Low Molecular Weight Research Articles

A National-Scale Study of Polycyclic Aromatic Hydrocarbons in Surface Water: Levels, Sources, and Carcinogenic Risk

Elucidating pollution characteristics of polycyclic aromatic hydrocarbons (PAHs) in water and assessing the associated carcinogenic risks is crucial for improving public health. PAHs in the surface water of seven main river basins across China, compiled from 95 studies from 2004 to 2022, were used to investigate geographic variations of occurrence, source, and carcinogenic risk. Total PAH concentrations exhibited substantial geographic distributions ranging from 300 to 7552 ng·L−1. Low molecular weight PAHs predominated, showing three-ring PAHs abundant in the north, while two-ring PAHs dominated in the south due to distinctions regarding energy consumption. The northern basins exhibited higher concentrations of PAHs than the southern owing to the synergistic impacts of low temperature, increased energy consumption, and higher industrial activities. Coal combustion and industrial emissions were the primary contributors in the northern basins, accounting for 23–44% and 20–38%, respectively, which were associated with pollutants released from heavy industries and space heating during cold periods. In contrast, vehicle exhaust emissions and petroleum leakage from river transport constituted the principal sources in the relatively economically developed southern basins, accounting for 24–35% and 31–57%, respectively. A lifetime carcinogenic risk model revealed that the highest health risks existed in adults, followed by adolescents and children. Toxic concentrations of BaP and the daily intake of water directly enhanced the PAHs’ carcinogenic risks, while body weight featured negative correlations with the risks.

Growing Macrophages Regulate High Rates of Solute Flux by Pinocytosis.

Murine macrophages growing in response to colony-stimulating factor-1 (CSF1) require pinocytosis. High rates of solute influx and accumulation by pinocytosis are regulated by CSF1 and leucine. Low molecular weight products of protein hydrolysis in lysosomes recycle efficiently from the cells.

A Polyvinyl Alcohol (PVA)-Based Phantom for Prostate Cancer Detection Using Multiparametric Ultrasound: A Validation Study

Multiparametric ultrasound (mpUS) enhances prostate cancer (PCa) diagnosis by using multiple imaging modalities. Tissue-mimicking materials (TMM) phantoms, favoured over animal models for ethical and consistency reasons, were created using polyvinyl alcohol (PVA) with varying molecular weights (Mw). Methods: Four PVA samples, varying in Mw with constant concertation, were mixed with glycerol, silicon carbide (SiC), and aluminium oxide (Al2O3). Phantoms with varying depth and inclusion sizes were created and tested using shear-wave elastography (SWE). An mpUS phantom was developed to mimic prostate tissue, including isoechoic and hypoechoic inclusions and vessels. The phantom was scanned using supersonic ultrasound, strain elastography, and Doppler ultrasound. Validation was performed using radical prostatectomy data and shear-wave elastography. Results: The acoustic properties varied with enhancers like glycerol and Al2O3. Low Mw PVA samples had a speed of sound ranging from 1547.50 ± 2 to 1553.70 ± 2.2 m/s and attenuation of 0.61 ± 0.062 to 0.63 ± 0.05 dB/cm/MHz. High Mw PVA samples ranged from 1555 ± 2.82 to 1566 ± 4.5 m/s and 0.71 ± 0.02 to 0.73 ± 0.046 dB/cm/MHz. Young’s modulus ranged from 11 ± 2 to 82.3 ± 0.5 kPa across 1 to 10 freeze-thaw cycles. Inclusion size, depth, and interaction statistically affect the SWE measurements with p-value = 0.056327, p-value = 8.0039 × 10−8, and p-value = 0.057089, respectively. SWE showed isoechoic inclusions, prostate tissue, and surrounding tissue only. The Doppler velocity was measured in three different inner diameters. Conclusion: PVA mixed with enhancer materials creates an mpUS phantom with properties that mimic normal and abnormal prostate tissue, blood vessels, and soft tissue, facilitating advanced diagnostic training and validation.

