Losses of low-germinating, slow-growing species prevent grassland composition recovery from nutrient amendment.

Nutrient enrichment often alters the biomass and species composition of plant communities, but the extent to which these changes are reversible after the cessation of nutrient addition is not well-understood. Our 22-year experiment (15 years for nutrient addition and 7 years for recovery), conducted in an alpine meadow, showed that soil nitrogen concentration and pH recovered rapidly after cessation of nutrient addition. However, this was not accompanied by a full recovery of plant community composition. An incomplete recovery in plant diversity and a directional shift in species composition from grass dominance to forb dominance were observed 7 years after the nutrient addition ended. Strikingy, the historically dominant sedges with low germination rate and slow growth rate and nitrogen-fixing legumes with low germination rate were unable to re-establish after nutrient addition ceased. By contrast, rapid recovery of aboveground biomass was observed after nutrient cessation as the increase in forb biomass only partially compensated for the decline in grass biomass. These results indicate that anthropogenic nutrient input can have long-lasting effects on the structure, but not the soil chemistry and plant biomass, of grassland communities, and that the recovery of soil chemical properties and plant biomass does not necessarily guarantee the restoration of plant community structure. These findings have important implications for the management and recovery of grassland communities, many of which are experiencing alterations in resource input.

The Hoffa-like fracture of the tibial plateau: a clinical study.

BACKGROUND: Given the contrapositive link between the posterior tibial plateau and the femoral condyle and the similar injury cause, the fracture type should be the same as the well-known Hoffa fracture of the femoral condyle. This study aims to report a case series with Hoffa-like tibial plateau fractures to improve understanding. METHODS: We analysed six consecutive patients presented with Hoffa-like tibial plateau fractures in our hospital between October 2014 and December 2020, a period in which 1924 tibial plateau fractures were treated. Patients' data on demographics, radiographs, surgical therapy, and assessment at a 12-month follow-up were retrieved. RESULTS: The incidence of Hoffa-like tibial plateau fractures was 0.31% (6/1924). This study included three men and three women, with a mean age of 45.8 years. The injury mechanism was either a fall from a great height or a vehicle accident. On average, 7.5 days after the injury, patients were surgically treated with open reduction and internal fixation (ORIF) with place/screws via a lateral or posteromedial approach. At 10 to 15 weeks, all instances had osseous union on radiography. At 12-month follow-up, the HSS score of the operated knee ranged from 93 to 98 points (mean: 94.8), and Rasmussen radiograph score was from 15 to 18 (mean: 15.8). There were no intra-operative or post-operative problems. CONCLUSION: This Hoffa-like fracture of the tibial plateau is a rare condition; however, it can occur. Orthopaedic surgeons should pay attention to this neglected but actually familiar fracture type.

Surgeon volume and the risk of deep surgical site infection following open reduction and internal fixation of closed tibial plateau fracture.

BACKGROUND: Emerging evidences supported that the surgeon case volume significantly affected post-operative complications or outcomes following a range of elective or non-elective orthopaedic surgery; no data has been available for surgically treated tibial plateau fractures. We aimed to investigate the relationship between surgeon volume and the risk of deep surgical site infection (DSSI) following open reduction and internal fixation (ORIF) of closed tibial plateau fracture. METHODS: This was a further analysis of the prospectively collected data. Adult patients undergoing ORIF procedure for closed tibial plateau fracture between January 2016 and December 2019 were included. Surgeon volume was defined as the number of surgically treated tibial fractures in the preceding 12 months and dichotomized on the basis of the optimal cut-off value determined by the receiver operating characteristic (ROC) curve. The outcome was DSSI within one year post-operatively. Multiple multivariate logistic models were constructed for "drilling down" adjustment of confounders. Sensitivity and subgroup analyses were performed to assess the robustness of outcome and identify the "optimal" subgroups. RESULTS: Among 742 patients, 20 (2.7%) had a DSSI and 17 experienced re-operations. The optimal cut-off value for case volume was nine, and the low-volume surgeon was independently associated with 2.9-fold (OR, 2.9; 95%CI, 1.1 to 7.5) increased risk of DSSI in the totally adjusted multivariate model. The sensitivity analyses restricted to patients with original BMI data or those operated within 14 days after injury did not alter the outcomes (OR, 2.937, and 95%CI, 1.133 to 7.615; OR, 2.658, and 95%CI, 1.018 to 7.959, respectively). The subgroup analyses showed a trend to higher risk of DSSI for type I-IV fractures (OR, 4.6; 95%CI, 0.9 to 27.8) classified as Schatzker classification and substantially higher risk in patients with concurrent fractures (OR, 6.1; 95%CI, 1.0 to 36.5). CONCLUSION: The surgeon volume is independently associated with the rate of DSSI, and a number of ≥ nine cases/year are necessarily kept for reducing DSSIs; patients with concurrent fractures should be preferentially operated on by high-volume surgeons.

