Combined Strategies Enable Highly Selective Light Olefins and para-Xylene Production on Single Catalyst Bed.

Achieving multiple high-value-added chemical production through novel reaction processes and shape-selective catalytic strategy is the key to realizing efficient low-carbon catalytic processes. In this work, a methanol-toluene coreaction system was developed, and combined control strategies of reaction pathway guidance and shape-selective catalysis were applied for the successful production of light olefins and para-xylene on single HZSM-5 catalyst bed. Cofeeding toluene additionally provides reactive and flowing aromatic hydrocarbon pool species that change the dominant reaction pathway in the complex network of the methanol reaction on HZSM-5 and promote the formation of ethylene. For the first time, the key reaction intermediates methylmethylenecyclodiene are directly captured and identified by experimental and theoretical techniques. This helps to propose the catalytic cycle for the dominant generation of ethylene and, more importantly, enriches the methanol-to-hydrocarbons (MTH) chemistry and hydrocarbon pool mechanism. Furthermore, 0.4HZSM-5@S-1-CLD, an optimized HZSM-5 catalyst modified by the silicalite-1 epitaxial growth followed by silanization approach, realizes highly selective production of light olefins (especially ethylene) and para-xylene, while excellent reactant activity is maintained. This highly efficient coreaction route gives an important leading significance in synthesizing the raw materials for the polyolefin and polyester industries. The establishment of the combined control strategies provides a model for the joint production of multiple target chemicals in complex catalytic processes.

Accuracy and digital screw path design of TiRobot-assisted pedicle screw placement for lumbar spondylolisthesis.

PURPOSE: To investigate lumbar spondylolisthesis screw placement assisted by TiRobot in terms of digital screw path design, accurate implementation, and accuracy evaluation method. METHODS: In this study, we enrolled 40 patients with lumbar spondylolisthesis between December 2020 and August 2021 who underwent spine surgery at the Affiliated Hospital of PuTian University. Pre-operative computed tomography position and screw path designation, intra-operative pedicle screw placement according to pre-operative planning, and post-operative evaluation of the accuracy of screw placement were performed. 3D coordinates of the entry and exit points before and after the operation were collected. The qualified points at different levels of accuracy were counted. The screw placement accuracy was based on the absolute difference using the Chi-squared test. RESULTS: In total, 194 screws were successfully implanted with no screws penetrating the cortex. The absolute difference of entry points X, Y, and Z coordinates before and after the operation was 0.425 ± 0.294 mm, 0.417 ± 0.310 mm, and 0.466 ± 0.327 mm, respectively. The corresponding values in terms of exit points were 0.702 ± 0.470 mm, 0.963 ± 0.595mm, and 0.983 ± 0.566 mm, respectively. No obvious differences in coordinates before and after the operation were observed with an entry point degree of accuracy of ≥ 1.2 mm and exit point degree of accuracy of ≥ 2.1 mm. Therefore, the real surgery was consistent with the design. CONCLUSIONS: TiRobot-assisted lumbar spondylolisthesis surgery achieved optimal path designation and precise surgery.

Dynamic Evolution of Aluminum Coordination Environments in Mordenite Zeolite and Their Role in the Dimethyl Ether (DME) Carbonylation Reaction.

Part of tetrahedral framework aluminum in a protonic mordenite (HMOR) will convert geometry to distorted tetrahedral and octahedral coordination. High-field 27 Al NMR data show that more framework Al atoms at T3 and T4 sites change geometry to nonframework structures than others. These nonframework Al species preferentially reside in the side pockets, which will decrease the accessibility of acid sites in the 8-membered ring (MR) channel, impairing the dimethyl ether (DME) carbonylation reaction. The arisen octahedrally coordinated Al species are framework-associated, which can be reverted into the zeolite framework. Herein, we find that a facile treatment with pyridine could force the octahedral coordination Al back into a tetrahedral environment, which could increase the number of available active sites and enhance the diffusion of DME, thus improving the reactivity (4 times) of the DME carbonylation reaction and prolonging the lifetime of catalysts.

Increasing the Number of Aluminum Atoms in T3 Sites of a Mordenite Zeolite by Low-Pressure SiCl4 Treatment to Catalyze Dimethyl Ether Carbonylation.

