and deformation modulus of four different hollow concrete blocks and two different mortar mixes after heating at high temperatures are investigated. The test method used was the one recommended by RILEM TC 200 for mortars and an adaptation of the same method proposed by Medeiros et al. suitable for the geometry of hollow blocks. Despite the sharp drop in the deformation modulus after heating blocks and mortar, no different behaviours are observed in the deformability of the materials caused by the variables studied. The same cannot be said in relation to the variation of the residual compressive strength of the blocks, which is affected by the variables: initial nominal compressive strength and width of the concrete block. Regarding laying mortars, the results confirmed the small influence of compressive strength on the evolution of residual mechanical strength. The data and analyses reported here on the residual mechanical properties of hollow concrete blocks produced from a concrete mixture of very dry consistency, vibro‐pressed and with normal weight aggregates are relevant, since the data found in the literature generally refer to the wet cast concrete material and in cylindrical bodies.

Indian plate segmentation along the Himalayan arc: A multi-proxy approach

The underthrusting Indian plate beneath the Himalaya is considered to be segmented along its arc which is manifested in terms of variations in the angle of underthrusting of the Indian mantle lithosphere (IML) and its northern limit beneath Tibet. The pre-existing transverse ridges in the Ganga foreland basin have also been related to these segmentation boundaries. These segmentations imply a change in the mechanical properties of adjoining blocks which should manifest in the form of spatial variations in the topography build-up and other related parameters. We have analyzed the normalized river channel steepness index (ksn) for the entire Himalaya in conjunction with the northern extent of the IML, width of the Ganga foreland basin, and Bouguer gravity anomaly of the orogen to identify its possible correlation with the lithospheric segments and their boundaries. The results reveal spatial variability in the ksn along the arc linked to the segmentation of the Indian plate. The study suggests six distinct sectors in the Himalaya, similar to the ones delineated based on correlation between the width of the Ganga foreland basin and disposition of major Himalayan thrusts. Major offsets in the pockets of the high ksn from the arc-parallel distribution are related to the transverse tectonic fabric of the Indian plate in the Ganga-Brahmaputra plains. Integration of these results support mechanically strong Indian lithosphere for the Kashmir-Himachal sector and the eastern part of the Arunachal sector and weakest lithosphere for the central-eastern Nepal sector.

Cellulose nanocrystal/graphene oxide one-dimensional photonic crystal film with excellent UV-blocking and transparency

Achieving excellent ultraviolet (UV) blocking properties and maintaining high light transmittance are highly challenging. In this study, a facile and green polymer-assisted vacuum filtration strategy was used to prepare cellulose nanocrystal (CNC) one-dimensional photonic crystal (1DPhC) films with excellent UV-blocking performance and good transparency. The polymer-assisted self-assembly behaviors of CNC and the hydrogen bonding interaction between CNC, polyethylene glycol (PEG), and graphene oxide (GO) drive the homogeneous distribution and parallel alignment of GO. The UV absorption of GO and high reflection of UV resulting from the chiral nematic structure of CNCs result in excellent UV-blocking and high visible light transmission. Besides, the strong hydrogen bonding interaction among CNC, PEG, and GO endows the films with obviously increased mechanical properties. The UV-blocking and the transparency of the CNC composite films could reach 98.3 % and 60.5 %, respectively. Besides, the strain at break of the composite film reached 1.72 ± 0.11 %, which was 535.94 % of neat CNC films. The CNC composite films present great potential in the field of UV-blocking glass, sensors, anti-counterfeiting measures, radiation protection, and so on.

Retention of Intrinsic Photophysical Properties of Porphyrin Building Blocks in 3D Organic Frameworks through Magic Angle Alignment.