Multiplanar fracture reducer versus manual traction in the treatment of tibial shaft fractures with intramedullary nails.

OBJECT: The purpose of this study was to propose a new traction device, a multiplanar fracture reducer (MFR), for the treatment of tibial shaft fractures with intramedullary nails (IMN). The efficiencies of the multiplanar fracture reducer and manual traction (MT) in the treatment of tibial shaft fractures with IMN were compared. METHODS: From January 2019 to January 2020, a total of 79 patients were enrolled in this study, among whom 38 were treated with MFR while 41 were treated with MT. Their demographics and fracture characteristics, surgical data, and prognostic data between the two groups were compared. RESULTS: The mean number of intra-operative fluoroscopies in the MFR group was less than that in the MT group (19.4 vs 21.2, p < 0.001); surgical procedures involving open reduction were more in the MT group than in MFR group (0 vs 5, p = 0.026); there were less assistants in the MFR group than in the MT group (1 vs 1.9, p < 0.001), while the average Lysholm Knee Function Score and knee flexion were 92.7 ± 2.0 and 128.8 ± 1.4 in the MFR group, and 91.9 ± 2.1 and 127.5 ± 1.8 in the MT group, respectively. Both LKFS and knee flexion in the MFR group were significantly better than those in the MT group (p = 0.032 and p < 0.001). The remaining data between the two groups were comparable. CONCLUSION: MFR is a safe and effective device for the minimal invasive treatment of tibial shaft fractures fixed with IMN.

Relationship between surgeon volume and the risk of deep surgical site infection (DSSI) following open reduction and internal fixation of displaced intra-articular calcaneal fracture.

It is well established that the postoperative results were affected by the surgeon volume in a variety of elective and emergent orthopaedic surgeries; however, by far, no evidences have been available as for surgically treated displaced intra-articular calcaneal fractures (DIACFs). We aimed at investigating the relationship between surgeon volume and deep surgical site infection (DSSI) following open reduction and internal fixation (ORIF) of DIACFs. This was a further analysis of prospectively collected data from a validated database. Patients with DIACFs stabilised by ORIF between 2016 and 2019 were identified. Surgeon volume was defined as the number of surgically treated calcaneal fractures within one calendar year and was dichotomised based on the optimal cut-off value. The outcome measure was DSSI within 1 year postoperatively. Multivariate logistics regression analyses were performed to examine the relationship, adjusting for confounders. Among 883 patients, 19 (2.2%) were found to have a DSSI. The DSSI incidence was 6.5% in surgeons with a low volume (<6/year), 5.5 times as that in those with a high volume (≥6/year) (incidence rate, 1.2%; P < 0.001). The multivariate analyses showed a low volume <6/year was associated with a 5.8-fold increased risk of DSSI (95% confidence interval, 2.2-16.5, P < 0.001). This value slightly increased after multiple sensitivity analyses, with statistical significances still unchanged (OR range, 6.6-6.9; P ≤ 0.001). The inverse relationship indicates a need for at least six cases/year for a surgeon to substantially reduce the DSSIs following the ORIF of DIACFs.