Controlling the location of aluminum atoms in a zeolite framework is critical for understanding structure-performance relationships of catalytic reaction systems and tailoring catalyst design. Herein, we report a strategy to preferentially relocate mordenite (MOR) framework Al atoms into the desired T3 sites by low-pressure SiCl4 treatment (LPST). High-field 27 Al NMR was used to identify the exact location of framework Al for the MOR samples. The results indicate that 73 % of the framework Al atoms were at the T3 sites after LPST under optimal conditions, which leads to controllably generating and intensifying active sites in MOR zeolite for the dimethyl ether (DME) carbonylation reaction with higher methyl acetate (MA) selectivity and much longer lifetime (25 times). Further research reveals that the Al relocation mechanism involves simultaneous extraction, migration, and reinsertion of Al atoms from and into the parent MOR framework. This unique method is potentially applicable to other zeolites to control Al location.

Accurate placement of cervical pedicle screws using 3D-printed navigational templates : An improved technique with continuous image registration.

OBJECTIVE: Accurate placement of cervical pedicle screws remains a surgical challenge. This study aimed to test the feasibility of using a novel three-dimensional (3D-)printed navigational template to overcome this challenge. METHODS: Cervical spines were scanned using computed tomography (CT). A 3D model of the cervical spines was created. The screw trajectory was designed to pass through the central axis of the pedicle. Thereafter, a navigational template was designed by removing the soft tissue from the bony surface in the 3D model. A 3D printer was used to print the navigational template. The screws were then placed in the cadavers following CT scanning. The 3D model of the designed trajectory and the placed screws were registered. The coordinates of the entry and exit points of the designed trajectory and the actual trajectory were recorded. The numbers of qualified points that met the different degrees of accuracy were compared using a χ2 test. RESULTS: A total of 158 screws were placed. Five screws breached the pedicle cortex with a distance <2 mm. There was no significant difference between the pre- and postoperative entry points with a degree of accuracy ≥1.7 mm (P = 0.131). Meanwhile, there was no significant difference between the pre- and postoperative exit points with degrees of accuracy ≥6.4 mm (P = 0.071). CONCLUSION: A navigational template can be designed by removing the soft tissue from the bony surface in a CT-generated 3D model. This guiding tool may effectively prevent intraoperative drifting and accurately places cervical pedicle screws.

Application of a novel 3D drill template for cervical pedicle screw tunnel design: a cadaveric study.

PURPOSE: To develop and validate the efficacy and accuracy of a three-dimensional (3D) computed tomography (CT) reconstructive rapid prototyping drill template for cervical pedicle screw placement. METHODS: CT thin-layer scans were obtained from 12 adult cadaveric cervical specimens and reconstructed. The ideal screw channels were chosen by analyzing the cross sections of the reconstructed 3D images. The navigation templates were designed and printed based on the optimal screw channels. The pedicle screws were placed on the cadaver specimens under template guidance, and the cadaver specimens were scanned and reconstructed. The pre- and post-operative models were compared. Entry point and exit point data of these two models were collected and compared using the Chi-square test. RESULTS: A total of 164 cervical pedicle screws were placed; among them, six punctured the cortical bone of the vertebral pedicle reaching an accuracy of 96.3%. Among the outside screws, all of the deviation distances were <2 mm. The Chi-square test results showed that when a deviation of 1.2 mm was used as a standard for the entry point, there was no difference between the two groups (χ 2 = 1.346, p = 0.248); when a deviation of 2.2 mm was used as a standard for the exit point, there was no difference between the two groups (χ 2 = 3.250, p = 0.061). CONCLUSION: The 3D CT reconstructive rapid prototyping drill template combined with the screw tunnel design based on 3D cutting technique can help facilitate accurate cervical pedicle screw insertion.

[Digital design of internal fixation for distal femoral fractures via 3D printing and standard parts database].

