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BACKGROUND: Gastric cancer (GC) is a significant health problem worldwide, and early detection and accurate diagnosis are crucial for improving patient outcomes. Crawling-type gastric adenocarcinoma is a rare subtype of GC that has unique histopathological and clinical characteristics, and its diagnosis and management can be challenging. This pathological type of GC is also rare. CASE SUMMARY: Here, we report the case of a patient who underwent ordinary endoscopy, narrow-band imaging, and endoscopic ultrasonography intending to determine the extent of tumor invasion and upper abdominal enhanced computed tomography and whether there was tumor metastasis. Then, endoscopic submucosal dissection was performed. After pathological and immunohistochemical examination, the pathological diagnosis was crawling-type gastric adenocarcinoma. This is a very rare and special pathological type of tumor. This case highlights the importance of using advanced endoscopic techniques and pathological examination in diagnosing and managing gastric crawling-type adenocarcinoma. Moreover, the findings underscore the need for continued research and clinical experience in this rare subtype of GC to improve patient outcomes. CONCLUSION: The "crawling-type" GC is a rare and specific tumor pathology. It is difficult to identify and diagnose gliomas via endoscopy. The tumor is ill-defined, with a flat appearance and indistinct borders due to the lack of contrast against the background mucosa. Pathology revealed that the tumor cells were hand-like, so the patient has diagnosed with "crawling-type" gastric adenocarcinoma.
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Although chronic osteomyelitis (COM) affecting the extremities is a frequently occurring disease, the incidence of squamous cell carcinoma (SCC) arising from COM is rare. Consequently, understanding the diagnosis, treatment and prognosis of such a disorder remains limited. In the present study, a case of COM-associated SCC was demonstrated. A 65-year-old woman arrived to the Southern Medical University Nanfang Hospital (Guangzhou, China) with multiple sinus tracts and skin ulcers in the distal part of her left thigh, persisting for over 50 years following an open pierce injury by an ox horn. A local biopsy confirmed the diagnosis of COM-related SCC. Although limb amputation was recommended, the female patient declined initially. Instead, the female patient underwent focused debridement and wide resection of the tumor, followed by local implantation of calcium sulfate beads loaded with vancomycin and gentamycin, and application of a rail fixator. A total of 10 months later, the cancer recurred, affecting the osseous tissue. Subsequently, the patient underwent amputation of the thigh. At the one-year follow-up, the patient showed satisfactory recovery without signs of local recurrence. Despite its rarity, the severity of this disorder should not be underestimated. Personalized treatment strategies must be tailored to individual circumstances.
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Canavanine resistance has been used to analyze mutation rates in the fission yeast Schizosaccharomyces pombe . However, the genetic basis of canavanine resistance in this organism remains incompletely understood. Here, we performed whole genome sequencing on five spontaneously arising canavanine-resistant S. pombe mutants, including the can2-1 mutant isolated in the 1970s. This analysis revealed that three mutants, including can2-1 , experienced terminal deletions of the left arm of chromosome II, leading to the loss of multiple amino acid transporter genes. Interestingly, these three mutants underwent chromosome terminal deletion through distinct mechanisms, including homology-driven translocation, homology-independent chromosome fusion, and de novo telomere addition. Our findings shed new light on the genetic basis of canavanine resistance and mechanisms underlying chromosome terminal deletions in fission yeast.