Incidence and predictors of surgical site infection after distal femur fractures treated by open reduction and internal fixation: a prospective single-center study.

BACKGROUND: There remain limited data on the epidemiological characteristics and related predictors of surgical site infection (SSI) after open reduction and internal fixation (ORIF) for distal femur fractures (DFFs). We designed this single-centre prospective study to explore and forecast these clinical problems. METHODS: From October 2014 to December 2018, 364 patients with DFFs were treated with ORIF and followed for complete data within one year. Receiver operating characteristic (ROC) analyses, univariate Chi-square analyses, and multiple logistic regression analyses were used to screen the adjusted predictors of SSI. RESULTS: The incidence of SSI was 6.0 % (22/364): 2.4 % (9/364) for superficial SSIs and 3.6 % (13/364) for deep SSIs. Staphylococcus aureus (methicillin-resistant S. aureus in 2 cases) was the most common pathogenic bacteria (36.8 %,7/19). In multivariate analysis, parameters independently associated with SSI were: Open fracture (OR: 7.3, p = 0.003), drain use (OR: 4.1, p = 0.037), and incision cleanliness (OR: 3.5, p = 0.002). An albumin/globulin (A/G) level ≥ 1.35 (OR: 0.2, p = 0.042) was an adjusted protective factor for SSI. CONCLUSIONS: The SSI after ORIF affected approximately one in 15 patients with DFFs. The open fracture, drain use, high grade of intraoperative incision cleanliness, and preoperative A/G levels lower than 1.35 were significantly related to increasing the risk of post-operative SSI after DFFs. We recommended that more attentions should be paid to these risk factors during hospitalization. TRIAL REGISTRATION: NO 2014-015-1, October /15/2014, prospectively registered. We registered our trial prospectively in October 15, 2014 before the first participant was enrolled. This study protocol was conducted according to the Declaration of Helsinki and approved by the Institutional Review Board. The ethics committee approved the Surgical Site Infection in Orthopaedic Surgery (NO 2014-015-1). Data used in this study were obtained from the patients who underwent orthopaedic surgeries between October 2014 to December 2018.

Post-operative deep vein thrombosis in patients over sixty years of age diagnosed with closed distal femur fractures undergoing open reduction internal fixation.

BACKGROUND AND PURPOSE: New-onset deep vein thrombosis (DVT) reportedly affects prognosis and surgical outcomes of elderly patients. However, its effect on distal femur fractures (DFFs) remains unclear. We aimed to address the epidemiological characteristics and the associated predictors for post-operative DVT in patients with closed DFFs over age 60 years old. PATIENTS AND METHODS: We designed a prospective cohort trial at our hospital between October 2018 and June 2020 and recruited consecutive 140 patients over age 60 years diagnosed with closed DFFs. We examined location and prognosis of postoperative DVT and then conducted a three month follow-up. We used Duplex ultrasonography (DUS) to diagnose DVT in all patients and then classified the subjects into DVT and non-DVT groups. We further classified DVTs into proximal, distal, and mixed thromboses and then performed Whitney U test or t test, receiver operating characteristic (ROC) curve analysis, Chi-square test, and multiple logistic regression analysis to confirm the adjusted factors of post-operative DVT. RESULTS: We found a 35% (n = 49) overall incidence of post-operative DVTs, which occurred 5.7 days following open reduction internal fixation (ORIF). Among patients with post-operative DVTs, 53.1% (n = 26) and 10.2% (n = 5) were distal and proximal thromboses, respectively. Additionally, peroneal veins were the most common DVT sites (71.4%, n = 35). Multivariate analysis revealed that venous thrombosis at admission (odds ratio [OR], 4.619; 95% confidence interval [CI]: 2.072-10.299; P = 0.000), operation duration over 195 minutes (OR, 3.289; 95% CI, 1.155-9.370; P = 0.026), intra-operative blood loss over 325 mL (OR, 2.538; 95% CI, 1.047-6.155; P = 0.039) were the three independent risk factors of post-operative DVT. Unified antithrombotic agents after diagnosis showed that 16.3% (n = 8) of DVTs were completely recanalized, 12.6 days after first diagnosis. CONCLUSION: Our findings indicate a strong association between venous thrombosis at admission, the longer operation duration, and considerable intra-operative blood loss with high risk of post-operative DVTs in patients over age 60 years with closed DFFs. Preventive approaches for postoperative DVTs should seek to shorten operation duration and reduce intra-operative blood loss.

