The Effects of Abdominal Obesity and Sagittal Imbalance on Sacroiliac Joint Pain After Lumbar Fusion.

BACKGROUND: Postoperative sacroiliac joint pain (SIJP) is a common manifestation of failed back surgery syndrome after a posterior lumbar interbody fusion (PLIF). However, there is currently no consensus on the risk factors for SIJP after PLIF. OBJECTIVES: We explored the effects of abdominal obesity and sagittal imbalance on SIJP after PLIF. STUDY DESIGN: This is a prospective observational cohort study. SETTING: This study occurred at the Department of Spinal Surgery at a hospital affiliated with a medical university. METHODS: A total of 401 patients who underwent PLIF from June 2018 to June 2021 were enrolled in this study. 36 patients experienced postoperative SIJP. In contrast, a matched group comprised 72 non-SIJP patients. We used 1:2 propensity score matching to compare obesity features and sagittal spine parameters in the 2 groups. Inflammatory cytokines and visual analog scale (VAS) scores were measured in the SIJP group. RESULTS: A total of 36 patients (8.98%) experienced SIJP during the follow-up. Compared with the non-SIJP group, patients with postoperative SIJP had a higher body mass index (BMI), greater abdominal obesity, a higher incidence of pelvic incidence-lumbar lordosis greater than 10°, and a higher incidence of a sagittal vertical axis greater than 5 cm (P < 0.05). Receiver operating characteristic curve analysis showed that the area under the curve for waist circumference was greater than that for BMI (0.762 vs. 0.650, P = 0.049). Logistic regression analysis revealed that the risk factors for SIJP were abdominal obesity, a pelvic incidence-lumbar lordosis of greater than 10°, and a sagittal vertical axis greater than 5 cm (P < 0.05). In patients with SIJP, interleukin 6, tumor necrosis factor-α, and VAS scores were higher in the abdominal obesity group than in the non-abdominal obesity group (P < 0.05). LIMITATIONS: There was no uniform diagnosis of SIJP, so the incidence rate of SIJP might not be accurate. CONCLUSIONS: The significant predictors of SIJP were abdominal obesity and sagittal imbalance. Patients with abdominal obesity showed higher levels of inflammatory markers and pain intensity. More attention should be paid to body shape and the angle of correction of lumbar lordosis before lumbar surgery.

Enhancing Aqueous Chlorate Reduction Using Vanadium Redox Cycles and pH Control.

Chlorate (ClO3-) is a toxic oxyanion pollutant from industrial wastes, agricultural applications, drinking water disinfection, and wastewater treatment. Catalytic reduction of ClO3- using palladium (Pd) nanoparticle catalysts exhibited sluggish kinetics. This work demonstrates an 18-fold activity enhancement by integrating earth-abundant vanadium (V) into the common Pd/C catalyst. X-ray photoelectron spectroscopy and electrochemical studies indicated that VV and VIV precursors are reduced to VIII in the aqueous phase (rather than immobilized on the carbon support) by Pd-activated H2. The VIII/IV redox cycle is the predominant mechanism for the ClO3- reduction. Further reduction of chlorine intermediates to Cl- could proceed via VIII/IV and VIV/V redox cycles or direct reduction by Pd/C. To capture the potentially toxic V metal from the treated solution, we adjusted the pH from 3 to 8 after the reaction, which completely immobilized VIII onto Pd/C for catalyst recycling. The enhanced performance of reductive catalysis using a Group 5 metal adds to the diversity of transition metals (e.g., Cr, Mo, Re, Fe, and Ru in Groups 6-8) for water pollutant treatment via various unique mechanisms.

Microbial Defluorination of Unsaturated Per- and Polyfluorinated Carboxylic Acids under Anaerobic and Aerobic Conditions: A Structure Specificity Study.

