X-ray fluorescence is subject to significant matrix effects, which must be corrected in order to obtain accurate quantitative results. These are due to both absorption and enhancement effects, which are a consequence of the fact that both the analyte and the matrix absorb and fluoresce in the X-ray region, and this affects the magnitude of the…

In this experiment, students explore the synthesis and physical property characterization of the magnetic material strontium hexaferrite (SrFe[subscript 12]O[subscript 19]). SrFe[subscript 12]O[subscript 19] crystallites are prepared by a simple but fascinating sol-gel autocombustion synthesis. The prepared powder is compacted into pellets and…

Here we describe an experiment for the undergraduate physical chemistry laboratory in which students synthesize the intermetallic compounds AlNi and AlNi3 and study them by X-ray diffractometry. The compounds are synthesized in a simple one-step reaction occurring in the solid state. Powder X-ray diffractograms are recorded for the two compounds…

We developed plank test standards, based on trunk lean mass-to-fat mass (LM/FM) ratio, in a sample of healthy Portuguese 10--18 year olds (n = 474, 46.4% female). Height and weight were measured and muscular endurance was assessed using the prone plank test. Trunk LM/FM ratio was determined using dual-energy x-ray absorptiometry. Plank standards…

To understand critical problems associated with solid waste and its consequences for the environment, a laboratory experiment is presented on the synthesis of aluminum-based metal-organic framework (MOF) MIL-53(Al) from household waste (PET bottles and aluminum foil/can), for undergraduate students of chemistry. This work is designed to teach…

Higher relative adiposity is independently associated with adverse health consequences. As such, accurate estimates of body composition in field settings are of utmost importance. The aim of this study was to examine the validity of the Body Adiposity Index (BAI) and Relative Fat Mass (RFM) as measures of total body adiposity. BAI and RFM were…

To examine bone mass in children and adolescents with autism spectrum disorders (ASD). Risperidone-treated 5 to 17 year-old males underwent anthropometric and bone measurements, using dual-energy X-ray absorptiometry and peripheral quantitative computed tomography. Multivariable linear regression analysis models examined whether skeletal outcomes…

Body mass index is a common proxy for proportion of body fat. However, body mass index may not classify youth similarly across ages and ethnicities. We used sex- and ethnic-specific receiver operating characteristic curves to determine how obesity classifications compared between body mass index and dual energy x-ray absorptiometry-based body fat…

As a result of a Department of Defense (DoD) mandate, the U.S. Navy implemented its current body composition assessment (BCA) program in 1982. Despite the feasibility of the current program, its reliability, validity, and applicability have long since been called into question. As a result of these concerns, the Naval Health Research Center (NHRC)…