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1.
The glycemia-sensitive neuron in lateral hypothalamic area (LHA) is one of the important central neural events involved in the feeding control.Electrophysio-logical studies have demonstrated that gastrointestinal vagal afferent inputs could convey the meal-related infomation of gastrointestinal tract to the hypothalamus,In this study ,we examined whether the gastric vagal afferent inputs could reach the glycemia-sensitive neurons of the LHA by using in vivo extracelluar recording technique in the rat.The results showed that stimulation of gastric vagal nerves elictied two types of the LHA neurons responses:the phasic response (93/116,80.2%),and the change in cell‘s firing pattern (23/116,19.3%) ,Within the 93 cells that responded to the gastric vagal stimulation with a phasic response ,67(72.0%) showed an inhibition in the cell‘s firing rate 26(27.4%) were excited,Of the 23 cells that showed a change in the firing pattern 13 responded to the gastric vagal stimulation with a long-lasting increase or decrease in firing rate,the remaining 10 cells turned thier discrete spiking to the bust discharging .In addition ,of 101 LHA neurons including the ypes of responsive neurons,73(72.3%)were identified to be glycemia-sensitive neurons,These results demonstrated that the gastric vagal afferent inputs could reach the LHA and predominaltly reach those glycemia-seach neurons in the LHA ,Presumably,the modulation of glycemia-sensitive neurons of LHA by the gastric vagal afferent inputs may play an important role in the short-term regulation of feeding behavior.  相似文献   

2.
The effects of stimulating locus coeruleus (LC) on neuronal activity of cerebellar fastigial nucleus (FN) was investigated. Stimulation of LC elicited inhibitory, excitatory and biphasic (inhibition-excitation) responses from FN cells. The majority of responsive cells showed an inhibitory response with a latency of less than 10 ms. Injection of α adrenoreceptor antagonists phentolamine (ⅳ) could block the inhibitory response of FN cells to the LC stimulation, but propranolol (ⅳ), a β adrenoreceptor antagonist, could not. These results suggest that LC-cerebellar noradrenergic afferent fibers may be involved in the cerebellar sensorimotor integration process by exerting their modulatory action on the cerebellar nuclear cells' activities.  相似文献   

3.
Histological and physiological studies indicated that most skeletal muscles can be divided into a series of relatively independent sub-volumes: "neuromuscular compartments" and the partitioning property of the muscle result in the localization of muscle reflex. In the present experiment we studied the recruitment properties of medial gastracnemius (MG) muscle motoneuron pool of decerebrate cat with two kinds of local mechanical stimulation: local stretch and acupuncture-like stimuli. The results indicate that: (ⅰ) there is an obvious property of localization of recruitment activity, only the MNs which innervate the stimulated compartment were recruited by weaker and shorter stimuli; (ⅱ) recruitment activity spread to those MNs which supply the adjacent and distal compartments during the strength of stimulation or duration of the stimulation was increased; and (ⅲ) the recruitment property of muscle activity elicited by the local mechanical stimulation is thought similar to that of "needle feeling" along the meridian pathway during stimulation of acupuncture point.  相似文献   

4.
A chitosan tube filled with alginate fibers was implanted into the injured spinal cord of a rat for repairing the damaged tissue. Twelve months after the operation, the morphological observation demonstrated that this chitosan tube could induce regeneration of myelinated and non-myelinated axons and blood vessels. The Basso-Beattie-Bresnahan (BBB) behavioral evaluation confirmed that the implants played a key role in the long-term restoration of rats motor functions. It is a promising start in the treatment of the patients with the injury of the spinal cord.  相似文献   

5.
Orphanin FQ (OFQ) is a new modulatory peptide which was found in 1994. It mediates in morphine analgesia and electroacupuncture analgesia. The interaction between OFQ and 5-hydroxytryptamine (5-HT) on analgesia was observed using the method of intracere-broventricular microinjection. The results showed that cumulative i. c. v. administration of gradually increasing doses of 5-HT produced a dose-dependent analgesia, and administration of different doses of OFQ separateness had no significant effect on tail flick latency, but 1 or 10 μg OFQ could reverse the analgesia induced by 5-HT, suggesting that OFQ could antagonize the analgesia induced by 5-HT in rat brain.  相似文献   

