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Mucin rare cores 5, 7, and 8 with 1,2-cis glycosidic bonds were prepared with exclusive stereo-selectivity from a versatile precursor. Enzyme-catalyzed regio-selective sialylation was then achieved, yielding natural sialylated rare cores.

Multipass amplifier systems in areas such as high-energy-density physics and astrophysics play an important role, but the undetermined stray light caused by defects seriously influencing the output signal-to-noise ratio (SNR) and even resulting in the failure of the main pulse bombardment. In this study, the modulation of nondeterministic stray light caused by the defects in the optical paths of different components in a multipass amplifier system was examined, and a Mie scattering model of multi-crack defects established. Using ray-tracing simulation, the spatial and temporal distribution of stray light was analysed, and experimental verification was conducted. The law of energy amplification for nondeterministic stray light caused by component defect modulation and an empirical formula for the signal to noise ratio of the pre-pulse system were established. This study provides a reference for the accurate troubleshooting of components, optical path defects and an important theoretical basis for the processing and correction of system components.

This study proposes a method to improve the production efficiency and photocatalytic performance of TiO2 nanoparticles using the pulsed laser ablation in liquid (PLAL) method to optimise preparation parameters. In this study, the variation of particle size, morphology, preparation, and catalytic efficiency due to the increase in the number of pulses is studied. The mechanism of particle morphology change is analysed using thermodynamic simulation. The density functional theory (DFT) is used to calculate and characterise the reason why the special structure formed by particle breaking improves the photocatalytic performance. In addition, the influence of the law of solution height on particle breakage is summarised to obtain an optimised preparation parameter. The proposed method provides a reference for the selection of parameters in actual production.

A new strategy was established for the degradation of wastewater-based organic pollutants. Laser-induced plasma (LIP) was used as an alternative UV light source to realise rapid photodegradation of methylene blue (MB), an organic pollutant. A conventional 1064 nm Nd:YAG laser was used for plasma excitation to degrade MB solutions. The results show that the LIP effectively degraded the organic matter, and the degradation efficiency was related to the UV component with wavelength less than 400 nm. The compositions of the plasma excited by different dielectric substrates are different owing to various mechanisms involving moderate heat dissipation and sonoluminescence. However, metallic substrates, especially Fe, can enhance the proportion of UV light and accelerate the degradation efficiency. In the process of methylene blue degradation, solution parameters, such as initial dye concentration, pH, irradiation time and hydrogen peroxide concentration, will affect the degradation efficiency. The conditions of effective degradation of methylene blue (10 mg L

Radiation therapy (RT) concurrent with chemotherapy improves local lung cancer control but may cause systemic toxicity. There is an unmet clinical need of treatments that can selectively sensitize cancer cells to RT. Herein, we explored a radiosensitizing strategy that combines doxorubicin (DOX)-encapsulated polyaspartamide nanoparticles and 5-aminolevulinic acid (5-ALA). The DOX-polyaspartamide nanoparticles were coupled with NTS

Background Cervical cancer (CC) is the second leading cause of cancer death among women worldwide. Epigenetic regulation of gene expression through DNA methylation and hydroxymethylation plays a pivotal role during tumorigenesis. In this study, to analyze the epigenomic landscape and identify potential biomarkers for CCs, we selected a series of samples from normal to cervical intra‐epithelial neoplasia (CINs) to CCs and performed an integrative analysis of whole‐genome bisulfite sequencing (WGBS‐seq), oxidative WGBS, RNA‐seq, and external histone modifications profiling data. Results In the development and progression of CC, there were genome‐wide hypo‐methylation and hypo‐hydroxymethylation, accompanied by local hyper‐methylation and hyper‐hydroxymethylation. Hydroxymethylation prefers to distribute in the CpG islands and CpG shores, as displayed a trend of gradual decline from health to CIN2, while a trend of increase from CIN3 to CC. The differentially methylated and hydroxymethylated region‐associated genes both enriched in Hippo and other cancer‐related signaling pathways that drive cervical carcinogenesis. Furthermore, we identified eight novel differentially methylated/hydroxymethylated‐associated genes (DES, MAL, MTIF2, PIP5K1A, RPS6KA6, ANGEL2, MPP, and PAPSS2) significantly correlated with the overall survival of CC. In addition, no any correlation was observed between methylation or hydroxymethylation levels and somatic copy number variations in CINs and CCs. Conclusion Our current study systematically delineates the map of methylome and hydroxymethylome from CINs to CC, and some differentially methylated/hydroxymethylated‐associated genes can be used as the potential epigenetic biomarkers in CC prognosis., The differentially DMR/DhMR occurred earlier and much more than that of CNVs which would be more suitable for a marker to detect the disease progression.The differentially DMR/DhMR‐associated genes enrich in Hippo and other cancer‐related signaling pathways.Eight DMR/DhMR‐associated genes significantly correlate with the overall survival of CC.

