时尚搭配——移动装备用音箱导购

现在越来越多的年轻人在户外运动、野营、旅行、郊游等活动时,都需要有音乐陪伴。他们喜欢把手机、平板电脑等移动装备随身携带,满足随时聆听音乐的需求。不过有时戴上耳机并不适合＂聚会＂场合,独乐乐不如众乐乐,把音乐放出来给大家欣赏,一来活跃气氛,同时又可增加朋友之间的感情,为了在户外外放音乐,便携音响就成了出行必备听音设备。

Growth Control of Quasi-two-dimensional Perovskites:Structure-dependent Exciton and Charge Behavior

While three-dimensional perovskites have high defect tolerance and an adjustable bandgap,their charges tend to be free rather than forming excitons,making them unsuitable for use in efficient light-emitting diodes(LEDs).Rather,quasi-two-dimensional(Q-2D)perovskites offer high photoluminescence quantum yield along with the advantages of bulk perovskites,making them ideal for high-performance LEDs.In Q-2D perovskites,the structure(which includes factors like crystal orientation,phase distribution,and layer thickness)directly influences how excitons and charge carriers behave within the material.Growth control techniques,such as varying the synthesis conditions or employing methods,allow for fine-tuning the structural characteristics of these materials,which in turn affect exciton dynamics and charge transport.This review starts with a description of the basic properties of Q-2D perovskites,examines crystal growth in solution,explains how structure affects energy transfer behavior,and concludes with future directions for Q-2D perovskite LEDs.By understanding and optimizing the structure-dependent behavior,researchers can better control exciton dynamics and charge transport,which are crucial for enhancing the performance of optoelectronic devices like solar cells and LEDs.

Topographic effects on long offset transient electromagnetic response

The forward modeling procedure used in this article is formulated with the volume integral equation based on the tensor Green＇s function. The electromagnetic components responses are first calculated in the frequency domain and then transformed to the time domain by digital filtering. The valley and hill topography with a layered earth is stimulated by a horizontal electric dipole （HED） transmitter, which is common in field surveys, and the TEM responses are calculated at the transmitter and receivers. The topography effects on the long offset electromagnetic transient （LOTEM） responses are discussed in detail. The results show that both valley and hill topography has significant effect on the LOTEM measurement. If the HED is located in the bottom of a valley, the distortion of the observed anomalous field at distance is severe. A valley at the receiver locations show a strong effect but are localized in space and time. In general, hill-shaped topography shows smaller effects no matter where its located. When the topography is located between source and receivers, the influence is negligible. We conclude that the location of the source is much more important than the receivers and it is critical to put the transmitter in an open flat area in the field survey.

Cooperative navigation and localization for multiple UUVs

The authors proposed a moving long baseline algorithm based on the extended Kalman filter （EKF） for cooperative navigation and localization of multi-unmanned underwater vehicles （UUVs）. Research on cooperative navigation and localization for multi-UUVs is important to solve navigation problems that restrict long and deep excursions. The authors investigated improvements in navigation accuracy. In the moving long base line （MLBL） structure, the master UUV is equipped with a high precision navigation system as a node of the moving long baseline, and the slave UUV is equipped with a low precision navigation system. They are both equipped with acoustic devices to measure relative location. Using traditional triangulation methods to calculate the position of the slave UUV may cause a faulty solution. An EKF was designed to solve this, combining the proprioceptive and exteroceptive sensors. Research results proved that the navigational accuracy is improved significantly with the MLBL method based on EKF.

Quantum Well Intermixing of InGaAsP QWs by Impurity Free Vacancy Diffusion Using SiO_2 Encapsulation

Experiment on quantum well intermixing (QWI) of InGaAsP QWs by impurity free vacancy diffusion (IFVD) using SiO 2 encapsulation is reported.A maximum band gap wavelength blue shift as large as 200nm is realized.Furthermore,an FP laser blue shifted 21nm by QWI is fabricated with characteristics comparable with the as grown one.

