Water Scavenger Research Articles

Zirconium catalyzed amide formation without water scavenging

A scalable homogeneous metal‐catalyzed protocol for direct amidation of carboxylic acids is presented. The use of 2–10 mol% of the commercially available Zr(Cp)2(OTf)2·THF results in high yields of amides at moderate temperature, using an operationally convenient reaction protocol that circumvents the use of water scavenging techniques.

A simple method to enhance the lifetime of Ni-rich cathode by using low-temperature dehydratable molecular sieve as water scavenger

Ni-rich cathode materials have received much attention because of their high specific capacity, low cost and environmentally friendly characteristic. However, the nickel-rich cathode is extremely sensitive to moisture, which results in poor structure stability and electrochemical performance. Herein, we demonstrate an efficient and simple route to prolong the lifetime of nickel-rich cathode by introducing a low-temperature dehydratable molecular sieve as water scavenger. The residual water content in electrolyte measurement and nuclear magnetic resonance test manifest that molecular sieve can effectively fix the trace H2O and reduce the decomposition rate of electrolyte from 16.6% to 4.0%, respectively. Transmission electron microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy confirm that the molecular sieve inhibits the fragmentation of the electrode and the side reactions on the surface of the cathode. This approach improves structural integrity and stabilizes surface structure of the cathode, which increases the capacity retention without sacrificing rate performance. This effective strategy can be extended to other cathode materials which are sensitive to moisture to realize good cycling stability.

First known larva of omicrine genus Psalitrus d’Orchymont (Coleoptera, Hydrophilidae)

The larval morphology of the water scavenger beetlePsalitrusyamatensisHoshina & Satô, 2005 is described based on a specimen collected from Fukuoka Prefecture, Kyushu, Japan. This is the first description of the larval morphology of the hydrophilid genusPsalitrusd’Orchymont, 1919, as well as the first description of larval chaetotaxy of the tribe Omicrini. Species-level identification of the larva was performed using DNA barcoding of a molecular marker: a 658 bp fragment of the mitochondrial cytochrome oxidase I. A description including chaetotaxy of head capsule and head appendages, diagnosis, and illustrations of the larva is provided.Psalitruslarvae can be distinguished from other known larvae of the tribe Omicrini by the morphology of the head and legs. The larva shares characters with other known larvae of Omicrini; potential plesiomorphies are shared with Cylominae and aquatic hydrophilids; some characters are also shared with larvae of Megasternini and Sphaeridiini.

Three additional new genera of acidocerine water scavenger beetles from the Guiana and Brazilian Shield regions of South America (Coleoptera, Hydrophilidae, Acidocerinae).

Recent study of the water scavenger beetle subfamily Acidocerinae in the Neotropical region has uncovered numerous undescribed species that are not able to be placed in existing genera. Here, we describe three new genera to accommodate 17 of these new species from South America: Aulonocharesgen. nov. for Aulonochareslingulatussp. nov. (French Guiana, Suriname), Aulonocharesnovoairensissp. nov. (Brazil), and Aulonocharestubulussp. nov. (Brazil, Guyana, Suriname, Venezuela); Ephydrolithusgen. nov. for Ephydrolithushamadaesp. nov. (Brazil), Ephydrolithusminorsp. nov. (Brazil), Ephydrolithusogmossp. nov. (Brazil), Ephydrolithusspiculatussp. nov. (Brazil), and Ephydrolithustelisp. nov. (Brazil); and Primocerusgen. nov. for Primoceruscuspidissp. nov. (Venezuela), Primocerusgigassp. nov. (Venezuela), Primocerusneutrumsp. nov. (Guyana, Suriname, Venezuela), Primocerusocellatussp. nov. (Venezuela), Primoceruspetilussp. nov. (Brazil), Primoceruspijiguaensesp. nov. (Venezuela), Primocerusmaipuresp. nov. (Venezuela), Primocerussemipubescenssp. nov. (Guyana), and Primocerusstriatolatussp. nov. (Suriname). The genus Ephydrolithusgen. nov. is currently known to be restricted to seepages in the mountainous regions of the Brazilian Shield. Aulonocharesgen. nov. and Primocerusgen. nov. are both currently only known from the Guiana Shield, though widespread in that region where they are associated with streams and seeps. We present differential diagnoses, maps, habitat details, and illustrations of all new genera and species here described.

