Plant Engineering Research Articles

Alloy modification and ultrasonic-assisted milling of wear-resistant alloys with defined surfaces

The reduction of CO2 emissions is closely linked to the development of highly efficient and economical steel components in plant and process engineering. To withstand the high combined corrosive, tribological, thermal, and mechanical stresses, wear-resistant coatings tailored to the application and steel grade are used. In addition to the increasing demand to substitute conventional cobalt alloys with nickel alloys, there is also a growing need for defined or functional surfaces of high integrity. Due to high tool wear, milling operations required to produce the complex geometries of the components are often not economically feasible for SMEs. By means of alloy modification of the filler metals for nickel-based plasma build-up welded wear-resistant coatings and by the use of innovative ultrasonic-assisted milling processes more favourable machinability shall be achieved without reducing the wear protection potential. In this paper, the influence of the microstructure and precipitation morphology adjusted by means of alloy modification on the machinability is investigated. This is done based on a wear protection alloy NiCrMoSiFeB (trade name: Colmonoy 56 PTA) typically used for screw machines, which substitutes conventional CoCr alloys (Stellite). Metallurgical investigations and in-situ measurements of occurring process forces and temperatures at the tool cutting edge during milling as well as subsequent investigations of tool wear and surface integrity allow a detailed analysis and correlation between microstructural properties and machinability. For the cast samples, a clear change in the microstructure and hardness can be seen through the addition of Al, Ti, or Nb. These differences lead to an improvement in the machining process for Nb. Al and Ti cause long-needled or star-shaped precipitations and hardness increases, which lead to higher cutting forces and increased tool wear.

Functional Characterization and Catalytic Activity Improvement of Borneol Acetyltransferase from Wurfbainia longiligularis.

In plant secondary metabolite biosynthesis, acylation is a diverse physiological process, with BAHD acyltransferases playing an essential role. Borneol acetyltransferase (BAT) is an alcohol acetyltransferase, which catalyzes borneol and acetyl-CoA to synthesize bornyl acetate (BA). However, the enzymes involved in the biosynthesis of BA have so far only been characterized in Wurfbainia villosa, the studies on the WvBATs have only been conducted in vitro, and the catalytic activity was relatively low. In this research, three genes (WlBAT1, WlBAT2, and WlBAT3) have been identified to encode BATs that are capable of acetylating borneol to synthesize BA in vitro. We also determined that WlBAT1 has the highest catalytic efficiency for borneol-type substrates, including (+)-borneol, (-)-borneol, and isoborneol. Furthermore, we found that BATs could catalyze a wide range of substrate types in vitro, but in vivo, they exclusively catalyzed borneol-type substrates. Through molecular simulations and site-directed mutagenesis, it was revealed that residues D32, N36, H168, N297, N355, and H384 are crucial for the catalytic activity of WlBAT1, while the R382I-D385R double mutant of WlBAT1 exhibited an increasing acylation efficiency for borneol-type substrates in vitro and in vivo. These findings offer key genetic elements for the metabolic engineering of plants and synthetic biology to produce BA.

From Detection to Protection: The Role of Optical Sensors, Robots, and Artificial Intelligence in Modern Plant Disease Management.

In the past decade, there has been a recognized need for innovative methods to monitor and manage plant diseases, aiming to meet the precision demands of modern agriculture. Over the last 15 years, significant advances in the detection, monitoring, and management of plant diseases have been made, largely propelled by cutting-edge technologies. Recent advances in precision agriculture have been driven by sophisticated tools such as optical sensors, artificial intelligence, microsensor networks, and autonomous driving vehicles. These technologies have enabled the development of novel cropping systems, allowing for targeted management of crops, contrasting with the traditional, homogeneous treatment of large crop areas. The research in this field is usually a highly collaborative and interdisciplinary endeavor. It brings together experts from diverse fields such as plant pathology, computer science, statistics, engineering, and agronomy to forge comprehensive solutions. Despite the progress, translating the advancements in the precision of decision-making or automation into agricultural practice remains a challenge. The knowledge transfer to agricultural practice and extension has been particularly challenging. Enhancing the accuracy and timeliness of disease detection continues to be a priority, with data-driven artificial intelligence systems poised to play a pivotal role. This perspective article addresses critical questions and challenges faced in the implementation of digital technologies for plant disease management. It underscores the urgency of integrating innovative technological advances with traditional integrated pest management. It highlights unresolved issues regarding the establishment of control thresholds for site-specific treatments and the necessary alignment of digital technology use with regulatory frameworks. Importantly, the paper calls for intensified research efforts, widespread knowledge dissemination, and education to optimize the application of digital tools for plant disease management, recognizing the intersection of technology's potential with its current practical limitations.

