The fundamental interest in actinide chemistry, particularly for the development of thorium-based materials, is experiencing a renaissance owing to the recent and rapidly growing attention to fuel cycle reactors, radiological daughters for nuclear medicine, and efficient nuclear stockpile development. Herein, we uncover fundamental principles of thorium chemistry on the example of Th-based extended structures such as metal-organic frameworks in comparison with the discrete systems and zirconium extended analogs, demonstrating remarkable over two-and-half-year chemical stability of Th-based frameworks as a function of metal node connectivity, amount of defects, and conformational linker rigidity through comprehensive spectroscopic and crystallographic analysis as well as theoretical modeling. Despite exceptional chemical stability, we report the first example of studies focusing on the reactivity of the most chemically stable Th-based frameworks in comparison with the discrete Th-based systems such as metal-organic complexes and a cage, contrasting multicycle recyclability and selectivity (>97%) of the extended structures in comparison with the molecular compounds. Overall, the presented work not only establishes the conceptual foundation for evaluating the capabilities of Th-based materials but also represents a milestone for their multifaceted future and foreshadows their potential to shape the next era of actinide chemistry.
The dosing interval for effective recombinant adeno-associated virus (rAAV)-mediated gene therapy of cystic fibrosis lung disease remains unknown. Here, we assessed the durability of rAAV2.5T-fCFTRΔR-mediated transgene expression and neutralizing antibody (NAb) responses in lungs of adult wild-type ferrets. Within the first 3 months following rAAV2.5T-fCFTRΔR delivery to the lung, CFTRΔR transgene expression declined â¼5.6-fold and then remained stable to 5 months at â¼26% the level of endogenous CFTR. rAAV NAbs in the plasma and bronchoalveolar lavage fluid (BALF) peaked at 21 days, coinciding with peak ELISpot T cell responses to AAV capsid peptides, after which both responses declined and remained stable at 4-5 months post dosing. Administration of reporter vector rAAV2.5T-gLuc (gaussia luciferase) at 5 months following rAAV2.5T-fCFTRΔR dosing gave rise to similar levels of gLuc expression in the BALF as observed in age-matched reporter-only controls, demonstrating that residual BALF NAbs were functionally insignificant. Notably, the second vector administration led to a 2.6-fold greater ELISpot T cell response and â¼2.3-fold decline in fCFTRΔR mRNA and vector genomes derived from the initial rAAV2.5T-fCFTRΔR administration, suggesting selective destruction of transduced cells from the first vector dose. These findings provide insights into humoral and cellular immune response to rAAV that may be useful for optimizing gene therapy to the cystic fibrosis lung.
OBJECTIVE: There is a lack of strong evidence for use of expensive bone substitutes. This study compares perioperative data and patient reported quality-of-life outcomes across the varied types of bone graft extenders. The study analyzes the existing Quality and Outcomes Database and evaluates patient reported outcomes for 1-3 level lumbar fusion procedures comparing across different types of biologics bone graft. METHODS: We retrospectively analyzed a prospectively collected data registry. Bone graft implant data were collected and grouped into the following categories: (1) Autograft with basic allograft (2) Enhanced, synthetic, or cellular allograft (3) Use of BMP. Preoperative and 1 year patient reported outcomes and perioperative data from the prospective collected registry were analyzed. RESULTS: There were 384 patients included in this study. There were 168 (43.8%) patients in group 1, 133 (34.6%) patients in group 2, and 83 (21.6%) in group 3. There were no group differences in baseline or 1 year back pain, leg pain, ODI, or EQ-5D. The GLM Repeated Measures results indicate a significant difference within each of the three groups between the preoperative and postoperative measures for back pain, leg pain, ODI, and EQ-5D. The change over time was not significantly different between the groups. CONCLUSIONS: Bone graft extenders are a significant contributor to the cost of lumbar fusion. This study demonstrates no difference in preoperative, and 1 year patient reported outcomes between the three groups. There was no significant difference in rate of reoperations across the three groups.