This study proposes a method to improve the production efficiency and photocatalytic performance of TiO2 nanoparticles using the pulsed laser ablation in liquid (PLAL) method to optimise preparation parameters. In this study, the variation of particle size, morphology, preparation, and catalytic efficiency due to the increase in the number of pulses is studied. The mechanism of particle morphology change is analysed using thermodynamic simulation. The density functional theory (DFT) is used to calculate and characterise the reason why the special structure formed by particle breaking improves the photocatalytic performance. In addition, the influence of the law of solution height on particle breakage is summarised to obtain an optimised preparation parameter. The proposed method provides a reference for the selection of parameters in actual production.

We use laser-induced plasma shock waves to remove Al nanoparticles from a smooth silicon substrate. Our experimental results show that the removal mechanism varies for different substrate regions. We examine the factors influencing particle removal by evaluating the shock-wave spatial distribution and the removal mechanisms. Further, we evaluate the influence of the gap between the laser focus and substrate on the removal results. The effects of the laser focus and substrate particle sizes are also investigated, and the optimum removal conditions are obtained. Our study can aid in better understanding the mechanisms of particle removal from surfaces.

Research on tourism has gradually focused on the study of well-being, but relatively little attention has been paid to the psychological well-being of tourism practitioners. This study adopted the theoretical lens of explanatory style and the PERMA model (P = positive emotion, E = engagement, R = relationships, M = meaning, A = accomplishment) to investigate the influence of tourism practitioners’ explanatory style on their psychological well-being (PWB). The survey study demonstrated that explanatory style was significantly related to PWB; whilst an optimistic explanatory style was positively related to PWB, a pessimistic explanatory style was negatively related to it. Additionally, in the context of Chinese culture, tourism practitioners were inclined to attribute PWB to internal, stable, and specific causes. This study falls within the extensive field of occupational health psychology and theoretically contributes to the literature by connecting positive psychology and its effects on practitioners in the tourism context. Meanwhile, there are similarities and differences between the PWB and explanatory style in the Chinese cultural context and in the Western context. This finding has practical implications for generalizing the PWB of tourism practitioners in different cultural backgrounds, especially in countries with Eastern cultural backgrounds, further improving the sustainable development of tourism destinations.

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N6-methyladenosine (m6A) represents the most abundantly occurring mRNA modification and is involved in the regulation of skeletal muscle development. However, the status and function of m6A methylation in prenatal myogenesis remains unclear. In this study, we first demonstrated that knockdown of METTL14, an m6A methyltransferase, inhibited the differentiation and promoted the proliferation of C2C12 myoblast cells. Then, using a refined m6A-specific methylated RNA immunoprecipitation [RIP] with nextgeneration sequencing (MeRIP-seq) method that is optimal for use with samples containing small amounts of RNA, we performed transcriptome-wide m6A profiling for six prenatal skeletal muscle developmental stages spanning two important waves of porcine myogenesis. The results revealed that, along with a continuous decrease in the mRNA expression of the m6A reader protein insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1), the m6A methylome underwent highly dynamic changes across different development stages, with most of the affected genes being enriched in pathways related to skeletal muscle development. RNA immunoprecipitation confirmed that IGF2BP1 targets 76 genes involved in pathways associated with muscle development, including the key marker genes MYH2 and MyoG. Moreover, small interfering RNA (siRNA)-mediated knockdown of IGF2BP1 induced phenotypic changes in C2C12 myoblasts similar to those observed with knockdown of METTL14. In conclusion, we clarified the dynamics of m6A methylation and identified key genes involved in the regulatory network of porcine skeletal muscle development.

