Muscle spindles provide servo-assistance to jaw-closing muscles for chewing hard foods

The fundamental pattern of chewing induced by the network of neurons called central pattern generator has been reported to be modified by the information arising from the various oro-facial sensory receptors including muscle spindles of jaw closing muscles. The cell bodies of primary afferent neurons from these muscle spindles lie in mesencephalic trigeminal nucleus (MTN) in the brainstem. The aim of the study was to understand whether muscle spindles from jaw-closing muscles play any role in hard food chewing. Single neuronal discharge of muscle spindle afferents was recorded from the MTN simultaneous with jaw-movement and electromyograpic (EMG) activities of the left masseter (jaw-closing) muscle during chewing soft and hard foods (apple and pellet) in awake rabbits. Ten consecutive chewing cycles were taken for analysis. Discharge of nineteen muscle spindles from seven rabbits was successfully recorded. Muscle-spindle discharge was significantly higher during the closing phase of jaw-movement for the hard food chewing than for the soft food. The jaw-closing muscle EMG activity was significantly higher during hard food chewing compared to soft food. The spindle discharge was higher when the masseter muscle activity was greater for chewing hard food. Significant positive (r=0.822, p=<0.001) correlation was found between the difference of muscle activity between apple and pellet and the difference of spindle discharge between apple and pellet. Above findings suggest that the increase of spindle discharge during hard food chewing may play a role for facilitating jaw-closing muscle activities and thereby provides servo-assistance to jaw-closing muscles to compensate the hardness of food

Tea from the drinking to the synthesis of metal complexes and fabrication of PVA based polymer composites with controlled optical band gap

In the present study black tea extract (BTE) solution which is familiar for drinking was used to prepare cerium metal-complexes (Ce(III)-complex). The prepared Ce(III)-complex was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and UV–Vis spectroscopy. The results indicate that BTE solution is a novel green coordination chemistry approach for the synthesis of metal complexes. The outcomes signify that coordination occurs between cerium cations and polyphenols. The synthesis of metal-complexes with superior absorption performance in the visible region is a challenge for optoelectronic device applications. The suspended Ce(III)-complex in distilled water was mixed with poly (vinyl alcohol) (PVA) polymer to fabricate PVA/ Ce(III)-complex composites with controlled optical properties. The PVA/Ce(III)-complexes composite films were characterized by FTIR, XRD, and UV–Vis spectroscopy. The XRD findings confirms the amorphous structure for the synthesized Ce(III)-complexes. The addition of Ce(III)-complex into the PVA host polymer led to the growth of polymer composites with controllable small optical band gaps. It is shown by the FTIR spectra of the composite films that the functional groups of the host PVA have a vigorous interaction with the Ce(III)-complex. The XRD deconvolution on PVA composites reveals the amorphous phase enlargement with increasing Ce(III)-complex concentration. It is indicated in the atomic force microscopy (AFM) that the surface roughness in the doped PVA films increases with the increase of the Ce(III)-complex. There is a decrease in absorption edge from 5.7 to 1.7 eV. It becomes possible to recognize the type of electron transition by studying both the Tauc's model and optical dielectric loss (ɛi) parameter

Prevalence of blindness and low vision in Malaysian population: results from the National Eye Survey

ABSTRACT Background-A national eye survey was conducted in 1996 to determine the prevalence rates of blindness and low vision and their major causes among the Malaysian population of all ages. Methods-A stratified two-stage cluster sampling design was used to randomly select primary and secondary sampling units. Interviews, visual acuity tests and eye examinations on all individuals in the sampled households were performed. Estimates were weighted by factors adjusting for selection probability, non-response and sampling coverage. Results-The overall response rate was 69% (i.e. living quarters response rate was 72.8% and household response rate was 95.1%). The age-adjusted prevalence of bilateral blindness and low vision was 0.29% (95% CI 0.19-0.39%), and 2.44% (95% CI 2.18-2.69%) respectively. Females had a higher age adjusted prevalence of low vision compared to males. There was no significant difference in the prevalence of bilateral low vision and blindness among the four ethnic groups, and urban and rural residents. Cataract was the leading cause of blindness (39%), followed by retinal diseases (24%). Uncorrected refractive errors (48%) and cataract (36%) were the major causes of low vision. Conclusion-Malaysia has blindness and visual impairment rates, which were comparable to other countries in the South East Asia region. However, cataract and uncorrected refractive errors, though readily treatable, were still the leading causes of blindness, suggesting the need for an evaluation on accessibility and availability of eye care services and barriers to eye care utilization in the country

Muscle spindles provide servo-assistance to jaw-closing muscles for chewing hard foods

The fundamental pattern of chewing induced by the network of neurons called central pattern generator has been reported to be modified by the information arising from the various oro-facial sensory receptors including muscle spindles of jaw closing muscles. The cell bodies of primary afferent neurons from these muscle spindles lie in mesencephalic trigeminal nucleus (MTN) in the brainstem. The aim of the study was to understand whether muscle spindles from jaw-closing muscles play any role in hard food chewing. Single neuronal discharge of muscle spindle afferents was recorded from the MTN simultaneous with jaw-movement and electromyograpic (EMG) activities of the left masseter (jaw-closing) muscle during chewing soft and hard foods (apple and pellet) in awake rabbits. Ten consecutive chewing cycles were taken for analysis. Discharge of nineteen muscle spindles from seven rabbits was successfully recorded. Muscle-spindle discharge was significantly higher during the closing phase of jaw-movement for the hard food chewing than for the soft food. The jaw-closing muscle EMG activity was significantly higher during hard food chewing compared to soft food. The spindle discharge was higher when the masseter muscle activity was greater for chewing hard food. Significant positive (r=0.822, p=<0.001) correlation was found between the difference of muscle activity between apple and pellet and the difference of spindle discharge between apple and pellet. Above findings suggest that the increase of spindle discharge during hard food chewing may play a role for facilitating jaw-closing muscle activities and thereby provides servo-assistance to jaw-closing muscles to compensate the hardness of food

Flexible and biodegradable film for environmental friendly packaging material

Petroleum based packaging materials has been a problem due to its non-degradation nature. Polylactic acid is a polymer from renewable resources and has properties comparable to conventional plastics. Our research aims are to improve the general properties of PLA and reduce the cost of PLA by blending with starch as filler and epoxidized palm oil (EPO) as plasticizer. The PLA/starch/EPO blends were prepared by melt blending methods and their thermal and mechanical properties were investigated by Differential Screening Calorimetry (DSC) and Universal Tensile Machine (UTM)

Influence of multiwalled carbon nanotubes on biodegradable Poly(lactic acid) nanocomposites for electroactive shape memory actuator

Poly(lactic acid)/epoxidized soybean oil/carbon nanotubes (PLA/ESO/CNTs) nanocomposites were prepared by the solution blending process, and the influence of ESO on the properties of the composites was studied. Differential scanning calorimetry and X-ray diffraction revealed that the addition of CNTs improved the crystallinity of the nanocomposites. The modulus increased with the addition of CNTs content in the composites. Morphological characterizations were done by scanning electron microscopy and transmission electron microscopy. Electrical conductivity of PLA/ESO/CNT composites increased with the addition of CNTs. This study revealed that the addition of ESO facilitated the dispersion of the CNTs in the PLA matrix