Spinal Fusion , Humans , Retrospective Studies , Treatment Outcome , Prospective Studies , Spinal Fusion/methods , Back Pain/surgery , Lumbar Vertebrae/surgery
The synthesis and structural characterization of the first sulfur-containing derivatives of the C,C-biscarborane {ortho-C2B10}2 cluster - thiol, thioether, and disulfide - are reported. The biscarboranyl dithiol (1-HS-C2B10H10)2 exhibits an exceedingly long intracluster carbon-carbon bond length of 1.858(3) Å, which is attributed to the extensive interaction between the lone pairs of the thiol groups and the unoccupied molecular orbital of the carborane cluster. The structures of the doubly deprotonated biscarboranyl dithiolate anion (1-S-C2B10H10)22- with various counter cations feature an even longer carbon-carbon bond length of 2.062(10) Å within the cluster along with a short carbon-sulfur bond of 1.660(7) Å, both indicative of significant delocalization of electron density from the sulfur atoms into the cluster.
The forthcoming generation of materials, including artificial muscles, recyclable and healable systems, photochromic heterogeneous catalysts, or tailorable supercapacitors, relies on the fundamental concept of rapid switching between two or more discrete forms in the solid state. Herein, we report a breakthrough in the "speed limit" of photochromic molecules on the example of sterically-demanding spiropyran derivatives through their integration within solvent-free confined space, allowing for engineering of the photoresponsive moiety environment and tailoring their photoisomerization rates. The presented conceptual approach realized through construction of the spiropyran environment results in ~1000 times switching enhancement even in the solid state compared to its behavior in solution, setting a record in the field of photochromic compounds. Moreover, integration of two distinct photochromic moieties in the same framework provided access to a dynamic range of rates as well as complementary switching in the material's optical profile, uncovering a previously inaccessible pathway for interstate rapid photoisomerization.
OBJECTIVE: Cervical microendoscopic laminoforaminotomy (MELF) has been proven to be an effective, motion preserving procedure for the surgical treatment of cervical radiculopathy. Cervical 4 (C4) radiculopathies are often unrecognized by the initial evaluating physician and may be misdiagnosed as axial neck pain. In this study, we compare MELF to anterior cervical disk fusion (ACDF) for C4 radiculopathy in the largest series of minimally invasive foraminotomy for C4 radiculopathy to date. METHODS: This is a single-institution retrospective chart review of 42 cases for C4 radiculopathy, 21 MELF and 21 ACDF. Primary outcome measures were length of surgery, length of hospital stay, and time to return to work. Secondary outcome measures were visual analog scale (VAS) neck pain and reoperation rate. RESULTS: All patients were diagnosed with a unilateral C4 radiculopathy using magnetic resonance imaging or steroid injections. The length of surgery and length of hospital stay were significantly decreased in the MELF group compared with ACDF. VAS neck pain significantly decreased for patients in both groups, but the difference between MELF and ACDF was not statistically significant. There were no major complications. No patient underwent revision at the index level or adjacent levels in the MELF group. CONCLUSIONS: We demonstrate that C4 radiculopathy can be identified with appropriate history, physical examination, and targeted nerve root injections. When identified, these radiculopathies that fail conservative therapy can be effectively treated with cervical microendoscopic laminoforaminotomy, with comparable outcomes to ACDF. The length of surgery and length of stay are reduced when compared with ACDF.
Foraminotomy , Radiculopathy , Spinal Diseases , Spinal Fusion , Humans , Radiculopathy/etiology , Radiculopathy/surgery , Neck Pain/etiology , Neck Pain/surgery , Treatment Outcome , Retrospective Studies , Diskectomy/methods , Cervical Vertebrae/diagnostic imaging , Cervical Vertebrae/surgery , Spinal Fusion/methods , Foraminotomy/methods , Spinal Diseases/surgery
A series of transition-metal-containing rare earth thiosilicates, RE3TM0.5SiS7 (RE = Gd-Yb; TM = Fe, Co, Ni), was obtained via flux crystal growth utilizing the boron chalcogen mixture (BCM) method. The series includes the first reported ytterbium-containing thiosilicates crystallizing in this structure type. The thiosilicates crystallize in the hexagonal crystal system in space group P63. The use of the BCM method to synthesize phase-pure samples of the title compounds for magnetic measurements is discussed, highlighting how the approach avoids some of the difficulties that plague typical chalcogenide syntheses. Magnetic measurements demonstrate that some of the compounds order antiferromagnetically and exhibit transition temperatures below 15 K.
