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Topic Review
Microwave-Assisted Post-Ugi Reactions for the Synthesis of Polycycles
Microwave-assisted post-Ugi reactions have been employed for the synthesis of diverse polycycles. From commercially available starting materials, transition metal-catalyzed or transition metal-free transformations are performed in an efficient, rapid, and step-economical manner. With the help of microwave irradiation, linear Ugi-adducts are converted into more complex drug-like polycycles with high chemo-, regio-, and stereoselectivity, exhibiting the robustness and potential of this strategy and unfolding a large window for organic synthesis.
  • 443
  • 30 May 2022
Topic Review
Weak Polyelectrolytes for Nanoarchitectonic Design Tools
The ionization degree, charge density, and conformation of weak polyelectrolytes can be adjusted through adjusting the pH and ionic strength stimuli. Such polymers thus offer a range of reversible interactions, including electrostatic complexation, H-bonding, and hydrophobic interactions, which position weak polyelectrolytes as key nano-units for the design of dynamic systems with precise structures, compositions, and responses to stimuli. From surface platforms to colloids and gels, weak polyelectrolytes have enabled the development of a wide range of functional materials owing to their intrinsic response to stimuli, including solvents, temperature, pH, and salt.
  • 657
  • 30 May 2022
Topic Review
Quercus suber and Cork By-Products
There is a drive within the cosmetic industry towards the development of more sustainable products, supported by consumer awareness of the environmental footprint. The cosmetic industry is rising to meet consumer demand by following practices, such as the use of by-products from agro-industrial waste. Quercus suber is a tree prevalent in the Mediterranean basin. The extraction of cork is considered sustainable, as this process does not harm the tree, and the amount of cork produced increases with the number of extractions. Beyond this, the cork industry produces by-products that are used to sustain the industry itself, such as cork powder, which is reused for generating energy. Additionally, cork and cork by-products contain bioactive compounds mainly with antioxidant activity that can be of use to the cosmetic industry, such as for antiaging, anti-acne, anti-inflammatory, and depigmenting cosmetic products.
  • 491
  • 30 May 2022
Topic Review
Untargeted Human Milk Metabolomics
Human milk (HM) is considered the gold standard for infant nutrition. HM contains macro- and micronutrients, as well as a range of bioactive compounds (hormones, growth factors, cell debris, etc.). The analysis of the complex and dynamic composition of HM has been a permanent challenge for researchers. The use of novel, cutting-edge techniques involving different metabolomics platforms has permitted to expand knowledge on the variable composition of HM. Here, the state-of-the-art in untargeted metabolomic studies of HM, with emphasis on sampling, extraction and analysis steps is presented.
  • 1.1K
  • 30 May 2022
Topic Review
Modern Near-Infrared Instrumentation
The ongoing miniaturization of spectrometers creates a perfect synergy with the common advantages of near-infrared (NIR) spectroscopy, which together provide particularly significant benefits in the field of food analysis. The combination of portability and direct onsite application with high throughput and a noninvasive way of analysis is a decisive advantage in the food industry, which features a diverse production and supply chain. A miniaturized NIR analytical framework is readily applicable to combat various problems encountered in modern industry and key sectors of public interest, i.e. food safety risks, agriculture, or environment.
  • 1.8K
  • 30 May 2022
Topic Review
Cross-Coupling-Reaction of Copper Carbene Intermediate with Terminal Alkyne
Copper-catalyzed cross-coupling reaction of a copper carbene intermediate with terminal alkynes was one of the most powerful protocols for the construction of C–C bonds. However, in early works, a mixture of alkynoates and allenoates was generated in combined moderate yields under harsh reaction conditions. Until 2004, Fu reported the first example of the copper-catalyzed coupling reaction of terminal alkynes with diazo esters or diazo amides to yield 3-alkynoate or 3-butynamide products selectively with minimal amount of allene byproducts under no-basic conditions. Consequently, a variety of copper-catalyzed coupling reactions of terminal alkynes with various carbene precursors have been developed independently.
  • 1.1K
  • 30 May 2022
Topic Review
Gas Sensors Based on Titanium Oxides
Nanostructured titanium compounds have recently been applied in the design of gas sensors. Among titanium compounds, titanium oxides (TiO2) are the most frequently used in gas sensing devices. Very recently, the applicability of non-stoichiometric titanium oxide (TiO2−x)-based layers for the design of gas sensors was demonstrated. The most promising titanium compounds and hetero- and nano-structures based on these compounds are discussed and the possibility to tune the sensitivity and selectivity of titanium compound-based sensing layers is addressed.  
  • 861
  • 28 May 2022
Topic Review
Squaraine-Based Fluorescent Materials
Squaraine dyes (SQs) are a peculiar class of cyanine dyes. One of the biggest structure differences between SQs and other types of cyanine dyes is that SQs contain an electron-deficient square ring at the center of the polymethine chain, leading to a quadrupolar donor-acceptor-donor (D-A-D) structure with a unique resonance-stabilized zwitterionic feature, as shown ina. In addition, the central square ring can make the polymethine chain rigid and planar to resist the photoisomerization and oxidation, and thus SQs intrinsically exhibit a greater stability over other cyanines.
  • 425
  • 27 May 2022
Topic Review
Teucrium Taxa Used in Kurdistan Region
Herbal medicine is still widely practiced in the Kurdistan Region, Iraq, especially by people living in villages in mountainous regions. Seven taxa belonging to the genus Teucrium (family Lamiaceae) are commonly employed in the Kurdish traditional medicine, especially to treat jaundice, stomachache and abdominal problems. Teucrium L. is the second-largest genus of the subfamily Ajugoideae in the family Lamiaceae (Labiatae), with a subcosmopolitan distribution and more than 430 taxa with accepted names. Mild climate regions, such as the Mediterranean and the Middle East areas, contain about 90% of the total Teucrium taxa. 
  • 429
  • 27 May 2022
Topic Review
Plant-Derived Natural Products against Common Respiratory Diseases
Currently, the world is more challenged by respiratory diseases (RDs) than it witnessed in the last few decades. This is evident in the plethora of acute and chronic respiratory conditions, ranging from asthma and chronic obstructive pulmonary disease (COPD) to multidrug-resistant tuberculosis, pneumonia, influenza, and more recently, the novel coronavirus (COVID-19) disease. Unfortunately, the emergence of drug-resistant strains of pathogens, drug toxicity and side effects are drawbacks to effective chemotherapeutic management of RDs. The role of natural products (NPs) in drug discovery cannot be over-emphasized. NPs are chemical substances produced by living organisms such as plants, animals, and marine organisms. They are primary and secondary metabolites and may only be isolatable in small quantities from natural sources. Structurally, they range from small molecules, such as thymol, thymoquinone and penicillin, to complex molecules such as tachyplesin I and II, with unique chemical and biological properties. NPs are regarded as the hallmark of modern pharmaceutical care because they continue to provide new leads with novel biological mechanisms of action against emerging diseases.
  • 388
  • 27 May 2022
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