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Topic Review
Ni-Base Superalloys
Ni-base superalloys are materials largely used in aero-space and energy production sectors, in particular for manufacturing engine parts (e.g. blades, rotors, turbine disks etc.) of aircrafts and aerospace vehicles and parts of power plants (e.g. extraction of oil and gas, nuclear reactors, etc.). At high temperature they exhibit an exceptional combination of high mechanical strength and excellent corrosion resistance. Ni-base superalloys are considered materials of strategic importance and a lot of metallurgical research has been devoted for optimizing their microstructure and improving mechanical properties so that they can operate at ever higher temperature in conditions of safety and reliability. Ni-base superalloys are strengthened by the precipitation of the ordered γ' phase, L12 Ni3(Al,Ti), crystallographically coherent to the f.c.c. γ matrix and their unique mechanical properties at high temperature result from the great microstructure stability. The volume fraction of γ' phase varies from 25% to 50% in polycrystalline superalloys and reaches about 70% in the most modern single crystal superalloys used for the first stage of aeronautical turbine blades. In order to reduce as much as possible the strain misfit between coherent γ and γ' phases (less than 0.4%) they are designed by an accurate tailoring of the chemical composition and a strict control of the process parameters; the resulting interface energy (20-30 mJ/m2) guarantees an excellent stability of the microstructure at high temperature. Other phases such as carbides, borides, γ'', η, δ, σ, µ and Laves phases may be also present with various effects on the mechanical properties; for instance, the topological closed-packed (TCP) σ, µ and Laves phases are undesirable because reduce the ductility.  In spite of the fact that Ni-base superalloys cost from 3 to 5 times the Fe-base ones, their use is expanding especially in gas turbine components for the production of energy because higher temperature of the thermal cycle guarantees greater efficiency and reduction of polluting emission. The demand of Ni-base superalloys is expected to expand also for the energy production through conventional steam turbine plants for achieving super-critical conditions with a predicted increase of efficiency to ~ 60% and reduction of CO2 to about 0.7 ton/kWatth while current sub-critical power plants have an efficiency of ~ 35% and produce 1.2 ton/kWatth of CO2. Of course, higher operating temperature involves more severe degradation of mechanical properties owing to these factors: (i) microstructure evolution including formation of undesired phases, coalescence of γ' precipitates, degeneration of carbides due to fatigue and creep exposure etc.; ii) the formation of cracks. Three topics of great industrial relevance will be discussed hereinafter: (i) microstructural stability; (ii) manufacturing parts of complex geometry; (iii) welding of superalloys. 
  • 2.0K
  • 16 Feb 2022
Topic Review
Rent Regulation in Portugal
The regulation has a significant impact on tenant–landlord relations and the overall functioning of the private rented sector. Different forms of rent regulation—in relation to rent levels, rent increases, security of tenure, etc.—also affect the quality, the social composition and, ultimately, the size of the private rented sector. Together they affect the character of much urban regeneration and renewal. The introduction in Portugal of more flexible rent regimes that aimed to gradually replace open-ended tenancies with freely negotiated contracts led researchers to classify the country as a free market system. 
  • 2.0K
  • 21 Dec 2023
Topic Review
Natural Coagulants for Pharmaceutical Removal from Wastewater
Pharmaceutical contamination threatens both humans and the environment, and several technologies have been adapted for the removal of pharmaceuticals. The coagulation-flocculation process demonstrates a feasible solution for pharmaceutical removal. However, the chemical coagulation process has its drawbacks, such as excessive and toxic sludge production and high production cost. To overcome these shortcomings, the feasibility of natural-based coagulants, due to their biodegradability, safety, and availability, has been investigated by several researchers.
