Successful Assembly Research Articles

Assemblability analysis of the modular fixturing systems with accurate grid pattern holes using Monte Carlo simulation

This paper focuses on the assemblability of modular fixturing systems. Two types of stochastic models are proposed: for two holes-two pins (2H2P) and for two holes-two pins-two holes (2H2P2H), both used by modular fixturing systems with multipurpose grid pattern holes. The probability of successful assemblies to engineering specifications is calculated using the Monte Carlo simulation. The weights of the assemblability criterion variables are analysed and several design recommendations are indicated.

A micro-oscillation-driven energy harvester based on a flexible bipolar electret membrane with high output power

This paper reports the successful assembly of a micro-oscillation-driven energy harvester with bipolar electret membrane and dual air gap.

Electrocatalytic and new electrochemical properties of chloropromazine in to silicaNPs/chloropromazine/Nafion nanocomposite: Application to nitrite detection at low potential

In this study, the electrochemical behavior of chloropromazine at glassy carbon (GC) electrode modified with silica nanoparticles/chloropromazine/Nafion (SNPs/CPZ/Nf) nanocomposite was investigated. The apparent electron transfer rate constant (ks), transfer coefficient (α) and surface concentration (Γc) were found to be 0.56s−1, 0.49 and 3.49×10−7molcm2−, respectively. Cyclic voltammetry technique has been used for stabilization of nanocomposite on the surface of GC electrode. Electrochemical impedance spectroscopy (EIS) and transmission electron microscopy (TEM) techniques were used to confirm the successful stepwise assembly procedure of the electrode. The modified electrode showed electrocatalytic activity toward nitrite electro-reduction at 0.12V. The detection limit (signal to noise) and sensitivity are 7μM and 0.0007μA/μM, respectively. The advantages of the nitrite amperometric detector based on the SNPs/CPZ/Nf nanocomposite GCE are a low detection limit, reduction in low potential in particular, high sensitivity and inherent stability at pH2, catalytic activity for nitrite reduction antifouling property toward nitrite and its reduction product. Furthermore, the proposed electrode was used for determination of nitrite in food samples.

A glassy carbon electrode modified with carbon quantum dots and polyalizarin yellow R dyes for enhanced electrocatalytic oxidation and nanomolar detection of l-cysteine

A novel electrochemical sensor for the detection of l-cysteine was proposed based on immobilizing poly (alizarin yellow R)/carbon quantum dots film on glassy carbon electrode. Hydrothermal treatment was used to prepare carbon quantum dots. Transmission electron microscopy and Fourier transform infrared spectroscopy were used for characterization of carbon quantum dots. Electrochemical impedance spectroscopy, cyclic voltammetry and amperommetry were utilized to confirm the successful stepwise assembly procedure of the sensor. The electrocatalytic behaviors of the sensor were also investigated by cyclic voltammetry and amperommetry. Results showed that poly (alizarin yellow R)/carbon dots exhibited a remarkable electrocatalytic activity for the oxidation of l-cysteine under optimal conditions. The electrocatalytic response of the sensor was proportional to the l-cysteine concentration in the range of (0.3 to 3.6μM) and (3.9 to 7.2μM) with a limit of detection and sensitivity of 90nM and 0.482μA/μM, respectively. The modified electrode demonstrated many advantages such as simple preparation, high sensitivity, low detection of limit, excellent catalytic activity at physiological pH values, short response time, and remarkable antifouling property toward l-cysteine and its oxidation product.

Assembly of ultrathin NiOOH nanosheets on electrochemically pretreated glassy carbon electrode for electrocatalytic oxidation of glucose and methanol

The aqueous NiOOH nanosheets were synthesized using a hydrothermal method via a surfactant template under mild reaction conditions. The as-prepared products were characterized by atomic force microscopy (AFM), X-ray diffraction (XRD) and scanning electron microscopy (SEM), the results of which indicated that ultrathin and porous NiOOH nanosheets with a thickness of only several nanometers have been obtained. The obtained NiOOH nanosheets were subsequently assembled on electrochemically pretreated glassy carbon (EPGC) electrode through a simple physical bath deposition method to form NiOOH/EPGC electrode. SEM, energy dispersive X-ray spectroscopy (EDX) and electrochemical impedance spectroscopy (EIS) proved the successful assembly of NiOOH on EPGC surface. The effective deposition of NiOOH electrocatalyst on electrode is believed to result from the higher surface area and higher surface concentration of CO functional groups existing on EPGC surface. Glucose and methanol were selected as model molecules to investigate the electrocatalytic performance of NiOOH/EPGC electrode. The electrochemical experiments revealed that a favorable activity of the NiOOH/EPGC electrode toward electrooxidation of glucose and methanol has been found. The present NiOOH/EPGC based amperometric sensor exhibited a rapid and highly sensitive response to glucose and methanol, which might find promising applications in medical applications, biological fuel cells and food industries.

