Repair Activity Research Articles

The Role of Key Amino Acids of the Human Fe(II)/2OG-Dependent Dioxygenase ALKBH3 in Structural Dynamics and Repair Activity toward Methylated DNA.

Non-heme dioxygenases of the AlkB family hold a unique position among enzymes that repair alkyl lesions in nucleic acids. These enzymes activate the Fe(II) ion and molecular oxygen through the coupled decarboxylation of the 2-oxoglutarate co-substrate to subsequently oxidize the substrate. ALKBH3 is a human homolog of E. coli AlkB, which displays a specific activity toward N1-methyladenine and N3-methylcytosine bases in single-stranded DNA. Due to the lack of a DNA-bound structure of ALKBH3, the basis of its substrate specificity and structure-function relationships requires further exploration. Here we have combined biochemical and biophysical approaches with site-directed mutational analysis to elucidate the role of key amino acids in maintaining the secondary structure and catalytic activity of ALKBH3. Using stopped-flow fluorescence spectroscopy we have shown that conformational dynamics play a crucial role in the catalytic repair process catalyzed by ALKBH3. A transient kinetic mechanism, which comprises the steps of the specific substrate binding, eversion, and anchoring within the DNA-binding cleft, has been described quantitatively by rate and equilibrium constants. Through CD spectroscopy, we demonstrated that replacing side chains of Tyr143, Leu177, and His191 with alanine results in significant alterations in the secondary structure content of ALKBH3 and decreases the stability of mutant proteins. The bulky side chain of Tyr143 is critical for binding the methylated base and stabilizing its flipped-out conformation, while its hydroxyl group is likely involved in facilitating the product release. The removal of the Leu177 and His191 side chains substantially affects the secondary structure content and conformational flexibility, leading to the complete inactivation of the protein. The mutants lacking enzymatic activity exhibit a marked decrease in antiparallel β-strands, offset by an increase in the helical component.

Adoption of classification and cataloging techniques in the maintenance industry

In this article, the author attempts to implement and adopt the idea of library classification and cataloging tools and spares in the maintenance sector To open unexplored sectors of usage and operations. The maintenance sector is crucial in keeping and maintaining equipment, comprehending the various techniques and procedures to ensure the smooth functioning of assets or equipment. Understand different types of servicing and examine the material, tools, and testers' requirements for various repair and maintenance activities. To understand the level of library method implementation in multiple aspects and study the infusion results with relevant examples. Understand the implementation, modification, and adoption of Dewy Decimal Classification and the applicability of library methods in the maintenance sector.

Dose-Dependent Transcriptional Response to Ionizing Radiation Is Orchestrated with DNA Repair within the Nuclear Space.

Radiation therapy is commonly used to treat glioblastoma multiforme (GBM) brain tumors. Ionizing radiation (IR) induces dose-specific variations in transcriptional programs, implicating that they are tightly regulated and critical components in the tumor response and survival. Yet, our understanding of the downstream molecular events triggered by effective vs. non-effective IR doses is limited. Herein, we report that variations in the genetic programs are positively and functionally correlated with the exposure to effective or non-effective IR doses. Genome architecture analysis revealed that gene regulation is spatially and temporally coordinated with DNA repair kinetics. The radiation-activated genes were pre-positioned in active sub-nuclear compartments and were upregulated following the DNA damage response, while the DNA repair activity shifted to the inactive heterochromatic spatial compartments. The IR dose affected the levels of DNA damage repair and transcription modulation, but not the order of the events, which was linked to their spatial nuclear positioning. Thus, the distinct coordinated temporal dynamics of DNA damage repair and transcription reprogramming in the active and inactive sub-nuclear compartments highlight the importance of high-order genome organization in synchronizing the molecular events following IR.

