Hexamethylenetetramine Research Articles

Use of methenamine hippurate to prevent urinary tract infections in community adult women: a systematic review and meta-analysis.

BackgroundUrinary tract infections (UTIs) are often treated with antibiotics and are a source of antibiotic overuse.AimTo systematically review randomised controlled trials (RCTs) of adult women in the community with a history of recurrent UTIs and who use methenamine hippurate prophylactically.Design and settingSystematic review of women in the UK, Australia, Norway, and US (aged ≥18 years) with recurrent UTIs receiving methenamine hippurate against placebo or no treatment, and antibiotics.MethodThe authors searched three databases, clinical trial registries, and performed forward–backward citation analysis on references of included studies.ResultsSix studies involving 557 participants were included (447 were analysed). Of the six studies, five were published and one was an unpublished trial record with results, three compared methenamine hippurate against placebo or control, and three compared methenamine hippurate with antibiotics. For the number of patients who remained asymptomatic, methenamine hippurate showed a non-statistically significant trend of benefit versus antibiotics over 12 months (risk ratio [RR] 0.65, 95% confidence interval [CI] = 0.40 to 1.07, I2 49%), versus control over 6 or 12 months (RR 0.56, 95% CI = 0.13 to 2.35, I2 93%), and a non-statistically significant trend versus any antibiotic for abacteruria (RR 0.80, 95% CI = 0.62 to 1.03, I2 23%). A similar non-statistically significant trend of benefits for methenamine hippurate for the number of UTI or bacteriuric episodes was found, and a non-statistically significant difference in the number of patients experiencing adverse events between methenamine hippurate and any comparator, with a trend towards benefit for the methenamine hippurate, was identified. Antibiotic use and resistance were not consistently reported.ConclusionThere is insufficient evidence to be certain of the benefits of methenamine hippurate to prevent UTI. Further research is needed to test the drug’s effectiveness in preventing UTIs and as an alternative for antibiotic treatment for UTI.

Some interaction-related thermodynamic properties of aqueous tetramethylenediethylenetetramine (drug teotropine) solutions: Effect of the solvent H/D isotope substitution and temperature

The molar enthalpies of dissolution of 1,3,6,8-tetraazatricyclo[4.4.1.13,8]dodecane or TMDETA (tetramethylenediethylenetetramine: the teotropine pharmaceutical) in ordinary (H2O) and heavy (D2O) water were measured calorimetrically at T = (278.15, 288.15, 298.15, 308.15, and 318.15) K and p = 0.1 MPa. The standard molar enthalpies and heat capacities of TMDETA dissolution/hydration, along with D2O–H2O solvent isotope effects (IEs) in these quantities, were computed. Solution enthalpies and corresponding IEs were found to be negative, decreasing in magnitude as the temperature is rising. It was concluded that hydrophobic effects are the predominant part in the TMDETA hydration and they are enhanced in D2O and weakened going from TMDETA to its lower-molecular aminal derivative, hexamethylenetetramine (HMTA) being the known drug urotropine. Unlike the aqueous HMTA, the “dualistic” character of TMDETA hydration is less dependent on the initial structure state of a solvent isotopologue. The results of analyzing the contributions to the solvation enthalpy within the scope of Scaled Particle Theory showed that IEs in the enthalpy of TMDETA – water interaction and the solvent cavity formation is almost cancelling each other at T > 288.15 K.

Alternative to Prophylactic Antibiotics for the Treatment of Recurrent Urinary Tract Infections in Women (ALTAR): A Multi-Centre Randomised, Non-Inferiority Trial

