#2024daily

[materialsscienceandengineering]

With the start of 2025 comes the end of the 2024Daily posts. Hope you enjoyed the themes this past year!

Safety Sunday

Measurement Monday

Transformation Tuesday

Waste Wednesday

Thermodynamic Thursday

Failure Friday

Scientist Saturday

[materialsscienceandengineering]

Laboratory Incidents: The Importance of Reporting

Laboratory safety cultures are crucial to providing safe work environments, with guidelines, procedures, and emergency responses outlined and detailed whenever possible. Equally important to following the many rules, recommendations, and requirements for lab safety is the task of reporting incidents and near misses. (Where a near miss can be classified as anything where an individual thinks an accident could have occurred, and may be defined differently by various organizations.) Reporting safety incidents allows individuals and organizations to learn from mistakes or gaps in training (or gaps in knowledge regarding the dangers of chemicals or procedures) and improve in the future. Individual health and safety should always be more important than reporting broken equipment or costly mistakes. No matter how small, lab safety incidents should be reported to the proper individuals - and if individuals feel unsafe reporting to their organization, regulatory agencies may offer an alternative.

Examples of reported accidents, incidents, and near misses are detailed in links below, but many other examples and reports exist:

Top Science Mishaps (laboratory accident) Over the Past 60 Years [Image source]

8 Stories of Lab Safety Gone Wrong

When mistakes matter: The worst laboratory accidents

The Laboratory Safety Institute Memorial Wall

Laboratory Accidents [List compiled by UCSB]

Near Misses [List compiled by UCSB]

Lab Incidents - Lessons Learned [List compiled by University of Texas at Austin]

Stay safe everyone! All the SafetySunday posts can be found here.

[materialsscienceandengineering]

The Complexities of Failure Analysis

The failure analysis case studies chosen for this blog over the course of the last year tended to be selected because they had (mostly) clear single causes of failure. Fatigue. Corrosion. An improper design. But failure of materials is complex and there are often multiple contributing factors, including many human factors only hinted at in the stories shared here - corrosion can be caught with proper inspections; improper maintenance can allow a crack to grow.

In addition, failures need not be catastrophic, or occur on quite so grand a scale. The blades in a blender may fail, or a bolt on a lawnmower. The examples presented here are often worst case scenarios, many that resulted in loss of life.

Failure analysis is almost never as simple as deciding upon a single root cause. It requires detailed investigations, often multiple test methods, and ultimately the end result is ambiguous, more often eliminating options than settling on a single cause. Knowing the possible failure mechanisms is crucial, but so is knowing that failure is more complicated than that.

Image source.

All the FailureFriday posts can be found here.

[materialsscienceandengineering]

SI Derived Units: Catalytic Activity and the Katal

The final named SI derived unit we have to discuss is the katal, a measure of catalytic activity primarily used for enzymes (though applicable to other catalysts). Though the term has been used for decades, it was not officially recognized as a unit until 1999. The katal is symbolized by the abbreviation kat and has base units of mol per s, but is not a rate. Instead the katal is defined as "the amount of catalytic activity that facilitates the conversion of one mole of substrate per second, under the specified conditions", with different values arising from different environmental conditions.

Sources/Further Reading: (Wikipedia: Katal; Catalytic activity - image 2) (Metric System - image 1) (IUPAC) (2002 article)

[materialsscienceandengineering]

SI Derived Units: Equivalent Dose and the Sievert

The named SI derived unit of equivalent dose is the sievert, named for Rolf Maximilian Sievert and adopted by the International Committee for Weights and Measures in 1980. While it is, in terms of base units, equivalent to the gray (both are joules per kilogram, or meters squared per seconds squared), the sievert "is a measure of the absorption of ionising radiation energy by human tissue, and includes a qualitative scaling factor to account for the type of radiation involved, and the tissue type affected."

The sievert is symbolized Sv. In CGS units, one sievert is equivalent to 100 rem (roentgen equivalent man).

Sources/Further Reading: (Wikipedia: Sievert - Image source; Equivalent dose) (Metric System) (Radiation Dosimetry) (Nuclear Power)

[materialsscienceandengineering]

The Boltzmann Constant

The Boltzmann constant is a constant that relates temperature and energy. More specifically: "the average relative thermal energy of particles in a gas with the thermodynamic temperature of the gas." It is named after its discoverer, Ludwig Boltzmann, and was officially declared one of the seven defining constants in for SI units in 2019. The value is approximately 1.38x10^-23 J/K.

Sources/Further Reading: (Image source - Wikipedia) (LibreTexts) (NIST)

[materialsscienceandengineering]

SI Derived Units: Absorbed Dose and the Gray

The absorption of ionizing radiation is measured using the named SI derived unit of the gray. The gray was named in honor of Louis Harold Gray in 1975, replacing the previously used unit of the rad (still used in some applications today, and equivalent to one centigray). The symbol for the gray is Gy and it is equivalent to the energy of one joule per kilogram of matter (in SI base units it is m^2 s^-2).

Sources/Further Reading: (Wikipedia: Gray - Image source; Absorbed dose) (Metric System) (Radiation Dosimetry) (NRC)

[materialsscienceandengineering]

SI Derived Units: Radioactivity and the Becquerel

Of the three named SI derived units that deal with radioactivity, the becquerel is the one that is considered the "unit of radioactivity", with one becquerel equivalent to one activity per second. That puts it in base units as equivalent to s^-1, the same as the hertz. The becquerel is usually distinguished from the hertz as an aperiodic unit, whereas the hertz is meant to represent frequency/periodic phenomena.

The becquerel was named for Henri Becquerel in 1975, replacing the unit of the curie, which was defined based on the activity of one gram of radium-226. One becquerel is equivalent to 2.703×10^−11 curie (Ci). Another unit sometimes used it the rutherford, which is equivalent to one megabecquerel. The becquerel is abbreviated as Bq.

Sources/Further Reading: (Wikipedia: Becquerel - Image source; Radioactivity) (Metric System) (Radiation Dosimetry) (EPA)