  • 2.0K
  • 30 Jan 2022
Topic Review
Antibacterial Activity of Silver
The problem of antimicrobial resistance is increasingly present and requires the discovery of new antimicrobial agents. Although the healing features of silver have been recognized since ancient times, silver has not been used due to newly discovered antibiotics. Thanks to technology development, a significant step forward has been made in silver nanoparticles research. Nowadays, silver nanoparticles are a frequent target of researchers to find new and better drugs. Namely, there is a need for silver nanoparticles as alternative antibacterial nanobiotics. Silver nanoparticles (AgNPs), depending on their size and shape, also have different antimicrobial activity. In addition to their apparent antibacterial activity, AgNPs can serve as drug delivery systems and have anti-thrombogenic, anti-platelet, and anti-hypertensive properties. Today they are increasingly used in clinical medicine and dental medicine. This paper presents silver antimicrobial activity and its use in dentistry, cardiology, and dermatology, where it has an extensive range of effects
  • 2.0K
  • 17 Sep 2020
Topic Review
Nano Skin Care Formulations
The term “cosmeceutical” was first mentioned in 1984 by Dr. Albert Kligman (University of Pennsylvania), who used it to describe a new category of products that could be classified as more than just cosmetics or pharmaceuticals. According to Dr. Kligman, a cosmeceutical is “a topical preparation that is sold as a cosmetic but has performance characteristics suggestive of a pharmaceutical effect” and therefore might have a pharmaceutical therapeutic effect, but not essentially a biological therapeutic benefit. Since the discovery of the anti-ageing effects of tretinoin, the use of alpha hydroxy acids as exfoliants and for skin rejuvenation, and the use of vitamin C in topical formulations as an antioxidant, the market for cosmeceuticals has grown exponentially and has taken over the personal care industry. Since the term “cosmeceutical” is not yet well established, it is often used in the cosmetic industry to emphasise the specific mechanism of action of the ingredients included in modern skin care formulations. Despite the confusion about their definition and scope, about 40% of dermatologist prescriptions around the world are cosmeceuticals. Nowadays, the use of nanotechnology to improve the efficacy of APIS is a great success.
  • 2.0K
  • 21 Oct 2021
Topic Review
Bulbous Plants Drimia
Drimia (synonym Urginea) plants are bulbous plants belonging to the family Asparagaceae (formerly the family Hyacinthaceae) and are distinctive, powerful medicinal plants. Just some species are indigenous to South Africa and have been traditionally utilized for centuries to cure various diseases and/or ailments. They have been recognized among the most famous and used medicinal plants in South Africa. Traditionally, the plants are used for various illnesses such as dropsy, respiratory disease, bone and joint complications, skin disorders, epilepsy and cancer. A number of studies have reported biological properties such as antiviral, antibacterial, antioxidant and anti-inflammatory, immunomodulatory, and anticancer activities. Their bulbs are a popular treatment for colds, measles, pneumonia, coughs, fever and headaches. 
  • 2.0K
  • 18 Oct 2021
Topic Review
Solid Acid Catalysts for Hock Cleavage of Hydroperoxides
The oxidation of cumene and following cleavage of cumene hydroperoxide (CHP) with sulfuric acid (Hock rearrangement) is still, by far, the dominant synthetic route to produce phenol. In 2020, the global phenol market reached a value of 23.3 billion US$ with a projected compound annual growth rate of 3.4% for 2020–2025. From ecological and economical viewpoints, the key step of this process is the cleavage of CHP. One sought-after way to likewise reduce energy consumption and waste production of the process is to substitute sulfuric acid with heterogeneous catalysts. Different types of zeolites, silicon-based clays, heteropoly acids, and ion exchange resins have been investigated and tested in various studies. For every type of these solid acid catalysts, several materials were found that show high yield and selectivity to phenol.
  • 2.0K
  • 19 Jan 2022
Topic Review
Three-Dimensional In Vitro Cell Culture Models
Despite tremendous advancements in technologies and resources, drug discovery still remains a tedious and expensive process. Though most cells are cultured using 2D monolayer cultures, due to lack of specificity, biochemical incompatibility, and cell-to-cell/matrix communications, they often lag behind in the race of modern drug discovery. There exists compelling evidence that 3D cell culture models are quite promising and advantageous in mimicking in vivo conditions. It is anticipated that these 3D cell culture methods will bridge the translation of data from 2D cell culture to animal models. Although 3D technologies have been adopted widely these days, they still have certain challenges associated with them, such as the maintenance of a micro-tissue environment similar to in vivo models and a lack of reproducibility. However, newer 3D cell culture models are able to bypass these issues to a maximum extent.