Analisa Risiko Keselamatan Dan Kesehatan Kerja (K3) Pada Kegiatan Docking Di PT. Pelindo Marine Service

The importance of K3 aspects in docking activities not only includes individual safety, but also has a direct impact on productivity and operational continuity. Accidents or incidents that occur during the docking process can not only threaten the lives and health of workers, but can also cause detrimental environmental impacts and hinder the smooth running of the supply chain. The HIRARC method allows identifying various potential hazards that may be associated with an activity or work environment. This approach involves data collection, situational analysis, and determining appropriate mitigation measures. From the results of the identification carried out during ship docking activities at PT. Pelindo Marine Service has 14 activities that have potential danger. With 4 activities that have very low risk, namely maintenance and repair activities in the engine room, ship maintenance in closed rooms, maintenance and repairs in the electrical room, and manual lifting of heavy materials. Then there are 5 activities with low risk, including welding process activities in open spaces, carrying out repair work at height, operating cranes, cleaning ship rooms, and plate cutting (LPG gas cutting) and material grinding processes. 3 activities with medium/medium risk, namely working around waters, working/standing around ships, and stuffing/stripping activities. And there is 1 activity with high risk, namely the ship maintenance process using the welding process in a closed space and 1 activity with very high risk, namely the activity of filling gas cylinders (for cutting and welding equipment). The risks faced include slipping, falling, scratches, shortness of breath, weakness, eye irritation, injuries, minor injuries, serious injuries, sprains, burns, fractures, electrocution and others. And the efforts made to control the risks above include using Personal Protective Equipment with discipline, working according to SOPs, installing K3 signs, providing fire extinguishers, regular inspections and implementing a good ventilation system. Based on the results of risk identification in ship docking activities at PT. Pelindo Marine Services. The importance of effective and continuous implementation of K3 in ship docking activities, in order to maintain the safety, health and welfare of workers and minimize negative impacts on company operations

Dynamics of dimorphic workers of Constrictotermes cyphergaster (Blattodea: Termitidae) during nest repair.

Termite nest repairs are considered a defensive conduct as they reduce the colony's exposure to the external environment. Repair activities are carried out by worker castes that can be polymorphic, representing a relationship between polymorphism and divisions of functions that can enhance task completion. Repairs are influenced by the extent of damage, nest volume, and the population dynamics of the building species, which regulate the recruitment of individuals for this activity. Our objective was to verify the performances (recruitment for repair) of dimorphic workers of Constrictotermes cyphergaster (Silvestri, 1901) during the damage repair activities performed on the external walls of termite nests of different sizes. We found a significant difference in the presence of dimorphic workers that performed repairs, with greater recruitment of the small morphotype, and observed an alternation of morphotypes between initial and final repair activities, with no influence of morphotype on the replacement pattern. Our results also showed that the total number of recruited workers decreased with increasing nest volume. These results help to better understand the social organization of a Nasutitermitinae termite species and the strategies adopted to protect its colonies.

Therapeutic upregulation of DNA repair pathways: strategies and small molecule activators.

DNA repair activity diminishes with age and genetic mutations, leading to a significantly increased risk of cancer and other diseases. Upregulating the DNA repair system has emerged as a potential strategy to mitigate disease susceptibility while minimizing cytotoxic side effects. However, enhancing DNA repair activity presents significant challenges due to the inherent inefficiency in activator screening processes. Additionally, pinpointing a critical target that can effectively upregulate overall repair processes is complicated as the available information is somewhat sporadic. In this review, we discuss potential therapeutic targets for upregulating DNA repair pathways, along with the chemical structures and properties of reported small-molecule activators. We also elaborate on the diverse mechanisms by which these targets modulate repair activity, highlighting the critical need for a comprehensive understanding to guide the development of more effective therapeutic strategies.

Fluorescent molecular rotors detect O6-methylguanine dynamics and repair in duplex DNA.