Construction of three-dimensional (3D) frameworks maintaining intrinsic photophysical properties of monomeric building blocks is difficult and challenging due to the existence of various molecular interactions, such as metal-organic and π-π interactions. A 3D hydrogen-bonded organic framework (YSH-1Zn) with permanent porosity was constructed using a porphyrin having six carboxylic acid groups (1Zn). Brunauer-Emmett-Teller surface area measurement indicated that YSH-1Zn has a porous structure with a surface area of 392 m2/g. Single-crystal X-ray diffraction analysis revealed that 1Zn creates a 5-fold interwoven 3D network structure adopting a monoclinic system with a space group of P21/c. Each 1Zn within a single crystal exhibits parallel alignment with a slip-stack angle of 54.6°, in good agreement with the magic angle. Although the center-to-center distance of the nearest zinc atoms in YSH-1Zn is only 5.181 Å, the UV/vis absorption and fluorescence emission of YSH-1Zn are not different from those of 1Zn, indicating the absence of an interaction between excitons. Due to the magic angle alignment of 1Zn, the fluorescence lifetime, decay profiles, and quantum yield remained uniform even in the solid state.

Imidazolopiperazine (IPZ)-Induced Differential Transcriptomic Responses on Plasmodium falciparum Wild-Type and IPZ-Resistant Mutant Parasites.

Imidazolopiperazine (IPZ), KAF156, a close analogue of GNF179, is a promising antimalarial candidate. IPZ is effective against Plasmodium falciparum and Plasmodium vivax clinical malaria in human with transmission blocking property in animal models and effective against liver stage parasites. Despite these excellent drug efficacy properties, in vitro parasites have shown resistance to IPZ. However, the mechanism of action and resistance of IPZ remained not fully understood. Here, we used transcriptomic analysis to elucidate mode of action of IPZs. We report, in wild-type parasites GNF179 treatment down regulated lipase enzymes, two metabolic pathways: the hydrolysis of Phosphoinositol 4,5-bipohosphate (PIP2) that produce diacyglycerol (DAG) and the cytosolic calcium Ca2+ homeostasis which are known to be essential for P. falciparum survival and proliferation, as well for membrane permeability and protein trafficking. Furthermore, in wild-type parasites, GNF179 repressed expression of Acyl CoA Synthetase, export lipase 1 and esterase enzymes. Thus, in wild-type parasites only, GNF179 treatment affected enzymes leading lipid metabolism, transport, and synthesis. Lastly, our data revealed that IPZs did not perturb known IPZ resistance genes markers pfcarl, pfact, and pfugt regulations, which are all instead possibly involved in the drug resistance that disturb membrane transport targeted by IPZ.

Graphene nanoribbon doped PVA nanocomposites for improved UVC blocking and luminescence down‐shifting applications

AbstractGraphene nanoribbon (GNR) is quasi‐one dimensional carbon based nanomaterial, distinct from graphene and less explored nanofiller in optical and optoelectronic applications. Herein flexible poly vinyl alcohol (PVA) nanocomposites of 0, 0.25, 0.5 and 0.75 wt % compositions of GNR were prepared by using solution intercalation technique and characterized by spectroscopic methods to assess their structural and optical characteristics. The characterization of PVA@GNR nanocomposites revealed Vander Waals binding of GNR to PVA chains and also considerable crystallographic changes in PVA matrix upon the incorporation of GNR. The optical investigations showed UV‐visible absorption in the wavelength range of 200–280 and 350–520 nm which enhanced on increase in GNR dopant concentration. The decrease in the optical band gap and Urbach energy was also observed for the nanocomposites with increase in dopant concentrations thereby suggesting the formation of localized states in the forbidden band region. The refractive index, absorption coefficient, extinction coefficient and optical conductivity of PVA nanocomposites showed excellent agreement with the band gap revelations and indicated UVC light blocking properties in the wavelength of 200–280 nm. Further, the GNR incorporated PVA nanocomposites exhibited improved thermal stability, wettability transitions (hydrophilic to near hydrophilic) and excellent luminescent down‐conversion properties with a high Stokes's shift (100 nm) compared to pristine PVA nanocomposites. The study concludes that the proposed PVA@GNR nanocomposites can ideally fit optical and photovoltaic device applications owing to their transparency coupled with UV blocking and luminescence down‐shifting attributes.

