Dr Suguna Lakshmi M

Three isatin derivatives, namely, 1-allyl-3-hydroxy-3-(6-oxocyclohex-1-en-1-yl)indolin-2-one, C 17 H 17 NO 3 , 1-ethyl-3-hydroxy-3-(6-oxocyclohex-1-en-1-yl)indolin-2-one, C 16 H 17 NO 3 , and 5-bromo-3-hydroxy-1-methyl-3-(6-oxocyclohex-1en-1-yl)indolin-2-one, C 15 H 14 BrNO 3 , were synthesized, crystallized by the slowevaporation technique, characterized by 1 H and 13 C NMR spectroscopy, and analysed by the single-crystal X-ray diffraction (XRD) method. Quantum chemical parameters, such as the energy of the highest occupied molecular orbital, energy of the lowest unoccupied molecular orbital, energy gap, electronic energy, ionization potential, chemical potential, global hardness, global softness and electrophilicity index, were calculated. The druglikeness and bioactivity scores of the compounds were calculated. The activities of these isatin derivatives against bacterial strains, such as Eschericia coli, Proteus vulgaris, Shigella flexneri, Staphylococcus aureus and Micrococcus luteus, and the fungal strain Aspergillus niger, were determined using the well-diffusion assay method. Molecular docking studies were carried out to predict the binding mode of the isatin compounds with the penicillin binding protein enzyme and to identify the interactions between the enzyme and the ligands under study.

Polyurethane nanocomposites were synthesized by using a flame retardant compound containing P and N atoms. Nuclear magnetic resonance spectroscopy confirmed the structure for the prepared triethanolaminodiethyl phosphate (P-OH). Effective construction of polyurethane foam was achieved between P-OH and toluene-2,4-diisocyanate with inclusion of polyethylene glycol (PEG) and polydimethylsiloxane (PDMS). It was then characterized by TGA, DSC, AFM, and XRD. The analyses indicated that the foams were amorphous, but reduced PEG/P-OH (w/w) content changes slightly the microphase separation. An increase in PDMS/PEG ratio in the polyurethane has increased glass transition temperature from 168.3 °C to 177.3 °C. The polyurethane systems were considered as being "slow-burning" with a level of UL-94 V-0, and their ignition delay time was estimated to have eight seconds. This polyurethane system can be used successfully in specific applications for energy-saving measures in buildings.

The leftover vegetable oils after frying of food at higher temperature is toxic to environment as diminutive of technologies for proper disposal and reuse of waste cooking oil. An highly water soluble and emulsifier-free phosphorylated fatliquor with the emulsion stability of more than 60 min from economically cheap deep fried oils on transesterification with highly biodegradable ecologically innocuous and water soluble Poly (ethylene glycol) with p-Toluene Sulphonic acid followed by phosphorylation produces highly water dispersible and stable material for leather applications. The synthesised phosphorylated fatliquors were ascertained for the lubrication of collagen fibres and fibre splitting of goat skin by SEM analysis. The transesterification has confirmed by FT-IR, fat composition oils, COD, BOD, total solid in spent liquor were analysed. Physical characteristics of leathers were analysed by tensile strength, tear strength, elongation and quality assessments by hand evaluation by experts. Acid, iodine, saponification values, particle size of phosphorylated fatliquors, surface wettability, thermal stability of leathers were analysed and the properties compared. The finding can assist an emulsifier-free lubricating process significantly as currently available leather chemicals.

The first discovery of aggregation-induced emission (AIE), whereby luminogen aggregation plays a positive role in enhancing the light-emission efficiency, has piqued the interest of many researchers as it opens up a new avenue for the exploration of practically beneficial luminescent materials. Diverse AIEactive luminogens (or AIEgens) with tunable emission colours and very high quantum yields (up to unity) in the solid state have been extensively utilised in a broad range of fields including optoelectronics, energy and bioscience. In this article, we describe novel fluorene-based fluorogens that exhibit bright emission in the solid-state, mechanical stimuli-responsive optical properties and aggregation-induced emissive ability, and were able to modulate their donor and acceptor properties. The target compounds were synthesized by a Knoevenagel condensation followed by Suzuki cross-coupling reaction, which tends to result in good yields. The target cyanostilbenes (4a-4d) show different reversibly switched states with high contrast through morphology modulation and demonstrate solvatochromic, vapochromic, and AIE properties. These results strongly suggest that compound 4d has better properties than the other derivatives (4a-c) due to the presence of extended donor-acceptor ability. Moreover, density-functional theory (DFT) calculations strongly support the UV-Vis and fluorescence spectral studies. The formation of nano-flakes and cuboid-shaped nanocrystals was further confirmed by FE-SEM and AFM studies. The synthesized compound 4d displayed very bright emission in the solid state and in the aggregate state as compared with the other derivatives (4a-4c). These results might be due to the presence of high-color contrast, which is an advantage for elucidation and overcomes the challenges exhibited in live-cell imaging applications. Moreover, an MTT assay on live A549 cells incubated with the target compound (4d) showed very low cytotoxicity even at high concentrations.