Rapid and In-Field Sensing of Hydrogen Peroxide in Plant by Hydrogel Microneedle Patch.

The rapidly changing climate is exacerbating the environmental stress that negatively impacts crop health and yield. Timely sensing of plant response to stress is beneficial to timely adjust planting conditions, promoting the healthy growth of plants, and improving plant productivity. Hydrogen peroxide (H2O2) is an importantmolecule of signal transduction in plants. However, the common methods for detecting H2O2in plants are associated with certain drawbacks, such as long extraction time, cumbersome steps, dependence on large instruments, and difficulty in realizing in-field sensing. Therefore, it is urgent to establish more efficient detection methods to realize the rapid detection of H2O2 content in plants. In this research, poly (methyl vinyl ether-alt-maleic acid) (PMVE/MA) hydrogel microneedle (MN) patch for rapid extraction of leaf sap are prepared, and the extraction mechanism of PEG-crosslinked PMVE/MA hydrogel MN patch isstudied. A method of rapid detection of H2O2 content in plants based on MN patch with optical detection technology is constructed. The hydrogel MN patch can be usedfor timely H2O2 analysis. This application enables new opportunities in plant engineering, and can be extended to the safety and healthmonitoring of other plants and animals.

Application of Hydrogen Permeation Techniques to Assess the Effect of Inhibitors in Hydrochloric Steel Pickling of Low‐C Steels and Interstitial‐Free Steels

The acid pickling phase, generally entrusted to HCl‐based solutions, plays a fundamental role in the production of low‐C and interstitial‐free steel coils. Very often, however, pickling operations are challenging due to the possible onset of surface defects (underpickling, overpickling, appearance of surface defects, etc.) linked to complex phenomena involving numerous factors, such as acid concentration, Fe ions in solution, temperature, time, steel type, and scale structure. Moreover, the use of inhibitors, which is essential for controlling the pickling process, represents one of the major challenges. Their dosage, although minimal, must be carefully chosen based on the type of processed coils and other plant engineering variables. The flow of hydrogen that is generated on the surface of the steel during etching causes absorption of hydrogen by the metal and its measurement is strictly linked to the phenomena occurring during scale removal. The correlation of data obtained from a Devanathan double‐cell hydrogen permeation system to results of other techniques, such as weight loss, surface analysis, metallography, and electron microscopy shows that this system can be effectively used to indirectly measure the solution aggressiveness. This experimental approach is applied to two industrial steels: a simple carbon base and an interstitial free Ti steel.

Competitiveness of companies in the design, engineering and construction of nuclear power plants

Increasing electricity consumption in the modern world makes the unique nuclear power market. It provides growing secured demand, specific external development factors. However, only four companies involved in the design, engineering, and construction of nuclear power plants (NPPs). The competitiveness of those companies included into M. Porter’s theory framework, but has its own characteristics. The purpose of the study is to determine the specifics of companies competitiveness engaged in the design, engineering, and construction of nuclear power plants, and assess the factors and prospects for their development. Besides, we define the theoretical base of international competitiveness with regard to the specific features of this economic sector, characterise the companies operating on the market, and build a model of the competitiveness formation of four representatives under the domestic factors of development. In conclusion, we will present the prospects for ROSATOM development in an internationally competitive environment. The models of competitiveness formation show the positive impact of investments in human capital, ESG agenda implementation, and long-term prospects of R&D projects. The research provides information for developing the theory of competitiveness and improving the company’s activities in this economic sector.

