Toxicity of indium arsenide, gallium arsenide, and aluminium gallium arsenide

A ratiometric fluorescent probe for selective detection of hypochlorite (ClO-) and gallium (III) (Ga3+) ions in environmental and food samples

Hypochlorite (ClO-) and gallium (Ⅲ) ions (Ga3+) have extensive applications in various human industries and daily activities. However, their inherent toxicity poses significant risks to environmental preservation and human well-being. Hence, the development of reliable and handy detection tools for ClO- and Ga3+ in the environment and food is crucial. In this study, a ratiometric fluorescent probe was prepared based on benzothiazolaldehyde and pyridine-2-carboxylic acid hydrazide, which exhibited exceptional performance characteristics for the selective detection of ClO- and Ga3+. These features include high specificity, low detection limits (0.28 μM for ClO-, 0.13 μM for Ga3+), mild pH conditions (pH 4-11 for ClO-, pH 6-11 for Ga3+), fast response time (within 30 s), as well as versatile applicability across different matrices such as water, soil, food, and plant samples. Additionally, this probe can be used with a smartphone color recognition app. The probe offers a convenient and effective tool for the detection of ClO- and Ga3+, demonstrating its potential application value in environmental monitoring and food safety.

Controllable synthesis and morphology-dependent light emission efficiency of Zn2GeO4 nanophosphors

Zn2GeO4 is considered a very promising alternative to current luminescent semiconductors. Previous results suggest that its emitted wavelength may depend on different variables, such as particle size and morphology, among others. In this work, we have prepared pure and highly homogeneous Zn2GeO4 nanorods under hydrothermal synthesis conditions with a willemite-like structure. Their luminescent properties have been explored and their band gap is estimated, which are distinct from those of previously reported Zn2GeO4 bulk particles. Therefore, our results identify particle morphology as a crucial factor for maximizing and fine-tuning the luminescence of Zn2GeO4 nano-phosphors.

Exposure to gallium arsenide nanoparticles in a research facility: a case study using molecular beam epitaxy

We evaluated GaAs nanoparticle-concentrations in the air and on skin and surfaces in a research facility that produces thin films, and to monitored As in the urine of exposed worker. The survey was over a working week using a multi-level approach. Airborne personal monitoring was implemented using a miniature diffusion size classifier (DiSCMini) and IOM sampler. Environmental monitoring was conducted using the SKC Sioutas Cascade Impactor to evaluate dimensions and nature of particles collected. Surfaces contamination were assessed analyzing As and Ga in ghost wipes. Skin contamination was monitored using tape strips. As and Ga were analyzed in urines collected every day at the beginning and end of the shift. The greatest airborne exposure occurred during the cutting operations of the GaAs Sample (88883 np/cm3). The highest levels of contamination were found inside the hood (As max = 1418 ng/cm2) and on the laboratory floor (As max = 251 ng/cm2). The average concentration on the worker's skin at the end of the work shift (3.36 ng/cm2) was more than 14 times higher than before the start of the shift. In weekly urinary biomonitoring an average As concentration of 19.5 µg/L, which was above the Società Italiana Valori di Riferimento (SIVR) reference limit for the non-occupational population (2.0 - 15 µg/L), but below the ACGIH limit (30 µg/L). Overall, airborne monitoring, surface sampling, skin sampling, and biomonitoring of worker confirmed the exposure to As of workers. Systematic cleaning operations, hood implementation and correct PPE management are needed to improve worker protection.

A comparative study of two thienopyrimidine Schiff base probes for sequential monitoring of Ga3+ and Pd2

Two Schiff base probes (S1 and S2) were prepared and synthesized by incorporating thienopyrimidine into salicylaldehyde or 3-ethoxysalicylaldehyde individually, with the aim of detecting Ga3+ and Pd2+ sequentially. Upon chelation with Ga3+, S1 and S2 exhibited fluorescence enhancement in DMSO/H2O buffer. Both S1-Ga3+ and S2-Ga3+ were quenched by Pd2+. The limit of detection for S1 in response to Ga3+ and Pd2+ was 2.86 × 10-7 and 4.4 × 10-9 M, respectively. For S2, the limit of detection for Ga3+ and Pd2+ was 4.15 × 10-8 and 3.0 × 10-9 M, respectively. Furthermore, the complexation ratios of both S1 and S2 with Ga3+ and Pd2+ were determined to be 1:2 through Job's plots, ESI-MS analysis, and theoretical calculations. Two molecular logic gates were constructed, leveraging the response behaviors of S1 and S2. Moreover, the potential utility of S1 and S2 for monitoring Ga3+ and Pd2+ in domestic water was verified.

Robust Optical Detection of Ga3+ by a Rhodamine- and Coumarin-Based Proficient Probe: Theoretical Investigations and Biological Applications

The present investigation highlights a rhodamine-B- and coumarin-based efficient probe that selectively detects Ga3+ over other metal ions. The active pocket of the ligand for trapping the metal ions and the binding stoichiometry of its Ga3+ complex were discovered by single-crystal X-ray diffraction (SC-XRD) analysis. This binding stoichiometry was further confirmed in the solution state by mass spectrometry and Job's plot. The detection limit was found to be at the nanomolar level. Pyrophosphate being a well-known quencher could easily quench the fluorescence intensity of the RC in the presence of Ga3+ and reversibly recognize Ga3+ in the solution. The spiro ring opening of the ligand after Ga3+ insertion is proposed to be the principal mechanism for the turn-on fluorescence response. This ring opening was confirmed by SC-XRD data and nuclear magnetic resonance (NMR) titration experiments. Both ground- and excited-state calculations of the ligand and complex have been carried out to obtain information about their energy levels and to obtain the theoretical electronic spectra. Furthermore, the live-cell imaging of the probe only and the probe after the addition of Ga3+ have been carried out in HaCaT cells and satisfactory responses were observed. Interestingly, with the help of this probe, Ga3+ can be tracked inside the intracellular organelle such as lysosomes along with other regions of the cell. The article highlights a rhodamine-coumarin-based probe for the detection of Ga3+ over other metal ions with a nanomolar level detection limit. Structural characterization of the ligand and its Ga3+ complex was investigated by SC-XRD. Density functional theory (DFT) and time-dependent DFT (TD-DFT) studies were carried out to explore the excited-state energies and electronic spectra. The application of the probe for the detection of Ga3+ in live cells has been explored, and positive responses were observed.