BackgroundN6-methyladenosine (m6A) is the most abundant RNA modification and essentially participates in the regulation of skeletal muscle development. However, the status and function of m6A methylation in prenatal myogenesis remains unclear now.ResultsIn our present study, we first demonstrate that chemical suppression of m6A and knockdown METTL14 significantly inhibit the differentiation and promote the proliferation of C2C12 myoblast cells. The mRNA expression of m6A reader protein IGF2BP1, which functions to promote the stability of target mRNA, continually decreases during the prenatal skeletal muscle development. Thereafter, profiling transcriptome-wide m6A for six developmental stage of prenatal skeletal muscle, which spanning two important waves of pig myogenesis, were performed using a refined MeRIP sequencing technology that is optimal for small-amount of RNA samples. Highly dynamic m6A methylomes across different development stages were then revealed, with majority of the affected genes enriched in pathways of skeletal muscle development. In association with the transcriptome-wide alterations, transcriptional regulatory factors (MyoD) and differentiated markers (MyHC, MYH1) of muscle development are simultaneously regulated with m6A and IGF2BP1. Knockdown of IGF2BP1 also suppresses myotube formation and promotes cell proliferation.ConclusionsThe present study clarifies the dynamics of RNA m6A methylation in the regulation of prenatal skeletal muscle development, providing a data baseline for future developmental as well as biomedical studies of m6A functions in muscle development and disease.

Paint removal by laser ablation is favoured among cleaning techniques due to its high efficiency. How to predict the optimal laser parameters without producing damage to substrate still remains challenging for accurate paint stripping. On the basis of ablation morphologies and combining experiments with numerical modelling, the underlying mechanisms and the optimal conditions for paint removal by laser ablation are thoroughly investigated. Our studies suggest that laser paint removal is dominated by the laser vaporization effect, thermal stress effect and laser plasma effect, in which thermal stress effect is the most favoured while laser plasma effect should be avoided during removal operations. Based on the thermodynamic equations, we numerically evaluated the spatial distribution of the temperature as well as thermal stress in the paint and substrate under the irradiation of laser pulse at 1064 nm. The obtained curves of the paint thickness vs. threshold fluences can provide the reference stand...

As a key optical material in high-energy laser system, the laser induced damage of fused silica glass has been one of the bottlenecks to limit output of the laser influence. In this paper, the morphology of fractures on fused silica glass surface as well as phase transition caused by laser pulse shock wave have been investigated in theory and experiment, and we found that the whole fracture region can be divided into hackle zone, mist zone and mirror zone, which were produced by the tip of hoop stress formed in glass under the action of laser plasma shock wave. During cracks initiating and propagating of fused silica glass, the existing of cracks can reduce the relative content of three- and four-number rings structures corresponding to the stishovite and the coesite which caused by the absence oxygen free, this kind of change may destroy the mesh topology severely, and induce phase transitions. From the micro level, the non-bridging oxygen hole center and E' center lead to the decrease of the optical band gaps as well as transmittance which seriously affect the performance of glass.

This study was conducted to purify and identify metabolites of antimicrobial activity against phytopathogens from Xenorhabdus nematophila YL001. Three dipeptide compounds were purified from its cell-free cultural broth and identified as (±)-nematophin, cyclo (L-Pro-Gly), and N, N′-dimethyl-cyclo (L-Phe-L-Leu). Nematophin demonstrated a wider antifungal spectrum than the other two compounds. It also exhibited strong inhibitory effects on mycelial growth of Rhizoctonia solani and Phytophthora infestans with EC50 values of 40.00 and 51.25 μg/ml, respectively. Its (S)-configuration structure [(+)-nematophin] was also synthesized and exhibited higher antimicrobial activity than the enantiomeric mixture. The detached leaf assay revealed that nematophin possessed significant preventive and curative efficacy against R. solani on broad bean leaves showing corresponding control efficacies of 93.01 and 94.93% at 1,000 μg/ml, comparable to those of a chemical fungicide (carbendazim) at 500 μg/ml. Additionally, the pot experiments indicated that nematophin could effectively inhibit the disease extension on rice and broad bean plants caused by R. solani. Nematophin also exerted some adverse influences on the sclerotial development of R. solani by dramatically suppressing their formation and maturation at 40.00 μg/ml, as well as their germination at 15.00 μg/ml. Morphological and ultrastructural observations showed that the hyphae of R. solani became twisted, shriveled, and deformed at the growing points after exposure to nematophin at 40.00 μg/ml, and that the subcellular fractions also became abnormal concurrently, especially the mitochondrial structure. These results indicate that nematophin has great potential to be used as a bio-pesticide in agricultural production.

