Assembly Interface Research Articles

Multi-chip module integration of Hybrid Silicon CMOS and GaN Technologies for RF Transceivers

Digital transceiver architectures offer the potential for achieving wireless hardware flexibility to frequency and modulation scheme for future-generation communications systems. Additionally, digital transmitters lend themselves to the use of switch-mode power amplifiers, which can have significantly higher efficiency than their linear counterparts. Two proposed architectures for realizing digital transmitters will be described in this work, both of which employ a hybrid combination of silicon integrated circuits (IC) and a power technology (e.g. GaN). This hybrid architecture takes advantage of the silicon to implement the high-complexity signal processing required for wireless communications, and uses power devices with high power density and low parasitic capacitance to sufficiently amplify the RF signals for transmission. Unfortunately, interfacing the low-power RF switching signals with off-chip high-power devices poses numerous design challenges, including: generation of integrated silicon power drivers with sufficient voltage swing for controlling power devices such as GaN, mitigation of on-chip current transients, wideband assembly interface from the silicon IC to the power device, and full system design verification using multiple process technologies. This work presents two CMOS driver architectures that can be used to interface low-power CMOS processing circuits with off-chip high-power devices. This work also details the performance limitations when assembling and interfacing multiple process technologies that are not co-located on the same IC. The main function of the driver circuitry within the digital transceiver system is to interface the low-power digital modulator to a large, high capacitance, off-chip power device. The driver must provide adequate transient current to charge/discharge the off-chip power devices' input capacitance through parasitic routing. Furthermore, the driver is designed to exhibit rise/fall times of less than 5% of the switching period and low jitter to meet RF signal quality requirements. Since silicon process technologies typically have much lower voltage breakdowns than those required to drive a power devie (e.g. GaN device), special driver architectures must be implemented to ensure the CMOS devices never exceed their breakdown voltages. Two architectures were implemented within this work to simultaneously achieve RF switching speeds and 5V signal swing from a 0.9V silicon CMOS process technology. The two architectures are: 1) a House-of-Cards configuration, and 2) a Cascode topology. These architectures will be detailed and compared with respect to performance in this presentation. Two of the most common techniques to assemble and connect a silicon IC, which includes the driver circuitry, and a (GaN) power device are: 1) direct wire bonding or flip-chip connection from the IC to the GaN, and 2) connection through a board or package interface circuit. Since most high-performance RF power devices such as GaN have negative threshold voltage, the driver (CMOS) IC must either: 1) have a supply and ground that are shifted to negative voltage values, or 2) decouple the IC's output from the GaN device's input in order to properly control the GaN. Off-chip decoupling is more easily implemented, but may limit maximum operating frequencies due to the added interface network and board/module parasitics. This work shall detail the interface models and compare the assembly procedures and potential performance limits when using both of these most common assembly techniques.

Molecular architecture and regulation of BCL10-MALT1 filaments

The CARD11-BCL10-MALT1 (CBM) complex triggers the adaptive immune response in lymphocytes and lymphoma cells. CARD11/CARMA1 acts as a molecular seed inducing BCL10 filaments, but the integration of MALT1 and the assembly of a functional CBM complex has remained elusive. Using cryo-EM we solved the helical structure of the BCL10-MALT1 filament. The structural model of the filament core solved at 4.9 Å resolution identified the interface between the N-terminal MALT1 DD and the BCL10 caspase recruitment domain. The C-terminal MALT1 Ig and paracaspase domains protrude from this core to orchestrate binding of mediators and substrates at the filament periphery. Mutagenesis studies support the importance of the identified BCL10-MALT1 interface for CBM complex assembly, MALT1 protease activation and NF-κB signaling in Jurkat and primary CD4 T-cells. Collectively, we present a model for the assembly and architecture of the CBM signaling complex and how it functions as a signaling hub in T-lymphocytes.