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OBJECTIVE: To evaluate the clinical and radiological efficacy of a combine of lateral single screw-rod and unilateral percutaneous pedicle screw fixation (LSUP) for lateral lumbar interbody fusion (LLIF) in the treatment of spondylolisthesis. METHODS: Sixty-two consecutive patients with lumbar spondylolisthesis who underwent minimally invasive (MIS)-TLIF with bilateral pedicle screw (BPS) or LLIF-LSUP were retrospectively studied. Segmental lordosis angle (SLA), lumbar lordosis angle (LLA), disc height (DH), slipping percentage, the cross-sectional areas (CSA) of the thecal sac, screw placement accuracy, fusion rate and foraminal height (FH) were used to evaluate radiographic changes postoperatively. Visual analogue scale (VAS) and Oswestry Disability Index (ODI) were used to evaluate the clinical efficacy. RESULTS: Patients who underwent LLIF-LSUP showed shorter operating time, less length of hospital stay and lower blood loss than MIS-TLIF. No statistical difference was found between the 2 groups in screw placement accuracy, overall complications, VAS, and ODI. Compared with MIS-TLIF-BPS, LLIF-LSUP had a significant improvement in sagittal parameters including DH, FH, LLA, and SLA. The CSA of MIS-TLIF-BPS was significantly increased than that of LLIF-LSUP. The fusion rate of LLIF-LSUP was significantly higher than that of MIS-TLIF-BPS at the follow-up of 3 months postoperatively, but there was no statistical difference between the 2 groups at the follow-up of 6 months, 9 months, and 12 months. CONCLUSION: The overall clinical outcomes and complications of LLIF-LSUP were comparable to that of MIS-TLIF-BPS in this series. Compared with MIS-TLIF-BPS, LLIF-LSUP for lumbar spondylolisthesis represents a significantly shorter operating time, hospital stay and lower blood loss, and demonstrates better radiological outcomes to maintain lumbar lordosis, and reveal an overwhelming superiority in the early fusion rate.
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With the promotion of Industry 4.0, which emphasizes interconnected and intelligent devices, several factories have introduced numerous terminal Internet of Things (IoT) devices to collect relevant data or monitor the health status of equipment. The collected data are transmitted back to the backend server through network transmission by the terminal IoT devices. However, as devices communicate with each other over a network, the entire transmission environment faces significant security issues. When an attacker connects to a factory network, they can easily steal the transmitted data and tamper with them or send false data to the backend server, causing abnormal data in the entire environment. This study focuses on investigating how to ensure that data transmission in a factory environment originates from legitimate devices and that related confidential data are encrypted and packaged. This paper proposes an authentication mechanism between terminal IoT devices and backend servers based on elliptic curve cryptography and trusted tokens with packet encryption using the TLS protocol. Before communication between terminal IoT devices and backend servers can occur, the authentication mechanism proposed in this paper must first be implemented to confirm the identity of the devices and, thus, the problem of attackers imitating terminal IoT devices transmitting false data is resolved. The packets communicated between devices are also encrypted, preventing attackers from knowing their content even if they steal the packets. The authentication mechanism proposed in this paper ensures the source and correctness of the data. In terms of security analysis, the proposed mechanism in this paper effectively withstands replay attacks, eavesdropping attacks, man-in-the-middle attacks, and simulated attacks. Additionally, the mechanism supports mutual authentication and forward secrecy. In the experimental results, the proposed mechanism demonstrates approximately 73% improvement in efficiency through the lightweight characteristics of elliptic curve cryptography. Moreover, in the analysis of time complexity, the proposed mechanism exhibits significant effectiveness.
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The purpose of this study was to determine the diagnostic efficacy of Xpert MTB/RIF assay for rapid diagnosis of Tuberculosis (TB) and detection of rifampicin (RIF) resistance in patients suspected of having EPTB, assessing it against traditional culture and drug susceptibility test (DST) by proportional method, and the ability to predict multidrug resistance TB by Xpert MTB/RIF assay. In this study, the Xpert MTB/RIF assay was applied to 1,614 extrapulmonary specimens. Compared with TB culture and Composite Reference Standard (CRS), the Xpert MTB/RIF assay had a high sensitivity and specificity for detection of EPTB. Depending on the culture method or CRS as the standard, sensitivity of the Xpert MTB/RIF assay for detection of MTB in pleural effusion, cerebrospinal fluid, thoracic drainage fluid and throat swabs specimens were lower than that of other specimens. According to the experimental results, we have reason to believe that Xpert MTB/RIF assay is a rapid and simple technique with high sensitivity and specificity for diagnosing EPTB and detecting drug resistance in variety of specimens. Xpert MTB/RIF assay combined with DST maybe identify more cases of multi-drug resistant tuberculosis (MDR-TB).
