DSpace 7
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Recent Submissions
Resistance of 3D - printed PVA filaments to bacterial degradation
(Plovdiv University Press "Paisii Hilendarski", 2025-11-20) Bashev, Anton; Assenov, Stanislav
This study systematically evaluates the resistance of 3D-printed PVA filaments (Bambu Lab) to bacterial biodegradation and their potential antimicrobial activity against two widespread environmental strains: Bacillus subtilis (Gram-positive) and Pseudomonas aeruginosa (Gram-negative). Using the standardized agar diffusion method, a 15% PVA solution was tested against a positive control (gentamicin). The results showed no inhibition zones around the PVA samples for either bacterial strain, which clearly confirmed the lack of statistically significant antimicrobial activity (p > 0.05). These findings unambiguously demonstrate that under the experimental conditions, the 3D-printed PVA material not only lacks bactericidal or bacteriostatic properties but also exhibits resistance to the metabolism of the test microorganisms. From an engineering and ecological perspective, this implies that although PVA is water-soluble, its ultimate biodegradation in nature may be slow and inefficient in the absence of specialized microbial consortia. Consequently, the widespread use of PVA in 3D printing could contribute to its accumulation in soil and aquatic ecosystems. This highlights the need for a re-evaluation of its environmental compatibility and the development of improved composite formulations or end of life management strategies aimed at ensuring true biodegradability.
The Question of the Origin and Grammaticalization of the Lexeme One (един)
(Plovdiv University Press, 2024) Molinari, Luca
This article proposes a syntactic approach to the process of grammaticalization of word edin (‘one’) from a numeral to an indefinite marker. The grammaticalization of the numeral ‘one’ into an indefinite marker (and, ultimately, into an indefinite article) is very frequent cross-linguistically. Bulgarian is not an exception to this general pat tern: an increasing number of studies recognize that edin has assumed the functions of an indefinite marker. In particular, beyond its numeral function, edin is able to in troduce referents which are known to the speaker but are unknown to the hearer. Moreover, it has also started assuming some features typical of indefinite articles, such as the ability to occur in generic sentences with non-referential interpretation. The present analysis shows that the different functions (numeral, specific indefinite, non-specific indefinite) edin takes up correspond to different categorial statuses with different syntactic properties that can be reconducted to different structural positions inside the nominal expression. The resulting syntactic path of edin is perfectly in line with classical formal accounts of grammaticalization and reflects a process guided by general principles of the economy of language. A formal proposal for the origin of the lexeme edin is also proposed: it is argued to be the result of rebrackeitng of the original word for ‘one’ *in” with its adverbial reinforcer *(j)ed’.
On the Syntax and Semantics of the Bulgarian Subjunctive
(Plovdiv University Press, 2024) Neagu, Anda
This article provides a brief overview of Bulgarian subjunctive structures in both embedded and root clauses. The introduction presents the typology of these structures by showing that Bulgarian belongs to the Balkan Sprachbund and that subjunctive constructions are one of the features characterizing this linguistic union. In terms of their syntactic configuration, subjunctives are visibly formed by means of the subjunctive marker da, followed by the verb inflected for the indicative mood. This par ticle cannot be separated from the verb by other elements (e.g. the subject), and it can co-occur with complementizers like če. Because of these characteristics, da has been analyzed either as a mood marker, or as a low complementizer associated with mo dality. In terms of its usage, the Bulgarian subjunctive is employed in embedded clauses in structures corresponding to Romance-type infinitives, as well as Romance-type subjunctives. In root clauses, it is used to convey different modal meanings (e.g. deontic or epistemic).
Old Church Slavonic Isocolic Structures. Translation of Oration 38 (On the Birth of Jesus) by Gregory of Nazianzus
(Plovdiv University Press, 2024) Grasso, Paola
The use of isocolic structures is one of the most widespread rhetorical devices in Old Church Slavonic literature. A comprehensive contribution to this issue has been offered by Riccardo Picchio, who observed in many Old Church Slavonic texts a large presence of sentences which can be divided into logical-syntactic segments, rhythmically marked by the same number of accents. This paper aims to offer contribution to one aspect of the issue which deserves to be examined more closely: the likely origin of the use of this rhetorical device from contact with Byzantine Christian literature through translations. This article proposes an analysis of the isocolic structures found in Oration 38 (On the Birth of Jesus), composed by Gregory of Nazianzus (329–390), and their rendering in the Old Bulgarian translation, realized between the end of the 9th and the beginning of the 10th century. The present analysis shows that, except for a few cases, the Slavic translator reproduced the isocolic structures of the original text and recreated the same rhythmic effect.
IoT sensor node for ammonia monitoring in livestock
(Plovdiv University Press "Paisii Hilendarski", 2025-11-19) Assenov, Stanislav; Tokmakov, Dimitar; Bekyarova-Tokmakova, Anna; Shotarova, Snezha; Lyubomirov, Slavi
Increased concentrations of ammonia (NH₃) in livestock buildings pose significant risks to animal welfare, environmental sustainability, and worker safety. The current study presents the design and validation of an Internet of Things (IoT) based sensor node to monitor ammonia concentration (NH₃) in real time in agricultural environments. A microcontroller for local data processing and a wireless communication module that transmits measurements to a cloud platform or mobile application. The prototype has been tested both in controlled laboratory conditions and on real livestock farms, demonstrating high accuracy (±5 ppm), low power consumption (battery power and additional solar panel), and resistance in dusty and humid environments. The collected data is analyzed using machine learning algorithms to predict dangerous levels of NH₃ and automate ventilation controls. The results show that the proposed solution offers a cost-effective and scalable approach to reduce NH₃ emissions, improve animal welfare, and ensure regulatory compliance. Future work includes the integration of additional parameters (e.g., temperature, humidity) and implementation in smart farming systems.