The proposal concerns intentionally added microplastics. It focuses on products which release the plastic particles to the environment directly or via public wastewater treatment plants. These include cosmetic products (e.g. facial scrubs) and household cleaners (e.g. scouring agents), which are rinsed off during or after use and are disposed of down the drain. The rationale behind it is to reduce the release of poorly biodegradable microplastics into the environment because they are absorbed by organisms and can enter the human food chain. The restriction proposal therefore also forms part of the "EU strategy for plastics (2018)". Some Member States have already enacted similar restrictions, and the EU-wide approach is therefore also seeking to achieve harmonisation. The proposal will continue to allow microplastics in products that do not release the particles. However, there will be labelling and reporting requirements on the fate of the plastics. At this point, the ECHA proposal goes beyond the original mandate and the existing regulations of the Member States. It provides for transition periods for certain products. The labelling requirements will apply 18 months, and the reporting obligations 12 months, after the restriction enters into force (for more information: https://echa.europa.eu/de/registry-of-restriction-intentions/-/dislist/details/0b0236e18244cd73).

Fish populations are declining around the world, and many countries are trying to conserve them by regulating their fishing industries. However, controlling fishing locally may not do enough to strengthen fish populations. Often one nation's fish stocks depend on the spawning grounds of a neighboring country, where fish release eggs and sperm into the water and larvae hatch from fertilized eggs. We do research on oceans, climate and fisheries. In a recent study, we showed that global fisheries are even more tightly connected than previously understood. The world's coastal marine fisheries form a single network, thanks to the drift of larvae along ocean currents. This suggests that country-by-country fishery management may be fundamentally insufficient. If a fish species that provides food to one country should decline, the amount of fish spawn, or eggs and larvae, riding the ocean currents from there to other countries would also decline dramatically, resulting in further loss of fish elsewhere.

Microplastics are ubiquitous across ecosystems, yet the exposure risk to humans is unresolved. Focusing on the American diet, we evaluated the number of microplastic particles in commonly consumed foods in relation to their recommended daily intake. The potential for microplastic inhalation and how the source of drinking water may affect microplastic consumption were also explored. Our analysis used 402 data points from 26 studies, which represents over 3600 processed samples. Evaluating

Three-dimensional (3D) cell printing processes have been used widely in various tissue engineering applications due to the efficient embedding of living cells in appropriately designed micro-or macro-structures. However, there are several issues to overcome, such as the limited choice of bioinks and tailor-made fabricating strategies. Here, we suggest a new, innovative cell-printing process, supplemented with a core− sheath nozzle and an aerosol cross-linking method, to obtain multilayered cell-laden mesh structure and a newly considered collagen-based cell-laden bioink. To obtain a mechanically and biologically enhanced cell-laden structure, we used collagen-bioink in the core region, and also used pure alginate in the sheath region to protect the cells in the collagen during the printing and cross-linking process and support the 3D cell-laden mesh structure. To achieve the most appropriate conditions for fabricating cell-embedded cylindrical core−sheath struts, various processing conditions, including weight fractions of the cross-linking agent and pneumatic pressure in the core region, were tested. The fabricated 3D MG63-laden mesh structure showed significantly higher cell viability (92 ± 3%) compared with that (83 ± 4%) of the control, obtained using a general alginate-based cell-printing process. To expand the feasibility to stem cell-embedded structures, we fabricated a cell-laden mesh structure consisting of core (cell-laden collagen)/sheath (pure alginate) using human adipose stem cells (hASCs). Using the selected processing conditions, we could achieve a stable 3D hASC-laden mesh structure. The fabricated cell-laden 3D core−sheath structure exhibited outstanding cell viability (91%) compared to that (83%) of an alginate-based hASC-laden mesh structure (control), and more efficient hepatogenic differentiations (albumin: ∼ 1.7-fold, TDO-2: ∼ 7.6-fold) were observed versus the control. The selection of collagen-bioink and the new printing strategy could lead to an efficient way to achieve 3D cell-laden mesh structures that mimic the anatomical architecture of a patient's defective region.