Background: Systematic review of previous randomised controlled trials concluded that the non-antibiotic option of methenamine hippurate may be effective for urinary tract infection (UTI) prevention but outlined the need for further large, well-conducted randomised trials. We aimed to satisfy this requirement by testing its efficacy, compared to the current standard prophylactic treatment of daily low-dose antibiotics. Methods: This randomised, non-inferiority trial recruited from eight UK centres. Women with recurrent UTI, requiring prophylactic treatment, were randomly assigned (1:1), (using permuted blocks of variable length via a web-based system), to receive antibiotic prophylaxis or methenamine hippurate for 12-months. Treatment allocation was not masked and crossover between arms was permitted. The primary outcome was the absolute difference in symptomatic, antibiotic-treated UTI incidence during treatment. The non-inferiority margin was one UTI episode per person-year. Analyses performed in a modified intention-to-treat (mITT) population comprised all participants observed for at least six months. Trial registration was via ISRCTN registry, ISRCTN70219762. Findings: Between June 23, 2016 and June 20, 2018, 240 participants were randomised to antibiotic prophylaxis (n=120) or methenamine hippurate (n=120). The mITT analysis comprised 205 (85%) participants [102 (85%) antibiotics, 103 (86%) methenamine hippurate]. The incidence of antibiotic-treated UTI during the 12-month treatment period was 0·89 episodes per person-year (95% CI 0·65-1·12) in the antibiotic group and 1·38 (1·05-1·72) in the methenamine hippurate group with an absolute difference of 0·49 (90% CI 0·15-0·84) confirming non-inferiority. Adverse reactions were reported by 34/142 (24%) and 35/127 (28%) participants receiving antibiotics and methenamine hippurate respectively and the majority were mild. Interpretation: Non-antibiotic prophylactic treatment using methenamine hippurate should now be considered as a first-line option in women with a history of recurrent UTI episodes, given the robust demonstration of non-inferiority to daily antibiotic prophylaxis seen in this trial. Clinical Trial Registration Details: ISRCTN registry, ISRCTN70219762. Funding Information: National Institute for Health Research Health Technology Assessment Programme. Declaration of Interests: CH, HM, TH,TC , WK, JL, AAb, LV, RF, KW and AAl report grants from the National Institute for Health Research (NIHR) Health Technology Assessment (HTA) Programme pertaining to the reported study. All other authors have nothing to declare. Ethics Approval Statement: The study protocol was approved by North East Tyne and Wear South Research Ethics Committee (15/NE/0381) and has been published. All participants provided written informed consent.

Controlled titration-based ZnO formation.

Hexamethylenetetramine (HMTA) is commonly used as a base releasing agent for the synthesis of ZnO under mild aqueous conditions. HMTA hydrolysis leads to gradual formation of a base during the reaction. Use of HMTA, however, does have limitations: HMTA hydrolysis yields both formaldehyde and ammonia, it provides no direct control over the ammonia addition rate or the total amount of ammonia added during the reaction, it results in a limited applicable pH range and it dictates the accessible reaction temperatures. To overcome these restrictions, this work presents a direct base titration strategy for ZnO synthesis in which a continuous base addition rate is maintained. Using this highly flexible strategy, wurtzite ZnO can be synthesized at a pH >5.5 using either KOH or ammonia as a base source at various addition rates and reaction pH values. In situ pH measurements suggest a similar reaction mechanism to HMTA-based synthesis, independent of the varied conditions. The type and concentration of the base used for titration affect the reaction product, with ammonia showing evidence of capping behaviour. Optimizing this strategy, we are able to influence and direct the crystal shape and significantly increase the product yield to 74% compared to the ∼13% obtained by the reference HMTA reaction.

Seed-Mediated Synthesis and Photoelectric Properties of Selenium Doped Zinc Oxide Nanorods