Chaperone-Assisted Formation of Cucurbit[8]uril-Based Molecular Porous Materials with One-Dimensional Channel Structure.

Exploiting "chaperone molecule" to navigate the successful assembly energy landscapes has been extensively used in biological systems, whereas in artifical supramolecular systems the "chaperone-assisted" assembly strategy to be used for the synthesis of materials with novel structures or the structures to be hardly prepared by "conventional" methods are still far from realizing the potential functions. In this work, we present a new example of small organic molecule acting as "chaperone molecule" in the facile formation of organic molecular porous materials. This porous material is composed of pure cucurbit[8]uril (CB[8]) macrocycle and possesses a honeycomb-like structure with an isolated and relatively large one-dimensional (1D) nanochannel. Moreover, it has good chemical and thermal stability, and shows a good adsorption capability for large molecule loading. Importantly, with the assistance of chaperone molecules, pure CB[8] could also be recycled even from a complex aqueous solution, demonstrating a powerful purification method of CB[8] from complex systems.

Phylogenetics and biogeography of the dung beetle genus Onthophagus inferred from mitochondrial genomes

Phylogenetic relationships of dung beetles in the tribe Onthophagini, including the species-rich, cosmopolitan genus Onthophagus, were inferred using whole mitochondrial genomes. Data were generated by shotgun sequencing of mixed genomic DNA from >100 individuals on 50% of an Illumina MiSeq flow cell. Genome assembly of the mixed reads produced contigs of 74 (nearly) complete mitogenomes. The final dataset included representatives of Onthophagus from all biogeographic regions, closely related genera of Onthophagini, and the related tribes Onitini and Oniticellini. The analysis defined four major clades of Onthophagini, which was paraphyletic for Oniticellini, with Onitini as sister group to all others. Several (sub)genera considered as members of Onthophagus in the older literature formed separate deep lineages. All New World species of Onthophagus formed a monophyletic group, and the Australian taxa are confined to a single or two closely related clades, one of which forms the sister group of the New World species. Dating the tree by constraining the basal splits with existing calibrations of Scarabaeoidea suggests an origin of Onthophagini sensu lato in the Eocene and a rapid spread from an African ancestral stock into the Oriental region, and secondarily to Australia and the Americas at about 20–24 Mya. The successful assembly of mitogenomes and the well-supported tree obtained from these sequences demonstrates the power of shotgun sequencing from total genomic DNA of species pools as an efficient tool in genus-level phylogenetics.

Quality assured tightening of screw joints

Assembly of critical threaded connections such as safety belt and steering wheel screw joints must be quality assured to 100%. Not only the screw needs to be in position but the strength of the joint must also be guaranteed. To accomplish this, classical process surveillance is combined with angle monitoring and screws with special features. A plant system that keeps track on cars of various variants sends information to a screw joint controller that in turn sends a unique parameter set to the screw joint equipment. Together with so-called socket trays and balancing rules, the process arrangement can be made in such a way that the wrong screw can never be assembled without detection. To provide sufficient strength of joints, different kinds of angle monitoring are used. For example, entering/down running angle monitoring that are used to secure sufficient thread engagement with static high strength joints. Angle monitoring is also used to control that all parts are in position before the joint is tightened. For clamp load critical joints, final angle monitoring is used. Together with standard torques and standard assembly friction given by standard fasteners, sufficient clamping force can be guaranteed. With clamp load critical chassis joints, gradient-controlled yield point tightening has shown to be a successful assembly technique with the all new Volvo XC90. Furthermore, screws with special thread geometries are used to avoid cross threading, and in many cases hand entering can be taken away. Altogether, it can be concluded that the Volvo Cars assembly technology not only is very safe but also at a relatively low cost.

Tubulins interact with porcine and human S proteins of the genus Alphacoronavirus and support successful assembly and release of infectious viral particles

Coronavirus spike proteins mediate host-cell-attachment and virus entry. Virus replication takes place within the host cell cytosol, whereas assembly and budding occur at the endoplasmic reticulum-Golgi intermediate compartment. In this study we demonstrated that the last 39 amino acid stretches of Alphacoronavirus spike cytoplasmic domains of the human coronavirus 229E, NL63, and the porcine transmissible gastroenteritis virus TGEV interact with tubulin alpha and beta chains. In addition, a partial co-localization of TGEV spike proteins with authentic host cell β-tubulin was observed. Furthermore, drug-induced microtubule depolymerization led to changes in spike protein distribution, a reduction in the release of infectious virus particles and less amount of spike protein incorporated into virions. These data demonstrate that interaction of Alphacoronavirus spike proteins with tubulin supports S protein transport and incorporation into virus particles.