Alkylation at the O6 position of guanine is a common and highly mutagenic form of DNA damage. Direct repair of O6-alkylguanines by the "suicide" enzyme O6-methylguanine DNA methyltransferase (MGMT, AGT, AGAT) maintains genome stability and inhibits carcinogenesis. In this study, a fluorescent analogue of thymidine containing trans-stilbene (tsT) is quenched by O6-methylguanine residues in the opposite strand of DNA by molecular dynamics that propagate through the duplex with as much as ∼9 Å of separation. Increased fluorescence of tsT or the cytosine analogue tsC resulting from MGMT-mediated DNA repair were distinguishable from non-covalent DNA-protein binding following protease digest. To our knowledge, this is the first study utilizing molecular rotor base analogues to detect DNA damage and repair activities in duplex DNA.

Role and Potential Mechanisms of Nicotinamide Mononucleotide in Aging.

Nicotinamide adenine dinucleotide (NAD+) has recently attracted much attention due to its role in aging and lifespan extension. NAD+ directly and indirectly affects many cellular processes, including metabolic pathways, DNA repair, and immune cell activities. These mechanisms are critical for maintaining cellular homeostasis. However, the decline in NAD+ levels with aging impairs tissue function, which has been associated with several age-related diseases. In fact, the aging population has been steadily increasing worldwide, and it is important to restore NAD+ levels and reverse or delay these age-related disorders. Therefore, there is an increasing demand for healthy products that can mitigate aging, extend lifespan, and halt age-related consequences. In this case, several studies in humans and animals have targeted NAD+ metabolism with NAD+ intermediates. Among them, nicotinamide mononucleotide (NMN), a precursor in the biosynthesis of NAD+, has recently received much attention from the scientific community for its anti-aging properties. In model organisms, ingestion of NMN has been shown to improve age-related diseases and probably delay death. Here, we review aspects of NMN biosynthesis and the mechanism of its absorption, as well as potential anti-aging mechanisms of NMN, including recent preclinical and clinical tests, adverse effects, limitations, and perceived challenges.

Exosomes in Action: Unraveling Their Role in Autoimmune Diseases and Exploring Potential Therapeutic Applications.

Exosomes are double phospholipid membrane vesicles that are synthesized and secreted by a variety of cells, including T cells, B cells, dendritic cells, immune cells, are extracellular vesicles. Recent studies have revealed that exosomes can play a significant role in under both physiological and pathological conditions. They have been implicated in regulation of inflammatory responses, immune response, angiogenesis, tissue repair, and antioxidant activities, particularly in modulating immunity in autoimmune diseases (AIDs). Moreover, variations in the expression of exosome-related substances, such as miRNA and proteins, may not only offer valuable perspectives for the early warning, and prognostic assessment of various AIDs, but may also serve as novel markers for disease diagnosis. This article examines the impact of exosomes on the development of AIDs and explores their potential for therapeutic application.

Based on In Vitro and 3D Epidermal Skin Model: The Efficacy of Bletilla Striata Extract for Skin Care

Introduction: Bletilla Striata (Thunb. ex A. Murray) Rchb. f.) Is a native herb of the orchidaceae family. Modern pharmacological activity studies have shown that Bletilla striata mainly has pharmacological activities such as promoting blood circulation and hemostasis, promoting wound healing anticancer, anti-tumor disease-resistant pathogenic microorganisms, protecting mucosa, anti-ulcer, whitening and anti-oxygen, anti-aging, and immune regulation, which have been widely recognized and applied. Research on the efficacy of plant extracts mainly adopts in vitro testing methods, such as cell experiment and 3D skin model experiment. Objective: To evaluate the soothing effect of Bletilla striata extracton UVB-stimulated keratinocytes (HaCaT) and its barrier repair efficacy in Skinovo-Epi skin model. Methods: The soothing and barrier repairing effects of Bletilla striata extract were studied in vitro. The cytotoxicity of the sample was measured by MTT assay, and cytotoxicity to keratinocytes was evaluated by cell survival rate. The soothing effect was evaluated by detecting changes in inflammatory cytokines (IL-6, IL-1β, IL-8, TNF-α) secreted by UVB-stimulated keratinocytes with the sample treatment. Barrier repair efficacy was assessed in a Skinovo-Epi skin model by measuring changes in FLG (Filaggrin) and LOR (Loricrin) protein levels after topical application of the sample. Results: The sample showed low cytotoxicity on keratinocytes. The sample significantly reduced UVB-stimulated secretion of inflammatory cytokines in keratinocytes. Topical application of the sample increased FLG and LOR protein levels in the Skinovo-Epi skin model. Conclusions:Bletilla striata extract exhibits soothing and barrier repair activities in vitro. Bletilla striata extract reduces UVB-stimulated inflammation in keratinocytes and improves skin barrier function. The data provide novel experimental evidence supporting the innovative application of Bletilla striata for skin disorders. Bletilla striata has potential as a therapeutic herb for sensitive and damaged skin conditions.