Thin-Film Waveguide Laser Spectroscopy: A Novel Platform for Bacterial Analysis

Bacterial sensing based on quantum cascade laser spectroscopy coupled with diamond or gallium arsenide thin-film waveguides is a novel analytical tool for gaining high-resolution infrared spectroscopic information of planktonic and sessile bacteria, as shown in the present study for Escherichia coli. During observation periods of up to 24 h, diamond and gallium arsenide thin-film waveguide laser spectroscopy was compared to information obtained via conventional Fourier transform infrared spectroscopy. The proliferation behavior of E. coli at those surfaces was complementarily investigated using atomic force microscopy and scanning electron microscopy.

Non-Toxic CuInS2 /ZnS Colloidal Quantum Dots for Near-Infrared Light-Emitting Diodes

Ternary CuInS₂ quantum dots (QDs) with photoluminescence that is tunable from the visible to the near-infrared (NIR) region are promising light-emitters for consumer electronics due to the absence of toxic elements such as Pb, Cd, or As. Despite the compelling performance of visible-light-emitting CuInS₂ QDs, reports on NIR emission remain limited, with modest efficiencies at wavelengths beyond 900 nm. In this work, the facile synthesis of NIR-emitting CuInS₂ /ZnS QDs is reported. A combination of two sulfur precursors w as used in the synthesis, comprising 1-dodecanethiol (DDT) and hexamethyldisilathiane (HMDS). The reactive HMDS facilitates faster nucleation and leads to a higher density of emissive Cu-deficiency sites. The resulting QDs exhibit high photoluminescence quantum efficiency (PLQE) of 65% at a long emission wavelength of 920 nm. Using these QDs, NIR light-emitting diodes (LED) are fabricated, which attain an external quantum efficiency (EQE) of 8.2%. This efficiency is comparable to the best reported PbS and InAs QD LEDs, and the emission wavelength exceeds that of lead iodide perovskites. This work thus marks one of the first reports of efficient NIR LEDs based on environmentally benign CuInS₂ QDs and may open up promising new applications in consumer electronic products.

Changes in Organ Weight, Sperm Quality and Testosterone Levels After Aluminum (Al) and Indium (In) Administration to Wistar Rats

BACKGROUND

Aluminum and indium are widely used in industrial manufacturing, in pharmaceutical products, in medical treatments, and in food packaging, so they could reach organisms by different way. In order to clarify whether these elements are dangerous, we already demonstrated the ultrastructural modifications observed in the testicles, the epididymides, and the seminal vesicles of rat. Their pro-oxidative effect was also confirmed concomitantly to a decrease in anti-oxidant defenses in the blood, the testicles, and the liver. Thus, it seemed very logic to evaluate damages in the reproductive organs, especially on the exocrine and endocrine functions of the testicles.

METHODS

Aluminum and indium were intraperitoneally administered to male Wistar rats. Sperm solution was obtained from cauda epididymides. Motility, viability, density, and malformation of spermatozoa solution were assessed. Serum total unconjugated testosterone concentrations were measured using RIA technique.

RESULTS

Our results showed a decrease in weight of the testicles, epididymides, and seminal vesicles of indium-treated rats and an increase in the weight of their kidneys. A decrease in motility, viability, and density of epididymides stored sperm as well as generation of many spermatozoa malformations was also observed especially in indium-treated rats. Testosterone levels were increased in indium but were enhanced in aluminum group. This confirmed our previous studies showing that aluminum and indium are toxic for the testicular tissues. This could be explained by the generation of reactive oxygen species (ROS) affecting strongly the exocrine and the endocrine functions of the testicles.

CONCLUSION

Aluminum and indium are disturbing elements for the exocrine and endocrine functions of rat testicles.

Micro-/Nano-Structured Biodegradable Pressure Sensors for Biomedical Applications

The interest in biodegradable pressure sensors in the biomedical field is growing because of their temporary existence in wearable and implantable applications without any biocompatibility issues. In contrast to the limited sensing performance and biocompatibility of initially developed biodegradable pressure sensors, device performances and functionalities have drastically improved owing to the recent developments in micro-/nano-technologies including device structures and materials. Thus, there is greater possibility of their use in diagnosis and healthcare applications. This review article summarizes the recent advances in micro-/nano-structured biodegradable pressure sensor devices. In particular, we focus on the considerable improvement in performance and functionality at the device-level that has been achieved by adapting the geometrical design parameters in the micro- and nano-meter range. First, the material choices and sensing mechanisms available for fabricating micro-/nano-structured biodegradable pressure sensor devices are discussed. Then, this is followed by a historical development in the biodegradable pressure sensors. In particular, we highlight not only the fabrication methods and performances of the sensor device, but also their biocompatibility. Finally, we intoduce the recent examples of the micro/nano-structured biodegradable pressure sensor for biomedical applications.

Future food contaminants: An assessment of the plant uptake of Technology-critical elements versus traditional metal contaminants

Technology-critical elements (TCEs) include most rare earth elements (REEs), the platinum group elements (PGEs), and Ga, Ge, In, Nb, Ta, Te, and Tl. Despite increasing recognition of their prolific release into the environment, their soil to plant transfer remains largely unknown. This paper provides an approximation of the potential for plant uptake by calculating bioconcentration factors (BCFs), defined as the concentration in edible vegetable tissues relative to that in cultivation soil. Here data were obtained from an indoor cultivation experiment growing lettuce, chard, and carrot on 22 different European urban soils. Values of BCFs were determined from concentrations of TCEs in vegetable samples after digestion with concentrated HNO3, and from concentrations in soil determined after 1) Aqua Regia digestion and, 2) diluted (0.1 M) HNO3 leaching. For comparison, BCFs were also determined for 5 traditional metal contaminants (TMCs; As, Cd, Cu, Pb, and Zn). The main conclusions of the study were that: 1)BCF values for the REEs were consistently low in the studied vegetables;2)the BCFs for Ga and Nb were low as well;3) the BCFs for Tl were high relative to the other measured TCEs and the traditional metal contaminants; and 4) mean BCF values for the investigated TCEs were generally highest in chard and lowest in carrot. These findings provide initial evidence that there are likely to be real and present soil-plant transfer of TCEs, especially in the case of Tl. Improvements in analytical methods and detection limits will allow this to be further investigated in a wider variety of edible plants so that a risk profile may be developed.

