Complete Structural Model Research Articles

Investigation and prediction of solder joint failure analysis for ball grid array package subject to mechanical bending environment

PurposeThe purpose of this study was to investigate the changes in solder joint stress when subjected to mechanical bending. The analytical theory pertaining to the stresses in the solder joint between the components (including the molding compound, the chip and the substrate) was described, and the printed circuit board (PCB) with a discontinuity function when the PCB assembly is subjected to mechanical bending was developed. Thus, the findings reported here may lead to a better understanding of the solder joint failure based on the Physics of Failure model.Design/methodology/approachThis paper discusses the analytical model for calculating the stress in solder joints, as well as presents a simulation model that can be used for calculating the strain energy density of solder joint. First, the multilayer plate theory is used in discussing the composite material for the component, including the molding compound, the silicon chip and the substrate, or the PCB, including the copper layers, the fiber and the epoxy. Finally, the complete structure of the analytical model developed as a part of this current work is presented.FindingsFor the analytical model of multilayer structures in which the interconnection layer is discrete, mechanical bending has been modeled with respect to varying silicon chip length. The analytical model that describes the stress of the outermost solder joint experiences is chosen, as this is the typical solder joint failure. The analytical model can be applied to discrete solder joints, which are evaluated by calculating the matrix form. Owing to its use of the matrix equation, the analytical model can be highly combinatorial and thus more capable of calculating the solution.Research limitations/implicationsThe analytical solution based on a simple concept was presented and validated using the finite element model for the stress experienced by solder joints subjected to mechanical bending. To verify that the simulation represents a real PCB case, the authors use the finite element method (FEM) to compare their case with the multilayer plate theory. Owing to the good agreement between the theory and simulation results, the authors conclude that the multilayer plate theory can be correctly applied in multilayer PCB and be used in an analytical model for the PCB assembly subjected to mechanical bending.Practical implicationsOwing to the good agreement between the theory and simulation results, the authors conclude that the multilayer plate theory can be correctly applied in multilayer PCB and be used in an analytical model for the PCB assembly subjected to mechanical bending.Social implicationsThe analytical model is validated with the FEM model and provides the way to physically examine the solder joint failure mechanism. In this paper, the analytical model is developed as a means to assess the solder joint stress subjected to mechanical bending.Originality/valueThe analytical model treats the solder joint as discrete and has been successfully validated against the finite element model. The complete structure model (the second analytical model) is presented to discuss the effects of varying silicon chip length on the normal stress in solder joints. When the silicon chip length exceeds to 80 per cent of the total package length, the stress of the outermost solder joint increases rapidly. The design analysis findings have suggested that the failure of the outermost solder joint subjected to mechanical bending on the PCB assembly can be reduced by analyzing the analytical model.

Wisdom Gained? Assessing Relationships Between Adversity, Personality and Well-Being Among a Late Adolescent Sample.

How do late adolescents make sense of stressful life events they have experienced in their lives? In a sample of 1320 college students, 676 (58% White, 63% female) reported the stressful events they had experienced in their lifetime up until the present survey and indicated whether they considered each stressful event to be a turning point and/or an opportunity for wisdom. Students also completed measures of personality and well-being. We hypothesized that the tendency to interpret stressful events as turning points or opportunities for wisdom would explain the associations between three personality characteristics (Openness to Experience, Extraversion, and Emotionality) and well-being. We used a multi-step ESEM approach in which we first assessed the measurement structure of our items before testing partial and complete structural models. We tested partial and structural models according to extant guidelines associated with the evaluation of indirect effects models. We did not find support for the indirect effects model, but Openness was associated with the tendency to view stressful events as turning points, and Openness and Extraversion were associated with the tendency to view stressful events as leading to wisdom, as well as with increased well-being.