Alginate hydrogel is a popular biologically inert material that is widely used in 3D bioprinting, especially in extrusion-based printing. However, the printed cells in this hydrogel could not degrade the surrounding alginate gel matrix, causing them to remain in a poorly proliferating and non-differentiating state. Here, we report a novel study of the 3D printing of human corneal epithelial cells (HCECs)/collagen/gelatin/alginate hydrogel incubated with a medium containing sodium citrate to obtain degradation-controllable cell-laden tissue constructs. The 3D-printed hydrogel network with interconnected channels and a macroporous structure was stable and achieved high cell viability (over 90%). By altering the mole ratio of sodium citrate/sodium alginate, the degradation time of the bioprinting constructs can be controlled. Cell proliferation and specific marker protein expression results also revealed that with the help of sodium citrate degradation, the printed HCECs showed a higher proliferation rate and greater cytokeratin 3(CK3) expression, indicating that this newly developed method may help to improve the alginate bioink system for the application of 3D bioprinting in tissue engineering. The technology to fabricate three-dimensional (3D) engineered tissue analogue structures, called 3D printing 1 , would enable researchers and clinicians to tackle the current shortage of tissues and organs needed for transplants and provide platforms for drug testing and studying tissue morphogenesis 2. There are two different approaches using 3D printing technology in tissue engineering 3-9. The first approach is used to create acellular 3D scaffolds and molds, which must be seeded with cells after fabrication 3-6 ; the second approach is used to build tissue constructs by directly depositing cells or cell aggregates, a process known as bioprinting 7-9. A crucial aspect of bioprinting is that the bioink must have printability and biocompatibility because it requires the dispensing of cell-containing media 1,10. The need to operate in an aqueous or aqueous gel environment limits the choice of materials, a situation cited as a significant inhibitor to the growth of bioprinting 11. In extrusion-based printing, hydrogels are solidified through either thermal processes or post-print cross-linking and are used for the printing of cells to produce diverse tissues, ranging from the liver to bone, using materials such as alginate/gelatin chitosan/ gelatin, gelatin/fibrinogen and gelatin methacrylate 12-16. The alginate material system (such as alginate/gelatin) is the most popular material system in use, although it uses biologically inert material that meets the osmolar requirements of the cells, maintains their viability and hardens simply by brief exposure to calcium chloride 17-20. However, there are some concerns over the outcomes of alginate studies. Derby noted that alginate systems are clearly useful for technology development purposes but are unlikely to have any long-term role because of the poor cellular adhesion that has been observed 21. Pati et al. analysed the drawbacks of alginate gels and concluded that cells cannot degrade the surrounding alginate gel matrix; thus, they remain located specifically in their original deposited position during the entire culture period, limiting their capacity to proliferate and differentiate 11. Thus, although there were some successful reports concerning the use of alginate gels to bioprint cell-printed structures, the slow and uncontrollable degradation rates of the bioprinted constructs, which induce minimal cell-proliferation and inferior cell-differentiation, are the foremost concerns. It was already known that, after cross-linking with calcium ions, the slow degradation rate of alginate is due to the low level of released calcium ions 22. Sodium citrate, whose citrate ion can chelate to calcium ions and

Advances in three-dimensional (3D) printing have increased feasibility towards the synthesis of living tissues. Known as 3D bioprinting, this technology involves the precise layer-ing of cells, biologic scaffolds, and growth factors with the goal of creating bioidentical tissue for a variety of uses. Early successes have demonstrated distinct advantages over conventional tissue engineering strategies. Not surprisingly, there are current challenges to address before 3D bioprinting becomes clinically relevant. Here we provide an overview of 3D bioprinting technology and discuss key advances, clinical applications, and current limitations. While 3D bioprinting is a relatively novel tissue engineering strategy, it holds great potential to play a key role in personalized medicine.