We report on a dendronized bis-urea macrocycle 1 self-assembling via a cooperative mechanism into two-dimensional (2D) nanosheets formed solely by alternated urea-urea hydrogen bonding interactions. The pure macrocycle self-assembles in bulk into one-dimensional liquid-crystalline columnar phases. In contrast, its self-assembly mode drastically changes in CHCl3 or tetrachloroethane, leading to 2D hydrogen-bonded networks. Theoretical calculations, complemented by previously reported crystalline structures, indicate that the 2D assembly is formed by a brick-like hydrogen bonding pattern between bis-urea macrocycles. This assembly is promoted by the swelling of the trisdodecyloxyphenyl groups upon solvation, which frustrates, due to steric effects, the formation of the thermodynamically more stable columnar macrocycle stacks. This work proposes a new design strategy to access 2D supramolecular polymers by means of a single non-covalent interaction motif, which is of great interest for materials development.
Geometric magnetic frustration arises when the geometry of a structure prevents the simultaneous fulfillment of nearest-neighbor antiferromagnetic interactions and is commonly observed in lattices that exhibit a triangular topology, such as those found in the pyrochlore structure. Via a mild hydrothermal route, we have synthesized seven quaternary ß-pyrochlore-related fluorides AxM2+xM3+(2-x)F6 (A = Cs and Rb; M2+ = Co2+, Ni2+, and Zn2+; and M3+ = V3+ and Fe3+). Crystal structures and compositions were determined using a combination of single-crystal X-ray diffraction and energy-dispersive spectroscopy. After adjusting the reaction conditions, phase-pure products of AxM2+xM3+(2-x)F6 were obtained. The magnetic susceptibility and isothermal magnetization data for all seven compounds were collected to interpret the magnetic behavior, which ranged from paramagnetic to antiferromagnetic with and without a ferromagnetic component. We found that the magnetic behavior of the AxM2+xV3+(2-x)F6 pyrochlore structures strongly depends on the presence or absence of unpaired electrons on the M2+ position. The titled pyrochlore compounds, with the exception of the Zn-analogue, can be considered frustrated materials, with frustration indices in the range of 6-13.
Mild hydrothermal synthesis was employed to grow high-quality single crystals of ternary fluoridohafnates at low temperatures. The series of new materials was characterized using single-crystal X-ray diffraction, and the crystal structures of AHfF6 (A = Mg and Sr), A2HfF8 (A = Ba and Pb), Ca5Hf3F22, and Cd2HfF8(H2O)6 are discussed herein. Although some material compositions have similar stoichiometries, all of the compositions adopt different structural motifs. A comparison of the crystal structures and synthesis techniques of ternary fluoridohafnates and ternary fluoridozirconates is also reported, and the impact of the subtle changes of synthesis conditions on overall structures is discussed.
Cooperative behavior and orthogonal responses of two classes of coordinatively integrated photochromic molecules towards distinct external stimuli were demonstrated on the first example of a photo-thermo-responsive hierarchical platform. Synergetic and orthogonal responses to temperature and excitation wavelength are achieved by confining the stimuli-responsive moieties within a metal-organic framework (MOF), leading to the preparation of a novel photo-thermo-responsive spiropyran-diarylethene based material. Synergistic behavior of two photoswitches enables the study of stimuli-responsive resonance energy transfer as well as control of the photoinduced charge transfer processes, milestones required to advance optoelectronics development. Spectroscopic studies in combination with theoretical modeling revealed a nonlinear effect on the material electronic structure arising from the coordinative integration of photoresponsive molecules with distinct photoisomerization mechanisms. Thus, the reported work covers multivariable facets of not only fundamental aspects of photoswitch cooperativity, but also provides a pathway to modulate photophysics and electronics of multidimensional functional materials exhibiting thermo-photochromism.