Arsenic: A Review on a Great Health Issue Worldwide

Arsenic intoxication represents a worldwide health problem and occurs mainly through drinking water. Arsenic, a metalloid and naturally occurring element, is one of the most abundant elements in the earth’s crust, whose toxicity depends on the reduction state. The trivalent arsenicals are more toxic than the pentavalent arsenicals. In the trivalent state, inorganic and organic arsenic may react with thiol groups in proteins inhibiting their activity, whereas inorganic arsenic in the pentavalent state may replace phosphate ions in several reactions. Arsenic induces various epigenetic changes in mammalian cells, both in vivo and in vitro, often leading to the development of various types of cancers, including skin, lung, liver, urinary tract, prostate, and hematopoietic cancers. Potential mechanisms of arsenic toxicity in cancer include genotoxicity, altered DNA methylation and cell proliferation, co-carcinogenesis, tumor promotion, and oxidative stress. On the other hand, the FDA-certified drug arsenic trioxide provides solutions for various diseases, including several types of cancers. Detoxification from arsenic includes chelation therapy. Recently, investigations of the capability of some plants, such as Eucalyptus camadulensis L., Terminalia arjuna L. and Salix tetrasperma L., to remove arsenic from polluted soil and water have been studied. Moreover, nanophytoremediation is a green technology including the nanoscale materials used for absorption and degradation of organic and inorganic pollutants, such as arsenic compounds. This brief review represents an overview of arsenic uses, toxicity, epigenetics, and detoxification therapies.

Soil gallium speciation and resulting gallium uptake by rice plants

Gallium (Ga) is widely used in high-tech industries and is an emerging contaminant in the environment. This study aimed to determine Ga speciation in soils and Ga accumulation in rice plants (Oryza sativa L.) grown in three Ga-contaminated soils. The results showed that, among the soils, the acidic soil with a coarse texture had the highest soil Ga availability, which enhanced Ga uptake by rice roots. The Ga K-edge X-ray absorption near edge structure and sequential extraction results of the soils showed that the predominant species of Ga associated with iron hydroxides transformed to Ga(OH)₃ precipitates, and the residue fraction increased with rice-growing time, resulting in lower Ga uptake by rice roots in the second half period of rice cultivation. A large fraction of Ga was accumulated in the rice roots, with only a small portion of Ga was transferred to the shoots and then to the rice grains. This study revealed that Ga speciation in soil-rice plant systems varied during rice cultivation and determined soil Ga availability to rice plants. Gallium accumulated in rice grains is distributed homogenously in the endosperm of the grains, suggesting a potential risk to public health via the intake of rice grains harvested from Ga-contaminated paddy fields.

Spectrophotometric and colorimetric determination of gallium (III) with p-aminohippuric acid-functionalized citrate capped gold nanoparticles

A new technique for sensing Ga(III) concentration based on polyvinyl alcohol-citrate capped gold nanoparticle– p- aminohippuric acid hybrid (or three-layer core-shell configurations) has been demonstrated. The p- aminohippuric acid capped citrate-gold nanoparticles were comfortably agglomerated in the presence of Ga(III), and the color of the reaction quickly turned from red to violet or blue. Under the detection conditions, a good linear relationship was ideally obtained between the ratio of the absorbance intensity at 620 nm to that at 520 nm (A₆₂₀/A₅₂₀). The linear response range, the detection, and quantification limit was 34.9–418.3 μg/L and 7.6 μg/L, and 25 μg/L, respectively. To reflect the accuracy, the developed sensing approach was evaluated against certified reference materials (TMDA 51.3 fortified water and TMDA 28.3 fortified water). This colorimetric strategy was displayed excellent selectivity for Ga(III) over other examined ions. Additionally, the colorimetric method was properly used to detect the concentrations of Ga in tap water and certified reference material samples with recoveries ranging from 95.4 to 102.0%, displaying that the colorimetric procedure could be safely used for a realistic application.

Arsenic: Various species with different effects on cytochrome P450 regulation in humans

Arsenic is well-recognized as one of the most hazardous elements which is characterized by its omnipresence throughout the environment in various chemical forms. From the simple inorganic arsenite (iAsIII) and arsenate (iAsV) molecules, a multitude of more complex organic species are biologically produced through a process of metabolic transformation with biomethylation being the core of this process. Because of their differential toxicity, speciation of arsenic-based compounds is necessary for assessing health risks posed by exposure to individual species or co-exposure to several species. In this regard, exposure assessment is another pivotal factor that includes identification of the potential sources as well as routes of exposure. Identification of arsenic impact on different physiological organ systems, through understanding its behavior in the human body that leads to homeostatic derangements, is the key for developing strategies to mitigate its toxicity. Metabolic machinery is one of the sophisticated body systems targeted by arsenic. The prominent role of cytochrome P450 enzymes (CYPs) in the metabolism of both endobiotics and xenobiotics necessitates paying a great deal of attention to the possible effects of arsenic compounds on this superfamily of enzymes. Here we highlight the toxicologically relevant arsenic species with a detailed description of the different environmental sources as well as the possible routes of human exposure to these species. We also summarize the reported findings of experimental investigations evaluating the influence of various arsenicals on different members of CYP superfamily using human-based models.

Comparison of the performance of atmospheric pressure glow discharges operated between a flowing liquid cathode and either a pin-type anode or a helium jet anode for the Ga and In determination by the optical emission spectrometry

Novel atmospheric pressure glow discharge (APGD) microplasma systems, sustained between a miniaturized flowing liquid cathode (FLC) and either a pin-type anode or a He nozzle jet were investigated for the determination of Ga and In by the optical emission spectrometry (OES). The most influential working parameters, i.e., solution flow rate, acid concentration, discharge current, and He flow rate, were optimized for both studied systems. Furthermore, the effect of the addition of low molecular weight organic compounds (LMWOCs) into the FLC solution on the signals intensity of Ga and In was investigated. Subsequently, the impact of concomitant ions on the signals intensity of Ga and In was thoroughly studied and it was established that both studied methods are relatively resistant to matrix effects. Under the optimized conditions, the detection limits (DLs, assessed on the basis of the 3σ criterion) of the studied elements were similar for both discharges and ranged between 1.8 and 2.3 μg L^-1 for Ga and 0.37-0.40 μg L^-1 for In. The received DLs were therefore better than those obtained for other spectrometric methods being premised upon microplasma systems and comparable with those obtained by currently employed large-scale instrumentation. The system with the pin-type anode was successfully applied for the Ga and In determination in four leachates of solders and electronic scrap as well as river water, using external calibration with simple standard solutions. The received results were compared to those obtained from ICP-OES or ICP-MS measurements and their recoveries were fallen within the range of 98-114%, confirming the excellent accuracy and reliability of the developed FLC-APGD-OES method.

