A theoretical study of the signal enhancement mechanism of coaxial DP-LIBS

In the field of dual-pulse laser-induced breakdown spectroscopy(DP-LIBS)research,the pursuit of methods for determining pulse intervals and other parameters quickly and conveniently in order to achieve optimal spectral signal enhancement is paramount.To aid researchers in identification of optimal signal enhancement conditions and more accurate interpretation of the underlying signal enhancement mechanisms,theoretical simulations of the spatiotemporal processes of coaxial DP-LIBS-induced plasma have been established in this work.Using a model based on laser ablation and two-dimensional axisymmetric fluid dynamics,plasma evolutions during aluminum–magnesium alloy laser ablation under single-pulse and coaxial dualpulse excitations have been simulated.The influences of factors,such as delay time,laser fluence,plasma temperature,and particle number density,on the DP-LIBS spectral signals are investigated.Under pulse intervals ranging from 50 to 1500 ns,the time evolutions of spectral line intensity,dual-pulse emission enhancement relative to the single-pulse results,laser irradiance,spatial distribution of plasma temperature and species number density,as well as laser irradiance shielded by plasma have been obtained.The study indicates that the main reason behind the radiation signal enhancement in coaxial DP-LIBS-induced plasma is attributed to the increased species number density and plasma temperature caused by the second laser,and it is inferred that the shielding effect of the plasma mainly occurs in the boundary layer of the stagnation point flow over the target surface.This research provides a theoretical basis for experimental research,parameter optimization,and signal enhancement tracing in DP-LIBS.

Regeneration of the heart:f rom molecular mechanisms to clinical therapeutics

Heart injury such as myocardial infarction leads to cardiomyocyte loss,fibrotic tissue deposition,and scar formation.These changes reduce cardiac contractility,resulting in heart failure,which causes a huge public health burden.Military personnel,compared with civilians,is exposed to more stress,a risk factor for heart diseases,making cardiovascular health management and treatment innovation an important topic for military medicine.So far,medical intervention can slow down cardiovascular disease progression,but not yet induce heart regeneration.In the past decades,studies have focused on mechanisms underlying the regenerative capability of the heart and applicable approaches to reverse heart injury.Insights have emerged from studies in animal models and early clinical trials.Clinical interventions show the potential to reduce scar formation and enhance cardiomyocyte proliferation that counteracts the pathogenesis of heart disease.In this review,we discuss the signaling events controlling the regeneration of heart tissue and summarize current therapeutic approaches to promote heart regeneration after injury.

Compression techniques of mechanical vibration signals based on optimal sparse representations

This paper presents the result of an experimental study on the compression of mechanical vibration signals. The signals are collected from both rotating and reciprocating machineries by the accelerometers and a data acquisition （DAQ） system. Four optimal sparse representation methods for compression have been considered including the method of frames （ MOF）, best orthogonal basis （ BOB）, matching pursuit （MP） and basis pursuit （BP）. Furthermore, several indicators including compression ratio （CR）, mean square error （MSE）, energy retained （ER） and Kurtosis are taken to evaluate the performance of the above methods. Experimental results show that MP outperforms other three methods.

Flexible piezoelectret film sensor for noncontact mechanical signal capture by multiple transmission media

Mechanical signal capture without physical contact has emerged as a highly promising research field and attracted tremendous attention due to its prosperous applications in household medical care,lifestyle monitoring and remote operation,offering users high level of safety,convenience and comfort.Moreover,noncontact sensing is ideal to maximize the immersive user experience in the human–machine interaction(HMI),eliminating interference to human activities and mechanical fatigue to the sensor,simultaneously.Herein,we report a self-powered flexible sensor integrated with irradiation cross-linked polypropylene(IXPP)piezoelectret film for noncontact sensing,featuring multi-functions to detect mechanical signals transmitted through solid,liquid and gaseous media and would facilitate their versatile practical applications.The folded-structure configuration of the sensor facilitates the improvement of the noncontact sensing sensitivity.For solid media,such as the rectangular wooden stick used in this study,the sensor can detect mechanical stimulus exerted at a distance of 100 cm.A system detection sensitivity up to 57 pC/kPa with a low detection limit of 0.6 kPa is achieved at a noncontact distance of 10 cm.Even when partly or completely immersed in water,the sensor effectively traces movement signals of human bodies underwater,demonstrating great advantages for non-inductive aquatic fitness training monitoring.Furthermore,due to the low acoustic impedance of piezoelectret film,speech recognition through gaseous medium is also achieved.We further introduce application demonstrations of the developed film sensors to monitor exercise postures and physiological signals without direct contact between human body and the sensor,displaying great potential to be incorporated into future smart electronics.This study commendably expands the application scope of piezoelectret materials,which will have profound implications for exploring novel intelligent human–machine interactions.