Phenylethynyl-Terminated Imide Oligomer-Based Thermoset Resins.

Phenylethynyl-terminated imide (PETI) oligomers are highly valued for their diverse applications in films, moldings, adhesives, and composite material matrices. PETIs can be synthesized at varying molecular weights, enabling the fine-tuning of their properties to meet specific application requirements. Upon thermal curing, these oligomers form super-rigid network structures that enhance solvent resistance, increase glass-transition temperatures, and improve elastic moduli. Their low molecular weights and melt viscosities further facilitate processing, making them particularly suitable for composites and adhesive bonding. This review examines recent advancements in developing ultra-high-temperature PETIs, focusing on their structure-processing-properties relationships. It begins with an overview of the historical background and key physicochemical characteristics of PETIs, followed by a detailed discussion of PETIs synthesized from monomers featuring noncoplanar configurations (including kink and cardo structures), fluorinated groups, flexible linkages, and liquid crystalline mesogenic structures. The review concludes by addressing current challenges in this research field and exploring potential future directions.

Zn(II)-based mechanically flexible metallosupramolecular network: Investigating rheology, morphology, anti-bacterial effect and semiconducting device performances

Synthesis of supramolecular Zn(II)-metallogel of succinic acid with N,N′-dimethyl formamide (DMF) solvent has been explored in this present study. Succinic acid is used as a low molecular weight gelator (LMWG) and DMF acts as a metallogel-immobilized solvent-media. Mechanical flexibility, viscous, and elastic behaviours of the metallogel are characterized by exhaustive rheological experiments. Different rheological parameters like storage modulus (G′) and loss modulus (G″) are evaluated for certain regions of shear strain and angular frequency. The morphological decoration of xerogel material obtained from Zn(II)-based metallosupramolecular gel (i.e., Zn-Succinic) has been visualized through field emission scanning electron microscope (FESEM). Energy dispersive X-ray analysis (EDX) verifies the active involvement of metallogel-forming chemical constituents. The flexible metallosupramolecular scaffold-construction strategy has been unveiled through infrared spectroscopic data and ESI-Mass investigations. The antibacterial potency of Zn(II)-directed metallogel has also been verified against several Gram-positive bacteria (i.e., Bacillus cereus (ATCC 13061), Bacillus subtilis (MTCC 121), Listeria monocytogenes (MTCC 657), Staphylococcus aureus (MTCC 96)), and two Gram-negative bacterial strains (i.e., Salmonella typhimurium (MTCC 98) and Escherichia coli (MTCC 1667)). Even, Zn-Succinic metallogel exhibits Schottky diode behaviour with a significant non-linear rectifying nature in I-V curve, proving the semiconducting diode features with electrical parameters.

Advancing Anticancer Drug Discovery: Leveraging Metabolomics and Machine Learning for Mode of Action Prediction by Pattern Recognition.

A bottleneck in the development of new anti-cancer drugs is the recognition of their mode of action (MoA). Metabolomics combined with machine learning allowed to predict MoAs of novel anti-proliferative drug candidates, focusing on human prostate cancer cells (PC-3). As proof of concept, 38 drugs are studied with known effects on 16 key processes of cancer metabolism, profiling low molecular weight intermediates of the central carbon and cellular energy metabolism (CCEM) by LC-MS/MS. These metabolic patterns unveiled distinct MoAs, enabling accurate MoA predictions for novel agents by machine learning. The transferability of MoA predictions based on PC-3 cell treatments is validated with two other cancer cell models, i.e., breast cancer and Ewing's sarcoma, and show that correct MoA predictions for alternative cancer cells are possible, but still at some expense of prediction quality. Furthermore, metabolic profiles of treated cells yield insights into intracellular processes, exemplified for drugs inducing different types of mitochondrial dysfunction. Specifically, it is predicted that pentacyclic triterpenes inhibit oxidative phosphorylation and affect phospholipid biosynthesis, as confirmed by respiration parameters, lipidomics, and molecular docking. Using biochemical insights from individual drug treatments, this approach offers new opportunities, including the optimization of combinatorial drug applications.

