The ornamental pet trade is often considered a key culprit for conservation problems such as the introduction of invasive species (including infectious diseases) and overharvesting of rare species. Here, we present the first assessment of the biodiversity of freshwater molluscs in the ornamental pet trade in Singapore, one of the most important global hubs of the ornamental aquarium trade, and discuss associated conservation concerns. We recorded freshwater molluscs from ornamental pet shops and major exporters including non-ornamental species (e.g., hitchhikers, molluscs sold as fish feed). We recorded an unexpectedly high diversity—59 species—of freshwater bivalves and gastropods, with the majority (38 species or 64%) being from the Oriental region. In addition to morphological examination, we sequenced the DNA barcode region of mitochondrial CO1 and 16S genes to provide molecular data for the confirmation of the identification and for future re-identification. DNA barcodes were obtained for 50 species, and all but four were separated by > 3% uncorrected pairwise distances. The trade has been considered a main introduction pathway for non-native species to Singapore, and we found that out of 15 species in the trade as well as in the wild in Singapore, 12 are either introduced or of unknown origin, representing almost half of the known non-native freshwater molluscs in Singapore. Particularly prevalent are non-ornamental species: six hitchhikers on aquarium plants and six species sold as fish feed. We found that a quarter of the trade species have a history of introduction, which includes 11 known or potentially invasive species. We conclude that potential overharvesting is difficult to assess because only half of the trade species have been treated by IUCN. Of these, 21 species are of Least Concern and three are Data Deficient. Our checklist, with accompanying DNA barcodes, images, and museum vouchers, provides an important reference library for future monitoring, and constitutes a step toward creating a more sustainable ornamental pet trade.

Conductance-voltage (G-V) analyses were performed on trilayer germanium (Ge) nanocrystal memory capacitor structures, consisting of a high dielectric constant (high-κ) layer (5nm thick) grown on silicon, a sputtered Ge middle layer (4nm thick), and a 20nm thick sputtered cap oxide layer (either SiO2 for moderate gate electric field coupling or HfAlOx for better electric field coupling). Comparisons of the G-V characteristics were performed with a control capacitor sample without nanocrystals. The distinctive characteristics due to nanocrystals could be separated and identified from the interface traps provided the memory structure has sufficiently high electric field coupling from the gate applied voltage, resulting in a large electric field across the tunnel dielectric layer. This work attempts to provide an explanation to the G-V characteristics under the following three conditions: (1) interface trap dominated, (2) nanocrystal dominated, and (3) a combination of effects from both interface traps and nanocrystals. A method for estimating the density of nanocrystals based on the G-V data is also described.

We report on the structural and vibrational characterization of silicon (Si) nanowire arrays synthesized by metal-assisted chemical etching (MACE) of Si deposited with metal nanoparticles. Gold (Au) and silver (Ag) metal nanoparticles were synthesized by glancing angle deposition, and MACE was performed in a mixture of H2O2 and HF solution. We studied the structural differences between Au and Ag-etched Si nanowires. The morphology of the synthesized nanowires was characterized by scanning electron microscopy and transmission electron microscopy. The optical and vibrational properties of the Si nanostructures were studied by photoluminescence and Raman spectroscopy using three different excitation sources (UV, visible, and near-infrared) and are correlated to their microstructures. The structural differences between Au-etched and Ag-etched nanowires are due to the higher degree of hole injection by the Au nanoparticle and diffusion into the Si nanowires, causing enhanced Si etching by HF on the nanowire surface. Au-etched nanowires were observed to be mesoporous throughout the nanowire while Ag-etched nanowires consisted of a thin porous layer around the crystalline core. In addition, the surface-enhanced resonant Raman scattering observed is attributed to the presence of the sunken metal nanoparticles. Such Si nanostructures may be useful for a wide range of applications such as photovoltaic and biological and chemical sensing.

Southeast Asia has the highest rate of deforestation among all tropical regions in the world. Depending on the number of undiscovered species not yet known to science, a sizeable proportion of species may have gone extinct or will go extinct in the future without record. We compiled species datasets for eight taxa, each consisting of a list of native species and their description dates. Birds, legumes, mosquitoes, and mosses showed recent declines in species discovery rate. For these taxa, we estimated the total species richness by applying generalized linear models derived from theory. The number of undiscovered species in each taxon was calculated and the extent of undiscovered species among the taxa compared. Among these taxa that displayed a species discovery decline, the legumes had the highest extent of undiscovered species while the birds had the most complete species inventory. Although quantitative estimates of the number of undiscovered species for amphibians, freshwater fish, hawkmoths, and mammals could not be derived, the extent of undiscovered species is likely to be high as their recent discovery rates showed a continued increase. If these taxa are more or less representative of other Southeast Asian taxa, many species are likely to go extinct before ever being discovered by science under the current rates of habitat loss. We therefore urge the intensification of taxonomic and species discovery research in the taxa in which the extent of undiscovered species is relatively high, i.e., amphibians, freshwater fish, hawkmoths, mammals, and legumes.

