A case study of blasting vibration attenuation based on wave component characteristics

A typical blasting vibration wave is a composite wave,and its attenuation law is affected by the type of dominant wave component.The purpose of the present study is to establish an attenuation equation of the peak particle velocity(PPV),taking into account the attenuation characteristics of P-,S-and R-waves in the blasting vibration wave.Field blasting tests were carried out as a case to specifically apply the proposed equation.In view of the fact that the discrete properties of rock mass will inevitably cause the uncertainty of blasting vibration,we also carried out a probability analysis of PPV uncertainty,and introduced the concept of reliability to evaluate blasting vibration.The results showed that the established attenuation equation had a higher prediction accuracy,and can be considered as a promising equation implemented on more complex sites.The adopted uncertainty analysis method can comprehensively take account of the attenuation law of blasting vibration measured on site and discrete properties of rock masses.The obtained distribution of the PPV uncertainty factor can quantitatively evaluate the reliability of blasting vibration,which is a powerful and necessary supplement to the PPV attenuation equation.

Performance optimization of scintillator neutron detectors for EMD in CSNS

Chinese Spallation Neutron Source(CSNS) has successfully produced its first neutron beam in 28th August 2017. It has been running steadily from March, 2018. According to the construction plan, the engineering materials diffractometer(EMD) will be installed between 2019–2023. This instrument requires the neutron detectors with the cover area near3 m2in two 90° neutron diffraction angle positions, the neutron detecting efficiency is better than 40%@1A, and the spatial resolution is better than 4 mm×200 mm in horizontal and vertical directions respectively. We have developed a onedimensional position-sensitive neutron detector based on the oblique6Li F/Zn S(Ag) scintillators, wavelength shifting fibers,and Si PMs(silicon photomultipliers) readout. The inhomogeneity of the neutron detection efficiency between each pixel and each detector module, which caused by the inconsistency of the wave-length shifting fibers in collecting scintillation photons, needs to be mitigated before the installation. A performance optimization experiment of the detector modules was carried out on the BL20(beam line 20) of CSNS. Using water sample, the neutron beam with Φ5 mm exit hole was dispersed related evenly into the forward space. According to the neutron counts of each pixel of the detector module, the readout electronics threshold of each pixel is adjusted. Compared with the unadjusted detector module, the inhomogeneity of the detection efficiency for the adjusted one has been improved from 69% to 90%. The test result of the diffraction peak of the standard sample Si showed that the adjusted detector module works well.

Flow Control for a Two-Stage Proportional Valve with Hydraulic Position Feedback

The current research mainly focuses on the flow control for the two-stage proportional valve with hydraulic position feedback which is named as Valvistor valve.Essentially,the Valvistor valve is a proportional throttle valve and the flow fluctuates with the change of load pressure.The flow fluctuation severely restricts the application of the Valvistor valve.In this paper,a novel flow control method the Valvistor valve is provided to suppress the flow fluctuation and develop a high performance proportional flow valve.The mathematical model of this valve is established and linearized.Fuzzy proportional-integral-derivative(PID)controller is adopted in the closed-loop flow control system.The feedback is obtained by the flow inference with back-propagation neural network(BPNN)based on the spool displacement in the pilot stage and the pressure differential across the main orifice.The results show that inference with BPNN can obtain the flow data fast and accurately.With the flow control method,the flow can keep at the set point when the pressure differential across the main orifice changes.The flow control method is effective and the Valvistor valve changes from proportional throttle valve to proportional flow valve.For the developed proportional flow valve,the settling time of the flow is very short when the load pressure changes abruptly.The performances of hysteresis,linearity and bandwidth are in a high range.The linear mathematical model can be verified and the assumptions in the system modeling is reasonable.

Intensity-modulated radiotherapy for breast cancer:a systematic review

Objective:The aim of this study was to assess the long-term effect of breast conservation with breast intensitymodulated radiotherapy (IMRT) for early-stage breast cancers.Methods:Pub Med,EMBASE,Cochrane Library,Chinese Biomedical Literature Database were searched to identify relevant original published trails,and the references of eligible studies were manually screened.Randomized controlled trails reported in any language,comparing breast IMRT with conventional radiotherapy (RT) in patients with early-stage breast cancer were eligible for inclusion.Two investigators independently assessed the quality of included trials and extracted data.The RevMan 5.0 software was used for statistical analysis.Results:Four trials involving 1440 patients were included.The results showed that in the IMRT group,the occurrence of acute moist dermatitis,the edema of the mammary gland and the occurrence of hyperpigmentation were lower than those of RT group,the pooled risk ratio value and 95% confidence interval were 0.28 (0.17-0.48),0.03 (0.00-0.21) and 0.06 (0.02-0.15) respectively.The use of IMRT did not correlate with pain and quality of life,but the presence of moist desquamation did significantly correlate with pain and reduced quality of life.Conclusion:The currently available evidence showed that IMRT significantly reduces the occurrence of moist acute dermatitis anywhere in the breast and alleviates the suffering of patients and improves the quality of life of patients.Future large-scale,high-quality,double-blind trials are needed.

