Advances in Functionally Graded Ceramics – Processing, Sintering Properties and Applications

In multilayered structures, sharp interface is formed between the layers of dissimilar materials. At this interface, the large difference in thermal expansion coefficients of the two dissimilar materials generates residual thermal stresses during subsequent cooling. These stresses lead to cracking at the interface, and these cracks lead to the deterioration of mechanical properties, and finally crack propagation leads to the delamination of the multilayered structure. Scientific progress in the field of material technology, and the continuing developments of modern industries have given rise to the continual demand for ever more advanced materials with the necessary properties and qualities. The need for advanced materials with specific properties has brought about the gradual transformation of materials from their basic states (monolithic) to composites. Recent advances in engineering and the processing of materials have led to a new class of graded multilayered materials called Functionally Graded Materials (FGMs). These materials represent a second generation of composites and have been designed to achieve superior levels of performance. This chapter looks at the best processing technologies and the uses and applications of the advanced, high quality products generated, and also presents an extensive review of the recent novel advances in Functionally Graded Ceramics (FGCs), their processing, properties and applications. The manufacturing techniques involved in this work have involved many concepts from the gradation, consolidation and different sintering processes. Each technique, however, has its own characteristics and disadvantages. In addition, the FGC concept can be applied to almost all material fields. This chapter covers all the existing and potential application fields of FGCs, such as engineering applications in cutting tools, machine parts, and engine components, and discusses properties of FGCs such as heat, wear, and corrosion resistance plus toughness, and their machinability into aerospace and energy applications

A Variable Speed Synchronous Motor Approach for Smart Irrigation using Doubly Fed Induction Motor

Department of Electrical Engineering, College of Engineering, Jazan University, Jizan 45142, Saudi Arabia.Doubly Fed Induction Motor (DFIM) is a popular machine used in variable speed drives, and its ruggedness, reliability and simplicity of speed control make it a suitable candidate for use in smart irrigation systems. This paper studies and evaluates the performance of DFIM at different operating conditions and shows that it can be viewed as a variable speed synchronous motor. The research results reveal that DFIM can be used to control the flow rate of water in irrigation systems, by adjusting the speed of the motor to match the desired flow rate. A mathematical model has been developed to optimize the performance of the DFIM in smart irrigation systems, taking into account the specific conditions of the application. In addition, an experimental setup was built and tested to enhance the theoretical results, which showed good correlation between the theoretical and experimental results. The results of this research demonstrate the potential of using the DFIM in smart irrigation systems to improve the performance and efficiency of irrigation and to provide better control and lower costs

Synthesis, physical properties, and carbon dioxide uptake of new metal-sulfamethoxazole complexes

Considerable research is currently being undertaken to reduce atmospheric CO2 levels, and a promising approach is capturing and storing the gas using adsorbents. In this regard, the synthesis and investigation of the potential use of new materials as CO2 storage media has attracted attention from both industry and academia. Metal-organic frameworks have a range of unique chemical and physical properties with many applications. Reported here is the synthesis of three new sulfamethoxazole-metal complexes and their use as models for investigation of the influence of the metal on their ability to absorb CO2. A new Schiff base was first synthesized, in 89 % yield, from the condensation of sulfamethoxazole and 4-(dimethylamino)benzaldehyde under acidic conditions. The reaction of the Schiff base with metal (nickel, copper, and cobalt) chlorides in ethanol under reflux gave the corresponding sulfamethoxazole-metal complexes in 71–80 % yield. Several experiments were conducted to assess the uptake of CO2 under different conditions. The complexes have low surface areas (1.36–5.82 m2/g) and average pore volume and diameters of 0.008–0.018 cm3/g and 2.17–4.08 nm, respectively. They showed some ability to adsorb CO2 (323 K and 40 bars), and the storage capacity was 11.2–26.1 cm3/gm. The cobalt-containing complex had the highest CO2 storage capability (26.1 cm3/g) due to its relatively high surface area (5.82 m2/g), pore volume (0.018 cm3/g), pore diameter (4.08 nm), and surface roughness (11.6) compared to the nickel and copper complexes