With technological advancement, plasma shockwaves have become widely used as a novel cleaning method to remove nanoparticles. However, insufficient research has been conducted on their cleaning mechanism and application conditions, and the yield strength of substrates has been directly used as their damage threshold. we find that this definition is inaccurate. We treat clean and nanoparticle-coated silicon substrates with a laser-induced plasma shockwave to explore the effects of the presence of nanoparticles on the substrate during cleaning. We have confirmed the effect of nanoparticles on the substrate by simulating the mechanism of temperature and stress propagation between the particles and the substrate. This is because the yield strength of the substrate is greatly reduced by the increase of temperature under the action of shock wave. At the same time, the stress transferred by particles to the substrate increases, resulting in local high-pressure area and pit formation. Moreover, this study finds that the presence of nanoparticles increases the probability of damage to the substrate by an approximate factor of two. And the dependence of the damage threshold of the substrate on the size of the nanoparticles is demonstrated.

Micro/nanoparticles contamination is one of the key factors affecting the quality of precision manufacturing, and the traditional cleaning methods cannot function effectively. The laser plasma has high temperature and pressure, which can be used as a new and potential method to implement the removal of micro/nanoparticle, and it has become the focus of attention. This paper aims to analyze the particles removal process under the action of repetitively pulsed laser plasma, which is mainly composed of the changes in particle morphologies, the ultimate removal results, as well as the corresponding academic analysis based on the thermodynamic effects. Investigation results show that the particles removal characteristics depend heavily on the number of pulsed plasma, micrometer-size particles can be removed at the beginning, and then particles with the size about several hundred nanometers in the following stages. Analyzed from the morphological properties of particles, the refinement can be found, more specifically, the particle can be broken up into more smaller ones under the action of laser plasma with high pressure and temperature. The particles refinement will deepen the difficulty on removal efficiency, and when the particles ultimately convert into ultrasmall nanoparticles with several nanometers, which will attach to substrate presenting as flocculent aggregate, and cannot be completely wiped out.

The technology of oil-water separation is very important for the improvement of water resources and environment. The detection of oil-water interface characteristics is one of the key requirements of the technology. In this paper, the laser plasma spectroscopy is used to detect the oil-water interface, and the theoretical research and verification are carried out. The spatial distribution characteristics of plasma electron temperature and electron density are experimentally studied. The semi-ellipsoid model of laser plasma spatial distribution is proposed, combined with the laser focusing characteristic. The position of oil-water interface was determined by the laser-induced plasma spectroscopy based on the difference of element luminescent characteristics. According to the relationship between the intensity of spectral lines and the concentration of elements, the relationship between the intensity of characteristic spectral lines and the number of elements is obtained based on the semi-ellipsoid model. Furthermore, the relationship between the intensity ratio of characteristic elements and the thickness of the oil film is studied, and the spectral measurement of oil layers with different thickness is realized. In this paper, the law of the self-absorption effect of C and H elements with the thickness of the oil film is analyzed, and the rationality of the direct judgment of oil film thickness by the relative strength ratio of the characteristic elements of the detection spectrum signal is verified. According to the intensity ratio of spectral lines, the scatter distribution of oil thickness, and the simulation curve, the variation rule of experimental error with oil thickness are obtained. The relative error is less than 20%, which also verifies the reliability of the method.

