Spidroin N-terminal domain forms amyloid-like fibril based hydrogels and provides a protein immobilization platform

Recombinant spider silks are of interest but the multimodal and aggregation-prone nature of them is a limitation. Here, the authors report on a miniature spidroin based on the N-terminal domain which forms a hydrogel at 37 degrees C which allows for ease of production and fusion protein modification to generate functional biomaterials.Recombinant spider silk proteins (spidroins) have multiple potential applications in development of novel biomaterials, but their multimodal and aggregation-prone nature have complicated production and straightforward applications. Here, we report that recombinant miniature spidroins, and importantly also the N-terminal domain (NT) on its own, rapidly form self-supporting and transparent hydrogels at 37 degrees C. The gelation is caused by NT alpha-helix to beta-sheet conversion and formation of amyloid-like fibrils, and fusion proteins composed of NT and green fluorescent protein or purine nucleoside phosphorylase form hydrogels with intact functions of the fusion moieties. Our findings demonstrate that recombinant NT and fusion proteins give high expression yields and bestow attractive properties to hydrogels, e.g., transparency, cross-linker free gelation and straightforward immobilization of active proteins at high density

Design and Implementation of High Gain Frequency Non-isolated DC Optimizers for Modular PV Application

In order to fulfill the increasing worldwide electricity demand, renewable energy sources have long been considered as a very attractive solution. Besides the shortage in the conventional energy sources, rising impact of the global warming and the climate change create the need for an alternative electricity supply with the lowest possible greenhouse gas emissions. Among the other renewable energy sources, photovoltaic (PV) energy is argued to be one of the most promising future clean energy source for its no carbon emission, pollution free operation, low maintenance cost, lack of noise and easy installation. Therefore, the PV energy has been foreseen as a major contributor in the worldwide electricity generation in a near future. Since 2010, the more PV capacity has been installed worldwide than in the previous four decades. The high demand and the several benefits of the PV technology brings the motivation for further research to utilize the solar power more efficiently. The PV research nowadays emphasis on improvement of the system efficiency over a wide range of operating conditions with more cost-effective way than the existing system. By following the trend, this PhD dissertation looks into an efficient way of the PV power conversion by designing and developing the novel power converters to improve the energy yield of the entire PV system. This dissertation proposes high efficient, compact, cost-effective DC-DC converters for the distributed PV application. In the PV power generation, the power loss due to the partial shading is a well-known problem in the prior art. It causes power mismatches between the PV outputs and reduces the total energy yield. To address the power mismatch problem and the fluctuations of the PV output, distributed PV power generations are considered as a potential solution. The benefits of the distributed power generation and the different types of configurations of that are discussed in this thesis. Among different options, DC-DC micro-converters (or also known as DC optimizers) are selected for further research as it is one of the most promising solution. Since DC distribution networks are newly emerging technology in the PV market, DC-DC micro-converters are also useful to integrate in a DC distribution system. In this work, two DC micro-converters are proposed for targeting two different applications, one is mainly for a series-connected distributed system and another is for a parallel-connected system. Another topology of a micro-converter is proposed, which is beneficial in terms of its wide input, output voltage range. It will help to track the generated PV power in a wide operating range. In order to deal with the PV output variations and the power mismatch problems, this work proposes the design requirements of a DC-DC micro-converter for the distributed PV application. These proposed requirements can be used as a guideline for the developments of a PV converter. By considering that, a non-isolated multiplier boost topology has been selected. The detail selection procedure and the suitability of the topology for this specific application are explained in the following chapters. A 200W high frequency non-isolated DC-DC converter is designed and built for the sub-module level power conversion, mainly for a series-connected system. Since it is a high frequency converter, few measures are taken into account during the development of the converter. The different steps from design to implementation are described in detail in the thesis. The measurement result of the converter performance, efficiency measurement results at full power range and the thermal measurement results are provided here. The converter is further tested with the high band gap gallium nitride (GaN) switches in order to investigate the efficiency improvement of the converter. Next to that, a wide input range, high gain, high efficiency non-isolated converter is developed to use as a module-integrated converter for the parallel-connected system. The converter is made to interface between a PV module and a DC bus as it can directly boost from the low PV voltage to a high DC bus voltage (360V). The converter is further integrated in a real-time PV system set-up and tested under static and dynamic irradiance for the different operating conditions. Finally, a novel DC-DC converter’s topology is proposed for a wide input, output voltage range. Different novel ideas are proposed to increase the voltage gain range and the input-output voltage range of a non-isolated multiplier converter. This topology is applicable for any kind of fluctuating voltage sources. All the presented converters are proposed to facilitate the PV energy harvesting and to increase the overall energy yield of a PV system.status: publishe

INTRA-MODULE DC-DC CONVERTER: TOPOLOGY SELECTION AND ANALYSIS

ABSTRACT: In this paper, firstly the effect of partial shading on output power of a photovoltaic system is discussed and the limitations of a centralized power conversion for extenuation that problem is described. Here, the aim is to discuss the limitations of the state-of-art power conversion system and to analyze the possible solutions. The benefits of the distributed power conversion in terms of overall photovoltaic system efficiency are explored. This work presents the requirements of the intra-module converter in photovoltaic system and also discusses the different factors that need to consider while implementing a DC-DC converter as an intra-module converter. A topology of high gain DC-DC converter is presented here, which can be used in photovoltaic applications as an intra-module converter. This paper also demonstrates the suitability of this presented converter in photovoltaic applications. Simulation results of the proposed converter are also presented here.status: publishe

