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Topic Review
Prehistoric Paintings in Magura Cave
The paintings are made of bat guano applied over limestone, therefore two sets of laboratory specimens were considered: stone specimens and stone specimens covered with a layer of sterilized bat guano. The two investigated treatments were a commercial product based on ethyl silicate (“ES”) and a solution of diammonium hydrogen phosphate (“DAP”), aimed at forming calcium phosphates. The results of the study indicate that both treatments were able to increase mechanical properties of stone, the increase being higher for “DAP”. Both consolidants caused acceptable color changes, but the “ES” treatment significantly decreased stone wettability, water absorption and water vapor permeability, while the “DAP” treatment slightly affected those properties. In the stone+guano specimens, the presence of the guano layer affected the penetration of the consolidants, thus partly reducing their effectiveness. Compared to the stone samples, the guano layer experienced a more intense color change, alongside visible cracking. However, the adopted methodology to replicate the cave paintings was not completely successful, as the so-deposited guano layer was very prone to detachment when dry, unlike cave paintings. Future work will be dedicated to assess the consolidant performance onto samples that resemble even more closely the conditions of the cave paintings, by improving the methodology for the guano layer deposition and by contaminating specimens with soluble salts before consolidant application.
  • 6.3K
  • 02 Nov 2020
Topic Review
Predator Emitted Volatile Organic Compounds in New Zealand
The volatile organic compounds (VOCs) emitted by the bodies and secretions of introduced mammalian predators in New Zealand forests are covered, with a specific focus on mice, rats, ferrets, stoats, and possums.
  • 286
  • 08 Feb 2024
Topic Review
Precipitation
In an aqueous solution, precipitation is the process of transforming a dissolved substance into an insoluble solid from a super-saturated solution. The solid formed is called the precipitate. In case of an inorganic chemical reaction leading to precipitation, the chemical reagent causing the solid to form is called the precipitant. The clear liquid remaining above the precipitated or the centrifuged solid phase is also called the 'supernate' or 'supernatant'. The notion of precipitation can also be extended to other domains of chemistry (organic chemistry and biochemistry) and even be applied to the solid phases (e.g., metallurgy and alloys) when solid impurities segregate from a solid phase.
  • 752
  • 07 Nov 2022
Topic Review
Preceramic Polymers for Additive Manufacturing of Silicate Ceramics
The utilization of preceramic polymers (PCPs) to produce both oxide and non-oxide ceramics has caught significant interest, owing to their exceptional characteristics. Diverse types of polymer-derived ceramics (PDCs) synthesized by using various PCPs have demonstrated remarkable characteristics such as exceptional thermal stability, resistance to corrosion and oxidation at elevated temperatures, biocompatibility, and notable dielectric properties, among others. The application of additive manufacturing techniques to produce PDCs opens up new opportunities for manufacturing complex and unconventional ceramic structures with complex designs that might be challenging or impossible to achieve using traditional manufacturing methods. This is particularly advantageous in industries like aerospace, automotive, and electronics. 
  • 291
  • 19 Dec 2023
Topic Review
Pre-Clinical Evidence of Biodegradable Osteosynthesis Systems
A biodegradable osteosynthesis system should meet two intertwined criteria to be used as an osteosynthesis system: (1) the biomaterial needs to be biocompatible with the host tissue and (2) the mechanical properties should be sufficient for stable fixation of fracture or osteotomy segments during the surgical procedure (primary stability) and during the degradation of the biomaterial, with a gradual transfer of stress to the healing bone
  • 468
  • 14 Jul 2022
Topic Review
PRC200
PRC200-SS is an arylalkanolamine TRI being developed by the Mayo Clinic. Sympathomimetic PRC200-SS is the PRC050 eutomer, whereas PRC201 is the distomer. These compounds are preceded by venlafaxine, which Wyeth claims is the first SNRI. Venlafaxine was originally developed as an "opioid" although original screening returned negative results. The authors were not satisfied just to drop venlafaxine from development and continued with their study of the compounds biological activity data. Herein, they discovered that venlafaxine exerts its biological actions via interaction with the monoamine receptors. In particular, the actions of the drug on increasing the amount of 5-HT and NE were documented, although with "potentiated" analogs such as the pm-dichlorophenyl ring substituted derivative, it might be expected to behave as a SNDRI also (but no data was available to support this inference). Venlafaxine itself has been said to behave as a SNDRI at very high doses. This would be more likely to be the case in drug naïve subjects than in users that have already built up significant tolerance. Silicon containing analog of venlafaxine was prepared and demonstrated to be an active SNRI.
  • 291
  • 11 Oct 2022
Topic Review
Practical Aspects of Nuclear Magnetic Resonance Application
Nuclear magnetic resonance (NMR) is a primary method of measurement according to metrology standards. It has been proven to have good reproducibility. NMR spectra are evaluated numerically, including chemical shifts, coupling constants, and signal integrals, which lead to quantitative results.
  • 340
  • 13 Dec 2023
Topic Review
PPARs in Treatment of Neuropsychiatric Disorders
Peroxisome proliferator-activated receptors (PPARs) are non-steroid nuclear receptors, which dimerize with the retinoid X receptor (RXR) and bind to PPAR-responsive regulatory elements (PPRE) in the promoter region of target genes. Recently, peroxisome proliferator-activated receptor (PPAR)-α and γ isoforms have been gaining consistent interest in neuropathology and treatment of neuropsychiatric disorders. 
  • 633
  • 29 Mar 2022
Topic Review
Power Generation Using Dielectric Elastomers
Power generation using dielectric elastomer (DE) artificial muscle is attracting attention because of its light weight, low cost, and high-efficiency. Since this method is a system that produces electricity without emitting carbon dioxide nor using rare earths, it would contribute to the goal of environmental sustainability. 
  • 1.8K
  • 30 Jun 2021
Topic Review
PowderMEMS
PowderMEMS is a powder-based microfabrication technology for substrate-level integration of three-dimensional functional microstructures into MEMS devices. The PowderMEMS process solidifies micron-sized particles via atomic layer deposition (ALD) in pre-processed cavities on planar substrates from a wide variety of materials. Low process temperatures and the absence of organic components enable back-end-of-line compatibility. The process offers numerous degrees of freedom for the design of functional MEMSs, such as a wide choice of different material properties and the precise definition of 3D volumes at the substrate level, with a defined degree of porosity. Examples of application are the integration of rare-earth magnets and porous microfluidic structures into MEMS on wafer-level.
  • 522
  • 11 Apr 2022
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