Bone is a complex system with functions including those of adaptation and repair. To understand how bone cells can create a structure adapted to the mechanical environment , we propose a simple bone remodeling model based on a reaction-diffusion system influenced by mechanical stress. Two-dimensional bone models were created and subjected to mechanical loads. The conventional finite element method (FEM) was used to calculate stress distribution. A stress-reactive reaction-diffusion model was constructed and used to simulate bone remodeling under mechanical loads. When an external mechanical stress was applied, stimulated bone formation and subsequent activation of bone resorption produced an efficient adaptation of the internal shape of the model bone to a given stress, and demonstrated major structures of trabecular bone seen in the human femoral neck. The degree of adaptation could be controlled by modulating the diffusion constants of hypothetical local factors. We also tried to demonstrate the deformation of bone structure during osteoporosis by the modulation of a parameter affecting the balance between formation and resorption. This simple model gives us an insight into how bone cells can create an architecture adapted to environmental stress, and will serve as a useful tool to understand both physiological and pathological states of bone based on structural information.

Considerable interest has arisen in precision fabrication of cell bearing scaffolds and structures by free form fabrication. Gelatin is an ideal material for creating cell entrapping constructs, yet its application in free form fabrication remains challenging. We demonstrate the use of gelatin, crosslinked with microbial transglutaminase (mTgase), as a material to print cell bearing hydrogels for both 2-dimensional (2-D) precision patterns and 3-dimensional (3-D) constructs. The precision patterning was attained with 3 % gelatin and 2 % high molecular weight poly (ethylene oxide) (PEO) whereas 3-D constructs were obtained using a 5 % gelatin solution. These hydrogels, referred to as Bbioinks^ supported entrapped cell growth, allowing cell spreading and proliferation for both HEK293 cells and Human Umbilical Vein Endothelial Cells (HUVECs). These bioinks were shown to be dispensable by robotic precision, forming patterns and constructs that were insoluble and of suitable stiffness to endure post gelation handling. The two bioinks were further characterized for fabrication parameters and mechanical properties.

Bone remodeling is a process involving removal of mature bone tissue and subsequent formation of new bone tissue. This process is driven by complex actions of biological cells and biochemical factors, and it is sensitive to the loads applied onto the skeleton. Herein, we develop a mathematical framework describing this process at the (macroscopic) level of cortical bone, by combining, for the first time, bone cell population kinetics with multiscale bone mechanics. Key variables are concentrations of biological cells (osteoclasts, osteoblasts and their progenitors) and biochemical factors (RANK, RANKL, OPG, PTH, and TGF-b), as well as mechanical strains, both at the (''macroscopic'') level of cortical bone and at the (''microscopic'') level of the extravascular bone matrix. Multiscale bone mechanics delivers, as a function of the vascular porosity, the relation between the macroscopic strains resulting from the loads, and the microscopic strains, which are known to modulate, either directly, or via poromechanical couplings such as hydrostatic pressure or fluid flow, the expression or proliferation behavior of the biological cells residing in, or attached to the extravascular bone matrix. Hence, these microscopic strains enter the biochemical kinetics laws governing cell expression, proliferation, differentiation, and apoptosis. Without any additional phenomenologically motivated paradigm, this novel approach is able to explain the experimentally observed evolutions of bone mass in postmenopausal osteoporosis and under microgravity conditions: namely, a decrease of bone loss over time.

Implantation of a porous scaffold with a large volume into the body in a convenient and safe manner is still a challenging task in the repair of bone defects. In this study, we present a porous smart nanocomposite scaffold with a combination of shape memory function and controlled delivery of growth factors. The shape memory function enables the scaffold with a large volume to be deformed into its temporal architecture with a small volume using hot-compression and can subsequently recover its original shape upon exposure to body temperature after it is implanted in the body. The scaffold consists of chemically cross-linked poly(ε-caprolactone) (c-PCL) and hydroxyapatite nanoparticles. The highly interconnected pores of the scaffold were obtained using the sugar leaching method. The shape memory porous scaffold loaded with bone morphogenetic protein-2 (BMP-2) was also fabricated by coating the calcium alginate layer and BMP-2 on the surface of the pore wall. Under both in vitro and in vivo environmental conditions, the porous scaffold displays good shape memory recovery from the compressed shape with deformed pores of 33 μm in diameter to recover its porous shape with original pores of 160 μm in diameter. In vitro cytotoxicity based on the MTT test revealed that the scaffold exhibited good cytocompatibility. The in vivo micro-CT and histomorphometry results demonstrated that the porous scaffold could promote new bone generation in the rabbit mandibular bone defect. Thus, our results indicated that this shape memory porous scaffold demonstrated great potential for application in bone regenerative medicine.