OBJECTIVE: To study the method of internal fixation by the navigation embedded plate from standard parts database for the distal femoral fractures based on digital design by Mimics software with 3D printing technology, and to explore its feasibility and accuracy. METHODS: A total of 21 cases with distal femoral fractures admitted into the Department of Orthopedics, Affiliated Hospital of Putian University were included in this study. Dicom format data of lamellar CT scanning was imported into Mimics software for 3D anatomical modeling and virtual fracture reduction. The steel plates was chose from standard parts database for virtual internal fixation, and to design the navigation module with screw. 3D printing skeleton, steel plates, navigation module, internal fixation implants were simulated based on the printed bones model. Locations of steel plates and screws were determined by the navigation module. Then the sticking effects of navigation module, screws position and postoperative appearance were observed. After second CT scan and 3D reconstruction, 3D registration was performed to obtain the data of the three-dimensional coordinate values of screws entrance points and piercing points to analyze the results. RESULTS: A total of 21 plates and 180 screws were placed with the assistance of navigation module. CT scanning and 3D reconstruction was performed in twenty-one cases of postoperative bone model. The position of plates was in high accordance with the digital design by Mimics software. There were no significant differences between spatial location of screw entrance points and piercing points. The real operation was quite consistent with preoperative design. Navigation module and the corresponding distal femur bony structure jointed closely. The sticking effects and stability of navigation module were good, which was able to guide placement of steel plates and screws. CONCLUSION: These methods can enhance the accuracy of internal fixation of the standard parts database steel plate in distal femur fractures, with the assistance of navigation module.

The impact of time from injury to surgery on the risk of neuropathic pain after traumatic spinal cord injury.

Traumatic spinal cord injury (SCI) is a devastating neurological disorder often accompanied by neuropathic pain (NeP), significantly affecting patients' quality of life. This retrospective study aimed to investigate the impact of the time from injury to surgery on the development of NeP following traumatic SCI. Medical records of patients with traumatic SCI who underwent surgical intervention between January 2017 and January 2021 at two specialized centers were reviewed. Variables associated with NeP including demographics, injury profiles, medical history, surgical details, and pain assessments were investigated. Independent risk factors related to NeP were identified using multivariate logistic regression analysis. A total of 320 patients met the inclusion criteria, with 245 (76.6%) being male and a mean age of 56.5 ± 13.2 years. NeP was identified in 48.4% of patients (155 of 320). The multivariate analysis identifies age at injury, Injury Severity Score, and the neurological level of injury as independent risk factors for the development of NeP in both AIS A and AIS B, C, and D subgroups. Additionally, a significant association between the time from injury to surgery and NeP was observed in AIS B, C, and D patients, while no such association was found in AIS A patients. This study highlights the benefits of early and ultra-early surgical intervention in preventing NeP in patients with incomplete traumatic SCI (AIS B, C, and D), underscoring the importance of optimizing surgical timing to improve patient outcomes. Prospective studies are warranted to establish evidence-based surgical guidelines for managing traumatic SCI and preventing NeP effectively.

Morphometric measurement of lower lumbar intervertebral foramina based on digital three-dimensional simulation.

AIM: This study aimed to investigate the morphology of the lower lumbar intervertebral foramina through use of a digital three-dimensional (3D) simulation model to guide the endoscope through the intervertebral foramina. MATERIAL AND METHODS: Individuals without disease affecting the lumbar vertebrae underwent computed tomography (CT) scanning in the supine position. The CT images obtained were imported to medical software to reconstruct a 3D model of the lumbar vertebrae. The stereoscopic longitudinal and transverse diameters of the lumbar intervertebral foramina were measured directly on the established simulation model. Comparisons in terms of sex and age were performed using t-test or analysis of variance. RESULTS: In total, 100 individuals were included in the study. Average longitudinal and transverse diameters of the lower lumbar intervertebral foramen decreased moving inferiorly. The longitudinal and transverse diameters of the lower lumbar intervertebral foramina were similar between sexes and between age groups. However, longitudinal diameter decreased with age (P 0.05). CONCLUSION: The reconstructed lumbar vertebrae simulation model presented in this study has high fidelity to the structure of the human lumbar spine. This approach provides individualized, accurate, standardized, and detailed guidance for endoscopic surgery through the lumbar intervertebral foramen.

A new route for the synthesis of propylene oxide from bio-glycerol derivated propylene glycol.