Spectroscopic Studies of a Bacterial Cyclic Nucleotide-Gated Ion Channel

Cyclic nucleotide-gated (CNG) channels are members of the Kv channel superfamily and play a crucial role in the phototransduction and olfactory transduction pathways, where they generate the initial electrical signal following sensory transduction. CNG channels are directly regulated by cyclic nucleotides, which bind to a C-terminal cyclic nucleotide-binding domain (CNBD) connected to the pore by an intervening C-linker domain. Mutagenesis and crosslinking experiments indicate that the C-terminal region (C-linker/CNBD) undergoes a conformation change to transduce cyclic nucleotide binding into channel activation, though the exact nature of this change remains unclear. To address this question, we first sought a stable and well-behaved bacterial CNG channel suitable for spectroscopic studies. We used fluorescence-detection size-exclusion chromatography to screen a library of bacterial orthologs, which identified several candidates that could be expressed and purified at high levels. Flux studies of liposome-reconstituted channels demonstrated that these orthologs are fully functional and are activated by cyclic nucleotides. We then mutated the endogenous Cys residues in these channels before introducing Cys residues throughout the C-terminal region for spin label and fluorophore attachment. Inter-subunit double electron-electron resonance (DEER) measurements will be used to detect large-scale structural changes in these channels induced by cyclic nucleotide binding, while transition metal FRET (tmFRET) will be used to characterize subtle, localized changes to channel structure following activation. Our ultimate goal is to use these two spectroscopic techniques to characterize small- and large-scale rearrangements induced by cyclic nucleotide binding, allowing us to generate a complete structural model for CNG channel activation.

Optical analysis and output evaluation for a two-stage concentration photovoltaic system by using Monte Carlo ray-tracing method

A two-stage reflecting concentration photovoltaic (CPV) system is proposed by this paper. The optical analysis is carried out by using the Monte Carlo ray-tracing (MCRT) method. The relevant probabilistic models required in that method have been established. The effects of the CPV structural parameters on the optical performance are analyzed and a set of the preferred parameter values is obtained. Furthermore, the tracking error and the slope errors of the reflectors are considered in the optical simulation. Their influences on the position and size of the solar image are simulated. Then the scopes those errors should be limited in are proposed through the detailed optical analysis. The complete structural model of the CPV system is finally established. On its basis, the output characteristic of the CPV cell is analyzed in contrast with the flat PV cell. The calculated result shows that the output power of CPV system is higher than that of the flat PV system in some cases. And there is further potential for the CPV system to improve the photoelectric conversion efficiency and reduce the cost.

Assessment of environmental factors affecting software development process using ISM & MICMAC analysis

Changing trends and globalization has given rise to various challenges to the software industry. Today the repute of any software engineering is related to its quality and timely delivery of product. The repute also depends on how the industry keeps in pace with the new expertise and changing market situation. The factors like transparency, recognition, work life balance etc. play an imperative part in preserving the reasonable edge. The ISM is a methodology for interactive learning process. In this method the factors that affect the system directly or indirectly are outlined into a complete structure model. The major advantage of the ISM model is its graphical representations of identified factors in a structured manner is indeed the subject in consideration. As a tool, it organizes the elements affecting the system’s credibility. It also highlights the hierarchical complexity among the factors of the system. The ultimate necessity is to analyze the performance of these factors for their operative application in the execution of software development process. The main objective of this paper is to identify the shared communication of these factors and identify the driving and dependent factors. In this work an ISM model has been prepared to recognize significant factors and their administrative consequences from software release time point of view.

Research on modelling of spatial dynamic structural mechanics and spatio-temporal evolution of coal mine stopes

Original scientific paper Major hazardous accidents in coal mines are basically attributable to a lack of understanding of or the failure to establish a complete spatial structural mechanical model of the stope during the course of exploitation, as well as of the spatial movement over time caused by the mining itself, mining at the wrong time, as well as improper roadway maintenance and advance of the work face. To efficiently study and analyze the mechanism behind major stope disasters, a method based on monitoring the stress and displacement of stopes was adopted to deduce the process whereby the overlying strata fracture, and a method of ascertaining stope stability based on qualitative identification of the dynamics was further proposed. The study found that the stability of stopes during the process of mining the face can be divided into two stages: (1) Unstable stage: i.e. the distance the work face has advanced Lx width of work face L0. These research results provide a basis for reasonable determination of a space-time relationship for the mining process.

Activation of the E3 ubiquitin ligase Parkin.