The recently discovered microbial reductive defluorination of two C6 branched and unsaturated fluorinated carboxylic acids (FCAs) provided valuable insights into the environmental fate of per- and polyfluoroalkyl substances (PFASs) and potential bioremediation strategies. However, a systematic investigation is needed to further demonstrate the role of C═C double bonds in the biodegradability of unsaturated PFASs. Here, we examined the structure-biodegradability relationships of 13 FCAs, including nine commercially available unsaturated FCAs and four structurally similar saturated ones, in an anaerobic defluorinating enrichment and an activated sludge community. The anaerobic and aerobic transformation/defluorination pathways were elucidated. The results showed that under anaerobic conditions, the α,ß-unsaturation is crucial for FCA biotransformation via reductive defluorination and/or hydrogenation pathways. With sp2 C-F bonds being substituted by C-H bonds, the reductive defluorination became less favorable than hydrogenation. Moreover, for the first time, we reported enhanced degradability and defluorination capability of specific unsaturated FCA structures with trifluoromethyl (-CF3) branches at the α/ß-carbon. Such FCA structures can undergo anaerobic abiotic defluorination in the presence of reducing agents and significant aerobic microbial defluorination. Given the diverse applications and emerging concerns of fluorochemicals, this work not only advances the fundamental understanding of the fate of unsaturated PFASs in natural and engineered environments but also may provide insights into the design of readily degradable fluorinated alternatives to existing PFAS compounds.

Electrocatalytic Perchlorate Reduction Using an Oxorhenium Complex Supported on a Ti4O7 Reactive Electrochemical Membrane.

An organometallic rhenium catalyst was deposited on a Ti4O7 reactive electrochemical membrane (Re/REM) for the electrocatalytic reduction of aqueous ClO4- to Cl-. Results showed increasing ClO4- reduction upon increasing cathodic potential (i.e., -0.4 to-1.7 V/SHE). A 5 mM ClO4- solution was reduced by ∼21% in a single pass (residence time ∼0.2 s) through the Re/REM at a pH of 7, with >99% Cl- selectivity and a current efficiency of ∼100%. Kinetic analysis indicated that the reaction rate constant increased from 3953 to 7128 L h-1 gRe-1 at pH values of 9 to 3, respectively, and was mass transport-limited at pH < 5. The rate constants were 2 orders of magnitude greater than reported values for an analogous catalytic system using hydrogen as an electron donor. A continuous flow Re/REM system reduced 1 ppm ClO4- in a groundwater sample by >99.9% for the first 93.5 h, and concentrations were lower than the EPA ClO4- guideline (56 ppb) for 374 h of treatment. The fast ClO4- reduction kinetics and high chloride selectivity without the need for acidic conditions and a continual hydrogen electron donor supply for catalyst regeneration indicate the promising ability of the Re/REM for aqueous electrocatalytic ClO4- treatment.

Near-Quantitative Defluorination of Perfluorinated and Fluorotelomer Carboxylates and Sulfonates with Integrated Oxidation and Reduction.

The UV-sulfite reductive treatment using hydrated electrons (eaq-) is a promising technology for destroying perfluorocarboxylates (PFCAs, CnF2n+1COO-) in any chain length. However, the C-H bonds formed in the transformation products strengthen the residual C-F bonds and thus prevent complete defluorination. Reductive treatments of fluorotelomer carboxylates (FTCAs, CnF2n+1-CH2CH2-COO-) and sulfonates (FTSAs, CnF2n+1-CH2CH2-SO3-) are also sluggish because the ethylene linker separates the fluoroalkyl chain from the end functional group. In this work, we used oxidation (Ox) with hydroxyl radicals (HO•) to convert FTCAs and FTSAs to a mixture of PFCAs. This process also cleaved 35-95% of C-F bonds depending on the fluoroalkyl chain length. We probed the stoichiometry and mechanism for the oxidative defluorination of fluorotelomers. The subsequent reduction (Red) with UV-sulfite achieved deep defluorination of the PFCA mixture for up to 90%. The following use of HO• to oxidize the H-rich residues led to the cleavage of the remaining C-F bonds. We examined the efficacy of integrated oxidative and reductive treatment of n = 1-8 PFCAs, n = 4,6,8 perfluorosulfonates (PFSAs, CnF2n+1-SO3-), n = 1-8 FTCAs, and n = 4,6,8 FTSAs. A majority of structures yielded near-quantitative overall defluorination (97-103%), except for n = 7,8 fluorotelomers (85-89%), n = 4 PFSA (94%), and n = 4 FTSA (93%). The results show the feasibility of complete defluorination of legacy PFAS pollutants and will advance both remediation technology design and water sample analysis.

A Bioinspired Molybdenum Catalyst for Aqueous Perchlorate Reduction.