Single crystals of A3MF6 (A = Rb, Cs; M = Al, Ga) were grown from mixed alkali chloride/fluoride fluxes in sealed silver tubes. For Cs3AlF6 and Cs3GaF6, two polymorphs were observed at room temperature: m-Cs3MF6 and o-Cs3MF6. For the two Rb containing compositions, only one room temperature polymorph was observed: o-Rb3AlF6 and t-Rb3GaF6, respectively. Simultaneous TGA/DSC and high temperature SCXRD/PXRD were used to study the high temperature behavior of A3MF6. The compounds of all four compositions were found to undergo structure transitions upon heating to the same cubic structure type, c-A3MF6.
Stabilizing nitrogen pnictogen bond interactions were measured using molecular rotors. Intramolecular C=Oâ â â N interactions were formed in the bond rotation transition states which lowered the rotational barriers and increased the rates of rotation, as measured by EXSY NMR. The pnictogen interaction energies show a very strong correlation with the positive electrostatic potential on nitrogen, which was consistent with a strong electrostatic component. In contrast, the NBO perturbation and pyramidalization analyses show no correlation, suggesting that the orbital-orbital component is minor. The strongest C=Oâ â â N pnictogen interactions were comparable to C=Oâ â â C=O interactions and were stronger than C=Oâ â â Ph interactions, when measured using the same N-phenylimide rotor system. The ability of the nitrogen pnictogen interactions to stabilize transition states and enhance kinetic processes demonstrates their potential in catalysis and reaction design.
Nine new rare earth magnesium-containing thiosilicates of the formula RE3Mg0.5SiS7 (Ln = Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er) were synthesized in an alkali halide flux using the boron chalcogen mixture (BCM) method. Crystals of high quality were produced, and their structures were determined by single-crystal X-ray diffraction. The compounds crystallize in the hexagonal crystal system in the P63 space group. Phase pure powders of the compounds were used for magnetic susceptibility measurements and for second-harmonic generation (SHG) measurements. Magnetic measurements indicate that Ce3Mg0.5SiS7, Sm3Mg0.5SiS7, and Dy3Mg0.5SiS7 exhibit paramagnetic behavior with a negative Weiss temperature over the 2-300 K temperature range. SHG measurements of La3Mg0.5SiS7 demonstrated SHG activity with an efficiency of 0.16 times the standard potassium dihydrogen phosphate (KDP).
Herein, we probe the hydrogen bond-driven self-assembly of a triphenylamine (TPA) bis-urea macrocycle in the presence and absence of guests. Comprised of methylene urea-bridged TPAs with exterior tridodecyloxy benzene solubilizing groups, the macrocycle exhibits concentration-dependent aggregate formation in THF and H2 O/THF mixtures as characterized by 1 Hâ NMR and DOSY experiments. Its assembly processes were further probed by temperature-dependent UV/Vis and fluorescence spectroscopy. Upon heating, UV/Vis spectra exhibit a hypsochromic shift in the λmax , while fluorescence spectra show an increase in emission intensity. Conversely, the protected macrocycle that lacks hydrogen bond donors demonstrates no significant change. Thermodynamic analysis indicates a cooperative self-assembly pathway with distinct nucleation and elongation regimes. The morphology and structure of the aggregate were elucidated by dynamic light scattering, atomic force microscopy, scanning and transmission electron microscopy. Variable temperature emission spectra were utilized to monitor the impact of guests, such as diphenylacetylene, that can be bound in the columnar channels. The findings suggest that the elongation of assemblies is influenced by the presence of these guests. In comparison, diphenyl sulfoxide, likely functioning as a chain stopper, limited the assembly size. These studies suggest that judicious selection of (co)monomers may modulate the function and utility of these supramolecular systems.