Environmental contamination and public health effects of electronic waste: an overview

Purpose

In recent years, electronic waste has become the fastest growing waste stream globally with potential deleterious environmental and public health effects from its hazardous constituents. This review aims at providing an up-to-date information on the environmental and public health effects of e- wastes, and also identify research gaps that could form basis of further innovative studies on this important subject.

Methods

We carried out literature survey using several search engines. All available literature which reported directly on environmental contamination of air, soil, and water by e-wastes, and their effects on exposed plants, animals, and humans were used in other to generate an updated information.

Results

High production volume coupled with indiscriminate disposal and informal recycling has made electronic waste (e-waste) to become a global public and environmental health issue. E-waste is made up of different hazardous substances such as heavy metals and persistent organic pollutants with the capacity to contaminate the environment if processed or recycled inappropriately. Humans and animals become exposed to e-waste constituents via ingestion, inhalation, and dermal contact. Several health effects have been linked to e-wastes. The most susceptible were children, pregnant women, and workers in primitive recycling sites. Generation of e-waste is predicted to increase drastically in the next decade with the potential complex interactive effects of its constituents.

Conclusion

This review is an up-to-date assessment of studies and reports on e-waste environmental contamination and public health effects. The review has shown that e-waste contains constituents that caused adverse environmental effects and toxicity to the biota. However, there is an enormous data gap between exposure quantification and possible health effects. More studies are needed to elucidate and provide holistic information on environmental and public health dangers posed by e-waste constituents.

The growth and uptake of gallium (Ga) and indium (In) of wheat seedlings in Ga- and In-contaminated soils

The emerging contaminants gallium (Ga) and indium (In) are extensively used in advanced industries and are considered as toxic to humans. Limited information is available on the dynamics of Ga and In in soil-upland crop systems. Therefore, this study aimed to investigate the effects of Ga and In on the growth and uptake of Ga and In by wheat plants grown in Ga- and In-contaminated soils. The wheat seedlings were planted in soils of different properties spiked with various Ga and In concentrations (50, 100, 200, and 400 mg kg^-1). The plant-available Ga, In, and Al in the soils were extracted by 0.02 M CaCl₂, and their concentrations in plant tissues of wheat seedlings and plant biomass were determined after harvesting. The results indicated that the Al toxicity of wheat seedlings increased with Ga and In concentrations in acidic soils. Indium phytotoxicity was found in both neutral and acidic soils. Plant analysis results indicated that the concentration of Ga and In in roots was approximately one order of magnitude higher than that in the shoots of wheat seedlings, and the capability for Ga translocation from roots to shoots was higher than for In. The results of this study suggest that the dynamics of Ga and In in soil-upland crop systems is strongly dependent on the soil properties, such as pH and Al availability.

Workplace Emissions and Exposures During Semiconductor Nanowire Production, Post-production, and Maintenance Work

Background

Nanowires are a high-aspect-ratio material of increasing interest for a wide range of applications. A new and promising method to produce nanowires is by aerotaxy, where the wires are grown in a continuous stream of gas. The aerotaxy method can grow nanowires much faster than by more conventional methods. Nanowires have important properties in common with asbestos fibers, which indicate that there can be potential health effects if exposure occurs. No conclusive exposure (or emission) data from aerotaxy-production of nanowires has so far been published.

Methods

Different work tasks during semiconductor nanowire production, post-production, and maintenance were studied. A combination of direct-reading instruments for number concentration (0.007–20 µm) and filter sampling was used to assess the emissions (a couple of centimeter from the emission sources), the exposure in the personal breathing zone (max 30 cm from nose–mouth), and the concentrations in the background zone (at least 3 m from any emission source). The filters were analyzed for metal dust composition and number concentration of nanowires. Various surfaces were sampled for nanowire contamination.

Results

The particle concentrations in the emission zone (measured with direct-reading instruments) were elevated during cleaning of arc discharge, manual reactor cleaning, exchange of nanowire outflow filters, and sonication of substrates with nanowires. In the case of cleaning of the arc discharge and manual reactor cleaning, the emissions affected the concentrations in the personal breathing zone and were high enough to also affect the concentrations in the background. Filter analysis with electron microscopy could confirm the presence of nanowires in some of the air samples.

Conclusions

Our results show that a major part of the potential for exposure occurs not during the actual manufacturing, but during the cleaning and maintenance procedures. The exposures and emissions were evaluated pre- and post-upscaling the production and showed that some work tasks (e.g. exchange of nanowire outflow filters and sonication of substrates with nanowires) increased the emissions post-upscaling.

Enrichment Mechanisms of Gallium and Indium in No. 9 Coals in Anjialing Mine, Ningwu Coalfield, North China, with a Preliminary Discussion on Their Potential Health Risks

To provide a comprehensive insight into the enrichment mechanism of gallium and indium in No. 9 coals, eighteen samples were collected from Anjialing mine, Ningwu Coalfield, Shanxi Province for coal petrological, mineralogical and geochemical analyses. The results suggested that Ga and In enrichment mainly hosted in the top horizons, with average concentration coefficients of 8.99 and 2.73 respectively, compared with the rest of horizons (2.46 for Ga and 1.69 for In). Source apportionment indicated that Ga and In were mainly derived from bauxite of Benxi Formation in Yinshan Oldland, while In could originate from felsic magmatic rocks in Yinshan Oldland as well. In addition, weak oxidation condition, medium to intensive weathering, transgression and input of terrestrial higher plants had positive effects on Ga and In enrichment. With the rapid expansion of emerging electronics manufacturing, Ga and In, of which potential risks on human health were neglected previously, were recently considered as hazardous elements. Therefore, this paper also discussed the potential pathways that these elements threatened human health. We suggested that potential risks on environment and human health caused by Ga and In enrichment in coals and coal-related products should be taken into account besides their economic value.