The synthesis of propylene oxide from propylene glycol, a derivative of bio-glycerol, was firstly realized in the presence of alkali-loaded silica catalysts to achieve 44% conversion and 70% selectivity.

Proximal humeral internal locking plate combined with a custom neutral-position shoulder and elbow sling for proximal humerus fractures: A randomized study.

OBJECTIVES: The aim of this study was to investigate the effectiveness of the proximal humeral internal locking system (PHILOS) plate combined with a custom neutral-position shoulder and elbow sling for proximal humerus fractures. METHODS: A total of 112 patients with proximal humerus fractures were assigned randomly into 2 groups. Group A (n = 56) was treated by open reduction and internal fixation (ORIF) with a PHILOS plate; group B (n = 56) was treated by ORIF with a PHILOS plate in combination with the use of a custom neutral-position shoulder and elbow sling for 30 days after surgery. The incidence of internal fixation failure, the Constant-Murley shoulder assessment, and Visual Analogue Scale (VAS) score were recorded and analyzed. RESULTS: Patients included were followed up for an average of 15 months (range, 6-24 months). No significant differences were observed in mean VAS scores and mean Constant-Murley shoulder assessment scores at 1-day preoperative and postoperative day 3 between groups A and B. However, mean VAS scores and mean Constant-Murley shoulder assessment in group B were significantly improved when compared with group A at postoperative day 30 and the final follow-up. No cases of postoperative infection, loss of reduction, PHILOS break, or vascular nerve injury occurred in either group. CONCLUSIONS: Proximal humerus fractures treated with the combination of the PHILOS and custom neutral-position shoulder and elbow sling for 30 days after operation was associated with a lower incidence of internal fixation failure. There was no increase in adverse events compared with open reduction and internal fixation with a PHILOS plate alone.

Accurate fixation of plates and screws for the treatment of acetabular fractures using 3D-printed guiding templates: An experimental study.

OBJECTIVE: To investigate the feasibility of the use of 3D-printed guiding templates for accurate placement of plates and screws for internal fixation of acetabular fractures. METHODS: 3D models of the pelvises of 14 adult cadavers were reconstructed using computed tomography (CT). Twenty-eight acetabular fractures were simulated and placement positions for plates and screw trajectories were designed. Bending module was obtained by 3D cutting; guiding template was manufactured using 3D printing, and the plate was pre-bent according to the bending module. Plates and screws were placed in cadaveric pelvises using the guiding template, and 3D model was reconstructed using CT. The designed and real trajectories were matched using 3D registration including the coordinates (entry and exit points) of designed trajectory. The number of qualified points with different accuracy levels was compared using Chi-squared test. RESULTS: Sixty-four plates and 339 screws were placed with no cortical breach. The absolute difference of the X, Y, and Z coordinates between the designed and real entry points were 0.52±0.45, 0.43±0.36, and 0.53±0.44mm, respectively. The corresponding values for the exit points were 0.83±0.67, 1.22±0.87, and 1.26±0.83mm, respectively. With an accuracy degree ≥1.9mm for the entry points and ≥3.8mm for the exit points, there was no significant difference between the designed and the real trajectories. CONCLUSION: The 3D-printed guiding template helped achieve accurate placement of plates and screws in the pelvis of adult cadavers.

[Clinical application of accurate placement of lumbar pedicle screws using three-dimensional printing navigational templates under Quadrant system].