Traction methods in the retrograde intramedullary nailing of femur shaft fractures: the double reverse traction repositor or manual traction.

OBJECTIVE: The purpose of this prospective study was to compare the double reverse traction repositor (DRTR) and manual traction in retrograde intramedullary nailing (RE-IMN) for femoral shaft fractures. PATIENTS AND METHODS: Seventy-seven patients with femur shaft fractures were randomized to undergo surgery with either DRTR or manual traction (MT) to facilitate RE-IMN between January 2018 and January 2019. Demographics, fracture characteristics, surgical data, post-operative complications, and functional outcomes were assessed. Data from 72 patients completing the final follow-up (12 months) were analysed in this study. RESULTS: The average number of intra-operative perspectives in the DRTR group was 27.7, which was significantly reduced compared with that in the MT group (31.3, p < 0.001). Fewer assistants were required in the DRTR group compared with the MT group (1.1 vs 1.9, p < 0.001). Fewer patients with open reduction were discovered in the DRTR group compared with the MT group (2.8 vs 19.4, p=0.024). Demographics, fracture characteristics, other surgical data, and prognostic parameters were comparative between the two groups. CONCLUSIONS: The DRTR can be effectively and safely used to treat femur shaft fractures with RE-IMN. The DRTR achieves similar results as MT and is also superior to MT in terms of intra-operative perspectives, the number of assistants, and the open reduction rate.

Prevalence of Preoperative Lower Extremity Deep Vein Thrombosis in Bilateral Calcaneal Fractures.

There are no studies on epidemiologic characteristics of deep vein thrombosis (DVT), when specified at in patients with bilateral calcaneal fractures. This study aimed to address the preoperative DVT in bilateral calcaneal fractures. Between October 2014 and December 2018, adult patients presenting with bilateral calcaneal fractures and having preoperative Duplex ultrasound (DUS) of bilateral lower extremities for detection of DVT were included. Their medical data were collected, with regards to demographics, comorbidities, injury-related data and biomarkers. Baseline characteristics between patients with and without DVT were compared using bivariate tests. The further multivariate logistics regression analysis was conducted to identify independent factors associated with DVT. In total, 258 patients with bilateral calcaneal fractures were included, with 21 (8.1%) having preoperative DVT, diagnosed at 7.7 ± 4.2 days after injury. The prevalence rate of proximal DVT was 1.9% and of distal DVT was 6.2%. Thirty five thrombi were found, with 6 (17.1%) in proximal veins and 29 (82.9%) in distal veins. Nine patients had DVTs in multiple veins, and 2 patients had bilateral DVTs. The multivariate analyses showed history of allergy (odds ratio [OR] = 2.17), concurrent other fractures (OR = 4.53), prolonged time since injury (for each day, OR = 1.16), elevated plasma D-dimer level (≥1.73 vs <1.73 mg/L, OR = 3.74) and reduced albumin level (<34.2 g/L vs ≥34.2 g/L, OR = 2.92) were independent factors associated with DVT. Multiple factors were identified to be associated with DVT and greater consideration should be given to the use of pharmacologic prophylaxis in patients involving these factors, to reduce DVT occurrence.

Incidence and risk factor for preoperative deep vein thrombosis (DVT) in isolated calcaneal fracture, a prospective cohort study.