Advances in early diagnosis of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most recurrent hepatic malignancy and the third in the cancer-related casualties in the west. The frequently-documented causes of HCC are chronic liver infections by hepatitis B virus or hepatitis C virus, nonalcoholic fatty liver disease, cirrhosis, exposure to aflatoxins and tobacco smocking, etc. Clinical presentation of this fatal disease ranges from asymptomatic to upper abdominal pain or common health conditions like weight loss or lethargy. Among current surveillance strategy for suspected patients, liver imaging and serum alpha fetoprotein estimation has been regularly recommended. However, sensitivity of this diagnostic methodology especially in early detections, often suffers from compromised sensitivity and selectivity. Various image based and serological biomarkers for HCC has been introduced in recent decades with varied sensitivity as stand-alone or combined diagnostic protocol. The current article will review the status of HCC diagnosis with respect to common diagnostic protocol, and upcoming novel biomarkers

Role of pepsin in modifying the allergenicity of Bhetki (Lates calcarifer) and Mackerel (Rastrelliger kanagurta) fish

94-100The effect of pepsin digestion on the allergenicity of raw and thermally processed (boiled and fried) fish muscle extracts of two widely consumed fishes bhetki (Lates calcarifer) and mackerel (Rastrelliger kanagurta) was studied. Sere were collected from 110 patients who were hypersensitive to fish, as evidenced by their clinical history, symptoms and positive skin-prick test results. The various extracts after digestion with pepsin at different times of incubation were tested for specific IgE-binding activity by ELISA and immunoblotting with patients’ sera. All the extracts of both the fishes retained their allergenicity as evidenced by ELISA and immunoblotting. In bhetki, maximum allergenicity was found in the pepsin-digested fried extract, whereas similar treatment decreased the allergenicity in fried mackerel. Results showed that raw as well as thermally processed allergens of both the fishes maintained strong allergenicity, even after digestion with pepsin for different time periods. The study revealed that the fish proteins played an important role in manifestation of allergy, due to their stable structure, which was retained even after pepsin and heat treatment

Design of an Intra-module DC-DC Converter for PV Application: Design Considerations and Prototype

© 2014 IEEE. The effective efficiency of a photovoltaic system is strongly affected by varying factors such as partial shading. The centralized power conversion has limitations to mitigate that problem. As a possible solution the benefits of the distributed power conversion are explored and as an integral part of distributed power conversion an intra-module DC-DC converter is presented here to implement at substring level in photovoltaic application. In this work, the design requirements of the intra-module converter are identified and the converter is designed accordingly. The effectiveness of the designed converter is also discussed in this paper. Finally, a fully-working prototype of this converter is built and tested.status: publishe

Identification of allergens in Indian fishes: Hilsa and Pomfret exemplified by ELISA and immunoblotting

1170-1175Enzymed-linked immunosorbant assay of hilsa and pomfret muscle extracts showed specific IgE binding to ten allergic patients' sera, the results corroborated to that of skin prick test. Comparison of allergen profiles of the two fish extracts by immunoblotting revealed a common antigenic protein of 50 kDa and some high molecular weight fish allergens instead of low molecular weight parvalbumin found in several fishes. Purified and well characterized fish allergens are always considered better than crude fish extracts for diagnostic use

Artificial spider silk supports and guides neurite extension in vitro

Surgical intervention with the use of autografts is considered the gold standard to treat peripheral nerve injuries. However, a biomaterial that supports and guides nerve growth would be an attractive alternative to overcome problems with limited availability, morbidity at the site of harvest, and nerve mismatches related to autografts. Native spider silk is a promising material for construction of nerve guidance conduit (NGC), as it enables regeneration of cm-long nerve injuries in sheep, but regulatory requirements for medical devices demand synthetic materials. Here, we use a recombinant spider silk protein (NT2RepCT) and a functionalized variant carrying a peptide derived from vitronectin (VN-NT2RepCT) as substrates for nerve growth support and neurite extension, using a dorsal root ganglion cell line, ND7/23. Two-dimensional coatings were benchmarked against poly-d-lysine and recombinant laminins. Both spider silk coatings performed as the control substrates with regards to proliferation, survival, and neurite growth. Furthermore, NT2RepCT and VN-NT2RepCT spun into continuous fibers in a biomimetic spinning set-up support cell survival, neurite growth, and guidance to an even larger extent than native spider silk. Thus, artificial spider silk is a promising biomaterial for development of NGCs

Antiproliferative effect of T/Tn specific Artocarpus lakoocha agglutinin (ALA) on human leukemic cells (Jurkat, U937, K562) and their imaging by QD-ALA nanoconjugate

T/Tn specificity of Artocarpus lakoocha agglutinin (ALA), isolated from the seeds of A. lakoocha (Moraceae) fruit and a heterodimer (16 kD and 12 kD) of molecular mass 28 kD, was further confirmed by SPR analysis using T/Tn glycan containing mammalian glycoproteins. N-terminal amino acid sequence analysis of ALA showed homology at 15, 19-21, 24-27, and 29 residues with other lectin members of Moraceae family viz., Artocarpus integrifolia (jacalin) lectin, Artocarpus hirsuta lectin, and Maclura pomifera agglutinin. It is mitogenic to human PBMC and the maximum proliferation was observed at 1 ng/ml. It showed an antiproliferative effect on leukemic cells, with the highest effect toward Jurkat cells (IC50 13.15 ng/ml). Synthesized CdS quantum dot-ALA nanoconjugate was employed to detect the expression of T/Tn glycans on Jurkat, U937, and K562 leukemic cells surfaces as well as normal lymphocytes by fluorescence microscopy. No green fluorescence was observed with normal lymphocytes indicating that T/Tn determinants, which are recognized as human tumor associated structures were cryptic on normal lymphocyte surfaces, whereas intense green fluorescent dots appeared during imaging of leukemic cells, where such determinants were present in unmasked form. The above results indicated that QD-ALA nanoconjugate is an efficient fluorescent marker for identification of leukemic cell lines that gives rise to high quality images