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Topic Review
α Cell in Diabetes Pathogenesis
The involvement of impaired alpha (α) cell function has been recognized as playing an essential role in several diseases, since hyperglucagonemia has been evidenced in both Type 1 and T2DM. This phenomenon has been attributed to intra-islet defects, like modifications in pancreatic α cell mass or dysfunction in glucagon’s secretion. Emerging evidence has shown that chronic hyperglycaemia provokes changes in the Langerhans’ islets cytoarchitecture, including α cell hyperplasia, pancreatic beta (β) cell dedifferentiation into glucagon-positive producing cells, and loss of paracrine and endocrine regulation due to β cell mass loss. Other abnormalities like α cell insulin resistance, sensor machinery dysfunction, or paradoxical ATP-sensitive potassium channels (KATP) opening have also been linked to glucagon hypersecretion. 
  • 417
  • 27 Oct 2021
Topic Review
Zwitterionics Surfactants
Zwitterions are molecules that contain both a positive and negative charge within the same molecule. They are electrically neutral as a whole, but have distinct positive and negative regions within the molecule. The most common example of a zwitterion is the amino acid molecule, which contains both a carboxyl group (-COOH) and an amino group (-NH2) within the same molecule. The carboxyl group is negatively charged at physiological pH, while the amino group is positively charged, resulting in a net charge of zero for the molecule as a whole. Zwitterions have unique properties that make them useful in various applications. They are often used as buffer solutions in biochemistry and molecular biology, as they can maintain a stable pH even when small amounts of acid or base are added. Zwitterions are also used as surfactants, due to their amphipathic nature (i.e. they have both hydrophilic and hydrophobic regions). They are used in applications such as detergents and fabric softeners, where they can help to reduce surface tension and improve the wetting and dispersibility of the product. Zwitterionic surfactants have a unique structure that allows them to interact with a wide range of substances, making them useful in various applications. The unique combination of positive and negative charges in the same molecule provides a balance that enables them to interact with both hydrophilic and hydrophobic substances, allowing them to solubilize oils and greases, emulsify water-insoluble substances, and reduce surface tension.
  • 1.9K
  • 24 Mar 2023
Topic Review
Zwitterionic Dental Biomaterials
Biofilms are formed on surfaces inside the oral cavity covered by the acquired pellicle and develop into a complex, dynamic, microbial environment. Oral biofilm is a causative factor of dental and periodontal diseases. Accordingly, novel materials that can resist biofilm formation have attracted significant attention. Zwitterionic polymers (ZPs) have unique features that resist protein adhesion and prevent biofilm formation while maintaining biocompatibility. Recent literature has reflected a rapid increase in the application of ZPs as coatings and additives with promising outcomes. 
  • 5.9K
  • 29 Dec 2020
Topic Review
Zuytdorp
The VOC Zuytdorp also Zuiddorp (meaning "South Village", after Zuiddorpe, a still existing village in the South of Zeeland, near the Belgian border) was an 18th-century trading ship of the Dutch East India Company (Vereenigde Oost-Indische Compagnie, commonly abbreviated VOC). On 1 August 1711 it was dispatched from the Netherlands to the trading port of Batavia (now Jakarta, Indonesia) bearing a load of freshly minted silver coins. Many trading ships of the time travelled a "fast route" using the strong Roaring Forties winds to carry them across the Indian Ocean to within sight of the west coast of Australia, (then called New Holland) whence they would make a turn north towards Batavia. The Zuytdorp never arrived at its destination. No search was undertaken, presumably because the VOC had no idea whether and where the ship had been wrecked or taken by pirates and possibly due to prior expensive but fruitless attempts to search for other missing ships, even when an approximate wreck location was known. As a result Zuytdorp and its entire complement were never heard from again. Their fate was unknown until the mid-20th century when the wreck site was identified on a remote part of the Western Australian coast between Kalbarri and Shark Bay, approximately 40 km north of the Murchison River. This rugged section of coastline was subsequently named the Zuytdorp Cliffs, was the preserve of the Indigenous inhabitants and one of the last great wildernesses until the advent of the sheep stations established there in the late 19th century. Something, perhaps a violent storm, occurred and the Zuytdorp was wrecked on a desolate section of the West Australian coast. Survivors scrambled ashore and camped near the wreck site. With no European settlements anywhere on the coast they built bonfires from the wreckage to signal fellow trading ships that would pass within sight of the coast. But fires seen in the vicinity tended to be dismissed as "native fires" as appears to have happened in the case of Vergulde Draeck in 1656. It has been speculated that survivors may have traded with or may have intermarried with the local Aboriginal communities between present-day Kalbarri and Shark Bay. It is also possible that intermarriage occurred in the case of a predecessor to the Zuytdorp, the infamous VOC Batavia, wrecked on the Houtman Abrolhos islands offshore. After a mutiny, atrocities, massacres and trials, two of the mutineers were marooned on the Australian mainland, near the Murchison River (for details about these two mutineers see castaway). News of an unidentified shipwreck on the shore surfaced in 1834 when Aborigines told a farmer near the recently colonised Perth about a wreck the colonists presumed it was a recent wreck and sent rescue parties who failed to find the wreck or any survivors. The details provided (90 days walk, and coins on the beach), tend to point to the Zuytdorp; however. In 1927, wreckage was seen by an Indigenous-European family group (comprising Ada and Ernest Drage, Tom and Lurleen Pepper and the women's father Charlie Mallard) on a clifftop near the border of Murchison house and Tamala Stations where they all worked. Tamala Station head stockman, Tom Pepper later reported the find to the authorities, their first expedition to the site occurring in 1941. In 1954 Pepper gave Phillip Playford directions and it was he who subsequently identified the relics as from Zuytdorp.