Objective: To explore the feasibility and the effectiveness of the accurate placement of lumbar pedicle screws using three-dimensional (3D) printing navigational templates in Quadrant minimally invasive system. Methods: The L 1-5 spines of 12 adult cadavers were scanned using CT. The 3D models of the lumbar spines were established. The screw trajectory was designed to pass through the central axis of the pedicle by using Mimics software. The navigational template was designed and 3D-printed according to the bony surface where the soft tissues could be removed. The placed screws were scanned using CT to create the 3D model again after operation. The 3D models of the designed trajectory and the placed screws were registered to evaluate the placed screws coincidence rate. Between November 2014 and November 2015, 31 patients with lumbar instability accepted surgery assisted with 3D-printing navigation module under Quadrant minimally invasive system. There were 14 males and 17 females, aged from 42 to 60 years, with an average of 45.2 years. The disease duration was 6-13 months (mean, 8.8 months). Single segment was involved in 15 cases, two segments in 13 cases, and three segments in 3 cases. Preoperative visual analogue scale (VAS) was 7.59±1.04; Oswestry disability index (ODI) was 76.21±5.82; and the Japanese Orthopaedic Association (JOA) score was 9.21±1.64. Results: A total of 120 screws were placed in 12 cadavers specimens. The coincidence rate of placed screw was 100%. A total of 162 screws were implanted in 31 patients. The operation time was 65-147 minutes (mean, 102.23 minutes); the intraoperative blood loss was 50-116 mL (mean, 78.20 mL); and the intraoperative radiation exposure time was 8-54 seconds (mean, 42 seconds). At 3-7 days after operation, CT showed that the coincidence rate of the placed screws was 98.15% (159/162). At 4 weeks after operation, VAS, ODI, and JOA score were 2.24±0.80, 29.17±2.50, and 23.43±1.14 respectively, showing significant differences when compared with preoperative ones ( t=14.842, P=0.006; t=36.927, P=0.002; t=-36.031, P=0.001). Thirty-one patients were followed up 8-24 months (mean, 18.7 months). All incision healed by first intention, and no complication occurred. During the follow-up, X-ray film and CT showed that pedicle screw was accurately placed without loosening or breakage, and with good fusion of intervertebral bone graft. Conclusion: 3D-printing navigational templates in Quadrant minimally invasive system can help lumbar surgery gain minimal invasion, less radiation, and accurate placement.

[Effectiveness of distal femoral osteotomy assisted by three-dimensional printing technology for correction of valgus knee with osteoarthritis].

Objective: To evaluate the effectiveness of distal femoral osteotomy aided by three-dimensional (3D) printing cutting block for correction of vaglus knee with osteoarthritis. Methods: Between January 2014 and January 2016, 12 patients (15 knees) with vaglus deformity and lateral osteoarhritis underwent medial closing wedge distal femoral osteotomy. There were 5 males and 7 females, aged 30-60 years (mean, 43.8 years). The mean disease duration was 6.6 years (range, 1-12 years). The unilateral knee was involved in 9 cases and bilateral knees in 3 cases. According to Koshino's staging system, 1 knee was classified as stage I, 9 knees as stage II, and 5 knees as stage III. The X-ray films of bilateral lower extremities showed that the femorotibial angle (FTA) and anatomical lateral distal femoral angle (aLDFA) were (160.40±2.69)° and (64.20±2.11)° respectively. Mimics software was used to design and print the cutting block by 3D printing technique. During operation, the best location of distal femoral osteotomy was determined according to the cutting block. After osteotomy, internal fixation was performed using a steel plate and screws. Results: All incisions healed primarily; no complication of infection or deep vein thrombosis was observed. All patients were followed up 6-18 month (mean, 12.2 months). At 6 months after operation, the hospital for special surgery (HSS) score for knee was significantly improved to 89.07±2.49 when compared with preoperative score (65.27±1.49, t=-28.31, P=0.00); the results were excellent in 10 knees, good in 4 knees, and fair in 1 knee with an excellent and good rate of 93.3%. The bony union time was 2.9-4.8 months (mean, 3.3 months). Bone delayed union occurred in 1 case (1 knee). The postoperative FTA and aLDFA were (174.00±1.41)° and (81.87±1.06)° respectively, showing significant differences when compared with preoperative ones ( t=-18.26， P=0.00; t=-25.19, P=0.00). The percentage of medial tibial plateau in whole tibial plateau was 49.78%±0.59%, showing no significant difference when compared with intraoperative measurement (49.82%±0.77%, t=0.14, P=0.89). Conclusion: 3D printing cutting block can greatly improve the accuracy of distal femoral osteotomy, and ensure better effectiveness for correction of vaglus knee with osteoarthritis.

[EFFECTIVENESS OF HIGH TIBIAL OSTEOTOMY ASSISTED BY THREE- DIMENSIONAL PRINTING TECHNOLOGY FOR CORRECTION OF VARUS KNEE WITH OSTEOARTHRITIS].