Heteroepitaxial Growth of III-V Semiconductors on Silicon

Monolithic integration of III-V semiconductor devices on Silicon (Si) has long been of great interest in photonic integrated circuits (PICs), as well as traditional integrated circuits (ICs), since it provides enormous potential benefits, including versatile functionality, low-cost, large-area production, and dense integration. However, the material dissimilarity between III-V and Si, such as lattice constant, coefficient of thermal expansion, and polarity, introduces a high density of various defects during the growth of III-V on Si. In order to tackle these issues, a variety of growth techniques have been developed so far, leading to the demonstration of high-quality III-V materials and optoelectronic devices monolithically grown on various Si-based platform. In this paper, the recent advances in the heteroepitaxial growth of III-V on Si substrates, particularly GaAs and InP, are discussed. After introducing the fundamental and technical challenges for III-V-on-Si heteroepitaxy, we discuss recent approaches for resolving growth issues and future direction towards monolithic integration of III-V on Si platform.

A Thiourea-Containing Fluorescent Chemosensor for Detecting Ga3

A thiourea-based fluorescent chemosensor NADA, (E)-2-(4-(diethylamino)-2-hydroxybenzylidene)-N-(naphthalen-1-yl)hydrazine-1-carbothioamide, has been designed and synthesized. NADA could detect Ga³⁺ through a fluorescent turn-on with a low detection limit (0.29 μM). Importantly, NADA could effectively discriminate Ga³⁺ from Al³⁺ and In³⁺. The binding mechanism of NADA with Ga³⁺ was identified by ESI-mass, NMR titration, and DFT calculations.

Influence of humic substances on the transport of indium and gallium in porous media

Indium and gallium are used widely in modern industry, mostly for the production of semiconductors. They are considered as Technology-Critical Elements and have therefore received growing attention in the past few years. We investigated the influence of different types of humic substances on the transport of indium and gallium in laboratory-scale, saturated column experiments, to gain understanding of their mobility in natural environments. We evaluated the effect of different humic substances on the transport of indium and gallium in quartz sand: a commercial humic acid (Aldrich Humic Acid, AHA), a fulvic acid (Suwannee River Fulvic Acid, SRFA) and an aquatic natural organic matter (Suwannee River Natural Organic Matter, SRNOM). The impact of the flow rate and the influence of different concentrations of organic matter were also investigated. Indium was shown to be more mobile than gallium in the presence of humic substances. The mobility of indium in sand was highest for SRNOM, followed by SRFA and then AHA, while for gallium the order was SRFA > SRNOM > AHA. These results can be significant in understanding the mobility of indium and gallium in soils with various compositions of organic matter.

Accumulation of gallium (Ga) and indium (In) in rice grains in Ga- and In-contaminated paddy soils

To understand the risk of two emerging contaminants, gallium (Ga) and indium (In) to humans via rice consumption, effects of soil properties and concentrations of spiked Ga/In on the accumulation of Ga and In in rice grains were investigated. A pot experiment was conducted, and paddy rice was grown in three soils with different pH values and Al availabilities (i.e., Pc, TWz and Cf), which were spiked with various Ga and In concentrations. The growth index and concentrations of Ga, In, and Al in plant tissues and soil pore water were measured. Results revealed that the concentrations of Ga and In in soil pore water increase with the spiking of Ga or In in all of the tested soils, but the biomass of roots and shoots does not significantly decrease. The accumulation of Ga in shoots and brown rice was significantly reduced in high available Al acidic soils (Pc soils), but this accumulation was significantly increased in low available Al acidic soils (TWz soils), which can be explained by the competitive uptake between Ga and Al by rice plants. The extent of competitive effects between In and Al was less than that between Ga and Al because of the lower solubility and translocation capability of In than those of Ga in soil-rice systems. However, significant differences in the concentrations of Ga and In in brown rice in neutral soils (Cf soils) among the Ga or In treatment were not observed. In addition, the iron plaque formed on the root surface can serve as a barrier to reduce the accumulation of Ga in rice plants. This study suggested that the risk of accumulation of Ga and In in rice grains should be of concern when paddy rice is grown in acidic Ga- or In-contaminated soils with low Al availability.

Physiological status and functional anatomy of zebra fish (Danio rerio) exposed to various levels of Ga3

Gallium (Ga) is one of the intermetallic elements that has been used in cancer treatment for a long time. However, Ga compounds are increasingly being used to make high-speed semiconductors and photoelectric devices. The current work investigated physiological and pathological changes in zebra fish (Danio rerio) exposed to various Ga³⁺ levels (0.55, 1.5, and 3.85 mg/L) over a 14-day test period. Decreases in oxygen consumption were significant (p < 0.05) for groups exposed to 3.85 Ga³⁺ mg/L; this was associated with the fusion of zebra fish gills lamellae. Serum biochemical changes (including aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase) were consistent with observations of damage to organelles within the hepatocytes at higher Ga³⁺ exposure levels (1.5 and 3.85 mg/L) in zebra fish. We propose <0.55 Ga³⁺ mg/L as a biologically safe concentration that can be used to establish water quality criteria for this teleost model.

Lanthanum, Gallium and their Impact on Oxidative Stress

The role metals play in living organisms is well established and subject to extensive research. Some of them participate in electron-exchange reactions. Such reactions cause generation of free radicals that can adversely impact biological systems, as a result of oxidative stress. The impact of 'non-biological' metals on oxidative stress is also a worthy pursuit due to the crucial role they play in modern civilization. Lanthanides (Ln) are widely used in modern technology. As a result, human exposure to them is increasing. They have a number of established medical applications and are being extensively researched for their potential antiviral, anticancer and anti-inflammatory properties. The present review focuses on lanthanum (La) and its impact on oxidative stress. Another metal, widely used in modern high-tech is gallium (Ga). In some respects, it shows certain similarities to La, therefore it is a subject of the present review as well. Both metals exhibit ionic mimicry which allows them to specifically target malignant cells, initiating apoptosis that makes their simple salts and coordination complexes promising candidates for future anticancer agents.

