Experimental study on failure evolution mechanism of clastic rock considering cementation and intermediate principal stress

The study of clastic rock failure evolution under true triaxial stress is an important research topic;however,it is rarely studied systematically due to the limitation of monitoring technology.In this study,true triaxial compression tests were conducted on clastic rock specimens to investigate the effect of cementation and intermediate principal stress(s2)on the failure mechanism.The complete stressestrain curves were obtained,while the acoustic emission(AE)was monitored to indirectly evaluate the evo-lution of tensile and shear cracks,and crack evolution under true triaxial compression was imaged in real time by a high-speed camera.The results showed that the deformation and failure characteristics of clastic rock were closely related to the cementation type and intermediate principal stress.On the basis of the distribution characteristics of the ratio of rise time to amplitude(RA)and the average frequency(AF)of AE signals,tensile cracks of the contact cementation specimen propagated preferentially.Meanwhile,the enhancement of specimen cementation promoted the evolution of shear cracks,and the increase inσ_(2)promoted the evolution of tensile cracks.Moreover,the mesoscale cracking mechanism of clastic rock caused by cementation andσ_(2)under true triaxial compression was analyzed.The failure patterns of clastic rock under true triaxial compression were divided into three modes:structure-induced,structure-stress-induced and stress-induced failures.This study confirms the feasibility of high-speed camera technology in true triaxial testing,and has important implications for elucidating the disaster mechanism of deep tunnels in weak rocks.

A rigid true triaxial apparatus for analyses of deformation and failure features of deep weak rock under excavation stress paths

The squeezing scenario in deep weak rock tunnels can hinder underground construction.However,due to the limitations of test technologies at hand,the real excavation stress path cannot be mimicked in the laboratory.Thus,the large deformation mechanism of deep weak rocks still remains unclear.For this,a true triaxial apparatus(TTA)to investigate the mechanical responses of deep weak rock under excavation stress paths in field and reveal the squeezing mechanism of deep tunnels is assembled and developed at Northeastern University,China.The apparatus can perform instantaneous unloading in s3 direction based on electromagnetism technology.In addition,uniform loading and deformation measurements can be carried out based on the proposed linked interlocking clamp and antifriction device,even if the sample has a strong dilatation deformation performance.Next,a bore trepanning is designed to capture noiseless acoustic emission(AE)signals for deep weak rock at a low threshold.Finally,two tests were are conducted using this instrument to preliminarily understand the failure and deformation features of deep weak rock based on fractured marble.The results show that the complete stressestrain curves of fractured marble have the characteristics of low strengths and large deformations,and the larger deformation and the more serious failure occur when the fractured marble enters the post-peak state after excavation.The results show that the developed apparatus is likely to be applicable for deep weak rock engineering.

Magnetic resonance imaging diagnosis of acute Guillain-Barré syndrome in children

The present study examined 24 children with acute Guillain-Barre syndrome using magnetic resonance imaging （MRI） plain scans and fat-suppressed enhanced Tl-weighted imaging （T1WI） scans. Axial MRI plain scans centering on the medullary conus were positive in nine patients （38%）. These displayed variable thickening involving the cauda equina with isointensity on T1WI and isointensity or slight hyperintensity on T2WI. False negatives were obtained in patients with cervical and cranial nerve symptoms. Contrast enhancement of T1WI with fat suppression was positive in all patients in the cauda equina with varied thickening and enhancement centering on the medullary conus. Five patients （36%） were positive in the cervical nerves and 3 patients （50%） were positive in the cranial nerves. These patients had corresponding cervical and cranial nerve symptoms, respectively. Patients with serious clinical symptoms in the lower limbs exhibited obvious involvement of the cauda equina by MRI. Statistical analysis revealed a positive correlation between the extent of enlargement of the cauda equina, centering on the medullary conus, and cerebrospinal fluid protein concentration.

Evaluating nerve guidance conduits for peripheral nerve injuries:a novel normalization method

The peripheral nervous system （PNS） is composed of the nerves and ganglia outside of the brain and spinal cord whose primary function is to connect the central nervous system to the limbs and organs. A peripheral nerve injury （PNI） is damage to the nerves and/or its surrounding tissue. These injuries can affect up to 5% of patients that are hospitalized for trauma （Taylor et al., 2008） and over 50,000 surgical repair procedures are performed annually in the United States alone （Evans, 2001）.

THE HEMODYNAMIC EFFECTS OF THE DOUBLE CHAMBER INTRA-AORTIC BALLOON PUMPING

Our experimental results showed that the effect of the double chamber intra-aortic balloon pumping was better than that of single chamber intraaortic balloon pumping. It significantly improved the hemodynamic parameters andimproved the efficiency of the counterpulsation. The result is consistent with the design of the computer simulation.