A counting method for the number of Sternolophus rufipes and Hydrochara affinis in a noisy trap image

Abstract A quantitative survey of water scavenger beetles Sternolophus rufipes and Hydrochara affinis in paddy fields is essential not only for evaluating the impact of climate change on ecosystems but also for quantifying the stability of paddy fields. Many researchers classify insects in insect traps visually and manually count the number of individuals in each species. This manual survey method is time-consuming, fatiguing, and tedious. In this paper, we present a simple method to classify and count beetles in noisy trap images. The proposed method uses the beetles' body size and spots made by the light reflecting off the backs of beetles. We verify the method using images of beetles attached to the insect trap. The results demonstrate that the number of individuals in each species as counted by the proposed method and the manually counted number are statistically identical, which means that our method is sufficient to replace the existing manual counting method. Additionally, we briefly discuss the limitations of this counting method and ideas that could complement them.

Improved Synthesis of Unsymmetrical Carbonate Derivatives Using Calcium Salts

An effective synthetic method for unsymmetrical carbonate species has been developed. Calcium oxide and calcium hydroxide were found to be highly effective for this reaction, affording unsymmetrical carbonates in high yield and purity. Calcium chloride, which is a coproduct, serves as a water scavenger that can be easily removed. Additional drying processes and complicated purification steps are not necessary in this reaction. This improved process is important in terms of green sustainable chemistry principles.

On the Conversion of Bauxite Ores to Highly Activated Alumina Media for Water Remediation

AbstractGood quality drinking water is necessary to maintain a high quality of life. Millions lack access to clean and safe drinking water, and current trends suggest that billions will face acute water shortages in the coming decades. Development of new materials has led to technological impacts on water purification, from desalination membranes to atmospheric water scavenging. However, the most challenging aspect of technological solutions is cost: if the community being serviced cannot afford the solution, it is not likely to be sustainable. Repurposing Earth‐abundant materials to replace highly engineered solutions is an atractive solution. Herein, minimal processing of bauxite rocks produces a high‐porosity and reactive activated alumina in situ, without purification directly from the ore. This acid‐treated, thermally activated bauxite (ATAB) exhibits a high surface area of 401 ± 6 m2 g−1, a 40‐fold increase relative to its parent ore, and a 2× increase relative to the state‐of‐the‐art fluoride adsorbent, activated alumina. The composition, preparation, and mechanism of adsorption are studied by X‐ray diffraction, X‐ray photoelectron spectroscopy, and multiple‐quantum magic‐angle spinning 27Al nuclear magnetic resonance (NMR). The maximum adsorption density of ATAB is comparable with that of activated alumina, but ATAB requires fewer processing steps, thus warranting future consideration as a primary adsorbent of choice for fluoride removal from water.

1,1,1,3,3,3-Hexamethyldisilazane (2018).

1,1,1,3,3,3-Hexamethyldisilazane (HMDZ) is used industrially to treat the surface of silica, as an intermediate adhesion promoter or silylating agent in the semiconductor industry, as a chemical modifier of inorganic fillers, and as a water scavenger silicone sealant. In animal studies, HMDZ is considered to be slightly to at most moderately toxic following acute administration via oral, dermal, and inhalation routes of exposure. HMDZ is neither an eye irritant nor was it dermally irritating under semiocclusive conditions; however, it caused dermal necrosis in two studies under occlusive conditions. HDMZ is not genotoxic or mutagenic in in vitro assays and was not reproductively or developmentally toxic in an inhalation screening study in rats. Short-term and subacute, high-dose inhalation exposure to HMDZ produced respiratory tract irritation, reduced feed consumption, changes in clinical chemistry parameters, and reversible central nervous system depression in rats. In a 90-day inhalation exposure study in rats, HMDZ exposure-related effects were observed in the kidneys of male rats but were determined to be alpha-2µ-nephropathy, thus, not relevant to humans. Based on the results of the 90-day (subchronic) inhalation study, 75 ppm was determined to be the no-observed adverse effect level (NOAEL) and was selected as the point of departure for the derivation of the 8-h time-weighted average (TWA), health-based workplace environmental exposure level (WEEL) value. This subchronic inhalation NOAEL was adjusted to account for duration of exposure, interindividual variability, and intraindividual variability. The resulting 8-h TWA WEEL value of 10 ppm is fully expected to provide a significant margin of safety against any potential adverse health effects in workers following long-term inhalation exposure to HMDZ vapor. A 15-min short-term exposure limit of 50 ppm was also established to protect workers from reversible effects produced by acute, high-dose inhalation of HMDZ vapor. A skin notation (Skin) is warranted because of the potential for the dermal route to significantly contribute to the overall exposure to HMDZ.