Enhanced oxygen blocking properties of HfB2-SiC coating by LaB6-HfB2 synergistic reinforcement

To enhance the oxygen blocking properties of HfB2-SiC coatings at high temperatures, LaB6-HfB2 synergistic reinforcement was used to prepare HfB2-SiC-LaB6 coatings, whose oxidation resistance mechanism as well as the structural evolution at 1700 °C was investigated. After LaB6 modification, part of La diffused into Hf-Si-O glass, forming a more stable Hf-La-Si-O composite glass layer. Refractory La oxides embedded in the glass layer, preventing crack propagation and effectively inhibiting the internal diffusion of oxygen. Compared to HfB2-SiC coating, 5 vol% LaB6 added HfB2-SiC coating exhibited the best oxygen blocking performance, whose oxygen permeability and carbon loss rate reduced by 85.3 % and 74.2 %, respectively. However, when LaB6 was added in excess, the excess La2O3 formed by the oxidation of LaB6 consumed local SiO2 in the glass layer, which disrupted the integrity of the glass layer and increased the diffusion of oxygen.

Construction of carboxymethyl chitosan/PVA/chitin nanowhiskers multicomponent film activated with Cotylelobium lanceolatum phenolics and in situ SeNP for enhanced packaging application

This work focused on the construction of bioactive packaging films based on carboxymethyl chitosan and poly(vinyl alcohol) (CMP) as polymeric matrix and fortified with chitin nanowhiskers, Cotylelobium lanceolatum phenolic extract (CL) and in situ synthesized nano selenium. Extensive morphological, microstructural, physical and mechanical analysis revealed that the nanofillers were well-dispersed and integrated into CMP matrix. Incorporation of the extract and nano selenium produced excellent UV blocking properties without seriously compromising the transparency of the composite (CMP/CNW/CLNS1) film. Moreover, blending of CMP with the filler materials significantly elevated (p < 0.05) the surface hydrophobicity (WCA by 35.4°), water barrier (by 53.86 %), tensile strength (from 29.35 to 33.09 MPa), elongation at break (from 64.28 to 96.48 %), and thermal properties of the resultant CMP/CNW/CLNS1 film, with concomitant reduction in water solubility and swellability. Furthermore, the CMP/CNW/CLNS films exhibited remarkable improvement in antioxidant properties. When used for packaging of peeled fresh garlic cloves, the CMP/CNW/CLNS1 film pouch, not the plain CMP or CMP/CNW film pouches, inhibited weight loss, oxidative browning, and the emergence of black mold on the packaged cloves. The developed CMP/CNW/CLNS1 film demonstrated enhanced capacity to safeguard the quality of packaged food and improved shelf life. Therefore, the present study suggests that incorporation of CNW/CLNS into carboxymethyl chitosan/PVA films is a suitable and facile strategy for the fabrication of films with improved mechanical, physico-chemical and functional properties with great potential for application as a sustainable active packaging material in the food industry.

Zn2SnO4 ternary metal oxide for ultraviolet radiation filter application: a comparative study with TiO2 and ZnO

ABSTRACT Ultraviolet (UV) radiation causes serious health risks. Inorganic metal oxides, such as titanium dioxide (TiO2) and zinc oxide (ZnO), have long been recognized for their effectiveness as UV radiation filters/blockers in sunscreen formulations. TiO2 and ZnO as UV-blocking materials have some limitations and issues such as producing harmful radicals and toxicity, respectively. As a result, there is a growing need to develop efficient and safe UV-blocking materials to overcome these limitations associated with the conventional TiO2 and ZnO materials. Zinc stannate (Zn2SnO4), as a ternary metal oxide, is expected to be a promising candidate due to its optical properties and potential for UV-blocking capability. This study presents a comprehensive investigation into the development and characterization of Zn2SnO4 as a potential alternative UV filter to TiO2 and ZnO. The fundamental characteristics, including structural, optical, and photocatalytic characteristics, as well as cell viability, were investigated for two Zn2SnO4 morphologies: cubic aggregate Zn2SnO4 nanoparticles (ZTO CANP) and Zn2SnO4 nanoparticles (ZTO NP), which were compared with the performance of TiO2 nanoparticles (TiO2 NP) and ZnO nanoparticles (ZnO NP). Interestingly, in addition to their promising UVB and partial UVA blocking properties, ZTO CANP and ZTO NP were found to be relativity photocatalytically inactive materials, which means they produce less free radical species as in the case of TiO2 NP, and they cannot be considered as toxic materials as in the case of ZnO NP. To the best of our knowledge, this is the first direct comparison study examining the performance of Zn2SnO4 ternary metal oxide for its potential use as a UV filter. Further research and optimization need to be conducted on these materials, particularly on ZTO CANP as a promising alternative UV filter.