Effect, Fate and Remediation of Pharmaceuticals and Personal Care Products (PPCPs) during Anaerobic Sludge Treatment: A Review.

Biomass energy recovery from sewage sludge through anaerobic treatment is vital for environmental sustainability and a circular economy. However, large amounts of pharmaceutical and personal care products (PPCPs) remain in sludge, and their interactions with microbes and enzymes would affect resource recovery. This article reviews the effects and mechanisms of PPCPs on anaerobic sludge treatment. Most PPCPs posed adverse impacts on methane production, while certain low-toxicity PPCPs could stimulate volatile fatty acids and biohydrogen accumulation. Changes in the microbial community structure and functional enzyme bioactivities were also summarized with PPCPs exposure. Notably, PPCPs such as carbamazepine could bind with the active sites of the enzyme and induce microbial stress responses. The fate of various PPCPs during anaerobic sludge treatment indicated that PPCPs featuring electron-donating groups (e.g., ·-NH2 and ·-OH), hydrophilicity, and low molecular weight were more susceptible to microbial utilization. Key biodegrading enzymes (e.g., cytochrome P450 and amidase) were crucial for PPCP degradation, although several PPCPs remain refractory to biotransformation. Therefore, remediation technologies including physical pretreatment, chemicals, bioaugmentation, and their combinations for enhancing PPCPs degradation were outlined. Among these strategies, advanced oxidation processes and combined strategies effectively removed complex and refractory PPCPs mainly by generating free radicals, providing recommendations for improving sludge detoxification.

Ultrathin membranes comprising polymers of intrinsic microporosity oligomers for high-performance organic solvent nanofiltration

Microporous organic polymers (MOPs) featuring chemically rigid backbones and permanent micropores are desirable for fabricating molecular selective membranes towards organics separation. However, coordinating facile film processing with high micropore persistence remains a challenge. In this paper, a low molecular weight polymers of intrinsic microporosity was rationally designed by precisely controlling the stoichiometric equilibrium of polymerization monomer. The polymers of intrinsic microporosity oligomers combine rigid and contorted structures with the aqueous solution processability, promoting the formation of 25-nm-thick polyacrylamide nanofilms with enhanced microporosity via support-free interfacial polymerization (SFIP). The resulting composite membranes have superior retention of small molecular solutes and high nonpolar and polar solvent permeances. Experiment and simulation results show that their excellent separation performance is due to substantially open and interconnected microporosity formed in the polymer networks based on rigid and contorted diamines as well as reduced film thickness. This study provides a new sight for using MOPs to construct high-microporosity membranes for precise and rapid molecular sieving.

Fractionation of lignin and fermentable sugars from wheat straw using an alkaline hydrogen peroxide/pentanol biphasic pretreatment

To breakthrough the delignification saturation point (DSP) of alkaline hydrogen peroxide (AHP) pretreatment, a biphasic AHP/pentanol (AHPP) pretreatment was proposed in this work. The temperature and H2O2 concentration were evaluated. Under the optimal conditions (110 °C, 2 h, 4 % H2O2), 70.73 % of lignin was removed, which was increased by 11.65 % than the traditional AHP pretreatment, indicating successful overcoming of the DSP by adding pentanol. 85.74 % and 88.62 % of glucan and xylan digestibility were achieved, respectively, which increased by 7.41 % and 5.87 % as compared to AHP pretreatment. Furthermore, the lignin extracted from the organic phase accounted for 38.51 % of the delignification, and it had a low molecular weight, effectively preserving the β-O-4 bonds. Finally, satisfied pentanol recovery (77.91 %) and delignification (57.19 %) along with excellent glucan (76.11 %) and xylan (77.52 %) digestibility were reached after fourth recycling of AHPP pretreatment. Therefore, AHPP pretreatment was a promising method for biomass valorization within biorefinery concept.

Leucettinib-21, a DYRK1A Kinase Inhibitor as Clinical Drug Candidate for Alzheimer's Disease and Down Syndrome.

