Hydrochloride Aqueous Solution Research Articles

Development of super nanoantimicrobials combining AgCl, tetracycline and benzalkonium chloride

In this work, we demonstrate that a simple argentometric titration is a scalable, fast, green and robust approach for producing AgCl/antibiotic hybrid antimicrobial materials. We titrated AgNO3 into tetracycline hydrochloride (TCH) aqueous solution, thus forming AgCl/TCH in a one-step procedure. Furthermore, we investigated the one-pot synthesis of triply synergistic super-nanoantimicrobials, combining an inorganic source of Ag+ ions (AgCl), a disinfecting agent (benzyl-dimethyl-hexadecyl-ammonium chloride, BAC) and a molecular antibiotic (tetracycline hydrochloride, TCH). Conventional antimicrobial tests, industrial biofilm detection protocols, and in situ IR-ATR microbial biofilm monitoring, have been adapted to understand the performance of the synthesized super-nanoantimicrobial. The resulting hybrid AgCl/BAC/TCH nanoantimicrobials are found to be synergistically active in eradicating Salmonella enterica and Lentilactobacillus parabuchneri bacteria and biofilms. This study paves the way for the development of a new class of super-efficient nanoantimicrobials that combine relatively low amounts of multiple active species into a single (nano)formulation, thus preventing the development of antimicrobial resistance towards a single active principle.

Comparative Evaluation of Microorganism Disinfection Methods for N95 Respirators

Background: An excessive demand for N95 respirators occurred during the SARS-CoV-2 pandemic. Therefore, health care workers were obligated to reuse N95 respirators, which were intended to be disposable. Aim: The primary objective of this study was to establish a standard procedure for safe disinfection or sterilization that does not affect the performance of an N95 respirator. Methods: As disinfection or sterilization methods, immersion in 70% ethanol, 0.1% hypochlorous acid, 0.3% peracetic acid, 0.2% alkyldiaminoethylglycine hydrochloride aqueous solution, hypochlorous acid water, or plant mineral-activated water, autoclaving, pasteurization and hydrogen peroxide plasma sterilization were used. After sterilization/disinfection, the filtration capacity of each N95 respirator was examined. Findings: The performance changes in the N95 respirator caused by each sterilization/disinfection method differed for each manufacturer’s product. Seventy percent ethanol, 0.1% sodium hypochlorite aqueous solution, 0.3% peracetic acid aqueous solution, autoclaving, hypochlorous acid water, and plant mineral-activated water significantly deteriorated the performance of N95 respirators. Performance degradation (increased permeability) was observed in 0.2% alkyldiaminoethylglycine hydrochloride aqueous solution and hydrogen peroxide plasma sterilization, and the permeation performance significantly deteriorated by 50–70% in all N95 respirators tested. Only pasteurization resulted in no deterioration in performance, even after five repeated sterilizations. Conclusion: Verification of sterilization/disinfection methods for the reuse of N95 respirators has shown that the currently recommended hydrogen peroxide plasma sterilization is inadequate as it increases permeability by more than 50% with a single treatment. In this study, pasteurization was found to be the optimal sterilization method.

Polymeric Inclusion Membranes Based on Ionic Liquids for Selective Separation of Metal Ions.

In this work, poly(vinyl chloride)-based polymeric ionic liquid inclusion membranes were used in the selective separation of Fe(III), Zn(II), Cd(II), and Cu(II) from hydrochloride aqueous solutions. The ionic liquids under study were 1-octyl-3-methylimidazolium hexafluorophosphate, [omim+][PF6-] and methyl trioctyl ammonium chloride, [MTOA+][Cl-]. For this purpose, stability studies of different IL/base polymer compositions against aqueous phases were carried out. Among all polymer inclusion membranes studied, [omim+][PF6-]/PVC membranes at a ratio of 30/70 and [MTOA+][Cl-]/PVC membranes at a ratio of 70/30 were able to retain up to 82% and 48% of the weight of the initial ionic liquid, respectively, after being exposed to a solution of metal ions in 1 M HCl for 2048 h (85 days). It was found that polymer inclusion membranes based on the ionic liquid methyl trioctyl ammonium chloride allowed the selective separation of Zn(II)/Cu(II) and Zn(II)/Fe(III) mixtures with separation factors of 1996, 606 and, to a lesser extent but also satisfactorily, Cd(II)/Cu(II) mixtures, with a separation factor of 112. Therefore, selecting the appropriate ionic liquid/base polymer mixture makes it possible to create polymeric inclusion membranes capable of selectively separating target metal ions.