Investigation of scaling inhibition and biofouling potential of different molecular weight fractions of a PAA antiscalant

This study investigates the scale inhibition performance of a commercial polyacrylic acid-based (PAA) antiscalant used for drinking water production and its molecular weight fractions (≤ 500 Da, ≥ 500 Da). The investigated antiscalant is used to prevent sulfate and carbonate scaling in treatment of drinking water sources by reverse osmosis or nanofiltration (RO/NF). Based on two complementary tests involving determination of induction time in a batch test and rate of flux decline in a lab-scale RO/NF plant, concordant results were obtained, proving that the overall performance of commercial PAA was controlled almost entirely by the higher molecular weight fraction. The low molecular weight fraction, which is potentially more permeable through the NF/RO membrane, showed poor inhibition against both sulfate and carbonate scalants. Furthermore, measurements on the assimilable organic carbon (AOC) by flow cytometry reveals that the low molecular weight PAA fraction has low biological stability, as its potential transport into the permeate of a NF270 nanofiltration membrane was inferred by elevated AOC values in the NF-permeate. These results are crucial information for water utilities, plant engineering, regulatory bodies and public authorities with respect to the possible operation of RO/NF especially in drinking water production.

Strategies, Achievements, and Potential Challenges of Plant and Microbial Chassis in the Biosynthesis of Plant Secondary Metabolites.

Diverse secondary metabolites in plants, with their rich biological activities, have long been important sources for human medicine, food additives, pesticides, etc. However, the large-scale cultivation of host plants consumes land resources and is susceptible to pest and disease problems. Additionally, the multi-step and demanding nature of chemical synthesis adds to production costs, limiting their widespread application. In vitro cultivation and the metabolic engineering of plants have significantly enhanced the synthesis of secondary metabolites with successful industrial production cases. As synthetic biology advances, more research is focusing on heterologous synthesis using microorganisms. This review provides a comprehensive comparison between these two chassis, evaluating their performance in the synthesis of various types of secondary metabolites from the perspectives of yield and strategies. It also discusses the challenges they face and offers insights into future efforts and directions.

Introducing a multipliable BOM-based automatic definition of information retrieval in plant engineering

AbstractThe complexity of process plants and the growing demand for digitalization require efficient and accurate information retrieval throughout the lifecycle phases of a process plant. This paper discusses the concept of instantiation and introduces a method for identifying and multiplying required information in plant engineering using scalable so-called Instantiation Blocks linked to the Bill of Material. Core functionality, an ontology graph and a user interface based on Python and React are developed to demonstrate the implementation of the framework and validate its effectiveness in practice.

Produkt-Service-Systeme im Maschinen- und Anlagenbau

Abstract Mechanical and plant engineering companies that have been focused primarily on product manufacturing in the past are recognizing the potential of a service-oriented business approach as they transform from technology providers to total solution providers. The increasing demand for holistic solutions is driving the development of product-service systems. This article closes a knowledge gap by developing a process model that enables the standardization and transferability of machine-specific product-service systems to entire machine portfolios.

Biochemical characterization of acyl-CoA:diacylglycerol acyltransferase2 from the diatom Phaeodactylum tricornutum and its potential effect on LC-PUFAs biosynthesis in planta

BackgroundEicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), belonging to ω-3 long-chain polyunsaturated fatty acids (ω3-LC-PUFAs), are essential components of human diet. They are mainly supplemented by marine fish consumption, although their native producers are oleaginous microalgae. Currently, increasing demand for fish oils is insufficient to meet the entire global needs, which puts pressure on searching for the alternative solutions. One possibility may be metabolic engineering of plants with an introduced enzymatic pathway producing ω3-LC-PUFAs.ResultIn this study we focused on the acyl-CoA:diacylglycerol acyltransferase2b (PtDGAT2b) from the diatom Phaeodactylum tricornutum, an enzyme responsible for triacylglycerol (TAG) biosynthesis via acyl-CoA-dependent pathway. Gene encoding PtDGAT2b, incorporated into TAG-deficient yeast strain H1246, was used to confirm its activity and conduct biochemical characterization. PtDGAT2b exhibited a broad acyl-CoA preference with both di-16:0-DAG and di-18:1-DAG, whereas di-18:1-DAG was favored. The highest preference for acyl donors was observed for 16:1-, 10:0- and 12:0-CoA. PtDGAT2b also very efficiently utilized CoA-conjugated ω-3 LC-PUFAs (stearidonic acid, eicosatetraenoic acid and EPA). Additionally, verification of the potential role of PtDGAT2b in planta, through its transient expression in tobacco leaves, indicated increased TAG production with its relative amount increasing to 8%. Its co-expression with the gene combinations aimed at EPA biosynthesis led to, beside elevated TAG accumulation, efficient accumulation of EPA which constituted even 25.1% of synthesized non-native fatty acids (9.2% of all fatty acids in TAG pool).ConclusionsThis set of experiments provides a comprehensive biochemical characterization of DGAT enzyme from marine microalgae. Additionally, this study elucidates that PtDGAT2b can be used successfully in metabolic engineering of plants designed to obtain a boosted TAG level, enriched not only in ω-3 LC-PUFAs but also in medium-chain and ω-7 fatty acids.

