Improved Birefringence Activated by Tetrahedra Decorated with a Single Linear Unit.

Performance enhancement induced by structural modification has long been the target in materials science fields. Direct evidence to witness the effectivity of one strategy is challenging and necessary. In this work, a tetrahedra-decoration strategy was proposed to improve the birefringent performance sharply, namely decorating the tetrahedra with a single linear [S2 ] unit. The strategy was verified by comprehensive characterization of two thiogermanates K2 BaGeS4 and K2 BaGeS5 , which crystallize in the same space group, have similar unit cells and the same units arrangements. Theoretical characterization verified that the [GeS5 ] group has much larger polarization anisotropy than [GeS4 ], further demonstrated that the linear [S2 ] led to the sharp birefringence enlargement of K2 BaGeS5 (0.19 vs 0.03 of K2 BaGeS4 ). This work provides a new guiding thought to improve the birefringence performance.

Applying formative evaluation in the mentoring of student intern nurses in an emergency department.

Objective: To explore the effectiveness of formative evaluation in the mentoring of student nursing interns in an emergency department. Methods: A total of 144 intern nursing students in the emergency department of a tertiary care hospital in Fuzhou were selected as the study subjects from July 2020 to February 2021. Adopting quasi-experimental studies methods, the students were divided into the experiment group (n = 74) and the control group (n = 70), based on their practicing rotation times. Formative evaluation methods such as in-person interviews, clinical scenario simulations, and clinical operation skills exams were conducted in the experiment group, while traditional summative evaluation methods were adopted for the control group. At the end of the intern period, a unified examination paper on professional knowledge concerning the emergency department, a cardiopulmonary resuscitation skill assessment, and a self-rating scale of self-directed learning was employed to evaluate professional theory performance, clinical practice ability, self-directed learning ability, and academic satisfaction among the nursing students, respectively. Results: The professional theoretical performance, clinical practice ability assessment scores, academic satisfaction, and self-directed learning abilities of the nursing students were significantly higher in the experiment group compared with the control group (P < 0.05). Conclusion: The application of formative evaluation during the mentoring of student intern nurses in an emergency department improved their professional theoretical performance, clinical practice skills, academic satisfaction, and self-directed learning abilities.

AIB3IIC3IIIQ8VI: A New Family for the Design of Infrared Nonlinear Optical Materials by Coupling Octahedra and Tetrahedra Units.

Large second-harmonic generation (SHG) response and broad band gap are two important and competitive parameters. It is difficult to balance them out in one material. In this work, by coupling alkali earth metal (AEM) octahedra with large highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap and nonlinear optical (NLO)-active tetrahedra units, nine noncentrosymmetric (NCS) compounds, belonging to a new quaternary chalcogenide family AIB3IIC3IIIQ8VI with unique windmill-like [Mg3M3IIIQ24] (MIII = Al, Ga; Q = S, Se) units constructed by alternated [MgQ6] octahedra and [MIIIQ4] tetrahedra, are rationally designed and fabricated. The compounds show a stable structural framework but adjustable optical properties. Among them, NaMg3Ga3Se8 shows a large SHG response (∼1 × AgGaS2 (AGS)), wide band gap (in selenide) (2.77 eV), high laser-induced damage threshold (LIDT) (∼2.3 × AGS), and suitable birefringence (0.079@546 nm). It should be a potential candidate for infrared (IR) nonlinear optical (NLO) materials. The results enrich the chemical diversity of chalcogenides and open an avenue for the development of new IR NLO materials through the octahedra and tetrahedra coupled strategy.

Na3YB8O15: a new rare-earth borate with an infinite one-dimensional [B8O15]∞ chain and a short ultraviolet cutoff edge.