Gap-Dependent Coupling of Ag–Au Nanoparticle Heterodimers Using DNA Origami-Based Self-Assembly

We fabricate heterocomponent dimers built from a single 40 nm gold and a single 40 nm silver nanoparticle separated by sub-5 nm gaps. Successful assembly mediated by a specialized DNA origami platform is verified by scanning electron microscopy and energy-dispersive X-ray characterization. Dark-field optical scattering on individual dimers is consistent with computational simulations. Direct plasmonic coupling between each nanoparticle is observed in both experiment and theory only for these small gap sizes, as it requires the silver dipolar mode energy to drop below the energy of the gold interband transitions. A new interparticle-spacing-dependent coupling model for heterodimers is thus required. Such Janus-like nanoparticle constructs available from DNA-mediated assembly provide an effective tool for controlling symmetry breaking in collective plasmon modes.

Fabrication and characterization of a nanostructured TiO2/In2S3-Sb2S3/CuSCN extremely thin absorber (eta) solar cell

In this work we report the successful assembly and characterization of a TiO2/In2S3-Sb2S3/CuSCN extremely thin absorber solar cell. Nanostructured TiO2 deposited by screen printing on an ITO substrate was used as an n-type electrode. An ∼80 nm extremely thin layer of the system In2S3-Sb2S3 deposited by successive ionic layer adsorption and a reaction (silar) method was used as an absorber. The voids were filled with p-type CuSCN and the entire assembly was completed with a gold contact. The solar cell fabricated with this heterostructure showed an energy conversion efficiency of 4.9%, which is a promising result in the development of low cost and simple fabrication of solar cells.

Computational support for a scaffolding mechanism of centriole assembly.

Centrioles are essential for forming cilia, flagella and centrosomes. Successful centriole assembly requires proteins of the SAS-6 family, which can form oligomeric ring structures with ninefold symmetry in vitro. While important progress has been made in understanding SAS-6 protein biophysics, the mechanisms enabling ring formation in vivo remain elusive. Likewise, the mechanisms by which a nascent centriole forms near-orthogonal to an existing one are not known. Here, we investigate possible mechanisms of centriole assembly using coarse-grained Brownian dynamics computer simulations in combination with a rate equation approach. Our results suggest that without any external factors, strong stabilization associated with ring closure would be needed to enable efficient ring formation. Strikingly, our simulations reveal that a scaffold-assisted assembly mechanism can trigger robust ring formation owing to local cooperativity, and that this mechanism can also impart orthogonalilty to centriole assembly. Overall, our findings provide novel insights into the organizing principles governing the assembly of this important organelle.

Characterization of virus-like particles derived from a GII.3 norovirus strain distantly related with current dominating strains.

Genogroup II, genotype 3 noroviruses (GII.3 NoVs) are secondary to GII.4 NoVs in causing acute non-bacterial gastroenteritis worldwide. In our previous study, we found that virus-like particles (VLPs) derived from a GII.3 NoV strain exhibited no binding activity to any salivary and synthetic histo-blood group antigens (HBGAs) tested. In this study, the nucleotide sequence encoding the major capsid protein of another documented GII.3 NoV strain was codon-optimized and synthesized, and the major capsid protein was expressed using recombinant baculovirus virus expression system. The assembly of VLPs was verified by electron microscopy, and the binding profiles of the assembled VLPs to salivary HBGAs were determined, and in vitro VLP-salivary HBGAs binding blockade assay was used to test the cross-blocking effects of hyperimmune sera produced against different genotypes (GI.2, GII.3, and GII.4). The expression of the major capsid proteins led to the successful assembly of VLPs, and in vitro VLP-salivary HBGAs binding assay indicated that the assembled VLPs bound to salivary HBGAs from blood type A, B, AB, and O individuals, with the highest binding capacity to type A salivary HBGAs. In vitro VLP-salivary HBGAs binding blockade assay demonstrated the absence of blocking activities for hyperimmune sera produced against GI.2and GII.4 VLPs and the presence of blocking activity for that against GII.3 VLPs. Our results suggest the absence of cross-blocking activities among different genotypes and the presence of blocking activities between GII.3 NoVs from different clusters, which might have implications for the design of multivalent NoV vaccines.

