Rb3MgB5O10 and LiBaAl(BO3)2: covalent tetrahedra MO4-containing borates with deep-ultraviolet cutoff edges.

Borates are favored by materials scientists and chemists because of the significant electronegativity difference between B and O atoms and their flexible assembly modes resulting in abundant structures and excellent properties. For the design of deep-ultraviolet (DUV) optical crystals with excellent macroscopic performance, it is crucial to choose appropriate cations and anionic groups and microscopically reasonable assembly patterns. Herein, by introducing covalent tetrahedra ([MO4], M = Mg, Al), two new mixed alkali metal and alkaline earth metal borates, Rb3MgB5O10 and LiBaAl(BO3)2, were synthesized using the melt method and high-temperature solution method. They contain M-B-O two-dimensional (2D) layers (2∞[MgB5O10] and 2∞[Al(BO3)2], respectively) composed of isolated B-O groups ([B5O10]5- and [BO3]3-, respectively) and metal-centered tetrahedral connectors ([MgO4]6- and [AlO4]5-, respectively). Combining experiments and theoretical calculations shows that the two compounds have short cutoff edges (<200 nm) and moderate birefringences. Further analysis manifests that the isolated [MO4] covalent tetrahedra can optimize the arrangement of anion groups, guarantee the balanced optical properties of materials, and point out the direction for further exploration of novel borate structures.

Surgical treatment for congenital vertebral anomalies with bilateral bifid intrathoracic rib in association: A series of five cases.

Background: Congenital scoliosis is often associated with costal deformities, of which a bilateral bifid intrathoracic rib is very rare. The aim of this study was to retrospectively summarize the clinical manifestations, imaging characteristics, treatment strategies, and postoperative outcomes of five patients with bilateral bifid intrathoracic rib. Methods: We retrospectively reviewed the imaging findings and medical records of five pediatric patients (two girls, three boys) with bilateral bifid intrathoracic rib who were surgically treated for congenital kyphoscoliosis (mean age = 8 years). The clinical manifestations, imaging characteristics, treatment strategies, and postoperative outcome were summarized. Results: Four of five patients showed abnormalities from birth. All five patients presented with kyphoscoliosis and a fused vertebral body or lamina. The bilateral bifid intrathoracic rib was located at T2-3 in three patients, T7 in one patient, and T10 in one patient. Various congenital spinal deformities and multiple system malformations were present in all five patients. Three patients had preoperative neurological deficits. For corrective surgery, one patient received a traditional growing rod implantation, one patient underwent resection of a bony septum, and three patients underwent spinal osteotomy. One patient suffered complete paralysis of the lower limbs after surgery. Conclusion: Bilateral bifid intrathoracic rib is a rare anomaly that typically occurs in patients with serious kyphoscoliosis. Bilateral bifid intrathoracic rib patients show similar clinical and radiological characteristics and are likely to exhibit neurological deficits before or following corrective surgery. Spinal surgeons should be aware of the high risk of permanent neurological complications related to surgery in these patients. Level of evidence: level IV.

Is it necessary to extend fusion to L4 when correcting pediatric L5-S1 spondylolisthesis?

OBJECTIVE: The objective of this study was to investigate whether extending fusion to L4 is imperative in the surgical treatment of pediatric L5-S1 spondylolisthesis. METHODS: This retrospective analysis encompassed 68 pediatric cases of dysplastic L5-S1 spondylolisthesis who underwent posterior lumbar interbody fusion surgery at two hospitals. Patients were categorized into two groups based on the upper instrumented vertebra (group L4 and group L5). Data were collected from medical records and radiological images obtained preoperatively and at last follow-up. Radiographic parameters including slip percentage (SP), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), Spinal Deformity Study Group dysplastic lumbosacral angle (SDSG-LSA), pelvic tilt (PT), Dubousset's lumbosacral angle (Dub-LSA), sacral slope (SS), and severity index (SI) were measured. Surgery-related data and complication data were also collected. The incidence rates of complications were compared, including those of neurological deficit, adjacent-segment instability (ASI), and other complications. ASI was defined as progression of slippage > 3 mm or posterior opening > 5° in the adjacent segment. Clinical outcomes were assessed with the numeric rating scale (NRS) and the Oswestry Disability Index (ODI) scores. The follow-up period for all patients lasted a minimum of 2 years. RESULTS: Among all 68 patients, group L4 consisted of 15 patients and group L5 comprised 53 patients. The patients included in both groups had comparable baseline demographic characteristics and radiographic parameters. Postoperative SP and SDSG-LSA were significantly lower in group L5 (p < 0.05). No other postoperative radiographic differences were observed between groups. One patient in group L4 and 3 patients in group L5 experienced transient neurological deficits (p > 0.05). There were 13 cases of ASI in group L5 compared with none in group L4 (24.5% vs 0%, p > 0.05). Of the 13 patients with ASI, 4 underwent revision surgery due to L4-5 level instability and clinical symptoms. The remaining individuals exhibited no symptoms, and regular annual follow-up assessments are being conducted for all patients. The NRS and ODI scores at final follow-up did not exhibit any significant differences between the two groups. CONCLUSIONS: Fusion to L5 could achieve comparable satisfactory results to fixation to L4, albeit with increased likelihood of ASI. Extension of fusion to L4 may not be necessary for most patients with pediatric L5-S1 spondylolisthesis.

CsAlB3O6Cl: the rational construction of a KBBF-type structure with aligned 2∞[AlB3O6Cl] layers via introducing unprecedented [AlO3Cl] tetrahedra.

The first chloroaluminoborate, CsAlB3O6Cl, with innovative AlO3Cl tetrahedra and a perfect planar arrangement of [B3O6] groups, was structurally designed and synthesized via chlorination of [AlO4] tetrahedra. Simultaneously, the smooth introduction of the [AlO3Cl] group into borates initiates the development of a chloroaluminoborate and greatly enriches the structural chemistry of aluminoborates.