Perchlorate (ClO4-) is a pervasive, harmful, and inert anion on both Earth and Mars. Current technologies for ClO4- reduction entail either harsh conditions or multicomponent enzymatic processes. Herein, we report a heterogeneous (L)Mo-Pd/C catalyst directly prepared from Na2MoO4, a bidentate nitrogen ligand (L), and Pd/C to reduce aqueous ClO4- into Cl- with 1 atm of H2 at room temperature. A suite of instrument characterizations and probing reactions suggest that the MoVI precursor and L at the optimal 1:1 ratio are transformed in situ into oligomeric MoIV active sites at the carbon-water interface. For each Mo site, the initial turnover frequency (TOF0) for oxygen atom transfer from ClOx- substrates reached 165 h-1. The turnover number (TON) reached 3840 after a single batch reduction of 100 mM ClO4-. This study provides a water-compatible, efficient, and robust catalyst to degrade and utilize ClO4- for water purification and space exploration.

Microbial Cleavage of C-F Bonds in Two C6 Per- and Polyfluorinated Compounds via Reductive Defluorination.

The C-F bond is one of the strongest single bonds in nature. Although microbial reductive dehalogenation is well known for the other organohalides, no microbial reductive defluorination has been documented for perfluorinated compounds except for a single, nonreproducible study on trifluoroacetate. Here, we report on C-F bond cleavage in two C6 per- and polyfluorinated compounds via reductive defluorination by an organohalide-respiring microbial community. The reductive defluorination was demonstrated by the release of F- and the formation of the corresponding product when lactate was the electron donor, and the fluorinated compound was the sole electron acceptor. The major dechlorinating species in the seed culture, Dehalococcoides, were not responsible for the defluorination as no growth of Dehalococcoides or active expression of Dehalococcoides-reductive dehalogenases was observed. It suggests that minor phylogenetic groups in the community might be responsible for the reductive defluorination. These findings expand our fundamental knowledge of microbial reductive dehalogenation and warrant further studies on the enrichment, identification, and isolation of responsible microorganisms and enzymes. Given the wide use and emerging concerns of fluorinated organics (e.g., per- and polyfluoroalkyl substances), particularly the perfluorinated ones, the discovery of microbial defluorination under common anaerobic conditions may provide valuable insights into the environmental fate and potential bioremediation strategies of these notorious contaminants.

Degradation of nitrilotris-methylenephosphonic acid (NTMP) antiscalant via persulfate photolysis: Implications on desalination concentrate treatment.

Nitrilotris-methylenephosphonic acid (NTMP) has been widely used as an antiscalant in reverse osmosis (RO) desalination and other industrial processes to inhibit scaling from calcium and other hardness ions. Removal of NTMP from RO concentrate can induce the precipitation of oversaturated scale-forming substances, enable additional water recovery from RO concentrate, and reduce the risk of eutrophication after brine disposal. This study investigated the kinetics and mechanisms of oxidative degradation of NTMP by UV photolysis of persulfate at 254 nm. Results showed that NTMP was effectively degraded by persulfate photolysis and the reaction followed pseudo first-order kinetics. The degradation of NTMP was favorable at circumneutral pHs but significantly inhibited in highly alkaline conditions (e.g., pH of 11.5), mainly due to the reduced concentration of SO4•-. Using a competition reaction kinetics approach, the second-order rate constants of NTMP with SO4•- and HO• were determined to be (2.9 ±â€¯0.6) × 107 M-1s-1 and (1.1 ±â€¯0.1) × 108 M-1s-1, respectively. SO4•- had a predominant contribution to NTMP degradation (62%-95%), because the steady-state concentration of SO4•- was 11-54 times higher than that of HO• at pHs between 4 and 11.5. NTMP degradation rate increased with an increase in persulfate dosage and a decrease in NTMP concentration. In the real RO concentrate, NTMP degradation rate was impacted by the presence of chloride and bicarbonate. The degradation of NTMP started with the cleavage of C-N bonds, and then generated intermediates including iminodi(methylene)phosphonate, hydroxymethylphosphonic acid and aminotris(methylenephosphonic acid), which were eventually mineralized into ammonia, phosphate and carbon dioxide. This study demonstrated that UV/persulfate is a promising technology to remove phosphonate antiscalants from RO concentrate.