Micro-impurity pollution is always one of the key factors affecting the quality and service life of precision devices. Micro-nano impurity particles are difficult to remove by traditional cleaning methods (ultrasonic cleaning, etc.) and low removal efficiency by laser cleaning methods (dry laser cleaning, etc.). The laser plasma shock wave has high pressure and high temperature characteristics, which can remove nano-scaled impurity particles, and has great potential applications. In this work, we mainly study the thermodynamic effect of the laser plasma in the process of removing micro- and nano-particles. In this work, the Al particles on the Si substrate are removed by laser plasma shock wave, and the transformation of the particle state is discussed through the changes of the experimental sample morphology after different pulse effects. The experimental results show as follows With the increase of the pulse number, the micro- and nano-particle residues gradually decrease. At the same time, on the surface of the sample after these particles are removed, it can be found that large particles break up into small particles, and some of the particles will change into smooth spheres when their temperatures reach the melting point. These phenomena are the result of the interaction of the thermodynamic effect of the plasma. In order to study the transformation process of particle state, based on the plasma shock wave propagation theory, the evolution law of pressure characteristic and temperature characteristic of shock wave are obtained. From the evolution law, it can be seen that with the increase of shock wave radius, the pressure and temperature gradually decrease. When the shock wave propagates to the surface of a sample, it can reach the compression threshold and correspondingly the surface temperature arrives at melting temperature of particles, which are consistent with the experimental results. By using the finite element simulation method, the pressure and temperature of laser plasma shock wave acting on particles are studied. The stress distribution and temperature distribution in particles varying with time are obtained. The analysis results are consistent with the experimental results, and therefore the thermodynamic mechanism of plasma on particles is obtained.

Ta2O5 thin film has many advantages: wide spectral range, high refractive index and so forth, which endow Ta2O5 with great potentials in high power laser systems. Based on experimental observations and thermodynamic process analysis, the Ta2O5 thin film damage by Gaussian beam of nanosecond pulses was investigated. For the Gaussian beam, laser pulse energy is concentrated at the center of the laser beam, which determines the ablation characters. The material removal is deepest at the center and gradually decreases along radial direction, rendering the removal profile funnel-shaped. The ablation microstructures are characterized by resultant nano-particles owing to ablation in the concave–convex structures. The nano-particles spread gradually from the center throughout the ablation region. This variation is mainly due to the transition of the film damage from melting into atomization and ultra-high temperature melting and cooling.

The damage problem of fused silica has always been one of the bottlenecks limiting the energy output of the high-power laser system. For optical components, the ionization breakdown by laser is the main factor causing damage, especially for laser plasma shock wave, which can cause large-scale fracture damage in fused silica. In this paper, the fused silica damage experiment was induced by nanosecond laser, and the damage morphology of fused silica in the thickness range of 0.8-5.0 mm was obtained under the action of 1-20 pulse. The damage size of fused silica decreases as the thickness of the material increases until the thickness of the material is greater than or equal to 1.4 mm. On the basis of theoretical analysis of plasma shock wave, the coupling and transmission of shock wave in fused silica were studied by finite element method, and the magnitude and direction distribution of stress were obtained. By analyzing the fracture characteristics and Raman spectra of the three damaged regions of fused silica, the structural differences of different damage regions are analyzed, and the relationship between the macroscopic damage of fused silica and the microstructure is explained. The research results can give a reference for understanding the characteristics and mechanism of damage characteristics induced by laser plasma shock wave.

The damage to the rear surface of fused silica under the action of high power laser is more severe than that incurred by the front surface, which hinders the improvement in the energy of the high power laser device. For optical components, the ionization breakdown by laser is a main factor causing damage, particularly with laser plasma shock waves, which can cause large-scale fracture damage in fused silica. In this study, the damage morphology is experimentally investigated, and the characteristics of the damage point are obtained. In the theoretical study, the coupling and transmission of the shock wave in glass are investigated based on the finite element method. Thus, both the magnitude and the orientation of stress are obtained. The damage mechanism of the glass can be explained based on the fracture characteristics of glass under different stresses and also on the variation of the damage zone’s Raman spectrum. In addition, the influence of the glass thickness on the damage morphology is investigated. The results obtained in this study can be used as a reference in understanding the characteristics and mechanism of damage characteristics induced by laser plasma shock waves.

As a material that exhibits a high refractive index and an excellent chemical stability, Ta2O5 is widely used in the microelectronics and chemical industries. In this study, we analyzed the effect of plasma shock waves on Ta2O5 thin films. The experimental results showed that the damage characteristics of the film include thermal ablation, surface cracks, and peeling off from the substrate owing to the repeated action of the pulse. Coating characterization before and after exposure to laser plasma was performed using UV-Vis spectroscopy, energy dispersive spectroscopy (EDS), Raman spectroscopy, and X-ray diffraction. With the increase in the light absorbed by the ablated products, the transmittance of the film decreased after damage, and the Raman spectrum and X-ray diffraction pattern of the sample indicated that the film changes from an amorphous to a crystalline structure owing to the action of the high-temperature and high-pressure plasma. The EDS analysis results indicated that the oxygen content in the film decreases because of the damage inflicted to its structure.