Alzheimer's disease (AD) and Down syndrome (DS) share a common therapeutic target, the dual-specificity, tyrosine phosphorylation activated kinase 1A (DYRK1A). Abnormally active DYRK1A is responsible for cognitive disorders (memory, learning, spatial localization) observed in both conditions. In DS, DYRK1A is overexpressed due to the presence of the DYRK1A gene on chromosome 21. In AD, calcium-activated calpains cleave full-length DYRK1A (FL-DYRK1A) into a more stable and more active, low molecular weight, kinase (LMW-DYRK1A). Genetic and pharmacological experiments carried out with animal models of AD and DS strongly support the idea that pharmacological inhibitors of DYRK1A might be able to correct memory/learning disorders in people with AD and DS. Starting from a marine sponge natural product, Leucettamine B, Perha Pharmaceuticals has optimized, through classical medicinal chemistry, and extensively characterized a small molecule drug candidate, Leucettinib-21. Regulatory preclinical safety studies in rats and minipigs have been completed and formulation of Leucettinib-21 has been optimized as immediate-release tablets. Leucettinib-21 is now undergoing a phase 1 clinical trial (120 participants, including 12 adults with DS and 12 patients with AD). The therapeutic potential of DYRK1A inhibitors in AD and DS is presented.

Optimizing Electron‐Beam Photothermal Pyrolysis Parameters for Enhanced Molecular Biodegradability of Polyvinyl Chloride Plastics

AbstractPolyvinyl chloride (PVC), a synthetic plastic notable for harmful emissions during deterioration, has potential to be molecularly adjusted by photo‐oxidative ultraviolet degradation. This research investigates the influence of electron beam irradiation and near‐infrared photothermal treatment utilizing gold nanoparticles to establish the optimized molecular weight and beam time exposure for biodegradable PVC properties while maintaining a minimum tensile strength as measured through the ratio of peak tension force by cross sectional area. PVC powder samples with number‐average molecular weights ranging from 20.0 to 90.0 kDa and varying exposure times of a 100 kGy electron beam from 80 to 115 ms are employed for the study. Outcomes from PVC irradiation reveal the optimal parameters for inducing biodegradability in samples: an e‐beam exposure duration of 95 ms applied to PVC powder with a sample molecular weight of 20.0 kDa. Analysis of the ratio of number average molecular weight and weight average molecular weight demonstrates that shorter irradiation durations result in lower molecular weights and molecular weight is directly proportional to Tg and crystallinity. Future work aims to scale up the procedure to industrial applications and investigate the treatment's applicability to a variety of thermoplastics.

Comprehensive chromatographic profiling and structural analysis of key anticoagulant components in enoxaparin

Heparin is the most widely used anticoagulant in clinical practice, with enoxaparin being one of the most important low molecular weight heparins (LMWHs). In this study, an antithrombin III (ATIII) affinity column was used. Enoxaparin and its oligosaccharides of varying sizes, prepared using preparative size exclusion chromatography (SEC), were fractionated through the ATIII affinity column. The different affinity fractions from each oligosaccharide size were profiled using strong anion exchange (SAX) chromatography. Each peak was automatically transferred to an SEC column for desalting prior to mass spectrometry (MS) analysis, which enabled structural identification using a multiple heart-cut (MHC) 2D LC-MS system (SAX-SEC-MS). The high-affinity fraction from enoxaparin was further analyzed using the MHC 2D LC system (SEC-SAX). SAX profiles of the high-affinity oligosaccharides, prepared by both size and affinity fractionation, were consistent with those obtained by direct SEC-SAX analysis. The possible sequences of several high-affinity hexasaccharides and the domain compositions of high-affinity octa- and decasaccharides in enoxaparin were further elucidated by disaccharide analysis after manual collection of the oligosaccharides. This work advances the understanding of enoxaparin's structural features and offers a potential approach to improve the quality of enoxaparin, as well as to identify key structural motifs in heparin/LMWHs that contribute to protein binding.

