Nonresonant Polarized Raman Spectra Calculations of Nitrogen-Doped Single-Walled Carbon Nanotubes: Diameter, Chirality, and Doping Concentration Effects.

Raman spectra of nitrogen-doped single-walled carbon nanotubes are calculated using the spectral moment's method combined with the bond polarizability model. The influence of the nanotube diameter and chirality is investigated. We also address the important question of the effect of the N-doping concentration, and we propose an equation to estimate the doping concentration from the knowledge of the tube diameter and the frequency of the radial breathing mode.

Risk of noncommunicable diseases and associated factors in Algerian adolescents (10-19 years old).

OBJECTIVE: Noncommunicable diseases (NCDs) are a public health problem and their prevalence is increasing worldwide at an alarming rate. The objective of this study was to assess the predictive factors for NCDs in adolescents. MATERIAL AND METHODS: The study included adolescents enrolled in public establishments in Constantine (east of Algeria). Demographic variables, health variables, smoking, anthropometry, diet, and physical activity were assessed by means of a questionnaire. All data were analyzed using the software R 3.2.4. The significance threshold was set at 95%. RESULTS: The sample consisted of 1,222 adolescents (56.1% girls) aged 10-19 years. Overall, 8.6% had NCDs; 23.2% were overweight (obesity included). The frequency of consumption was insufficient for dairy products and fruits and vegetables (p=0.0000) and the opposite was found for fatty and sugary products (p=0.0000). A total of 82.8% had been breastfed. Physical activity recommendations were not followed. Risk factors for the development of NCDs were family history of these diseases (odds ratio [OR]=2.89), active smoking (OR=3.18), passive smoking (OR=2.03), fetal macrosomia (OR=1.40), time in front of screens ≥3 h/day (OR=1.28), and overweight (OR=1.15). The consumption of fatty and sweet products was positively correlated with weight status (r=0.258; p=0.0000). Protective factors were breastfeeding for ≥ 6 months (OR=0.69) and moderate physical activity of ≥60 min/day (OR=0.38). CONCLUSION: Adolescents presented predictors factors for NCDs due to harmful behaviors to their health.

Computation of the infrared active modes in single-walled boron nitride nanotube bundles.

In this work, the infrared active modes are computed for homogeneous bundles of single-walled boron nitride nanotubes (BBNNTs), using the so-called spectral moments method. The dependence of the wavenumber on these modes in terms of diameters, lengths, and numbers of tubes, is investigated. To this end, use is made of a Lennard-Jones potential for describing the van der Waals interactions between tubes in a bundle. We find that, for a finite homogeneous bundle, additional modes appear as a specific signature. Finally, these results are useful for the interpretation of the experimental infrared spectra of BBNNTs.