A Research Study in the Synthesis and the Applications of Coumarin Derivatives

Many organic and medicinal chemists are interested in the coumarin compounds because of their potential for use in pharmaceuticals and other industries. Coumarin compounds are a significant class of biologically active chemicals. Here, we outline the steps for producing coumarin derivatives quickly and effectively from commercially accessible substrates via multicomponent condensation processes involving pyrone and benzene derivatives. These substances were examined for their potential anti-tumor effects, including their ability to block carbonic anhydrase, activate the cell apoptosis protein, and coumarin and its derivatives are the primary oral anticoagulants. Candida albicans, Aspergillus fumigatus, and Fusarium solani are three distinct fungus species that are resistant to the antifungal properties of synthetic coumarins. Long known are the coumarins' antibacterial, antifilarial, antiulcerogenic, anti-inflammatory, and antioxidant effects. Coumarin has long been valued as a major raw element in the fragrance sector due to its distinct sweet aroma and stability. When mixed with organic essential oils like lavender, citrus, rosemary, and oak moss, it is used as an odour-enhancer to produce a long-lasting impact. It has been utilized as a bleaching or brightening agent in detergents. Materials such as liquid crystalline, organic/inorganic composites, as well as light harvesting, energy transferring compounds, and electro-optics materials are all employed as a dye in organic photo-redox catalysis and as potent photo-sensitizers reagent. These materials polymerize epoxy-silicones, under near-UV and visible light. Coumarin has also found useful as metal-free sensitizers for solar cells

Dr.

Department of Electrical Engineering, College of Engineering, Jazan University, Jizan 45142, Saudi Arabia

Synthesis and application of levofloxacin–tin complexes as new photostabilizers for polyvinyl chloride

Polyvinyl chloride (PVC) is a synthetic polymer with a wide range of applications with impact on our daily life. It can undergo photodegradation with toxic products that are hazardous to both human health and the environment. In addition, photodegradation shortens the useful lifetime of the material. Elongation of the effective lifespan of PVC is, therefore, a salient area of research. Recently, a lot of attention has been directed toward the design, preparation, and usage of new additives that are capable of reducing the photodecomposition of PVC. This work investigates the synthesis of new levofloxacin-tin complexes and their potential exploitation against the photodecomposition of PVC. Several levofloxacin-tin complexes have been synthesized, in high yields, by a simple procedure and characterized. The potential use of the additives as photostabilizers for PVC has been investigated through the determination of weight loss, molecular weight depression, formation of fragments containing carbonyl and alkene groups, and surface morphology of irradiated PVC films. The results show that the new additives are effective in reducing the photodegradation of PVC. The new levofloxacin-tin complexes act as absorbers of ultraviolet light and quenchers of highly reactive species such as free radicals produced during photodegradation. They are more effective photostabilizers compared with organotin complexes previously reported. The complexes containing aromatic substituents were more effective than those counterparts having aliphatic residues

Tin complexes of 4-(Benzylideneamino)benzenesulfonamide: synthesis, structure elucidation and their efficiency as PVC photostabilizers

Poly(vinyl chloride) (PVC) suffers from photo-oxidation and photodegradation when exposed to harsh conditions. Application of PVC thus relies on the development of ever more efficient photostabilizers. The current research reports the synthesis of new complexes of tin and their assessment as poly(vinyl chloride) photostabilizers. The three new complexes were obtained in high yields from reaction of 4-(benzylideneamino)benzenesulfonamide and tin chlorides. Their structures were elucidated using different tools. The complexes were mixed with poly(vinyl chloride) at a very low concentration and thin films were made from the blends. The effectiveness of the tin complexes as photostabilizers has been established using a variety of methods. The new tin complexes led to a decrease in weight loss, formation of small residues, molecular weight depression, and surface alteration of poly(vinyl chloride) after irradiation. The additives act by absorption of ultraviolet light, removal the active chlorine produced through a dehydrochlorination process, decomposition of peroxides, and coordination with the polymeric chains. The triphenyltin complex showed the greatest stabilizing effect against PVC photodegradation as a result of its high aromaticity