  • 2.0K
  • 10 Aug 2022
Topic Review
Crystal Mush
A crystal mush is a magmatic body which contains a significant amount of crystals (up to 50% of the volume) suspended in the liquid phase (melt). As the crystal fraction makes up less than half of the volume, there is no rigid large-scale three-dimensional network as in solids. As such, their rheological behavior mirrors that of absolute liquids. Within a single crystal mush, there is grading to a higher solid fraction towards the margins of the pluton while the liquid fraction increases towards the uppermost portions, forming a liquid lens at the top. Furthermore, depending on depth of placement crystal mushes are likely to contain a larger portion of crystals at greater depth in the crust than at shallower depth, as melting occurs from the adiabatic decompression of the magma as it rises, this is particularly the case for mid-oceanic ridges. Seismic investigation offers strong evidence for the existence of crystal mushes rather than fully liquid magmatic bodies. Crystal mushes can have a wide range of chemical and mineralogical compositions, from mafic (SiO2-poor, MgO-rich) to felsic (SiO2-rich, MgO-poor).
  • 2.0K
  • 01 Dec 2022
Topic Review
Dopamine and Related Drugs as Anti-Inflammatories and Antioxidants
Dopamine (DA), its derivatives, and dopaminergic drugs are compounds widely used in the management of diseases related to the nervous system. However, DA receptors have been identified in nonneuronal tissues, which has been related to their therapeutic potential in pathologies such as sepsis or septic shock, blood pressure, renal failure, diabetes, and obesity, among others. In addition, DA and dopaminergic drugs have shown anti-inflammatory and antioxidant properties in different kinds of cells. 
  • 2.0K
  • 21 Jun 2023
Topic Review
Dam Siting
Dam siting is the study of site selection, a branch of decision making, which has the characteristics of multidisciplinary integration, involving decision making, and coordination, geographic information science, computer science, etc. Siting decisions are constantly iterated and updated as the discipline evolves, and the dam siting process will inevitably face more challenges.
  • 2.0K
  • 24 Aug 2021
Topic Review
Billing (Filmmaking)
Billing is a performing arts term used in referring to the order and other aspects of how credits are presented for plays, films, television, or other creative works. Information given in billing usually consists of the companies, actors, directors, producers, and other crew members.
  • 2.0K
  • 14 Nov 2022
Topic Review
COP9 Signalosome
The COP9 signalosome (CSN) is a regulator of the ubiquitin proteasome system (UPS). In mammalian cells it occurs as an eight-subunit protein complex, six Proteasome-COP9 signalosome-Initiation factor eIF3 (PCI)-domain subunits including CSN1-4, CSN7 and CSN8 and two MOV34-Pad1-N-terminal (MPN)-domain subunits called CSN5 and CSN6. The CSN regulates cullin-RING-ubiquitin ligases (CRLs) by specifically removing NEDD8 from cullins. In cooperation with CAND1 it controls the adaptation of the CRL network to fluctuations in substrate availability. The CSN complex belongs to the JAMM family of deubiquitylating enzymes (DUBs). In addition, it interacts with other deubiquitylating enzymes including USP15 and USP48 coordinating ubiquitylation and deubiquitylation activities.
  • 2.0K
  • 26 Oct 2020
Topic Review
Dermatophyte Infections
The burden of fungal infections is not widely appreciated. Although these infections are responsible for over one million deaths annually, it is estimated that one billion people are affected by severe fungal diseases. Mycoses of nails and skin, primarily caused by fungi known as dermatophytes, are the most common fungal infections. Trichophyton rubrum appears to be the most common causative agent of dermatophytosis, followed by Trichophyton interdigitale. An estimated 25% of the world’s population suffers from dermatomycosis. Although these infections are not lethal, they compromise the quality of life of infected patients. The outcome of antidermatophytic treatments is impaired by various conditions, such as resistance and tolerance of certain dermatophyte strains.