Efficient Cementing of CH3NH3PbBr3 Nanoparticles to Upconversion Nanoparticles Visualized by Confocal Microscopy

Upconversion‐perovskite nanohybrids are prepared by assembling CH3NH3PbBr3 perovskite nanoparticles (PK) with naked NaYF4:Yb3+,Tm3+ nanoparticles (UCn) via an innovative strategy consisting of using cucurbit[7]uril (CB[7]) to anchor the perovskite nanoparticles firmly and closely to the upconversion nanoparticles, thus leading to UCn@PKCB nanohybrids. A commercial multiphoton laser scanning confocal microscope is used to demonstrate the successful assembly. This technique proves to be useful to evaluate luminescence lifetime in the range of several tens of μs and allows visualization of the extraordinarily efficient nontrivial resonance energy transfer from the upconversion nanoparticle to the perovskite after near‐infrared (NIR) excitation of the nanohybrid as well as the homogeneity of the UCn@PKCB sample. The considerable photostability of the perovskite in these nanohybrids is demonstrated by prolonged irradiation of the nanohybrid under UV light as well as under NIR light.

Allosteric Control of Icosahedral Capsid Assembly.

During the life cycle of a virus, viral proteins and other components self-assemble to form an ordered protein shell called a capsid. This assembly process is subject to multiple competing constraints, including the need to form a thermostable shell while avoiding kinetic traps. It has been proposed that viral assembly satisfies these constraints through allosteric regulation, including the interconversion of capsid proteins among conformations with different propensities for assembly. In this article, we use computational and theoretical modeling to explore how such allostery affects the assembly of icosahedral shells. We simulate assembly under a wide range of protein concentrations, protein binding affinities, and two different mechanisms of allosteric control. We find that above a threshold strength of allosteric control, assembly becomes robust over a broad range of subunit binding affinities and concentrations, allowing the formation of highly thermostable capsids. Our results suggest that allostery can significantly shift the range of protein binding affinities that lead to successful assembly and thus should be taken into account in models that are used to estimate interaction parameters from experimental data.

Immunogenicity of Leishmania-derived hepatitis B small surface antigen particles exposing highly conserved E2 epitope of hepatitis C virus.

BackgroundHepatitis C virus (HCV) infection is a major health problem worldwide, affecting an estimated 2–3 % of human population. An HCV vaccine, however, remains unavailable. High viral diversity poses a challenge in developing a vaccine capable of eliciting a broad neutralizing antibody response against all HCV genotypes. The small surface antigen (sHBsAg) of hepatitis B virus (HBV) has the ability to form highly immunogenic subviral particles which are currently used as an efficient anti-HBV vaccine. It also represents an attractive antigen carrier for the delivery of foreign sequences. In the present study, we propose a bivalent vaccine candidate based on novel chimeric particles in which highly conserved epitope of HCV E2 glycoprotein (residues 412–425) was inserted into the hydrophilic loop of sHBsAg.ResultsThe expression of chimeric protein was performed in an unconventional, Leishmania tarentolae expression system resulting in an assembly of particles which retained immunogenicity of both HCV epitope and sHBsAg protein. Direct transmission electron microscopy observation and immunogold staining confirmed the formation of spherical particles approximately 22 nm in diameter, and proper foreign epitope exposition. Furthermore, the sera of mice immunized with chimeric particles proved reactive not only to purified yeast-derived sHBsAg proteins but also HCV E2 412–425 synthetic peptide. Most importantly, they were also able to cross-react with E1E2 complexes from different HCV genotypes.ConclusionsFor the first time, we confirmed successful assembly of chimeric sHBsAg virus-like particles (VLPs) in the L. tarentolae expression system which has the potential to produce high-yields of properly N-glycosylated mammalian proteins. We also proved that chimeric Leishmania-derived VLPs are highly immunogenic and able to elicit cross-reactive antibody response against HCV. This approach may prove useful in the development of a bivalent prophylactic vaccine against HBV and HCV and opens up a new and low-cost opportunity for the production of chimeric sHBsAg VLPs requiring N-glycosylation process for their proper functionality and immunogenicity.

Effect of pH on the structure and drug release profiles of layer-by-layer assembled films containing polyelectrolyte, micelles, and graphene oxide.

