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Topic Review
Melanin
Melanin (/ˈmɛlənɪn/ (listen); from Greek: μέλας, romanized: melas, lit. 'black, dark') is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino acid tyrosine is followed by polymerization. The melanin pigments are produced in a specialized group of cells known as melanocytes. Functionally, eumelanin serves as protection against UV radiation. Melanin (neuromelanin) functions as the catalyst of all cellular functions within an organism. There are five basic types of melanin: eumelanin, pheomelanin, neuromelanin, allomelanin and pyomelanin. The most common type is eumelanin, of which there are two types— brown eumelanin and black eumelanin. Pheomelanin, which is produced when melanocytes are malfunctioning due to derivation of the gene to its recessive format is a cysteine-derivative that contains polybenzothiazine portions that are largely responsible for the of red yellow tint given to some skin or hair colors. Neuromelanin is found in the brain. Research has been undertaken to investigate its efficacy in treating neurodegenerative disorders such as Parkinson's. Allomelanin and pyomelanin are two types of nitrogen-free melanin. In the human skin, melanogenesis is initiated by exposure to UV radiation, causing the skin to darken. Eumelanin is an effective absorbent of light; the pigment is able to dissipate over 99.9% of absorbed UV radiation. Because of this property, eumelanin is thought to protect skin cells from UVA and UVB radiation damage, reducing the risk of folate depletion and dermal degradation. It is considered that exposure to UV radiation is associated with increased risk of malignant melanoma, a cancer of melanocytes (melanin cells). Studies have shown a lower incidence for skin cancer in individuals with more concentrated melanin, i.e. darker skin tone.
  • 2.8K
  • 28 Sep 2022
Topic Review
List of Minerals D (Complete)
This list includes those recognised minerals beginning with the letter D. The International Mineralogical Association is the international group that recognises new minerals and new mineral names, however minerals discovered before 1959 did not go through the official naming procedure, although some minerals published previously have been either confirmed or discredited since that date. This list contains a mixture of mineral names that have been approved since 1959 and those mineral names believed to still refer to valid mineral species (these are called "grandfathered" species). The list is divided into groups: The data was exported from mindat.org on 29 April 2005; updated up to 'IMA2018'. The minerals are sorted by name, followed by the structural group (rruff.info/ima and ima-cnmnc by mineralienatlas.de, mainly) or chemical class (mindat.org and basics), the year of publication (if it's before of an IMA approval procedure), the IMA approval and the Nickel–Strunz code. The first link is to mindat.org, the second link is to webmineral.com, and the third is to the Handbook of Mineralogy (Mineralogical Society of America).
  • 2.8K
  • 05 Nov 2022
Topic Review
Antimicrobial Resistance in the Pseudomonas fluorescens Complex
Pseudomonas spp. are ubiquitous microorganisms that exhibit intrinsic and acquired resistance to many antimicrobial agents. Pseudomonas aeruginosa is the most studied species of this genus due to its clinical importance. In contrast, the Pseudomonas fluorescens complex consists of environmental and, in some cases, pathogenic opportunistic microorganisms. The P. fluorescens complex comprises eight groups occupying various ecological niches, namely P. fluorescens, P. gessardii, P. fragi, P. mandelii, P. koreensis, P. jessenii, P. corrugata, and P. chlororaphis.
  • 2.8K
  • 08 Aug 2022
Topic Review
Egyptian Honeybee
The Egyptian honeybee (Apis mellifera lamarckii) is one of the honeybee subspecies known for centuries since the ancient Egypt civilization. The subspecies of the Egyptian honeybee is distinguished by certain traits of appearance and behavior that were well-adapted to the environment and unique in a way that it is resistant to bee diseases, such as the Varroa disease. The subspecies is different than those found in Europe and is native to southern Egypt.