The PINK1 (phosphatase and tensin homologue-induced putative kinase 1)/Parkin-dependent mitochondrial quality control pathway mediates the clearance of damaged organelles, but appears to be disrupted in Parkinson's disease (PD) [Springer and Kahle (2011) Autophagy 7, 266-278]. Upon mitochondrial stress, PINK1 activates the E3 ubiquitin (Ub) ligase Parkin through phosphorylation of the Ub-like (UBL) domain of Parkin and of the small modifier Ub itself at a conserved residue [Sauvé and Gehring (2014) Cell Res. 24, 1025-1026]. Recently resolved partial crystal structures of Parkin showed a 'closed', auto-inhibited conformation, consistent with its notoriously weak enzymatic activity at steady state [Wauer and Komander (2013) EMBO J. 32, 2099-2112; Riley et al. (2013) Nat. Commun. 4, 1982; Trempe et al. (2013) Science 340, 1451-1455; Spratt et al. (2013) Nat. Commun. 4, 1983]. It has thus become clear that Parkin must undergo major structural rearrangements in order to unleash its catalytic functions. Recent published findings derived from X-ray structures and molecular modelling present a complete structural model of human Parkin at an all-atom resolution [Caulfield et al. (2014) PLoS Comput. Biol. 10, e1003935]. The results of the combined in silico simulations-based and experimental assay-based study indicates that PINK1-dependent Ser65 phosphorylation of Parkin is required for its activation and triggering of 'opening' conformations. Indeed, the obtained structures showed a sequential release of Parkin's intertwined domains and allowed docking of an Ub-charged E2 coenzyme, which could enable its enzymatic activity. In addition, using cell-based screening, select E2 enzymes that redundantly, cooperatively or antagonistically regulate Parkin's activation and/or enzymatic functions at different stages of the mitochondrial autophagy (mitophagy) process were identified [Fiesel et al. (2014) J. Cell Sci. 127, 3488-3504]. Other work that aims to pin-point the particular pathogenic dysfunctions of Parkin mis-sense mutations have been recently disseminated (Fabienne C. Fiesel, Thomas R. Caulfield, Elisabeth L. Moussaud-Lamodiere, Daniel F.A.R. Dourado, Kotaro Ogaki, Owen A. Ross, Samuel C. Flores, and Wolfdieter Springer, submitted). Such a structure-function approach provides the basis for the dissection of Parkin's regulation and a targeted drug design to identify small-molecule activators of this neuroprotective E3 Ub ligase.

Dynamical insights of Mnk2 kinase activation by phosphorylation to facilitate inhibitor discovery.

Mitogen-activated protein kinase-interacting kinases (Mnks) are emerging anticancer targets. Mnks feature unique structural features, enhancing their importance for selective inhibitor discovery. Nonetheless, the lack of structural details obstruct the development of selective Mnk inhibitors. We disclose the first complete structure model of the activated state of Mnk2. Using all-atom accelerated molecular dynamics, we also demonstrate that its activation by phosphorylation grants access to distinct activation loop conformations, steering the inactive-to-active conformational transformation. Then we propose the binding mode of CGP57380 to active Mnk2, and evaluate key interactions that could be critical for future Mnk-targeted inhibitors. Critical insights of the Mnk2 activation process are gained, while providing a platform for designing Mnk-targeted anticancer agents.

Phosphorylation by PINK1 releases the UBL domain and initializes the conformational opening of the E3 ubiquitin ligase Parkin.

Loss-of-function mutations in PINK1 or PARKIN are the most common causes of autosomal recessive Parkinson's disease. Both gene products, the Ser/Thr kinase PINK1 and the E3 Ubiquitin ligase Parkin, functionally cooperate in a mitochondrial quality control pathway. Upon stress, PINK1 activates Parkin and enables its translocation to and ubiquitination of damaged mitochondria to facilitate their clearance from the cell. Though PINK1-dependent phosphorylation of Ser65 is an important initial step, the molecular mechanisms underlying the activation of Parkin's enzymatic functions remain unclear. Using molecular modeling, we generated a complete structural model of human Parkin at all atom resolution. At steady state, the Ub ligase is maintained inactive in a closed, auto-inhibited conformation that results from intra-molecular interactions. Evidently, Parkin has to undergo major structural rearrangements in order to unleash its catalytic activity. As a spark, we have modeled PINK1-dependent Ser65 phosphorylation in silico and provide the first molecular dynamics simulation of Parkin conformations along a sequential unfolding pathway that could release its intertwined domains and enable its catalytic activity. We combined free (unbiased) molecular dynamics simulation, Monte Carlo algorithms, and minimal-biasing methods with cell-based high content imaging and biochemical assays. Phosphorylation of Ser65 results in widening of a newly defined cleft and dissociation of the regulatory N-terminal UBL domain. This motion propagates through further opening conformations that allow binding of an Ub-loaded E2 co-enzyme. Subsequent spatial reorientation of the catalytic centers of both enzymes might facilitate the transfer of the Ub moiety to charge Parkin. Our structure-function study provides the basis to elucidate regulatory mechanisms and activity of the neuroprotective Parkin. This may open up new avenues for the development of small molecule Parkin activators through targeted drug design.

A case study on the treatment of protein SIRAS data.