Pristine ZnO and selenium doped ZnO (Se-ZnO) nanorods were successfully synthesized using seed-mediated hydrothermal method. The growth solution of both pure and Se-doped ZnO nanorods employed zinc nitrate hexahydrate (ZNH) and hexamethylenetetramine (HMT) as a precursor and surfactant, respectively. As a dopant source, selenium salt solution was obtained by reacting selenium powder with sodium borohydride at low temperature. The as-prepared pure ZnO and Se-doped ZnO nanorods were characterized using field effect scanning electron microscopy (FESEM), X-ray diffraction (XRD), UV-Visible spectroscopy (UV-Vis), and Photoluminescence (PL) spectroscopy. FESEM images show that the geometric shape of Se-ZnO nanoparticles is nanorods with a hexagonal cross-section. The XRD pattern shows the diffraction peak of the sample at the angles of 2θ: 34.44°, 36.25° and 47.54° which represents the hkl plane of (002), (101) and (102), respectively. The crystalline size calculated from XRD data is found to be in the range of 35-42 nm. The UV-Vis spectrum shows that Se-ZnO nanorods strong absorption peaks appeared in the range of 300-380 nm for all samples. Se doping has slightly altered the band gap energy of pure ZnO nanorods around 0.01 eV. The peak of the photoluminescence spectra of the sample at 470 nm indicates the blue emission band.

C3‐Formylation of Indoles in Continuous Flow

We have developed a continuous flow C3‐formylation technique for indoles using hexamethylenetetramine (HMTA) and iodine. A mixed solvent system of DMF–H2O (1:1, vol/vol) completely dissolves reagents and prevents clogging of microchannels during fluid flow. The continuous flow technique provides maximized mixing and excellent heat transfer efficiency. Thus, flow chemistry accelerates the rate of C3‐formylation of indoles in the absence of a strong acid, base, or metal catalyst. We show that high yields of C3‐formylated indoles (up to 83%) can be obtained at 150°C when the residence time is as low as 8 min.

Extraterrestrial hexamethylenetetramine in meteorites\u2014a precursor of prebiotic chemistry in the inner solar system

Despite extensive studies on the formation of organic molecules in various extraterrestrial environments, it still remains under debate when, where, and how such molecules were abiotically formed. A key molecule to solve the problem, hexamethylenetetramine (HMT) has not been confirmed in extraterrestrial materials despite extensive laboratory experimental evidence that it can be produced in interstellar or cometary environments. Here we report the first detection of HMT and functionalized HMT species in the carbonaceous chondrites Murchison, Murray, and Tagish Lake. While the part-per-billion level concentration of HMT in Murchison and Tagish Lake is comparable to other related soluble organic molecules like amino acids, these compounds may have eluded detection in previous studies due to the loss of HMT during the extraction processes. HMT, which can yield important molecules for prebiotic chemistry such as formaldehyde and ammonia upon degradation, is a likely precursor of meteoritic organic compounds of astrochemical and astrophysical interest.

Synthesis and Characterization of CuO Rods for Enhanced Visible Light Driven Dye Degradation.

Here, we report simple and efficient method to synthesize CuO rods using copper acetate, hexamethylenetetramine (HMTA) and sodium hydroxide (NaOH) solutions via hydrothermal process followed by calcination. The Field emission scanning electron microscopy images revealed that synthesized CuO rods were 2-4μm thick with several micrometers long and grown into high density. The as-synthesized CuO rods were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy and Energy dispersive X-ray analysis (EDS) which confirmed the formation of highly crystalline, single phase pure CuO rods with monoclinic structures. The photocatalytic capability of synthesized CuO rods was executed by monitoring the degradation of methylene blue (MB) dye under visible light illumination. The results showed MB dye degraded about ~70% in just 100 min and followed first order reaction kinetics with rate constant k = 0.01123 mint.1 and R² = 0.9880.

ZnAl nano layered double hydroxides for dual functional CRISPR/Cas9 delivery and enhanced green fluorescence protein biosensor