  • 2.8K
  • 21 Oct 2022
Topic Review
Rooftop Photovoltaic Power Station
A rooftop photovoltaic power station, or rooftop PV system, is a photovoltaic (PV) system that has its electricity-generating solar panels mounted on the rooftop of a residential or commercial building or structure. The various components of such a system include photovoltaic modules, mounting systems, cables, solar inverters and other electrical accessories. Rooftop mounted systems are small compared to ground-mounted photovoltaic power stations with capacities in the megawatt range, hence being a form of distributed generation. Most rooftop PV stations in developed countries are Grid-connected photovoltaic power systems. Rooftop PV systems on residential buildings typically feature a capacity of about 5 to 20 kilowatts (kW), while those mounted on commercial buildings often reach 100 kilowatts to 1 Megawatt (MW). Very large roofs can house industrial scale PV systems in the range of 1-10 Megawatts.
  • 2.8K
  • 17 Nov 2022
Topic Review
Voltage Lifting Techniques for Non-Isolated DC/DC Converters
The conventional boost DC/DC converter is used to step up the input voltage to a desired higher level within the practical limit required by the load with very few components. Stepping up the voltage is achieved by storing the energy in the inductor and releasing it to the output at a higher voltage. The boost converter is very popular for capacitive load applications such as photo-flashers and battery chargers. It is also used in automotive applications, power amplifiers, adaptive control applications, battery power systems, consumer electronics, DC motor drives and power factor correction circuits.
  • 2.8K
  • 02 Mar 2023
Topic Review
Lavender Essential Oil
The producers of essential oils from the Republic of Moldova care about the quality of their products and at the same time, try to capitalize on the waste from processing. The purpose of the present study was to analyze the chemical composition of lavender (Lavanda angustifolia L.) essential oil and some by-products derived from its production (residual water, residual herbs), as well as to assess their “in vitro” antimicrobial activity. The gas chromatography-mass spectrometry analysis of essential oils produced by seven industrial manufacturers led to the identification of 41 constituents that meant 96.80–99.79% of the total. The main constituents are monoterpenes (84.08–92.55%), followed by sesquiterpenes (3.30–13.45%), and some aliphatic compounds (1.42–3.90%). The high-performance liquid chromatography analysis allowed the quantification of known triterpenes, ursolic, and oleanolic acids, in freshly dried lavender plants and in the residual by-products after hydrodistillation of the essential oil. The lavender essential oil showed good antibacterial activity against Bacillus subtilis, Pseudomonas fluorescens, Xanthomonas campestris, Erwinia carotovora at 300 μg/mL concentration, and Erwinia amylovora, Candida utilis at 150 μg/mL concentration, respectively. 
  • 2.8K
  • 14 Sep 2021
Topic Review
Molecular Iodine Has Extrathyroidal Effects
Most investigations of iodine metabolism in humans and animals have focused on its role in thy-roid function. However, considerable evidence indicates that iodine could also be implicated in the physiopathology of other organs.
  • 2.8K
  • 23 Feb 2021
Topic Review
Applications of Magnesium and Alloys
Since its discovery, magnesium has played an influential role in society. In its early days, military applications and wars fueled its growth. For example, magnesium was weaponized to construct incendiary bombs, flares, and ammunitions that were subsequently deployed in World War II, and it caused massive conflagrations and widespread devastations. Post-War, magnesium’s availability and unique blend of properties were explored and were found to be highly attractive for an extensive range of applications. Today, magnesium is used for engineering applications in automotive, aerospace, and consumer electronics. In addition, it has a role in organic chemistry and pharmaceuticals and is used to construct several general-purpose applications, such as sporting goods, household products, and office equipment.
  • 2.8K
  • 09 Oct 2021
Topic Review
Lithium Recovery from Lithium-Ion Battery
Lithium-ion batteries are becoming an integral part of renewable-based energy systems that helps to provide an efficient and greener solution for energy storage. LIBs have found their use in a variety of applications ranging from portable electronic devices to energy grid systems. Owing to the reduction in carbon dioxide emission and improved energy to fuel weight ratio, LIBs have also been widely used in electronic vehicles. LIBs have been especially desirable in this case due to their high charge to mass potential in comparison to other battery types. In the recent decade, the extensive use of LIBs has posed not only a great threat to the world’s lithium resource depletion but also the prevailing problem concerning the consumed and non-recycled LIBs. Hence, immediate attention to alleviate any danger to the ecosystems due to the release of harmful chemicals is required. 