Progresses of studies on acupuncture and pain signals transduction mechanisms in complete Freund's adjuvant arthritis

Advances of studies on the acupuncture and pain signal transduction mechanisms in complete Freud＇s adjuvant arthritis are reviewed from the three aspects, the first messenger of modulating pain signals and the related receptors, the second messenger of modulating pain signals and other factors possibly involved in modulation of pain signal transduction, etc. It is held that modulation of acupuncture for pain signals is a comprehensive course involved in multi-channels, multi-levels, multi-links, and in future, acupuncture analgesic mechanisms for Freud＇s adjuvant arthritis will be more deeply studied by use of more new techniques and new methods.

Signaling Mechanisms in Pattern-Triggered Immunity （PTI）

In nature, plants constantly have to face pathogen attacks. However, plant disease rarely occurs due to efficient immune systems possessed by the host plants. Pathogens are perceived by two different recognition systems that initiate the so-called pattern-triggered immunity （PTI） and effector-triggered immunity （ETI）, both of which are accompanied by a set of induced defenses that usually repel pathogen attacks. Here we discuss the complex network of signaling pathways occurring during PTI, focusing on the involvement of mitogen-activated protein kinases.

Dynamic resistance exercise increases skeletal muscle-derived FSTL1 inducing cardiac angiogenesis via DIP2A-Smad2/3 in rats following myocardial infarction

Purpose:The aim of this study was to investigate the potential of dynamic resistance exercise to generate skeletal muscle-derived follistatin like-1(FSTL1),which may induce cardioprotection in rats following myocardial infarction(MI)by inducing angiogenesis.Methods:Male,adult Sprague-Dawley rats were randomly divided into 5 groups(n=12 in each group):sham group(S),sedentary MI group(MI),MI+resistance exercise group(MR),MI+adeno-associated virus(AAV)-FSTL1 injection group(MA),and MI+AAV-FSTL1 injection+resistance exercise group(MAR).The AAV-FSTL1 vector was prepared by molecular biology methods and injected into the anterior tibialis muscle.The MI model was established by ligation of the left anterior descending coronary artery.Rats in the MR and MAR groups underwent 4 weeks of dynamic resistance exercise training using a weighted climbing-up ladder.Heart function was evaluated by hemodynamic measures.Collagen volume fraction of myocardium was observed and analyzed by Masson’s staining.Human umbilical vein vessel endothelial cells culture and recombinant human FSTL1 protein or transforming growth factor-b receptor 1(TGFbR1)inhibitor treatment were used to elucidate the molecular signaling mechanism of FSTL1.Angiogenesis,cell proliferation,and disco interacting protein 2 homolog A(DIP2A)location were observed by immunofluorescence staining.The expression of FSTL1,DIP2A,and the activation of signaling pathways were detected by Western blotting.Angiogenesis of endothelial cells was observed by tubule experiment.One-way analysis of variance and Student’s t test were used for statistical analysis.Results:Resistance exercise stimulated the secretion of skeletal muscle FSTL1,which promoted myocardial angiogenesis,inhibited pathological remodeling,and protected cardiac function in MI rats.Exercise facilitated skeletal muscle FSTL1 to play a role in protecting the heart.Exogenous FSTL1 promoted the human umbilical vein vessel endothelial cells proliferation and up-regulated the expression of DIP2A,while TGFbR1 inhibitor intervention down-regulated the phosphorylation level of Smad2/3 and the expression of vascular endothelial growth factor-A,which was not conducive to angiogenesis.FSTL1 bound to the receptor,DIP2A,to regulate angiogenesis mainly through the Smad2/3 signaling pathway.FSTL1-DIP2A directly activated Smad2/3 and was not affected by TGFbR1.Conclusion:Dynamic resistance exercise stimulates the expression of skeletal muscle-derived FSTL1,which could supplement the insufficiency of cardiac FSTL1 and promote cardiac rehabilitation through the DIP2A-Smad2/3 signaling pathway in MI rats.

The host type I interferon response to viral and bacterial infections

Type I interferons (IFN) are well studied cytokines with anti-viral and immune-modulating functions. Type I IFNsare produced following viral infections, but until recently, the mechanisms of viral recognition leading to IFN productionwere largely unknown. Toll like receptors (TLRs) have emerged as key transducers of type I IFN during viral infectionsby recognizing various viral components. Furthermore, much progress has been made in defining the signaling path-ways downstream of TLRs for type I IFN production. TLR7 and TLR9 have become apparent as universally importantin inducing type I IFN during infection with most viruses, particularly by plasmacytoid dendritic cells. New intracellularviral pattern recognition receptors leading to type I IFN production have been identified. Many bacteria can also inducethe up-regulation of these cytokines. Interestingly, recent studies have found a detrimental effect on host cells if type IIFN is produced during infection with the intracellular gram-positive bacterial pathogen, Listeria monocytogenes. Thisreview will discuss the recent advances made in defining the signaling pathways leading to type I IFN production.

