Helix Coils Research Articles

In-vitro antimicrobial activity of AF-DP protein and in-silico approach of cell membrane disruption

Microbial resistance against common antibiotics has become one of the most serious threats to human health. The increasing statistics on this problem show the necessity of finding a way to deal with it. In recent years, antimicrobial peptides with unique properties and the capability of targeting a wide range of pathogens, have been considered as a potential for replacing common antibiotics. A small chitin-binding protein with anticandidal activity was isolated from Moringa oleifera seeds by Neto and colleagues in 2017, which very much resembled antimicrobial peptides. In this study, the antimicrobial protein ‘AF-DP’ was identified and characterized. AF-DP was heterologously expressed, purified, and characterized, and its 3D structure was predicted. Six molecular dynamic simulations were performed to investigate how the protein interacts with Gram-negative inner and outer, Gram-positive, fungal, cancerous, and normal mammalian membranes. Also, its antimicrobial and anticancer activity was assessed in vitro via minimum inhibition concentration (MIC) and MTT assays, respectively. This protein with 111 amino acids and a total net charge (of 10.5) has been predicted to be mainly composed of alpha helix and random coils. Its MIC affecting the growth of Escherichia coli, Staphylococcus aureus, and Candida albicans was 30 µg/ml, 100 µg/ml, and 100 µg/ml, respectively; AF-DP showed anticancer activity against MCF-7 breast cancer cell line. Scanning electron microscopic analysis confirmed the creation of pores and scratches on the surface of the bacterial membrane. The results of this research show that AF-DP can be a candidate for the production of new drugs as an AMP with antimicrobial activity. Communicated by Ramaswamy H. Sarma

Steady and transient rheological properties of four polysaccharides with different chain conformations

AbstractCarbohydrate polymers have broad application prospects, especially in food and cosmetic fields, and rheology is very important for controlling the quality and functions of their final products. Therefore, the steady and transient rheological behaviors of polysaccharides with different chain conformations of triple helix, double helix, and random coils were studied systematically. In our findings, the extraordinary low‐shear thickening phenomena of polysaccharides (lentinan, curdlan, and xanthan) with helix conformation were observed at a certain concentration depending on the stiffness and molecular weight, different from the steady‐shear rheological property of pullulan, which was attributable to the arrangement from order to disorder of stiff chains at the shear rate of < 0.1 s−1. Lentinan, curdlan, and xanthan in solution showed obvious viscoelasticity and thixotropic behavior with significant concentration and stiffness dependence, while the flexible pullulan only exhibited Newtonian viscous fluid even at high concentration of 20%. Stress overshoot for the four polysaccharides occurred after shearing, and the higher stiffness and molecular weight delayed the occurrence of stress overshoot. Obviously, chain conformation plays a key role on controlling the rheology of polysaccharides. This work provides scientific basis for the application of these polysaccharides in food and cosmetics field.

Motion-Induced Noise Detection of Electrode-Pair Towed Antennas Using Helix Coil Sensors

Electrode-pair towed antennas are widely utilized for marine electromagnetic detection, underwater communication, and other purposes. However, the motion-induced noise created by antenna vibrations due to environmental turbulence affects extremely low frequency and super low frequency (ELF/SLF) communications. In this article, we presented a method for detecting the motion-induced noise of electrode-pair towed antennas using helix coil sensors. The equivalent resistance, inductance, capacitance, and conductance (RLCG) transmission model and parameters were derived based on the mirror method of the twisted structure with a shielding layer inside. A water-flow cycling experimental platform was constructed to evaluate two types of antenna sections. Electrode-pair, accelerators, and helix coils sensors signals were sampled and analyzed in time and frequency domain. The comparison results demonstrated that the helix coil sensors achieved a high correlation with the electrode-pair towed antenna in various vibration speeds ranging from 0.7 to 0.9.