BACKGROUNDS: Deep vein thrombosis (DVT) occurring during the preoperative waiting period may affect the prognosis of traumatic patients, but there still lack of relevant data. This study aimed to address the preoperative DVT in isolated calcaneal fractures. METHODS: Patients who presented with isolated calcaneal fracture and received preoperative Duplex ultrasound scanning of bilateral lower extremities for detection of DVT between October and December 2018 were eligible for inclusion. Relevant data were prospectively collected, including demographics, comorbidities, lifestyles, injury, and laboratory biomarkers at admission. Univariate analyses were used to compare the difference of each variable between patients with and without DVT. Multivariate logistics regression analysis was used to identify the independent risk factors for DVT. RESULTS: Totally, 770 patients met the criteria and were included, and 24 (3.1%) had preoperative DVT diagnosed at mean of 5.3 days after injury, all of which were asymptomatic. Among patients with DVTs, 36 thrombi were found and 29 (80.6%) were in distal veins. Eight patients had DVTs in multiple veins, but no patients had bilateral DVTs. The multivariate analyses showed older age (≥58 vs <58 years, OR = 3.84), delay from injury to DUS (in each day, OR = 1.23) and elevated plasma D-dimer level (≥1.79 vs <1.79 mg/L, OR = 2.53) were independent risk factors associated with DVT. CONCLUSIONS: Due to low prevalence of DVT in isolated fracture, routine throboprophylaxis is not recommended. However, emphasis should be given in older patients with delay to admission and elevated plasma D-dimer level for targeted detection of DVT and rapid therapeutic intervention.

Incidence and risk factors of surgical site infection after intertrochanteric fracture surgery: A prospective cohort study.

Surgical site infection (SSI) is a challenging complication after intertrochanteric fracture surgery but without a large-sample size study to investigate the incidence and risk factors of it. The present study was to investigate the incidence and risk factors of SSI after intertrochanteric fracture surgery. A total of 1941 patients underwent intertrochanteric fracture surgery between October 2014 and December 2018 were included. Demographic data, surgical variables, and preoperative laboratory indexes were obtained from a prospective database and reviewed by hospital records. The optimum cut-off value for quantitative data was detected by receiver operating characteristic analysis. The univariate analysis and multivariable analysis were conducted to analyse the risk factors. In total, 25 patients (1.3%) developed SSI, including 22(1.1%) superficial infection and 3(0.2%) deep infection. After adjustment of multiple variables, gender (odds ratio[OR] 2.64, P = .024), time to surgery>4 days (OR 2.41, P = .046), implant (intramedullary or extramedullary devices) (OR 2.96, P = .036), ALB<35 g/L (OR 2.88, P = .031) remained significant factors. In conclusion, the incidence of SSI after intertrochanteric fractures surgery was 1.3%, with 1.1% for superficial and 0.2% for deep infection. Gender, time to surgery>4 days, the implant (intramedullary or extramedullary devices), and ALB<35 g/L were independent risk factors for the rate of SSI.

Cis/trans Fluorescent Recognition by Naphthalimide Dyes ⊂ CB [7] Assembly.

A novel method to recognize cis/trans isomers was studied here. The naphthalimide dye as guest could bind with host cucurbit [7]uril (CB [7]) and 1:1 naphthalimide dye âŠ‚ CB [7] assembly was formed. Moreover, this assembly was used as a fluorescent probe to recognized Fumaric acid (FA) and maleic acid (MA) via fluorescence titration. Two carboxyls in MA are in the same side, they could form stable interaction with the assembly and the fluorescence intensity decreased obviously when naphthalimide dye âŠ‚ CB [7] was titrated by MA (nearly quenched in 1.5 equiv). But two carboxyls in FA are in opposite sides, the interaction between FA and the assembly was weak and not stable, and the fluorescence intensity changed inconspicuously when the assembly was titrated by FA.

Amplification of oxidative stress with a hyperthermia-enhanced chemodynamic process and MTH1 inhibition for sequential tumor nanocatalytic therapy.