Nonwoven and textile membranes have been applied both externally and internally to prescribe boundary conditions for medical conditions as diverse as oedema and tissue defects. Incorporation of mechanical gradients in next generation medical membrane design offers great potential to enhance function in a dynamic, physiological context. Yet the gradient properties and resulting mechanical performance of current membranes are not well described. To bridge this knowledge gap, we tested and compared the mechanical properties of bounding membranes used in both external (compression sleeves for oedema, exercise bands) and internal (surgical membranes) physiological contexts. We showed that anisotropic compression garment textiles, isotropic exercise bands and surgical membranes exhibit similar ranges of resistance to tension under physiologic strains. However, their mechanical gradients and resulting stress-strain relationships show differences in work capacity and energy expenditure. Exercise bands' moduli of elasticity and respective thicknesses allow for controlled, incremental increases in loading to facilitate healing as injured tissues return to normal structure and function. In contrast, the gradients intrinsic to compression sleeve design exhibit gaps in the middle range (1-5 N) of physiological strains and also inconsistencies along the length of the sleeve, resulting in less than optimal performance of these devices. These current shortcomings in compression textile and garment design may be addressed in the future through implementation of novel approaches. For example, patterns, fibre compositions, and fibre anisotropy can be incorporated into biomaterial design to achieve seamless mechanical gradients in structure and resulting dynamic function, which would be particularly useful in physiological contexts. These concepts can be applied further to biomaterial design to deliver pressure gradients during movement of oedematous limbs (compression garments) and facilitate transport of molecules and cells during tissue genesis within tissue defects (surgical membranes). Statement of Significance External and internal biomaterial membranes prescribe boundary conditions for treatment of medical disorders, from oedema to tissue defects. Studies are needed to guide the design of next generation bio-materials and devices that incorporate gradient engineering approaches, which offer great potential to enhance function in a dynamic and physiological context. Mechanical gradients intrinsic to currently implemented biomaterials such as medical textiles and surgical interface membranes are poorly understood. Here we characterise quantitatively the mechanics of textile and nonwoven biomaterial membranes for external and internal use. The lack of seamless gradients in compression medical textiles contrasts with the graded mechanical effects achieved by elastomeric exercise bands, which are designed to deliver controlled, incremental increases in loading to facilitate healing as injured tissues return to normal structure and function. Engineering textiles with a prescient choice of fibre composition/size, type of knit/weave and inlay fibres, and weave density/anisotropy will enable creation of fabrics that can deliver spatially and temporally controlled mechanical gradients to maintain force balances at tissue boundaries , e.g. to treat oedema or tissue defects.

Three-dimensional lattices have applications across a range of fields including structural lightweighting, impact absorption and biomedicine. In this work, lattices based on triply periodic minimal surfaces were produced by polymer additive manufacturing and examined with a combination of experimental and computational methods. This investigation elucidates their deformation mechanisms and provides numerical parameters crucial in establishing relationships between their geometries and mechanical performance. Three types of lattice were examined, with one, known as the primitive lattice, being found to have a relative elastic modulus over twice as large as those of the other two. The deformation process of the primitive lattice was also considerably different from those of the other two, exhibiting strut stretching and buckling, while the gyroid and diamond lattices deformed in a bending dominated manner. Finite element predictions of the stress distributions in the lattices under compressive loading agreed with experimental observations. These results can be used to create better informed lattice designs for a range of mechanical and biomedical applications.