6.
Generally there are three kinds of substances used as negative-ion generator in textiles, natural silicate minerals (ceramic/tourmaline), natural rare-earth minerals and natural sediment with ultra-fine pores. Based on different additive, the mechanism of negative-ion generation is largely divided into three kinds, the piezoelectricity and pyroelectricity of tourmaline crystal, air ionization caused by low-level radiation and breaking up of the clusters of moisture in air when going through the ultra-free pores of natural sediment. In this paper, the negative-ion generating properties of natural fiber fabrics-cctton, wool, silk and linen were first proposed. By some kind of physical stimulation, rubbing or vibrating, natural fiber fabrics without any additive could also emit negative ions. Considering that the piezoelectric effect was observed in wool fibers, silk fibers and cellulose fibers, the piezoelectricity was studied as a mechanism of negative-ion generation of natural fiber fabrics. Another possible mechanism was the tribeelectricity produced by the sense of ntbbtng or vibrating and tip discharge of hairiness. The Final experiment results verified that the latter would be the main reason, and the electrolytic dissociation of moisture was also contributing to negative-ion generation.  相似文献   

7.
The aim of this study is to determine whether myeloma and lymphoma tumor cells can function as efficient antigen presenting cells (APC) to enhance the co-stimulation of T cells. The expression and function of T cell activation-related molecules, especially CD80, CD28, CD40 and CD40 ligand (CD40L), were studied on nine human myeloma cell lines (HMCL) and two B lymphoma cell lines. In the case of myeloma cell lines, the cells generally lacked CD80 antigen and expressed a heterogeneous CD40, and the expressions of CD40 and CD80 molecules could not be induced by either CD28 stimulation or CD40 ligation. Conversely, in the two B lymphoma cell lines, tumor cells expressed both CD80 and CD40 to some extent. CD28 stimulation could obviously increase the expression of CD80, CD40 and some adhesion molecules, and therefore generate a more efficient anti- tumor cell immunity. In conclusion, CD28 stimulation combined with CD40 antibody or soluble CD40 ligand may be a promising immunotherapeutic approach to B lymphoma.  相似文献   

8.
Electrospinning is a well-known process for producing submicrometer fibers, which have wide applications in many fields, especially in tissue engineering scaffolds and drug-delivery systems. This paper presents the formation of drug-loaded electrospun twin fibers. The correlations between the twin fiber formation and the polymer materials or the loaded drugs were studied by using poly(l-lactide) and poly(l-lactide-co-glycolide) as electrospinning materials, and rifampin and paclitaxel as loaded drugs. Scanning electron microscopy showed that the formation of twin fibers is significantly affected by the loaded drug but not the polymer material. A possible reason for twin fiber formation was analyzed.  相似文献   

9.
Polyacrylonitrile(PAN), PAN/cellulose acetate(CA), and PAN/CA-Ag based activated carbon nanofiber(ACNF) were prepared using electrostatic spinning and further heat treatment. Thermogravimetry–differential scanning calorimetry(TG–DSC) analysis indicated that the addition of CA or Ag did not have a significant impact on the thermal decomposition of PAN materials but the yields of fibers could be improved. Scanning electron microscopy(SEM) analysis showed that the micromorphologies of produced fibers were greatly influenced by the viscosity and conductivity of precursor solutions. Fourier transform infrared spectroscopy(FT-IR) analysis proved that a cyclized or trapezoidal structure could form and the carbon scaffold composed of C=C bonds appeared in the PAN-based ACNFs. The characteristic diffraction peaks in X-ray diffraction(XRD) spectra were the evidence of a turbostratic structure and silver existed in the PAN/CA-Ag based ACNF. Brunner–Emmett–Teller(BET) analysis showed that the doping of CA and Ag increased surface area and micropore volume of fibers; particularly, PAN/CA-Ag based ACNF exhibited the best porosity feature. Furthermore, SO2 adsorption experiments indicated that all the three fibers had good adsorption effects on lower concentrations of SO2 at room temperature; especially, the PAN/CA-Ag based ACNF showed the best adsorption performance, and it may be one of the most promising adsorbents used in the fields of chemical industry and environment protection.  相似文献   

