Self-referencing photothermal digital holographic microscope for characterization of low-loss liquids

Measurement of absorption coefficients of transparent samples is important for their characterization and identification; however, it is challenging to measure low values, e.g., 10−3–10−4 cm−1 with high accuracy. Here, we report a compact photothermal lateral shearing digital holographic device. It is based on the thermal lens effect and a common-path, self-referencing digital holographic microscope comprising a glass plate, probe beam, and a CMOS camera. The change in phase distribution caused by the temperature change due to light absorption is measured from the recorded holograms to extract the sample's absorbance and absorption coefficient. The feasibility of the proposed configuration is validated by the experimental results obtained with different concentrations of gold nanoparticles (AuNPs) in an aqueous solution. Determination of AuNPs concentration in the nM range is performed, and the obtained limits of detection and quantitation are 0.04 nM and 0.13, respectively. The calibration curve is linear at a low concentration range of 0.06–0.95 nM with 1% reproducibility. In addition, the method's versatility is demonstrated by measuring the absorption coefficient of low-loss solvents, such as ethanol and water. The determined absorption coefficients agree with the reported values, confirming that this method provides good spectrometric capabilities, such as high sensitivity and accuracy

The use of mesenchymal stem cells for cartilage repair and regeneration: a systematic review.

BACKGROUND: The management of articular cartilage defects presents many clinical challenges due to its avascular, aneural and alymphatic nature. Bone marrow stimulation techniques, such as microfracture, are the most frequently used method in clinical practice however the resulting mixed fibrocartilage tissue which is inferior to native hyaline cartilage. Other methods have shown promise but are far from perfect. There is an unmet need and growing interest in regenerative medicine and tissue engineering to improve the outcome for patients requiring cartilage repair. Many published reviews on cartilage repair only list human clinical trials, underestimating the wealth of basic sciences and animal studies that are precursors to future research. We therefore set out to perform a systematic review of the literature to assess the translation of stem cell therapy to explore what research had been carried out at each of the stages of translation from bench-top (in vitro), animal (pre-clinical) and human studies (clinical) and assemble an evidence-based cascade for the responsible introduction of stem cell therapy for cartilage defects. This review was conducted in accordance to PRISMA guidelines using CINHAL, MEDLINE, EMBASE, Scopus and Web of Knowledge databases from 1st January 1900 to 30th June 2015. In total, there were 2880 studies identified of which 252 studies were included for analysis (100 articles for in vitro studies, 111 studies for animal studies; and 31 studies for human studies). There was a huge variance in cell source in pre-clinical studies both of terms of animal used, location of harvest (fat, marrow, blood or synovium) and allogeneicity. The use of scaffolds, growth factors, number of cell passages and number of cells used was hugely heterogeneous. SHORT CONCLUSIONS: This review offers a comprehensive assessment of the evidence behind the translation of basic science to the clinical practice of cartilage repair. It has revealed a lack of connectivity between the in vitro, pre-clinical and human data and a patchwork quilt of synergistic evidence. Drivers for progress in this space are largely driven by patient demand, surgeon inquisition and a regulatory framework that is learning at the same pace as new developments take place

A preliminary study comparing the use of allogenic chondrogenic pre-differentiated and undifferentiated mesenchymal stem cells for the repair of full thickness articular cartilage defects in Rabbits

Chondrogenic differentiated mesenchymal stem cells (CMSCs) have been shown to produce superior chondrogenic expression markers in vitro. However, the use of these cells in vivo has not been fully explored. In this study, in vivo assessment of cartilage repair potential between allogenic-derived chondrogenic pre-differentiated mesenchymal stem cells and undifferentiated MSCs (MSCs) were compared. Bilateral full thickness cartilage defects were created on the medial femoral condyles of 12 rabbits (n = 12). Rabbits were divided into two groups. In one group, the defects in the right knees were repaired using alginate encapsulated MSCs while in the second group, CMSCs were used. The animals were sacrificed and the repaired and control knees were assessed at 3 and 6 months after implantation. Quantitative analysis was performed by measuring the Glycosaminoglycans (GAGs)/total protein content. The mean Brittberg score was higher in the transplanted knees as compared to the untreated knee at 6 months (p 0.05). This study demonstrates that the use of either MSC or CMSC produced superior healing when compared to cartilage defects that were untreated. However, both cells produced comparable treatment outcomes. (C) 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29: 1336-1342, 201

Neural Network-Based Adaptive PID Controller Design for Over-Frequency Control in Microgrid Using Honey Badger Algorithm

Secondary frequency control systems, such as Automatic Generation Control (AGC), are used in interconnected power grids. However, when a system failure causes systems to separate into zones (islands), AGC can no longer be used, and the primary frequency control is the only control available. Moreover, load changes may cause frequency drop in some areas and over-frequency in other areas. Therefore, the goal in this article will be to design a neural network-based proportional, integral, and derivative (PID) controller in the primary control architecture to control the over frequency condition. The proposed controller is adaptively optimized in two stages by the honey badger algorithm (HBA). In the first stage, the PID controller gain values are optimized by the HBA algorithm for different values of load loss. While in the second stage, a feed-forward artificial neural network (ANN) is trained to match the tie-line measured power to the corresponding optimized HBA-PID gains obtained in the first stage. Finally, the proposed controller is implemented on a two-area interconnected thermal power system. The proposed controller results qualitatively outperform one of the best tuning methods, the Ziegler-Nichols (ZN) approach, and they show that the proposed controller has better dynamic responses with minimal frequency deviations and fast settling time, creating and guaranteeing a margin of stability for the closed loop

Magnetic graphene/Ni-nano-crystal hybrid for small field magnetoresistive effect synthesized via electrochemical exfoliation/deposition technique

Two-dimensional heterostructures of graphene (Gr) and metal/semiconducting elements convey new direction in electronic devices. They can be useful for spintronics because of small spin orbit interaction of Gr as a non-magnetic metal host with promising electrochemical stability. In this paper, we demonstrate one-step fabrication of magnetic Ni-particles entrapped within Gr-flakes based on simultaneous electrochemical exfoliation/deposition procedure by two-electrode system using platinum as the cathode electrode and a graphite foil as the anode electrode. The final product is an air stable hybrid element including Gr flakes hosting magnetic Ni-nano-crystals showing superparamagnetic-like response and room temperature giant magnetoresistance (GMR) effect at small magnetic field range. The GMR effect is originated from spin scattering through ferromagnetic/non-magnetic nature of Ni/Gr heterostructure and interpreted based on a phenomenological spin transport model. Our work benefits from XRD, XPS, Raman, TEM, FTIR and VSM measurements We addressed that how our results can be used for rapid manufacturing of magnetic Gr for low field magneto resistive elements and potential printed spintronic devices.</p