In science and engineering, the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they are pure numbers with no associated units of measurement. Commonly used are parts-per-million (ppm, 10−6), parts-per-billion (ppb, 10−9), parts-per-trillion (ppt, 10−12) and parts-per-quadrillion (ppq, 10−15). This notation is not part of the International System of Units (SI) system and its meaning is ambiguous. Overview Parts-per notation is often used describing dilute solutions in chemistry, for instance, the relative abundance of dissolved minerals or pollutants in water. The quantity "1 ppm" can be used for a mass fraction if a water-borne pollutant is present at one-millionth of a gram per gram of sample solution. When working with aqueous solutions, it is common to assume that the density of water is 1.00 g/mL. Therefore, it is common...

Nevada’s COVID-19 safety protocols remain in place, but events show several tourist areas crowded with tourists, many of them not wearing masks.

It was a dairy good time for plenty of readers missing one of the beloved traditions of the Minnesota State Fair — the sculpting of Princess Kay of the Milky Way and her court in 90-pound blo…

The British government is planning legislation that will override key parts of the Brexit withdrawal agreement, risking the collapse of trade negotiations with Brussels, the Financial Times reporte…

Today’s Top Supply Chain & Logistics News from WSJ.

After the weekend’s brutal heat wave subsides, windy fire weather may arrive — and PG&E could cut the power to parts of Napa and Sonoma counties to prevent its equipment from sparking fires.

Amid a blistering heat wave, Bay Area residents readied themselves for a more ominous forecast: dangerous wind gusts predicted to hit the region's bone-dry mountains and hills by Monday night.

Improving your posture takes a little work and patience, but it's well worth it–good posture can help you look and feel better. If you want to stop slouching or get relief from back pain, start to work on your posture in all parts of your...

A mailing list is a collection of names and addresses used by an individual or an organization to send material to multiple recipients. The term is often extended to include the people subscribed to such a list, so the group of subscribers is referred to as "the mailing list", or simply "the list". Transmission may be paper-based or electronic. Each has its strengths, although a 2022 article claimed that "direct mail still brings in the lion's share of revenue for most organizations." Types At least two types of mailing lists can be defined: an announcement list is closer to the original sense, where a "mailing list" of people was used as a recipient for newsletters, periodicals or advertising. Traditionally this was done through the postal system, but with the rise of email, the electronic mailing list became popular. This type of list is used primarily as a one-way conduit of information and may only be "posted to" by selected people. This may also be referred to by the term newsletter. Newsletter and promotional emailing lists are employed in various sectors as parts of direct marketing campaigns...