Evaluation of the effect of different parameters for designing a non-viral vector in gene delivery systems has great importance. In this manner, 2D crystals, precisely layered double hydroxides, have attracted the attention of scientists due to their significant adjustability and low-toxicity and low-cost preparation procedure. In this work, the relationship between different physicochemical properties of LDH, including pH, size, zeta potential, and synthesis procedure, was investigated and optimized for CRISPR/Cas9 delivery and reverse fluorescence response to the EGFP. In this manner, ZnAl LDH and ZnAl HMTA LDH were synthesized and characterized and applied in the HEK-293 cell line to deliver CRISPR/Cas9. The results were optimized by different characterizations as well as Gel Electrophoresis and showed acceptable binding ability with the DNA that could be considered as a promising and also new gold-standard for the delivery of CRISPR/Cas9. Also, the relationship of the presence of tertiary amines (in this case, hexamethylenetetramine (HMTA) as the templates) in the structure of the ZnAl LDH, as well as the gene delivery application, was evaluated. The results showed more than 79% of relative cell viability in most of the weight ratios of LDH to CRISPR/Cas9; fully quenching the fluorescence intensity of the EGFP/LDH in the presence of 15 µg mL−1 of the protoporphyrins along with the detection limit of below 2.1 µg mL−1, the transfection efficiency of around 33% of the GFP positive cell for ZnAl LDH and more than 38% for the ZnAl LDH in the presence of its tertiary amine template.

Investigating the performance of an organically cross-linked grafted copolymer gel under reservoir conditions for profile modifications in injection wells

The injection of cross-linked polymer gels to block high permeability zones and divert subsequent water/surfactant flooding to low permeability streaks to improve hydrocarbon production efficiency is commonly known as profile modification. Moreover, in a reservoir condition with high temperature, pH, and salinity, these cross-linked polymeric gels are unstable, leading to early syneresis. In this research work, poly(Acrylamide)-grafted-xanthan gum copolymer was synthesized by free radical polymerization using potassium persulfate as an initiator. Field-Emission Scanning Electron Microscopy and Fourier Transform Infrared spectroscopy characterize the grafted copolymer in this study. This grafted copolymer, which is soluble in water, was cross-linked with a low toxic organic cross-linker. The organic cross-linker is composed of hexamethylenetetramine (HMTA) and hydroquinone (HQ). The rheological examination and gelation conduct of this polymeric gel was analyzed using a bottle test. The experimental design in response surface method generated a second-order polynomial equation for the gelation time responses to the change in the reservoir parameters (salinity, pH, and temperature) and their interactions. The results exhibited that the response surface model can be applied successfully to analyze gelation time with the various reservoir parameters. Laboratory prepared sand pack flow experiment demonstrated a decent diverting capability of the grafted copolymer gel than commercially used polyacrylamide gels. Subsequently, this grafted copolymer gel can be suitable for profile modification jobs required for improving oil recovery from mature oil fields with high reservoir heterogeneities.

Microstructural properties, thermal insulation and thermal degradation behavior of boron‐containingmonolithic novolac xerogels

AbstractEnhancement of thermal stability‐insulation performance of hyper porous materials is the premier issue to design of novel porous thermal protection systems. Boron‐containing monolithic novolac xerogels (BCNXs) were synthesized using sol–gel networking of novolac resin with hexamethylenetetramine (HMTA) and boric acid at the solvent saturated vapor atmosphere (SSVA). The aim was to elucidate the effect of higher crosslinking density and thermal stable boron containing chemical bonds on the microstructure, thermal conductivity, and thermal oxidation stability of novolac xerogels. The results of FESEM and BET analysis showed that the microstructural characteristics of xerogels are significantly depend on the HMTA and boric acid concentration. The thermogravimetric results were analyzed using characteristic kinetic temperature (CKT)‐characteristic kinetic temperature range (CKTR) approximations. The effect of micromorphology of xerogels on the thermal conductivity was investigated. The effective thermal conductivity of samples were in the range of 0.031–0.048 W/m K.

Synthesis, Crystal Structure and Thermolysis of Cadmium Perchlorate Complex with Hexamethylenetetramine

The complex of cadmium perchlorate, [Cd(HMTA)2(H2O)4](ClO4)2•2H2O was synthesized by the reaction with hexamethylenetetramine (HMTA). C, H, N analyses, FT-IR, and X-ray crystallography were used to characterize the obtained complex. TG in the static air, simultaneous thermogravimetry-derivative thermogravimetry (TG-DTG), and differential scanning calorimetry (DSC) in streaming nitrogen atmosphere were evolved for thermal decay of prepared cadmium complex. To evaluate the reaction with quick warming, explosion delay measurements were attempted. The model-free isoconversional and model-fitting kinetic methodologies were applied to isothermal TG data for kinetic examination of the complex's thermal decomposition. At higher temperatures, the complex explodes to synthesize highly thermally stable residue most closely resembles cadmium oxide.