Self-Tuning Omnidirectional Wireless Power Transfer Using Double-Toroidal Helix Coils

In this article, we suggest and study a novel omnidirectional wireless power transfer (WPT) system based on unusual double-toroidal helix coils. The suggested antenna is a double-helix coil wounded around a torus. It creates two mutually orthogonal magnetic fields. One is toroidal and confined inside the torus, and another one is poloidal and is distributed outside it. The intensities of these two fields can be independently tuned via the geometry of the turns. The coupling coefficients are tailored to ensure high efficiency regardless of the receiver position and orientation, without active circuitry for tuning or control. This topology provides self-tuning functionality which is achieved when the coupling between the transmitter and receiver is minimized while the coupling in the pairs transmitter–repeater and repeater–receiver is strong. The system consists of three transmitter–repeater pairs orthogonal to each other, ensuring omnidirectional functionality. Experimental results confirm self-tunability and high efficiency for any position and orientation of receivers. The proposed double-helix antenna is applicable to different WPT applications where the coupling/decoupling between coils can be freely controlled.

Sequence analysis and mRNA expression of prolactin receptor gene isoforms in different tissues of sheep during lactation and the post-weaning period.

Few studies on mRNA expression of the prolactin receptor (PRLR) isoforms in different tissues of sheep were reported. The objective of this study was to analyze the gene sequence and mRNA expression of PRLR isoforms in the uterus, mammary gland, ovary, spleen and lymph tissue of ewes during the lactation and post-weaning periods. Ten lactating crossbred ewes (Dorper×Hu sheep) with twin lambs were used in this study. Five ewes were chosen randomly and slaughtered at mid-lactation (35 days after lambing). The remaining five ewes were slaughtered on the 5th day after weaning. Samples of uterus, mammary gland, ovary, spleen and lymph tissue were collected from each ewe to determine the mRNA expression of long PRLR (L-PRLR) and short PRLR (S-PRLR) by RT-qPCR. The physical and chemical properties, the similarity of the nucleotides L-PRLR and S-PRLR genes and the secondary and tertiary structure of the L-PRLR and S-PRLR proteins of sheep were analyzed. The results indicated that the predicted protein molecular weights of L-PRLR and S-PRLR are 65235.36 KD and 33847.48 KD, respectively, with isoelectric points of 5.12 and 8.34, respectively. The secondary protein structures of L-PRLR and S-PRLR are different. For L-PRLR these include alpha helix, extended strand and random coils and β-turns for which the content was 16.01%, 21%, 59.55% and 3.44%, respectively, whereas the secondary protein structures of S-PRLR contain only alpha helices, extended strand and random coils, comprising 18.24%, 30.07% and 48.99%, respectively. The L-PRLR and S-PRLR genes of the sheep (Ovis aries) had nucleotide sequences showing much similarity among ruminants. In these sheep, mRNA expression of L-PRLR and S-PRLR was highest in the uterus and differed between the uterus, ovary, mammary gland, spleen and lymph tissue. The mRNA expression of L-PRLR in lymph tissue was higher during lactation than in the post-weaning period (P < 0.01), whereas mRNA expression of S-PRLR in the uterus and the mammary gland was lower during lactation than during the post-weaning period (P < 0.01). In the uterus, mRNA expression of L-PRLR was higher than that of S-PRLR during lactation (P < 0.01) but there were no significant differences (P < 0.05) for the other five tissues. This study that the L-PRLR and S-PRLR proteins in ewes are mainly composed of extended fragments and random coils. The data also indicate that mRNA expression of L-PRLR and S-PRLR genes varies among different tissues in sheep and is higher in the uterus than in the ovary, spleen, mammary gland and lymph tissue throughout lactation and the post-weaning period.