Perspectives for the Application of Reinforcement Learning for the Integrated Order-Dispatching and Maintenance Scheduling

Production scheduling involves the efficient allocation of limited resources to perform necessary tasks, while maintenance scheduling aims to proactively plan repair activities to avoid machine breakdowns. Traditionally, various approaches such as heuristics and mathematical programming have been employed to tackle these challenges. However, with the advent of Industry 4.0 technologies and their ability to collect real-time system data, Reinforcement Learning has emerged as a promising solution for integrated scheduling optimization problems. In this context, the present study explores the literature addressing the integration of order-dispatching and maintenance scheduling using Reinforcement Learning. The findings of this research contribute to highlight research opportunities based on the identified gaps in the literature. This paper serves as a steppingstone for future research in this area, providing a foundation for researchers to delve deeper into this integrated problem and explore innovative approaches. Approaches that consider spare parts, technician skills, product quality and different types of transportation, besides incorporating factors such as supply chain parameters, sustainability and energy efficiency, are pointed out as possible research directions in this area. As Industry 4.0 continues to evolve, the application of Reinforcement Learning in production and maintenance scheduling optimization holds great promise for improving industrial practices.

Synergistic Effect of Ubiquitin-Specific Protease 14 and Poly(ADP-Ribose) Glycohydrolase Co-Inhibition in BRCA1-Mutant, Poly(ADP-Ribose) Polymerase Inhibitor-Resistant Triple-Negative Breast Cancer Cells.

The clinical benefits of poly(ADP-ribose) polymerase (PARP) inhibitors are limited to triple-negative breast cancer (TNBC) with BRCA deficiency due to primary and acquired resistance. Thus, there is a pressing need to develop alternative treatment regimens to target BRCA-mutated TNBC tumors that are resistant to PARP inhibition. Similar to PARP, poly(ADP-ribose) glycohydrolase (PARG) plays a role in DNA replication and repair. However, there are conflicting reports on the vulnerability of BRCA1-deficient tumor cells to PARG inhibition. This study aims to investigate the synergistically lethal effect of the PARG inhibitor COH34 and the ubiquitin-specific protease (USP) 14 inhibitor IU1-248 and the underlying mechanisms in BRCA1-mutant, PARP inhibitor-resistant TNBC cells. The cytotoxicity of PARG inhibition alone or in combination with USP14 inhibition in the BRCA-mutant, PARP inhibitor-resistant TNBC cell lines, HCC1937 and SUM149PT, was analyzed using cell viability and proliferation assays and flow cytometry. The molecular mechanisms underlying the synergistic effects of IU1-248 and COH34 were evaluated by immunofluorescence staining, DNA repair reporter assays and Western blot analysis. It was found that HCC1937 and SUM149PT cells exhibited moderate responsiveness to PARG inhibition alone. To the best of our knowledge, this research is the first to demonstrate that the combination of IU1-248 and COH34 produces synergistic effects against TNBC cells in the same setting. Mechanistically, the blockade of USP14 by IU1-248 was shown to increase DNA damage and promote error-prone non-homologous end joining (NHEJ), as evidenced by the accumulation of γH2AX and 53BP1 in the nucleus and the activation of a reporter assay. Additionally, it was demonstrated that the inhibition of NHEJ repair activity attenuates the synergistic effects of concomitant PARG and USP14 inhibition. IU1-248 promotes NHEJ repair through the downregulation of the expression of c-Myc. USP14 inhibition may be a plausible strategy for expanding the utility of PARG inhibitors in TNBC in BRCA-mutant, PARP inhibitor-resistant settings.