Subject(s)
Antibiotics, Antitubercular , Mycobacterium tuberculosis , Tuberculosis, Extrapulmonary , Tuberculosis, Multidrug-Resistant , Tuberculosis , Humans , Rifampin/pharmacology , Mycobacterium tuberculosis/genetics , Sensitivity and Specificity , Tuberculosis/diagnosis , Tuberculosis/drug therapy , Tuberculosis, Multidrug-Resistant/diagnosis , Drug Resistance, Bacterial , Antibiotics, Antitubercular/pharmacologyABSTRACT
Molten salt oxidation (MSO) is an advanced method for waste resins treatment; nevertheless, the research about gas product variations of resins under different stoichiometric air feed coefficient (α) is rare. The optimal working condition of hazardous waste disposal is obtained through thermodynamic equilibrium calculation, and the method to improve the treatment efficiency is found to guide the optimization of the actual experiment. In this paper, Fact Sage was used to calculate the oxidation products of cation exchange resins (CERs) at different temperatures and α, focusing on the similarities and differences through the contents of CO, CH4, CO2, and SO2 during the oxidation of CERs, the MSO of CERs, and the theoretical calculation. The results indicated that the gas products of the calculation and reality of the oxidation process of CERs are quite different, while the CO contents of CERs during MSO are close to the calculated values. The main reason for this consequence is that in the oxidation process of CERs, the S in the sulfonic acid group will form thermally stable C-S with the styrene-divinylbenzene skeleton. Moreover, the introduction of carbonate can promote the destruction of C-S and absorb SO2 as sulfate, weakening the influence of C-S on the oxidation products of CERs. The gas chromatograph results indicated that the SO2 content is reduced from 0.66% in the process of CERs oxidation to 0.28% in MSO of CERs. When 1.25 times stoichiometric air feed coefficient is fed, the sulfate content in the carbonate is the highest at 900 °C, which is 23.4%.
Subject(s)
Cation Exchange Resins , Gases , Sodium Chloride , Sodium Chloride, Dietary , Carbonates , OxygenABSTRACT
At the regional scale, substrate properties are the key factors driving litter decomposition rate. In this study, soil temperature was increased by buried heating cables to explore the impacts of climate warming on the physical and chemical properties in branch and leaf of Cunninghamia lanceolata litter. The results showed that after 5 years of soil warming (4 â), the contents of nitrogen (N), phosphorus (P) and water-soluble substance in branch litter increased by 35.2%, 40.8% and 7.6%, while that in leaf litter increased by 41.2%, 45.9% and 5.9%, respectively. The contents of carbon (C), cellulose and C/N in branch litter decreased by 5.1%, 11.6% and 28.8%, and in leaf litter decreased by 5.3%, 11.3% and 33.3%, respectively. Soil warming led to 29.8% increase in specific leaf area (SLA) and 40.7% decrease in tensile strength (LTS) of leaf litter. However, warming did not affect lignin content and pH value in both branch and leaf litter. 13C NMR and infrared spectrum analysis showed that the contents of amino acids, polysaccharides, polyphenols and aliphatic compounds in litter changed significantly after warming. Warming effect differed between litter organs, in that polysaccharides increased significantly only in leaf litter and the increase of amino acids in branch litter was greater than that in leaf litter. Overall, soil warming significantly changed the physical and chemical properties in C. lanceolata branch and leaf litter, which might accelerate the decomposition rate at the initial stage due to the increase of N, P contents and the decrease of LTS, but might decelerate the decomposition rate at the later stage due to an increase of complex polymers content in the litter.