Self-Assembly of Alkanethiols on an Oxide-Free Surface of a Copper Electrode from Alkaline Solutions under Electrochemical Control

Using voltammetry and chronoamperometry, the formation process and properties of insulating nanofilms of alkanethiols with different chain lengths (butane-, octane-, dodecanethiol) obtained on an oxide-free copper surface were studied. The electrochemical method for modifying the copper surface includes the removal of the oxide layer by its cathodic reduction, the adsorption of a thiol under electrochemical control, followed by studying the properties of the resulting nanofilm by voltammetry in one solution. It is shown that, with this approach, a dense thiol film is formed, with its blocking properties depending on the adsorption potential, the time of contact of the electrode with the thiol-containing solution, the thiol concentration, and the presence of dissolved oxygen in the solution. The introduction of ethanol into an aqueous alkali solution leads to a significant acceleration of the process of self-assembly of dodecanethiol, but greatly inhibits the process of self-assembly of butanethiol. The approach proposed in this work makes it possible to use aerated low-concentration thiol-containing solutions to obtain alkanethiol films on the Cu surface with good blocking properties.

Geminal-Based Strategies for Modeling Large Building Blocks of Organic Electronic Materials.

We elaborate on unconventional electronic structure methods based on geminals and their potential to advance the rapidly developing field of organic photovoltaics (OPVs). Specifically, we focus on the computational advantages of geminal-based methods over standard approaches and identify the critical aspects of OPV development. Examples are reliable and efficient computations of orbital energies, electronic spectra, and van der Waals interactions. Geminal-based models can also be combined with quantum embedding techniques and a quantum information analysis of orbital interactions to gain a fundamental understanding of the electronic structures and properties of realistic OPV building blocks. Furthermore, other organic components present in, for instance, dye-sensitized solar cells (DSSCs) represent another promising scope of application. Finally, we provide numerical examples predicting the properties of a small building block of OPV components and two carbazole-based dyes proposed as possible DSSC sensitizers.

Review on Masonry Hollow Block Walls: Materials and Construction

Concrete hollow blocks are commonly used in building construction, particularly for multi-story buildings, factories, and residential structures. Hollow blocks are more practical because of their lightweight, and the most significant feature is the ease with which they can be ventilated. This paper provides an overview of modern masonry hollow block wall construction, starting with an overview of its applications and benefits. Mortars are typically made from cement and sand; with lime or a plasticizer added to improve workability. To improve economy and productivity, compressive strength, density, masonry hollow block properties, and masonry wall behaviour with the factors to consider for load-bearing and non-load-bearing wall construction were summarised and described, and key reference lists are included.

Preparation of dual-functional packaging films containing green tea essential oil microcapsules for strawberry preservation: Excellent barrier properties and antioxidant activity

In this study, gelatin (GEL)/chitosan (CS)/green tea essential oil microcapsule (GTOM) films were prepared by casting to investigate their physicochemical properties and effectiveness in preserving fresh strawberries. GTOM at a maximum content of 30% (based on the total solid mass of GEL-CS) was also well dispersed in the CS and GEL matrix. The results showed that the incorporation of GTOM imparted excellent blocking properties of the films against UV–visible light (transparency and opacity at 600 nm of 35.47% and 7.47, respectively), decent mechanical properties (tensile strength up to 11.08 MPa), good antioxidant properties (60% scavenging activity against DPPH) and satisfactory safety (96.94%). After 7 d of storage at 25 °C, packed strawberries showed the water loss of GTOM-3 compared to polystyrene preservative films (PPF) was reduced to 31.2%, and the hardness was maintained at 3.01 N, showing excellent freshness retention and effectively reducing the loss of nutritional value of strawberries. In addition, the film exhibited good hydrophobicity and inherent biocompatibility, and these results indicate the remarkable potential of the new film for application, making it a promising high-performance preservation material.