Structural and optical properties of α-Fe2O3 nanoparticles realized by simple thermal decomposition route

Herein, we present the synthesis and thermal treatment effect of Hematite (α-Fe2O3). Hematite nanoparticles were prepared by repeated calcination of a precursor obtained from Fe(NO3)3.9H2O and Hexamethylenetetramine (HMTA). Thermal treatment of the precursor at 400 °C for 4 h, resulted in the formation of Fe3O4 nanoparticles, which on repeated calcination at 400 °C, 500 °C and 600 °C, resulted in α-Fe2O3 nanoparticles. Synthesized samples were characterized by using X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman spectroscopy and UV–vis spectroscopy techniques. XRD result reveals the formation of cubic Fe3O4 phase at 400 °C, which is transformed into rhombohedral α-Fe2O3 polymorphs on repeated calcination. Crystallinity of the α-Fe2O3 is enhanced on repeated calcination up to 500 °C after that it gets slightly amorphized at 600 °C. Raman and FTIR results further corroborate the XRD result. Optical band gap of most crystalline α-Fe2O3, as estimated from UV–vis results, is 1.87 eV. Urbach energy of the samples has been calculated from absorption data, which shows the minimum value for most crystalline material. These findings demonstrate the close relation between structure and optical properties of α-Fe2O3.

Thermal Hazards for Autocatalysis and Stability in CSTR: Decomposition of Solution from Nitrolysis of Hexamethylenetetramine

AbstractNitrolysis solution is a kind of spent acid, obtained after the nitration and ripening of hexamethylenetetramine (HA). Its decomposition is generally spontaneous and hazardous. Therefore, the thermal hazards of a real nitrolysis solution were studied here. The prepared nitrolysis solution was analysed by isoperibolic experiments, differential thermal analysis (DTA), accelerating rate calorimetry (ARC), and a bursting point test. We employed non‐linear regression and ordinary differential equation (ODE) fitting methods to obtain kinetic parameters, such as 120.73 kJ mol−1 of the activation energy (E), 36.388 s−1 of the natural logarithm of the pre‐exponential factor (lnA), 1.155 of the reaction order, and 0.6615 of the catalytic index. Based on these kinetic parameters, thermal safety parameters were obtained to evaluate the hazards of a real nitrolysis solution from four aspects: severity, thermal stability, process hazards, and thermal sensitivity. The results indicate critical severity, high process hazards and thermal sensitivity, and very low thermal stability. The hazards due to real nitrolysis solution are higher than those of nitric ester explosives and azos. Further, the value of the initial mass ratio between the concentrated nitric acid and HA could severely pose safety risks during the nitration process. Additionally, the sensitivity analyses of the four process parameters (space‐time of CSTR, τCSTR; feeding temperature, T0; ambient temperature, Ta; specific cooling capacity, hS/V) were performed under the critical conditions for thermal stability in a continuous stirred tank reactor (CSTR). The suited margin of Ta could be 333.15–342.81 K with other determined process parameters.

Study of Supercapacitors for Use in Dye Sensitized Solar Cells

The storage of energy generated by photovoltaic system is one problem of it. In this aspect, integrated energy conversion and storage systems, IECSS, using supercapacitors are presented as a solution. Dye sensitized solar cell becomes a main candidate for use in IECSS due its variety of applications. Recent studies shown that zinc oxide (ZnO) is a natural candidate for use in solar cells and supercapacitor due to its high energy density of the order 650 A g-1. The aims of this paper were: i) the study of the influence of the morfology of nanostructured ZnO nanoparticles obtained by the hydrothermal method using distincts complexing agents: etylenediaminetetraacetic acid (EDTA); hexamethyltetramine (HMT) and diaminometanal (urea), besides commercial ZnO; ii) study of the ZnO and activated carbon at ratio X:Y of 10:90, 20:80 and 30:70 in proportion of mass (%) in the preparation of electrodes. The commercial ZnO, which presents particles with spherical and porous morphology, presented the best capacitance result 8.38 Fg-1 at 10:90 ratio, that demonstrates the ZnO is an excellent candidate for material for supercapacitor coupled with dye solar cell.