3D printed Lego®-like modular microfluidic devices based on capillary driving

The field of how to rapidly assemble microfluidics with modular components continuously attracts researchers’ attention, however, extra efforts must be devoted to solving the problems of leaking and aligning between individual modules. This paper presents a novel type of modular microfluidic device, driven by capillary force. There is no necessity for a strict seal or special alignment, and its open structures make it easy to integrate various stents and reactants. The key rationale for this method is to print different functional modules with a low-cost three-dimensional (3D) printer, then fill the channels with capillary materials and assemble them with plugs like Lego® bricks. This rapidly reconstructed modular microfluidic device consists of a variety of common functional modules and other personalized modules, each module having a unified standard interface for easy assembly. As it can be printed by a desktop 3D printer, the manufacturing process is simple and efficient, with controllable regulation of the flow channel scale. Through diverse combinations of different modules, a variety of different functions can be achieved, without duplicating the manufacturing process. A single module can also be taken out for testing and analysis. What’s more, combined with basic circuit components, it can serve as a low-cost Lego®-like modular microfluidic circuits. As a proof of concept, the modular microfluidic device has been successfully demonstrated and used for stent degradation and cell cultures, revealing the potential use of this method in both chemical and biological research.

Molecular determinants of Ca2+ sensitivity at the intersubunit interface of the BK channel gating ring

The large-conductance calcium-activated K+ (BK) channel contains two intracellular tandem Ca2+-sensing RCK domains (RCK1 and RCK2), which tetramerize into a Ca2+ gating ring that regulates channel opening by conformational expansion in response to Ca2+ binding. Interestingly, the gating ring’s intersubunit assembly interface harbors the RCK2 Ca2+-binding site, known as the Ca2+ bowl. The gating ring’s assembly interface is made in part by intersubunit coordination of a Ca2+ ion between the Ca2+ bowl and an RCK1 Asn residue, N449, and by apparent intersubunit electrostatic interactions between E955 in RCK2 and R786 and R790 in the RCK2 of the adjacent subunit. To understand the role of the intersubunit assembly interface in Ca2+ gating, we performed mutational analyses of these putative interacting residues in human BK channels. We found that N449, despite its role in Ca2+ coordination, does not set the channel’s Ca2+ sensitivity, whereas E955 is a determinant of Ca2+ sensitivity, likely through intersubunit electrostatic interactions. Our findings provide evidence that the intersubunit assembly interface contains molecular determinants of Ca2+-sensitivity in BK channels.

Multi-criteria retrieval of CAD assembly models

Abstract Being able to reuse existing design knowledge is of major interest to help designers during the creation of new products. This is true at the level of the parts and even more at the level of the assemblies of multiple parts. Meaningful information and knowledge can be extracted from existing geometric models and associated data and metadata, as well as from the processes followed to define them. This paper proposes a method to characterize and structure CAD assembly models to enable the retrieving of similar models from a database. A framework has been devised for the retrieval of globally and/or partially similar assembly models according to multiple user-specified search criteria. It is based on an assembly descriptor, called the Enriched Assembly Model, which is an attributed graph that encodes all the required data automatically extracted from the geometry and structure of the CAD models. The data are organized in four layers: structural, assembly interface, shape and statistic layers. Starting from a real CAD model or from an abstract query model, the algorithm retrieves models from the database by solving a matching problem. The matching between two assembly models is translated into the problem of finding a sub-isomorphism between two EAMs. The layered organization of the EAM allows partially defined queries, which can be further refined. The effectiveness of the proposed approach is illustrated with results obtained from the developed software prototype. Highlights Retrieval of CAD assembly models global or partial similar to a given one. An Enriched Assembly Model is created from the B-rep of each model to compare. Definition of different criteria of similarities to fit user requests. Creation of an association graph from the two Enriched Assembly Models to compare. Model matching is achieved by identifying the maximum clique in the association graph.

