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Thе pаpеr hаs invеstigаtеd flоссulаtiоn саpасitу оf pоlуhеxаmеthуlеnе guаnidinе hуdrосhlоridе during jоint trеаtmеnt with аluminum sulfаtе оf thе Nаrin аnd Sirdаrуа Rivеr wаtеr in thе spring pеriоd. It hаs bееn shоwn thаt аdditivеs 1–5 mg/dm 3 о f thе mаttеr undеr studу during соаgulаtiоn trеаt-mеnt оf thе rivеr wаtеrs imprоvеs thе prосеss оf thеir сlаrifiсаtiоn, inсrеаsеs thе filtrаtе quаlitу in tеrms оf mаin indiсаtоrs аnd mаkеs it pоssiblе tо rеduсе bу 10–20 mg/dm 3 thе dоsе оf thе соаgulаnt. А prоnоunсеd flоссulаtiоn еffесt mаnifеsts itsеlf whеn trеаting thе wаtеrs in quеstiоn bу thе dоsеs оf а pоlуmеr prеpаrаtiоn rеspесtivеlу 3–5 аnd 2–3 mg/dm 3 . Pоlуhеxаmеthуlеnе guаnidinе (withоut а соаgulаnt) еnsurеs а stаndаrdizеd quаlitу оf thе filtrаtе in tеrms оf соlоr аnd turbiditу оnlу whеn trеаting wеаklу stаinеd wаtеr оf thе Sirdаrуа Rivеr. It hаs bееn fоund thаt ≥ 99% оf pоlуhеxаmеthуlеnе guаnidinе is rеtаinеd bу thе mеdium оf а sаnd filtеr.

The focus of this study was to compare the yield and characteristics of chitosan produced from different sequences of treatment for deproteination, demineralization and deacetylation. In Process 1, deproteination occurred in the first step followed by demineralization and deacetylation. While Process 2 was started with demineralization step and followed by deproteination and deacetylation. The results show that the percentage yield of chitosan was slightly higher when Process 2 was adopted with 22.22 %. However, the process produced chitosan with lower degree of deacetylation and solubility with high ash content, which were 76.47 %, 37.79 % and 2.67 %, respectively. While, when Process 1 was carried out, the degree of deacetylation of chitosan, solubility and ash content were improved to 91.26 %, 100 % and 0.38 %, respectively, with lower yield of 19.01 %. Therefore, this study suggests the extraction process should be performed by carrying out deproteination step before demineralization and deacetylation (Process 1) to produce a good quality of chitosan.

The increasing demand for a whiter smile has resulted in an increased popularity for tooth whitening procedures. The most classic hydrogen peroxide-based whitening agents are effective, but can lead to enamel demineralization, gingival irritation, or cytotoxicity. Furthermore, these techniques are excessively time-consuming. Here, we report a nondestructive, harmless and convenient tooth whitening strategy based on a piezo-catalysis effect realized by replacement of abrasives traditionally used in toothpaste with piezoelectric particles. Degradation of organic dyes via piezo-catalysis of BaTiO 3 (BTO) nanoparticles was performed under ultrasonic vibration to simulate daily tooth brushing. Teeth stained with black tea, blueberry juice, wine or a combination thereof can be notably whitened by the poled BTO turbid liquid after vibration for 3 h. A similar treatment using unpoled or cubic BTO show negligible tooth whitening effect. Furthermore, the BTO nanoparticle-based piezo-catalysis tooth whitening procedure exhibits remarkably less damage to both enamel and biological cells. Tooth whitening has attracted significant interest; however, most techniques are potentially destructive. Here, the authors model the replacement of standard abrasives in toothpaste with piezoelectric particles for catalytic degradation of organic stains and report less damage than hydrogen peroxide treatment.

Shrimp is one of Indonesia’s main export sectors, contributing to increasing foreign exchange incomes. Shrimp shells contain an essential compound, chitosan, commonly utilized in cosmetic, food, and textile industries. Here, chitosan was extracted from the shrimp shell waste by drying the shells and crushing them to obtain a fine powder. Then, the powder was isolated to attain optimal chitosan content through four stages: deproteinization, demineralization, depigmentation, and deacetylation. X-ray diffraction (XRD) characterization showed that the prepared chitosan demonstrated a sharp peak at 2θ = 19.54°. The value is close to Merck’s chitosan factory data, indicating the presence of chitosan. Scanning Electron Microscope-Energy Dispersive X-ray (SEM-EDX) testing exhibited a homogeneous morphology of the prepared shrimp shell powder and primary elemental compositions, including O and C with > 40%. Fourier Transform Infra-Red (FTIR) testing showed OH and NH2 functional groups, the main elements of chitosan. Based on the characterization results using a Particle Size Analyzer (PSA) with the light scattering technique results show that particle size is 44 nm. According to the characterization results, this study successfully synthesized chitosan from the shrimp shell waste.