OBJECTIVE: To evaluate the effectiveness of high tibial osteotomy (HTO) assisted by three-dimensional (3-D) printing technology for correction of varus knee with osteoarthritis. METHODS: Between January 2014 and June 2015, 16 patients (20 knees) with varus knee and osteoarthritis underwent HTO assisted by 3-D printing technology; a locking compression plate was used for internal fixation after HTO. There were 6 males and 10 females, aged 30-60 years (mean, 45.5 years). The disease duration was 1-10 years (mean, 6.2 years). The unilateral knee was involved in 12 cases and bilateral knees in 4 cases. According to Koshino's staging system, 3 knees were classified as stage I, 7 knees as stage II, 8 knees as stage III, and 2 knees as stage IV. Preoperative Hospital for Special Surgery (HSS) knee score was 63.8 ± 2.2; the femorotibial angle was (184.8 ± 2.9)°; and Insall-Salvati index was 1.03 ± 0.13. RESULTS: All the wounds healed primarily, and no complication of infection, osteofacial compartment syndrom, or deep vein thrombosis was observed. All patients were followed up 6-18 months (mean, 12.6 months). Personal paralysis was observed in 1 case (1 knee), and was cured after expectant treatment. Bone union time was 2.7-3.4 months (mean, 2.9 months). At 6 months after operation, the femorotibial angle was (173.8 ± 2.0)°, showing significant difference when compared with preoperative one (t = 11.70, P = 0.00); Insall-Salvati index was 1.04 ± 0.12, showing no significant difference when compared with preoperative one (t = -0.20, P = 0.85); and HSS knee score was significantly increased to 88.9 ± 3.1 (t = -25.44, P = 0.00). At last follow-up, the results were excellent in 13 knees, good in 6 knees, fair in 1 knee, and the excellent and good rate was 95%. CONCLUSION: 3-D printing cutting block can greatly improve the accuracy of HTO, avoid repeated X-ray and multiple osteotomy, shorten the operation time, and ensure better effectiveness for correction of varus knee with osteoarthritis.

[DIGITAL DESIGN OF STANDARD PARTS DATABASE FOR PROXIMAL TIBIA FRACTURES TREATED WITH PLATING VIA THREE-DIMENSIONAL PRINTING].

OBJECTIVE: To explore the method and feasibility of digital internal fixation for proximal tibia fractures using standard parts database and three-dimensional (3D) printing technology. METHODS: Ten adult lower extremity specimens were selected to take continuously thin-layer scanning. After Dicom image was imported into the Mimics software, the model of Schatzker II-VI types proximal tibia fracture was established, 2 cases each type. The virtual internal fixation was performed with plate and screw from standard parts database. The pilot hole of the navigation module design was printed by 3D printing technique. The plate and screw were inserted by the navigation module. X-ray film and CT were taken postoperatively to observe the position. Thirty patients with proximal tibia fracture underwent digital internal fixation using standard parts database and 3D printing technology (study group), and another 30 patients underwent traditional open reduction and internal fixation (control group). There was no significant difference in sex, age, side, causes, fracture classification, associated injury, and course of disease between 2 groups (P > 0.05). The preparative time, incision length, fracture healing time, operation time, and intraoperative blood loss were recorded. Follow up of imaging evaluation, clinical efficacy was evaluated by MacNab criteria. RESULTS: The navigation models were designed to fit the bony structure of proximal tibia and to guide implant insertion. The parameters of orientation, length, diameter, and angle were consistent with the preoperative plan. No statistically significant difference was found in the preparative times of pre-operation between 2 groups (t = 1.393, P = 0.169). The incision length, wound healing time, blood loss, operation time, and the cost of treatment in study group were significantly less than those in control group (P < 0.05). All patients were followed up 12-16 months (mean, 13.5 months). The fracture healing time of study group was significantly shorter than that of control group (t = 4.070, P = 0.000). At 12 months postoperatively, there was no significant difference in the efficacy based on MacNab criteria between 2 groups (U = 377.000, P = 0.238). CONCLUSION: Digital internal fixation for proximal tibia fractures using standard parts database and 3D printing technology has the advantages of short process, less blood loss, high safety and rapid fracture healing.