Rapid extraction and detection of five alkaloids in dried khat by solvent extraction-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry

Khat is a common plant that grows primarily in Eastern Africa and the Arabian Peninsula. Cathinone, norpseudoephedrine, and norephedrine are the main psychoactive components of khat. Experimental studies have shown that red and green khat have similar cathinone contents, but green khat contains more norpseudoephedrine and norephedrine than red khat. Research indicates that Ethiopians believe that red khat has stronger psychoactive effects than green khat. Therefore, we speculated that other substances in red khat may enhance its psychoactive effects. Using the sampling method, we identified two other psychoactive components in khat: methcathinone and ethcathinone. At present, only a few studies on the extraction and detection of alkaloids from khat have been published in China, and no reports on the extraction and detection of methcathinone and ethcathinone from khat are available. In this study, we established an extraction and detection method for five alkaloids in dried khat using high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLC-Q-TOF MS). To establish the extraction method, we optimized the extraction solvent and process. The amounts of dichloromethane and sodium hydroxide added during the purification step were also optimized. To establish the detection method, we optimized the chromatographic and MS conditions. The final extraction and detection method was as follows: Dried khat powder (0.1 g) was loaded into a polypropylene centrifuge tube, added with 1 mL of 0.05 mol/L hydrochloride aqueous solution, and vortex-oscillated for 3 min for extraction. The sample was centrifuged at 10000 r/min for 3 min. Next, 600 μL of the supernatant was placed in a centrifuge tube, added with 1 mL of dichloromethane, shaken for 1 min, and centrifuged at 10000 r/min for 3 min. Subsequently, 300 μL of the supernatant was placed in a centrifuge tube, added with 80 μL of 1 mol/L sodium hydroxide aqueous solution, shaken for 1 min, and added with 1 mL of acetonitrile. Vortex oscillation was performed for 2 min to extract the sample, after which solid sodium chloride (0.4 g) was added to the mixture, followed by shaking for 1 min to separate the acetonitrile and aqueous phases. The mixture was then centrifuged at 10000 r/min for 3 min. Finally, the supernatant was collected and diluted for further testing. The five target analytes were separated on a ZORBAX Eclipse Plus Phenyl-Hexyl column (100 mm×3.0 mm, 1.8 μm) via gradient elution using 0.1% acetic acid aqueous solution and acetonitrile as mobile phases with a flow rate of 0.3 mL/min and column temperature of 30 ℃. The analytes were identified using the targeted MS/MS method under positive electrospray ionization mode and quantified using the external standard method. The five alkaloids showed good correlations (all correlation coefficients (r2)≥0.9976) with their respective linear ranges. The limits of detection were between 0.08 and 0.75 μg/L, and the limits of quantification were between 0.25 and 2.50 μg/L. The average recoveries of the five alkaloids from two plants with different alkaloid contents were between 90.7% and 105.2%. The intra-sample precision ranged from 0.5% to 2.3%, the intra-day precision was between 1.0% and 2.5%, and the inter-day precision was between 1.3% and 3.3%. Using the developed method, we extracted and analyzed 15 khat samples, and detected five alkaloids. This method enables rapid sample pretreatment and has high sensitivity, good stability, and suitable accuracy. Based on the above results, we conclude that the proposed method meets the inspection and identification requirements for khat. Thus, it can provide a valuable reference for the physical and chemical identification of khat and support for further studies on its psychoactive components.