BACKGROUND: Ambulatory surgery centers (ASCs) have emerged as an alternative setting for surgical care as part of the national effort to lower health care costs. The literature regarding the safety of minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) in the ASC setting is limited to few small case series. OBJECTIVE: To assess the safety and efficacy of MIS TLIF performed in the ASC vs inpatient hospital setting. METHODS: A total of 775 patients prospectively enrolled in the Quality Outcomes Database undergoing single-level MIS TLIF at a single ASC (100) or the inpatient hospital setting (675) were compared. Propensity matching generated 200 patients for analysis (100 per cohort). Demographic data, resource utilization, patient-reported outcome measures (PROMs), and patient satisfaction were assessed. RESULTS: There were no significant differences regarding baseline demographic data, clinical history, or comorbidities after propensity matching. Only 1 patient required inpatient transfer from the ASC because of intractable pain. All other patients were discharged home within 23 hours of surgery. The rates of 90-day readmission (2.0%) and reoperation (0%) were equivalent between groups. Both groups experienced significant improvements in all PROMs (Oswestry Disability Index, EuroQol-5D, back pain, and leg pain) at 3 months that were maintained at 1 year. PROMs did not differ between groups at any time point. Patient satisfaction was similar between groups at 3 and 12 months after surgery. CONCLUSION: In carefully selected patients, MIS TLIF may be performed safely in the ASC setting with no statistically significant difference in safety or efficacy in comparison with the inpatient setting.
Spinal Fusion , Spondylolisthesis , Humans , Lumbar Vertebrae/surgery , Treatment Outcome , Inpatients , Ambulatory Surgical Procedures/adverse effects , Spondylolisthesis/surgery , Spinal Fusion/adverse effects , Back Pain/surgery , Minimally Invasive Surgical Procedures/adverse effects , Retrospective Studies
Background: Chronic subdural hematoma (CSDH) is primarily a disease of the elderly. Less invasive interventions are often offered for elderly (> 80 years) patients due to concerns for elevated surgical risk, although data suggesting a clear outcome benefit is lacking. Methods: All patients aged 65 years or older who underwent surgical treatment for CSDH at a single institution over a 4-year period were evaluated in this retrospective analysis. Surgical options included twist drill craniostomy (TDC), burr hole craniotomy (BHC), or standard craniotomy (SC). Outcomes, demographics, and clinical data were collected. Practice patterns and outcomes for patients older than 80 years old were compared to the age 65-80 cohort. Results: 110 patients received TDC, 35 received BHC, and 54 received SC. There was no significant difference in post-operative complications, outcomes, or late recurrence (30-90 days). Recurrence at 30 days was significantly higher for TDC (37.3% vs. 2.9% vs 16.7%, p 80 group, SC had higher risk of stroke and increased length of stay. Conclusion: Twist drill craniostomy, burr hole craniostomy, and standard craniotomy have similar neurologic outcomes in elderly patients. Presence of thick membranes is a relative contra-indication for TDC due to high 30-day recurrence. Patients > 80 have higher risk of stroke and increased length of stay with SC.
As part of our exploration of plutonium-containing materials as potential nuclear waste forms, we report the first extended structure Pu(V) material and the first Pu(V) borate. Crystals of Na2(PuO2)(BO3) were grown out of mixed hydroxide/boric acid flux and found to crystallize in the orthorhombic space group Cmcm with lattice parameters of a = 9.9067(4) Å, b = 6.5909(2) Å, and c = 6.9724(2) Å. Na2(PuO2)(BO3) adopts a layered structure in which layers of PuO2(BO3)2- are separated by sodium cations. Plutonium is found in a pentagonal bipyramidal coordination environment, with axial Pu(V)-O plutonyl bond lengths of 1.876(3) Å and equatorial Pu-O bond lengths ranging from 2.325(5) to 2.467(3) Å. We find that the Pu(V)-O plutonyl bond lengths are approximately 0.1 Å longer than the reported Pu(VI)-O plutonyl bond lengths and shorter by approximately 0.033 Å than the corresponding U(V) uranyl bond lengths. Raman spectroscopy on single crystals was used to determine the PuO2+ plutonyl stretching and the equatorial breathing mode frequencies of the pentagonal bipyramidal coordination environment around plutonium. Density functional theory calculations were used to calculate the Raman spectrum to help identify the Raman bands at 690 and 630 cm-1 as corresponding to the plutonyl(V) ν1 stretch and the equatorial PuO5 breathing mode, respectively. UV-vis measurements on single crystals indicate semiconducting behavior with a band gap of â¼2.60 eV.