Comparison of Clinical Outcomes of Cortical Bone Trajectory and Traditional Pedicle Screw Fixation in Posterior Lumbar Interbody Fusion

Posterior lumbar interbody fusion (PLIF) is a common surgical procedure and widely used in the treatment of lumbar degenerative disc disorders. Traditionally, posterior lumbar interbody fusion is done by using the traditional pedicle screw (PS) which offers great advantages, but at the same time it has some disadvantages which include the risk of superior facet joint violation and muscle damage. Recently, an alternative method of screw insertion via cortical bone trajectory (CBT) has been invented which has less invasive process and can be placed without the drawbacks associated with the traditional pedicle screw. However, it has to remain an interest whether CBT will provide similar or greater clinical outcomes compared to PS in PLIF. So the main aim of this review is to compare the clinical outcomes of cortical bone trajectory and traditional pedicle screw fixation in posterior lumbar interbody fusion based on the articles published on this topic. Compared to the traditional pedicle screw fixation, PLIF with CBT has similar clinical outcome based on pain intensity, ODI status and JOA score, as well as similar fusion rate and radiological evaluated complication such as loosening of screw. In addition PLIF with CBT has advantages of less facet joint violation, less blood loss, less intraoperative muscle damage and perioperative pain. On the basis of this study, we can suggest that PLIF with CBT can be considered as a reasonable alternative to PS in PLIF.

Radiotherapy combined with surgical treatment for gastric cancer:a meta-analysis

Objective:We carried out a meta-analysis to assess the effectiveness and safety of radiotherapy combined with surgery for gastric cancer.Methods:Randomized Clinical Trials (RCTs) in which radiotherapy (preoperative,intraoperative and postoperative),was compared with surgery alone in resectable gastric cancer were identified by searching Cochrane Library (Issue 2,2009),PubMed (Jan 1966-Jun 2009),EMBASE (Jan 1974-Jun 2009),Chinese Biomedical Literature Database (Jan 1978-Jun 2009),Chinese Science and Technology Periodicals Database (Jan 1989-Jun 2009),China National Knowledge Infrastructure (Jan 1994-Jun 2009) and Wanfang database (Jan 1997-Jun 2009) in English and Chinese languang.Two researchers assessed the quality of included randomized controlled trials (RCT) extracted data independently.The RevMan 5.0 software was used for meta-analysis.Our researchers assessed the quality of included randomized controlled trials (RCT) extracted data independently.The RevMan 5.0 software was used for meta-analysis.Results:Nine randomized controlled trials of 1 548 patients were selected for meta-analysis.Five randomized controlled trials were related with comparison of preoperative radiotherapy plus surgery with single surgery.Two randomized controlled trials were the comparative studies between surgery plus postoperative and single surgery.The meta-analysis results showed that:(1) compared with surgery alone,preoperative radiotherapy combined with surgery can increase 3 years (OR=1.78;95% CI 1.14-2.78,P=0.01),5 years (OR=1.67;95% CI 1.22-2.29,P=0.001),10 years (OR=1.64;95% CI 1.03-2.60,P=0.04) survival rate and resection rate (OR=2.15;95% CI 1.31-3.54,P=0.003);reduce the of tumor recurrence rate (OR=0.59;95% CI 0.37-0.92,P=0.02) and metastasis rate (OR=0.44;95% CI 0.27-0.73,P=0.001);(2) The tumor recurrent rates (OR=0.19,95% CI 0.03-1.14,P=0.07) and tumor metastasis rate (OR=0.09;95% CI 0.00-1.77,P=0.11) had no difference between single surgery group and peri-operative radiotherapy plus surgery group;(3) Postoperative radiotherapy compared with surgery alone had no significant effects on 1 year (OR=0.83;95% CI 0.60-1.15,P=0.26) and 3 years (OR=0.75;95% CI 0.51-1.11,P=0.15) survival rate compared with single surgery,but the 5-year survival rates (OR=0.57;95% CI 0.34-0.95,P=0.03) of the patients who received surgery alone was higher than those who received combined therapy.No difference of the tumor recurrence rate (OR=0.59;95% CI 0.33-1.05,P=0.07),tumor metestasis rate (OR=0.90;95% CI 0.51-1.59,P=0.71) and anastomotic leak (OR=0.98;95% CI 0.25-3.65,P=0.98) were observed between the two groups.Conclusion:Preoperative radiotherapy combined surgery is more rational and effective than surgery alone of gastric cancer.However,in terms of the clinical effects of perioperarive or postoperative radoiotherapy combined with surgery,much multicenter,largescale,high-quality,double-blind and rigorously designed studies would be needed than currently available in the future.