Meloxicam-amino acids salts/ion pair complexes with advanced solubility, dissolution, and gastric safety

Amino acids have attracted attention as a potential functional excipient for optimizing biopharmaceutics characteristics of poorly soluble drugs. The amino acids are a diverse class with many functional groups, natural compounds, biocompatible and low molecular weight substances. Two amino acids serine and arginine were investigated with meloxicam. Meloxicam has extremely low solubility; being NSAIDs, gastric upset and ulcer are common side effects. Solid dispersions were produced by precipitation and physical mixing techniques. The produced combinations underwent in vitro dissolution, docking, DSC, FTIR, XRD, solubility and gastric ulcer formation studies. Docking indicated formation of ion pair/salt between the basic amino acid arginine and meloxicam. Both solubility and dissolution rates were increased by up to 3000- and 12-fold, respectively. DSC, FTIR an XRD supported these findings. Rats treated with meloxicam showed loss of surface gastric epithelium integrity and ulceration. The animal group received meloxicam: arginine showed intact gastric mucosa with the surface epithelium and gastric glands well organized and nearly similar to the untreated control. Arginine with the guanidine group that was capable of preserving gastric mucosa after repeated administration for 10 days. This study highlighted the role of arginine as a functional excipient that did not only improve solubility and dissolution rates but ameliorated the long-standing gastric side effects attributed to meloxicam.

COVID-19-induced extracorporeal circulation coagulation during continuous renal replacement therapy: A cross-sectional study.

After the control policies of the COVID-19 epidemic were lifted in China from December 5th, 2022, there was an increase in the demand for hemodialysis and continuous renal replacement therapy (CRRT) at our center, and patients experienced hypercoagulable blood states more frequently. This study aimed to investigate the effect of COVID-19 on extracorporeal coagulation during CRRT. All CRRT records were gathered from the Hemodialysis Center at our hospital from December 5th, 2022 to February 4th, 2023, and analyzed the incidence and risk factors associated with extracorporeal coagulation. COVID-19 substantially increased the likelihood of extracorporeal coagulation during CRRT. Venous pressure and transmembrane pressure were proportional to the severity of extracorporeal coagulation. Additionally, non-tunnel type conduit vascular access, and acute kidney injury had a positive correlation with the severity of coagulation. Blood tests demonstrated that COVID-19 altered 4 coagulation indices. Moreover, mitigation of coagulation can be achieved through increasing the dosage of low molecular weight heparin and administering regional citrate anticoagulation. Patients who fail anticoagulation may be switched to peritoneal dialysis. In conclusion, COVID-19 poses a heightened risk of extracorporeal coagulation during CRRT. This study underscores the importance of anticoagulant treatment in CRRT for infected patients with kidney failure and holds significant implications for clinical practice. In future, the epidemics of COVID-19 or any other pandemic, the metrics in this study can be referenced to determine coagulation risk, as well as relevant therapeutic practices may be considered.

Effect of Low Molecular Weight Heparin Calcium on Prevention of Lower Limb Deep Venous Thrombosis in Oral Cancer Patients With Anterolateral Thigh Flap Reconstruction.

This study aimed to evaluate the effect of low molecular weight heparin calcium (LMWH-Ca) on the prevention of deep venous thrombosis (DVT) in patients with anterolateral thigh (ALT) flap reconstruction. In total, 1001 patients with oral cancer who underwent ALT flap reconstruction were recruited. Based on the postoperative use of LMWH-Ca, the patients were divided into case (n = 633) and control groups (n = 368). The incidence of postoperative DVT was compared between groups. There was no significant difference in DVT incidence between the two groups. Among patients older than 60 years, the incidence of lower limb DVT in the case group (0.813%) was significantly lower than that in the control group (8.108%, p = 0.012). The postoperative use of LMWH in oral cancer patients with ALT flap transfer does not prevent the development of lower limb DVT. However, patients older than 60 years old benefited from the postoperative use of LMWH-Ca.