Microbial toxicity of gallium- and indium-based oxide and arsenide nanoparticles

III-V semiconductor materials such as gallium arsenide (GaAs) and indium arsenide (InAs) are increasingly used in the fabrication of electronic devices. There is a growing concern about the potential release of these materials into the environment leading to effects on public and environmental health. The waste effluents from the chemical mechanical planarization process could impact microorganisms in biological wastewater treatment systems. Currently, there is only limited information about the inhibition of gallium- and indium-based nanoparticles (NPs) on microorganisms. This study evaluated the acute toxicity of GaAs, InAs, gallium oxide (Ga₂O₃), and indium oxide (In₂O₃) particulates using two microbial inhibition assays targeting methanogenic archaea and the marine bacterium, Aliivibrio fischeri. GaAs and InAs NPs were acutely toxic towards these microorganisms; Ga₂O₃ and In₂O₃ NPs were not. The toxic effect was mainly due to the release of soluble arsenic species and it increased with decreasing particle size and with increasing time due to the progressive corrosion of the NPs in the aqueous bioassay medium. Collectively, the results indicate that the toxicity exerted by the arsenide NPs under environmental conditions will vary depending on intrinsic properties of the material such as particle size as well as on the dissolution time and aqueous chemistry.

Completely Solvent-free Protocols to Access Phase-Pure, Metastable Metal Halide Perovskites and Functional Photodetectors from the Precursor Salts

Mechanochemistry is a green, solid-state, re-emerging synthetic technique that can rapidly form complex molecules and materials without exogenous heat or solvent(s). Herein, we report the application of solvent-free mechanochemical ball milling for the synthesis of metal halide perovskites, to overcome problems with solution-based syntheses. We prepared phase-pure, air-sensitive CsSnX3 (X = I, Br, Cl) and its mixed halide perovskites by mechanochemistry for the first time by reactions between cesium and tin(II) halides. Notably, we report the sole examples where metastable, high-temperature phases like cubic CsSnCl3, cubic CsPbI3, and trigonal FAPbI3 were accessible at ambient temperatures and pressures without post-synthetic processing. The perovskites can be prepared up to "kilogram scales." Lead-free, all-inorganic photodetector devices were fabricated using the mechanosynthesized CsSnBr1.5Cl1.5 under solvent-free conditions and showed 10-fold differences between on-off currents. We highlight an essentially solvent-free, general approach to synthesize metastable compounds and fabricate photodetectors from commercially available precursors.

Demonstration of a Robust All-Silicon-Carbide Intracortical Neural Interface

Intracortical neural interfaces (INI) have made impressive progress in recent years but still display questionable long-term reliability. Here, we report on the development and characterization of highly resilient monolithic silicon carbide (SiC) neural devices. SiC is a physically robust, biocompatible, and chemically inert semiconductor. The device support was micromachined from p-type SiC with conductors created from n-type SiC, simultaneously providing electrical isolation through the resulting p-n junction. Electrodes possessed geometric surface area (GSA) varying from 496 to 500 K μm². Electrical characterization showed high-performance p-n diode behavior, with typical turn-on voltages of ~2.3 V and reverse bias leakage below 1 nArms. Current leakage between adjacent electrodes was ~7.5 nArms over a voltage range of -50 V to 50 V. The devices interacted electrochemically with a purely capacitive relationship at frequencies less than 10 kHz. Electrode impedance ranged from 675 ± 130 kΩ (GSA = 496 µm²) to 46.5 ± 4.80 kΩ (GSA = 500 K µm²). Since the all-SiC devices rely on the integration of only robust and highly compatible SiC material, they offer a promising solution to probe delamination and biological rejection associated with the use of multiple materials used in many current INI devices.

Sensors for Fetal Hypoxia and Metabolic Acidosis: A Review

This article reviews existing clinical practices and sensor research undertaken to monitor fetal well-being during labour. Current clinical practices that include fetal heart rate monitoring and fetal scalp blood sampling are shown to be either inadequate or time-consuming. Monitoring of lactate in blood is identified as a potential alternative for intrapartum fetal monitoring due to its ability to distinguish between different types of acidosis. A literature review from a medical and technical perspective is presented to identify the current advancements in the field of lactate sensors for this application. It is concluded that a less invasive and a more continuous monitoring device is required to fulfill the clinical needs of intrapartum fetal monitoring. Potential specifications for such a system are also presented in this paper.

Exposure Potential and Health Impacts of Indium and Gallium, Metals Critical to Emerging Electronics and Energy Technologies

The rapid growth of new electronics and energy technologies requires the use of rare elements of the periodic table. For many of these elements, little is known about their environmental behavior or human health impacts. This is true for indium and gallium, two technology critical elements. Increased environmental concentrations of both indium and gallium create the potential for increased environmental exposure, though little is known about the extent of this exposure. Evidence is mounting that indium and gallium can have substantial toxicity, including in occupational settings where indium lung disease has been recognized as a potentially fatal disease caused by the inhalation of indium particles. This paper aims to review the basic chemistry, changing environmental concentrations, potential for human exposure, and known health effects of indium and gallium.

Development of a selective and sensitive Ga3+ sensor for environmental safety: a comparative study of cyclohexyl and aromatic bis-sulphonamide fabricated glassy carbon electrodes

The aim of this study was to synthesize the new chelating agents CDBDMBS and PBDMBD for environmental remediation by sensing of Ga³⁺ in aqueous solution. The electrochemical technique is introduced a new approach of development of cost effective toxic cationic sensors for environmental and healthcare fields.

A multifunctional selective “turn-on” fluorescent chemosensor for detection of Group IIIA ions Al3+, Ga3+ and In3+

A versatile chemosensor was developed for highly distinguishable and selective recognition of group IIIA metal ions (Al³⁺, Ga³⁺ and In³⁺).

