Background/Objectives: The purpose of this study was to develop an activity energy expenditure (AEE) prediction equation for the Actiheart activity monitor for use in children with chronic disease. Subjects/Methods: In total, 63 children, aged 8-18 years with different types of chronic disease (juvenile arthritis, hemophilia, dermatomyositis, neuromuscular disease, cystic fibrosis or congenital heart disease) participated in an activity testing session, which consisted of a resting protocol, working on the computer, sweeping, hallway walking, steps and treadmill walking at three different speeds. During all activities, actual AEE was measured with indirect calorimetry and the participants wore an Actiheart on the chest. Resting EE and resting heart rate were measured during the resting protocol and heart rate above sleep (HRaS) was calculated. Results: Mixed linear modeling produced the following prediction equation:Estimated AEE ðJ=kg= minÞ ¼ À93:7 þ ð4:8ÂHRaSÞþð0:04ÂAccelerometer CountsÞþð39:8ÂGender ðgirls ¼ 0; boys ¼ 1ÞÞ:This equation results in a nonsignificant mean difference of 2.1 J/kg/min (limits of agreement: À144.2 to 148.4 J/kg/min) for the prediction of AEE from the Actiheart compared with actual AEE. Conclusions: The Actiheart is valid for the use of AEE determination when using the new prediction equation for groups of children with chronic disease. However, the prediction error limits the use of the equation in individual subjects.

Magnetic susceptibilities of uranium, plutonium, and neptunium trichlorides, tribomides, and triiodides were measured from 2.7°K to as high as 240°K with a vibrating-sample magnetometer at applied fields up to 12 kOe. Antiferromagnetic transitions were observed in UCl3, TN=22.0±1.0°K; in UBr3, TN=15.0±0.5°K; in UI3, TN=3.4±0.2°K; and in PuCl3, TN=4.5±0.5°K. A ferromagnetic transition at Tc=4.75±0.1°K was found for PuI3, and a slight hysteresis was measured at 2.7°K. Temperature-independent paramagnetism was observed for NpCl3 below 50°K, for α-NpBr3 below 30°K, and for NpI3 below 15°K. All these latter compounds, and PuBr3, exhibited Curie-Weiss paramagnetism at higher temperatures, with effective moments near the free-ion moments. The experimental magnetic susceptibility of PuCl3 from 10 to 100°K agrees with the susceptibility calculated from crystal field energy levels and wavefunctions.

The magnetic susceptibilities of U3+, Np3+, Pu3+, Am3+, Cm3+, and Bk3+ ions in an octahedral environment were measured from 3 to about 50°K with a vibrating-sample magnetometer. Each actinide ion was in a stoichiometric compound of the cubic Cs2NaMCl6 type, except for Cm3+ and Bk3+, which were doped into diamagnetic Cs2NaLuCl6. Curie-Weiss behavior was found for the uranium, neptunium, and plutonium compounds, with evidence for small distortions from octahedral symmetry in the uranium and plutonium compounds. The americium and berkelium samples displayed temperature-independent paramagnetism. For the curium sample, the free-ion moment was observed, but with deviations below 7.5°K that are attributed to crystal-field splitting of Cm3+. The following ground levels were determined: U3+, Γ8; Np3+, Γ5; Pu3+, Γ8; Am3+, Γ1; and Bk3+, Γ1. In Bk3+, a Γ1–Γ4 separation of 85 cm−1 is derived. Limits on the octahedral crystal-field parameters were established from the magnetic data and from crystal-field calculations for U3+ and Np3+, including intermediate coupling and J mixing from the first excited states. From these parameters, the complete crystal-field splitting of each actinide ion in Cs2NaMCl6 was calculated.

Magnetic susceptibility of PaCl4 was measured from 3.2–296°K with a vibrating-sample magnetometer at fields up to 12 000 Oe. PaCl4 has a ferromagnetic transition at Tc=182±2° K. Below Tc the magnetization deviates markedly from Brillouin behavior and is far from saturation at 12 kOe; hysteresis is absent above 3.3°K. A high degree of covalency is suggested to explain the high Curie point; a large anisotropy energy is indicated by the lack of saturation. From 180–210°K, PaCl4 obeys the Curie—Weiss law, χ=C/(T-θ), with θ=157°K and μ eff=1.04 μ B. The measured paramagnetic properties were compared to those calculated from crystal-field theory, with and without J mixing included. The comparison indicates that J mixing is significant in PaCl4.