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The intestinal retention and persistence of lactic acid bacteria (LAB) are strain-specific and affected by the bacterial surface components. However, the contribution of surface adhesins of LAB to intestinal adhesion and colonization remains unclear. In the present study, seven gene knockout mutants (genes related to surface adhesin synthesis) of Lacticaseibacillus paracaseiS-NB were derived based on the Cre-lox-based recombination system. Results showed that the capsule layer appeared thinner in the cell wall of S-NBΔ7576, S-NBΔdlt, and S-NBΔsrtAmutants when compared with the wild-type (WT) S-NB. The effects of S-NB_7576 (wzdand wzegenes, responsible for capsular polysaccharide synthesis) and S-NB_srtA(sortase A) mutation on the hydrophobicity, surface charge, and adhesion ability seem to vary strongly among seven mutant strains. In vivo colonization experiments showed a decrease in the colonization numbers of S-NBΔ7576 and S-NBΔsrtAin both the ileal and colon lumen from 2 to 8 days when compared with those of the WT S-NB. In conclusion, the synthesis of capsular polysaccharides and the transport of surface proteins are closely related to the adhesion ability and intestinal colonization of L. paracaseiS-NB.

With the wide application of lithium-ion batteries (LIBs) in different fields, safety accidents occur frequently. Therefore, it is necessary to monitor the thermal runaway gas for an early warning. In this article, the adsorption properties of the characteristic gases of LIBs thermal runaway gases are studied by density functional theory (DFT). The adsorption structure of TM (Co/Rh/Ir)-decorated HfS2(TM@HfS2) is established, and its adsorption properties for C2H4, CH4, and CO are studied. The adsorption energy, charge transfer, band, DOS, charge difference density, work function, and recovery time are discussed in detail. The results show that Ir@HfS2has the strongest adsorption performance for C2H4and CO, so C2H4and CO can be stably adsorbed on the surface of the Ir@HfS2monolayer. The adsorption energy of CH4on Co@HfS2is stronger than those of Rh@HfS2and Ir@HfS2, but the adsorption energy is still very small. By applying biaxial strain to Co@HfS2, we found that the adsorption energy increases with the increase in negative strain. This study provides a theoretical basis for the regulation of the adsorption properties of HfS2by different transition metals.

Bio-synthesized nanoparticles (NPs) having reduced chemical toxicity have been focused globally and become essential component of nanotechnology recently. In the study reported here, silver/iron oxide nanocomposite (Ag/Fe2O3) was biosynthesized from ginger oil via a green, economic, and eco-friendly strategy. The biosynthesized Ag/Fe2O3were characterized using ultraviolet visible (UV–Vis), Fourier transform infrared (FTIR), X-ray diffraction (XRD), transmission electron microscope (TEM), dynamic light scattering (DLS), and scanning electron microscope/energy-dispersive X-ray (SEM–EDX) analysis. The particulates showed a spherical-morphology and had sizes between 44 and 200 nm. Ag/Fe2O3FTIR analysis revealed functional groups that were analogous to organic metabolites, which reduced and stabilized the nanocomposite. Antimicrobial efficacy of the biosynthesized Ag/Fe2O3against bacterial pathogens was assessed. In addition, Ag/Fe2O3exhibited broad spectrum activities against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosawith inhibition zones 22.6 ± 1.15, 21.1 ± 1.44, 18 ± 1 and 17.4 ± 2.67 mm, respectively. The Ag/Fe2O3showed promising antibacterial action against human bacterial pathogens, making them useful in the medical field.

In this study, DFT calculations are used to analyze the adsorption of industrial waste gases (NO2, SO2, H2S, and NH3) on WSe2monolayers. The adsorption energy, energy band, density of states, charge transfer, and recovery time of the adsorption structures between the target gas molecules and the Os-doped WSe2are studied. Compared with pure WSe2monolayer, Os surface bonding doping WSe2(Os-modified WSe2) and Os doping with Se vacancy of WSe2(Os-embedded WSe2) exhibit improved gas molecule adsorption ability. Among them, the adsorption energy of the Os-modified WSe2monolayer on NO2, SO2, H2S, and NH3is greater than that of the WSe2monolayer. At the same time, it is proved that the Os-embedded WSe2can be used as a gas sensor for H2S and NH3gas molecules at a high temperature.