Synthesis of methyldopa–tin complexes and their applicability as photostabilizers for the protection of polyvinyl chloride against photolysis

Polyvinyl chloride (PVC) is a ubiquitous thermoplastic that is produced on an enormous industrial scale to meet growing global demand. PVC has many favorable properties and is used in various applications. However, photodecomposition occurs when harsh conditions, such as high temperatures in the presence of oxygen and moisture, are encountered. Thus, PVC is blended with additives to increase its resistance to deterioration caused by exposure to ultraviolet light. In the current research, five methyldopa–tin complexes were synthesized and characterized. The methyldopa–tin complexes were mixed with PVC at a concentration of 0.5% by weight, and thin films were produced. The capability of the complexes to protect PVC from irradiation was shown by a reduction in the formation of small residues containing alcohols, ketones, and alkenes, as well as in weight loss and in the molecular weight of irradiated polymeric blends. In addition, the use of the new additives significantly reduced the roughness factor of the irradiated films. The additives containing aromatic substituents (phenyl rings) were more effective compared to those comprising aliphatic substituents (butyl and methyl groups). Methyldopa–tin complexes have the ability to absorb radiation, coordinate with polymeric chains, and act as radical, peroxide, and hydrogen chloride scavengers

Modification of polyvinyl chloride by organic molecule for the improvement of its thermal stability

Improving the stability of PVC became a task for many research groups to improve its properties and lower plastic pollution. An invented Schiff base was applied as a heat-resistant agent to alter polyvinyl chloride (PVC) behavior under varying temperatures. The efficacy of the Schiff base-treated PVC films in terms of thermal stability was assessed through weight-loss analysis, Fourier transform infrared (FTIR) spectroscopy, an optical microscope, and atomic force microscopy (AFM). The outcomes demonstrated that incorporating the altered PVC extended the polymer's stability duration, consequently lowering its inclination towards degradation. Furthermore, the Schiff base led to a marked decrease in the presence of PVC's conjugated double bonds, consequently reducing weight loss. The enhancement observed can be credited to the Schiff base's strong ability to neutralize HCl and its effectiveness in protecting unstable chlorine atoms within the polymer chains. These alterations, when combined, resulted in a prolonged delay in thermal degradation and alterations in color, affirming the success of the modification method in improving the thermal stability of PVC

Investigation of the impact of chemical modifications on the photostability of polymethyl methacrylate

For practical application, it is crucial to ensure that polymeric materials are protected against degradation due to aging and ultraviolet (UV) irradiation. A range of advancements in developing novel photostabilizers has been made in the last few years. Another approach is the alteration of polymer structures to enhance their ability to resist photodegradation and photooxidation on exposure to UV light for extended periods in harsh conditions. Polymeric chain modifications have proved to be efficient in increasing the photostability of materials. The current work deals with the surface functionalization of polymethyl methacrylate (PMMA) by incorporating organotin moieties on the polymer backbone. PMMA reacts with ethylenediamine to attach amino groups to the polymer chains. The amino group reacts with 2-hydroxynaphthaldehyde to produce the corresponding Schiff base. Adding trisubstituted (methyl, butyl, and phenyl) tin chloride led to the addition of organometallic residence to the polymeric chains. Thin films of the modified PMMA were made and irradiated with ultraviolet light for long durations to test the effect of chain modification on the photostability of polymeric materials. The effect of the substituent on the tin atom on the photostability of PMMA has been analyzed. Various methods were used for assessment, including infrared spectroscopy, weight loss, surface morphology, and roughness factor. The modified polymers showed increased resistance to photodegradation and had lower roughness factor, weight reduction, surface damages, and small fragments generated compared to the blank PMMA. The polymer containing phenyl substituents showed the most apparent photostabilization effect and the least destructive changes in the PMMA surface on photoirradiation