10.
A new type of alkali-soluble polyester/cotton blended yarns was used to knit a compact knitted fabric on a circular weft knitting machine,treated with 5 g/L Na OH solution for 60 min at a temperature of 100 ℃,and the polyester was completely dissolved. The dissolved polyester could be polymerized again by a polycondensation reaction.After the cotton fibers were opened and combed,the length and mechanical properties of the cotton fibers were tested.The physical and mechanical properties of the separated cotton fibers were good. The chemical structure and crystallinity were analyzed by Fourier transform infrared( FTIR) spectroscopy and X-ray diffraction( XRD) analysis.It could be seen that the chemical structure of cotton fibers was almost unchanged after treatment,and the crystallinity decreased slightly. It provides some reference for the separation and recycling of waste polyester/cotton fabrics.  相似文献   

11.
In this study, we investigated the features of latency-amplitude (L-A) functions at different sound frequencies, using extracellular recording from auditory neurons in the central nucleus of the inferior colliculus (ICC) in mice. Isofrequency L-A functions from single neurons could be fit with a newly developed equation based on Pieron’s law. The high degree of fitness indicates that the curvatures of all isofrequency L-A functions for a given neuron are similar, and that the difference between L-A functions is due to a shift in their positions in the coordinate system. When we normalized the L-A functions to match the position of the L-A function obtained at the neuronal characteristic frequency (CF), all isofrequency L-A functions from a given ICC neuron were highly superimposed. The similar shapes of the L-A functions at different frequencies may reflect the physical laws of sound being transferred into bioelectric signals. The position of a non-CF L-A function could be measured as the differences of the asymptotic L and A ( L and A) compared to the L-A function at a reference frequency such as the CF. The nerve fibers and synapses connecting to a neuron for acoustic information processing can be functionally simplified as a single "wire" (as the total length of nerve fibers) and "joint" (as the summated size/strength of synapses). The wire and joint mediate information transmission and transduction, respectively. Thus, L and A may be measurements of the total length of nerve fibers and the strength of summated synapses in the activated auditory pathway. L and A differed between frequency channels and neurons, suggesting that the differences of acoustic neuronal responses are always caused by activation of different pathways, and that the pathways that process sounds are diverse.  相似文献   

12.
Polypropylene superfine fibers or cell porous fibers were prepared from the bi-component blend fibers of polypropylene/easlly hydro-degraded polyester(PP/EHDPET)by alkaline hydrolysis process. EHDPET is a kind of copolyester that can be rapidly hydro-degraded in the hot alkaline solution. This paper discussed the kinetics of alkaline hydrolysis of EHDPET, and the effect of catalyst, bulk ratio and the content of polypropylene grafted maleic anhydride (PP-g-MAH) on the alkaline hydrolysis process. Meanwhile, the morphological change of the outer surface of blend fibers during this process was also investigated by the technology of scanning electron microscope (SEM).  相似文献   

13.
The corn husks were usually discarded as useless materials,after alkali treatment from which the corn husk fiber was obtained. The corn husk fiber included half degumming corn husk bundle fiber and corn husk single fiber. This study found that corn husk single fiber was a kind of cellulose fiber,and was obtained with the fully alkali treatment technique,the process of which was NaOH concentration 0.15 g/mL,temperature at 80℃,and reaction time about 2.5 h. The morphologies of corn husk single fibers presented nature convolutions along with the fiber axis. They were closed at both ends,and they had a pentagram cavity and oval-shaped crosssection. They were flat shape,the fineness of the fibers was close to cotton fiber,and the mechanical properties of the fibers were similar to hemp fiber. So the corn husk fibers could be predicted that they could be used in textile industry because their properties were very close to cotton fiber or flax fiber.  相似文献   

14.
Composites are composed of multiphase materials, where each phase has specific properties that differ from those of the other phases which can effect on the whole properties of composite. Nanocomposites are class of materials that contain at least one phase in the nanometric size range and can be produced by any suitable technique for preparing nanomaterials. Composites are an interesting class of materials that have recently been used in numerous applications, including structural, biomedical, electronics, and environmental applications. In composites, reinforcements might be fibers, particulates, or whiskers. Mechanical alloying (MA) is a promising technique for producing nanocomposite materials that are difficult or impossible to prepare via conventional techniques. In this review, we provide an overview of nanocomposites prepared by the MA process. The mechanism of milling and other milling parameters are overviewed, and insights into sintering categories and parameters are also presented.  相似文献   

