A new series of spiro‐bicyclic bisborane catalysts has been prepared by means of hydroboration reactions of C2‐symmetric spiro‐bicyclic dienes with HB(C6F5)2 and HB(p‐C6F4H)2. When used for ...hydrogenation of quinolines, these catalysts give excellent yields and enantiomeric excesses, and show turnover numbers of up to 460. The most attractive feature of these metal‐free hydrogenation reactions was the broad functional‐group tolerance, making this method complementary to existing methods for quinoline hydrogenation.
B,B bicycles: A series of C2‐symmetric spiro‐bicyclic bisboranes has been prepared. These bisboranes demonstrate highly effective and selective asymmetric hydrogenation of quinolines. The exceedingly broad functional‐group tolerance allows access to various enantioenriched and functionalized tetrahydroquinilines, which are inaccessible by previous methods using either borane or transition‐metal catalysts.
We prepared a new class of chiral C2‐symmetric bicyclic bisborane catalysts by addition reactions of internal dienes with the Piers borane, HB(C6F5)2, and an analogue, HB(p‐C6F4H)2. The dependence of ...the addition pattern on the reaction temperature allowed us to selectively prepare two diastereomeric catalysts from a single diene precursor. The bisboranes prepared in situ exhibited excellent activity (turnover numbers up to 200 at −40 °C) and enantioselectivity (up to 95 % ee) in imine hydrogenation reactions.
B,B bicycles: A new class of C2‐symmetric bicyclic bisborane catalysts was synthesized by treating bicyclic dienes with HB(C6F5)2 or HB(p‐C6F4H)2. Remarkably, two diastereomeric catalysts could be accessed selectively from a single diene precursor by simply varying the reaction temperature (see scheme). These catalysts exhibited excellent activity and selectivity in the hydrogenation of imines.
Catalytic amounts of B(C6F5)3 have been found to be able to promote the intramolecular cyclization of vinyl-substituted N,N-dialkyl arylamines to afford nitrogen-containing heterocycles. Our ...mechanistic studies indicate the reaction is initiated by abstraction of an α-hydride from an N-alkyl substituent by B(C6F5)3, which is followed by cyclization, and is concluded by delivery of the hydride to the cyclic cationic intermediate. The dual roles of B(C6F5)3, first as an oxidant and then as a hydride-carrying reductant, have enabled a rare redox-neutral cyclization process between a sp3 carbon and an electron-rich olefin without using a transition metal or an external oxidant.
Background
Wood harvesting and storage (WHS) is a hybrid Nature-Engineering combination method to combat climate change by harvesting wood sustainably and storing it semi-permanently for carbon ...sequestration. To date, the technology has only been purposefully tested in small-scale demonstration projects. This study aims to develop a concrete way to carry out WHS at large-scale.
Results
We describe a method of constructing a wood storage facility, named Wood Vault, that can bury woody biomass on a mega-tonne scale in specially engineered enclosures to ensure anaerobic environments, thus preventing wood decay. The buried wood enters a quasi-geological reservoir that is expected to stay intact semi-permanently. Storing wood in many environments is possible, leading to seven versions of Wood Vault: (1) Burial Mound (Tumulus or Barrow), (2) Underground (Pit, Quarry, or Mine), (3) Super Vault, (4) Shelter, (5) AquaOpen or AquaVault with wood submerged under water, (6) DesertOpen or DesertVault in dry regions, (7) FreezeVault in cold regions such as Antarctica. Smaller sizes are also possible, named Baby Vault. A prototype Wood Vault Unit (WVU) occupies 1 hectare (ha, 100 m by 100 m) of surface land, 20 m tall, stores up to 100,000 m
3
of wood, sequestering 0.1 MtCO
2
. A 1 MtCO
2
y
−1
sequestration rate can be achieved by collecting currently unused wood residuals (WR) on an area of 25,000 km
2
, the size of 10 typical counties in the eastern US, corresponding to an average transportation distance of less than 100 km. After 30 years of operation, such a Wood Vault facility would have sequestered 30 MtCO
2
, stored in 300 WVUs, occupying a land surface of 300 ha. The cost is estimated at $10–50/tCO
2
with a mid-point price of $30/tCO
2
. To sequester 1 GtCO
2
y
−1
, wood can be sourced from currently unexploited wood residuals on an area of 9 Mkm
2
forested land (9 million square kilometers, size of the US), corresponding to a low areal harvesting intensity of 1.1 tCO
2
ha
−1
y
−1
. Alternatively, giga-tonne scale carbon removal can be achieved by harvesting wood at a medium harvesting intensity of 4 tCO
2
ha
−1
y
−1
on 3 Mkm
2
of forest (equivalent to increasing current world wood harvest rate by 25%), or harvest on 0.8 Mkm
2
forest restored from past Amazon deforestation at high harvest intensity, or many combinations of these and other possibilities. It takes 1000 facilities as discussed above to store 1 GtCO
2
y
−1
, compared to more than 6000 landfills currently in operation in the US. After full closure of a Wood Vault, the land can be utilized for recreation, agriculture, solar farm, or agrivoltaics. A more distributed small operator model (Baby Vault) has somewhat different operation and economic constraints. A 10 giga-tonne sequestration rate siphons off only 5% of total terrestrial net primary production, thus possible with WHS, but extreme caution needs to be taken to ensure sustainable wood sourcing.