  • 607
  • 30 Sep 2022
Topic Review
Zuotin-Related Factor 1
Recently, Zuotin-related factor 1 (ZRF1), an epigenetic regulator, was found to be involved in transcriptional regulation. In animals and humans, ZRF1 specifically binds to monoubiquitinated histone H2A through a ubiquitin-binding domain and derepresses Polycomb target genes at the beginning of cellular differentiation. In addition, ZRF1 can work as a tumor suppressor. According to bioinformatics analysis, ZRF1 homologs are widely found in plants.
  • 632
  • 18 Aug 2021
Topic Review
ZrO2—CeO2 Ceramics Doped with Yttrium
The synthesis of ZrO2—CeO2 ceramics was carried out using solid-phase mechanochemical synthesis followed by thermal sintering of the obtained mixtures. ZrO2 and CeO2 powders in equal mole fractions (0.5:0.5) were chosen as initial components for synthesis. 
  • 486
  • 28 Mar 2022
Topic Review
ZrB2 Nanopowders Solid-State Synthesis
ZrB2 is of particular interest among ultra-high temperature ceramics because it exhibits excellent thermal resistance at high temperature, as well as chemical stability, high hardness, low cost, and good electrical and thermal conductivity, which meet the requirements of high-temperature components of hyper-sonic aircraft in extreme environments. In recent years, the development of ZrB2 powders’ synthesis method has broken through the classification of traditional solid-phase method, liquid-phase method, and gas-phase method, and there is a trend of integration of them. Solid-state synthesis, including the borothermic reduction method, carbothermic reduction method, and metallothermic reduction method, is mostly used because the process is simple and the raw materials are cheap and easily available. 
  • 898
  • 26 Oct 2021
Topic Review
Zoroastrianism in India
Zoroastrianism in India has significant history within the country. The initial migration following the Muslim conquest of Persia has been canonized as a religious persecution by invading Muslims. Zoroastrianism meanwhile suffered a decline in Iran after the conquests. Subsequent migrations also took place after the attempts by Safavids to convert their subjects to Shiism. Due to persecution of Zoroastrians in other countries and the liberal atmosphere and patronisation of India, today the largest population of Zoroastrians resides in India, where Zoroastrians have been allowed to play a notable role in the Indian economy, entertainment, the armed forces, and the Indian freedom movement during British Raj. The Zoroastrian groups are regarded as either Parsi or Irani depending on the time of migration to India.
  • 1.4K
  • 09 Nov 2022
Topic Review
Zoos as Conservation Institutions
Zoological institutions, which were once exclusively for entertainment, are now leaders of wildlife conservation. This centuries-long transition was punctuated by key milestones that reformed wild animal exploitation into a mission of protection. Modern zoos perform ex situ activities to preserve natural resources, which are enabled by the housing of wild species. Zoo-managed animals facilitate new scientific knowledge, public education, and strategic breeding to maintain genetic diversity.
  • 521
  • 30 Nov 2023
Topic Review
Zooplankton for Monitoring and Assessing Lake Ecosystem Health
For the sustainable use of lake ecosystem services—water resources, aquatic habitats for biodiversity conservation, and aesthetic values as waterfront space—ecosystem health assessments using biota are implemented as important national environmental monitoring projects. Zooplankton play a key role as an important linkage in the material circulation as secondary producers in lake ecosystems. At the same time, they influence the composition and biomass of other communities through biological interactions.
  • 629
  • 27 Jul 2023
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