Enhanced Photocatalytic Degradation of Antibiotics by Ag/BiOI/g‐C3N4 Composites

As an efficient, safe, and environmentally friendly technology, semiconductor photocatalysis has been widely used in the removal of antibiotics from wastewater. In this work, a novel Ag/BiOI/g‐C3N4 composite photocatalytic material, BiOI/g‐C3N4, g‐C3N4, and BiOI are prepared as the photocatalysts. The morphologies, chemical properties, and photocatalytic performances of the photocatalysts are characterized using scanning electron microscope, transmission electron microscope, X‐ray diffraction, X‐ray photoelectron spectroscopy, Fourier‐transform infrared spectrometer, ultraviolet–visible spectroscopy (UV–Vis) diffuse reflectance spectra, and photoluminescence spectra. In addition, tetracycline hydrochloride (TC) and ceftiofur sodium aqueous solutions are used to simulate wastewater and the photocatalytic degradation performances of the photocatalysts are investigated and compared under visible light. Compared to g‐C3N4, BiOI, and BiOI/g‐C3N4, the Ag/BiOI/g‐C3N4 demonstrates superior performance, increasing the removal rates of TC and ceftiofur sodium to 85.6% and 90.2%, respectively. The photocatalytic mechanism of the Ag/BiOI/g‐C3N4 may involve the promotion of the visible light–harvesting ability and inhibition of the recombination of photogenerated electron/hole pairs. Furthermore, the primary active groups in the system are identified as superoxide radicals (·O2−) and hydroxyl radicals (·OH). Herein, some valuable insights into the development of innovative photocatalytic materials are offered for the effective removal of antibiotics from water.

Highly effective synthesis of 5-hydroxymethylfurfural from lignocellulosic biomass over a green and one-pot reaction in biphasic system

In this study, different types of lignocellulosic biomas were used as substrates for the conversion to 5-HMF via biphasic reaction system that is composed of a reaction phase (aqueous phase) and an extraction phase (organic phase) under the catalysis of various metal salts. Deep eutectic solvents (DESs), ionic liquid [BMIM]Cl, aqueous choline chloride, aqueous betaine hydrochloride, and ethylamine hydrochloride were used as the reaction phase in the combination of dimethyl sulfoxide (DMSO) as organic solvents. The highest yields of 5-HMF obtained from pineapple stems in reactions with DES were 40.98%, 37.26%, and 23.44% for ChCl:Lac, ChCl:OA, and EaCl:Lac, respectively. Moreover, the combination of dimethyl sulfoxide, betaine hydrochloride aqueous solution, and AlCl3·6H2O with the pineapple stem conversion system resulted in a maximum yield of 61.04% ± 0.55% of 5-HMF. This study also demonstrated that AlCl3·6H2O and betaine hydrochloride could be effectively reused four times, which indicates a green and effective process.

Modification of large tow textile grade polyacrylonitrile fiber by dopamine hydrochloride to prepare low-cost carbon fibers

Owing to high specific strength and modulus, low density, corrosion resistance, etc., polyacrylonitrile (PAN)-based carbon fibers (CFs) have been widely used in aerospace, new energy, sporting goods, and other fields. However, their application in some civil fields is limited due to their high price. Textile grade polyacrylonitrile fiber (TPF) has a structure similar to the PAN precursor of PAN-based CFs and its cost is also comparatively low, which could be expected to replace the PAN precursor in the preparation of low-cost CFs. However, the lack of active groups in the initial copolymer of TPFs leads to rapid cyclization and extremely exothermic reaction in the pre-oxidation process, which further results in the danger of fiber melting and combustion. In the present work, surface impregnation of TPFs in dopamine hydrochloride aqueous solution together with a further ultrasonic treatment were carried out, and successive pre-oxidation and carbonization resulted in the formation of TPF-based CFs. The results showed that the cyclization temperature of modified TPFs decreased significantly and the exothermic peak also widened with the introduction of oxygen anion of dopamine hydrochloride during the pre-oxidation process, and the microstructure characterization detected by FTIR, XRD and Raman confirmed that the functional groups of dopamine hydrochloric were helpful to accelerate the formation of a ladder structure. Owing to the controllable evolution of fiber architectures during the whole heat treatment process, the final tensile strength and tensile modulus of obtained TPF-based CFs were 3.31GPa and 223.80GPa, respectively.