Effect of Bond Layer Properties to Thermo-Mechanical Stresses in Flip Chip Packaging

The flip chip bonding technology is widely used in electronic packaging as a result of improvements towards mechanical performance of layered structures. However, thermal mismatch shear and peeling stress are often induced by the differences of the material properties and geometries of bond layer during the high temperature change at operating stage. Intrinsically, these thermo-mechanical stresses play a very significant role in the design and reliability of the flip chip package. Therefore, this project aims to develop a methodology to find optimized bonding material thermo-mechanical properties and geometries in relation to the packaging layers in order to eliminate or reduce thermal mismatch stresses that occur in multi-layered structures in electronic packaging. The closed-form solution of thermo-mechanical analysis of bi-material assembly with bond layer is provided. Parametric study will be carried out in order to study the influence of bond layer parameters on interfacial thermal stresses of a flip chip assembly. These parameters include Young modulus, Coefficient of Thermal Expansion (CTE), Poisson’s ratio and thickness of the bond layer. It is found that the shearing stresses and peeling stresses decreased considerably at the interface with the increase of bond layer Young Modulus and thickness. On the other side, bond layer CTE and Poisson ratio show almost no significant effect on the interfacial shearing stress and peeling stress along the interface in a bi-material assembly.

Long-term Results of Implant Related Complications after Lumbar Fusion Using a Non-rigid Transpedicular Pedicle Screw-Rod System

Introduction Transpedicular fixation is associated with the risk of hardware failure, such as screw/rod breakage and/or loosening at the screw-rod interface and difficulties in the system assembly, which remains a significant clinical problem. Removal or revision of the spinal implants is often required. This is a retrospective radiological study of the single- and two-level lumbar stabilization procedures (TLIF, PLIF or PLF) performed from January 2002 to December 2012 using a non-rigid transpedicular implant system. The purpose of this study was to retrospectively analyze the radiological outcome of 1280 patients focusing on implant related complications. Material and Methods 1280 patients were included into the study. The female/male ratio was 56%/44%, the mean age was 59 years (18–88), the mean FU time was 32 months. Indications for surgery were DDD, FBS and spondylolisthesis (DDD: 77%, FBS: 18%, spondylolisthesis: 5%). There were 727 single-level stabilizations and 553 two-level stabilizations in this cohort. The radiological status of the implants was assessed on lateral and AP X-rays and available CT scans by independent radiologists. We investigated the occurence of screw breakage, screw loosening and element rod breakage, rod slipping and movement. Results In the single-level group 8 screw breakage (1.1%), 27 screw loosening (3.7%), 9 element rod breakage (1.2%) and 47 element rod slippage or movement (6.5%) were detected. In the two-level group 9 screw breakage (1.6%), 30 screw loosening (5.4%), 14 element rod breakage (2.5%) and 37 element rod slippage or movement (6.7%) were present. Conclusion Comparing the result of this retrospective radiological study with the available literature data, we can state that the rate of implant related failures in case of the nonrigid transpedicular system is lower than in the previously published studies. Low implant complicationn rate can be associated with the effect of the non-rigid stabilization on bony remodelling at the surroundings of the transpedicular screws. The influence of non-union rate and sagittal alignment on the outcome needs further evaluations.

Towards Establishing Similar Assembly Interfaces for a Mixed-product Assembly System

Developing a mixed-product assembly line (MPAL) is an elaborate task due to the complexity raised by product variety. This paper proposes that securing similar assembly interfaces across distinct product families is an essential requirement of MPALs which facilitates flexibility and reduces complexity. The concept of similar assembly interfaces has been developed and analysed in a case study at a heavy vehicle manufacturing company. The results suggest that assembly interfaces can be defined according to generic assembly operation steps: pick, place and attach. The paper highlights the need for development of a cross-functional methodology to analyse and establish similar assembly interfaces.