A new rare-earth borate Na3YB8O15 was fabricated by the flux method. The compound crystallizes in the P1̄ group, and shows a three-dimensional network built by [B8O17] fundamental building blocks (FBBs) with [NaO6], [NaO7], and [YO7] polyhedra. The [B8O17] FBBs are composed of five planar BO3 and three BO4 tetrahedra and connected via corner-sharing to construct a unique one-dimensional (1D) [B8O15]∞ infinity chain that is observed for the first time in the Na2O-Y2O3-B2O3 system compound, enriching the structural diversity of rare-earth borate. The title compound exhibits a short ultraviolet (UV) cutoff edge of ∼195 nm and a wide experimental band gap of 5.50 eV. DFT calculations indicate that Na3YB8O15 is a direct band gap compound with a calculated GGA band gap of 5.14 eV, and the band gap is mainly determined by B 2p and O 2p orbitals. The results update the phase diagram of Na2O-Y2O3-B2O3 and enrich the diversity of rare-earth metal borates.

NH4IO2F2 and (NH4)3(IO2F2)3·H2O: A Series of Ammonium-Containing Fluoroiodates with Wide Band Gaps.

A series of ammonium-containing fluoroiodates, NH4IO2F2 and (NH4)3(IO2F2)3·H2O, with isolated [IO2F2] units have been fabricated by a fluorine-oxygen substitution strategy from NH4IO3. The two compounds crystallize in the orthorhombic system, but in different space groups, noncentrosymmetric Pca21 for NH4IO2F2 and centrosymmetric Pnma for (NH4)3(IO2F2)3·H2O, and show wide band gaps of 4.53 eV for (NH4IO2F2) and 4.55 eV for ((NH4)3(IO2F2)3·H2O). In addition, NH4IO2F2 exhibits a 1.2 × KDP second harmonic generation response, a short ultraviolet cutoff edge in iodates, and a good crystal growth habit. The crystal of NH4IO2F2 with a size of 11 × 5 × 2 mm3 was obtained by the aqueous solution method. The results enrich the structural diversity of iodate and supply a greater understanding of the design of new functional materials based on the fluoroiodates.

Linear unit BN2: a novel birefringence-enhanced fundamental module with sp orbital hybridization.

Inorganic planar π-conjugated groups are advantageous to generate large birefringence in optical functional materials, and many excellent materials contain CO3, BO3 or B3O6, such as CaCO3, α/ß-BaB2O4 (α/ß-BBO), and KBe2BO3F2 (KBBF). In view of their microscopic structures, the common characteristics are the planar structures, which are regarded as birefringence-enhanced fundamental modules (FMs). Nowadays, exploring novel birefringence-enhanced FMs is becoming a burning issue. Herein, we investigated the birefringence-enhanced FMs in B-N systems and found that the BN2 linear unit could produce great birefringence. Through the investigation based on the Inorganic Crystal Structure Database, some compounds with the BN2 linear group were screened out with the formulas A3BN2 (A = Li, Na), A3BN3 (A = Mg, Ca), and Ba3(BN2)2. Particularly, Ca3(BN2)N exhibits a great birefringence of about 0.411 at 1064 nm, which is 3.5, 2.5 and 2.0 times those of the most commercially used birefringent crystals α-BaB2O4 (Δn = 0.116 at 1064 nm), CaCO3 (Δn = 0.164 at 1064 nm) and YVO4 (Δn = 0.208 at 1064 nm), respectively. To find the origins of the optical properties of compounds with the BN2 linear group, the first-principles, REDA and polarizability anisotropy analysis methods were used. Owing to the structural arrangement and the polarization anisotropy of the BN2 linear group, it can influence the birefringence significantly. This work will provide a general way for exploring birefringence-enhanced FMs in B-N compounds.

Sr3B14O24: a new borate with a [B14O30] fundamental building block and an unwonted 2D double layer.

A new alkaline-earth metal borate, Sr3B14O24, was successfully synthesized by a high-temperature solution method. It crystallizes in the monoclinic space group P21/c (no. 14) and features a fundamental building block (FBB) [B14O30] which is composed of eight [BO3] and six [BO4] units. The FBBs further condense to form an unwonted infinite 2D double layer extended in the bc plane. The UV-Vis-NIR diffuse reflectance spectrum shows that the cutoff edge of Sr3B14O24 is less than 200 nm, which indicates its potential use in the deep UV region. In addition, the first principles theoretical study was carried out to better understand the relationship between the structure and performance.