Purification, biochemical and biophysical characterization of an acidic α-galactosidase from the seeds of Annona squamosa (custard apple)

Alpha galactosidase is an exoglycosidase that cleaves α-D-galactose and has numerous applications in medicine, biotechnology, food and pharma industries. In this study, a low molecular weight acidic α-galactosidase was identified from the seeds of custard apple. The purification of α-galactosidase from the crude extract of defatted seeds was achieved by employing ammonium sulphate fractionation, hydrophobic interaction and gel filtration chromatographic techniques. The purified custard apple α-galactosidase (CaG) migrated as a single band in native PAGE corresponding to molecular weight of ~67 kDa and cleaved chromogenic, fluorogenic and natural substrates. CaG was found to be a heterodimer with subunit masses of 40 and 30 kDa. The kinetic parameters such as KM and Vmax were found to be 0.67 mM and 1.5 U/mg respectively with p-nitrophenyl α-D-galactopyranoside. Galactose, methyl α-D-galactopyranoside and D-galacturonic acid inhibited CaG activity in mixed mode. The CD spectral analysis at far UV region showed that purified CaG exists predominantly as helix (35%), beta sheets (16.3%) and random coils (32.3%) in its secondary structure. These biochemical and biophysical properties of CaG provide leads to understand its primary sequence and glycan structures which will eventually define its novel physiological roles in plants and potential industrial applications.

Bioinformatic Analysis of Catalase Gene Family of &lt;i&gt;Arabidopsis&lt;/i&gt; and Maize

Catalase (CAT) is an antioxidant enzyme, which plays a key role in plant development and abiotic stress response. In this study, three maize&nbsp; ZmCATs&nbsp; and three Arabidopsis&nbsp; AtCATs &nbsp;genes were identified by screening NCBI and phytozome databases. The protein characteristics, evolutionary relationship, gene structure, protein secondary and tertiary structure, gene expression at different developmental stages or under abiotic stress treatment were analyzed. The results showed that there were some similarities between CAT families from the two species. The proteins encoded by ZmCATs and AtCATs genes were hydrophobic. According to phylogenetic tree analysis, CATs gene family was divided into two subfamilies. ZmCATs and AtCATs both contain two conserved domains, and the secondary structures of ZmCATs and AtCATs protein are mainly &alpha;-helix and random coils. The cluster analysis of ZmCATs expression in different growth and development stages showed that &nbsp;ZmCAT1 ,&nbsp; ZmCAT2 &nbsp;and &nbsp;ZmCAT3 &nbsp;were highly expressed in maize growth and development stage. Under abiotic stress, the expression of&nbsp; ZmCATs &nbsp;gene was significantly affected by temperature stress. The results of this study provide a theoretical basis for exploring the function of CAT in maize and other crops.

Identification, localization and expression analysis of beta-carotene isomerase gene family in sugarcane

<p indent=0mm>Strigolactones (SLs), a class of plant hormones, exists widely in plants and involves in the regulation of plant tillering and environmental adaptation. β-carotene isomerase (D27) is a key enzyme for SLs synthesis, but there are few reports about the identification and analysis of <italic>D27</italic> gene family in sugarcane. In this study, five members of <italic>D27</italic> gene family from one of the original parent of modern sugarcane cultivars, <italic>Saccharum spontaneum</italic>, were analyzed. Phylogenetic tree analysis showed that these D27s from <italic>S</italic>.<italic> spontaneum</italic> was clustered into 3 different branches and were highly homologous to sorghum D27s. Conserved domain prediction revealed that D27s contained a typical domain of β-carotene isomerase, Pfam: DUF4033. The results of cis-element analysis showed that<italic> D27s</italic> mainly involved in the regulation of hormone response, plant growth and development, and stress response. Based on the transcriptomic data of the modern cultivated varieties, the expression analysis of the homologous transcripts of <italic>Saccharum spontaneum D27s</italic> showed that <italic>Sspon</italic>.<italic>06G0012830-1A</italic> was regulated at tillering stage and under <italic>Sporisorium scitamineum </italic>infection. Besides, the cDNA sequence of <italic>Sspon</italic>.<italic>06G0012830-1A</italic> was cloned from sugarcane cultivar ROC22 and named as <italic>ScD27</italic>.<italic>1 </italic>(GenBank accession number: MT499895). Bioinformatics analysis indicated that <italic>ScD27</italic>.<italic>1</italic> encoded an unstable protein of 266 amino acids with an isoelectric point of 8.91 and a molecular weight of 30.00 kD, and might be located in the chloroplast, containing chloroplast transit peptides, 4 ubiquitination sites and 18 phosphorylation sites. Its secondary structure mainly included alpha helix and random coils. qRT-PCR analysis demonstrated that <italic>ScD27</italic>.<italic>1</italic> was significantly induced by ABA and H₂O₂ and did not respond to MeJA and SA. Subcellular localization revealed that ScD27.1 might be located in cell membrane and chloroplast and involved in the vesicle sorting or transported by sorting vesicle in plant cells. The results suggested that <italic>ScD27</italic>.<italic>1</italic> may involve in the tillering induced by <italic>S</italic>.<italic> scitamineum </italic>and signaling pathway of ABA and H₂O₂. The present study provides a basic understanding of intracellular transport and tillering in sugarcane and the involvement of <italic>ScD27</italic>.<italic>1 </italic>during sugarcane-<italic>S</italic>.<italic> scitamineum</italic> interaction.