Subject(s)
Cunninghamia , Plant Leaves/chemistry , Soil/chemistry , Carbon/analysis , Amino Acids/analysisABSTRACT
In Schizosaccharomyces pombe, the can1-1 mutation confers resistance to the toxic arginine analog canavanine. This mutation has been assumed to disrupt a gene encoding an arginine transporter. In PomBase, the gene SPBC18H10.16 is currently designated can1. Here, we sequenced the genomes of three can1-1 strains. No mutations were found in SPBC18H10.16. Instead, these strains harbor an R175C mutation in the gene any1 (SPBC18H10.20c). any1 encodes an α-arrestin that acts as a ubiquitin ligase adaptor to downregulate plasma membrane amino acid transporters. Our findings indicate that can1-1 is not a loss-of-function mutation in an amino acid transporter gene, but a possible gain-of-function mutation in a gene encoding a negative regulator of amino acid transporters.
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Spasticity, a common stroke complication, can result in impairments and limitations in the performance of activities and participation. In this study, we investigated the effectiveness of a new dynamic splint on wrist and finger flexor muscle spasticity in chronic stroke survivors, using a randomized controlled trial. Thirty chronic stroke survivors were recruited and randomly allocated to either an experimental or control group; 25 completed the 6-week intervention program. The participants in the experimental group were asked to wear the dynamic splint at least 6 h/day at home, for the entire intervention. The participants in the control group did not wear any splint. All the participants were evaluated 1 week before, immediately, and after 3 and 6 weeks of splint use, with the modified Ashworth scale and the Fugl-Meyer assessment for upper extremity. User experience was evaluated by a self-reported questionnaire after the 6-week intervention. The timed within-group assessments showed a significant reduction in spasticity and improvements in functional movements in the experimental group. We found differences, in favor of the experimental group, between the groups after the intervention. The splint users indicated a very good satisfaction rating for muscle tone reduction, comfort, and ease of use. Therefore, this new splint can be used for at-home rehabilitation in chronic stroke patients with hemiparesis.
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Maneuvering a wheelchair is an important necessity for the everyday life and social activities of people with a range of physical disabilities. However, in real life, wheelchair users face several common challenges: articulate steering, spatial relationships, and negotiating obstacles. Therefore, our research group has developed a head-mounted display (HMD)-based intuitive virtual reality (VR) stimulator for wheelchair propulsion. The aim of this study was to investigate the feasibility and efficacy of this VR stimulator for wheelchair propulsion performance. Twenty manual wheelchair users (16 men and 4 women) with spinal cord injuries ranging from T8 to L2 participated in this study. The differences in wheelchair propulsion kinematics between immersive and non-immersive VR environments were assessed using a 3D motion analysis system. Subjective data of the HMD-based intuitive VR stimulator were collected with a Presence Questionnaire and individual semi-structured interview at the end of the trial. Results indicated that propulsion performance was very similar in terms of start angle (p = 0.34), end angle (p = 0.46), stroke angle (p = 0.76), and shoulder movement (p = 0.66) between immersive and non-immersive VR environments. In the VR episode featuring an uphill journey, an increase in propulsion speed (p < 0.01) and cadence (p < 0.01) were found, as well as a greater trunk forward inclination (p = 0.01). Qualitative interviews showed that this VR simulator made an attractive, novel impression and therefore demonstrated the potential as a tool for stimulating training motivation. This HMD-based intuitive VR stimulator can be an effective resource to enhance wheelchair maneuverability experiences.
