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Background: Mild traumatic brain injury (mTBI) causes a number of molecular and cellular alterations. There is evidence of an imbalance between the main excitatory (glutamate, Glu) and the main inhibitory (gamma‐aminobutyric acid [GABA]) neurotransmitters following mTBI. In vivo human GABA–Glu balance studies following mTBI are sparse. Purpose: To investigate the effect of acute mTBI on the GABA concentration measured in the posterior cingulate cortex (PCC) of pediatric patients by using the macromolecular (MM)‐suppressed GABA J‐editing technique. Study type: Prospective patient and phantom. Participants: A total of 14 pediatric patients (mean age 16.0 ± 1.7) with acute mTBI (<3 days after trauma; Glasgow Coma Scale 15) and 16 healthy volunteers (mean age 16.9 ± 2.8). Phantom: 524 cm3 sphere containing 10 mM glycine, 10 mM GABA. Field Strength/Sequence: A 3 T, MEGA‐PRESS pulse sequence. Assessment: GABA spectra were processed in Gannet software. MM‐suppressed GABA editing efficiency was derived from the phantom study. Absolute GABA and glutamate + glutamine (Glx) concentrations were quantified using different types of correction and compared between groups. N‐acetyl aspartate (NAA) and choline (Cho) levels relative to tCr were also compared. Statistical tests: Shapiro–Wilk test, Mann–Whitney U test, Student t‐test, Pearson or Spearman correlations. P < 0.01 was considered statistically significant. Results: The MM‐suppressed GABA editing efficiency was 0.63. GABA signal fit error was <16% for all participants. The GABA concentration in the PCC of the mTBI group was significantly different from that in healthy controls: GABA/tCr was higher by 27%, absolute GABA concentration with different types of correction was higher by ≈17%. No significant differences were observed in Glx concentrations (P ≥ 0.32) or in Glx/tCr (P ≥ 0.1), NAA/tCr (P = 0.55), and Cho/tCr levels (P = 0.85). Data conclusion: We report an increase in the GABA concentration in the PCC region in acute mTBI pediatric patients. This may suggest activation of GABA synthesis and impairment of the GABAergic system after acute mTBI. Evidence Level: 3 Technical Efficacy: Stage 1 [ABSTRACT FROM AUTHOR]

Broadband near‐infrared (NIR) luminescent materials have received notable attention due to their distinct photophysical properties for designing NIR light‐emitting diodes (NIR LEDs). Here, a series of Ca3−xLuxGa2+xGe3−xO12:Cr3+ (CLGGG:Cr3+) (x = 0–1) NIR‐emitting garnet phosphors with an emission range of 660–1200 nm are successfully developed and their lattice parameters are structurally analyzed. Upon 460 nm blue light excitation, the NIR phosphors exhibit both a substantial spectral broadening (FWHM: 129→267 nm) and a redshift of 37 nm (766→803 nm) with cosubstitution of [Lu3+–Ga3+] pairs for [Ca2+–Ge4+] sites. Furthermore, their luminescence thermal stability is substantially improved, maintaining ≈90% of the original photoluminescence intensity at 150 °C, owing to shrinkage of the second coordination sphere and rigid lattice, which are strongly associated with Cr3+ trade‐off occupancy and local structure evolutions. The relation between the trade‐off site occupation of Cr3+ in GaO6/CaO8 polyhedrons and the NIR emission is also clarified by evaluating the decay and electron paramagnetic resonance behavior of Cr3+ at different sites. The broadband NIR phosphors investigated here can serve as auspicious luminescent converters for phosphor‐converted NIR LEDs and can provide an inspiring platform for future studies. [ABSTRACT FROM AUTHOR]

As a luminous center, Mn2+ has the advantages of high efficiency, safety, and low cost, and has been widely used to improve the color rendering index of garnet structured phosphors. Although the position of Mn2+ in garnet structures and its corresponding spectrum have been widely discussed, there is no convincing conclusion. In this paper, the selectivity of Mn2+ ion occupancy in the Y3Al5O12:0.1Ce3+,yMn2+ (y = 0–0.22) garnet structure and their corresponding emission spectra were determined. At low substitution density, Mn2+ ions (y = 0–0.007) easily replace Al3+ ions in the octahedron and emit 590 nm red light under 450 nm blue light excitation, which were determined by calculating the formation energy of the (Mn/Al) and (Mn/Y) local coordination and powder XRD analysis. Upon increasing the Mn2+ concentration from 0.007 to 0.22, the emission light with a peak at 750 nm gradually appears. Meanwhile, the effect of Y3+ ions on the energy transfer of Ce3+ → Mn2+ in (Lu1−xYx)3Al4.8Si0.2O12:0.1Ce3+,0.2Mn2+ (x = 0–1) is achieved through the reduction of the distance between Ce3+ and Mn2+ ions in the dodecahedron. The above work provides support for the correct understanding of the luminescence behavior of Mn2+, and the influence of the microstructure on the energy transfer of Ce3+ → Mn2+ ions. Finally, high color rendering index (83.4) wLEDs were fabricated by the Lu1.2Y1.8Al4.8Si0.2O12:0.1Ce3+,0.2Mn2+ phosphor and the blue chip under 120 mA. [ABSTRACT FROM AUTHOR]

(Tb 1- x Mn x ) 3 Al 2 (Al 1- x Si x ) 3 O 12 :Ce 3+ solid solution phosphors were synthesized by introducing the isostructural Mn 3 Al 2 (SiO 4 ) 3 (MAS) into Tb 3 Al 5 O 12 :Ce 3+ (TbAG). Under 456 nm excitation, (Tb 1- x Mn x ) 3 Al 2 (Al 1- x Si x ) 3 O 12 :Ce 3+ shows energy transfers (ET) in the host, which can be obtained from the red emission components to enhance color rendering. Moreover, (Tb 1- x Mn x ) 3 Al 2 (Al 1- x Si x ) 3 O 12 :Ce 3+ ( x = 0-0.2) exhibits substantial spectral broadening (68 → 86 nm) due to the 5d → 4f transition of Ce 3+ and the 4 T 1 → 6 A 1 transition of Mn 2+ . The efficiency of energy transfer ( η T , Ce 3+ → Mn 2+ ) gradually increases with increasing Mn 2+ content, and the value reach approximately 32% at x = 0.2. Namely, the different characteristics of luminescence evolution based on the effect of structural variation by substituting the (MnSi) 6+ pair for the larger (TbAl) 6+ pair. Therefore, with structural evolution, the luminescence of the solid solution phosphors could be tuned from yellow to orange-red, tunable by increasing the content of MAS for the applications of white light emitting diodes (wLED)., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)