Effect of Gallium Exposure in Arabidopsis thaliana is Similar to Aluminum Stress

Although gallium (Ga) is a rare element, it is widely used in semiconductor devices. Ga contamination of the environment has been found in semiconductor-producing countries. Here, the physiological and molecular impacts of Ga in the model plant Arabidopsis thaliana were investigated in medium culture. The primary symptom of Ga toxicity is inhibition of root growth. The increased production of malondialdehyde (MDA) suggests that Ga stress could cause oxidative damage in plants. Roots were the main Ga accumulating sites. The distinctive Ga granules were deposited within the intercellular space in roots. The granules are Ga(OH)₃ precipitation, which indicates immobilization or limited translocation of Ga in A. thaliana. Ga stress induces root secretion of organic acids such as citrate and malate. The expression of the transporters AtALMT and AtMATE, responsible for citrate and malate secretion, respectively, were elevated under Ga stress, so the secretion may play a role in the resistance. Indeed, supplying exogenous citrate significantly enhanced Ga tolerance. The overall response to Ga exposure in A. thaliana is highly similar to that with aluminum stress. Our findings provide information for risk assessment in Ga-contaminated soil.

Solubility of indium-tin oxide in simulated lung and gastric fluids: Pathways for human intake

From being a metal with very limited natural distribution, indium (In) has recently become disseminated throughout the human society. Little is known of how In compounds behave in the natural environment, but recent medical studies link exposure to In compounds to elevated risk of respiratory disorders. Animal tests suggest that exposure may lead to more widespread damage in the body, notably the liver, kidneys and spleen. In this paper, we investigate the solubility of the most widely used In compound, indium-tin oxide (ITO) in simulated lung and gastric fluids in order to better understand the potential pathways for metals to be introduced into the bloodstream. Our results show significant potential for release of In and tin (Sn) in the deep parts of the lungs (artificial lysosomal fluid) and digestive tract, while the solubility in the upper parts of the lungs (the respiratory tract or tracheobronchial tree) is very low. Our study confirms that ITO is likely to remain as solid particles in the upper parts of the lungs, but that particles are likely to slowly dissolve in the deep lungs. Considering the prolonged residence time of inhaled particles in the deep lung, this environment is likely to provide the major route for uptake of In and Sn from inhaled ITO nano- and microparticles. Although dissolution through digestion may also lead to some uptake, the much shorter residence time is likely to lead to much lower risk of uptake.

The growth and uptake of Ga and In of rice (Oryza sative L.) seedlings as affected by Ga and In concentrations in hydroponic cultures

Limited information is available on the effects of gallium (Ga) and indium (In) on the growth of paddy rice. The Ga and In are emerging contaminants and widely used in high-tech industries nowadays. Understanding the toxicity and accumulation of Ga and In by rice plants is important for reducing the effect on rice production and exposure risk to human by rice consumption. Therefore, this study investigates the effect of Ga and In on the growth of rice seedlings and examines the accumulation and distribution of those elements in plant tissues. Hydroponic cultures were conducted in phytotron glasshouse with controlled temperature and relative humidity conditions, and the rice seedlings were treated with different levels of Ga and In in the nutrient solutions. The growth index and the concentrations of Ga and In in roots and shoots of rice seedlings were measured after harvesting. A significant increase in growth index with increasing Ga concentrations in culture solutions (<10mgGaL^-1) was observed. In addition, the uptake of N, K, Mg, Ca, Mn by rice plants was also enhanced by Ga. However, the growth inhibition were observed while the In concentrations higher than 0.08mgL^-1, and the nutrients accumulated in rice plants were also significant decreased after In treatments. Based on the dose-response curve, we observed that the EC₁₀ (effective concentration resulting in 10% growth inhibition) value for In treatment was 0.17mgL^-1. The results of plant analysis indicated that the roots were the dominant sink of Ga and In in rice seedlings, and it was also found that the capability of translocation of Ga from roots to shoots were higher than In. In addition, it was also found that the PT₁₀ (threshold concentration of phytotoxicity resulting in 10% growth retardation) values based on shoot height and total biomass for In were 15.4 and 10.6μgplant^-1, respectively. The beneficial effects on the plant growth of rice seedlings were found by the addition of Ga in culture solutions. In contrast, the In treatments led to growth inhibition of rice seedlings. There were differences in the phytotoxicity, uptake, and translocation of the two emerging contaminants in rice seedlings.

Determination of mutagenicity and genotoxicity of indium tin oxide nanoparticles using the Ames test and micronucleus assay

In this study, the mutagenicity and genotoxicity of indium tin oxide (ITO) nanomaterial were assessed using two standard genotoxicity assays, the Salmonella reverse mutation assay (Ames test) and the in vitro micronucleus (MN) assay. Seven different concentrations (12.5, 25, 50, 75, 100, 125, and 150 µg/plate) of this nanomaterial were tested using the Ames test on the TA98 and TA100 strains in the presence and absence of the S9 mixture. At all the concentrations tested, this substance did not significantly increase the number of revertant colonies compared with the control with or without S9 mixture. The genotoxic effects of ITO were investigated in human peripheral lymphocytes treated with 125, 250, 500, and 750 µg/ml concentrations of this substance for 24- and 48-h treatment periods using an MN test. Nuclear division index (NDI) was also calculated in order to determine the cytotoxicity of ITO. It was determined that ITO increased MN frequency in the 750 µg/ml concentration in 24- and 48-h treatments. In addition, ITO dose dependently decreased the NDI significantly for two treatment periods.

Potential resource and toxicity impacts from metals in waste electronic devices

As a result of the continuous release of new electronic devices, existing electronic devices are quickly made obsolete and rapidly become electronic waste (e-waste). Because e-waste contains a variety of metals, information about those metals with the potential for substantial environmental impact should be provided to manufacturers, recyclers, and disposers to proactively reduce this impact. This study assesses the resource and toxicity (i.e., cancer, noncancer, and ecotoxicity) potentials of various heavy metals commonly found in e-waste from laptop computers, liquid-crystal display (LCD) monitors, LCD TVs, plasma TVs, color cathode ray tube (CRT) TVs, and cell phones and then evaluates such potentials using life cycle impact-based methods. Resource potentials derive primarily from Cu, Sb, Ag, and Pb. Toxicity potentials derive primarily from Pb, Ni, and Hg for cancer toxicity; from Pb, Hg, Zn, and As for noncancer toxicity; and from Cu, Pb, Hg, and Zn for ecotoxicity. Therefore, managing these heavy metals should be a high priority in the design, recycling, and disposal stages of electronic devices.