Effectiveness of mortar injection repair activity on an existing prestressed bridge girder

This paper reports the results of an experimental test performed on a prestressed reinforced concrete bridge girder, extracted from an existing bridge of the Italian highway network. The element exhibited cracks damage along the curved tendons of the prestressing system, probably due to the rainwater infiltration into the protecting duct. The experiment consists of a three-point bending test, where a point vertical load is located at mid-span and cyclically increased until bending collapse occurs. Before the test, the cracks pattern has been repaired by high-pressure injection of high-resistance mortar. The test results demonstrate the effectiveness of the mortar injection repair intervention.

A Preliminary Study on the Usage Behavior Pattern and Needs of the Ground Floor Entrance and Exit Section of a Detached House: Take Lǐ-Siǎng Community in Tainan as an Example to Discuss

“Arcade (Ding-a-ka)” has been discussed in the context of Taiwan’s indigenization and modernization. In the past research. The research results include: Historical aspect’s study of planning codes and spatial form for Arcades. And other street preservation issues etc. Our research found that on the one hand, “Arcade” and “Dwelling” are related. On the other hand, it is a public space that extends from environmental-behavior. This research paper discusses the environment-behavior of dwellers in urban growth boundary. The scope of this article is to use the method of architectural facade space’s case analysis and semi-structured interviews for residents. The purpose of the study is to discover the housing with different attributes on the architectural fa-cade space’s arcade, whether it will be influenced by the usage behavior and needs or it will arise the privatization of the public sphere elements. Discuss the community repair activities by the users of the architectural fa-cade space. The anticipated research contributions are understanding the disappearance of dwellers in history through “Arcade” and “Ding-a-ka” review. And how to get fieldwork information of public sphere through grounded theory (open coding) and environment-behavior. Access to a different kind of public domain in Taiwan community discussion than in the west theory.

Damage Types and Repair Techniques in Seljuk Period Stone Architectural Monuments: Konya Alaaddin Mosque

In order to determine the correct conservation and repair techniques for stone architectural monuments, it is necessary to determine the types of damage that occur in the stone. The determination of damage types is directly related to the factors that cause damage. In this study, the factors that cause deterioration in natural stones and the types of weathering were classified through literature research. Through the literature review, different repair techniques depending on the type of deterioration were examined. A field study was carried out based on the data obtained from the research conducted within the scope of the study. Alaaddin Mosque, one of the Seljuk period stone architectural monumental buildings located in Konya city centre and whose restoration works have been completed in recent years, was selected to be examined. In order to obtain information about the conservation and repair activities applied in the building, the archive of Konya Regional Directorate of Foundations, which carried out the restoration works, was utilized. The repairs applied to the building were documented by on-site inspection, observation and photography techniques. The observations made during the fieldwork draw attention to the deterioration of the stone materials after the repair activities. In this direction, the deterioration was photographed and classified using the data obtained from the literature. The factors causing the deterioration were analysed and discussed in the results section.

