Nashua Community College

Abstract With the rise of the Swiss-born alchemist Paracelsus in the 16th century, the dissolution of cinnabar (red HgS) in aqua regia has repeatedly appeared in the chemical literature. This article reviews the relevant history and takes a thermodynamic approach to shed new light on the dissolution. The conclusions reveal that the reaction in which the sulfide ion is oxidized by nitric acid is the most thermodynamically favorable step in the dissolution. The importance of the role of hydrochloric acid in the dissolution, when it provides complexation, was also observed. Further, it was found that the overall effect of nitric acid is much greater than that of the aqua regia by-product elemental chlorine.

The news of Chinese traditional medicines reaching Iran suggests that these medicines are becoming increasingly available internationally. Despite the long history of the toxic effects of mercury, mercury compounds are commonly used in Chinese traditional medicines. Two mercurials contained in some Chinese traditional medicines are the salts mercury(II) sulfide (HgS) and mercury(I) chloride (Hg2Cl2). Toxicological evidence from the past and principles of reactivity in inorganic chemistry are used to address the human health concern that is caused by Chinese traditional medicines in which either of the two mercury salts is present. The chemistry discussed in this article shows that the ingestion of HgS or Hg2Cl2 causes the introduction of aqueous mercury cations, especially Hg2+, into the human body. With that chemistry discussed and with the addressed toxic effects, science at the present time finds the Chinese traditional medicines that contain HgS or Hg2Cl2 disadvantageous compared to the antibiotics and sedatives that are available in modern medicine today.

The puzzle of a mysterious death in the Middle Ages has been hypothesized in terms of contemporary forensic legal and scientific methods. That al-Hasan ibn-‘Ali died in 669 aged just 45 has been forensically analyzed based on written sources that dictate eyewitness accounts of historical events. The report of the contemporaneous poisoning of another individual who resided under the same household as al-Hasan’s and experienced similar, yet non-lethal, symptoms has served as the beginning of the analysis. In light of ancient (medieval) documents and through using mineralogical, medical, and chemical facts, it has been hypothesized that mineral calomel (mercury(I) chloride, Hg2Cl2) from a certain region in the Byzantine Empire (present-day western Turkey) was the substance primarily responsible for the murder of al-Hasan.

Excessive quantities of atmospheric sulfur dioxide (SO2) are environmentally problematic. One of the anthropogenic processes that release SO2 into the atmosphere is the contact process for the industrial manufacture of sulfuric acid (H2SO4). The progress of the idea to make use of “green vitriol” (FeSO4·7H2O) for “SO2-free” manufacture of H2SO4 is discussed here. The environmentally advantageous fact that the method, called “Geber's method,” can theoretically be “waste-free” is addressed in this “Comment,” and the challenge of having limited suitable resources of FeSO4·7H2O in the US for use as the starting material in “Geber's method” is emphasized.

Designing small molecules useful for the biological chelation of cations like zinc is a possibly beneficial research area in discovering or developing effective natural or synthetic chelating agents. Synthetic chemists need to estimate how strongly the hypothetical cation chelates would bind to the cation before they synthesize them. The most desirable approach is to use quantitative structure–property relationships (QSPRs) to predict binding constants using elemental composition and functional group data only. This article develops a QSPR for predicting zinc binding by organic ligands, including thiol-containing ligands. The QSPR has the desired Spred of ~1 log unit and an Adjusted R2 of 0.934. It is a simple mathematical relationship which allows predicting binding constants of zinc with small organic molecules robustly using minimal structural information about the molecules. Therefore, it is suitable for use with small natural or synthetic organic ligands as hypothetical therapeutic agents, provided that an accuracy of ±1 log unit in the conditional binding constants is acceptable.

Image analysis tools are currently in use for a variety of applications in the fields of forensics and security printing. Objective, quantitative data allow for characterization and comparison of a variety of image attributes.In forensics, document examiners can use quantitative image analysis systems in authentication, detection and analysis of forgeries, counterfeits and altered documents. Statistical analysis enables population characterization that can help in forgery detection and supports the potential for source identification. In security printing, image analysis tools can be applied to measure the quality of printed output and assess wear for bank notes.Flexible hardware options allow for a broad application of image quality measurements in a variety of image analysis situations. Camera and scanner-based image quality systems can be used for quantitative analysis of image content. A laser-based system can be used for height and depth profiling. Oblique angle illumination and scanning can be used for impression detection. A flatbed scanner can be used in transmission mode for the evaluation of bank note wear and for watermark analysis.In this paper, we will be discussing the use of a variety of hardware configurations for image analysis in forensics and security printing.