Proteobacteria primarily utilize acyl-homoserine lactones (AHLs) as quorum-sensing signals for intra-/interspecies communication to control pathogen infections. Enzymatic degradation of AHL represents the major quorum-quenching mechanism that has been developed as a promising approach to prevent bacterial infections. Here we identified a novel quorum-quenching mechanism revealed by an effector of the type IVA secretion system (T4ASS) in bacterial interspecies competition. We found that the soil antifungal bacterium Lysobacter enzymogenesOH11 (OH11) could use T4ASS to deliver the effector protein Le1288 into the cytoplasm of another soil microbiome bacterium Pseudomonas fluorescens2P24 (2P24). Le1288 did not degrade AHL, whereas its delivery to strain 2P24 significantly impaired AHL production through binding to the AHL synthase PcoI. Therefore, we defined Le1288 as LqqE1 (Lysobacterquorum-quenching effector 1). Formation of the LqqE1-PcoI complex enabled LqqE1 to block the ability of PcoI to recognize/bind S-adenosy-L-methionine, a substrate required for AHL synthesis. This LqqE1-triggered interspecies quorum-quenching in bacteria seemed to be of key ecological significance, as it conferred strain OH11 a better competitive advantage in killing strain 2P24 via cell-to-cell contact. This novel quorum-quenching also appeared to be adopted by other T4ASS-production bacteria. Our findings suggest a novel quorum-quenching that occurred naturally in bacterial interspecies interactions within the soil microbiome by effector translocation. Finally, we presented two case studies showing the application potential of LqqE1 to block AHL signaling in the human pathogen Pseudomonas aeruginosaand the plant pathogen Ralstonia solanacearum.

This paper reports the adsorption of toxic gases (NO2, SO2, and NH3) on a MoSeTe structure based on first principles. It was found that the gas (NO2, SO2, and NH3) adsorption on a pure MoSeTe monolayer was weak; however, the adsorption performance of these gas molecules on transition-metal-atom-supported MoSeTe monolayers (TM–MoSeTe) was better than that on pure MoSeTe monolayers. In addition, there was more charge transfer between gas molecules and TM–MoSeTe. By comparing the adsorption energy and charge transfer values, the trend of adsorption energy and charge transfer in the adsorption of NO2and SO2was determined to be Fe–MoSeTe > Co–MoSeTe > Ni–MoSeTe. For the adsorption of NH3, the effect trend was as follows: Co–MoSeTe > Ni–MoSeTe > Fe–MoSeTe. Finally, by comparing their response times, the better gas sensor was selected. The Ni–MoSeTe system is suitable for NO2gas sensors, and the Fe–MoSeTe and Co–MoSeTe systems are suitable for SO2gas sensors. The Fe–MoSeTe, Co–MoSeTe, and Ni–MoSeTe systems are all suitable for NH3gas sensors. Janus transition-metal dichalcogenides have the potential to be used as gas-sensing and scavenging materials.

Building two-dimensional (2D) vertical van der Waals heterostructures (vdWHs) is one of the effective methods to regulate the properties of single 2D materials. In this paper, we stack the hexagonal boron nitride (h-BN) monolayer (ML) on the SnSe2ML to construct the stable h-BN/SnSe2vdWH, of which the crystal and electronic structures, together with the optical properties, are also analyzed by the first-principles calculations. The results show that the h-BN/SnSe2vdWH belongs to a type-I heterostructure with an indirect bandgap of 1.33 eV, in which the valence band maximum and conduction band minimum are both determined by the component SnSe2ML. Interestingly, the h-BN/SnSe2vdWH under the tensile strain or electric field undergoes the transitions both from type-I to type-II heterostructure and from the indirect to direct bandgap semiconductor. In addition, the carrier mobility of the h-BN/SnSe2heterostructure has a significant enhancement relative to that of the SnSe2ML, up to 104cm2V–1s–1. Meanwhile, the h-BN/SnSe2heterostructure presents the superb optical absorption and unique type-II hyperbolic property. Our findings will broaden the potential applications of SnSe2ML and provide theoretical guidance for the related experimental studies.