EVALUASI MANAJEMEN PEMELIHARAAN ARSITEKTUR, MEKANIKAL, DAN ELEKTRIKAL PADA GEDUNG HOTEL X DI KOTA PADANG

Based on the results of field inspections, damage to architectural, mechanical, and electrical components was found in several rooms of Hotel X in the city of Padang, West Sumatra, Indonesia. Lack of maintenance is one of the causes of damage to hotel building components. Good maintenance management can reduce repair activities that cost more due to injury. This study aims to evaluate the maintenance management of hotel buildings that have been carried out so far. In this study, researchers conducted surveys and interviews about hotel maintenance management. The survey and discussions focused on the hotel's Standard Operating Procedures (SOPs) for each component reviewed. After obtaining the hotel SOP, the researcher analyzed it by comparing the hotel SOP with the Minister of Public Works Regulation No.24/PRT/M/2008 as a standard in the implementation of building maintenance. From the results of the conformity calculation carried out, the conformity results in each component are architectural components with an average conformity result of 72.38%, mechanical parts with an average conformity result of 88.89%, and electrical components with an average conformity result of 77.78% of a maximum weight of 100%. This percentage of conformity weight shows that the hotel's maintenance management concerning the Ministerial Regulation is quite good. Still, to further optimize maintenance activities, it is necessary to plan better standard operating procedures, cost planning, and maintenance schedules to support implementing Hotel X building maintenance in the future.

The Medical Equipment Check and Repair Activity for The Community Service at Harmony Clinic

Abstract. Health is very important for society. People who are sick can seek treatment at the nearest health care facility. Health care facilities include hospitals, health centers and clinics. This service aims to improve medical equipment that will benefit patients who seek treatment at the clinic. The method used in this service is to use DPM (Digital Pressure Meter) equipment and a device from student namely bedside patient monitors used to calibrate the sphygmomanometer. This module is used to perform digital sphygmomanometer testing. The pulse oximetry calibration process was also carried out by measuring the BPM and the saturation level using the Prosim 8 tool. The tool that was repaired was a digital scale that was damaged due to the results of the scales not being appropriate. Then there is also the recording of the results of the calibration of the pulse oximetry and sphygmomanometer on the worksheet. The conclusion of this service activity is that this activity was attended by several lecturers, laboratory assistants, lab instructors and students who have carried out repairs to medical equipment and handed over grants in the form of tensimeters and thermoguns to representatives of the Harmony Clinic.

Penegakan Hukum Terhadap Pelaku Tindak Pidana Perusakan Kabel Bawah Laut Di Wilayah Hukum Polres Tanjung Jabung Barat Berdasarkan Uu No. 36 Tahun 1999 Tentang Telekomunikasi (Studi Kasus: Putusan Nomor 36/Pid.Sus/2023/PNKlt)

Underwater cables refer to all types of cables laid on the surface of the seabed, undersea cables have now developed into a Sea Cable Communication System (SKKL) thatare interconnected and mutually supportive. Underwater communication cables are cables laid under the sea to connect telecommunications between countries. The disconnection of the underwater cable communication network also occurred in the waters of the Pengabuan River, West Tanjung Jabung Regency. In this case the Tanjung Jabung Barat Resort Police, which is the jurisdiction of the incident, received a report and quickly carried out the law enforcement process, especially since this incident was the first time this had happened in the jurisdiction of the West Tanjung Jabung Police. As a result of the disconnection of the underwater cable network, it causes electromagnetic disturbances in the form of blackouts or interrupted communication networks. The purpose of this study is to understand and analyze how law enforcement is against the perpetrators of the criminal act of destroying undersea cables in the jurisdiction of the West Tanjung Jabung Police based on Law no. 36 of 1999 concerning Telecommunications (Case Study: Decision Number 36 /Pid.Sus /2023 /PN KLT), to understand and analyze the factors that become obstacles, and to understand and analyze the efforts made in overcoming existing obstacles. The research method used is empirical juridical. The results showed that in this case the Captain of the Ship, TB. DABO 103 is an element that is proven to have caused the interruption of the underwater fiber optic network in the waters of the Pengabuan Estuary, due to its negligence resulting in a violation of the provisions of Article 322 Jo Article 216 paragraph (1) of the Law of the Republic of Indonesia Number 17 of 2008 concerning Shipping whichreads"The skipper who carriesout repair activities, trial sailing, loading transfer activities at the port pool, delays, and loading and unloading of dangerous goods without the approval of the Syahbandar as referred to in Article 216 paragraph (1) shall be punished with imprisonment for a maximum of 6 (six) months or a fine 100,000,000.00 (one hundred million rupiah) at the most." For his negligence, the defendant was sentenced to imprisonment for 5 (five) months, because he was proven to have violated the provisions of Article 322 Jo Article 216 paragraph (1) of the Law of the Republic of Indonesia Number 17 of 2008 concerning Shipping, namely carrying out repair activities without the approval of Syahbandar. From the results of the research carried out, the suggestions given are that it is necessary to make ongoing appeals to captains to complete navigation tools in the form of BPI Pushidrosal Maps (Indonesian Seafarers' News) and the latest Marine Maps which serve to explain the latest situations and conditions in the waters and also which can explain the existence of the position of items under the sea including undersea cables so that similar incidents do not happen again.