Een ongebruikelijke oorzaak van een hoge digestieve bloeding: amyloïdose van de maag

An unusual cause of major upper digestive bleeding: gastric amyloidosis Amyloidosis is a systemic disease that may target the gastrointestinal tract. The disease is caused by the extracellular tissue deposition of fibrils composed of low-molecular weight subunits of a variety of proteins. Amyloidosis may encompass multiple presentations and symptoms, being a challenge for both the diagnosis and the treatment. Gastrointestinal amyloidosis can cause bleeding, malabsorption, protein-losing enteropathy and dysmotility. The authors describe the case of a 71-year-old patient with persisting epigastric discomfort. The initial gastroscopy revealed ulcerative gastritis. Biopsies turned out to be Helicobacter pylori negative. There were no signs of malignancy either. An additional gastroscopy because of discomfort confirmed ulcerative gastritis. Anatomopathological examination of new biopsies revealed amyloidosis of the stomach. Additional examinations (including an echocardiography, a PET CT scan and a colonoscopy with rectal biopsies and Congored staining) did not confirm other organs to be involved in the amyloidosis. The patient was readmitted later because of a major upper digestive bleeding due to persisting gastric ulcerations. A partial distal gastrectomy turned out to be inevitable. Anatomopathological examination of the stomach confirmed non-AA amyloidosis of the stomach. Additionally, a short overview of amyloidosis with special attention to the impact of the disease in the gastrointestinal tractus is presented.

Use of aqueous polyvinyl alcohol in binder jetting of Inconel 718

Binders used in binder jetting often pose health and environmental risks during processing and post processing operations. The print-heads which are used to deposit binder selectively on the feedstock are prone to clogging, despite the trend of print-heads being highly customised to suit different kinds of binders. These factors often hide the advantages of binder jetting as an additive manufacturing process, especially its scalability and its faster printing rates in comparison to powder bed fusion methods. The work presented here takes a step back and focuses on the development of an aqueous, polyvinyl alcohol (PVA)-based liquid binder that is easy to manufacture and store, safe to handle, and can be reliably jetted to print parts. The feedstock considered was Inconel 718, a nickel-based super alloy which can be effectively processed by binder jetting without niobium segregation. PVA was added to the Inconel 718 powder in dry, granular form to manufacture a modified feedstock. The study also investigated the role of molecular weight of the PVA used, sintering environments and post-processing methods like hot isostatic pressing (HIP) on process responses like part densification, tensile strength, and hardness. Three different types of PVA were chosen which had molecular weights 10,000 g/mol (low molecular weight or LMW), 26,000 g/mol (medium molecular weight or MMW), and 84,000 g/mol (high molecular weight or HMW). The compatibility of the liquid, aqueous PVA-based binders with virgin Inconel 718 was examined by measuring the contact angle. The liquid, aqueous binder having MMW PVA reported better wetting with the Inconel 718 powder with a wetting angle of 26.6 which was lower than the wetting angle of 42.4°, seen in case of a commercial resin-based binder. The green strength reported by the MMW PVA liquid binder was 220 kPa which was higher than the other two PVA-based liquid binders. Green parts, upon successful printing, were sintered at 1260 °C. It was observed that a part printed using MMW PVA had a densification of 96.16% when sintered in 99.98% by volume argon gas, which increased to 98.96% after undergoing HIP. The same part reported a densification of 88.69% when sintered in a 95% by volume N2 and 5% by volume H2 gaseous environment, which was later attributed to the uptake of nitrogen by the chromium present in Inconel 718, which prevented necking between particles. Tensile specimens printed using MMW PVA, sintered in a 99.98% argon environment, showed the highest ultimate tensile strength of 220 MPa, which increased to 1010 MPa after the HIP process, which can be compared to commercially available Inconel 718.

Fouling of Reverse Osmosis (RO) and Nanofiltration (NF) Membranes by Low Molecular Weight Organic Compounds (LMWOCs), Part 1: Fundamentals and Mechanism.