  • 2.0K
  • 22 Sep 2021
Topic Review
Distribution of Sulfate-Reducing Bacteria in the Environment
Sulfate-reducing bacteria (SRB) are a heterogeneous group of anaerobic microorganisms that play an important role in producing hydrogen sulfide not only in the natural environment, but also in the gastrointestinal tract and oral cavity of animals and humans.
  • 2.0K
  • 25 Oct 2021
Topic Review
Tourist Value Lead to Loyalty
The perceived value of a tourist’s trip, representing a trade-off between costs and benefits of travelling to a destination, can exert a significant influence on tourists’ loyalty, which is a main concern for managers of tourist destinations.
  • 2.0K
  • 25 May 2022
Topic Review
Ultraviolet Reactors for Nonsolid Food Pasteurization
UV-C is an increasingly popular option for the pasteurization of non-solid plant-based foods because it is germicidal, economical, and environmentally-friendly. It is a proven alternative to conventional thermal processes for inactivating microorganisms.UV-C irradiation in nonsolid foods can be performed in equipment that either uses batch or continuous operation modes.
  • 2.0K
  • 30 Aug 2023
Topic Review
cAMP-Response Element Modulator in Spermatogenesis and Male Fertility
Spermatogenesis is a very complex process with an intricate transcriptional regulation. The transition from the diploid to the haploid state requires the involvement of specialized genes in meiosis, among other specific functions for the formation of the spermatozoon. The transcription factor cAMP-response element modulator (CREM) is a key modulator that triggers the differentiation of the germ cell into the spermatozoon through the modification of gene expression. CREM has multiple repressor and activator isoforms whose expression is tissue-cell-type specific and tightly regulated by various factors at the transcriptional, post-transcriptional and post-translational level. The activator isoform CREMτ controls the expression of several relevant genes in post-meiotic stages of spermatogenesis. In addition, exposure to xenobiotics negatively affects CREMτ expression, which is linked to male infertility. On the other hand, antioxidants could have a positive effect on CREMτ expression and improve sperm parameters in idiopathically infertile men.
  • 2.0K
  • 01 Nov 2023
Topic Review
Microbial Electrolysis Cell as a Diverse Technology
Microbial electrolysis cells (MECs) have been explored for various applications, including the removal of industrial pollutants, wastewater treatment chemical synthesis, and biosensing. On the other hand, MEC technology is still in its early stages and faces significant obstacles regarding practical large-scale implementations. MECs are used for energy generation and hydrogen peroxide, methane, hydrogen/biohydrogen production, and pollutant removal. 
  • 2.0K
  • 19 Apr 2022
Topic Review
Mid-Upper Arm Circumference to Predict Malnutrition
The double burden of malnutrition (under- and overnutrition) is a serious public health issue in childhood. The mid-upper arm circumference (MUAC) is a simple tool for screening nutritional status, but studies of the optimal cutoff to define malnutrition are limited. This study aimed to explore the prediction of malnutrition by MUAC in Sri Lankan schoolchildren. The participants were 538 students (202 boys, 336 girls) aged 5–10 years. Spearman’s rank correlation was calculated for MUAC and both body-mass-index-for-age z-score (BAZ) and height-for-age z-score (HAZ). Receiver operating characteristic (ROC) analysis was conducted to assess the ability of MUAC to correctly classify malnutrition, after stratifying for age and birth weight. MUAC correlated significantly with BAZ (r = 0.84) and HAZ (r = 0.35). The areas under the ROC curve for thinness, overweight, obesity, and stunting were 0.88, 0.97, 0.97, and 0.77, respectively. The optimal MUAC cutoff values for predicting thinness and stunting were 167.5 mm and 162.5 mm, respectively; the optimal cutoffs for predicting overweight and obesity were 190.5 mm and 218.0 mm, respectively. These cutoffs differed after stratification by age group and birth weight. Our results confirm MUAC to be a useful tool for monitoring growth in schoolchildren.
  • 2.0K
  • 30 Oct 2020
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