Efficient removal of uranium(VI) by layered double hydroxides supported nanoscale zero-valent iron: A combined experimental and spectroscopic studies

In this study, nanoscale zero-valent iron (nZVI) supported on layered double hydroxide (LDH) composite (LDH@nZVI) was prepared, characterized and applied to U(VI) scavenging in water. Removal of U(VI) as a function of pH, ionic strength, reaction time, initial concentrations of U(VI), and temperature were studied and compared with pure LDH and nZVI, the LDH@nZVI had best U(VI) removal efficiency owning to the excellent synergistic combination of LDH adsorption and nZVI reduction. XPS analysis found that surface oxygen functional groups and surface-bound Fe(II) played a critical role in U(VI) remediation. The large surface areas (334.0 m2/g), abundant functional groups (i.e., MO, CO and OH), rapid kinetics (adsorption equilibrium within 1 h) and excellent adsorption capacities (176 mg/g) indicating that LDH@nZVI can be considered as a potential material for preconcentration of U(VI) from sewage water.

A Direct Method for the Efficient Synthesis of Benzylidene Acetal at Room Temperature

For the first time, a metal‐free direct method has been developed for the efficient synthesis of benzylidene acetal at room temperature using Dowex 50WX8 as a solid acid catalyst and Cl3CCN as a novel water scavenger. At room temperature, a wide variety of aryl and α,β‐unsaturated aldehydes react readily with functionalized 1,2‐ and 1,3‐diols to furnish the corresponding acetals in very good yields. Labile functional groups, like N‐Boc, N‐Cbz, ‐OTBDMS, ‐OBn, ‐N3 and acetonide are found to be stable under the reaction conditions. The versatility of this method is further demonstrated with carbohydrate substrates and optically active diols.

Fabrication of methyl acrylate and tetraethylenepentamine grafted magnetic chitosan microparticles for capture of Cd(II) from aqueous solutions.

MCS-MA-TEPA microparticles, with 251.22 mg g-1 of adsorption capacity for Cd(II), higher than most of the counterparts, were first fabricated by chemical coprecipitation, spray drying, and Michael addition reaction, without any cross-linker participation. These Fe3O4-nanoparticle-embedded microparticles of 5.95 μm in size, derived from modifications by methyl acrylate (MA) and tetraethylenepentamine (TEPA) on magnetic chitosan (MCS) microparticles, were of plum-pudding-like and wrinkle-like topography portrayed by TEM and SEM. Such features were beneficial to adsorbent recycling and Cd(II) capture. BET examinations illustrated 6.084 m2 g-1 of specific surface area, 0.015 mL g-1 of pore volume, and 6.536 nm of pore diameter. FTIR, VSM, XRD, TEM-SAED, TG, and DTG characterizations were indicative of successful synthesis, satisfactory magnetism, well-defined architecture, and good thermostability. Optimal adsorption parameters for Cd(II) were determined via batch experiments. Thermodynamic parameters and adsorption data fitting implied an exothermic, spontaneous, monolayer, and chemisorption process. XPS analyses confirmed a potential adsorption mechanism that N and O atoms on microparticles chelated with Cd(II) ions in solutions. Additionally, MCS-MA-TEPA-Cd(II) microparticles were magnetically separated easily and had outstanding reusability even after five-time recycling, with a slight adsorption capability loss (< 12%). Altogether, MCS-MA-TEPA microparticles might serve as a promising adsorbent for contaminated water scavenging.

In-Place Modulation of Rectification in Tunneling Junctions Comprising Self-Assembled Monolayers.