Bio-inspired hierarchical structure of polyaniline in the pore surface of polymer film through interfacial polymerization as a smart material sensitive to pH

The bio-inspired hierarchical structure of polyaniline (PANI) was fabricated in the pore surface of polymer film through interfacial polymerization. The porous polystyrene (PS) honey-comb patterned (HCP) film containing benzoyl peroxide (BPO) was first fabricated by the breath figure (BF) method under humid conditions, further, the film was immersed into aniline hydrochloride aqueous solution for the interfacial polymerization of PANI. The interfacial polymerization of the HCP porous film led to the biomimetic growth of PANI in fractal configuration for a bio-inspired snowflake or leaf-like pattern in the pore surface. The bio-inspired structure of PANI in the HCP porous film through interfacial polymerization is explained by the diffusion-leading aggregation (DLA) by the reaction of aniline monomer into an aqueous solution and self-assembled BPO in the pore surface. The morphology of the bio-inspired PANI structure in the HCP film was highly sensitive to pH, and revealed the conductivity variation over several orders of magnitude (10-3 to 10-1 S/cm) similar to a smart material. Due to the high pH sensitivity, the film can be applied in various biomedical sensing applications.

Constructing 2D layered PCN/Ti3C2/Bi2MoO6 heterojunction with MXene as charge mediator for enhanced photocatalytic performance

In this article, a novel 2D/2D/2D PCN(protonated g-C3N4)/Ti3C2/Bi2MoO6 ternary Z-scheme heterojunction was successfully prepared through hydrothermal method and electrostatic self-assembly method. The photocatalytic performance of the ternary 2D/2D/2D PCN/Ti3C2/Bi2MoO6 composites was evaluated by photo-degradation of tetracycline hydrochloride (TC-HCL) aqueous solution under visible light irradiation (λ > 420 nm). Compared with Bi2MoO6, PCN, Ti3C2/Bi2MoO6 and 5% PCN/Bi2MoO6, 5% PCN/Ti3C2/Bi2MoO6 composites exhibited higher photocatalytic activity. The degradation ratio of tetracycline hydrochloride aqueous solution reached 81.3%. The enhanced photocatalytic performance benefits from the 2D layered structure of surface-to-surface contact, which not only shortens the charge transfer distance, but also provides a large number of channels for charge transfer. A Z-scheme charge transfer mechanism was proposed, in which Ti3C2 acted as an electron transfer mediator to accelerate the transfer of photogenerated electrons between Bi2MoO6 and PCN. The possible photocatalytic mechanism was proposed based on the trapping experiment and band alignment of the composite.

Topotactic transformed face-to-face heterojunction of BiOCl/Bi2WO6 for improved tetracycline photodegradation

Heterojunction engineering, especially face-to-face heterojunction, is considered as a serviceable approach to manipulate the activity of photocatalysts. Herein, a face-to-face heterojunction of BiOCl/Bi2WO6 was fabricated by a simple in situ topotactic transformation process. By using BiOCl sheets as building block, a close and face-contact BiOCl/Bi2WO6 heterointerface was obtained because Bi2WO6 sheets were generated on the surface of BiOCl sheets through metathesis Cl- with WO42-. The obtained heterojunctions were characterized by various methods to identify the successful preparation and characteristics. The photocatalytic activities of BiOCl/Bi2WO6 heterojunctions were investigated under visible light irradiation by degradation of tetracycline hydrochloride aqueous solution. The experimental results suggested that BiOCl/Bi2WO6 heterojunctions exhibit significant enhanced efficiency for tetracycline hydrochloride degradation compared with pure BiOCl. The enhanced activity can be attributed to the efficient carrier separation and transfer benefiting from lots of carrier transfer channels in heterointerface and extended visible light harvesting ability of Bi2WO6. The work highlights that the fabrication of heterojunctions by constructing close and large-area contact heterointerface is beneficial to enhance the pollutant degradation activity.