Bone-tendon, bone-ligament and bone-cartilage junctions are multi-tissue interfaces that connect materials that differ by two orders of magnitude in mechanical properties, via gradual variations in mineral content and matrix composition. These sites mediate load transfer between highly dissimilar materials and are consequently a primary site of injury during orthopedic failure. Given the large incidence rate and the lack of suitable surgical solutions for their regeneration or repair, characterization of their natural structure and subsequent replication through tissue engineering is important. Here, we evaluate the ability and accuracy of instrumented indentation to characterize the mechanical properties of both biological tissues and engineered scaffolds with interfaces between materials that contain significant changes in mechanical properties. In this study, finite element simulations and reference samples are developed that characterize how accurately indentation measures the modulus of a material as it varies with distance across a continuous interface between dissimilar tissues with multiple orders of magnitude difference in properties. Finite element simulations accurately predicted discrepancies between the modulus function across an interface observed by indentation and the true modulus function of the material and hence allow us to understand the limits of instrumented indentation as a technique for quantifying gradual changes in material properties. It was found that in order to accurately investigate mechanical property variations in tissues with significant modulus heterogeneity the indenter size should be less than 10 percent of the expected length scale of the modulus variations. Statement of Significance The interfaces between stiff and compliant orthopedic tissues such as bone-tendon, bone-ligament and bone-cartilage are frequent sites of failure during both acute and chronic orthopedic injury and as such their replication via tissue engineering is of importance. The characterization and understanding of these tissue interfaces on a mechanical basis is a key component of elucidating the structure-function relationships that allow them to function naturally and hence a core component of efforts to replicate them. This work uses finite element models and exeperiments to outline the ability of instrumented indentation to characterize the elastic modulus variations across tissue interfaces and provides guidelines for investigators seeking to use this method to understand any interface between dissimilar tissues.

Advancements in the fields of biocompatible materials, manufacturing processes, computational methods and medicine have led to the emergence of a new field: micro-scale scaffolds for bone replacement and regeneration. Yet most such scaffolds produced today are characterized by very basic geometry, and their microstructure differs greatly from that of the actual tissue they are intended to replace. In this paper, we propose a novel approach for generating micro-scale scaffolds based on processing actual micro-CT images and then reconstructing a highly accurate geometrical model. This model is manufactured by means of a state-off f the-art 3D additive manufacturing process from biocompatible materials. At the micro-scale level, these scaffolds are very similar to the original tissue, thus interfacing better with the surrounding tissue and facilitating more efficient rehabilitation for the patient. Moreover, the approach facilitates the design and manufacture of patient-specific scaffolds which can copy patients' exact structural and mechanical characteristics, taking into account their physical condition and medical history. By means of multi-resolution volumetric modeling methods, scaffold porosity can also be adapted according to specific mechanical requirements. The process of designing and manufacturing micro-scale scaffolds involves five major stages: (a) building a volumetric multi-resolution model from micro-CT images; (b) generation of surface geometric model in STL format; (c) additive manufacturing of the scaffold; (d) scaffold shape verification relative to the geometric design; and (e) verification of mechanical properties through finite element analysis. In this research, all the proposed stages of the approach were tested. The input included micro-CT scans of porous ceramic structure, which is quite similar to commercial porous scaffolds. The results show that the proposed method is feasible for design and manufacture of micro-scale scaffolds.

Biomechanical theories to predict bone remodelling have used either mechanical strain or microdamage as the stimulus driving cellular responses. Even though experimental data have implicated both stimuli in bone cell regulation, a mechano-regulatory system incorporating both stimuli has not yet been proposed. In this paper, we test the hypothesis that bone remodelling may be regulated by signals due to both strain and microdamage. Four mechano-regulation algorithms are studied where the stimulus is: strain, damage, combined strain/damage, and either strain or damage with damage-adaptive remodelling prioritised when damage is above a critical level. Each algorithm is implemented with both bone lining cell (surface) sensors and osteocyte cell (internal) sensors. Each algorithm is applied to prediction of a bone multicellular unit (BMU) remodelling on the surface of a bone trabecula. It is predicted that a regulatory system capable of responding to changes in either strain or microdamage but which prioritises removal of damaged bone when damage is above a critical level, is the only one that provides a plausible prediction of BMU behaviour. A mechanism for this may be that, below a certain damage threshold, osteocyte processes can sense changes in strain and fluid flow but above the threshold damage interferes with the signalling mechanism, or causes osteocyte apoptosis so that a remodelling response occurs to remove the dead osteocytes. r

The intercalation of captopril (CP) into the interlayers of montmorillonite (MMT) affords an intestine-selective drug delivery system that has a captopril-loading capacity of up to ca. 14 %w/w and which exhibits near-zero-order release kinetics.

