Nanostructured 3D Constructs Based on Chitosan and Chondroitin Sulphate Multilayers for Cartilage Tissue Engineering

Nanostructured three-dimensional constructs combining layer-by-layer technology (LbL) and template leaching were processed and evaluated as possible support structures for cartilage tissue engineering. Multilayered constructs were formed by depositing the polyelectrolytes chitosan (CHT) and chondroitin sulphate (CS) on either bidimensional glass surfaces or 3D packet of paraffin spheres. 2D CHT/CS multi-layered constructs proved to support the attachment and proliferation of bovine chondrocytes (BCH). The technology was transposed to 3D level and CHT/CS multi-layered hierarchical scaffolds were retrieved after paraffin leaching. The obtained nanostructured 3D constructs had a high porosity and water uptake capacity of about 300%. Dynamical mechanical analysis (DMA) showed the viscoelastic nature of the scaffolds. Cellular tests were performed with the culture of BCH and multipotent bone marrow derived stromal cells (hMSCs) up to 21 days in chondrogenic differentiation media. Together with scanning electronic microscopy analysis, viability tests and DNA quantification, our results clearly showed that cells attached, proliferated and were metabolically active over the entire scaffold. Cartilaginous extracellular matrix (ECM) formation was further assessed and results showed that GAG secretion occurred indicating the maintenance of the chondrogenic phenotype and the chondrogenic differentiation of hMSCs

UDC 004.416 ALMA versus DDD

Abstract. To be a debugger is a good thing! Since the very beginning of the programming activity, debuggers are the most important and widely used tools after editors and compilers; we completely recognize their importance for software development and testing. Debuggers work at machine level, after the compilation of the source program; they deal with assembly, or binary-code, and are mainly data structure inspectors. Alma is a program animator based on its abstract representation. The main idea is to show the algorithm being implemented by the program, independently from the language used to implement it. To say that ALMA is a debugger, with no value added, is not true! ALMA is a source code inspector but it deals with programming concepts instead of machine code. This makes possible to understand the source program at a conceptual level, and not only to fix run time errors. In this paper we compare our visualizer/animator system, ALMA, with one of the most well-known and used debuggers, the graphical version of GDB, the DDD program. The aim of the paper is twofold: the immediate objective is to prove that ALMA provides new features that are not usually offered by debuggers; the main contribution is to recall the concepts of debugger and animator, and clarify the role of both tools in the field of program understanding, or program comprehension

UDC 004.43 Program Comprehension for Domain-Specific Languages *

Abstract. In the past, we have been looking for program comprehension tools that are able to interconnect operational and behavioral views, aiming at aiding the software analyst to relate problem and program domains in order to reach a full understanding of software systems. In this paper we are concerned with Program Comprehension issues applied to Domain Specific Languages (DSLs). We are now willing to understand how techniques and tools for the comprehension of traditional programming languages fit in the understanding of DSLs. Being the language tailored for the description of problems in a specific domain, we believe that specific visualizations (at a higher abstraction level, closer to the problem level) could and should be defined to enhance the comprehension of the descriptions in that particular domain

Comparing Generators for Language-based Tools

Abstract. The first step in any language development project is the Compiler Generator choice. Nowadays there are many offers, based on translation grammars, attribute grammars or other language specification formalisms. To make up a decision, more factors than just the tool user-friendliness and the processor’s quality should be taken into account. To aid the language developer, we analyze in this paper three Compiler Generators. The traditional and well known YACC, and two more recent ones, LISA and AnTLR-3. The first produces a Syntax-Directed Translator, while the others generate a Semantic-Directed Translator based on attribute evaluation. Moreover both the AG-based generators also produce other Language-based Tools that are mentioned and compared.

UDC 004.439, DOI: 10.2298/CSIS1002265O VisualLISA: A Visual Environment to Develop Attribute Grammars

Abstract. The focus of this paper is on crafting a new visual language for attribute grammars (AGs), and on the development of the associated programming environment. We present a solution for rapid development of VisualLISA editor using DEViL. DEViL uses traditional attribute grammars, to specify the language’s syntax and semantics, extended by visual representations to be associated with grammar symbols. From these specifications a visual programming environment is automatically generated. In our case, the environment allows us to edit a visual description of an AG that is automatically translated into textual notations, including an XML-based representation for attribute grammars (X AGra), and is intended to be helpful for beginners and rapid development of small AGs. X AGra allows us to use VisualLISA with other compiler-compiler tools