Quantitative Phase Imaging Camera With a Weak Diffuser

We introduce the quantitative phase imaging camera with a weak diffuser (QPICWD) as an effective scheme of quantitative phase imaging (QPI) based on normal microscope platforms. The QPICWD is an independent compact camera measuring object induced phase delay under low-coherence quasi-monochromatic illumination by examining the deformation of the speckle intensity pattern. By interpreting the speckle deformation with an ensemble average of the geometric flow, we can obtain the high-resolution distortion field via the transport of intensity equation (TIE). Since the phase measured by TIE is the generalized phase of the partially coherent image, rather than the phase of the measured object, we analyze the effect of illumination coherence and imaging numerical aperture (NA) on the accuracy of phase retrieval, revealing that the sample's phase can be reliably reconstructed under the conditions that the coherence parameter (the ratio of illumination NA to objective NA) of the Köhler illumination is between 0.3 and 0.5. We present some applications for the proposed design involving nondestructive optical testing of microlens array with nanometric thickness and imaging of fixed and live unstained HeLa cells. Since the designed QPI camera does not require any modification of the widely available bright-field microscope or additional accessories for its use, it is expected to be applied by the broader communities of biology and medicine

Engineering of silk fibroin : from nanofibers to nanofibrous scaffolds for biomedical application

&nbsp;Nanofibers and nanofibrous scaffolds with hierarchical aligned structures are constructed by self-assembly and phase separation. As-prepared nanofibrous materials show a specifically high capacity in cell capture and promoting proliferation of cells. More interestingly, the nanofibrous materials can direct HUVECs to assemble into vessel-like structure and 3D growth of DRG neurites.<br /

Facile synthesis of silver submicrospheres and their applications

Uniform silver submicrospheres were synthesized under ambient conditions, through reduction of silver nitrate using ascorbic acid as a reducing agent and Tween 20 as a stabilizer. The silver submicroparticles exhibited strong catalytic activity for the reduction of 4-nitrophenol by sodium borohydride (NaBH4). Significantly, the aggregates of a few silver submicroparticles can be used as surface-enhanced Raman scattering (SERS) substrate to improve markedly the Raman signal of crystal violet. The morphologies of silver submicroparticles can be controlled by changing reaction conditions. The formation process of silver submicroparticles was monitored by time-resolved extinction spectroscopy. The influences of concentrations and molar ratios of reaction reagents on the formation of silver submicroparticles are discussed

Silk patterns made by direct femtosecond laser writing

Silk patterns in a film of amorphous water-soluble fibroin are created by tailored exposure to femtosecond-laser pulses (1030&thinsp;nm/230&thinsp;fs) without the use of photo-initiators. This shows that amorphous silk can be used as a negative tone photo-resist. It is also shown that water insoluble crystalline silk films can be precisely ablated from a glass substrate achieving the patterns of crystalline silk gratings on a glass substrate. Bio-compatible/degradable silk can be laser structured to achieve conformational transformations as demonstrated by infrared spectroscopy

Neuroplasticity Changes on Human Motor Cortex Induced by Acupuncture Therapy: A Preliminary Study

While neuroplasticity changes measured by transcranial magnetic stimulation have been proved to be highly correlated to motor recovery and have been tested in various forms of interventions, it has not been applied to investigate the neurophysiologic mechanism of acupuncture therapy. The aim of this study is to investigate neuroplasticity changes induced by a single session of acupuncture therapy in healthy adults, regarding the excitability change on bilateral primary motor cortex and interhemispheric inhibition. Ten subjects took a 30-minute acupuncture therapy and the same length relaxing phase in separate days. Transcranial magnetic stimulation measures, including resting motor threshold, amplitudes of motor-evoked potential, and interhemispheric inhibition, were assessed before and 10 minutes after intervention. Acupuncture treatment showed significant changes on potential amplitude from both ipsilateral and contralateral hemispheres to acupuncture compared to baseline. Also, interhemispheric inhibition from the contralateral motor cortex to the opposite showed a significant decline. The results indicated that corticomotoneuronal excitability and interhemispheric competition could be modulated by acupuncture therapy on healthy subjects. The following question about whether these changes will be observed in the same way on stroke patients and whether they correlate with the therapeutic effect on movement need to be answered by following studies. This trial is registered with ISRCTN13074245