Tooth decay (dental caries) is a widespread human disease caused by microbial biofilms. Streptococcus mutans, a biofilm-former, has been consistently associated with severe childhood caries; however, how this bacterium is spatially organized with other micro-organisms in the oral cavity to promote disease remains unknown. Using intact biofilms formed on teeth of toddlers affected by caries, we discovered a unique 3D rotund-shaped architecture composed of multiple species precisely arranged in a corona-like structure with an inner core of S. mutans encompassed by outer layers of other bacteria. This architecture creates localized regions of acidic pH and acute enamel demineralization (caries) in a mixed-species biofilm model on human teeth, suggesting this highly ordered community as the causative agent. Notably, the construction of this architecture was found to be an active process initiated by production of an extracellular scaffold by S. mutans that assembles the corona cell arrangement, encapsulating the pathogen core. In addition, this spatial patterning creates a protective barrier against antimicrobials while increasing bacterial acid fitness associated with the disease-causing state. Our data reveal a precise biogeography in a polymicrobial community associated with human caries that can modulate the pathogen positioning and virulence potential in situ, indicating that micron-scale spatial structure of the microbiome may mediate the function and outcome of host–pathogen interactions.

Candida albicans has been detected in root carious lesions. The current study aimed to explore the action of this fungal species on the microbial ecology and the pathogenesis of root caries. Here, by analyzing C. albicans in supragingival dental plaque collected from root carious lesions and sound root surfaces of root-caries subjects as well as caries-free individuals, we observed significantly increased colonization of C. albicans in root carious lesions. Further in vitro and animal studies showed that C. albicans colonization increased the cariogenicity of oral biofilm by altering its microbial ecology, leading to a polymicrobial biofilm with enhanced acidogenicity, and consequently exacerbated tooth demineralization and carious lesion severity. More importantly, we demonstrated that the cariogenicity-promoting activity of C. albicans was dependent on PHR2 . Deletion of PHR2 restored microbial equilibrium and led to a less cariogenic biofilm as demonstrated by in vitro artificial caries model or in vivo root-caries rat model. Our data indicate the critical role of C. albicans infection in the occurrence of root caries. PHR2 is the major factor that determines the ecological impact and caries-promoting activity of C. albicans in a mixed microbial consortium.

To address the limitations of conventional dentin adhesives, including inadequate sealing depth, poor long-term stability, and secondary caries formation, this study developed an etch-and-rinse adhesive incorporating amorphous calcium phosphate (ACP) nanoparticles for deep tubular occlusion. Serine-stabilized ACP nanoparticles were synthesized. The adhesive matrix contained 5 wt% ACP nanoparticles in pentaerythritol tetra-3-mercaptopropionate (PETMP)/triallyl isocyanurate (TAIC) photopolymer. Demineralized dentin was pretreated with 2-Hydroxyethyl methacrylate (HEMA)-containing primer. SEM fractography of adhesive-treated dentin demonstrated immediate complete tubule occlusion with significantly increased sealing depth to 140 μm, while the bonded interface remained stable under simulated oral conditions. This study provides a novel strategy to combat tooth sensitivity and recurrent decay.

Dental caries is a significant oral and public health problem worldwide, especially in low-income populations. The risk of dental caries increases with frequent intake of dietary carbohydrates, including sugars, leading to increased acidity and disruption of the symbiotic diverse and complex microbial community of health. Excess acid production leads to a dysbiotic shift in the bacterial biofilm composition, demineralization of tooth structure, and cavities. Highly acidic and acid-tolerant species associated with caries include Streptococcus mutans, Lactobacillus, Actinomyces, Bifidobacterium, and Scardovia species. The differences in microbiotas depend on tooth site, extent of carious lesions, and rate of disease progression. Metagenomics and metatranscriptomics not only reveal the structure and genetic potential of the caries-associated microbiome, but, more importantly, capture the genetic makeup of the metabolically active microbiome in lesion sites. Due to its multifactorial nature, caries has been difficult to prevent. The use of topical fluoride has had a significant impact on reducing caries in clinical settings, but the approach is costly; the results are less sustainable for high-caries-risk individuals, especially children. Developing treatment regimens that specifically target S. mutans and other acidogenic bacteria, such as using nanoparticles, show promise in altering the cariogenic microbiome, thereby combatting the disease.

The main source of commercial chitosan is the extensive deacetylation of its parent polymer chitin. It is present in green algae, the cell walls or fungi and in the exoskeleton of crustaceans. A novel procedure for preparing chitosan from shrimp shells was developed. The procedure involves two 10-minutes bleaching steps with ethanol after the usual demineralization and deproteinization processes. Before deacetylation, chitin was immersed in 12.5 M NaOH, cooled down and kept frozen for 24 h. The obtained chitosan was characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV, X-ray diffraction (XRD) and viscosimetry. Samples of white chitosan with acetylation degrees below 9 % were obtained, as determined by FTIR and UV-first derivative spectroscopy. The change in the morphology of samples was followed by SEM. The ash content of chitosan samples were all below 0.063 % . Chitosan was soluble in 1 % acetic acid with insoluble contents of 0.62 % or less. XRD patterns exhibited the characteristic peaks of chitosan centered at 10 and 20 degrees in 2 θ . The molecular weight of chitosan was between 2.3 and 2.8 × 10 5 g/mol. It is concluded that the procedure developed in the present work allowed obtaining chitosans with physical and chemical properties suitable for pharmaceutical applications.