Optimized nonhyperbolic moveout correction equation of long-offset seismic data for TI media with an arbitrary spatial orientation

The conventional long-offset nonhyperbolic moveout equation is derived for the transverse isotropic media with a vertical symmetric axis（VTI）.It cannot be extended to the transverse isotropic media with an arbitrary spatial orientation of symmetry axis（ATI）.In this paper,we optimize a modified long-offset nonhyperbolic moveout equation for ATI media based on the conventional nonhyperbolic moveout equation and the exact analytical solution of the quartic moveout coefficient（A_4） and NMO velocity for ATI media that were derived in our previous work.Compared with the exact traveltimes of the ray-tracing algorithm for anisotropic media,this optimized equation can be used to calculate the traveltime varying with survey line azimuth in arbitrary strong or weak ATI media.It can replace the time-consuming, multi-offset,and multi-azimuth ray tracing method for forward modeling of long-offset reflection traveltimes in ATI media,which is useful to further anisotropic parameter inversion using long-offset nonhyperbolic moveout.

A Method of Measuring Large Displacement and Deformation with High Precision *

A CCD position detecting system measuring the displacement and deformation of structure is presented. The measure method takes advantage of the position detecting technique based on digital image processing. A bright spot is pegged on the object to be measured and imaged to the target of CCD camera through a telescopic lens. The CCD target converts the optical signal to equivalent electric signal. The video frequency signal is digitized to an array of 512×512 pixels by the analog to digital converter (ADC), then transmitted to the computer. The computer controls the data acquisition, conducts image processing and detects the location of the target spot. Comparing the current position with the original position of the spot, the displacement of object is obtained. With the aid of analysis software, the system can achieve the resolution of 0 01 mm in the 6 m distance from the object to the point of observation. To meet the need of practice, the measuring distance can be extended to 100 m or even farther.

档案,我要替你诉说……

也许是工作的缘份,也许是机遇的恩赐,我有幸结识了你这位默默无闻的知音。近十年的朝夕相处,使我深深地了解了你的品格,更体味到了你的奉献,我有责任、有义务替你诉说……凭心而论,在工厂这个大家族中,你不属于那种特别受人青睐的宠儿。有时候,你还真有一种倍受冷落的寂寞。可,你似乎已经习惯了自己的这种处境,也似乎习惯了自己的寂寞,你从来不经意人们对你的冷热。

Theoretical Analysis of a New Artificial Plastic Hinge at the Frame Beam End

Opening horizontal slit in the middle web of the beam end formed a new type of artificial plastic hinge. The calculation formulas about the hinge’s interior force and bearing capacity are set up. Based on these, the condition of transfer, the location of crack and the cracking length of the artificial plastic hinge were studied further. The calculation method for the ductility factor was also presented. The calculation results and the test ones were compatible.

太原市人民政府办公厅关于全面完成创建省级园林城市各项任务的紧急通知

各区人民政府: 经各级各部门共同努力,我市创建省级园林城市工作已取得很大进展,但尚有部分项目未完成或未全面完成。为了确保2004年创建省级园林城市目标的实现。

令人兴叹的迁居

随着季节的变化，动物们会进行方向确定、有规律、长距离的迁居活动。在动物界，类似的活动非常常见。鸟类一般都叫“迁徙”，鱼类称为“洄游”，哺乳动物则称为“迁移”。现在，我们分别请了这三类中的代表，说说它们的迁居经历。

cGH Gene Transfer and PCR Detection in Crucian Carp

By inserting the CMV with HSV TK promoter into the plasmid pBlue-cGH which contained cGH gene, a chimeric expression vector was constructed for transgenic fish. After the vector was transferred into fertilized eggs of crucian carp by means of microinjection, the transgenic crucian carp was obtained. The result of PCR detection showed that the growth hormone gene of the exogenous carp was integrated into the genome of crucian carp, and the transgenic crucian carp displayed enhancement of its growth.

Effects of epidermal growth factor on the growth of human gastric cancer cell and the implanted tumor of nude mice