The femtosecond laser-induced phase modulation based on KTP crystal is demonstrated. The phase modulation in femtosecond laser irradiated area is deduced through Drude model and color centers model, and the phase shift was also measured by cyclic radial shearing interferometer. As a result, a phase modulator with 2π phase shift is achieved using a 2.5-mm-thick KTP crystal and femtosecond laser pulses, and the spatial distribution of phase shift was also given. Such approach will be of great potential values for optical cross-connect switching, laser beam steering, low-cost electro-optic sensor, adaptive optics, coherent beam combination.

Since the processes of normal embryogenesis and neoplasia share many of similar pathways, tumor development has been interpreted as an abnormal form of organogenesis. NANOG is a homeodomain-containing transcription factor that functions to maintain self-renewal and proliferation of embryonic stem cells (ESCs). Aberrant expression of NANOG has been observed in many types of human malignancies. However, its potential implication in tumorigenesis has not been fully clarified. In this study, we have employed small interference RNA (RNAi) technology to silence endogenous NANOG expression in breast cancer cells and successfully selected three independent clones with stably inhibited NANOG expression of MCF-7 cells. Functional analysis revealed that down-regulation of NANOG reduced cell proliferation, colony formation and migration ability of MCF-7 cells. Consistently, proliferation of breast cancer MDA-MB-231 cells was also significantly inhibited after the knockdown of NANOG expression. Interestingly, we found that the expression levels of cyclinD1 and c-myc were markedly down-regulated and the cell cycle were blocked at the G0/G1 phases after the knockdown of NANOG, while the expression of cyclinE and signal transducers and activators of transcription3 (STAT3) remained unaffected. In addition, the expression of NANOG and cyclinD1 can be rescued after the transfection of pcDNA3.1 (-)-NANOG expression vector into the three clones. Finally, our chromatin immunoprecipitation (ChIP) experiment showed that NANOG protein can bind to the promoter region of cyclinD1 and regulate cells cycle. Taken together, our findings may not only establish a molecular basis for the role of NANOG in modulating cell cycle progression of breast cancer cells but also suggest a potential target for the treatment of at least some subtypes of breast cancer.

A functional drug carrier comprised of folic acid modified lipid-shell and polymer-core nanoparticles (FLPNPs) including poly(D,L-lactide-co-glycolide) (PLGA) core, PEGylated octadecyl-quaternized lysine modified chitosan (PEG-OQLCS) as lipid-shell, folic acid as targeting ligand and cholesterol was prepared and evaluated for targeted delivery of paclitaxel (PTX). Confocal microscopy analysis confirmed the coating of the lipid-shell on the polymer-core. Physicochemical characterizations of FLPNPs, such as particle size, zeta potential, morphology, encapsulation efficiency, and in vitro PTX release, were also evaluated. The internalization efficiency and targeting ability of FLPNPs were demonstrated by flow cytometry and confocal microscopy. PTX loaded FLPNPs showed a significantly higher cytotoxicity than the commercial PTX formulation (Taxol®). The intravenous administration of PTX encapsulated FLPNPs led to tumor regression and improvement of animal survival in a murine model, compared with that observed with Taxol® and biodistribution study showed that PTX concentration in tumor for PTX encapsulated FLPNPs was higher than other PTX formulations. Our data indicate that PTX loaded FLPNPs are a promising nano-sized drug formulation for cancer therapy.

Based on the statistics of 1993-2010, this paper analyzes the changing trend and causes of terms of trade in China and studies the overall movement in China’s national wealth by introducing the GDI index under SNA accounting framework. This paper analyzes the relevance between export and real GDP by using the Pearson correlation and partial correlation method, with the final consumption as the economic welfare evaluation index. This paper also presents the change of national wealth by using the weak axiom of revealed preference theory. The result of the study shows that, China’s economic growth is not strongly dependent on exports. It is the export structure of labor intensive products with low price elasticity that mainly lead to the continuously decline of terms of trade in China. However the loss of welfare from the terms of trade’s decline is not enough to offset the benefits of the economic growth. Therefore there is no probability of “Immiserizing Growth” in China’s foreign trade.