Abstract Appropriate selection of implant biomaterial is a key factor for long-term success of implants. The biologic environment does not accept completely just any material so to optimize biological performance; implants should be selected to reduce the negative biologic response while maintaining adequate function. Prior to developing an implant, a clinician should have sound knowledge about the different biomaterials and its properties. An implant made up of Ti-based alloys provides fruitful performance due to their excellent mechanical, physical, and biological properties. Despite the existence of different types of Ti-based alloys, low modulus β-type Ti-based alloys have superior performance in comparison with other types. Providing good biological fixation through bone tissue in growth into the porous network is the main feature of it. Similar to titanium, the elements belonging to group VI of the Periodic table are found to be suitable for the development of implants. Of which, zirconium has high corrosion resistance and low thermal conductivity. To withstand the longer life of an implant in a biological medium, it possesses high corrosion resistance as well as tissue in growth. The implants made from titanium and zirconium compound yields better solutions. For this modified alloy design, an improvement of strength is expected by combining metal rather than individual metal. Effort has been taken to summarize the various applications of the biomaterials which were used in the past as well in the current world.

The present study focuses on the synthesis of phosphorus-containing epoxy resins, and their use as reactive flame retardants for epoxy. Phosphorus-functionalized epoxy resins were synthesized using different aliphatic diols. Firstly, phosphorus was grafted by reacting phosphoryl chloride with three different aliphatic diols: 1,5-pentanediol, 1,4-butanediol, or 1,3-propanediol. The ensuing phosphorus-triol compounds were then epoxidized with epichlorohydrin in an alkaline medium. Fourier transform infrared and nuclear magnetic resonance spectroscopies confirmed the presence of the epoxy-end group in the structure of synthesized epoxy resins. The phosphorus-containing epoxy resins were mixed with diglycidylether of bisphenol A at a fixed mass ratio of 9:1, and the hybrid formulations were cured with triethylenetetramine as a hardener. Their thermal behaviour was assessed by differential scanning calorimetry and thermogravimetric analysis. Furthermore, the hybrid epoxy resins were blended with nano-clay and applied as a finishing coating on the grain surface of the leather. Thermal analyses of coated leather showed an enhancement of thermal performance with an increase of statistical heat resistant index temperature from 100 to 121 °C. The flame retardation properties were also assessed and found that after coating leather with epoxy nanocomposites, the limiting oxygen index of leather increased from 26.7 ± 0.5% to 28.6 ± 0.7%; meanwhile, ignition time went from 6.0 to 8.1 sec. Consequently, all the coated leather with phosphorus-based epoxy nanocomposites exhibited a self-extinguishing behaviour due to the synergistic effect of P atoms and clay nanoparticles.

The intercalation of captopril (CP) into the interlayers of montmorillonite (MMT) affords an intestine-selective drug delivery system that has a captopril-loading capacity of up to ca. 14 %w/w and which exhibits near-zero-order release kinetics.

Polyurethane nanocomposites were synthesized by using a flame retardant compound containing P and N atoms. Nuclear magnetic resonance spectroscopy confirmed the structure for the prepared triethanolaminodiethyl phosphate (P-OH). Effective construction of polyurethane foam was achieved between P-OH and toluene-2,4-diisocyanate with inclusion of polyethylene glycol (PEG) and polydimethylsiloxane (PDMS). It was then characterized by TGA, DSC, AFM, and XRD. The analyses indicated that the foams were amorphous, but reduced PEG/P-OH (w/w) content changes slightly the microphase separation. An increase in PDMS/PEG ratio in the polyurethane has increased glass transition temperature from 168.3 °C to 177.3 °C. The polyurethane systems were considered as being "slow-burning" with a level of UL-94 V-0, and their ignition delay time was estimated to have eight seconds. This polyurethane system can be used successfully in specific applications for energy-saving measures in buildings.