Attracting Female Engineers: A Qualitative Analysis in Mechanical Engineering in Germany

The number of women working as engineers in the mechanical and plant engineering sector in Germany has risen to eleven percent in 2023 – remaining at humble levels. In higher positions, the share is even lower. While around 20 % of engineering students at German universities are female, these women do not seem to be entering the sector or they are leaving it again. The question arises as to what companies in the mechanical and plant engineering sector can do to attract female engineers after graduation. This study was conducted in cooperation with the German Engineering Association. The aim was to qualitatively explore the reasons why women enter, stay or leave the engineering sector and to include the industry’s perspective to obtain a holistic view of the situation. Therefore, on the one hand the perspective of female engineers was investigated and, on the other hand, combined with the perspective of companies. We provide insights from focus groups and interviews with 49 female engineers across all career levels, from an analysis of 90 online company websites and social media pages as well as from three on-site visits at exemplary companies. The findings point to unresolved issues in recruitment and beyond: highlighting role models of successful women in engineering, the need for companies to actively attract and support women in engineering, e. g. through recruiting strategies focusing on women, insights into the working culture, and transparency regarding career options. Overall, the study suggests that companies should embed gender diversity and group specific recruitment as important issues in their organizations. Consequently, the study provides recommendations for action for companies seeking to become a more inclusive and diverse industry. Limitations are discussed and further implications are presented.

Activation of the native PHYTOENE SYNTHASE 1 promoter by modifying near-miss cis-acting elements induces carotenoid biosynthesis in embryogenic rice callus

Key messageModification of silent latent endosperm-enabled promoters (SLEEPERs) allows the ectopic activation of non-expressed metabolic genes in rice callusMetabolic engineering in plants typically involves transgene expression or the mutation of endogenous genes. An alternative is promoter modification, where small changes in the promoter sequence allow genes to be switched on or off in particular tissues. To activate silent genes in rice endosperm, we screened native promoters for near-miss cis-acting elements that can be converted to endosperm-active regulatory motifs. We chose rice PHYTOENE SYNTHASE 1 (PSY1), encoding the enzyme responsible for the first committed step in the carotenoid biosynthesis pathway, because it is not expressed in rice endosperm. We identified six motifs within a 120-bp region, upstream of the transcriptional start site, which differed from endosperm-active elements by up to four nucleotides. We mutated four motifs to match functional elements in the endosperm-active BCH2 promoter, and this promoter was able to drive GFP expression in callus and in seeds of regenerated plants. The 4 M promoter was not sufficient to drive PSY1 expression, so we mutated the remaining two elements and used the resulting 6 M promoter to drive PSY1 expression in combination with a PDS transgene. This resulted in deep orange callus tissue indicating the accumulation of carotenoids, which was subsequently confirmed by targeted metabolomics analysis. PSY1 expression driven by the uncorrected or 4 M variants of the promoter plus a PDS transgene produced callus that lacked carotenoids. These results confirm that the adjustment of promoter elements can facilitate the ectopic activation of endogenous plant promoters in rice callus and endosperm and most likely in other tissues and plant species.

Analyze of Education and Training Using Ship Engine Simulators at STIP Jakarta Indonesia

On this research paper, we analyze Cadet Engineer, junior engineer, senior level Operational engineers, and senior management level engineers will carry out experiments using speed data from various scenarios on the ship engine simulator and then the experimental results will use educational and training analysis on the ship engine simulator to find out the right time. Later analysis also revealed that human errors occur due to the following reasons: Lack of knowledge of the overall system and fundamental operations, Insufficient confirmation of operations and Incomplete knowledge of the sequence of operations. the role of the instructor will be explained to reduce the causes of human error and to improve educational performance according to the implementation and development of each scenario based on expert justification and reference to IMO and SOLAS Standards. various safety procedure scenarios for all Engineers in the hope of minimizing accidents that cause loss of life at sea. For the purpose of training engine plant operations using a PC-based Engine Room Simulator (ERS), describe the features of human errors by incompetent trainees in marine engine plant operations and demonstrate the necessary improvements in training to reduce such errors from an educational technology point of view. Examination of these data has shown that errors occur primarily due to errors of omission and inadvertent action. Further analysis was carried out on these errors by the engineer trainees to determine the characteristics of errors caused in the process of acquiring procedural knowledge for operations according to the implemented development of various safety scenarios.