Molecular Mechanisms Regulating Rapid Stress Signaling Networks in Arabidopsis

As sessile organisms plants must ronmental conditions. To survive cope with ever changing enviplants have evolved elaborate mechanisms to perceive and rapidly respond to a diverse range of abiotic and biotic stresses. Central to this response is the ability to modulate gene expression at both the transcriptional and posttranscriptional levels. This review will focus on recent progress that has been made towards understanding the rapid reprogramming of the transcriptome that occurs in response to stress as well as emerging mechanisms underpinning the reprogramming of gene expression in response to stress,

Ionic Mechanisms for the Acute Nociceptive Signals Induced by Bradykinin

Bradykinin is an inflammatory mediator and one of the most potent endogenous pain-inducing substances. When released at the site of tissue damage or inflammation

Investigation of Mechanism of Premature Ovarian Failure Regulation by Kidney-tonifying Herbs and Liver-clearing Herbs in Dingjing Decoction

Objective To investigate the mechanisms through which kidney-tonifying herbs（KTHs） and liver-clearing herbs（LCHs） in Dingjing Decoction（DJD） regulate premature ovarian failure（POF）. Methods One hundred and fifty Sprague-Dawley rats were randomly divided into five groups such as control, model, KTHs, LCHs, and DJD groups. POF-related biological molecules were examined. Factor analysis was performed to investigate the regulatory networks and key biomolecules involved in mediating POF after treatment with KTHs and LCHs. Results The master regulatory factors in the reproductive endocrine network associated with KTHs intervention included four molecules in the pituitary-ovarian axis, cortisol（CORT） in the target gland of pituitary-adrenal axis, and some molecules in the hypothalamus. In contrast, the master regulatory factors associated with LCHs intervention included four molecules in the pituitary-ovarian axis and some molecules in the hypothalamus; No biomolecules in the pituitary-adrenal axis were involved in the LCH-mediated mechanisms.Gonadotropin-releasing hormone（Gn RH）, which was identified as a common biological molecule in the hypothalamus, was involved in regulating the reproductive endocrine network in association with KTHs intervention. Conclusion KTHs directly regulates biological molecules in the pituitary-adrenal axis and indirectly regulates those in the pituitary-adrenal axis through the hypothalamus, while the LCHs only exert its effects indirectly. Gn RH is the key biological molecule associated with KTHs intervention.

A review of microfluidic approaches for investigating cancer extravasation during metastasis

Metastases,or migration of cancers,are common and severe cancer complications.Although the 5-year survival rates of primary tumors have greatly improved,those of metastasis remain below 30%,highlighting the importance of investigating specific mechanisms and therapeutic approaches for metastasis.Microfluidic devices have emerged as a powerful platform for drug target identification and drug response screening and allow incorporation of complex interactions in the metastatic microenvironment as well as manipulation of individual factors.In this work,we review microfluidic devices that have been developed to study cancer cell migration and extravasation in response to mechanical(section‘Microfluidic investigation of mechanical factors in cancer cell migration’),biochemical(section‘Microfluidic investigation of biochemical signals in cancer cell invasion’),and cellular(section‘Microfluidic metastasis-on-a-chip models for investigation of cancer extravasation’)signals.We highlight the device characteristics,discuss the discoveries enabled by these devices,and offer perspectives on future directions for microfluidic investigations of cancer metastasis,with the ultimate aim of identifying the essential factors for a‘metastasis-on-a-chip’platform to pursue more efficacious treatment approaches for cancer metastasis.

A crosstalk between auxin and brassinosteroid regulates leaf shape by modulating growth anisotropy

Leaf shape is highly variable within and among plant species,ranging from slender to oval shaped.This is largely determined by the proximodistal axis of growth.However,little is known about how proximal–distal growth is controlled to determine leaf shape.Here,we show that Arabidopsis leaf and sepal proximodistal growth is tuned by two phytohormones.Two class A AUXIN RESPONSE FACTORs(ARFs),ARF6 and ARF8,activate the transcription of DWARF4,which encodes a key brassinosteroid(BR)biosynthetic enzyme.At the cellular level,the phytohormones promote more directional cell expansion along the proximodistal axis,as well as final cell sizes.BRs promote the demethyl-esterification of cell wall pectins,leading to isotropic in-plane cell wall loosening.Notably,numerical simulation showed that isotropic cell wall loosening could lead to directional cell and organ growth along the proximodistal axis.Taken together,we show that auxin acts through biosynthesis of BRs to determine cell wall mechanics and directional cell growth to generate leaves of variable roundness.