Subject(s)
Spinal Cord Injuries , Virtual Reality , Wheelchairs , Biomechanical Phenomena , Female , Humans , MaleABSTRACT
OBJECTIVE: To explore clinical effects of intramedullary nailing through suprapatellar approach with semiextended position in treating tibial fractures. METHODS: From January 2018 to June 2019, 23 patients with tibia fractures were treated with suprapatellar approach intramedullary nailing on knee semiextended position, including 18 males and 5 females, aged from 26 to 67 years old with an average age of (38.5±9.6) years old. Eight patients were tibial proximal fractures, 7 patients were tibial shaft fractures, 6 patients were tibial distal fractures and 2 patients were tibial segmental fractures. Operation time, intraoperative blood loss, complications and fracture healing time were recorded. Range of motivation of knee joint between 3 days and 3 months after operation were compared, Hospital for Special Surgery (HSS) score and visual analogue scale (VAS) were used to evaluate clinical effects. RESULTS: All patients were followed up from 8 to 19 months with an average of (12.3±7.6) months. Operation time was (55.3±5.1) min, intraoperative blood loss was (84.0±8.7) ml. No obvious complications occurred. All patients were achieved bony union at stageâ , fracture healing time ranged from 3 to 8 months with an average of (4.6±1.5) months. Flexion extension range of knee motion at 3 days after operation was (110.4±15.3)°, and increased to (123.7±16.5)° at 3 months after operation (t=6.57, P<0.001). Postoperative VAS at 3 days was (0.22±0.74) scores, and decreased to (0.04±0.20) scores at 3 months after operation (t=1.09, P>0.05). Postoperative HSS score at 6 months was 86.2± 11.5, and 19 got excellent result and 4 good. CONCLUSION: Intramedullary nailing through suprapatellar approach with semiextended position in treating tibia fractureshas advantages of simple operation, less trauma for soft tissue, less pain, rapid recovery of function and less complication. It is especially suitable for patients with tibial multi-segment fracture and multiple fractures of ipsilateral lower limb for safety and simple.
Subject(s)
Fracture Fixation, Intramedullary , Tibial Fractures , Adult , Aged , Bone Nails , Diaphyses , Female , Humans , Male , Middle Aged , Tibia , Tibial Fractures/surgery , Treatment OutcomeABSTRACT
The vigorous development of the Industrial Internet of Things brings the advanced connection function of the new generation of industrial automation and control systems. The Supervisory Control and Data Acquisition (SCADA) network is converted into an open and highly interconnected network, where the equipment connections between industrial electronic devices are integrated with a SCADA system through a Modbus protocol. As SCADA and Modbus are easily used for control and monitoring, the interconnection and operational efficiency between systems are highly improved; however, such connectivity inevitably exposes the system to the open network environment. There are many network security threats and vulnerabilities in a SCADA network system. Especially in the era of the Industrial Internet of Things, any security vulnerability of an industrial system may cause serious property losses. Therefore, this paper proposes an encryption and verification mechanism based on the trusted token authentication service and Transport Layer Security (TLS) protocol to prevent attackers from physical attacks. Experimentally, this paper deployed and verified the system in an actual field of energy management system. According to the experimental results, the security defense architecture proposed in this paper can effectively improve security and is compatible with the actual field system.
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A dynamic splint is superior to traditional static splint, offering more benefits such as reduced spasticity, allowing comfortable stretch, repositioning fingers in extension positions, and increasing hand performance. This paper suggested the development of a dynamic splint based on a pulley rotation with a locking system as a home rehabilitation device to reduce hand spasticity in stroke patients. Moreover, this study consisted of two main activities: simulation using finite element analysis and clinical experimental trials. Eight stroke patients participated in 4 weeks of intervention using the proposed dynamic splint for a combined total of least 3 hours per day at home. Outcome measures included Fugl-Meyer Assessment (FMA) and Modified Modified Ashworth Scale (MMAS) at baseline, 2 weeks, and 4 weeks. After 4 weeks of wearing, participants were also asked to fill out a satisfaction questionnaire. The results showed that wearing this proposed dynamic splint over 4 weeks, the hand function of participants increased significantly(p < 0.05), and the spasticity of the hand muscles decreased significantly(p < 0.05). With an overall rating of 8 out of 10 points, stroke participants had a high level of satisfaction with this home-use dynamic splint. The findings indicated that stroke patients who used this proposed splint showed substantial changes in hand function and reduced hand spasticity.