During chemodynamic therapy (CDT), tumor cells can adapt to hydroxyl radical (˙OH) invasion by activating DNA damage repairing mechanisms such as initiating mutt homologue 1 (MTH1) to mitigate oxidation-induced DNA lesions. Therefore, a novel sequential nano-catalytic platform MCTP-FA was developed in which ultrasmall cerium oxide nanoparticle (CeO2 NP) decorated dendritic mesoporous silica NPs (DMSN NPs) were used as the core, and after encapsulation of MTH1 inhibitor TH588, folic acid-functionalized polydopamine (PDA) was coated on the periphery. Once endocytosed into the tumor, CeO2 with multivalent elements (Ce3+/4+) could transform H2O2 into highly toxic ˙OH through a Fenton-like reaction to attack DNA as well as eliminating GSH through a redox reaction to amplify oxidative damage. Meanwhile, controllable release of TH588 hindered the MTH1-mediated damage repair process, further aggravating the oxidative damage of DNA. Thanks to the excellent photothermal performance of the PDA shell in the near-infrared (NIR) region, photothermal therapy (PTT) further improved the catalytic activity of Ce3+/4+. The therapeutic strategy of combining PTT, CDT, GSH-consumption and TH588-mediated amplification of DNA damage endows MCTP-FA with powerful tumor inhibition efficacy both in vitro and in vivo.

Effect of Alteration in Precipitation Amount on Soil Microbial Community in a Semi-Arid Grassland.

Climate models predict significant changes in precipitation magnitude in semi-arid grasslands, so it is vital to improve our understanding of how changing precipitation affects microbial communities in grassland ecosystems. Using a long-term field manipulation experiment, we evaluated the responses of microbial communities to a decrease (DP) and an increase (IP) in precipitation on a semi-arid grassland in northern China. The results showed that bacterial species richness decreased significantly with DP but remained stable under IP. Relative abundance of oligotrophic, slow-growing bacterial phyla (e.g., Chloroflexi and Acidobacteria) increased with DP but decreased with IP, whereas the relative abundance of copiotrophic, fast-growing bacterial phyla (e.g., Proteobacteria and Bacteroidetes) decreased with DP but increased with IP. In contrast, diversity, species composition, and relative abundance of different fungal phyla change little with DP or IP. These results indicate a greater sensitivity of bacteria to precipitation changes than fungi, and the sensitivity of bacteria to DP was higher than IP. Our findings are important for understanding soil microbial dynamics under future climate change scenarios.

Differential Mechanisms Drive Species Loss Under Artificial Shade and Fertilization in the Alpine Meadow of the Tibetan Plateau.

Fertilization is an effective management strategy to promote community biomass but can simultaneously reduce species diversity in many grassland systems. Shifts in competition for resources have been proposed to explain the decline in plant species diversity due to fertilization, yet the underlying mechanism driving species loss remains controversial. This uncertainty may be driven by variation in aboveground and belowground resource availability. However, experiments simultaneously manipulating both light availability and soil nutrients are rare. Using a 6-year field experiment to manipulate light availability (via shade cloth) and soil nutrients (via fertilizer addition), we tested this resource competition hypothesis in a species-rich alpine meadow by examining the variation of species traits associated with the capacity of light acquisition within these treatments. Our results showed that artificial shade decreased community biomass accumulation whereas fertilization increased it. In contrast, both shade and fertilization reduced species diversity. Extinction of non-Gramineae species (e.g., Fabaceae and Cyperaceae) was the main reason for species diversity decline. Species loss can be explained by the limitation of light availability and predicted by species traits associated with light acquisition capability under fertilization and low light tolerance under artificial shade. Specifically, fertilization eliminated species with lower stature and artificial shade exterminated species with the higher light compensation point (LCP). The findings suggest that light availability is consistently important for plant growth and that low competitiveness for light under fertilization and intolerance of low light conditions under artificial shade trigger species loss process in the alpine meadow. Our experiment helps clarify the mechanisms of how artificial shade and fertilization decreased species diversity and highlight that LCP, which tends to be neglected by most of the studies, is one of the vital drivers in determining species coexistence.