AIM: Epidermal growth factor (EGF) plays an important role in the regulation of gastrointestinal tissue growth and development, and it can stimulate epithelial proliferation, cell differentiation and growth. It has been established that the EGF can promote gastric cytoprotection and ulcer healing. But the potential ability of EGF to regulate the gastric cancer growth is unknown. This study is to investigate the influence of EGF on human gastric cancer cell and the implanted tumor growth of nude mice. METHODS: The cell growth rates of human gastric adenocarcinoma cell lines MKN-28, MKN-45, SGC-7901 and normal human gastric epithelial cells 3T3 were assessed when incubated with recombinant human EGF (rhEGF, 0.05, 0.1, 0.5, 1.0, 10, 50, 100 mg.L(-1)) using MTT method. The cells of MKN-28, MKN-45, SGC-7901 (gastric cancer tissue 1.5mm(3)) were implanted in the BALB/cA nude mice for 10 days.The EGF was given intraperitoneally (15, 30, 60 microg.kg(-1)) for 3 weeks. The body weights of the tumor-bearing animals and their tumor mass were measured afterwards to assess the mitogenic effect of rhEGF in the nude mice. RESULTS: Within the concentration range of 0.05-100mg.L(-1), rhEGF could increase the cell growth of normal 3T3 cells (cell growth rate 100% vs 102.8%, P【0.05), but partially restrain the gastric cancer cell growth. The latter effect was related to cell differentiation. In 15-60 microg/kg rhEGF groups, the mean implanted tumor mass of MKN-28 cell were 1.75 g, 1.91 g, 2.08 g/NS group 1.97 g (P】0.05), the mean tumor mass of SGC-7901 cell were 1.53 g, 1.07 g, 1.20 g/NS group 1.07 g (P】0.05), and for MKN-45 cell, the tumor mass were respectively 1.92 g, 1.29 g, 1.77 /NS group 1.82 g (P】0.05). So rhEGF had no obvious effect on implanted MKN-28, SGC-7901 and MKN-45 tumor growth. CONCLUSION: EGF has no stimulating effect on the human gastric cancer cell growth neither in vitro nor in vivo.

mi R-382 functions as a tumor suppressor against esophageal squamous cell carcinoma

AIM To explore the effect of miR-382 on esophageal squamous cell carcinoma (ESCC) in vitro and its possible molecular mechanism. METHODS Eca 109 cells derived from human ESCC and Het-1A cells derived from human normal esophageal epithelium were used. Lentivirus-mediated miR-382 was overexpressed in Eca109 cells. The effect of miR-382 on cell proliferation was evaluated by MTT and colony formation assay. For cell cycle analysis, cells were fixed and stained for 30 min with propidium iodide (PI) staining buffer containing 10 mg/mL PI and 100 mg/mL RNase A, and analyzed by BD FACSCalibur (TM) flow cytometer. For cell apoptosis assay, cells were stained with an Annexin V-FITC/PI Apoptosis Detection Kit according to the manufacturer's instructions and analyzed by a dual-laser flow cytometer. Cell invasion and migration abilities were determined through use of transwell chambers, non-coated or pre-coated with matrigel. Levels of proteins related to cell growth and migration were examined by western blotting. RESULTS Endogenous miR-382 was down-regulated in Eca109 cells compared with Het-1A. Introduction of miR-382 not only significantly inhibited proliferation and colony formation, but also arrested cell cycle at the G2/M phase, as well as promoted apoptosis and autophagy in Eca109 cells. Migration, invasion and epithelial-mesenchymal transition of Eca109 cells were suppressed by overexpressing miR-382. Western blotting results showed that miR-382 inhibited the phosphorylation of mTOR and 4E-BP1. CONCLUSION miR-382 functions as a tumor suppressor against ESCC development and metastasis, and could be considered as a potential drug source for the treatment of ESCC patients.

Transforming growth factor-β and fibrosis

Transforming growth factor-β （TGF-β）, a prototype of multifunctional cytokine, is a key regulator of extracellular matrix （ECM） assembly and remodeling. Specifically, TGF-β isoforms have the ability to induce the expression of ECM proteins in mesenchymal cells, and to stimulate the production of protease inhibitors that prevent enzymatic breakdown of the ECM. Elevated TGF-β expression in affected organs, and subsequent deregulation of TGF-β functions, correlates with the abnormal connective tissue deposition observed during the onset of fibrotic diseases. During the last few years, tremendous progress has been made in the understanding of the molecular aspects of intracellular signaling downstream of the TGF-β receptors. In particular, Smad proteins, TGF-β receptor kinase substrates that translocate into the cell nucleus to act as transcription factors, have been studied extensively. The role of Smad3 in the transcriptional regulation of type I collagen gene expression and in the development of fibrosis, demonstrated both/n vitro and in animal models with a targeted deletion of Smad3, is of critical importance because it may lead to novel therapeutic strategies against these diseases. This review focuses on the mechanisms underlying Smad modulation of fibrillar collagen expression and how it relates to fibrotic processes.