The regulation of mechanical properties and freeze-thaw properties of concrete hollow block with granite waste

ABSTRACT Owing to the generation of waste during mining and processing, granite stone causes great damage to the environment. In this study, the broken granite waste and the stone powder were used as concrete coarse aggregate and “admixture” to make granite waste concrete hollow blocks, which could meet the requirements of compressive strength, durability and economy. The influence of the water-binder ratio, cement dosage, and powder-slag ratio on the compressive strength and freeze-thaw properties of the block were analyzed. Subsequently, the optimal mix ratio was determined based on range analysis. The effect of granite waste on the compressive strength and durability of the blocks was also analyzed. In addition, the economic effects of the granite waste concrete hollow block were analyzed. The results show that granite waste concrete hollow blocks with a water-binder ratio of 0.55, powder slag ratio of 15%, and cement dosages of 340 kg/m3 and 320 kg/m3 can meet the strength requirements of MU10 grade and the requirements of freeze-thaw properties. The strength and frost resistance of the granite concrete hollow blocks were enhanced because the granite powder filled the aggregate gaps. In addition, the price of granite concrete hollow blocks was reduced by approximately 50%. The small hollow block of granite concrete is environmentally friendly and worth promoting.

Tailoring the Nucleation and Crystallization Rate of Polyhydroxybutyrate by Copolymerization.

In the polyester family, the biopolymer with the greatest industrial potential could be poly(3-hydroxybutyrate) (PHB), which can be produced nowadays biologically or chemically. The scarce commercial use of PHB derives from its poor mechanical properties, which can be improved by incorporating a flexible aliphatic polyester with good mechanical performance, such as poly(ε-caprolactone) (PCL), while retaining its biodegradability. This work studies the structural, thermal, and morphological properties of block and random copolymers of PHB and PCL. The presence of a comonomer influences the thermal parameters following nonisothermal crystallization and the kinetics of isothermal crystallization. Specifically, the copolymers exhibit lower melting and crystallization temperatures and present lower overall crystallization kinetics than neat homopolymers. The nucleation rates of the PHB components are greatly enhanced in the copolymers, reducing spherulitic sizes and promoting transparency with respect to neat PHB. However, their spherulitic growth rates are depressed so much that superstructural growth becomes the dominating factor that reduces the overall crystallization kinetics of the PHB component in the copolymers. The block and random copolymers analyzed here also display important differences in the structure, morphology, and crystallization that were examined in detail. Our results show that copolymerization can tailor the thermal properties, morphology (spherulitic size), and crystallization kinetics of PHB, potentially improving the processing, optical, and mechanical properties of PHB.

Epileptic manifestations of autoimmune encephalitis

The development of autoimmune encephalitis (AIE) is due to the formation of intracellular and extracellular neuronal antibodies to various structures of the brain tissue. Their prevalence and morbidity are comparable to infectious ones, and the detection rate has recently been increasing. Acute symptomatic seizures are an important component of the clinical core of AIE and are associated with a heterogeneous group of autoantibodies, which along with the features of the lesion topic causes a signi fi cant clinical variety of seizures. The EEG has ictal and interictal features, and the development of electrographic subclinical seizures is also possible. The basis of the treatment of AIE with epileptic seizures is immunotherapy along with the use of antiepileptic drugs with sodium channel blocking properties.

Production and characteristics of stabilised interlocking mud blocks

This paper presents an ideology over physical and mechanical properties of interlocking and non interlocking stabilised mud blocks. These properties are useful to assess the performance and behaviour of load bearing masonry structures. This paper also compares the results of both non interlocking solid stabilised mud blocks (NSMB) of size 230 X 190 X 100 mm and interlocking solid stabilised mud blocks (ISMB) of sizes 230 X 190 X 80 and 230 X 190 X 70 mm. These blocks are tested for block density, Initial rate of water absorption, water absorption, wet compressive strength, flexural strength and Modulus of Elasticity. From the results obtained it has been found that shape and depth of interlocking has significant effect on properties of blocks. Flexural strength of 20mm (ISMB 20) and 30mm (ISMB 30) depth interlocking solid stabilised mud blocks produced are very much comparable with NSMB. Flexural strength of ISMB’s has been tested in both the directions of interlocking effects of blocks which has given satisfactory results. This test shows that Shape considered for interlocking blocks do bond well with filler materials. Mechanical and physical properties of both ISMB and NSMB have exceeded the minimum requirements of blocks as per codal provisions.