Platinum-based nanocomposites loaded with MTH1 inhibitor amplify oxidative damage for cancer therapy.

Photodynamic therapy (PDT) is a promising therapeutic strategy for tumor ablation by generating highly toxic reactive oxygen species (ROS) to damage DNA and other biomacromolecules. However, the local hypoxic microenvironment of the tumor and the presence of ROS-defensing system, such as the mobilization of mutt homolog 1 (MTH1) to sanitize ROS-oxidized nucleotide pool, severely limit the efficiency of PDT. Therefore, a novel tumor ablation strategy was developed that not only focused on the enhancement of ROS generation but also weakened the ROS-defensing system by inhibiting MTH1 enzyme activity. In our work, a simple one-step reduction approach was applied to enable platinum nanoparticles (Pt NPs) with catalase activity to grow in situ in the nanochannels of mesoporous silica nanoparticles (MSNs). After physical encapsulation of photosensitizer chlorin e6 (Ce6) and MTH1 inhibitor TH588, the drug loading nanoplatform was modified with an arginine-glycine-aspartic acid (RGD) functionalized liposome shell, resulting in the fabrication of amplified oxidative damage nanoplatform MSN-Pt@Ce6/TH588 @Liposome-RGD (MPCT@Li-R). The prepared MPCT@Li-R NPs could continuously catalyze the decomposition of hydrogen peroxide (H2O2) into oxygen (O2) in tumor, thus promoting the generation of singlet oxygen during PDT process for improved oxidative damage of bases. Simultaneously, acid responsive released TH588 hindered MTH1-mediated scavenging of oxidative bases, further aggravating DNA oxidative damage. Consequently, this cascade therapy strategy exhibited excellent tumor suppression efficiency both in vitro and in vivo.

The onset of deep recycling of supracrustal materials at the Paleo-Mesoarchean boundary.

The recycling of supracrustal materials, and in particular hydrated rocks, has a profound impact on mantle composition and thus on the formation of continental crust, because water modifies the physical properties of lithological systems and the mechanisms of partial melting and fractional fractionation. On the modern Earth, plate tectonics offers an efficient mechanism for mass transport from the Earth's surface to its interior, but how far this mechanism dates back in the Earth's history is still uncertain. Here, we use zircon oxygen (O) isotopes to track recycling of supracrustal materials into the magma sources of early Archean igneous suites from the Kaapvaal Craton, southern Africa. The mean δ 18O values of zircon from TTG (tonalite-trondhjemite-granodiorite) rocks abruptly increase at the Paleo-Mesoarchean boundary (ca. 3230 million years ago; Ma), from mantle zircon values of 5‰-6‰ to approaching 7.1‰, and this increase occurs in ≤3230 Ma rocks with elevated Dy/Yb ratios. The 18O enrichment is a unique signature of low-temperature water-rock interaction on the Earth's surface. Because the later phase was emplaced into the same crustal level as the older one and TTG magmas would derive from melting processes in the garnet stability field (>40 km depth), we suggest that this evident shift in TTG zircon O isotopic compositions records the onset of recycling of the mafic oceanic crust that underwent seawater hydrothermal alteration at low temperature. The onset of the enhanced recycling of supracrustal materials may also have developed elsewhere in other Archean cratons and reflects a significant change in the tectonic realm during craton formation and stabilization, which may be important processes for the operation of plate tectonics on early Earth.

Incidence of and risk factors for new-onset deep venous thrombosis after intertrochanteric fracture surgery.