A case study has been made on the treatment of the SIRAS (single isomorphous replacement with anomalous scattering) data of the originally unknown protein LegC3N. An alternative treatment has been proposed which led to improved results in this particular test case. The treatment involves iterative direct-method SAD (single-wavelength anomalous diffraction) phasing and direct-method-aided model completion, both of which are implanted in the IPCAS (Iterative Protein Crystal-structure Automatic Solution) pipeline. Apart from the experimental data, a simulated SIRAS data set for LegC3N with the derivative data truncated to 5.0 Å resolution has also been tested. SAD phasing and phase/model extension in PHENIX without direct methods failed to solve the structure using these simulated SIRAS data. However, the procedure proposed here involving direct methods in both SAD phasing and phase/model extension led to a nearly complete structure model. This shows the potential ability of treating SIRAS data with a derivative diffracting to lower resolution.

Improved direct-method aided iterative dual-space model completion

It has been proved that direct methods are efficient in providing phase constraints within the dual-space phase-model iterative framework [1]. The program OASIS is used for the direct-method implementation. Two kinds of iterative direct methods are performed by OASIS. One involves the use of SAD/SIR information [2], while the other dose not [3]. Improvements have been made on both kinds of iterative direct methods. First, the Srinivasan's weighting function replaces previously used Sim's weighting function in the direct-method phase derivation leading to better estimation of phases. This affects both kinds of direct-method iteration. Second, the process of the second kind direct-method iteration has been made multi-threaded and parallel. This significantly speeds up the iteration in multi-CPU systems. Finally, a new figure of merit combining the R factor and Srinivasan's weighting function is used to pick up the best partial structure instead of using the R factor alone. The improved procedure has been tested using a set of SIRAS data from the protein LegC3N with Hg-derivative at 5.0Å resolution and native at 2.1Å resolution. With the previous version of OASIS, SAD phasing at 5.0Å resolution was successful but phases were failed to extend to the 2.1Å resolution native data as is described in §3.2 of [1]. However the new version of OASIS has succeeded in extending 5.0Å resolution SAD phases to 2.1Å resolution native phases leading to a nearly complete structure model.

Locating Cu in Zeolite SSZ-13 by Synchrotron PXRD Using Maximum Entropy Method

Efficient elimination of environmentally harmful gaseous NOx compounds from automotive diesel emission remains a challenging task. State-of-the-art zeolites with the chabazite framework containing catalytically active Cu2+ (Cu-SSZ-13) have been commercialized as NOx after-treatment catalysts in diesel-powered vehicles, due to its superior activity, selectivity, and durability.[1] However, to meet current and future legislative demands, continuous improvement is of fundamental interest. Prerequisites for an in depth understanding and further improvements, are detailed complete structural models of the Cu-loaded catalyst. This may be achieved by the use of high resolution synchrotron powder X-ray diffraction (PXRD) and iterative Rietveld analysis and Maximum Entropy Method (MEM). Since the content of Cu2+ is low, a protonated system (H-SSZ-13) and model system with monovalent Ag+ ions (Ag-SSZ-13) are also examined. The protonated and dehydrated H-SSZ-13 shows perfectly empty voids, i.e. no water residue or other non-framework species. The H-SSZ-13 structure is used as the initial model for the MEM calculations. For Ag-SSZ-13 MEM analysis clearly pinpoints the Ag+ ion as being located in the 6-ring shifted into the chabazite cage (Figure 1), consistent with the generally accepted site for Ag+ ions in chabazite and reveals the strength of the iterative Rietveld/MEM analysis. For the more challenging case of Cu-SSZ-13 it was still possible through careful analysis and reasoning to locate two separate positions for the Cu2+ in Cu-SSZ-13 (Figure 1). The B site has been suggested by several other studies, but never confirmed experimentally.[2] This is the most complete structural description of zeolite SSZ-13 with stabilizing and catalytically active Cu2+ ions.[3]

SWISS-MODEL: modelling protein tertiary and quaternary structure using evolutionary information.

Protein structure homology modelling has become a routine technique to generate 3D models for proteins when experimental structures are not available. Fully automated servers such as SWISS-MODEL with user-friendly web interfaces generate reliable models without the need for complex software packages or downloading large databases. Here, we describe the latest version of the SWISS-MODEL expert system for protein structure modelling. The SWISS-MODEL template library provides annotation of quaternary structure and essential ligands and co-factors to allow for building of complete structural models, including their oligomeric structure. The improved SWISS-MODEL pipeline makes extensive use of model quality estimation for selection of the most suitable templates and provides estimates of the expected accuracy of the resulting models. The accuracy of the models generated by SWISS-MODEL is continuously evaluated by the CAMEO system. The new web site allows users to interactively search for templates, cluster them by sequence similarity, structurally compare alternative templates and select the ones to be used for model building. In cases where multiple alternative template structures are available for a protein of interest, a user-guided template selection step allows building models in different functional states. SWISS-MODEL is available at http://swissmodel.expasy.org/.