This paper describes tunneling junctions comprising self-assembled monolayers that can be converted between resistor and diode functionality in-place. The rectification ratio is affected by the hydration of densely packed carboxylic acid groups at the interface between the top-contact and the monolayer. We studied this process by treatment with water and a water scavenger using three different top-contacts, eutectic Ga–In (EGaIn), conducting-probe atomic force microscopy (CP-AFM), and reduced graphene oxide (rGO), demonstrating that the phenomena is molecular in nature and is not platform-speciffc. We propose a mechanism in which the tunneling junctions convert to diode behavior through the lowering of the LUMO, which is suffcient to bring it close to resonance at positive bias, potentially assisted by a Stark shift. This shift in energy is supported by calculations and a change in polarization observed by X-ray photoelectron spectroscopy and Kelvin probe measurements. We demonstrate light-driven modulation using spiropyran as a photoacid, suggesting that any chemical process that is coupled to the release of small molecules that can tightly bind carboxylic acid groups can be used as an external stimulus to modulate rectification. The ability to convert a tunneling junction reversibly between a diode and a resistor via an effect that is intrinsic to the molecules in the junction extends the possible applications of Molecular Electronics to reconfigurable circuits and other new functionalities that do not have direct analogs in conventional semiconductor devices.

Selective Adsorption toward Hg(II) and Inhibitory Effect on Bacterial Growth Occurring on Thiosemicarbazide-Functionalized Chitosan Microsphere Surface

The work presented here aims to fabricate dual-purpose adsorbent with adsorption selectivity for Hg(II) and antibacterial activity. TSC-PGMA-MACS microspheres were first constructed via esterification of malic acid (MA) with chitosan (CS) and through successively grafting glycidyl methacrylate (GMA) and thiosemicarbazide (TSC) onto MACS microsphere surfaces. Fourier transform infrared spectroscopy, elemental analysis, energy-dispersive X-ray spectrometry, X-ray diffraction, differential scanning calorimetry, thermogravimetry, differential thermogravimetry, scanning electron microscopy, and Brunauer-Emmett-Teller results provided ample evidence that new mesoporous adsorbent, with 35.340 m2 g-1 of specific surface area and abundant -NH2 and C═S, was successfully fabricated and had loose crystalline, thermodynamically stable, and well-defined architectures, beneficial for Hg(II) adsorption and bacterial cell killing. Optimal adsorption parameters were determined via varying pH, time, concentrations, and temperatures, and pH 6.0 was chosen as an optimal pH for Hg(II) adsorption. Adsorption behavior, described well by pseudo-second-order kinetic and Langmuir isotherm models, and thermodynamic parameters implied a chemical, monolayer, endothermic, and spontaneous adsorption process, and the maximum adsorption capacity for Hg(II) was 242.7 mg g-1, higher than most of the available adsorbents. Competitive adsorption exhibited excellent adsorption selectivity for Hg(II) in binary-metal solutions. Besides, TSC-PGMA-MACS microspheres had outstanding reusability even after five times recycling, with adsorption capability loss <14%. Several potential adsorption sites and bonding modes were proposed. Notably, TSC-PGMA-MACS microspheres before and after adsorption were of high antibacterial activity against Escherichia coli and Staphylococcus aureus (MICs, 2 and 0.25 mg mL-1), superior to CS powders, and possible antibacterial mechanisms were also summarized. Altogether, dual-purpose TSC-PGMA-MACS microspheres might be promising adsorbent for contaminated water scavenging.

Comparative analysis of diagnostic and phylogenetic chaetotaxic characters of Berosus Leach and their implications on the relationships of the tribe Berosini (Coleoptera: Hydrophilidae)

Larvae of water scavenger beetles are found in all types of aquatic and semi-aquatic environments and play an important role in the structure of these communities. Despite their diversity, morphological characters that allow the identification of larvae at species level are usually inconspicuous. In this paper we analyze the head capsule and mouthparts chaetotaxy of hydrophilid larvae belonging to the tribe Berosini, with the purpose of identifying variations on the external sensory organs that may be used for species delimitations. We focus on two species of Berosus Leach (Berosus festivus Berg, 1885 and Berosus patruelis Berg, 1885) and compare larval structures within Berosus and among other genera of Berosini. We include morphometric characters together with detailed illustrations of all characters, SEM images of selected structures and micrographs of a sensory organ present on the inner margin of the first antennomere which is a novelty within larval Coleoptera. Our analysis shows that the number, shape, relative position and organization of sensilla, especially those of labroclypeus and mouthparts, provide diagnostic characters for the separation of Berosus species. Also, we found a new set of characters derived from chaetotaxy that supports current phylogenetic relationships within the tribe Berosini. Most of these chaetic characters are associated with structures that have undergone strong modifications as adaptation to a benthic lifestyle in the clade Berosus + Hemiosus.