This study aimed to investigate the incidence of and risk factors for postoperative new-onset deep venous thrombosis (PNO-DVT) following intertrochanteric fracture surgery. Information on 1672 patients who underwent intertrochanteric fracture surgery at our hospital between January 2016 and December 2019 was extracted from a prospective hip fracture database. Demographic information, surgical data, and preoperative laboratory indices were analysed. Receiver operating characteristic curve analysis, univariate analyses and binary logistic regression analyses were performed. The incidences of postoperative deep venous thrombosis (DVT) and PNO-DVT in inpatients after intertrochanteric fracture surgery were 11.5% (202 of 1751 patients) and 7.4% (123 of 1672 patients), respectively. PNO-DVT accounted for 60.9% of postoperative DVT. Additionally, there were 20 cases of central thrombosis (16.3%), 82 cases of peripheral thrombosis (66.7%), and 21 cases of mixed thrombosis (17.1%). In addition, 82.1% of PNO-DVTs were diagnosed within 8 days after surgery. The multivariate analysis revealed that age > 70 years, duration of surgery (> 197 min), type of anaesthesia (general), and comorbidities (≥ 3) were independent risk factors for the development of PNO-DVT after intertrochanteric fracture surgery. This study demonstrated a high incidence of PNO-DVT in inpatients after intertrochanteric fracture surgery. Therefore, postoperative examination for DVT should be routinely conducted for patients.

Incidence and locations of preoperative deep venous thrombosis (DVT) of lower extremity following tibial plateau fractures: a prospective cohort study.

BACKGROUND: There is still lack of data on deep vein thrombosis (DVT) following bone trauma. This study aimed to determine the epidemiologic characteristics of deep venous thrombosis (DVT) of lower extremities following tibial plateau fractures. METHODS: Retrospective analysis of prospectively collected data on patients presenting with tibial plateau fractures between October 2014 and December 2018 was conducted. Duplex ultrasonography (DUS) was routinely used to screen for preoperative DVT of bilateral lower extremities. Data on demographics, comorbidities, injury-related data, and laboratory biomarkers at admission were collected. Univariate analyses and multivariate logistic regression analyses were used to identify the independent risk factors associated with DVT. RESULTS: A total of 1179 patients were included, among whom 192 (16.3%) had a preoperative DVT, with incidence rate of 1.0% for proximal and 15.3% for distal DVT. The average interval between fracture occurrence and diagnosis of DVT was 3.5 days (median, 2 days), ranging from 0 to 19 days. DVT involved the injured extremity in 166 (86.4%) patients, both the injured and uninjured extremities in 14 patients (7.3%) and only the uninjured extremity in 12 patients (6.3%). Six risk factors were identified to be associated with DVT, including gender (male vs female), hypertension, open fracture, alkaline phosphatase > 100 u/L, sodium concentration < 135 mmol/L, and D-dimer > 0.5 mg/L. CONCLUSION: These epidemiologic data are conducive to the individualized assessment, risk stratification, and development of targeted prevention programs.

Incidence and risk factors for decreased range of motion of the knee joint after surgery for closed tibial plateau fracture in adults.

PURPOSE: The aim of this study was to quantify the incidence of and identify independent risk factors for decreased range of motion (ROM) of the knee joint after surgery for closed tibial plateau fractures in adults. METHODS: This retrospective study was performed at the trauma centre in our hospital from January 2018 to December 2019. Data from adult patients with tibial plateau fractures treated by surgery were extracted from the electronic medical records. A total of 220 tibial plateau fracture patients were enrolled. We extracted the patients' demographic characteristics, fracture characteristics, and surgery-related variables. Univariate and multivariate logistic regression models were used to investigate the potential independent risk factors. RESULTS: Fifty-seven patients developed decreased ROM of the knee joint at the 1-year follow-up in this study. The overall incidence was 25.9%. The independent predictors of decreased ROM after surgery, as identified in the multivariate analysis, were orthopedic polytrauma (odds ratio = 3.23; 95% CI = 1.68-6.20; p = 0.000), fracture type (Schatzker V-VI) (odds ratio = 2.52; 95% CI = 1.16-5.47; p = 0.019), and an open reduction and internal fixation approach (odds ratio = 2.10; 95% CI = 1.07-4.12; p = 0.031). CONCLUSIONS: The study confirmed that patients with orthopaedic polytrauma, more complex fractures and those treated with open reduction and internal fixation (ORIF) surgery were more likely to suffer decreased ROM of the knee joint 1 year after surgery.