Biomimetic interfaces to trigger tissue restoration

Event Abstract Back to Event Biomimetic interfaces to trigger tissue restoration Ennio Tasciotti1, Francesca Taraballi1, Alessandro Parodi1, Jonathan O. Martinez1, Silvia Minardi1, Naama E. Toledano Furman1, Roberto Molinaro1, Fernando Cabrera1, Laura Pandolfi1, Bruna Corradetti1, Ciro Chiappini1, Jeffrey Van Eps1, Anna Tampieri1 and Bradley K. Weiner1 1 Houston Methodist Research Institute, Regenerative Medicine, United States Introduction: Cells interact and locally interface with the surrounding environment at the macroscale (whole organ), microscale (tissue), and nanoscale (extracellular matrix). Advances in micro and nano-engineering allow the synthesis of materials with features that allow to control and direct cell behavior at multiple scales. By tuning the physical, chemical and biological properties of the materials to match those of native tissues and of cellular processes, we generated biomimetic platforms able to overcome the biological barriers involved in drug delivery and tissue repair. By using the design principles of biomimicry, we exploited the nano-bio interface as a way to negotiate the restoration of tissues function. Materials and Methods: We developed two main classes of biomimetic materials: implantables and injectables. In both cases we applied fabrication strategies based on use of biomaterials able to mimic the material-cell interface for composition, architecture, function, assembly, and biochemical environment. In fact, in the synthesis of our multi-functional platforms was performed using exclusively the components typically found in the body: cellular membranes, proteins, or natural extracellular components (minerals and sugars). Results and Discussion: To overcome the barriers encountered during systemic administration, we developed a drug delivery system comprised of purified leukocyte membranes grafted onto the surface of a biodegradable core (i.e., leuko-like vectors, LLV). The proteolipid material transferred to LLV functioned as a biomimetic camouflage that allowed the inhibition of opsonization and reticulo-endothelial internalization; promoted the increased adherence to inflamed vasculature (Fig 1A), and the activation of intracellular pathways that resulted in the avoidance of endolysosomal entrapment and an increase in vascular permeability (Fig 1B)[1]. To gain access to the cytosol and increase the delivery of biologically labile payloads (nucleic acids), we developed biodegradable nanoneedles capable of directing interfacing with the cytosol through the penetration of the cellular membrane (i.e., nanoinjection). This nano-bio interface did not induce any toxic response in the cell by prompting the rearrangement of the nuclear and plasma membrane (Fig 1C,D)[2],[3], and allowed the in vivo delivery of genes to locally trigger increased neovascularization2 (Fig 1E-G). In tissue regeneration we widely exploited the idea of actively targeting the stem cell niche using different routes. We mimicked the regenerative niche in pore size, stiffness and overall architecture (Fig 2 A, B, C)[4]. Using nanoengineering, we tuned the release profiles of the embedded growth factors to control their local concentration to resemble the kinetics observed in physiological conditions (Fig 2 D, E, F, H)[5],[6]. All these strategies were successfully applied to functionally regenerate both hard and soft tissues. Conclusion: Biomimetic nanomaterials represent a powerful solution to interact with cells and guide their ultimate fate. By engineering surfaces to bestow them with the ability to instruct cells towards a regenerative outcome we achieved superior functional recovery and therapeutic outcome through the activation of the natural processes of cell and tissue healing.

MTConnect Enabled Interoperable Monitoring System for Finish Machining Assembly Interfaces of Large-scale Components

Monitoring is an important issue for finish machining the assembly interface of the large-scale component, as it plays a crucial role in ensuring security and reliability in the finish machining system. To overcome the interoperable problems caused by different proprietary interfaces and communication protocols, this paper proposes an MTConnect compliant monitoring system for acquisition and supervision of the pivotal data during the finish machining process. The framework of the finish machining system is introduced at first, in which the main components and the workflow are described. What is more, the vital procedure and the involved process data are pointed out. Then the MTConnect standard is used to model the finish machining system, including the architecture and the data items. Based on the presented MTConnect model, a web-based monitoring system is developed for data collection and monitoring while machining the assembly interface of the large-scale component. The validity and the interoperability of the proposed approach are verified by collection and monitoring of the process data during finish machining the assembly interface of a vertical tail.

KSHV but not MHV-68 LANA induces a strong bend upon binding to terminal repeat viral DNA.