Subject(s)
Stroke Rehabilitation , Stroke , Hand , Humans , Muscle Spasticity , Rotation , Splints , Stroke/complications , Treatment OutcomeABSTRACT
PURPOSE: Over one billion people with disabilities (PWDs) and older adults with mobility impairment are currently in need of assistive technology devices (ATDs) and only 10% of those population have ordinarily access to them. The need for advancement in mobility-assistive technology is growing to address the gap in ATDs provision globally. The purpose of this review is to identify potential future areas of development and research in mobility-assistive technology. METHOD: Publications were identified using scientific and medical electronic databases. Also, a limited grey literature search was conducted to muster a variety of sources. A combination of keyword search terms was used, corresponding to the medical subject heading (MeSH) terms. RESULTS: A total of 392 articles were identified, of which 75 were selected for detailed review. Twenty-eight articles were identified that met the review's inclusion criteria. Future areas of research for mobility-assistive technology were identified by grouping the publications into four main categories. The findings of this review identified several areas of research and development in ATDs in general and mobility-assistive technology, in particular, with special attention to the importance of engaging users and stakeholders in the process of research and design. CONCLUSIONS: It is apparent that users' needs and priorities vary between regions within countries. The majority of studies were noted to mainly identify consumers' perspectives on a national basis. The authors, therefore, suggest that further research should be conducted on a global level to determine the knowledge and perspectives concerning future research and development needs and priorities in mobility-assistive technologies.Implication for RehabilitationDespite the benefits derived from the use of ATDs, only 10% of people with disabilities have access to them.Increasing access, quality and affordable ATDs in all countries is global demand.Identifying mobility consumers' needs and priorities would help in enhancing their quality of life by translating research into new technologies that meet their environment and culture needs.Users' involvement in research and design process is a crucial approach to re-shape the future research agenda.
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Disabled Persons , Self-Help Devices , Aged , Humans , Quality of Life , ResearchABSTRACT
BACKGROUND Clear cell sarcoma (CCS) of soft tissue, or malignant melanoma of soft parts, is a rare disease. We aimed to identify prognostic factors linked to patient survival in CCS by analyzing demographic and clinical features using the Surveillance, Epidemiology, and End Results (SEER) database. This study aimed to identify prognostic factors associated with CCS that would be of clinical value. MATERIAL AND METHODS We collected data from patients diagnosed with CCS between 1973 and 2009 from the SEER database. The Kaplan-Meier method and Cox regression analysis were performed to identify prognostic factors for patient survival. RESULTS A total of 175 patients with CCS were identified from the SEER database. The 5-year survival rate was 62.9%, and the 10-year survival rate was 51.3%. Patients with CCS with local stage, and with tumor size ≤3 cm were more likely to have good survival rates. CONCLUSIONS The findings from this study showed that the identifiable prognostic factors in patients with CCS were stage and tumor size. Local stage and tumor size ≤3 cm were favorable prognostic factors for patient survival in CCS.
Subject(s)
Databases as Topic , Population Surveillance , SEER Program , Sarcoma, Clear Cell/epidemiology , Adult , Disease-Free Survival , Female , Humans , Incidence , Kaplan-Meier Estimate , Male , Middle Aged , Multivariate Analysis , Prognosis , Risk Factors , Sarcoma, Clear Cell/mortality , Survival Analysis , Survival Rate , Tumor BurdenABSTRACT
We examined the effects of warming (+5 â) and reduced natural precipitation (-50%) on nutrient status and physiological indices of Cunninghamia lanceolata seedlings during winter and summer in subtropical China. The results showed that seasonal changes in temperature and precipitation caused the seasonal differences in plant nutrient contents and metabolites levels. Contents of carbon, nitrogen, phosphorus, and potassium in leaves in winter were significantly higher than those in summer. In summer, reduced precipitation and warming had no significant effects on antioxidant enzyme activities in C. lanceolata leaves. In winter, superoxide dismutase and peroxidase activities in the leaves significantly decreased with reduced precipitation by 20.7% and 17.8%. Additionally, in winter, warming treatment significantly increased non-enzymatic ascorbic acid content by 132.5%. Carbon content decreased, whereas proline accumulation and nitrogen content increased under stress induced by combined warming and reduced precipitation in winter. However, carbon content increased by 3.3% under the treatment of simultaneous warming and reduced precipitation in summer. In addition, combined warming and reduced precipitation had no significant effects on the antioxidant system irrespective of the season. In conclusion, the adaptation mechanism of C. lanceolata to warming in summer might be different from that in winter. The changes in nutrient contents in C. lanceolata leaves were more sensitive to stress induced by combined warming and reduced precipitation. Nutrient demand and supply and seasonal changes in plant responses under climate change scenarios should be considered for better managing forest plantations and improving plant productivity.