RSPSSL:A novel high-fidelity Raman spectral preprocessing scheme to enhance biomedical applications and chemical resolution visualization

Raman spectroscopy has tremendous potential for material analysis with its molecular fingerprinting capability in many branches of science and technology.It is also an emerging omics technique for metabolic profiling to shape precision medicine.However,precisely attributing vibration peaks coupled with specific environmental,instrumental,and specimen noise is problematic.Intelligent Raman spectral preprocessing to remove statistical bias noise and sample-related errors should provide a powerful tool for valuable information extraction.Here,we propose a novel Raman spectral preprocessing scheme based on self-supervised learning(RSPSSL)with high capacity and spectral fidelity.It can preprocess arbitrary Raman spectra without further training at a speed of~1900 spectra per second without human interference.The experimental data preprocessing trial demonstrated its excellent capacity and signal fidelity with an 88%reduction in root mean square error and a 60%reduction in infinite norm(L__(∞))compared to established techniques.With this advantage,it remarkably enhanced various biomedical applications with a 400%accuracy elevation(ΔAUC)in cancer diagnosis,an average 38%(few-shot)and 242%accuracy improvement in paraquat concentration prediction,and unsealed the chemical resolution of biomedical hyperspectral images,especially in the spectral fingerprint region.It precisely preprocessed various Raman spectra from different spectroscopy devices,laboratories,and diverse applications.This scheme will enable biomedical mechanism screening with the label-free volumetric molecular imaging tool on organism and disease metabolomics profiling with a scenario of high throughput,cross-device,various analyte complexity,and diverse applications.

Multi-channel spectral-domain optical coherence tomography using single spectrometer

Multi-channel detection is an effective way to improve data throughput of spectral-domain optical coherence tomography(SDOCT).However,current multi-channel OCT requires multiple detectors,which increases the complexity and cost of the system.We propose a novel multi-channel detection design based on a single spectrometer.Each camera pixel receives interferometric spectral signals from all the channels but with a spectral shift between two channels.This design effectively broadens the spectral bandwidth of each pixel,which reduces relative intensity noise(RIN)by√M times with M being the number of channels.We theoretically analyzed the noise of the proposed design under two cases:shot-noise limited and electrical noise or RIN limited.We show both theoretically and experimentally that this design can effectively improve the sensitivity,especially for electrical noise or RIN-dominated systems.

肝内胆管细胞癌外科治疗疗效分析

目的探讨手术切除治疗肝内胆管细胞癌(intrahepatic cholangiocarcinoma,ICC)的临床疗效及分析影响预后的危险因素。方法回顾性分析2015年1月1日至2021年4月30日于安徽医科大学第一附属医院普外科接受手术切除的ICC患者的临床资料。结果67例获得完整随访,最终纳入本研究中。截止至2022年4月30日,中位随访时间14(1~60)个月,53例(79.1%)肿瘤复发,52例(77.6%)死亡,其中49例(73.1%)死于肿瘤复发,全组1、2、3年累积的无瘤和总体生存率分别为35.6%、19.6%、16.8%和53.7%、32.4%、20.8%。无微血管侵犯组总体生存率显著优于有微血管侵犯组(χ^(2)=5.916,P=0.015)。CA19-9≥1000 U/ml是影响ICC术后无瘤生存时间的独立危险因素。CA19-9≥1000 U/ml、术中失血量≥600 ml、微血管侵犯和肿瘤复发是影响ICC术后总体生存时间的独立危险因素。结论单发ICC肿瘤,当肿瘤直径≤5 cm且考虑无微血管侵犯时,可积极推荐手术切除,能够取得较为满意的手术效果。

Influence of Al/Cu content on grain boundary diffusion in Nd-Fe-B magnet via in-situ observation

The influence of aluminum and copper content in the starting Nd-Fe-B magnet on grain boundary diffusion process(GBDP) was studied by observing the phase transformation behaviors of the magnets in-situ at high temperature. A higher coercivity increment is discovered in the sample with higher AI/Cu despite the fact that its Dy diffusion amount is the same as the other. DSC analysis shows an evident melting behavior in the higher Al/Cu sample. Laser scanning confocal microscopy(LSCM) in-situ characterization shows a large amount of melted intergranular phase spills out to the surface simultaneously at around 600 ℃ in the high Al/Cu sample, while the phase spills out gradually one after another in the range between 623 and680 ℃ in the other sample, which indicates that the intergranular phase can be more easily melted in the sample containing more AI/Cu. The area fraction of matrix phase remarkably shrinks while that of intergranular phase enlarges after LSCM heating, which demonstrates the outer region of the Nd_2 Fe_(14)B grains melt at the temperature of 900 ℃. Electron probe microanalyzer result(EPMA) shows that the Nd and Dy concentrate in edge regions and subsequently mix into the intergranular phase with the melting of the grain edge, while a large amount of AI and Cu in the intergranular phase spill out. Nevertheless, the sample with higher starting AI/Cu still remains higher residual contents after LSCM experiments, and that could probably be the main reason why the high AI/Cu magnet shows smaller coercivity decrement after LSCM experiment. Overall, the increase of AI/Cu in the starting magnet optimizes the Dy distribution and the wettability of intergranular phase, enhancing coercivity increment effect further.

