A common thalamic hub for general and defensive arousal control.

The expression of defensive responses to alerting sensory cues requires both general arousal and a specific arousal state associated with defensive emotions. However, it remains unclear whether these two forms of arousal can be regulated by common brain regions. We discovered that the medial sector of the auditory thalamus (ATm) in mice is a thalamic hub controlling both general and defensive arousal. The spontaneous activity of VGluT2-expressing ATm (ATmVGluT2+) neurons was correlated with and causally contributed to wakefulness. In sleeping mice, sustained ATmVGluT2+ population responses were predictive of sensory-induced arousal, the likelihood of which was markedly decreased by inhibiting ATmVGluT2+ neurons or multiple downstream pathways. In awake mice, ATmVGluT2+ activation led to heightened arousal accompanied by excessive anxiety and avoidance behavior. Notably, blocking their neurotransmission abolished alerting stimuli-induced defensive behaviors. These findings may shed light on the comorbidity of sleep disturbances and abnormal sensory sensitivity in specific brain disorders.

Luminescence properties and energy transfer of the near-infrared phosphor Ca3In2Ge3O12:Cr3+,Nd3.

The double doping strategy based on energy transfer is an effective way to regulate the NIR spectral distribution. In this work, Ca3In2Ge3O12:xNd3+ (CIG:xNd3+) and Ca3-x In1.93Ge3O12:0.07Cr3+,yNd3+ (CIG:0.07Cr3+,yNd3+) phosphors are successfully prepared via a high-temperature solid-state method. CIG:0.07Cr3+ shows broadband emission centered at 804 nm, which covers most of the excitation peaks of Nd3+ ions. Under excitation at 480 nm, Cr3+ can provide effective energy transfer to Nd3+. In addition, CIG:0.07Cr3+,0.15Nd3+ has good temperature stability, and maintains 68.98% of the room-temperature intensity at 150 °C. The phosphors can convert short-wave photons to long-wave photons and enhance solar cell utilization, demonstrating the potential application of this material in solar spectral conversion technology.

Achieving the potential multifunctional near-infrared materials Ca3In2-x Ga x Ge3O12:Cr3+ using a solid state method.

Near-infrared spectroscopy is developing rapidly in the fields of human detection and food analysis due to its fast response and non-invasive characteristics. Herein, we report the novel near-infrared garnet-type Ca3In2Ge3O12:xCr3+ and Ca3In2-x Ga x Ge3O12:0.07Cr3+ phosphors, in which there are two crystallographic sites (CaO8, InO6) that can be substituted by Cr3+, and cation regulation engineering for In3+ is utilized to tune the luminescence properties. Under the 480 nm excitation, the Ca3In2Ge3O12:xCr3+ phosphor emits a broad spectrum at 650-1150 nm, which matches well with the first biological window. The concentration quenching mechanism and luminescence mechanism of Ca3In2Ge3O12:xCr3+ were studied and the site assignment of the two luminescence centers was discussed using low temperature spectra and fluorescence decay curves. The application performance of the phosphor was improved by introducing Ga3+ to substitute for In3+, and the blue shift of nearly 50 nm was explained by crystal field and nephelauxetic effects. At the same time, a 24% increase in the activation energy of thermal quenching of phosphors was obtained, which has been analyzed using the mechanism of phonon transition and the change of structural rigidity. Thus, the near-infrared emitting Ca3In0.2Ga1.8Ge3O12:0.07Cr3+ phosphor was obtained, which has lower cost, higher emission intensity, and much better thermal stability, spreading the application of phosphors in plant far red light illumination, human body detection, and spectral conversion technology of silicon-based solar cells. Simultaneously, an example of a near-infrared plant illumination experiment is given, demonstrating that a cation substitution strategy based on crystal field control could be applied to tune spectral distribution and develop novel potential phosphors for practical optical application.

Achievement of narrow-band blue-emitting phosphors KScSr1-y Ca y Si2O7:Bi3+ by the migration of luminescence centers.

In recent years, efforts have been made to develop narrow-band emission phosphors with excellent performance. Herein, a series of KScSr1-y Ca y Si2O7:0.07Bi3+ narrow-band phosphors were synthesized by a co-substitution method, and the crystal structure, the occupancy of activated ions and luminescence properties were studied in detail. The substitution of Ca2+ for Sr2+ ions resulted in the migration of the activated Bi3+ from the K site to Sr site, accompanied by the regulation of the emission peak from 410 nm to 455 nm, the peak emission half width from 52 nm to 40 nm, and the color purity from the original 78% to 88%. In addition, a warm white LED with low CCT = 3401 K, CRI = 95.5, and CIE color coordinates of (0.3447, 0.3682) has been obtained through the combination of KSS0.6C0.4S:0.07Bi3+ with a commercial green and red phosphor on a UV (370 nm) chip. The results not only provided a strategy based on the manipulation of chemical composition and crystal structure to tune spectral distribution, but also broadens the choice of activators of narrow-band blue-emitting phosphors.

Recent progress of effect of crystal structure on luminescence properties of Ce3+-Eu2+ Co-doped phosphors.

Currently, the mechanism of Ce3+-Eu2+ ET is frequently used to obtain color adjustable or white phosphors. Correspondingly, the ET efficiency from Ce3+ to Eu2+ becomes an important indication of the luminescent properties of phosphors. However, the ET efficiency calculated using the formula does not always match the emission spectra; the transmission efficiency of Ce3+ is high, but the emission efficiency of Eu2+ is low, depending on our investigation results. In addition to this problem, here we mainly review, on the basis of substantial examples, how to boost the actual ET efficiency of Ce3+-to-Eu2+ and thus to improve the luminescent properties of phosphors through the rational design of layered crystal structure and the way of selective occupation of activator ions. Moreover, the possible physical mechanisms are proposed.

A dual-excited and dual near-infrared emission phosphor Mg14Ge5O24:Cr3+,Cr4+ with a super broad band for biological detection.

Recently, near-infrared phosphors that can be applied in many fields such as night vision, agriculture, and bio-applications have attracted considerable interest in the research field worldwide. Herein, a multi-functional and dual-excited near-infrared phosphor Mg14Ge5O24:Cr3+,Cr4+ which provides two emission bands ranging from 700 nm to 1100 nm and 1100 nm to 1700 nm has been obtained via the traditional high-temperature solid state reaction. The presence of six and four coordination ions in the olivine structure of Mg14Ge5O24 provides a favorable environment for the coexistence of Cr3+ and Cr4+. Under blue light excitation, a super broad emission band ranging from 650 nm to 1100 nm with a full-width at half maximum (FWHM) of 266 nm is assigned to the spin-allowed 4T2 (4F) →4A2 transition of Cr3+ in a weak crystal-field environment. With the increase in the concentration of Cr ions, more and more Cr4+ preferentially occupies four coordinated Ge4+ sites, and the other broad emission band ranging from 1100 nm to 1600 nm with a FWHM of 256 nm that comes from the 3T2→3A2 transition of Cr4+ is observed. The phenomenon of NIR I region excitation and NIR II region emission appears. The transmission experiment of a biological tissue proves that the Mg14Ge5O24:Cr3+,Cr4+ phosphor has potential applications in the field of near-infrared light-emitting diodes for biological detection.