Expression, epitope prediction and IgE‑binding of the &lt;em&gt;Tyrophagus putrescentiae&lt;/em&gt; group 13 allergen

Storage mites, such as Tyrophagus putrescentiae, are an important source of allergens that cause allergic diseases in humans. It has previously been indicated that T. putrescentiae has a high sensitization rate as an allergen in some Asian and European countries. Identifying and cloning the allergens in this species may enable improved diagnostic and therapeutic approaches. The aim of the present study was to clone and sequence the T. putrescentiae group 13 allergen (Tyr p 13) isolated from storage mites in China, to use bioinformatics tools to model its biophysical characteristics and to induce protein expression to test its IgE-binding activity. The full-length cDNA comprised 486 bp and was predicted to include a signal peptide of 22 amino acids. Its secondary structure was shown to comprise an α-helix (10.79%), extended strand (33.81%) and random coils (55.40%). Using homology modeling, the present study constructed a reasonable tertiary structure of Tyr p 13. Linear Bcell epitopes at amino acids 47-53, 70-76, 81-86, 101-105 and 112120 were predicted. Three discontinuous B-cell epitopes were also predicted: i) 47, 48, 49, 50, 51, 52, 53, 70, 71, 72 and 73; ii) 91, 92, 93, 94, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121 and 138; and iii) 74, 76, 79, 81, 82, 83, 84, 86, 101, 102, 103, 104 and 105. SDS-PAGE identified a specific band at the predicted molecular weight of the recombinant Tyr p 13 (rTyr p 13), demonstrating its successful expression. The rTyr p 13 bound to IgE in the serum of 13.2% (5/38) of patients allergic to T. putrescentiae, according to ELISA. The successful cloning of Tyr p 13 and basic bioinformatics analysis of the protein provided a foundation for the further study of this allergen with regards to the diagnosis and treatment of patients allergic to storage mites. These results provided a theoretical basis for the design of rTyr p 13 with modified B-cell epitopes.

Effect of stress on the molecular structure and mechanical properties of supercontracted spider dragline silks.

Supercontraction is one of the most interesting properties of spider dragline silks. In this study, changes in the secondary structures of the Nephila edulis spider dragline silk after it was subjected to different supercontraction processes were investigated by integrating synchrotron Fourier transform infrared (S-FTIR) microspectroscopy and mechanical characterization. The results showed that after free supercontraction, the β-sheet lost most of its orientation, while the helix and random coils were almost totally disordered. Interestingly, by conducting different types of supercontractions (i.e., stretching of the free supercontracted spider dragline silk to its original length or performing constrained supercontraction), it was found that although the molecular structures all changed after supercontraction, the mechanical properties almost remained unchanged when the length of the spider dragline silk did not change significantly. The other interesting conclusion obtained is that the manual stretching of a poorly oriented spider dragline silk cannot selectively improve the orientation degree of the β-sheet in the spider silk, but increase the orientation degree of all conformations (β-sheet, helix, and random). These experimental findings not only help to unveil the structure-property-function relationship of natural spider silks, but also provide a useful guideline for the design of biomimetic spider fiber materials.