The leftover vegetable oils after frying of food at higher temperature is toxic to environment as diminutive of technologies for proper disposal and reuse of waste cooking oil. An highly water soluble and emulsifier-free phosphorylated fatliquor with the emulsion stability of more than 60 min from economically cheap deep fried oils on transesterification with highly biodegradable ecologically innocuous and water soluble Poly (ethylene glycol) with p-Toluene Sulphonic acid followed by phosphorylation produces highly water dispersible and stable material for leather applications. The synthesised phosphorylated fatliquors were ascertained for the lubrication of collagen fibres and fibre splitting of goat skin by SEM analysis. The transesterification has confirmed by FT-IR, fat composition oils, COD, BOD, total solid in spent liquor were analysed. Physical characteristics of leathers were analysed by tensile strength, tear strength, elongation and quality assessments by hand evaluation by experts. Acid, iodine, saponification values, particle size of phosphorylated fatliquors, surface wettability, thermal stability of leathers were analysed and the properties compared. The finding can assist an emulsifier-free lubricating process significantly as currently available leather chemicals.

The first discovery of aggregation-induced emission (AIE), whereby luminogen aggregation plays a positive role in enhancing the light-emission efficiency, has piqued the interest of many researchers as it opens up a new avenue for the exploration of practically beneficial luminescent materials. Diverse AIEactive luminogens (or AIEgens) with tunable emission colours and very high quantum yields (up to unity) in the solid state have been extensively utilised in a broad range of fields including optoelectronics, energy and bioscience. In this article, we describe novel fluorene-based fluorogens that exhibit bright emission in the solid-state, mechanical stimuli-responsive optical properties and aggregation-induced emissive ability, and were able to modulate their donor and acceptor properties. The target compounds were synthesized by a Knoevenagel condensation followed by Suzuki cross-coupling reaction, which tends to result in good yields. The target cyanostilbenes (4a-4d) show different reversibly switched states with high contrast through morphology modulation and demonstrate solvatochromic, vapochromic, and AIE properties. These results strongly suggest that compound 4d has better properties than the other derivatives (4a-c) due to the presence of extended donor-acceptor ability. Moreover, density-functional theory (DFT) calculations strongly support the UV-Vis and fluorescence spectral studies. The formation of nano-flakes and cuboid-shaped nanocrystals was further confirmed by FE-SEM and AFM studies. The synthesized compound 4d displayed very bright emission in the solid state and in the aggregate state as compared with the other derivatives (4a-4c). These results might be due to the presence of high-color contrast, which is an advantage for elucidation and overcomes the challenges exhibited in live-cell imaging applications. Moreover, an MTT assay on live A549 cells incubated with the target compound (4d) showed very low cytotoxicity even at high concentrations.

Dicyanate monomer viz bis-4-cyanato-polydimethylsiloxane(PDMS-CY) containing siloxane known as thermally stable structural unit was prepared. The PDMS-CY/DGEBA- Epoxy/Nanoclay were prepared. They were analysed for their properties such as thermal stability, thermal degradation kinetics and microstructures. Keywords: Cyanate ester; Resins; Nanoclay; Nanocomposite; Flame retardance; Degradation kinetics;

New epoxide and cyanate ester resins with an aromatic ester backbone namely 1, 3-[di-(4-glycidyloxy diphenyl-2, 2′-propane)]-isophthalate (DGDPI) and 1, 4-[di-(4-cyanato diphenyl-2, 2′-propane)]-terephthalate (DCDPT) were synthesized and the intermediates were ...

The intercalation of captopril (CP) into the interlayers of montmorillonite (MMT) affords an intestine-selective drug delivery system that has a captopril-loading capacity of up to ca. 14 %w/w and which exhibits near-zero-order release kinetics.

Polyurethane nanocomposites were synthesized by using a flame retardant compound containing P and N atoms. Nuclear magnetic resonance spectroscopy confirmed the structure for the prepared triethanolaminodiethyl phosphate (P-OH). Effective construction of polyurethane foam was achieved between P-OH and toluene-2,4-diisocyanate with inclusion of poly-ethylene glycol (PEG) and polydimethylsiloxane (PDMS). It was then characterized by TGA, DSC, AFM, and XRD. The analyses indicated that the foams were amorphous, but reduced PEG/P-OH (w/w) content changes slightly the microphase separation. An increase in PDMS/PEG ratio in the polyurethane has increased glass transition temperature from 168.3 °C to 177.3 °C. The polyurethane systems were considered as being "slow-burning" with a level of UL-94 V-0, and their ignition delay time was estimated to have eight seconds. This polyurethane system can be used successfully in specific applications for energy-saving measures in buildings.