Biology and morphology of immature stages of banana-associated Protosternum beetles, with comments on the status of Taiwanese endemic P. abnormale (Coleoptera: Hydrophilidae)

The available data on the biology of the water scavenger beetle genus Protosternum Sharp, 1890 (Hydrophilidae: Sphaeridiinae: Protosternini) are summarized, indicating an obligate association of Protosternum beetles with banana plants (Musaceae): they inhabit decaying tissues of old banana stems in which adult feeding, larval development and pupation takes place. Second and third instar larvae and pupa of the Taiwanese-endemic P. abnormale (Orchymont, 1913) are described in detail, based on field-collected specimens associated with co-occurring adults by cox1 DNA barcodes. Larvae are unique in the Hydrophiloidea by having strongly asymmetrical mouthparts with a large basal bifid tooth on the right mandible, indicating a specialized prey preference. Putative larval synapomorphies of the Protosternini are revealed, based on the comparison of the Protosternum larva with that of Sphaerocetum. Taxonomic status of P. abnormale is revealed to be confused by previous authors due to the absence of male specimens and is clarified here. Two new species are described based on specimens previously misidentified as P. abnormale: P. malayanum sp. nov. from Sumatra and Peninsular Malaysia, and P. hainanense sp. nov. from Hainan.

Chlorotrimethylsilane-promoted synthesis of 1,2,4-triazolopyrimidines from 3,5-diamino-1,2,4-triazoles and pentane-2,4-diones

An efficient synthesis of 2-amino-1-R-[1,2,4]triazolo[1,5-a]-pyrimidinium or 3-amino-2-R-[1,2,4]triazolo[4,3-a]pyrimidi- nium chloride derivatives by heterocyclization of 3,5-diamino-1-R-1,2,4-triazoles (R = Alk or Ar) with pentane-2,4-diones was developed. The process is promoted by chlorotrimethyl- silane which plays the dual role of carbonyl-activating agent and water scavenger.

High diversity of Cetiocyon beetles (Coleoptera: Hydrophilidae) along an elevational gradient on Mt. Wilhelm, New Guinea, with new records from the Bird's Head Peninsula

A major component of the “Our Planet Reviewed – Papua New Guinea” project was to evaluate insect diversity along an elevational gradient on Mt. Wilhelm (Madang Province, Papua New Guinea), the fourth highest peak in New Guinea. Flight intercept traps were installed at eight sites separated by approximately 500 m in elevation from 200 m a.s.l. to 3700 m a.s.l. Here we focus on the water scavenger beetle genus Cetiocyon (Coleoptera: Hydrophilidae) collected as part of this project. Cetiocyon species are uniform in much of their external morphology, but diagnostic characters are found in the male genitalia. Our aim was to test the hypothesis that local species diversity was high, and that Cetiocyon species diversity is elevationally structured. A small amount of additional material from western New Guinea (Bird’s Head Peninsula: Arfak Mts.) was also examined. Ten new species are described, seven from Mt. Wilhelm Cetiocyon paweli sp.n., C. depilis sp.n., C. onyx sp.n., C. augai sp.n., C. ibiscanus sp.n., C. mogianus sp.n., and C. gemellus sp.n., and three from the Arfak Mountains: C. jakli sp.n., C. colossus sp.n., and C. hamifer sp.n.. Twelve Cetiocyon species were found on the slopes of Mt. Wilhelm, most of which were only found at one or two neighboring elevations. The largest diversity of species was found at intermediate elevations (1200 – 1700 m). We successfully sequenced the 3’ end of mitochondrial cox1 gene for 10 species, which we used along with morphological characteristics to infer a species level phylogeny and examine the effect of elevation on species diversity. Interspecific genetic distances were significantly lower at higher elevations on Mt. Wilhelm, and our phylogenetic reconstruction suggests that Cetiocyon ancestrally inhabited low or intermediate elevations. As the result of recent research eighteen Cetiocyon species are currently known form New Guinea. An updated identification key to all New Guinean species is included, along with photographs and illustrations of relevant morphological characters.