Research on the excitation method of symmetrical spiral online detecting sensor of metal debris

By connecting the symmetrical spiral inductive sensor to the oil return pipeline of the lubricating oil, a full flow online detection of the size, quantity and other parameters of the tiny metal debris particles in the lubricating oil solution is realised. Inductive sensors are used to excite symmetrical double helix coils, and alternating electromagnetic fields are generated. Changes in induced electromotive force are detected by the centre induction coil. In order to improve the detection accuracy of tiny metal debris particles, the degree of anti-jamming of the excitation signal, and the transmission distance, a method of stimulating using sinusoidal AC steady current signals was designed. The sinusoidal signal generator is designed based on FPGA, and the sinusoidal AC steady current excitation signal is realised through differential amplification, low-pass filtering, and AC steady current amplification, and experimental verification is performed to achieve better excitation and detection results.

Purification, biochemical and biophysical characterization of a zinc dependent α-mannosidase isoform III from Custard Apple (Annona squamosa) seeds

In the present study, out of three isoforms of α-mannosidase identified in the crude extract of defatted Custard apple seed powder, isoform III has been purified to homogeneity by two-step chromatography: hydrophobic interaction and gel filtration. The purified Custard apple α-mannosidase isoform III (CAM) hydrolyzed both chromogenic (p-nitrophenyl-α-D-mannopyranoside) and fluorescent (4-methylumbelliferyl α-D-mannopyranoside) substrates. Custard apple α-mannosidase migrated as a single band in native PAGE, showed about 220 kDa molecular mass in gel filtration and in SDS PAGE, dissociated into four bands (Mr ~ 75, 68, 56 and 50 kDa respectively). Temperature and pH optima were found to be 50 °C and 4.0–5.0 respectively and CAM was stable up to 60–70 °C. The enzymatic activity of CAM was inhibited by EDTA, Ag+, Hg2+, Ni2+ and swainsonine (IC50 value of 1.5 μM). CAM was observed to be a metallo enzyme requiring zinc for its activity. Kinetic parameters KM and Vmax were found to be 1.75 mM and 0.068 U/mL respectively. The CD spectral analysis at far UV region (190–300 nm) shows that purified CAM exists as helix (30.4%), β turns (18%) and random coils (29.7%) in its secondary structure. Chemical modification studies with N-Bromosuccinimide revealed the presence of tryptophan in its active site.

Mutual inductance calculation for coils with misalignment in wireless power transfer

In wireless power transfer (WPT) systems, the energy transmission channel is established by the coupling relationship between transmitting coil and receiving coil, and the coupling strength is usually measured by coupling coefficient. Therefore, it is necessary to calculate the mutual inductance between transmitting coil and receiving coil when describing their coupling strength. Here, filamentary circular coils and cylindrical helix coils are taken as the object of study, and the formulas for mutual inductance of two coils with misalignment are derived based on Neumann's formula. In addition, the influence of multiple factors, such as axial distance, lateral distance and angle, on mutual inductance is analysed, and the calculated results are verified by experiments. The research results of this paper can be used to estimate the mutual inductance between the couplers in WPT systems, especially when there is misalignment.

Operating characteristics and cooling cost evaluation for HTS receiver arrays of wireless power charging system in superconducting MAGLEV train

Since conventional power supply unit should be attached to HTS magnet in the MAGLEV, a large thermal loss is indispensably caused by power transfer wires and joints, those have been one of essential obstacles in the superconducting MAGLEV train. As the wireless power transfer (WPT) technology based on strongly resonance coupled method realizes large power charging without any wires through the air, there are advantages compared with the wired counterparts, such as convenient, safety and fearless transmission of power during movement. Above all, the WPT technology in the MAGLEV can reduce the cost of tunnel construction since the space of conventional power line doesn’t required. From these merits, the WPT systems have been started to be applied to the wireless charging for various power applications such as transportations (train, underwater ship, electric vehicle). In this study, as a practical approach, authors investigate transfer efficiency and cooling cost for multi-Tx and multi-sized single Tx coils under different size of Rx coils arrays, respectively. Additionally, authors investigated transfer ratio at HTS Rx with helix and spiral Tx coils under different interval. As well as, authors evaluate cooling cost of different sizes of HTS receiver under long single and multi-copper antenna arrays based on nitrogen evaporation method.