Reverse osmosis (RO) and nanofiltration (NF) are ubiquitous technologies in modern water treatment, finding applications across various sectors. However, the availability of high-quality water suitable for RO/NF feed is diminishing due to droughts caused by global warming, increasing demand, and water pollution. As concerns grow over the depletion of precious freshwater resources, a global movement is gaining momentum to utilize previously overlooked or challenging water sources, collectively known as "marginal water". Fouling is a serious concern when treating marginal water. In RO/NF, biofouling, organic and colloidal fouling, and scaling are particularly problematic. Of these, organic fouling, along with biofouling, has been considered difficult to manage. The major organic foulants studied are natural organic matter (NOM) for surface water and groundwater and effluent organic matter (EfOM) for municipal wastewater reuse. Polymeric substances such as sodium alginate, humic acid, and proteins have been used as model substances of EfOM. Fouling by low molecular weight organic compounds (LMWOCs) such as surfactants, phenolics, and plasticizers is known, but there have been few comprehensive reports. This review aims to shed light on fouling behavior by LMWOCs and its mechanism. LMWOC foulants reported so far are summarized, and the role of LMWOCs is also outlined for other polymeric membranes, e.g., UF, gas separation membranes, etc. Regarding the mechanism of fouling, it is explained that the fouling is caused by the strong interaction between LMWOC and the membrane, which causes the water permeation to be hindered by LMWOCs adsorbed on the membrane surface (surface fouling) and sorbed inside the membrane pores (internal fouling). Adsorption amounts and flow loss caused by the LMWOC fouling were well correlated with the octanol-water partition coefficient (log P). In part 2, countermeasures to solve this problem and applications using the LMWOCs will be outlined.

Dynamic behavior of melt electrospinning of blended polypropylene

Melt electrospinning is a promising process for fiber production without the need for solvents and with potential applications in various fields. In this study, we investigated the dynamic behavior of melt electrospinning under different blending ratios and process conditions. We used high melt flow index polypropylene and low molecular weight polypropylene, which were blended to lower the melt viscosity, and fibers were successfully manufactured through the melt electrospinning process. The effects of blending ratio and applied voltage on jet and drop formation, as well as fiber morphology, were examined. The results showed that blending low-molecular-weight polypropylene significantly influenced the jet and drop areas, leading to fluctuations in jet morphology. The size of the applied high voltage also had a high effect on the fiber diameter. Additionally, the viscosity reduction achieved through blending allowed for continuous jet formation and improved fiber production. These results provide valuable insights into controlling the process parameters and blending ratios in melt electrospinning, enabling the establishment of stable electrospinning conditions and precise control of fiber diameter.

The Effect of Acetic Acid as a Solvent on the Structure and Properties of Poly(3-hydroxybutyrate)-Based Dried Gels.

Poly(3-hydroxybutyrate) (PHB) is a microbially derived polyhydroxyalkanoate that is widely used in biomedical applications. In this study, we investigated the use of acetic acid (aa) as an alternative environmentally friendly solvent for the preparation of gels from PHB (PHB aa) and compared their characteristics with PHB products dissolved in chloroform (PHB chl) using such methods as DSC, FTIR, SEM, rheometry, biodegradation, and cytocompatibility assay. A slight decrease in the degree of the crystallinity of the PHB from 61% to 50.8% was found when the acetic acid was used. This resulted in a greater mass loss for the PHB aa (11%) during enzymatic degradation over 180 days. Gels prepared from PHB in the different solvents showed differences in the microstructure and porosity of the samples, which affected their viscoelastic properties. The storage modulus (G') for the PHB aa gels was higher by 35% compared to that for the PHB chl, and Young's modulus in compression was 101.5 and 41.3 kPa for the PHB aa and PHB chl, respectively. The porosity of the PHB aa was 97.7%, which was 5.2% higher than that for the PHB chl. The presence of low molecular weight polymers in the PHB aa had an effect on mesenchymal stem cells' viability, expressed as a threefold increase in the number of attached cells after 7 days of incubation compared to the PHB chl. Thus, the proposed method of PHB-based materials' preparation is a promising, more environmentally friendly analog of the extensively used method of preparation from chloroform.