Graphic abstract:

[Display omitted] • MoTe 2 is a promising material for NO 2 detection. • The use of metal atom modified substrates greatly transformed the original properties. • The adsorption structures under different systems were explored as gas sensors and scavengers. For the detection of the more hazardous nitrogen oxides (NO 2), there is a need to find a readily fabricated, low-cost, high-performance two-dimensional material. This paper selected three transition metal disulphides (TMDs), MoTe 2 , MoSe 2 and MoS 2 , as materials for detecting NO 2 molecules by density flooding theory (DFT). The results show that the pure Mo(Te/Se/S) 2 monolayer has a poor detection effect on NO 2 molecules, and the modified monolayer exhibits better performance than its natural counterpart due to the significant electron hybridization between the dopant and the gas molecules after the introduction of metal atoms on the surface. It also leads to significant changes in electronic properties and work functions. The charge transfer mechanism based on Hirshfeld analysis shows that the charge transfer from the modified substrate to the NO 2 molecule improves the binding characteristics. And by discussing the adsorption structure, adsorption energy, local electron density, density of states, and frontier orbit theory, we show that MoTe 2 is a promising material for gas detection and removal, which will provide experimentalists with theoretical guidance for the application of Mo(Te/Se/S) 2 based sensing materials. Our work is important for predicting novel monosulfide sensing materials and extending the application of TMDs as chemical gas sensors in the field of environmental monitoring. [ABSTRACT FROM AUTHOR]

The application of intrinsic and transition metals (TM)-doped VSe2monolayers for the detection of faulty gases in SF6electrical insulated equipment is investigated based on first-principles calculations. The electron density difference, density of state, and adsorption energy are analyzed to further clarify the reaction mechanism. The results show that the intrinsic VSe2monolayer has weak adsorption performance for SO2and SOF2molecules, but the adsorption properties of the system are significantly improved after doping TM atoms. Among them, the TM-doped VSe2monolayer has better sensing performance for SO2than for SOF2molecules. Furthermore, the modulating effect of biaxial strain on the gas-sensitive properties of TM-doped VSe2system is also analyzed. Finally, the recovery time of the gas molecules on the solid adsorbent is evaluated. The results confirm that the TM-doped VSe2monolayer can be used as a novel sensing material or scavenger to ensure the normal operation of SF6electrical insulated equipment. This will provide a prospective insight for experimenters to implement VSe2-based sensing materials or scavengers.

Proteobacteria primarily utilize acyl-homoserine lactones (AHLs) as quorum-sensing signals for intra-/interspecies communication to control pathogen infections. Enzymatic degradation of AHL represents the major quorum-quenching mechanism that has been developed as a promising approach to prevent bacterial infections. Here we identified a novel quorum-quenching mechanism revealed by an effector of the type IVA secretion system (T4ASS) in bacterial interspecies competition. We found that the soil antifungal bacterium Lysobacter enzymogenesOH11 (OH11) could use T4ASS to deliver the effector protein Le1288 into the cytoplasm of another soil microbiome bacterium Pseudomonas fluorescens2P24 (2P24). Le1288 did not degrade AHL, whereas its delivery to strain 2P24 significantly impaired AHL production through binding to the AHL synthase PcoI. Therefore, we defined Le1288 as LqqE1 (Lysobacterquorum-quenching effector 1). Formation of the LqqE1-PcoI complex enabled LqqE1 to block the ability of PcoI to recognize/bind S-adenosy-L-methionine, a substrate required for AHL synthesis. This LqqE1-triggered interspecies quorum-quenching in bacteria seemed to be of key ecological significance, as it conferred strain OH11 a better competitive advantage in killing strain 2P24 via cell-to-cell contact. This novel quorum-quenching also appeared to be adopted by other T4ASS-production bacteria. Our findings suggest a novel quorum-quenching that occurred naturally in bacterial interspecies interactions within the soil microbiome by effector translocation. Finally, we presented two case studies showing the application potential of LqqE1 to block AHL signaling in the human pathogen Pseudomonas aeruginosaand the plant pathogen Ralstonia solanacearum.