Summary 1.Identifying the ecological and life-history correlates of local extinction may elucidate mechanisms by which species traits and the environment interact to result in extinctions, and will help to predict and target extinction-prone species for inclusion in conservation programmes. Freshwater habitats are known to be highly threatened in Southeast Asia but the correlates of extinction among tropical freshwater fish remains unclear. 2. To bridge this knowledge gap, we examined extinction correlates of the freshwater fish of Singapore using machine learning methods: conditional inference trees and forests. Singapore is an ideal study site as it has experienced a high degree of habitat loss and has a well-studied ichthyofauna compared with other countries in the region. 3. The local range of a species was the only significant predictor of extinctions: range-restricted species were more likely to go extinct. 4. Other traits found to be important predictors of extinction risk in temperate regions or hypothesized to predict extinctions based on theory included regional geographic distribution, vertical position, feeding guild, body size, number of congeners, air-breathing capability and habitat preference. These factors did not appear to drive extinctions of freshwater fish in Singapore, although forest-dependent species are more likely to have a restricted local range. 5. Synthesis and applications. Local extinctions of freshwater fish in Singapore are random with respect to ecological and life-history traits because habitat loss is responsible for the removal of entire populations. The fish fauna of Southeast Asia is so poorly known that intensive field surveys are required to identify hotspots of freshwater fish endemism which may be vulnerable to future extinction. These hotspots should then be incorporated into national conservation plans. Where complete habitat protection is not possible, for example, in existing logging concessions and plantations, local authorities should establish partnerships with management companies to ameliorate impacts on fish fauna. Within Singapore, the Nee Soon Swamp Forest is one such hotspot of fish endemism and must be conserved to protect the last populations of five fish species endemic to this location on the island.

Magnetic resonance (MR) imaging (MRI) provides compelling features for the guidance of interventional procedures, including high-contrast soft tissue imaging, detailed visualization of physiological changes, and thermometry. Laser-based tumor ablation stands to benefit greatly from MRI guidance because 3D resection margins alongside thermal distributions can be evaluated in real time to protect critical structures while ensuring adequate resection margins. However, few studies have investigated the use of projection-based lasers like those for transoral laser microsurgery, potentially because dexterous laser steering is required at the ablation site, raising substantial challenges in the confined MRI bore and its strong magnetic field. Here, we propose an MR-safe soft robotic system for MRI-guided transoral laser microsurgery. Owing to its miniature size (Ø12 × 100 mm), inherent compliance, and five degrees of freedom, the soft robot ensures zero electromagnetic interference with MRI and enables safe and dexterous operation within the confined oral and pharyngeal cavities. The laser manipulator is rapidly fabricated with hybrid soft and hard structures and is powered by microvolume (<0.004 milliter) fluid flow to enable laser steering with enhanced stiffness and lowered hysteresis. A learning-based controller accommodates the inherent nonlinear robot actuation, which was validated with laser path–following tests. Submillimeter laser steering accuracy was demonstrated with a mean error < 0.20 mm. MRI compatibility testing demonstrated zero observable image artifacts during robot operation. Ex vivo tissue ablation and a cadaveric head-and-neck trial were carried out under MRI, where we employed MR thermometry to monitor the tissue ablation margin and thermal diffusion intraoperatively.

The Tonle Sap Lake in Cambodia is a crucial freshwater biodiversity hotspot and supports one of the world’s largest inland fisheries. Within the Tonle Sap basin, freshwater molluscs provide vital ecosystem services and are among the fauna targetted for commercial harvesting. Despite their importance, freshwater molluscs of the Tonle Sap basin remain poorly studied. The historical literature was reviewed and at least 153 species of freshwater molluscs have been previously recorded from throughout Cambodia, including 33 from the Tonle Sap basin. Surveys of the Tonle Sap Lake and surrounding watershed were also conducted and found 31 species, 15 bivalves (five families) and 16 gastropods (eight families), in the Tonle Sap basin, including three new records for Cambodia (Scaphula minuta, Novaculina siamensis, Wattebledia siamensis), the presence of globally invasive Pomacea maculata and potential pest species like Limnoperna fortunei. This study represents the most comprehensive documentation of freshwater molluscs of the Tonle Sap basin, and voucher specimens deposited at the Inland Fisheries Research and Development Institute, Cambodia, represent the first known reference collection of freshwater molluscs in the country. In order to combat the combined anthropogenic pressures, including invasive species, climate change and dams along the Mekong River, a multi-pronged approach is urgently required to study the biodiversity, ecology, ecosystem functioning of freshwater molluscs and other aquatic fauna in the Tonle Sap basin.

Ultra-low-k time-dependent dielectric breakdown (TDDB) is one of the most important reliability issues in Cu/low-k technology development due to its weaker intrinsic breakdown strength compared to SiO2 dielectrics. With continuous technology scaling, this problem is further exacerbated for Cu/ultra-low-k interconnects. In this letter, the TDDB degradation behavior of ultra-low-k dielectric in Cu/ultra-low-k interconnects will be investigated by a method consisting of a combination of Raman with Fourier transform infrared vibrational microscopes. In TDDB tests on Cu/low-k interconnect, it was found that intrinsic degradation of the ultra-low-k dielectric would first occur under electrical field stress. Upon further electrical field stress, the ultra-low-k dielectric degradation would be accelerated due to Ta ions migration from the Ta/TaN barrier bi-layer into the ultra-low-k dielectrics. In addition, no out-diffusion of Cu ions was observed in our investigation on Cu/Ta/TaN/SiCOH structures.