The evolution of gray-tracking damage due to high repetition rate laser pulses was experimentally studied. “Dark track” owing to Ti 3+ + O 2− centers induced by multi-photon absorption was found on the damaged KTP crystal. Moreover, the accumulative process of gray-tracking was simulated through iterating the equation of the number of color centers produced during an arbitrary laser pulse and the method for decreasing gray-tracking based on the simulated results is proposed. The color center model in combination with broken bonds model successfully explains the catastrophic damage, and the hole-like damage pattern can be interpreted by the pressure distribution of laser-supported detonation wave (LSDW).

The experimental results show that if the pulse energy is low, the damage does not occur and the corresponding transmissivity is 100%. But with the increase of the pulse energy, the damage occurs and the transmissivity decreases to between 100% and 50%, equal to 50% and lower than 50%.The concept of the cut-off time (Tcut) is proposed to give the physics explanation on it, and by taking the free electron density (FED) and the laser-induced damage threshold (LIDT), mathematical simulation of the change law of the Tcut and the corresponding energy transmissivity with the laser energy has been done, respectively. The analysis results indicate that the former definition method can predict all the situations successfully, but the second one cannot predict the situation of the transmissivity being between 100% and 50%, the reasons of this difference also be analyzed.

The characteristics and mechanisms of the damage to absorbing glass with high-repetition laser pulses (several kHz) are discussed. The results show that: (1) in the range of comparatively low-repetition rate, the damage is characterized by material melting and a small crater on the surface of substrate; (2) with the increase in repetition rate, a bigger and deeper crater is surrounded by re-deposition and crystalline granules originating from the cooling of vapor; and (3) the crater, surrounded by evaporation and an large number of solid particulates which is obviously the characters of phase explosion, becomes even bigger and deeper when the repetition rate is further increased. We modeled the temperature distribution in different repetition rate regime and found that heat accumulation plays a significant role in damage process. Because of the temperature dependence of damage mechanism, the temperature of the area irradiated by laser beam will ramp up with increasing the repetition rate, which triggers the melting and evaporation of dielectrics and phase explosion successively. Our results may benefit the understanding of laser-induced damage in optical materials.

SummaryHow autophagy, an evolutionarily conserved intracellular catabolic system for bulk degradation, selectively degrades protein aggregates is poorly understood. Here, we show that several maternally derived germ P granule components are selectively eliminated by autophagy in somatic cells during C. elegans embryogenesis. The activity of sepa-1 is required for the degradation of these P granule components and for their accumulation into aggregates, termed PGL granules, in autophagy mutants. SEPA-1 forms protein aggregates and is also a preferential target of autophagy. SEPA-1 directly binds to the P granule component PGL-3 and also to the autophagy protein LGG-1/Atg8. SEPA-1 aggregates consistently colocalize with PGL granules and with LGG-1 puncta. Thus, SEPA-1 functions as a bridging molecule in mediating the specific recognition and degradation of P granule components by autophagy. Our study reveals a mechanism for preferential degradation of protein aggregates by autophagy and emphasizes the physiological significance of selective autophagy during animal development.

For the purpose of quantitatively evaluating laser-induced damage in optical glass, image processing was employed. The image processing involves an improved watershed segmentation algorithm, with the aid of which different morphologies of laser damage in glass were classified. The shapes and distribution of cracks can be readily discerned in the gradient image while the severity of damage is apparent in the gray-scale image after being filtered; in addition, the marker image can be utilized to recognize the region where the damage appears; the final segmentation embodies all characteristics of damaged area and is an effective means of analyzing the laser damage in optical glass.

Directed assembly of metal oxide nanoparticles with the aid of DNA was investigated. One-dimensional arrangement of zirconia (ZrO 2 ) nanoparticles using DNA as a template was shown by TEM observation. It is considered that the DNA-directed assembly of ZrO 2 nanoparticles is due to the Coulomb interactions between the negatively charged DNA and positively charged ZrO 2 nanoparticles.