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Despite their multifaceted advantages, inverted perovskite solar cells (PSCs) still suffer from lower power conversion efficiencies (PCEs) than their regular counterparts, which is largely due to recombination energy losses (Eloss) that arise from the chemical, physical, and energy level mismatches, especially at the interfaces between perovskites and fullerene electron transport layers (ETLs). To address this problem, we herein introduce an aminium iodide derivative of a buckybowl (aminocorannulene) that is molecularly layered at the perovskite–ETL interface. Strikingly, besides passivating the PbI2-rich perovskite surface, the aminocorannulene enforces a vertical dipole and enhances the surface n-type character that is more compatible with the ETL, thus boosting the electron extraction and transport dynamics and suppressing interfacial Eloss. As a result, the champion PSC achieves an excellent PCE of over 22%, which is superior compared to that of the control device (∼20%). Furthermore, the device stability is significantly enhanced, owing to a lock-and-key-like grip on the mobile iodides by the buckybowls and the resultant increase of the interfacial ion-migration barrier. This work highlights the potential of buckybowls for the multifunctional surface engineering of perovskite toward high-performance and stable PSCs.

A highly diastereoselective indium-mediated allylation of 2-N-acetyl glycosyl sulfinylimines in brine under mild reaction conditions is reported. The method allows the achievement of a highly remarkable dichotomous selectivity for substrates, providing a single diastereoisomer of the product in 80–98% yield. With chiral (S)-homoallylic sulfinamide (RS)-5and (RS)-8formed as key intermediates, two potent anti-influenza agents, zanamivir and zanaphosphor, were synthesized in 50% and 41% overall yields, respectively.

Hundreds of C60derivatives stand out as electrontransporting materials(ETMs), for example, in perovskite solar cells(PSCs), due to their properties on electron extraction or defect passivation. However, it still lacks of guidelines to update C60-based ETMs with excellent photoelectric properties. In this work, crystallographic data of eight C60-based ETMs, including pristine C60and the well-known PCBM as well as six newly synthesized fullerenes, are analyzed to establish the connections between derivatized structures and photoelectric properties for the typical carbon cluster of C60. In terms of packing centroid-centroid distance between neighboring carbon cages, the crystallographic data are useful for probing photoelectric properties, such as electrochemical properties, electron mobility and photovoltaic performances, and therefore facilitate to design novel C60-based ETMs for PSCs with high performances.

Speech emotion recognition (SER) is the use of speech signals to estimate the state of emotion. At present, machine learning is one of the main research methods of SER, the test and training dataS of traditional machine learning all have the same distribution and feature space, but the data of speech is accessed from different environments and devices, with different distribution characteristics in real life. Thus, the traditional machine learning method is applied to the poor performance of SER. This paper proposes a multi‐distributed SER method based on Mel frequency cepstogram (MFCC) and parameter transfer. The method is based on single‐layer long short‐term memory (LSTM), pre‐trained inception‐v3 network and multi‐distribution corpus. The speech pre‐processed MFCC is taken as the input of single‐layer LSTM, and input to the pre‐trained inception‐v3 network. The features are extracted through the pre‐trained inception‐v3 model. Then the features are sent to the newly defined the fully connected layer and classification layer, let the parameters of the fully connected layer be fine‐tuned, finally get the classification result. The experiment proves that the method can effectively complete the classification of multi‐distribution speech emotions and is more effective than the traditional machine learning framework of SER.

Ionic liquids (ILs), a new type of absorbents, are widely used to absorb sulfur dioxide (SO2) in flue gas. However, the lack of data on the physical properties of ILs has severely hampered their industrial applications. Unlike previous reports on the specific heat capacity of pure ILs, this work not only focuses on measuring the specific heat capacity of pure ILs but also provides the specific heat capacity of IL and SO2mixtures during the absorption process. First, we measured the specific heat capacities of six ILs including functional ILs, 1,1,3,3-tetramethylguanidinium lactate ([TMG][Lac]), [TMG][suberate], [TMG][dodecanedioate], and 1-butyl-3-methylimidazolium acetate ([Bmim][Ac]), and non-functional ILs, [TMG][tetrafluoroborate] and [Bmim][tetrafluoroborate], at 303.15–333.15 K. We found that the specific heat capacities of the ILs with or without absorbed SO2increase with temperature. The specific heat capacity of ILs increases with the increase of the amount of absorbed SO2. Then, we investigated the effect of the length of anionic alkyl side chains on the specific heat capacity of SO2absorption and found that the specific heat capacity of ILs with shorter alkyl side chains was smaller than that of ILs with longer alkyl side chains. We simulated the absorption process using Gaussian software and found that the specific heat capacities of ILs and SO2systems were mainly caused by the vibration of molecules.