Structural studies on Si‐N gradient thin layers by grazing incidence X‐ray diffraction

In this paper, the application of combined method – the powerful tool for structure analysis – used for the structure determination of non‐ordered gradient Si‐N thin films is presented. The method is based on the combination of well‐known methods, like radial distribution function (RDF), pair distribution function (PDF) analyses and the Rietveld refinement. The values of radii and number of coordination spheres, obtained from RDF and PDF analyses, were compared to the theoretical values calculated for typical crystalline structures. Then, the most probable model of the hypothetical ‘unit cell’ of the analysed material might be chosen for the Rietveld refinement. In case of the gradient materials and thin films, the structure analysis is more complicated because the experiment has to be prepared in grazing incident X‐ray diffraction geometry. The X‐ray diffraction patterns collected for different angles of the incident beam show different shape, what indicate different kind of order in layers. Finally, it was stated that the Si‐N layers are nonhomogenous, and their structure depends on the penetration depth. Moreover, there was a possibility to create the complete structure model of whole gradient Si‐N thin film. Copyright © 2014 John Wiley & Sons, Ltd.

Mechanistic basis for high stereoselectivity and broad substrate scope in the (salen)Co(III)-catalyzed hydrolytic kinetic resolution.

In the (salen)Co(III)-catalyzed hydrolytic kinetic resolution (HKR) of terminal epoxides, the rate- and stereoselectivity-determining epoxide ring-opening step occurs by a cooperative bimetallic mechanism with one Co(III) complex acting as a Lewis acid and another serving to deliver the hydroxide nucleophile. In this paper, we analyze the basis for the extraordinarily high stereoselectivity and broad substrate scope observed in the HKR. We demonstrate that the stereochemistry of each of the two (salen)Co(III) complexes in the rate-determining transition structure is important for productive catalysis: a measurable rate of hydrolysis occurs only if the absolute stereochemistry of each of these (salen)Co(III) complexes is the same. Experimental and computational studies provide strong evidence that stereochemical communication in the HKR is mediated by the stepped conformation of the salen ligand, and not the shape of the chiral diamine backbone of the ligand. A detailed computational analysis reveals that the epoxide binds the Lewis acidic Co(III) complex in a well-defined geometry imposed by stereoelectronic rather than steric effects. This insight serves as the basis of a complete stereochemical and transition structure model that sheds light on the reasons for the broad substrate generality of the HKR.

Homology modeling and structural validation of tissue factor pathway inhibitor

Blood coagulation is a cascade of complex enzymatic reactions which involves specific proteins and cellular components to interact and prevent blood loss. The coagulation process begins by either “Tissue Dependent Pathway” (also known as extrinsic pathway) or by “contact activation pathway” (also known as intrinsic pathway). TFPI is an endogenous multivalent Kunitz type protease inhibitor which inhibits Tissue factor dependent pathway by inhibiting Tissue Factor:Factor VIIa (TF:FVIIa) complex and Factor Xa. TFPI is one of the most studied coagulation pathway inhibitor which has various clinical and potential therapeutic applications, however, its exact mechanism of inhibition is still unknown. Structure based mechanism elucidation is commonly employed technique in such cases. Therefore, in the current study the generated a complete TFPI structural model so as to understand the mechanistic details of it's functioning. The model was checked for stereochemical quality by PROCHECK-NMR, WHATIF, ProSA, and QMEAN servers. The model was selected, energy minimized and simulated for 1.5ns. The result of the study may be a guiding point for further investigations on TFPI and its role in coagulation mechanism.