The effect of polymer type on the performance of gels

Owing to the formation heterogeneity, the difference of mobility between sweeping phsse and formation fluids, gravity segregation, the sweeping phase usually flows along the high permeability zone, which leads to the poor oil recovery. In general, gelling systems are used into the reservoir conformance improvement. The properties of gels are different for the different composition of gelling systems. In this paper, three polymers with different AMPS content were used to investigate the effect of polymer type on the performance of polymer gels. In addition, methenamine(MA) and hydroquinone(HQ) were employed as crosslinkers, thiourea(TH) was used as oxygen scavenger to improve the stability of polymers and gels. And the gelation time, strength and syneresis rate of gels were characterized respectively. The results showed that the stability of polymer and gel was enhanced with the increase of AMPS content, and the gelation time was increased with the increment of AMPS content. And an ultrastable thermal-resistance and salt-tolerance gel was developed with the AM/AMPS copolymer (AMPS content equals 70%), the syneresis rate was less 10% after heat treatment under the harsh conditions (temperature=130°C, salinity=223802.8mg/L) for 150 days.

Nonantibiotic treatments for urinary cystitis: an update.

Urinary tract infections (UTIs) are one of most common infections in everyday clinical practice. Given the increase in antimicrobial therapy resistance, there has been an increased interest in nonantibiotic treatment options for common infections. A review of the recent literature including on nonantibiotic options for management of UTIs, symptoms of cystitis and prevention of recurrent UTIs. The article provides an overview on alternative therapy to antibiotics in the treatment of cystitis and recurrent UTI prophylaxis, including alkalinization of urine, cranberry products, probiotics, NSAIDS, D-mannose, herbal medicine, methenamine hippurate, oral immunostimulants (immunotherapy), topical oestrogens, vitamins and acupuncture. The last few years of intense research has focused on an effort to find evidence to corroborate potentially efficacious non antibiotic treatments. However, alternative treatments for UTIs have not brought conclusive evidence that antibiotic usage can be replaced completely by nonantibiotic options. The reason for this is largely due to a lack of good-quality randomized controlled trials on this subject.

Additive Type Affects Fermentation, Aerobic Stability and Mycotoxin Formation during Air Exposure of Early-Cut Rye (Secale cereale L.) Silage

Whole-crop rye harvested before maturity represents a valuable forage for silage production. Due to the scarcity of data on fermentation characteristics and aerobic stability (ASTA) and the lack of information on mycotoxin formation during aeration of early-cut rye (ECR) silage after silo opening, we evaluated the effects of different additive types and compositions. Wilted forage was treated with various biological and chemical additives, ensiled in 1.5-L glass jars and stored for 64 days. Fermentation pattern, yeast and mould counts and ASTA were determined at silo opening. In total 34 mycotoxins were analysed in wilted forage and in silage before and after 240 h of air exposure. Chemical additives caused the lowest dry matter (DM) losses during fermentation accompanied with the lowest ethanol production and the highest water-soluble carbohydrate concentration. Aerobic deterioration, which started within two days after silo opening in silage left untreated and inoculated with homofermentative lactic acid bacteria, was prevented by the combined use of hetero- and homofermentative lactic acid bacteria and the chemical additive containing sodium nitrite, hexamethylene tetramine and potassium sorbate. Moreover, these two additives largely restricted the formation of the mycotoxin roquefortine C to < 0.05 mg kg−1 DM after aeration, whereas untreated silage contained 85.2 mg kg−1 DM.