Layer by layer (lbl) assembled multilayer thin films are used in drug delivery systems with attractive advantages such as unlimited selection of building blocks and free modification of the film structure. In this paper, we report the fundamental properties of lbl films constructed from different substances such as PS-b-PAA amphiphilic block copolymer micelles (BCM) as nano-sized drug vehicles, 2D-shaped graphene oxide (GO), and branched polyethylenimine (bPEI). These films were fabricated by successive lbl assembly as a result of electrostatic interactions between the carboxyl group of BCM and amine group of functionalized GO or bPEI under various pH conditions. We also compared the thickness, roughness, morphology and degree of adsorption of the (bPEI/BCM) films to those in the (GO/BCM) films. The results showed significant difference because of the distinct pH dependence of each material. In addition, drug release rates of the GO/BCM film were more rapid those of the (bPEI/BCM) film in pH 7.4 and pH 2 PBS buffer solutions. In (bPEI/BCM/GO/BCM) film, the inserted GO layers into bPEI/BCM multilayer induced rapid drug release. We believe that these materials & pH dependent film properties allow developments in the control of coating techniques for biological and biomedical applications.

Controllable formation of high density SERS-active silver nanoprism layers on hybrid silica-APTES coatings

In this work sol-gel process for preparation of the uniform hybrid silica-3-aminopropyltriethoxysilane (APTES) coatings on glass surface is presented from mechanistic point of view. The suggested synthetic approach is straightforward, scalable and provides the means to tune the amount of amino groups on the surface simply by changing concentration of APTES in the initial sol. Deposition rate of different size silver nanoprisms (AgNPRs) on hybrid silica coatings of various amounts of APTES were studied and their performance as SERS materials were probed. The acquired data shows that the deposition rate of AgNPRs can be tuned by changing the amount of APTES. The optimal amount of APTES was found to be crucial for successful AgNPRs assembly and subsequent uniformity of the final SERS substrate—too high APTES content may result in rapid non-stable aggregation and non-uniform assembly process. SERS study revealed that SERS enhancement is the strongest at moderate AgNPRs aggregation level whereas it significantly drops at high aggregation levels.

Use of microalgae Chlamydomonas reinhardtii for production of double-stranded RNA against shrimp virus

RNA interference has been proposed to be a promising tool for combating shrimp viruses. Antiviral double-stranded (ds)RNA has been mostly produced in Escherichia coli-expression system because of its high efficiency and inexpensive operations. However, overusing the bacteria may raise concerns regarding public health and environmental contamination, and seeking for a new dsRNA production platform would be alternative for future molecular farming. In this study, we exploited the green microalgae Chlamydomonas reinhardtii to produce dsRNA targeting the lethal shrimp yellow head virus (YHV). The expression plasmid pSL18 for C. reinhardtii was constructed to contain YHV-specific hairpin RNA expression cassette, and the successful assembly of pSL18-YHV was confirmed by PCR and enzymatic digestions. Glass bead method was employed for transformation of C. reinhardtii nuclear genome with pSL18-YHV. Microalgal expression of dsRNA-YHV, approximately 45ng from 100-mL culture, was detected by qRT-PCR. Oral feeding experiment on postlarval shrimp revealed that the formulated feed with C. reinhardtii expressing dsRNA-YHV, at the ratio of 1×108 transformants per gram feed, improved 22% survival rate after YHV challenge. The present study suggests that C. reinhardtii can be bioengineered to produce viral-specific dsRNA for shrimp viral disease control, and the developed qRT-PCR could detect microalgal dsRNA with detection limit of subpicogram.

Water in Oil Emulsions: A New System for Assembling Water-soluble Chlorophyll-binding Proteins with Hydrophobic Pigments.

Chlorophylls (Chls) and bacteriochlorophylls (BChls) are the primary cofactors that carry out photosynthetic light harvesting and electron transport. Their functionality critically depends on their specific organization within large and elaborate multisubunit transmembrane protein complexes. In order to understand at the molecular level how these complexes facilitate solar energy conversion, it is essential to understand protein-pigment, and pigment-pigment interactions, and their effect on excited dynamics. One way of gaining such understanding is by constructing and studying complexes of Chls with simple water-soluble recombinant proteins. However, incorporating the lipophilic Chls and BChls into water-soluble proteins is difficult. Moreover, there is no general method, which could be used for assembly of water-soluble proteins with hydrophobic pigments. Here, we demonstrate a simple and high throughput system based on water-in-oil emulsions, which enables assembly of water-soluble proteins with hydrophobic Chls. The new method was validated by assembling recombinant versions of the water-soluble chlorophyll binding protein of Brassicaceae plants (WSCP) with Chl a. We demonstrate the successful assembly of Chl a using crude lysates of WSCP expressing E. coli cell, which may be used for developing a genetic screen system for novel water-soluble Chl-binding proteins, and for studies of Chl-protein interactions and assembly processes.