Latency-associated nuclear antigen (LANA) is central to episomal tethering, replication and transcriptional regulation of γ2-herpesviruses. LANA binds cooperatively to the terminal repeat (TR) region of the viral episome via adjacent LANA binding sites (LBS), but the molecular mechanism by which LANA assembles on the TR remains elusive. We show that KSHV LANA and MHV-68 LANA proteins bind LBS DNA using strikingly different modes. Solution structure of LANA complexes revealed that while kLANA tetramer is intrinsically bent both in the free and bound state to LBS1–2 DNA, mLANA oligomers instead adopt a rigid linear conformation. In addition, we report a novel non-ring kLANA structure that displays more flexibility at its assembly interface than previously demonstrated. We identified a hydrophobic pivot point located at the dimer–dimer assembly interface, which gives rotational freedom for kLANA to adopt variable conformations to accommodate both LBS1–2 and LBS2–1–3 DNA. Alterations in the arrangement of LBS within TR or at the tetramer assembly interface have a drastic effect on the ability of kLANA binding. We also show kLANA and mLANA DNA binding functions can be reciprocated. Although KSHV and MHV-68 are closely related, the findings provide new insights into how the structure, oligomerization, and DNA binding of LANA have evolved differently to assemble on the TR DNA.

Molecular basis of death effector domain chain assembly and its role in caspase-8 activation.

Assembly of a death-inducing signaling complex is a key event in the extrinsic apoptotic pathway, enabling activation of the caspase cascade and subsequent cell death. However, the molecular events governing DISC assembly have remained largely elusive because of the lack of information on mechanism and specificity regulating the death effector domain (DED)-DED interaction network. Using molecular modeling, mutagenesis, and biochemical and ex vivo experiments, we identified the precise binding interface and hot spots crucial for intermolecular DED chain assembly. Mutation of key interface residues (Leu42/Phe45) in procaspase-8 DED-A completely abrogated DED chain formation in HEK293 cells and prevented its association with FADD. A significant 2.6-3.6-fold reduction in procaspase-8 activation was observed in functional cell-death assays after substitution of the interfacial residues. Based on our results we propose a new model for DISC formation that refines the current understanding of the activation mechanism. Upon stimulation, FADD self-associates weakly via reciprocal interaction between helices α1/α4 and α2/α3 of the DED to form an oligomeric signaling platform that provides a stage for the initial recruitment of procaspase-8 through direct interaction with α1/α4 of DED-A, followed by sequential interaction mediated by helices α2/α5 of DED-B, to form the procaspase-8 DED chain that is crucial for its activation and subsequent cell death.

Chalcogen Atom Interaction with Palladium and the Complex Molecule–Metal Interface in Thiol Self Assembly

In the case of reactive metals, on adsorption of organic chalcogenide molecules like thiols, chalcogenide-C bond scission can occur. Thus, the high reactivity of Pd leads to initial thiol dissociation and formation of a complex PdS interface layer on which thereafter thiol self-assembled monolayers (SAM) can form. In this context we investigate in detail the adsorption of S, Se, alkanethiols, and aromatic dithiols on Pd by photoemission with synchrotron radiation. The nature of the PdS and PdSe layers formed is studied, and thiol adsorption on Pd(111), PdS, and PdSe surfaces is investigated, along with interface characteristics. After initial strong sulfidation (selenization) in Na2S(Se) solutions, a well-ordered surface PdS (PdSe) layer can be obtained by annealing. For S, annealing leads to formation of a PdS (√7 × √7)R19.1° layer, whereas for Se, large domains of this structure are formed. Experiments suggest that in thiol adsorption the Pd–sulfide interface is not simply similar to the (√7 × √7)R19.1° PdS layer but that modifications in this surface sulfide layer are induced. A similar effect is observed on the selenide interface layer. In addition, 1,4-benzenedimethanethiol adsorption on Pd is investigated with the aim of creation of thiol-terminated dithiol molecular layers. Unlike the case of surfaces like Au, no clear indication of a standing-up, thiol-terminated SAM was found. X-ray radiation damage effects are reported.

Experimental investigation of high temperature thermal contact resistance between high thermal conductivity C/C material and Inconel 600

Abstract Thermal contact resistance at the assembly interface plays an important role in high temperature structure design and safety assessment. Thermal contact resistance between high thermal conductivity C/C material and superalloy Inconel 600 was experimentally investigated in the present paper. They are widely used in thermal protection structures of heat-pipe-cooled leading edges to enhance interface heat transfer. Results showed that thermal contact resistance between the two materials is about 5 × 10−5 m2 K/W, and it is necessary to take into account the effect of the thermal contact resistance in high thermal conductivity C/C material related thermal structure design.