A re-interpretation of the structure of the silver borate, Ag16B4O10, in the light of the extended Zintl-Klemm concept.

The borate Ag16B4O10 was synthesized at high temperature and at elevated oxygen pressures [Kovalevskiy et al. (2020). Chem. Sci. 11, 962-969]. Its structure consists of [B4O10]8- polyanions (isostructural to P4O10) embedded in an Ag matrix. According to the standard valences Ag+, B3+ and O2-, the formula has an excess of eight e- which the above authors proposed were located, pairwise, in four Ag4 tetrahedra within the silver substructure. That conclusion was based on the semiconducting and diamagnetic properties, as well as the very small `attractors' of the Electron Localization Function (ELF) found at the centre of these Ag4 tetrahedra. However, a large overlap of the projected density of states (DOS) of silver and oxygen indicated possible dispersion interactions between both atomic species. In this article, an alternative description is proposed based on the extended Zintl-Klemm concept. The anion [B4O10]8- can be formulated as Ψ-[N4O10] P4O10, if it is assumed that the eight e- are transferred to the four B atoms, so converting them into Ψ-N, this then makes sense of its similarity with P4O10, [N4(CH2)6], adamantane and tetraisopropyladamantane. When the Ag atoms connect to the O atoms, they arrange as the H atoms do in hexamethylenetetramine (HMTA). If the two lone pairs of each of the bridging O atoms in Ψ-[N4O10] are equated to the C-H bonds in HMTA, then, this same equivalence exists between the C-H bonds and the O-Ag bonds in the compound Ag16B4O10. The 24 Ag atoms surrounding each [B4O10]8- group prolong the sphalerite structure of the borate anion by means of Ag-O bonds which also fit the sphalerite structure formed of AgO. The eight excess electrons might then be distributed between the Ag and the O atoms, so making sense of the mixing of the Ag and O states. The Ag atoms bonded to the O atoms of the [B4O10]8- groups form a coat that interconnects the borate anions through Ag-O bonds. To establish the validity of this new proposal, the study needs to be extended to the compound Ag3B5O9.

A Study of the Chemistries, Growth Mechanisms, and Antibacterial Properties of Cerium- and Yttrium-Containing Nanoparticles.

Under the current climate, physicians prescribe antibiotics for treating bacterial infections, and such a limitation to a single class of drugs is disadvantageous since antibiotic-resistant bacteria have adapted to withstanding their stresses. Antibiotic alternatives are sought, and herein metal nanoparticles comprised of the rare earth elements cerium and yttrium were determined to invoke toxicity on methicillin-resistant Staphylococcus aureus (MRSA) and a multi-drug-resistant strain of Escherichia coli (MDR E. coli). Ceria nanoparticles, yttrium-doped ceria nanoparticles, and cerium-doped yttria nanoparticles were fabricated by a wet chemical route, homogeneous precipitation in hexamethylenetetramine (HMT). To demonstrate the drastic variations in nanoparticle structure and toxicity that occur when the synthesis method and solvent are substituted, two additional approaches involving solvothermal and hydrothermal reactions were pursued in the production of yttrium-containing nanoparticles. Intrinsic nanoparticle features of size, morphology, and composition were construed by physiochemical characterizations, which aided in the elaboration of chemical reaction and growth mechanisms. It was determined by in vitro plate count assays that ceria nanoparticles which had been doped using the yttrium metal precursor after 30 min of the HMT reaction, at 500 μg/mL, were the most effective at inhibiting MRSA growth without imposing significant cytotoxicity on human dermal fibroblast cells. A total of 500 μg/mL of cerium- and yttrium-containing nanoparticles, prepared in a 1:1 molar ratio, were similarly biocompatible and antimicrobial, in the case of MDR E. coli. Indeed, as this study showed, nanoalternatives to antibiotics are feasible, adaptable, and can be facilely produced. The possible clinical applications of the rare earth metal nanoparticles are variegated, and ceria and yttria nanoparticles are additionally credited in the literature as dynamic antioxidants, regulators of tissue regeneration, and anticancer agents.