Utility of solid phase extraction for UV-visible spectrophotometric determination of gallium in environmental and biological samples

Absorption spectra for 2 × 10⁻⁵ M BTAHN complexed with 0.5 μg mL⁻¹ Ga(III) at the optimum conditions.

Indium acetate toxicity in male reproductive system in rats

Indium, a rare earth metal characterized by high plasticity, corrosion resistance, and a low melting point, is widely used in the electronics industry, but has been reported to be an environmental pollutant and a health hazard. We designed a study to investigate the effects of subacute exposure of indium compounds on male reproductive function. Twelve-week old male Sprague-Dawley rats were randomly divided into test and control groups, and received weekly intraperitoneal injections of indium acetate (1.5 mg/kg body weight) and normal saline, respectively, for 8 weeks. Serum indium levels, cauda epididymal sperm count, motility, morphology, chromatin DNA structure, mitochondrial membrane potential, oxidative stress, and testis DNA content were investigated. The indium acetate-treated group showed significant reproductive toxicity, as well as an increased percentage of sperm morphology abnormality, chromatin integrity damage, and superoxide anion generation. Furthermore, positive correlations among sperm morphology abnormalities, chromatin DNA damage, and superoxide anion generation were also noted. The results of this study demonstrated the toxic effect of subacute low-dose indium exposure during the period of sexual maturation on male reproductive function in adulthood, through an increase in oxidative stress and sperm chromatin DNA damage during spermiogenesis, in a rodent model.

Implications of the Differential Toxicological Effects of III-V Ionic and Particulate Materials for Hazard Assessment of Semiconductor Slurries

Because of tunable band gaps, high carrier mobility, and low-energy consumption rates, III-V materials are attractive for use in semiconductor wafers. However, these wafers require chemical mechanical planarization (CMP) for polishing, which leads to the generation of large quantities of hazardous waste including particulate and ionic III-V debris. Although the toxic effects of micron-sized III-V materials have been studied in vivo, no comprehensive assessment has been undertaken to elucidate the hazardous effects of submicron particulates and released III-V ionic components. Since III-V materials may contribute disproportionately to the hazard of CMP slurries, we obtained GaP, InP, GaAs, and InAs as micron- (0.2-3 μm) and nanoscale (<100 nm) particles for comparative studies of their cytotoxic potential in macrophage (THP-1) and lung epithelial (BEAS-2B) cell lines. We found that nanosized III-V arsenides, including GaAs and InAs, could induce significantly more cytotoxicity over a 24-72 h observation period. In contrast, GaP and InP particulates of all sizes as well as ionic GaCl3 and InCl3 were substantially less hazardous. The principal mechanism of III-V arsenide nanoparticle toxicity is dissolution and shedding of toxic As(III) and, to a lesser extent, As(V) ions. GaAs dissolves in the cell culture medium as well as in acidifying intracellular compartments, while InAs dissolves (more slowly) inside cells. Chelation of released As by 2,3-dimercapto-1-propanesulfonic acid interfered in GaAs toxicity. Collectively, these results demonstrate that III-V arsenides, GaAs and InAs nanoparticles, contribute in a major way to the toxicity of III-V materials that could appear in slurries. This finding is of importance for considering how to deal with the hazard potential of CMP slurries.

Phytotoxicity and Transport of Gallium (Ga) in Rice Seedlings for 2-Day of Exposure

Hydroponic experiments were conducted with rice seedlings to investigate the accumulation and phytotoxicity of gallium nitrate. A linear decrease in relative growth rate, transpiration rate and water use efficiency was observed in rice seedlings with increasing Ga concentrations. However, inhibition of these selected parameters was noted different at different Ga treatments. Relative growth rate was more sensitive towards Ga treatments. Phyto-transport of Ga was apparent, but recovery of Ga in different parts of rice seedlings varied significantly: roots were dominant site for Ga accumulation. The total accumulation rates of Ga were positively correlated to Ga concentrations. Results indicated that the addition of Ga did not cause deleterious effects on plant physiological functions over a 2-day exposure period. Large amounts of Ga were removed from the hydroponic solution through rice seedlings. Accumulation of Ga in plant tissues resulted in growth inhibition of rice seedlings.

DNA-protein cross-links involved in growth inhibition of rice seedlings exposed to Ga

Hydroponic experiments were conducted with rice seedlings (Oryza sativa L. cv. XZX45) exposed to gallium nitrate (Ga(3+)) to investigate the accumulation of Ga in plant tissues and phytotoxic responses. Results showed that phyto-transport of Ga was apparent, and roots were the dominant site for Ga accumulation. The total accumulation rates of Ga responded biphasically to Ga treatments by showing increases at low (1.06-8.52 mg Ga/L) and constants at high (8.52-15.63 mg Ga/L) concentrations, suggesting that accumulation kinetics of Ga followed a typical saturation curve. Higher amount of Ga accumulation in plant tissues led to significant inhibition in relative growth rate and water use efficiency in a dose-dependent manner. DNA-protein cross-links (DPCs) analysis revealed that overaccumulation of Ga in plant tissues positively stimulated formation of DPCs in roots. Likewise, the measure of root cell viability evaluated by Evan blue uptake showed a similar trend. These results suggested that Ga can be absorbed, transported, and accumulated in plant materials of rice seedlings. Overaccumulation of Ga in plant tissues provoked the formation of DPCs in roots, which resulted in cell death and growth inhibition of rice seedlings.

Engineering the cell-semiconductor interface: a materials modification approach using II-VI and III-V semiconductor materials

Developing functional biomedical devices based on semiconductor materials requires an understanding of interactions taking place at the material-biosystem interface. Cell behavior is dependent on the local physicochemical environment. While standard routes of material preparation involve chemical functionalization of the active surface, this review emphasizes both biocompatibility of unmodified surfaces as well as use of topographic features in manipulating cell-material interactions. Initially, the review discusses experiments involving unmodified II-VI and III-V semiconductors - a starting point for assessing cytotoxicity and biocompatibility - followed by specific surface modification, including the generation of submicron roughness or the potential effect of quantum dot structures. Finally, the discussion turns to more recent work in coupling topography and specific chemistry, enhancing the tunability of the cell-semiconductor interface. With this broadened materials approach, researchers' ability to tune the interactions between semiconductors and biological environments continues to improve, reaching new heights in device function.