Determination of multiple drugs of abuse in human urine using dispersive liquid–liquid microextraction and capillary electrophoresis with PDA detection

A new method was developed for pre-concentration and determination of multiple drugs of abuse in human urine using dispersive liquid–liquid microextraction (DLLME) and capillary electrophoresis (CE) with photodiode array detection. The method was based on the formation of tiny droplets of an organic extractant in the prepared sample solution using water-immiscible organic solvent (chloroform) dissolved in water-miscible organic dispersive solvent (isopropyl alcohol). The organic phase, which extracted eight drugs of abuse from the prepared urine solution, was separated by centrifugation. The sedimented phase was transferred into a small volume CE auto-sampler vial with 10 µL of 1% HCl methanol solution and evaporated to dryness. The residue was reconstituted in lidocaine hydrochloride (internal standard) aqueous solution and introduced by electrokinetic injection into CE. Under the optimum conditions, acceptable linear relationship was observed in the range of 3.0–500 ng/mL with the correlation coefficient ( r ) of 0.9982–0.9994 for spiked urine samples. The limit of detection (LOD) (S/N = 3) was estimated to be 1.0 ng/mL. A recovery of 75.7%–90.6% was obtained for spiked samples. The mean relative error (MRE) was within ±7.0% and the relative standard deviation (RSD) was less than 6.9%. The proposed DLLME-CE procedure offers an alternative analytical approach for the sensitive detection of drugs of abuse in real urine samples. Key points: The dispersive liquid-liquid microextraction (DLLME) was involved for the determination of drugs in urine with capillary electrophoresis with photodiode array detection (CE-PDA). Good linearity, sensitivity, recovery and precision were achieved. The proposed method was eco-friendly with microliter scale solvent consumption.

Continuous Flow Process for the Synthesis of Betahistine via Aza-Michael-Type Reaction in Water

A continuous flow process for the preparation of betahistine with a 90% isolated yield has been reported. 2-Vinylpyridine and saturated methylamine hydrochloride aqueous solution were used as start...

Extraction of Zinc Metal ions from Aqueous Solution Using Ionic Liquids

<p>This work analyzes the extraction behavior of transition heavy metal Zinc and other metal ions such as Copper, and Cadmium from hydrochloride aqueous solution in the absence of chelating agents by using a novel class of hydrophobic ionic liquids. Ionic liquid for this study was synthesized based on 1-(n-alkyl)-3-methylimidazolium cations and hexafluorophosphate anions followed by the metathesis route at room temperature were evaluated. The advantages of using these ionic liquids include their simple synthesis and sustainability. Which makes them “Greener and Simpler” compared to other solvents used for metal extraction. The experimental results show that ionic liquid 1-Butyl-3-methylimidazolium hexafluorophosphate, [BMPSM][PF6] entirely removed of Zinc (extraction percentage 94.4%) and other Copper and Cadmium heavy metals from the aqueous solutions. Based on the results, the use of ionic liquids for selected heavy metal ions as a substitute to the traditional extraction agents in liquid/liquid extraction of heavy metal ions shows considerable potential and is quite promising and promoting for further extraction.</p>

Spinel CuxCo1−xMn2O4 electrode for effectively cleaning organic wastewater via electrocatalytic oxidation

Development of anodes with high electrocatalytic activity, electrochemical stability and low cost is a key to clean organic wastewater via electrocatalytic oxidation. Here, spinel CuxCo1−xMn2O4 (CCM-X) was prepared by introducing copper with high catalytic activity into the structurally stable spinel CoMn2O4. The CCM-X were coated on the surface of titanium plate and used as anodes to study their electrocatalytic oxidation performance for cleaning simulated organic wastewater (tetracycline hydrochloride aqueous solution). The maximum removal ratio of 20 mg L−1 tetracycline hydrochloride was 91.3% in 120 min and still reached 84.9% after 5-times’ reusing of the anode, which was attributed to the high electrocatalytic activity, oxygen evolution potential (1.70 V vs. Ag/AgCl) and stable structure of multi-metal oxide CCM-X anode. In addition, free radical trapping experiments showed that hydroxyl radicals played a major role in electrocatalytic oxidation process. Electrochemical tests showed that redox of Co(III)/Co(IV) and Mn(III)/Mn(IV) participated in the electrocatalytic oxidation reaction, and doping Cu can effectively improve the electron transfer ability and electrocatalytic activity of CCM-X. Therefore, CCM-X/Ti electrodes perform attractive application prospects in cleaning organic wastewater via electrocatalytic oxidation.