Results of Treating Vertebral Metastases by Percutaneous Vertebroplasty Combined with Interventional Chemotherapy

OBJECTIVE Vertebral metastases are a common manifestation in patients with advanced cancer and treatment is often ineffective. This study was conducted to explore the efficacy of treating vertebral metastases by percutaneous vertebroplasty （PVP） combined with interventional chemotherapy. METHODS Seventy-five patients with vertebral metastases （42 men, 33 women; ages 31-76 years） were divided into 2 groups： 39 cases were treated by PVP combined with chemotherapy （VPCC group）, and 36 cases were treated by PVP alone （VP group）. All procedures were guided by computed tomography （CT） scanning. The results and complications were evaluated by a questionnaire regarding pain and routine follow-up. RESULTS The response rate was significantly higher in the VPCC group than in the VP group （93.0% vs 74.4%, P〈0.05）; total response rates for the VPCC and VP groups were 25.6% and 10.3% respectively. A common complication related to VPCC was transient aggravating pain. CONCLUSION PVP may ameliorate pain, and consolidate the vertebrae of patients with vertebral metastases. Its short-term effect may be enhanced by adding drugs into the bone cement.

PCR Detection and Sequence Analysis of Torque Teno Sus Virus Strains from Guangdong Province

[Objective] Torque teno virus （TIT） is a novel virus with negative single-strand DNA discovered in recent years, which is ubiquitous and nonpatho- genie. Torque teno sus virus （TrsuV） is widely prevalent in swine populations, which is considered to be associated with some diseases such as post-weaning multi- systemic wasting syndrome （PMWS）. This study aimed to provided data for epidemiology of Tl＇suV in Guangdong Province. [Method] PCR primers were synthe- sized based on untranslated region （UTR） segment of TYsuV genome, to conduct PCR detection of 14 swine serum samples from two swine farms in Guangdong Province. A total of four PCR products of TrsuV1 and TrsuV2 from two swine farms were selected for cloning, sequencing and analysis. [ Result] Ten TrsuVl pos- itive samples （71% ） and eight TrsuV2 positive samples （57%） were obtained by PCR, including five double-positive samples （36%）. Sequence analysis of PCR products and reference strains showed that the UTR segments of samples GDTI-1 and GDT1-2 were both 305 bp, sharing 90.2% -95.1% similarity with Tl＇suVl reference strain, and the UTR segments of samples GDT2-1 and GDT2-2 were respectively 259 bp and 248 bp, sharing 67.3% - 100% similarity with TrsuV2 refer- ence strain. [ Conclusion] These results conformed that there are at least two types of Tl＇suV in Guangdong Province, with relatively high detection rates in some swine farms. Despite the putative harmlessness of Tl＇suV, the public health significance of TTsuV is noticeable due to its potential pathogenicity.

A novel biomimetic trabecular bone metal plate for bone repair and osseointegration

Fracture is one of the most common traumatic diseases in clinical practice,and metal plates have always been the first choice for fracture treatment because of their high strength.However,the bone plates have high elastic modulus and do not match the biomechanics of human bone,which adversely affects callus formation and fracture healing.Moreover,the complex microenvironment in the human body can induce corrosion of metallic materials and release toxic ions,which reduces the biocompatibility of the bone plate,and may necessitate surgical removal of the implant.In this study,tantalum(Ta)was deposited on porous silicon carbide(SiC)scaffolds by chemical vapor deposition technology to prepare a novel porous tantalum(pTa)trabecular bone metal plate.The function of the novel bone plate was evaluated by implantation in an animal fracture model.The results showed that the novel bone plate was effective in fracture fixation,without breakage.Both X-ray and microcomputed tomography analysis showed indirect healing by both pTa trabecular bone metal plates and titanium(Ti)plates;however,elastic fixation and obvious callus formation were observed after fixation with pTa trabecular bone metal plates,indicating better bone repair.Histology showed that pTa promoted the formation of new bone and integrated well with the host bone.Therefore,this novel pTa trabecular bone metal plate has good prospects for application in treating fractures.