Conclusions
Our technical and economic analysis shows that Wood Vault can be a powerful tool to sequester carbon reliably, using a variety of wood sources. Most pieces of the technology already exist, but they need to be put together efficiently in practice. Some uncertainties need to be addressed, including how durability of buried wood depends on detailed storage methods and burial environment, but the science and technology are known well enough to believe the practicality of the method. The high durability, verifiability and low-cost makes it already an attractive option in the current global carbon market. Woody biomass stored in Wood Vaults is not only a carbon sink to combat current climate crisis, but also a valuable resource for the future that can be used as biomass/bioenergy and carbon supply. The quantity of this wood utilization can be controlled carefully to maintain a desired amount of CO
2
in the atmosphere to keep the Earth’s climate from diving into the next ice age, acting as a climate thermostat. The CO
2
drawdown time is on the order of 100 years while the ramp-up time is a decade. A sense of urgency is warranted because the CO
2
removal rate is limited by biosphere productivity, thus delayed action means a loss of opportunity. In conclusion, WHS provides a tool for managing our Earth system, which will likely remain forever in the Anthropocene.
Purpose
Microvascular invasion (MVI) is a valuable predictor of survival in hepatocellular carcinoma (HCC) patients. This study developed predictive models using eXtreme Gradient Boosting (XGBoost) ...and deep learning based on CT images to predict MVI preoperatively.
Methods
In total, 405 patients were included. A total of 7302 radiomic features and 17 radiological features were extracted by a radiomics feature extraction package and radiologists, respectively. We developed a XGBoost model based on radiomics features, radiological features and clinical variables and a three-dimensional convolutional neural network (3D-CNN) to predict MVI status. Next, we compared the efficacy of the two models.
Results
Of the 405 patients, 220 (54.3%) were MVI positive, and 185 (45.7%) were MVI negative. The areas under the receiver operating characteristic curves (AUROCs) of the Radiomics-Radiological-Clinical (RRC) Model and 3D-CNN Model in the training set were 0.952 (95% confidence interval (CI) 0.923–0.973) and 0.980 (95% CI 0.959–0.993), respectively (
p
= 0.14). The AUROCs of the RRC Model and 3D-CNN Model in the validation set were 0.887 (95% CI 0.797–0.947) and 0.906 (95% CI 0.821–0.960), respectively (
p
= 0.83). Based on the MVI status predicted by the RRC and 3D-CNN Models, the mean recurrence-free survival (RFS) was significantly better in the predicted MVI-negative group than that in the predicted MVI-positive group (RRC Model: 69.95 vs. 24.80 months,
p
< 0.001; 3D-CNN Model: 64.06 vs. 31.05 months,
p
= 0.027).
Conclusion
The RRC Model and 3D-CNN models showed considerable efficacy in identifying MVI preoperatively. These machine learning models may facilitate decision-making in HCC treatment but requires further validation.
Differences in the bacterial community structure associated with 7 skin sites in 71 healthy people over five days showed significant correlations with age, gender, physical skin parameters, and ...whether participants lived in urban or rural locations in the same city. While body site explained the majority of the variance in bacterial community structure, the composition of the skin-associated bacterial communities were predominantly influenced by whether the participants were living in an urban or rural environment, with a significantly greater relative abundance of Trabulsiella in urban populations. Adults maintained greater overall microbial diversity than adolescents or the elderly, while the intragroup variation among the elderly and rural populations was significantly greater. Skin-associated bacterial community structure and composition could predict whether a sample came from an urban or a rural resident ~5x greater than random.
Wind and solar farms offer a major pathway to clean, renewable energies. However, these farms would significantly change land surface properties, and, if sufficiently large, the farms may lead to ...unintended climate consequences. In this study, we used a climate model with dynamic vegetation to show that large-scale installations of wind and solar farms covering the Sahara lead to a local temperature increase and more than a twofold precipitation increase, especially in the Sahel, through increased surface friction and reduced albedo. The resulting increase in vegetation further enhances precipitation, creating a positive albedo-precipitation-vegetation feedback that contributes ~80% of the precipitation increase for wind farms. This local enhancement is scale dependent and is particular to the Sahara, with small impacts in other deserts.