  • 2.8K
  • 12 Apr 2022
Topic Review
Resistance Theory in the Early Modern Period
Resistance theory is an aspect of political thought, discussing the basis on which constituted authority may be resisted, by individuals or groups. In the European context it came to prominence as a consequence of the religious divisions in the early modern period that followed the Protestant Reformation. Resistance theories could justify disobedience on religious grounds to monarchs, and were significant in European national politics and international relations in the century leading up to the Peace of Westphalia of 1648. They can also underpin and justify the concept of revolution as now understood. The resistance theory of the early modern period can be considered to predate the formulations of natural and legal rights of citizens, and to co-exist with considerations of natural law. Any "right to resist" is a theory about the limitations on civil obedience. Resistance theory is an aspect of political theory; the right of self-defence is usually taken to be a part of legal theory, and was no novelty in the early modern period. Arguments about the two concepts do overlap, and the distinction is not so clear in debates.
  • 2.8K
  • 26 Oct 2022
Topic Review
Corey-Seebach Reagent in the 21st Century
The Corey-Seebach reagent plays an important role in organic synthesis because of its broad synthetic applications. The Corey-Seebach reagent is formed by the reaction of an aldehyde or a ketone with 1,3-propane-dithiol under acidic conditions, followed by deprotonation with n-butyllithium. A large variety of natural products (alkaloids, terpenoids, and polyketides) can be accessed successfully by utilizing this reagent.
  • 2.8K
  • 30 May 2023
Topic Review
Escherichia coli in Secondary Habitats
Escherichia (E.) coli are rod shaped, facultative anaerobic, gram-negative, coliform, fecal gammaproteobacteria that inhabit the intestines of endotherms (primary habitat) and the natural environment (secondary habitats). Due to historic thinking regarding the limited capacity of E. coli to survive in the environment, a great deal of research is needed to advance understanding of environmental factors influencing E. coli’s survival.
  • 2.8K
  • 27 Oct 2020
Topic Review
Urinary Biomarkers for Bladder Cancer
Blue light cystoscopy (BLC) is the most recent clinical approach in the detection and diagnosis of bladder cancer, a common type of cancer with a high rate of recurrence. Representing a significant advance over previous approaches, this photodynamic diagnostic technique uses a photosensitiser prodrug as an adjunct to white light cystoscopy to enhance the in vivo detection of malignant tissues in the bladder based on their distinctive fluorescence. Whilst it does improve detection rates, BLC remains an invasive and costly procedure. Meanwhile, a variety of noninvasive urine detection methods and related microdevices have been developed.  In the following section, we provide the current context for urinary biomarker testing, including commercially available tests and recent development involving microdevices.
  • 2.8K
  • 27 Oct 2020
Topic Review
Lipocalin-2
Lipocalin-2 (LCN2), which is a part of the lipocalin transport protein family, is a protein formally known for its role in iron transport and in inflammatory response.
  • 2.8K
  • 27 May 2021
Topic Review
Digital Village Implementations
Digital village is a social entity concept formed by community awareness, and a desire to think beyond and build a new form of cooperation and alliances using advanced digital technologies. It is not only incorporating digitalization into the village, but also forming a social entity that can address the problems existing within the village.
  • 2.8K
  • 17 May 2023
Topic Review
Pitch Control Technique for Horizontal Axis Wind Turbines
In recent years, the increasing environmental problems, especially the issue of global warming, have motivated demand for a cleaner, more sustainable, and economically viable energy source. In this context, wind energy plays a significant role due to the small negative impact it has on the environment, which makes it among the most widespread potential sustainable renewable fuel nowadays. However, wind turbine control systems are important factors in determining the efficiency and cost-effectiveness of a wind turbine (WT) system for wind applications.