High-performance polyacrylonitrile-based pre-oxidized fibers fabricated through strategy with chemical pretreatment, layer-by-layer assembly, and stabilization techniques

Novel high-performance polyacrylonitrile (PAN)-based pre-oxidized fibers (i.e. OPFHA-MEA-L) with improved thermal stability and flame-retardant and mechanical properties were designed and made from the pristine PAN fibers through chemical pretreatment with hydroxylamine hydrochloride (HA) and monoethanolamine (MEA) aqueous solutions, then coated with chitosan (CS) and sodium tripolyphosphate (STPP) via layer-by-layer (LbL) assembly, and finally followed by stabilization in the air. The morphological structure, flammability, and thermal and mechanical properties of fabricated OPFs were systemically investigated. The results indicated that the PAN fibers after chemical pretreatment with HA and MEA had a large amount of hydrophilic groups. It would facilitate the increase of pre-oxidation degree for PAN fibers during stabilization and the deposition of positively and negatively charged CS-STPP flame-retardant coating. The fabricated OPFs (i.e. OPFHA-MEA-10) demonstrated superior comprehensive properties with charred residue of about 68.2%, breaking strength of about 295.1 N, breaking elongation of 12.6%, and limiting oxygen index value of about 41.5%, respectively, contributing to the improved thermal stability and flame-retardant and mechanical properties. It is envisioned that this innovative type of high-performance OPFs could be utilized for potential applications as flame retardant and in high temperature filtration.

Perovskite LaFexCo1-xO3-λ deposited SiO2 catalytic membrane for deeply cleaning wastewater

To improve the cleaning efficiency of the membranes for wastewater, perovskite LaFexCo1-xO3-λ deposited SiO2 catalytic membrane (PCM) with functionality of peroxymonosulfate (PMS) induced catalytic oxidation and membrane separation was prepared by employing LaFexCo1-xO3-λ deposited SiO2 as the functional layer on diatomite support. The perovskite LaFexCo1-xO3-λ deposited SiO2 functional layer was modified by doping Fe, which contributed to the generation of oxygen vacancies, resulting in the massive generation of singlet oxygen and sulfate radicals during the pollutant degradation processes. Besides, the heterogeneous catalyst was effectively immobilized by PCM, and the mass transfer was enhanced owing to the adequate curved channels and eddy diffusion, performing a preferable catalytic oxidation efficiency and permeability. The water yield and degrading efficiency for tetracycline hydrochloride aqueous solution (20 mg/L) were 1064.5 L/m2h and 99%, respectively. Simulated wastewater containing organic pollutant and oil was treated by PCM, demonstrating an attractive separation and catalytic performance. Furthermore, cycling and regeneration test indicated that the PCM exhibited favorable stability and regeneration abilities after 10 consecutive cycles. Therefore, PCM with capacities of separation and catalytic oxidation performed potential application in complex wastewater treatment.

The inhibitory mechanism of l-lysine hydrochloride on the ice crystals growth by molecular dynamics

Understanding the inhibitory mechanism of cryoprotective agent on ice growth is essential for preventing the cryoinjury of vivo biological tissue and for the bioactive protection of protein medicine in cryopreservation processes. The crystallization growth process of (0 2 0) crystal face of orthorhombic ice in l-lysine hydrochloride aqueous solutions was researched by molecular dynamic. The results indicated that l-lysine ion has a competitive adsorption on the lattice sites of ice interface with water molecule. The binding carboxyl (COO−) and flexible l-lysine chain can disrupt the periodic continuous growth of ice. The free l-lysine ion and chlorine anion (Cl−) inhibit the diffusion of water molecules which makes ice crystals difficult to grow. This final results proved that l-lysine ion can inhibit ice crystal growth in both aqueous and crystalline phases.