15.
Carbon fiber-reinforced SiC composites were prepared by precursor pyrolysis-hot pressing (PP-HP) and precursor impregnation-pyrolysis (PIP), respectively. The effect of fabrication methods on the microstructure and mechanical properties of the composites was investigated. It was found that the composite prepared by PP-HP exhibits a brittle fracture behavior, which is mainly ascribed to a strongly bonded fiber/matrix interface and the degradation of the fibers caused by a higher processing temperature. On the contrary, the composite prepared by PIP shows a tough fracture behavior, which could be rationalized on the basis of a weakly bonded fiber/matrix interface as well as a higher strength retention of the fibers. As a result, in comparison with the composite prepared by PP-HP, the composite prepared by PIP achieves better mechanical properties with a flexural strength of 573.4 MPa and a fracture toughness of 17.2 MPa·m1/2.  相似文献   

16.
The crystallization properties and morphology structure of the cationic dyeable polypropylene fibers which were produced by the blending spinning method were studied by making use of X-ray and scanning electron microscopy (SEM). It comes to the conclusions that the larger the crystallite size in the fibers is , the better the dycable properties of the fibers are and there is a little compatibility between the dyeable agent and polypropylene resin. And the dye-uptake of the fibers may be up to 90% because the dyeable agent can uniformly be scattered in polypropylene.  相似文献   

17.
Stimulated Brillouin scattering in optical fibers is described by a theoretical model and numerical analysis. The results showed that, for an optical fiber pumped by a laser beam with ns-order-pulse width and kW-order peak-power, SBS reflectivity tends to saturate when the fiber length exceeds a limit, named “effective fiber length“. Using small core-diameter and long enough fiber, the SBS reflectivity level could be raised but is limited by optical damage of the entrance surface of the fiber. Therefore, just a small dynamic range can be obtained.  相似文献   

18.
Some Problems of Rails For High-speed Railway of China   总被引:1,自引:0,他引:1  
Acciording to running experience of high-speed railway abroad,a full attention must be paid to some requirements of specifica-tion of rails for high-speed railway,such as materil mechanical properties,rimension tolernces,straightness,surface flatness and so on.It is suggested that the long-length rails should be laid in high-speed railway,and the feasibility of producing,welding and transporting of long-length rails should be researched.On the basis of technical innovation of domestic manufacturers,it is practicable to lay 50-100mlong-length rails should be researched.On the basis of producing,welding and transporting of long-length homemade rails in high-speed railway of China.The following welding programme of rails for hiah-speed railway can be adiop-ted:50-100m long-lenath rails can be welded as 500m long rail string through flash butt welding in plant,then in field the reid string can be welded through a mobile flash butt welding or thermit welding.As the specification of rails or high-seed railway is rigorous.some related techniques to long-length rails should be researched and practised as soon as possible,including mobile flash butt welding tech-nique,transporting and reinforcing techniques of lon-length rails,etc…  相似文献   

19.
The dynamic observation of the fracture processes of PET(polyethylene terephthalate)andPAN(polyacrylonitrile)fibers in tension was carried out under a scanning electron microscope.Thestepwisc micrographs taken revealed the features of crack initiation and crack growth and of thefailure of the fibers.The fracture behaviour of PET fibers in tension is characterized by theoccurence of shear bands,which initiate a crack whose development leads to the final failure of afiber.For tensile PAN fibers,a high concentration of cracks are initiate in the skin of a fiber,andthen a few or one of them develop themselves by way of pulse and lead to the final failure of the fi-ber.  相似文献   

20.
Here we report a combustion endstation at National Synchrotron Radiation Laboratory (NSRL) and some primary experimental results. Synchrotron radiation can provide the tunable vacuum ultraviolet (VUV) photon with the high intensity and the good collimation. VUV photoioni-ation is a single-photon ionization process. Combined with molecular-beam mass spectrometry (MBMS), the VUV single-photon ionization can be applied to detect the combustion products, especially the intermediates and free radicals produced from combustion process. This method is proved to be a powerful tool for combustion study, which could be helpful for developing combustion kinetic models and understanding the mechanism of combustion reactions.  相似文献   

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