Structural insights into RNA encapsidation and helical assembly of the Toscana virus nucleoprotein

Toscana virus is an emerging bunyavirus in Mediterranean Europe where it accounts for 80% of pediatric meningitis cases during the summer. The negative-strand ribonucleic acid (RNA) genome of the virus is wrapped around the virally encoded nucleoprotein N to form the ribonucleoprotein complex (RNP). We determined crystal structures of hexameric N alone (apo) and in complex with a nonameric single-stranded RNA. RNA is sequestered in a sequence-independent fashion in a deep groove inside the hexamer. At the junction between two adjacent copies of Ns, RNA binding induced an inter-subunit rotation, which opened the RNA-binding tunnel and created a new assembly interface at the outside of the hexamer. Based on these findings, we suggest a structural model for how binding of RNA to N promotes the formation of helical RNPs, which are a characteristic hallmark of many negative-strand RNA viruses.

Long α helices projecting from the membrane as the dimer interface in the voltage-gated H+ channel

The voltage-gated H(+) channel (Hv) is a H(+)-permeable voltage-sensor domain (VSD) protein that consists of four transmembrane segments (S1-S4). Hv assembles as a dimeric channel and two transmembrane channel domains function cooperatively, which is mediated by the coiled-coil assembly domain in the cytoplasmic C terminus. However, the structural basis of the interdomain interactions remains unknown. Here, we provide a picture of the dimer configuration based on the analyses of interactions among two VSDs and a coiled-coil domain. Systematic mutations of the linker region between S4 of VSD and the coiled-coil showed that the channel gating was altered in the helical periodicity with the linker length, suggesting that two domains are linked by helices. Cross-linking analyses revealed that the two S4 helices were situated closely in the dimeric channel. The interaction interface between the two S4 and the assembly interface of the coiled-coil domain were aligned in the same direction based on the phase angle calculation along α helices. Collectively, we propose that continuous helices stretching from the transmembrane to the cytoplasmic region in the dimeric interface regulate the channel activation in the Hv dimer.

Redesigning the procaspase‐8 dimer interface for improved dimerization

Caspase-8 is a cysteine directed aspartate-specific protease that is activated at the cytosolic face of the cell membrane upon receptor ligation. A key step in the activation of caspase-8 depends on adaptor-induced dimerization of procaspase-8 monomers. Dimerization is followed by limited autoproteolysis within the intersubunit linker (IL), which separates the large and small subunits of the catalytic domain. Although cleavage of the IL stabilizes the dimer, the uncleaved procaspase-8 dimer is sufficiently active to initiate apoptosis, so dimerization of the zymogen is an important mechanism to control apoptosis. In contrast, the effector caspase-3 is a stable dimer under physiological conditions but exhibits little enzymatic activity. The catalytic domains of caspases are structurally similar, but it is not known why procaspase-8 is a monomer while procaspase-3 is a dimer. To define the role of the dimer interface in assembly and activation of procaspase-8, we generated mutants that mimic the dimer interface of effector caspases. We show that procaspase-8 with a mutated dimer interface more readily forms dimers. Time course studies of refolding also show that the mutations accelerate dimerization. Transfection of HEK293A cells with the procaspase-8 variants, however, did not result in a significant increase in apoptosis, indicating that other factors are required in vivo. Overall, we show that redesigning the interface of procaspase-8 to remove negative design elements results in increased dimerization and activity in vitro, but increased dimerization, by itself, is not sufficient for robust activation of apoptosis.

Lumbar transpedicular implant failure: a clinical and surgical challenge and its radiological assessment.