  • 2.8K
  • 12 Oct 2023
Topic Review
Effects of Alcohol Withdrawal in Hypertension
Alcoholic beverages are common components of diets worldwide and understanding their effects on humans’ health is crucial. Because hypertension is the leading risk factor for cardiovascular diseases and all-cause mortality. Two different clinical conditions can result from the interruption of alcohol consumption. In heavy alcohol drinkers, abrupt interruption of alcohol intake might result in an alcohol withdrawal syndrome (AWS), with a critical condition that might require hospitalization. Alternatively, chronic reduction/interruption of alcohol intake could be part of the lifestyle changes that are recommended for the achievement of better blood pressure control in hypertensive patients.
  • 2.8K
  • 24 Feb 2023
Topic Review
Pichia kluyveri in Wine Technology
The surfaces of grapes are covered by different yeast species that are important in the first stages of the fermentation process. In recent years, non-Saccharomyces yeasts such as Torulaspora delbrueckii, Lachancea thermotolerans, Metschnikowia pulcherrima, and Pichia kluyveri have become popular with regard to winemaking and improved wine quality. For that reason, several manufacturers started to offer commercially available strains of these non-Saccharomyces species. P. kluyveri stands out, mainly due to its contribution to wine aroma, glycerol, ethanol yield, and killer factor. 
  • 2.8K
  • 18 Feb 2021
Topic Review
Fibromyalgia Syndrome
Pain has a multidimensional nature in which three dimensions are usually differentiated: the sensory-discriminative, the emotional-affective and the cognitive-evaluative. Based on the duration, it is possible to distinguish between acute pain, when it is present for a period lower than 6 months; or chronic pain, if pain is present more than 6 months. Fibromyalgia Syndrome is a complex chronic pain disorder in which widespread and persistent musculoskeletal pain is accompanied by different symptoms such as fatigue, insomnia, morning stiffness, depression, anxiety and cognitive impairments. Fibromyalgia began to be studied from the 16th century and it received different names during its historical development. The main landmarks in the development of fibromyalgia term include -among others- when the French physician Guillaume de Baillou in 1642 provided the first description of the disease using the term “muscular rheumatism”. The British neurologist W.R. Gowers in 1904 coined the term “fibrositis” in an article on lumbago. In 1944, F. Elliot suggested that the pain experimented by fibromyalgia patients might involve the spinal cord and thalamus. In 1968, E.F. Traut stated the first near-modern description of fibromyalgia with systemic features. In 1976, the term fibromyalgia was coined by P.K. Hench as a form of non-articular rheumatism based on the absence of specific inflammatory damage. In 1977, H.A. Smythe and H. Moldofsky continued the work of P.K. Hench and proposed the first measure for evaluating fibromyalgia. Nevertheless, it was not until 1981 that the medical community accepted this disease under the term "fibrositis" or “fibromyalgia” thanks to the work of Yunus et al. The distinction between primary and secondary fibromyalgia disappeared sometime later. During the 1980s, different authors suggested other formal and ad-hoc criteria sets. In 1987, the American Medical Association accepted fibromyalgia as a real disease. Shortly thereafter and as a result of this recognition, the American College of Rheumatology (ACR) created a committee to establish the diagnostic criteria for this disorder. The first official diagnostic criteria were proposed in 1990 by the ACR. In 1994, fibromyalgia was also recognized by the International Association for the Study of Pain. During the 1990s, there was an increase in fibromyalgia research. In 2010, the ACR proposed a new version of the diagnostic criteria based exclusively on the use of the Widespread Pain Index and the Symptom Severity Scale. In addition, other two subsequent diagnostic proposals were performed. In 2011, Wolfe et al. revised and modified the 2010 ACR diagnostic criteria to facilitate its use in epidemiological or community studies, but not for self-diagnosis in the clinical context. In 2016, ACR criteria were proposed to combine the 2010 and 2011 ACR criteria into a single set to overcome the previous limitations. Definitely, fibromyalgia involves high personal, family and financial costs. Fibromyalgia also implies high economic costs for the socio-health system. Fibromyalgia notably reduces perceived functioning in physical, psychological, and social spheres, and has a negative impact on personal relationships, parenting, work, daily activities, mental health and social relationships.
  • 2.8K
  • 05 Nov 2020
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