Subject(s)
Cunninghamia , China , Nutrients , Seasons , SeedlingsABSTRACT
It is hard to predict the response of soil organic matter (SOM) to global climate change due to its heterogenous chemical structure. With the development of molecular techniques to identify the structure, sources and stages of SOM degradation, long-standing questions regarding the composition and stability of SOM might be resolved. To investigate the effects of changes in precipitation patterns on the stability of SOM, we analyzed the specific compositions and extent of degradation of SOM using biomarkers, in a young Cunninghamia lanceolata plantation after reducing 50% of precipitation (P) for two years. The results showed that precipitation reduction (P-treatment) significantly reduced the levels of free lipids. Relative to control (CT), P-treatment decreased short-chain n-alkanoic acids (C16-18) and terpenoids and steroids by 62.8% and 19.1%, respectively. However, P-treatment did not significantly change the concentrations of other aliphatic compounds. Although there was no observable difference in the total lignin content between treatments, P-treatment significantly reduced the acid to aldehyde ratios for syringyl [(Ad/Al)s] and vanillyl [(Ad/Al)v]. Thus, the labile compositions of SOM were accelerated to decomposition under rainfall pattern change. Although the recalcitrant compositions (lignin) were relatively stable, their long-term stability should be further monitored.
Subject(s)
Climate Change , Cunninghamia , Soil/chemistry , Agriculture , Carbon , Lignin , RainABSTRACT
Soil soluble carbon and nitrogen play important roles in soil carbon and nutrient cycles and are highly sensitive to climate change, as they can be directly used by microorganisms. We used Tension Lysimeter to collect soil solution in 50% precipitation exclusion (P) and warming (5 â) plus 50% precipitation exclusion (WP) treatments in a 2 year-old Cunninghamia lanceolata plantation in subtropics, to examine the effects of precipitation and temperature on soil soluble carbon and nitrogen concentrations in soil profile. Results showed that neither P treatment nor WP treatment changed seasonal dynamics of soil dissolved organic carbon (DOC) concentration, with maximum value at October among all treatments. DOC concentration was increased in both P and WP treatments in the whole soil profile, especially in 60 cm soil depth. Compared with the control, DOC concentration was increased by 30.4%-88.7% and 32.8%-137.6% in P and WP treatments, respectively, with the most obvious difference being found in October. DOC concentration was decreased with the increases of soil depth in the control, but no significant difference among different soil layers were found in P and WP treatments. NO3--N concentration was increased by 221.1%-931.0% in WP treatment. Therefore, precipitation reduction might increase losses of C and N from soil solution in subtropical forest, due to improvement of soil permeability by the increases of fine roots grown into deep soil, which might stimulate soil microorganism activities and soil organic matter decomposition. Furthermore, warming would exacerbate the risk of C and N losses.
Subject(s)
Carbon/chemistry , Cunninghamia , Nitrogen/chemistry , Soil/chemistry , Agriculture , Forests , RainABSTRACT
Hydroformylation of 1,2-disubstituted alkenes usually occurs at the α position of the directing heteroatom such as oxygen atom and nitrogen atom. By contrast, to achieve hydroformylation on the ß position of the heteroatom is a tough task. Herein, we report the asymmetric rhodium-catalyzed hydroformylation of 1,2-disubstituted alkenylsilanes with excellent regioselectivity at the ß position (relative to the silicon heteroatom) and enantioselectivity. In a synthetic sense, we achieve the asymmetric hydroformylation on the ß position of the oxygen atom indirectly by using the silicon group as a surrogate for the hydroxyl. Density functional theory (DFT) calculations are carried out to examine energetics of the whole reaction path for Rh/YanPhos-catalyzed asymmetric hydroformylation and understand its regioselectivity and enantioselectivity. Our computational study suggests that the silicon group can activate the substrate and is critical for the regioselectivity.