Engineering Plant Cell Fates and Functions for Agriculture and Industry.

Many plant species are grown to enable access to specific organs or tissues, such as seeds, fruits, or stems. In some cases, a value is associated with a molecule that accumulates in a single type of cell. Domestication and subsequent breeding have often increased the yields of these target products by increasing the size, number, and quality of harvested organs and tissues but also via changes to overall plant growth architecture to suit large-scale cultivation. Many of the mutations that underlie these changes have been identified in key regulators of cellular identity and function. As key determinants of yield, these regulators are key targets for synthetic biology approaches to engineer new forms and functions. However, our understanding of many plant developmental programs and cell-type specific functions is still incomplete. In this Perspective, we discuss how advances in cellular genomics together with synthetic biology tools such as biosensors and DNA-recording devices are advancing our understanding of cell-specific programs and cell fates. We then discuss advances and emerging opportunities for cell-type-specific engineering to optimize plant morphology, responses to the environment, and the production of valuable compounds.

In-silico characterization of meristem defective (MDF) protein associated with regulation of root meristems in Arabidopsis thaliana

Meristem defective protein (MDF) plays its role in proper development of meristem patterns in Arabidopsis through regulation of auxins homeostasis. It also enables plants to survive in stress. Present study was designed to characterize MDF protein in A. thaliana to get an insight into its molecular aspects. Sequence of protein was retrieved from uniprot database and subjected to CELLO, SOPMA, SWISSMODEL, MEME server and SRING tools. The protein was also docked with four proteins i. e. SR4, RSZ33, PLT1, 2 and 3. The protein was found to localize in nucleus with secondary structure comprising of alpha helix (47.20%), extended strand (6.34%), beta turn (5.37%) and random coil (41.10%). MDF was analyzed as a conserved protein with monomeric structure. Proteins observed as interacting partners of MDF included STA1, T13D8.9, LSM5, LSM2, LSM4 and LSM8. Docking analysis revealed highest and lowest affinities of MDF binding with RS4, RZS33, PLT1, PLT2 and PLT3 in case of FGRTLTPKEAFRLLSHKFHG and IQGQTTHTFEDLNSSAKVSSDYFSQ conserved motifs, respectively. Features of MDF protein explored in this investigation can be exploited for engineering and production of plants with efficient root meristems development.

Auto-Routing Systems (ARSs) with 3D Piping for Sustainable Plant Projects Based on Artificial Intelligence (AI) and Digitalization of 2D Drawings and Specifications

The engineering sector is undergoing digital transformation (DT) alongside shifts in labor patterns. This study concentrates on piping design within plant engineering, aiming to develop a system for optimal piping route design using artificial intelligence (AI) technology. The objective is to overcome limitations related to time and costs in traditional manual piping design processes. The ultimate aim is to contribute to the digitalization of engineering processes and improve project performance. Initially, digital image processing was utilized to digitize piping and instrument diagram (P&ID) data and establish a line topology set (LTS). Subsequently, three-dimensional (3D) modeling digital tools were employed to create a user-friendly system environment that visually represents piping information. Dijkstra’s algorithm was implemented to determine the optimal piping route, considering various priorities during the design process. Finally, an interference avoidance algorithm was used to prevent clashes among piping, equipment, and structures. Hence, an auto-routing system (ARS), equipped with a logical algorithm and 3D environment for optimal piping design, was developed. To evaluate the effectiveness of the proposed model, a comparison was made between the bill of materials (BoM) from Company D’s chemical plant project and the BoM extracted from the ARS. The performance evaluation revealed that the accuracy in matching pipe weight and length was 105.7% and 84.9%, respectively. Additionally, the accuracy in matching the weight and quantity of fittings was found to be 99.7% and 83.9%, respectively. These findings indicate that current digitalized design technology does not ensure 100% accurate designs. Nevertheless, the results can still serve as a valuable reference for attaining optimal piping design. This study’s outcomes are anticipated to enhance work efficiency through DT in the engineering piping design sector and contribute to the sustainable growth of companies.