Investigation of Effective Section Reduction in Low Carbon Steel during SMAW Welding

Welding, with its advantages of expedient execution and reduced weight, is a favored method for structural connections. However, it poses a significant risk, softening the steel and diminishing load-bearing capacity, underscoring the importance of accurate estimation. The need for precision is paramount, as critical infrastructure must remain operational not only during disasters but also during repair and maintenance activities. To address this challenge, this research introduces an approach to estimate the extent of capacity reduction resulting from welding, providing engineers with valuable insights for maintaining these critical systems structural integrity and functionality. The study examined low-carbon steel with various thicknesses, focusing on Heat Affected Zone (HAZ) width calculations and Abaqus simulations. Welding was performed at a speed of 1.67 cm/s with a 5 mm element increment. This research aimed to investigate the impact of welding parameters on low-carbon steel, particularly concerning HAZ measurements. A 4 mm-thick plate generated a 38.73 mm affected zone, while simulations with 5 mm to 12 mm thicknesses produced progressively narrower affected zones. Results demonstrated that steel plate thickness significantly influences the affected zone width, with thicker plates yielding narrower affected zones. The study examined low carbon steel with a 4 mm thickness, focusing on Heat Affected Zone (HAZ) width calculations and Abaqus simulations. Welding was performed at a speed of 1.67 cm/s with a 5 mm element increment. The research aimed to investigate the impact of welding parameters on low carbon steel, particularly concerning HAZ measurements. Results demonstrated that steel plate thickness significantly influences the affected zone width, with thicker plates yielding narrower affected zones. A 4 mm-thick plate generated a 38.73 mm affected zone, while simulations with 5 mm to 12 mm thicknesses produced progressively narrower affected zones.

Development and characterization of antibacterial 3D porous hydroxyapatite-gelatin-PVA scaffolds containing zinc oxide nanoparticles

There is still a need to develop hydroxyapatite (HAp)/gelatin-based porous scaffolds to provide a hybrid system with structural and biochemical properties equivalent to those of bone. Here, we fabricated and characterized 3D hybrid scaffolds composed of HAp nanoparticles synthesized in situ in gelatin and PVA solutions and loaded with combustionally synthesized (10 wt%) zinc oxide nanoparticles (ZnO NPs) to ensure their homogeneous embedding in the polymer matrices. The phase analysis, composition, morphological and microstructural properties of ZnO NPs and freeze-dried hybrid scaffolds were studied. The compressive strength, porosity, swelling capacity, degradation rate, and antibacterial activity of the hybrid scaffolds were measured. The fabricated 3D scaffolds showed high porosity of up to 78 % with a pore size of about 50–300 μm, good mechanical strength in the range of about 55 kPa, high swelling capacity of up to 505 %, and long-term degradation rate of about 22–25 % for up to 35 days. ZnO NPs have a pure phase and a quasi-spherical shape with a size of about 78 ± 25 nm structure and there are no significant differences between the physicochemical properties of ZnO-free scaffolds and ZnO-loaded scaffolds. Incorporation of ZnO NPs into the scaffolds enhanced their antibacterial response against pathogenic Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). This work provides advanced 3D porous hybrid bone scaffolds with favorable mechanical performance and antibacterial activity for bone repair and regeneration.