Effects of Transplanting Nutrient Soil on Growth and Dry Matter Accumulation of Tobacco Seedlings

In order to select the suitable soil for transplanting tobacco in Hunan to- bacco growing areas, pot experiment was conducted to study the effects of different transplanting nutdent soils on the growth and dry matter accumulation of tobacco. The results indicated that the treatments of transplanting with nutrition soils were better than the control group. For the underground part, transplanting nutrient soil could effectively improve the root activity of tobacco plants, and increase root volume, root surface area, total root length, as well as the number of root tips and the number of root branches. For the aboveground part, transplanting nutrient soil could remarkably improve the plant height, stem girth, leaf number and maximum leaf area, and could simultaneously significantly increase the dry matter accumulation. By comparison, peat ＋ mushroom residue ＋ saw dust ＋ straw powder ＋ bicchar ＋ root promoting nutrient solution was the most effective treatment, and the effect of sole application of nutrient solution was limited. In conclusion, transplanting with nutrition soil could effectively promote the growth and dry matter accumulation of tobacco.

Tunable photonic microwave generated by multi-wavelength Brillouin fiber laser

Aimed at the problem of narrow tunability and low frequency microwave signal generated by the optical method,a novel approach to stabilizing the tunable photonic microwave generated by the multi-wavelength Brillouin fiber laser is proposed and is experimentally demonstrated.A singlelongitudinal-mode Brillouin fiber laser is designed,and by using the laser,a multi-wavelength Brillouin fiber laser with more than eleven orders of Stokes wave is observed.The wavelength spacing of the adjacent Stokes wave is 0.085 nm.If the Brillouin pump power is increased,the number of Stokes wave output can be further increased.The tunable microwave signals of 10.8 and 21.6 GHz are obtained by heterodyning the Rayleigh wave and Stokes wave of the multiwavelength Brillouin fiber laser.In the experiment,by tuning the pump wavelength and temperature of the gain fiber,microwave signals at different frequencies are generated.The tunable frequency range can be further expanded by using a temperature controller with a wider adjustment range,and the generated microwave signal exhibits high stability on frequency.

Study on Rooting of Strawberry Bechika

[Objective] The aim was to study rooting environment of strawberry ＂Bechi- ka＂ seedlings, and the somaclone domesticated transplanting was carded on. [Method] With the stem tip of stolon as material, the influence factom of rooting and the effects of different transplanting substrata on survival rate was investigated. [Result] The results showed that： 1/2MS was the best concentration for rooting and the rooting rate could reach 100%. IBA was better than IAA for rooting on growth regu- lator levdls, and it had the best effect on rooting with 0.3 mg/L, which produced the thickest and most-fibrous roots. Activated carbon had positive influences on the growth of roots, and the suitable concentration of activated carbon was 0.5 mg/l_ for rooting. The study found that survival rate of tissue culture seedlings was obviously higher in the combination of perlite and vermiculite than that in the combination of humus and sand, and the survival rate could reach 98.1% （perlite：vermiculite=l：l）. Seedlings in various transplanting substrata could normally bloom, fruit and form stolons. [Conclusion] The study provided technical support for achieving large-scale production of virus-free strawberry and quickly cultivating good seedlings.

Normal moveout for long offset in isotropic media using the Padé approximation

The nomaal moveout correction is important to long-offset observations, especially deep layers. For isotropic media, the conventional two-term approximation of the normal moveout function assumes a small offset-to-depth ratio and thus fails at large offset-to-depth ratios. We approximate the long-offset moveout using the Pade approximation. This method is superior to typical methods and flattens the seismic gathers over a wide range of offsets in multilayered media. For a four-layer model, traditional methods show traveltime errors of about 5 ms for offset-to-depth ratio of 2 and greater than 10 ms for offset-to-depth ratio of 3; in contrast, the maximum traveltime error for the [3, 3]-order Pade approximation is no more than 5 ms at offset-to-depth ratio of 3. For the Cooper Basin model, the maximum oft＇set-to-depth ratio for the [3, 3]-order Pade approximation is typically double of those in typical methods. The [7, 7]-order Pade approximation performs better than the [3.3]-order Pade armroximation.