Advanced cryopreservation engineering strategies:the critical step to utilize stem cell products

With the rapid development of stem cell-related therapies and regenerative medicine,the clinical application of stem cell products is on the rise.However,ensuring the effectiveness of these products after storage and transportation remains a challenge in the transformation to clinical trials.Cryopreservation technology allows for the long-term storage of cells while ensuring viability,making it a top priority for stem cell preservation.The field of cryopreservationrelated engineering technologies is thriving,and this review provides an overview of the background and basic principles of cryopreservation.It then delves into the main bioengineering technologies and strategies used in cryopreservation,including photothermal and electromagnetic rewarming,microencapsulation,and synergetic ice inhibition.Finally,the current challenges and future prospects in the field of efficient cryopreservation of stem cells are summarized and discussed.

Guest Editors'Words

This special issue focuses on the challenges facing the Chinese economy and the global economy in a changing environment.These challenges include trade conflicts,financial instability,geopolitical risks of international investment,monetary policy spillovers,and innovations.The general theme is that policymakers should adjust to this new environment to better cope with the risks and challenges.Moreover,international cooperation has become particularly important in this new era.This special issue consists of eight papers addressing these challenges and the policy choices.

IL-25 blockade inhibits metastasis in breasl cancer

Metastasis is the leading cause of death in breast cancer patients. However, the mechanisms underlying metasta- sis are not well understood and there is no effective treatment in the clinic. Here, we demonstrate that in MMTV- PyMT, a highly malignant spontaneous breast tumor model, IL-25 （also called IL-17E） was expressed by tumor- infiltrating CD4＋ T cells and macrophages. An IL-25 neu- tralization antibody, while not affecting primary tumor growth, substantially reduced lung metastasis. Inhibition of IL-25 resulted in decreased type 2 T cells and macro- phages in the primary tumor microenvironments, both reported to enhance breast tumor invasion and subse- quent metastasis to the lung. Taken together, our data suggest IL-25 blockade as a novel treatment for metastatic breast tumor.

Pathogen-associated T follicular helper cell plasticity is critical in anti-viral immunity

T follicular helper(Tfh)cells are critical in providing help for B cells in the germinal center reaction.Tfh cell plasticity,especially with regard to their expression of effector Th cytokines,has been described,but lacks in-depth analysis with genetic approaches.In this study,we systemically compared transcriptomic profiles of Tfh cells derived from various types of immune responses and found gene clusters corresponding to effector Th cells were differentially induced in response to pathogens or immune responses.Of special interest,a subset of Tfh cells producing IFN-γwas generated in an influenza virus infection,partially dependent on the innate cytokine IL-12.Lineage-tracing mouse model revealed unique developmental regulation of IFN-γ~+Tfh cells,while selective ablation of these cells impaired the induction of Ig G2c~+germinal center B cells and the control of influenza infection.These results indicate that pathogen-associated Tfh cell plasticity is necessary for host immunity,which has implications in vaccine design.

Preparation and corrosion protection performance of a pulse co-deposited Ni/Co/SiO_(2) hydrophobic composite coating

Ni/Co/SiO_(2) hydrophobic coatings were fabricated by embedding SiO_(2) nanoparticles into Ni/Co coatings using pulsed electrodeposition,followed by a liquid-phase hydrophobic treatment.Microstructure and morphology analysis of the composite coatings revealed that the SiO_(2) nanoparticles were homogenously distributed in the Ni/Co coating,and the surfaces of the samples were close-grained without crack.Furthermore,the SiO_(2) nanoparti-cles in the coating formed micro-nano structures on its surface,such that the contact angle reached 125°following the hydrophobic modification.The surface of the hydrophobic coating was found to be abrasion resistant and ex-hibited long-term stability in water.The corrosion inhibition efficiency of the Ni/Co/SiO_(2) hydrophobic coatings on a Q235 carbon steel substrate in simulated seawater solution reached 98.6%,indicating optimal anti-corrosion performance.

Unsteady magnetic reconnection in non-periodic multiple current sheets

The process of magnetic reconnection in non_periodic three_layer current sheets is studied numerically by using two_dimensional magnetohydrodynamic simulation. The results show that unlike periodic current sheets, it is complex unsteady magnetic reconnection. It may be important for solar flare and corona heating.