Rapid analysis of a doxycycline hydrochloride solution by metallic mesh device-based reflection terahertz spectroscopy.

Terahertz (THz) spectroscopy has the advantages of non-ionization and spectroscopic fingerprint, which can be used for biological and chemical compound analysis. However, because of the strong absorption of water in the THz region, it is still a challenge for THz waves to realize aqueous solution detection. In this study, taking a doxycycline hydrochloride (DCH) aqueous solution as the target, we proposed a THz metallic mesh device (MMD) based reflection platform for the first time for sensing. The angle characteristics of the THz MMD was investigated through numerical simulations and experimental measurements to get an optimized configuration for the platform. When the projection of THz electric field polarization onto the MMD plane gets parallel to latitudinal direction of the MMD apertures, a strong resonant surface mode can be achieved, and our proposed platform can be successfully used to detect the DCH solution with a concentration as low as 1 mg L-1. The sensing mechanism of our platform was also explored by analyzing the influences of the immersion depth into the MMD holes and the extinction coefficient of droplets on the reflection spectra. Our work presents a rapid, low-cost, and practical platform for antibiotic solution sensing using THz radiation, which opens new avenues for the microanalysis of chemicals or biomolecules in strongly absorptive solutions in the THz region.

Chlorine K-Edge X-Ray Absorption Near-Edge Structure Analysis of Clarithromycin Hydrochloride Metastable Crystal

X-ray absorption fine structure (XAFS) spectra, especially X-ray absorption near-edge structure (XANES), show unique features depending on the chemical states and structures in the vicinity of the X-ray absorbing elements. As such, they can be used to identify the chemical environment of elements. XAFS spectroscopy was applied to investigate the chemical environment of chloride ions in a metastable form A crystal of the antibiotic clarithromycin hydrochloride hydrate. The XANES of the form A crystals showed low similarity to that of the active pharmaceutical ingredient (API) hydrochloride salt crystals, but showed a high similarity to that of a hydrochloride aqueous solution. This indicated that the chloride ion in the form A crystals predominantly interacted with water molecules and was fully hydrated, which was consistent with the previous presumption that form A may be high water-content crystals. This study demonstrated that this XAFS spectroscopy method would be a potent alternative technique for evaluating APIs.

Fungicides Reduce the Abundance of Yeast-like Symbionts and Survival of White-Backed Planthopper Sogatella furcifera (Homoptera: Delphacidae).

The white-backed planthopper (WBPH) Sogatella furcifera is one of the most harmful pests of rice in Southeast Asia. The fat body of WBPH harbors intracellular yeast-like symbionts (YLS). YLS are vertically transmitted to WBPH offspring by transovarial infection. YLS play an important role in the WBPH life cycle. YLS diversity and function have been extensively studied in the brown planthopper (BPH) and small brown planthopper but not in WBPH, even though a novel strategy for controlling the BPH based on suppressing YLS has been proposed. Here, using denaturing gradient gel electrophoresis, we identified 12 unique fungal sequences among YLS of WBPH, and five of them represented uncultured fungi. We then fed WBPH with rice plants treated with different fungicides [70% propineb wettable powder (WP) (PR), 70% propamocarb hydrochloride aqueous solution (AS) (PH), 25% trifloxystrobin and 50% tebuconazole water-dispersible granules (WG) (TT), 40% pyrimethanil suspension concentrate (SC) (PY), and 50% iprodione SC (IP)] and evaluated their effects on YLS abundance and WBPH survival rate. Both YLS abundance and adult WBPH survival rate were significantly decreased upon feeding fungicide-treated rice plants, and exposure to 50% IP resulted in the strongest reduction. The abundance of two Sf-YLS species (Ascomycetes symbiotes and Cla-like symbiotes) was significantly reduced upon exposure to 50% IP. The counts of Ascomycetes symbiotes, the most abundant YLS species, were also suppressed by the other fungicides tested. In conclusion, 50% IP was the most effective fungicide, reducing YLS abundance and WBPH survival rate under controlled conditions, suggesting its potential use to control WBPH.