Application of δ recycling to electron automated diffraction tomography data from inorganic crystalline nanovolumes

δ Recycling is a simple procedure for directly extracting phase information from Patterson-type functions [Rius (2012). Acta Cryst. A68, 399-400]. This new phasing method has a clear theoretical basis and was developed with ideal single-crystal X-ray diffraction data. On the other hand, introduction of the automated diffraction tomography (ADT) technique has represented a significant advance in electron diffraction data collection [Kolb et al. (2007). Ultramicroscopy, 107, 507-513]. When combined with precession electron diffraction, it delivers quasi-kinematical intensity data even for complex inorganic compounds, so that single-crystal diffraction data of nanometric volumes are now available for structure determination by direct methods. To check the tolerance of δ recycling to missing data-collection corrections and to deviations from kinematical behaviour of ADT intensities, δ recycling has been applied to differently shaped nanocrystals of various inorganic materials. The results confirm that it can phase ADT data very efficiently. In some cases even more complete structure models than those derived from conventional direct methods and least-squares refinement have been found. During this study it has been demonstrated that the Wilson-plot scaling procedure is largely insensitive to sample thickness variations and missing absorption corrections affecting electron ADT intensities.

Description of the Intermediate Length Scale Structural Motifs in Sodium Vanado-phosphate Glasses by Magnetic Resonance Spectroscopies

For the first time, the local and medium range orders in sodium vanado-phosphate glasses have been investigated by advanced magnetic resonance spectroscopy methods. One- and two-dimensional 31P/51V magic angle spinning nuclear magnetic resonance techniques (31P(51V) REAPDOR and 51V(31P) D-HMQC) have been used to monitor the formation of P–O–V5+ bonds and to provide the first accurate description of the intermediate length scale structural motifs in these glasses. The structural model has been completed by the investigation of the chemical environment of the V4+ ions (produced through the partial reduction of V5+ during the melting stage of the glass preparation) using standard continuous wave and advanced pulsed electron paramagnetic resonance techniques (HYSCORE). Finally, the combination of both sets of data leads to the first complete and precise structural model of the alkali vanado-phosphate glass system.

Modeling the Pilot Detection of Time-Varying Aircraft Dynamics

T HE human pilot is typically required to control aircraft in which the dynamics of the vehicle vary with time. This variation may occur naturally as the aircraft changes flight condition, it can be deliberately induced by changes in the stability and command augmentation system (SCAS), or it may result from airframe damage or control system failures. The means by which the pilot is able to accommodate these changes has led to studies describing the “adaptive human pilot,” (e.g., [1–3]). The work in [4] used a simplified pursuit-control model of the human operator derived from the more complete structural pilot model of [5]. The simplification in [4] allowed implementation of an adaptive control structure in computer simulation of control tasks with time-varying controlledelement dynamics as reported in [6]. It is desirable to hypothesize the manner in which the more complete structural model might be employed to explain human pilot detection of time-varying vehicle dynamics. The structural pilot model is shown in Fig. 1 in a form suitable for a simple single-axis task, such as an aircraft/rotorcraft pitch-attitude tracking task. The pilot model includes three feedback loops defined as visual, vestibular, and proprioceptive. For the purposes of this initial discussion, the vestibular loop will be ignored (K _ m 0). A detailed description of each of the elements in the model is given in [5]. Here, with the exception of the element YPF, the elements will only be briefly described. In themajority of applications, the element Ye is a simple gain. The time delay 0 is set to 0.2 s. YNM is a simple second-order transfer function representing the neuromuscular dynamics in the particular limb that is driving the cockpit inceptor (e.g., control stick or rudder pedals). The element YFS represents the cockpit inceptor force/feel system dynamics. Yc represents the vehicle dynamics in the control axis in question (i.e., the transfer function between vehicle pitch attitude and longitudinal control inceptor input ). The proprioceptive feedback element YPF is assumed to be of the form such that

Impact of foreign trade and investment on Nigeria’s textile industry: The case of China

The textile industry in Nigeria is the third largest in Africa after Egypt and South Africa. It is the largest employer of labour in the manufacturing sector. The industry is mainly controlled by large private-sector firms, often with substantial foreign participation. Low productivity levels limit Nigeria’s export possibilities. Nevertheless, the substantially liberated economic environment and the opportunity Nigeria offers to avoid quota restrictions under the Multi Fibre Agreement (MFA), which is not applicable to Nigeria have induced some foreign entrepreneurs, mostly from Asian countries, to establish export-oriented plants. The bilateral trade between Nigeria and China has grown steadily since 1971 as the volume of trade between the two countries in 2009 hit $6.373billion. In order to analyze the effects of higher imports over exports on the textile industry and the aggregate economy, the complete structural model is constructed with market equilibrium identity, such that total supply of agricultural, industrial, and oil sectors equal aggregate demand. The effect of imports on other macroeconomic variables was tested using nth order vector-regressive model. More private investments are highly needed in the Nigerian textile industry to make it internationally competitive. Key words: Competition, innovation, dependency theory, price stabilization, economic growth, research and development, investment, imports.