In Silico Analysis, Structure Modeling and Phosphorylation Site Prediction of Vitellogenin Protein from Gibelion Catla

Vitellogenin is an egg yolk precursor protein expressed in the females of nearly all oviparous species including fish, amphibians, reptiles, birds, most invertebrates and monotremes .In the present study using bioinformatics tools and in silico modeling and analysis of Vitellogenin protein sequences of Gibelion catla was conducted. Primary structure prediction and physicochemical characterization were performed by computing theoretical isoelectric point (pI) 9.03, molecular weight 144862.03 Da, extinction co-efficient 78325, instability index 42.86 and aliphatic index 113.01. Grand Average of hydropathicity (GRAVY) was computed 0.212. Secondary structure assessment of Vitellogenin protein of carp Gibelion catla using GORIV reveals greater percentage of residues as alpha helix and random coils against the beta sheets. After performing homology modeling using Swiss model, a 3D structure of Vitellogenin of Gibelion catla have been predicted from its amino acid sequence. After the prediction structure has been validated through various validation tools. This homology modeling based structure will provide an insight to its functional aspects and further studies which are based on tertiary structure of protein.

Structure-function analysis of DNA helicase HELQ: A new diagnostic marker in ovarian cancer

It has been previously reported that a deficiency of the helicase, POLQ-like (HELQ) gene increases the risk of ovarian cancer. The present study aimed to explore the structure-function association of HELQ and discuss the effect of molecular structure on the occurrence of tumors. ExPASy tools were employed to analyze the physicochemical properties and secondary structure of the genes. PHYRE2 Protein Fold Recognition Server was used to construct the three-dimensional model and find the ligand-binding sites of HELQ. In addition, the potential functions corresponding to these structures were excavated by comparing and analyzing protein domains. The HELQ protein is located in the cytoplasm (56.5%) and nucleus (21.7%). HELQ has 4 conserved domains, consisting of DEXDc, HELICc, HHH_5 and PRK02362, which contain the adenosine triphosphate (ATP) binding site, nucleotide binding region and putative Mg2+ binding site. In the secondary structure, it was found that HELQ was mainly composed of α helix (46.68%) and random coils (43.05%), with only 10.26% extended strand. According to 3DLigandSite Server, the ligand binding sites appeared in ILE333, LYS335, TYR337, SER362, LEU367, LYS397, GLN340, GLY363, GLY364 and ASN678 of the amino acid sequence. Among the functional protein association networks, regulator of telomere elongation helicase 1, family with sequence similarity 175 member A, small ubiquitin-like modifier 1, DNA polymerase ν and coiled-coil domain containing 158 were involved and co-expressed with HELQ. PredictProtein analysis indicated that the dominant functions of HELQ were ATP-dependent helicase activity and participation in the DNA repair process. Characteristics of the HELQ protein were obtained by bioinformatics analysis, based on which the role of HELQ in DNA replication, DNA repair and maintenance of genomic stability was explored. It was concluded that modulation the function of HELQ helicase may be used in the treatment of ovarian cancer.

Dust mite allergen Der f 4: Expression, characterization, andIgE binding in pediatric asthma.

House dust mite hypersensitivity affects millions of people worldwide, and although many allergens produced by house dust mite species have been identified, some of the less potent allergens remain to be studied. The full-length cDNA encoding the group 4 allergen of the house dust mite species Dermatophagoides farinae (Der f 4) was generated through degenerate primer-based PCR, 5' RACE, and 3' RACE, and the cDNA fragment was cloned into an expression vector for nucleotide sequencing. Following codon optimization and removal of the signal peptide sequence, the mature gene fragment was subcloned into pET-28b (+) and transfected into E.coli BL21 cells for expression. The recombinant protein was purified by nickel affinity chromatography, identified by SDS-PAGE, Western blotting, and MALDI-TOF, and tested by ELISA for IgE reactivity with sera from individuals with asthma. Bioinformatics analyses were used to identify features of Der f 4. SDS-PAGE and Western blotting of the codon-optimized expression product showed a specific band. The mature recombinant Der f 4 was characterized as a stable and hydrophilic 57.9-kDa protein, and its secondary structure comprised alpha helix (25.3%), extended strand (22.51%), and random coils (52.19%). The structure of the recombinant protein was consistent with that of α-amylase. Among 27 pediatric asthma patients, 40.74% exhibited reactivity to rDer f 4 by ELISA. This initial cloning and characterization of the Der f 4 allergen serves as a foundation for future studies into the clinical importance and application of this protein for house dust mite allergy.