Biopolymer-nanotube nerve guidance conduit drug delivery for peripheral nerve regeneration:In vivo structural and functional assessment

Peripheral nerve injuries account for roughly 3%of all trauma patients with over 900,000 repair procedures annually in the US.Of all extremity peripheral nerve injuries,51%require nerve repair with a transected gap.The current gold-standard treatment for peripheral nerve injuries,autograft repair,has several shortcomings.Engineered constructs are currently only suitable for short gaps or small diameter nerves.Here,we investigate novel nerve guidance conduits with aligned microchannel porosity that deliver sustained-release of neurogenic 4-aminopyridine(4-AP)for peripheral nerve regeneration in a critical-size(15 mm)rat sciatic nerve transection model.The results of functional walking track analysis,morphometric evaluations of myelin development,and histological assessments of various markers confirmed the equivalency of our drug-conduit with autograft controls.Repaired nerves showed formation of thick myelin,presence of S100 and neurofilament markers,and promising functional recovery.The conduit’s aligned microchannel architecture may play a vital role in physically guiding axons for distal target reinnervation,while the sustained release of 4-AP may increase nerve conduction,and in turn synaptic neurotransmitter release and upregulation of critical Schwann cell neurotrophic factors.Overall,our nerve construct design facilitates efficient and efficacious peripheral nerve regeneration via a drug delivery system that is feasible for clinical applications.

Metabolic risk factors associated with sudden cardiac death(SCD)during acute myocardial ischemia

Sudden cardiac death(SCD)is the leading cause of death worldwide.Myocardial ischemia(MI)is the most common underlying causal disorder for SCD.Metabolic risks leading to SCD during acute MI are still not fully understood.Here,using tissue metabolomics,we aimed to investigate myocardial metabolic alterations relevant to SCD events in an acute MI rat model induced by coronary artery ligation(CAL).Thirty-four rats were successfully performed CAL,of which 13 developed lethal ventricular tachyarrhythmia(LVTA)-SCD and 7 developed severe atrioventricular block(AB)-SCD.Fourteen rats that survived within 70 min after the ligation were served as peer controls.The partial least squares-discriminant analysis plots demonstrated clear separations between the SCD rats and controls,indicating obvious differences in myocardial metabolome between these rats.The levels of isoleucine,lactate,glutamate choline,phosphorylcholine,taurine and asparagine in ischemic myocardia were positively associated with LVTA-SCD events;in contrast,the levels of alanine,urea,phenylalanine,linoleic acid,elaidic acid and stearic acid were inversely correlated with LVTA-SCD events.The levels of glutamate and urea were positively and negatively relevant to AB-SCD events,respectively.The dangerous metabolites indicated that lower levels of energy substrates,severe hypoxia,the inhibition of transamination and hyper sympathetic excitement and reactive oxygen species in myocardia were vulnerable to SCD during acute MI.The results suggest fatal metabolic alterations correlated with SCD events during acute MI,which could offer novel clues for the prevention or treatment of acute MI-related SCD.

Intramedullary schwannoma of the upper cervical spinal cord:a case study of identification in pathologic autopsy

Intramedullary schwannoma of the upper cervical spinal cord is rarely reported in forensic medicine.We herein report a case involving a patient who died of compression from an intramedullary schwannoma in the upper cervical spinal cord.A 30-year-old man initially presented with a five-day history of pain in the left chest that progressed to weakening in the left arm.Although the patient was treated with analgesic poultices,he developed inspiratory dyspnoea and died while working the next day without having undergone any medical imaging examination or surgical treatment.Anatomical and histopathological examinations revealed an intramedullary schwannoma in the left cervical spinal cord(C_(3)-C_(5))underneath the spinal nerve root.The cause of death might have been asphyxia secondary to the tumour,which interfered with the nerve function in the respiratory muscles.This finding suggests that an autopsy is essential for pathologists and medicolegists to comprehensively undertake their due obligation to obtain“the first evidence”,especially when there is a lack of directly related evidence.As part of the central nervous system,the spinal cord could be systematically included in a routine pathological autopsy in some cases.

Radiotherapy assisted with biomaterials to trigger antitumor immunity

As an extensively applied therapeutic approach to combat tumors,radiotherapy generates localized ionizing radiation to destruct tumor cells.Despite its importance in clinical oncology,radiotherapy would often cause significant organ toxicity,and its therapeutic effect is limited by tumor hypoxia.Moreover,although abscopal therapeutic effects have occasionally been observed,radiotherapy is still mostly employed as a local treatment method that could hardly control tumor metastases.In recent years,strategies involving biomaterials and nanomedicine have received increasingly high attention to enhance cancer radiotherapy.Beyond sensitizing tumors for radiotherapy via various mechanisms,many biomaterial systems with immune stimulating effects have also been introduced to boost the antitumor immunity post cancer radiotherapy.In this mini-review,we will summarize the progress of different biomaterials and nanomedicine systems in combination with radiotherapy to trigger antitumor immune responses and enhance the efficacy of immunotherapy,and discusses the perspectives and challenges of this research direction aimed at clinical translations.