Background
Understanding the internal anatomy of the liver remains a major challenge in anatomical liver resection. Although virtual hepatectomy and indocyanine green (ICG) fluorescence imaging ...techniques have been widely used in hepatobiliary surgery, limitations in their application for real-time navigation persist.
Objective
The aim of the present study was to evaluate the feasibility and clinical utility of the novel laparoscopic hepatectomy navigation system (LHNS), which fuses preoperative three-dimensional (3D) models with ICG fluorescence imaging to achieve real-time surgical navigation.
Methods
We conducted a retrospective review of clinical outcome for 64 patients who underwent laparoscopic hepatectomy from January 2018 to December 2018, including 30 patients who underwent the procedure using the LHNS (LHNS group) and 34 patients who underwent the procedure without LHNS guidance (Non-LHNS group).
Results
There was no significant difference in preoperative characteristics between the two groups. The LHNS group had a significantly less blood loss (285.0 ± 163.0 mL vs. 391.1 ± 242.0 mL;
P
= 0.047), less intraoperative blood transfusion rate (13.3% vs. 38.2%;
P
= 0.045), and shorter postoperative hospital stay (7.8 ± 2.1 days vs. 10.6 ± 3.8 days;
P
< 0.001) than the Non-LHNS group. There was no statistical difference in operative time and the overall complication rate between the two groups. The liver transection line was clearly delineated by the LHNS in 27 patients; however, the projection of boundary was unclear in 2 cases, and in 1 case, the boundary was not clearly displayed by ICG fluorescence imaging.
Conclusions
We developed the LHNS to address limitations of current intraoperative imaging systems. The LHNS is hopefully to become a promising real-time navigation system for laparoscopic hepatectomy.
The reliable detection and attribution of changes in vegetation growth is a prerequisite for the development of strategies for the sustainable management of ecosystems. This is an extraordinary ...challenge. To our knowledge, this study is the first to comprehensively detect and attribute a greening trend in China over the last three decades. We use three different satellite‐derived Leaf Area Index (LAI) datasets for detection as well as five different process‐based ecosystem models for attribution. Rising atmospheric CO₂concentration and nitrogen deposition are identified as the most likely causes of the greening trend in China, explaining 85% and 41% of the average growing‐season LAI trend (LAIGS) estimated by satellite datasets (average trend of 0.0070 yr⁻¹, ranging from 0.0035 yr⁻¹to 0.0127 yr⁻¹), respectively. The contribution of nitrogen deposition is more clearly seen in southern China than in the north of the country. Models disagree about the contribution of climate change alone to the trend in LAIGSat the country scale (one model shows a significant increasing trend, whereas two others show significant decreasing trends). However, the models generally agree on the negative impacts of climate change in north China and Inner Mongolia and the positive impact in the Qinghai–Xizang plateau. Provincial forest area change tends to be significantly correlated with the trend of LAIGS(P < 0.05), and marginally significantly (P = 0.07) correlated with the residual of LAIGStrend, calculated as the trend observed by satellite minus that estimated by models through considering the effects of climate change, rising CO₂concentration and nitrogen deposition, across different provinces. This result highlights the important role of China's afforestation program in explaining the spatial patterns of trend in vegetation growth.
Background
The septal extension graft is one of the most commonly used grafts in Asian tip plasty techniques. However, the septal extension graft usually induces a hard and immobile nasal tip. The ...purpose of this study was to evaluate the esthetic outcomes of the modified septal extension graft with M-shaped auricular cartilage by three-dimensional anthropometric analysis.
Methods
A total of 36 patients received augmentation rhinoplasty with M-shaped auricular cartilage as septal extension graft combined with silicone implant. Thirteen measurement items were evaluated using three-dimensional anthropometric techniques, and the preoperative and postoperative results were compared.
Results
The majority of patients (91.7%) were satisfied with the postoperative nasal shape. No infection, gross absorption, graft exposure, implant exposure, or implant migration was observed. Compared with the preoperative value, the nasal length, nasal height, nasal depth, nasion height, columella width, nasolabial angle, nasofrontal angle, and nasal depth-nasal width index significantly increased. The nasal width, nasal tip width, and nasal index significantly decreased.
Conclusion
We performed tip plasty with the M-shaped auricular cartilage as modified septal extension graft, achieving a soft and mobile tip with satisfying tip projection in most patients.
Level of Evidence IV
This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors
www.springer.com/00266
.
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