Study DesignIt is a multicenter, controlled case study review of a big scale of pedicle-screw procedures from January 2000 to June 2010. The outcomes were compared to those with no implant failure.PurposeThe purpose of this study was to review retrospectively the outcome of 100 patients with implant failure in comparison to 100 control-patients, and to study the causes of failure and its prevention.Overview of LiteratureTranspedicular fixation is associated with risks of hardware failure, such as screw/rod breakage and/or loosening at the screw-rod interface and difficulties in the system assembly, which remain a significant clinical problem. Removal or revision of the spinal hardware is often required.MethodsTwo hundred patients (88 women, 112 men) were divided into 2 major groups, with 100 patients in group I (implant failure group G1) and 100 patients in group II (successful fusion, control group G2). We subdivided the study groups into two subgroups: subgroup a (single-level instrumented group) and subgroup b (multilevel instrumented group). The implant status was assessed based on intraoperative and follow-up radiographs.ResultsImplant failure in general was present in 36% in G1a, and in 64% in G1b, and types of implant failure included screw fracture (34%), rod fracture (24%), rod loosening (22%), screw loosening (16%), and failure of both rod and screw (4%). Most of the failures (90%) occurred within 6 months after surgery, with no reported cases 1 year postoperatively.ConclusionsWe tried to address the problem and study the causes of failure, and proposed solutions for its prevention.

Design Method of Under-body Platform Automotive Framing Systems

OEMs across the globe are moving to reduce the number of their platform by 50% and to focus more on selected platforms to be used to design and produce different vehicles across segments and brands on a global scale (by size and price range) [1]. OEMs focused on platform sharing and standardization to rationalize their product development and production costs, besides significantly reducing the product-conception-to- launch time. As platform development costs, account for nearly half of the cost product development, this strategy of using common engineering across vehicle models allows money as well as time savings. This research introduces new systematic framework and methods dealing with a complete end-to-end design process of the production system for under-body platform complete in body and white (BIW). This method helps product developer and systems engineer to plan modular development (product upgrades) and interface for both manufacturing and final assembly of production systems. This research introduces new tools such Hybrid Design Structure Matrix (HDSM) to help system designers to understand changes in product design and mapping to physical domains (production systems) and to evaluate the effect of changes by connecting the process to digital manufacturing (DM) simulation. The methods will introduce a new approach to vehicle production systems design and development of “underbody platform” (BIW) using modular assembly strategy.

Charged Residues on the Intracellular Intersubunit Assembly Interface Contribute to Calcium-Sensitivity of BK Channels

The large-conductance calcium-activated K+ (BK) channel contains a large C-terminal intracellular Ca2+-sensing region formed by two RCK domains. The RCK2 domain harbors a Ca2+-binding site of clustered negatively charged residues, known as the Ca2+-bowl, while the RCK1 domain is believed to contain another Ca2+-binding site (RCK1-site). Recent X-ray crystallographic structures of the Ca2+-free and -bound intracellular regions revealed an interesting location of the Ca2+-bowl near the tertrameric intersubunit assembly interface. We investigated the role of the intersubunit assembly interface on Ca2+-gated BK channel activation through mutational analyses of charged residues Glu955, Glu956, Arg786, and Arg790 which may electrostatically stabilize RCK2 intersubunit interactions by formation of intersubunit salt-bridges. We observed that mutations E955Q, E956Q, and E955Q/E956Q caused ∼50%, ∼30%, and ∼70% loss, respectively, of Ca2+-sensitivity as determined at 0, 7.3, and 90.4 μM internal free Ca2+. Combined analyses with Ca2+-bowl or RCK1-site null mutations indicated that E955Q mutation eliminated most Ca2+-sensitivity from the Ca2+-bowl and ∼50% sensitivity from the RCK1-site. The charge neutralization mutation R786A/R790A on the interacting subunits also led to ∼50% loss of Ca2+-sensitivity, suggesting involvement of intersubunit salt-bridge(s) between residues E955 and R786 or R790. Furthermore, intersubunit charge reversal mutations induced recovery of Ca2+-sensitivity. In contrast to the drastic effects of these charged residue mutations, which are located distant (≥20A) to the bound Ca2+, mutation of the Asn449 residue, which may coordinate the RCK2 Ca2+ from a different subunit, displayed little effect on Ca2+-sensitivity. We conclude that the intersubunit interfacial electrostatic interactions play an important role in Ca2+-dependent BK channel gating. We propose that such interactions are unlikely to be involved in direct Ca2+-binding but may provide intersubunit supporting points to mediate Ca2+-gated RCK gating ring expansion or conformational coupling to channel activation.