The liquid-phase epoxidation of propylene with H2O2over titanium silicalite-1 (TS-1) zeolite was investigated in detail with a focus on the formation and inhibition of various trace impurities like acetaldehyde, propionaldehyde, acetone, hydroxyacetone, acetals, esters, etc. The results showed that the formation of trace impurities involved the transformation of propylene oxide (PO), its oxidation/isomerization/ring-opening (solvolysis and hydrolysis) byproducts, methanol solvent, and even propylene. Roughly speaking, the epoxidation conditions, viz., low temperature, short residence time, and slightly alkaline reaction medium, that are beneficial to suppress the ring-opening byproducts of PO, were seen facilitating the inhibition of trace impurities as well. To lower the trace impurities via modification of the TS-1 catalyst, the hydrothermal modification of TS-1 with organic amines such as amino-2-propanol (MIPA) was attempted and its effectiveness was demonstrated. The TS-1 zeolite suitably modified by MIPA exhibited abundant Ti–OH groups (3672 cm–1) together with remarkably decreased PO adsorption.

Maillard reactions have been reported extensively. However, full color development kinetics of Maillard reactions have rarely been studied in detail. This study systematically investigated the color development kinetics of Maillard reactions. Thus, arginine (Arg), histidine (His), and lysine (Lys) were each reacted with dihydroxyacetone (DHA) using a simplified model system at different molar ratios, reaction times, pH, and temperatures. Importantly, the browning intensity (at 450 nm) and full color characteristics (within CIE L*a*b* color space) were measured and analyzed in detail. Minitab statistical software was employed to design the factorial experiments and analyze the main and interaction effects. It was found, for the first time, that His and Lys reacted with DHA more rapidly than Arg, and the difference was obvious with the increase of molar ratio and reaction time, reflected in the change of b*. pH 6.2 and higher temperature favored the formation of deeper colored products in amino acid–DHA, accompanied by reduced lightness (L*), significant loss in yellow hues (+b*), and shift toward red hues (+a*). The greatest browning intensities of Arg–DHA (A450= 0.63), His–DHA (A450= 1.12), and Lys–DHA (A450= 1.18) were achieved at molar ratio = 3, 72 h, pH 6.2, and 50 °C, with corresponding L*, a*, and b* values being 54.51, 14.03, 42.75; 48.26, 47.28, 13.59; and 43.35, 53.64, 10.82, respectively.

Breast cancer, the most common cancer in women, is receiving increasing attention. The lack of high-quality medical resources, especially highly skilled doctors, in remote areas makes the diagnosis of breast cancer inefficient and causes great harm to women. The emergence of remote e-health has improved the situation to a certain extent, but its capabilities are still hampered by technical limitations, which manifest in two main aspects. First, due to network bandwidth limitations, it is difficult to guarantee the real-time transmission of breast cancer pathology images between remote areas and cities. Second, the highly skilled breast cancer doctors at large city hospitals are not guaranteed to be available for online diagnosis at all times. To overcome these limitations, this article proposes a deep-learning-empowered breast cancer auxiliary diagnosis scheme for remote e-health supported by 5G technology and beyond (5GB remote e-health). In this scheme, breast pathology images are first received from major hospitals via 5G, and a deep learning model based on the Inception-v3 network is subjected to transfer learning to obtain a diagnostic model. This diagnostic model is then employed on edge servers for auxiliary diagnosis at remote area hospitals. A theoretical analysis and experimental results show that this solution not only overcomes the two problems mentioned above but also improves the diagnostic accuracy for breast cancer in remote areas to 98.19 percent.

Protein-truncating variants (PTVs) have important impacts on phenotype diversity and disease. However, their population genetics characteristics in more globally diverse populations are not well defined. Here, we describe patterns of PTVs in 1320 genes sequenced in 10,539 healthy controls and 9434 patients with psoriasis, all of Han Chinese ancestry. We identify 8720 PTVs, of which 77% are novel, and estimate 88% of all PTVs are deleterious and subject to purifying selection. Furthermore, we show that individuals with psoriasis have a significantly higher burden of PTVs compared to controls (P= 0.02). Finally, we identified 18 PTVs in 14 genes with unusually high levels of population differentiation, consistent with the action of local adaptation. Our study provides insights into patterns and consequences of PTVs.