BACKGROUND: Anterior cervical discectomy and fusion (ACDF) and posterior cervical foraminotomy (PCF) are the most common surgical approaches for medically refractory cervical radiculopathy. Rigorous cost-effectiveness studies comparing ACDF and PCF are lacking. OBJECTIVE: To assess the cost-utility of ACDF vs PCF performed in the ambulatory surgery center setting for Medicare and privately insured patients at 1-year follow-up. METHODS: A total of 323 patients who underwent 1-level ACDF (201) or PCF (122) at a single ambulatory surgery center were compared. Propensity matching generated 110 pairs (220 patients) for analysis. Demographic data, resource utilization, patient-reported outcome measures, and quality-adjusted life-years were assessed. Direct costs (1-year resource use × unit costs based on Medicare national allowable payment amounts) and indirect costs (missed workdays × average US daily wage) were recorded. Incremental cost-effectiveness ratios were calculated. RESULTS: Perioperative safety, 90-day readmission, and 1-year reoperation rates were similar between groups. Both groups experienced significant improvements in all patient-reported outcome measures at 3 months that was maintained at 12 months. The ACDF cohort had a significantly higher preoperative Neck Disability Index and a significantly greater improvement in health-state utility (ie, quality-adjusted life-years gained) at 12 months. ACDF was associated with significantly higher total costs at 1 year for both Medicare ($11 744) and privately insured ($21 228) patients. The incremental cost-effectiveness ratio for ACDF was $184 654 and $333 774 for Medicare and privately insured patients, respectively, reflecting poor cost-utility. CONCLUSION: Single-level ACDF may not be cost-effective in comparison with PCF for surgical management of unilateral cervical radiculopathy.
Foraminotomy , Radiculopathy , Spinal Fusion , United States , Humans , Aged , Cost-Benefit Analysis , Radiculopathy/surgery , Treatment Outcome , Cervical Vertebrae/surgery , Medicare , Diskectomy , Retrospective Studies
OBJECTIVE: Ambulatory surgery centers (ASCs) have become an increasingly attractive setting for spine surgery in recent decades. Although posterior cervical foraminotomy (PCF) is widely performed in ASCs, there are no studies supporting the safety of this practice. We aimed to demonstrate the feasibility and safety of microendoscopic (MED)-PCF in a large cohort of patients at a freestanding ASC. METHODS: Consecutive patients undergoing MED-PCF for unilateral cervical radiculopathy at a single freestanding ASC from January 2013 to December 2020 were queried. Standard demographic and perioperative data were collected. Outcomes included need for inpatient transfer, perioperative complications, 30-day readmission, 30-day reoperation, and clinical improvement according to the Odom criteria. RESULTS: A total of 1106 patients underwent MED-PCF during the study period. Mean age was 53.3 ± 10.3 years. Most patients underwent decompression at C5-6 (31.4%) or C6-7 (51.9%). Approximately 10% underwent surgery at multiple levels. Mean operative time was 40.0 ± 16.4 minutes. There were no intraoperative or immediate postoperative complications. All patients were discharged home within a few hours of surgery. The rates of 30-day readmission (0.81%) and reoperation (0.36%) were exceedingly low. Nearly 3 quarters of patients (73.7%) achieved a good or excellent clinical outcome (73.7%) according to the Odom criteria. CONCLUSIONS: MED-PCF can be performed in a freestanding ASC with exceedingly low rates of perioperative complications and short-term readmission or reoperation. Our findings support the ongoing migration of PCF from the hospital to the ambulatory setting. Future studies assessing patient-reported outcomes and long-term reoperation rates are necessary.
Foraminotomy , Radiculopathy , Humans , Adult , Middle Aged , Ambulatory Surgical Procedures , Feasibility Studies , Treatment Outcome , Cervical Vertebrae/surgery , Radiculopathy/surgery , Retrospective Studies , Diskectomy