Effect of Thermal and High Electric Fields on Secondary Structure of Peanut Protein

This study evaluated the effect of the thermal and high electric field stresses on the secondary structure conformation of peanut protein using Fourier transform infrared spectroscopy. The amide I region between the wavelengths 1700–1600 cm–1 of the spectra were studied for different thermal and high electric field treatments. Within thermal treatments, both hot air roasting and microwave processing treatments were evaluated. Hot air treatments were performed at temperatures of 50, 75, and 100°C from 15, 30, and 45 min while the microwave treatments were conducted at the same temperatures, but for 5, 10, 15, and 20 min. Three experimental conditions were evaluated for the electric field intensity of 10, 15, and 20 kV for 60, 120, and 180 min. Changes were observed at 1654–1650 cm–1, indicating conformational changes in the α-helix secondary structure. Similar changes were observed at various other wavelengths indicating changes in the 3/10 helix, β-sheets and random coils present in the protein. With an increase in the treatment time, the secondary structure reorganizations increased with the creation of new random coils and aggregated strands. Curve-fitting using Gaussian band shapes further supported the observations. In vitro protein digestibility studies were also performed and the protein changes also supported the observations from the spectra.

Styrene-butyl acrylate copolymers latexes prepared with different functional monomers and their application as anti-icing coatings

Four polymer latexes, including Base latex synthesized using styrene and butyl acrylate as the main monomers, Latex Si prepared with 4.0 wt% of vinyl triethoxysilane, Latex F with 4.0 wt% of dodecafluoroheptyl methacrylate and Latex D4 with 8.5 wt% of octamethyl cyclotetrasiloxane (D4), were prepared through a semi-continuous emulsion polymerization. Characterization of the latex films revealed that water absorption of the films of Latex D4 and the Base latex were lower than those of Latexes F and Si; whereas their contact angle with water were also smaller than those of the other two latex films. The latexes were applied as coating onto steel and Al metals of different forms to evaluate their performance in corrosion and anti-icing tests. Coated on steel plates for water resistance test, it was found that Latex D4 and Base latex showed poorer performance; whereas the films made from Latex F and Latex Si showed better performance. In anti-icing tests, with the coating applied either on Al circular helix coils followed by refrigeration after water spray, or on Al stranded power line followed by anti-icing test in an IWT (ice wind tunnel), Latex D4 showed the best anti-icing performance, Base latex with the lowest performance, and the other two, Latex F and Latex Si, located in between. The test in IWT was also conducted with the latexes coated on stainless steel rods used in Al stranded power line with reinforced steel core. The anti-icing effectiveness was quite similar to those observed on Al coils or stranded power transmission lines: Latex D4 showed the highest performance and Base latex the lowest, although the differences of the magnitude in their performance were obviously different in different tests.

Effects of coil shapes on wireless power transfer via magnetic resonance coupling

The wireless system with four coil resonators is a popular configuration for mid-range wireless power transfer (WPT) via magnetic resonance coupling. The design parameters of four coils have strong impact on efficiency, bandwidth, and transfer distance of the WPT system. In this work, a comprehensive study on effects of coil shapes is conducted. In particular, helix coils, planar spiral coils, and square helix coils are studied. It is shown that the helix coils offer the best performance (e.g. the highest efficiency, the widest bandwidth, and the longest transfer distance) under optimal load whereas the planar spiral coils exhibit the worst performance among these three types of coils. Nevertheless, the performance of the WPT system with helix coils degrades more rapidly than these with other two types of coils when the distance between the transmitting and receiving coils increases.