A transition-metal- and oxidant-free electrochemical strategy for radical fluoroalkylation of vinyl azides was developed. The reaction was carried out under mild conditions by using inexpensive and bench-stable RfSO2Na (Rf= CF3, CF2H) as fluorination reagents. Depending on the starting material, both the electrochemical radical cyclization and dearomatization products could be obtained. This method provides a green and safe approach to synthesize fluorinated nitrogen heterocycles.

A defective HZSM-5 zeolite (SiO2/Al2O3= 55, crystal size = 300 nm) with a high density of hydroxyl nests and its patched-up counterpart obtained by pretreating the defective zeolite with (NH4)2SiF6were employed to investigate the effect of zeolitic hydroxyl nests on the acidity and propane aromatization performance of zinc nitrate-impregnated HZSM-5 zeolite. Catalyst characterizations show that, in the case of impregnating the defective HZSM-5 zeolite, zinc ions were preferentially introduced into the zeolitic hydroxyl nests, forming subnanomeric ZnO clusters as Lewis acid sites (showed 1451 cm–1infrared (IR) adsorption feature when adsorbed by pyridine). By contrast, when the hydroxyl nests of the defective zeolite were patched by (NH4)2SiF6pretreatment, the zinc ions were mainly ushered in as isolated Zn2+and bulky ZnO particles, the former species were the known Lewis acid sites (showed 1455 cm–1IR adsorption feature when adsorbed by pyridine) located at the counter-cation positions of zeolitic bridging hydroxyls. Propane aromatization operando infrared spectroscopic study and pulse microreactor evaluation indicated that the zeolitic hydroxyl nests-stabilized subnanomeric ZnO clusters had clear advantage over the known isolated Zn2+Lewis acid sites in the dehydroaromatization of propane.

In p-i-nstructure perovskite solar cells (PSCs), the most prevalent electron transport layer (ETL), [6, 6]-phenyl-C61-butyric acid methyl ester (PC61BM), acts as both electron extractor and protective coverage to the underlayer perovskite. Notably, multifunctional mixed fullerene ETLs show great potential in further improving both the power conversion efficiency (PCE) and stability of PSCs compared to the single PC61BM ETL. In this work, we reported the mixed fullerene ETLs comprising of PC61BM and its two analogs with different length of fluorocarbon chains, [6, 6]-phenyl-C61-buryric acid 1H,1H-trifluoro-1-ethyl ester (abbreviated, CF3–PC61BM) and [6, 6]-phenyl-C61-buryric acid 1H, 1H-tridecafluoro-1-heptyl ester (abbreviated, C6F13–PC61BM). We obtained excellent PCEs of 18.37% and 17.71% for 1 wt % CF3–PC61BM- and C6F13–PC61BM-based PSCs (1 wt % addition of PC61BM) with CH3NH3PbI3(MAPbI3) perovskites, respectively. Moreover, champion PCEs of ∼19% were obtained based on the CsFAMAPbIBr perovskites. Subsequent experiments demonstrated that the fluorocarbon chains of CF3–PC61BM and C6F13–PC61BM assembled at the surfaces of ETLs with the formation of thin-layer moisture-resistant protective coverage above perovskite. Results show that it significantly retarded water penetrating down to perovskite layers and led to optimal humidity stability under ambient atmosphere.

Metallic nanoclusters (NCs) have molecular-like structures and unique physical and chemical properties, making them an interesting new class of luminescent nanomaterials with various applications in chemical sensing, bioimaging, optoelectronics, light-emitting diodes (LEDs), etc. However, weak photoluminescence (PL) limits the practical applications of NCs. Herein, an effective and facile strategy of enhancing the PL of NCs was developed using Ag shell-isolated nanoparticle (Ag SHIN)-enhanced luminescence platforms with tuned SHINs shell thicknesses. 3D-FDTD theoretical calculations along with femtosecond transient absorption and fluorescence decay measurements were performed to elucidate the enhancement mechanisms. Maximum enhancements of up to 231-fold for the [Au7Ag8(C≡CtBu)12]+cluster and 126-fold for DNA-templated Ag NCs (DNA–Ag NCs) were achieved. We evidenced a novel and versatile method of achieving large PL enhancements with NCs with potential for practical biosensing applications for identifying target DNA in ultrasensitive surface analysis.