Developing Drought Tolerance in Field Crops towards Current Century: An Integrated Bio-Molecular Approach

Drought stresses are foremost threat to plant growth, productivity as well as sustainability towards agriculture through worldwide. Some of the classical breeding approaches have been attempted to develop crop performance towards stress without significant success and so therefore, recently genetic engineering in crop plants is recognized as an alternative strategy to generate drought tolerant crop plants. Various integrated biological approaches have been undertaken to overcome such drought hurdles in achieving the full potentiality of the plant growth and production as well as improving the drought tolerance in different field crops. Some approaches are commonly used to identify genes related to drought tolerance and genes to be identified which are involved in processes known to be critical for drought tolerance; whose expression is regulated by drought stress and that consists in the identification of drought tolerance determinants based on functionality. Plant researchers have developed several spurts of biological novel ‘Omics’ technologies viz. genomics, transcriptomics, proteomics and metabolomics etc to engineer plant stress tolerance. In this review, an attempt has been made to summarize the current information based on recent literature towards recent understanding as well as latest advancement related to the adverse effect of plant under drought and their adaptations or tolerance towards such abiotic stress with a focus on the identification of drought tolerance mechanisms by soil management practices, crop establishment and exogenous application of growth regulators by regulating an appropriate level of water due to osmotic adjustment and stomatal performance etc at an integrated biological level of approach.

The Impact of Innovative Research Methods for Enhancing Agricultural Plants for Sustainable Development in The Future

In the pursuit of sustainable agricultural practices, the role of innovative research methods in enhancing agricultural plants is paramount. This abstract delineates the profound impact of such methodologies on sustainable development in the foreseeable future. Cutting-edge techniques such as genomic sequencing, molecular markers, and genome editing technologies revolutionize plant breeding by identifying and manipulating genes responsible for desirable traits, including disease resistance and drought tolerance. Omics technologies, encompassing transcriptomics, proteomics, and metabolomics, provide comprehensive insights into gene expression patterns and metabolic pathways, thereby facilitating targeted breeding strategies aimed at enhancing plant resilience and productivity. High-throughput phenotyping platforms enable rapid and accurate characterization of plant traits, empowering breeders to select superior varieties with enhanced performance under diverse environmental conditions. Concurrently, bioinformatics tools and data analytics play a pivotal role in deciphering complex genomic datasets, aiding in the identification of key genes and regulatory networks governing important agronomic traits. Biotechnology and synthetic biology approaches offer novel avenues for genetic manipulation, allowing for the design and engineering of plants with optimized traits, such as improved nutritional content and stress tolerance. Additionally, the integration of climate modeling with systems biology provides valuable insights into the interaction between genotype and environment, facilitating the development of climate-resilient crop varieties tailored to specific agroecosystems. Through the synergistic application of these innovative research methods, agricultural scientists and breeders can accelerate the pace of crop improvement while simultaneously promoting sustainability by fostering resilience, resource efficiency, and environmental stewardship. This transformative paradigm in agricultural research promises to address the complex challenges of food security, climate change, and environmental degradation, thereby laying the foundation for a more sustainable and resilient agricultural future.

Vom Verein zum Unternehmen?

Abstract Using the example of the German Mechanical and Plant Engineering Association (Verband Deutscher Maschinen- und Anlagenbau, VDMA), this paper examines the viability of corporate history approaches in the history of the associations. The VDMA, one of the largest trade associations in the Federal Republic of Germany, faced increasing criticism from its member companies in the late 60s. The complex organisation, which had to reconcile the interests of some three dozen branches of industry and various regional groups, was considered inefficient and lacking in profile. The reaction was to launch a reform programme with rationalisation measures, a modern image policy and an expansion of the range of services on offer that showed certain traits of entrepreneurial behaviour. At the same time, the dues system was reformed, but the introduction of a splitting of the dues to the association’s headquarters and the branches was dispensed in order not to endanger the cohesion of interests. Both areas of reform thus demonstrate the imits of entrepreneurial logic in the organisation of an association.