A new species and a new record of Pelthydrus Orchymont, 1919 from Yunnan, China (Coleoptera: Hydrophilidae: Hydrophilinae).

The members of the genus Pelthydrus are small-sized aquatic beetles which belong to the water scavenger beetle family Hydrophilidae. At present the lineage includes 63 valid species mainly occurring in Asia, with 21 known from China (Bian et al. 2008, 2009; Hansen 1999; Schönmann 1995). One new species is described here, which belongs to the Pelthydrus sculpturatus species group, bringing the total number of species within the group to seven (Schönmann 1995). One additional species is reported from China for the first time. Specimens were collected from Yunnan Province and are deposited in IAECAS (Institute of Applied Ecology, Shenyang, Chinese Academy of Sciences).

Morphology and biology of the flower‐visiting water scavenger beetle genus Rygmodus (Coleoptera: Hydrophilidae)

AbstractHydrophilidae (water scavenger beetles) is well known as an aquatic beetle family; however, it contains ca. 1,000 secondarily terrestrial species derived from aquatic ancestors. The New Zealand endemic genus Rygmodus White is a member of the hydrophilid subfamily Cylominae, which is the early‐diverging taxon of the largest terrestrial lineage (Cylominae + Sphaeridiinae) within the Hydrophilidae. In this paper we report that Rygmodus beetles are pollen‐feeding flower visitors as adults, but aquatic predators as larvae. Based on analyses of gut contents and a summary of collecting records reported on museum specimen labels, adult Rygmodus beetles are generalists feeding on pollen of at least 13 plant families. Rygmodus adult mouthparts differ from those of other (saprophagous) hydrophilid beetles in having the simple scoop‐like apex and mola with roughly denticulate surface, resembling the morphology found in pollen‐feeding staphylinid beetles. Larvae were found along the sides of streams, under stones and in algal mats and water‐soaked moss; one collected larval specimen was identified using DNA barcoding of two molecular markers, mitochondrial cytochrome oxidase 1 (cox1) and nuclear histone 3 (H3). Larvae of two species, Rygmodus modestus and Rygmodus sp., are described in detail and illustrated; they closely resemble ambush‐type predatory larvae of the hydrophilid tribe Hydrophilini in the head morphology. Rygmodus is the only known hydrophilid beetle with adults and larvae inhabiting different environments.

Three new genera of acidocerine water scavenger beetles from tropical South America (Coleoptera, Hydrophilidae, Acidocerinae).

Recent collecting efforts in the Neotropics have led to the discovery of numerous new species and lineages of aquatic beetles. Here, three new genera are described to accommodate fifteen new species of water scavenger beetles of the subfamily Acidocerinae from northern South America: Crucisternum gen. n. for C. escalera sp. n. (Venezuela), C. ouboteri sp. n. (Guyana, French Guiana, Suriname, Venezuela), C. queneyi sp. n. (French Guiana), C. sinuatus sp. n. (Brazil), C. toboganensis sp. n. (Venezuela), C. vanessae sp. n. (Suriname), and C. xingu sp. n. (Brazil); Katasophistes gen. n. for K. charynae sp. n. (Peru), K. cuzco sp. n. (Peru), K. merida sp. n. (Venezuela) and K. superficialis sp. n. (Ecuador); and Nanosaphes gen. n. for N. castaneus sp. n. (Brazil), N. hesperus sp. n. (Suriname), N. punctatus sp. n. (Guyana), and N. tricolor sp. n. (Guyana, Suriname). It was also found that the monotypic Neotropical endemic genus Dieroxenus Spangler, 1979, syn. n. is congeneric with Chasmogenus Sharp, 1882 resulting in the single new combination Chasmogenus cremnobates (Spangler, 1979), comb. n.. Katasophistes merida sp. n. is known exclusively from seepage habitats, while the remaining taxa described herein are primarily associated with the margins of densely forested streams. Diagnoses, illustrations, distribution maps, and habitat summaries are provided for all new genera and species. A key to the genera of Acidocerinae of the New World is provided.