Phase-controlled synthesis of SnS2and SnS flakes and photodetection properties

Two-dimensional (2D) layered tin sulfide compounds including SnS₂and SnS have attracted increasing attention due to their great potential application in the fields of optoelectronics and energy storage. However, device development has been delayed by the lack of capabilities to synthesize large-scale and high-quality 2D tin sulfide. Here, a phase-controlled synthesis of SnS₂and SnS flakes with lateral size over 100 μm was successfully realized via a facile chemical vapor deposition method. The lateral size of flakes and phase transformation of SnS₂to SnS can be tuned via changing the synthesis temperature. Compared to the formation of the SnS₂phase at relative low temperature (<750 °C), the SnS phase is favorable at higher temperature. The phototransistor based on the as-prepared SnS₂and SnS exhibits excellent photoresponse to 405 nm laser, including a high responsivity (1.7 × 10⁶mA W^-1), fast response rates (rise/decay time of 13/51 ms), an outstanding external quantum efficiency (5.3 × 10⁵%), and a remarkable detectivity (6.24 × 10¹²Jones) for SnS₂-based phototransistor, and these values are superior to the most reported SnS₂based photodetectors. Although the responsivity (3390 mA W^-1) and detectivity (1.1 × 10¹⁰Jones) of SnS-based device is lower than that of the SnS₂phototransistor, it has a faster rise/decay time of 3.10/1.59 ms. This work provides a means of tuning the size and phase of 2D layered tin sulfide, and promotes the application of SnS₂in high-performance optoelectronic devices.

Application Progress of Deinococcus radiodurans in Biological Treatment of Radioactive Uranium-Containing Wastewater

Radioactive uranium wastewater contains a large amount of radionuclide uranium and other heavy metal ions. The radioactive uranium wastewater discharged into the environment will not only pollute the natural environment, but also threat human health. Therefore, the treatment of radioactive uranium wastewater is a current research focus for many researchers. The treatment in radioactive uranium wastewater mainly includes physical, chemical and biological methods. At present, the using of biological treatment to treat uranium in radioactive uranium wastewater has been gradually shown its superiority and advantages. Deinococcus radiodurans is a famous microorganism with the most radiation resistant to ionizing radiation in the world, and can also resist various other extreme pressures. D. radiodurans can be directly used for the adsorption of uranium in radioactive waste water, and it can also transform other functional genes into D. radiodurans to construct genetically engineered bacteria, and then applied to the treatment of radioactive uranium containing wastewater. Radionuclides uranium in radioactive uranium-containing wastewater treated by D. radiodurans involves a lot of mechanisms. This article reviews currently the application of D. radiodurans that directly or construct genetically engineered bacteria in the treatment of radioactive uranium wastewater and discusses the mechanism of D. radiodurans in bioremediation of uranium. The application of constructing an engineered bacteria of D. radiodurans with powerful functions in uranium-containing wastewater is prospected.

Three-Dimensional Genome Interactions Identify Potential Adipocyte Metabolism-Associated Gene STON1 and Immune-Correlated Gene FSHR at the rs13405728 Locus in Polycystic Ovary Syndrome

Background

rs13405728 was identified as one of the most prevalent susceptibility loci for polycystic ovary syndrome (PCOS) in Han Chinese and Caucasian women. However, the target genes and potential mechanisms of the rs13405728 locus remain to be determined.

Methods

Three-dimensional (3D) genome interactions from the ovary tissue were characterized via high-through chromosome conformation capture (Hi-C) and Capture Hi-C technologies to identify putative targets at the rs13405728 locus. Combined analyses of eQTL, RNA-Seq, DNase-Seq, ChIP-Seq, and sing-cell sequencing were performed to explore the molecular roles of these target genes in PCOS. PCOS-like mice were applied to verify the expression patterns.

Results

Generally, STON1 and FSHR were identified as potential targets of the rs13405728 locus in 3D genomic interactions with epigenomic regulatory peaks, with STON1 (P=0.0423) and FSHR (P=0.0013) being highly expressed in PCOS patients. STON1 co-expressed genes were associated with metabolic processes (P=0.0008) in adipocytes (P=0.0001), which was validated in the fat tissue (P<0.0001) and ovary (P=0.0035) from fat-diet mice. The immune system process (GO:0002376) was enriched in FSHR co-expressed genes (P=0.0002) and PCOS patients (P=0.0002), with CD4 high expression in PCOS patients (P=0.0316) and PCOS-like models (P=0.0079). Meanwhile, FSHR expression was positively correlated with CD4 expression in PCOS patients (P=0.0252) and PCOS-like models (P=0.0178). Furthermore, androgen receptor (AR) was identified as the common transcription factor for STON1 and FSHR and positively correlated with the expression of STON1 (P=0.039) and FSHR (P=4e-06) in ovary tissues and PCOS-like mice.

Conclusion

Overall, we identified STON1 and FSHR as potential targets for the rs13405728 locus and their roles in the processes of adipocyte metabolism and CD4 immune expression in PCOS, which provides 3D genomic insight into the pathogenesis of PCOS.

Role of the Receptor for Advanced Glycation End Products in Heat Stress-Induced Endothelial Hyperpermeability in Acute Lung Injury

Objective

To study the role of the receptor for advanced glycation end products (RAGE) in endothelial barrier dysfunction induced by heat stress, to further explore the signal pathway by which RAGE contributes to heat-induced endothelia response, and thereby find a novel target for the clinical treatment of ALI (acute lung injury) induced by heatstroke.

Methods

This study established the animal model of heatstroke using RAGE knockout mice. We observed the role of RAGE in acute lung injury induced by heatstroke in mice by evaluating the leukocytes, neutrophils, and protein concentration in BALF (Bronchoalveolar lavage fluids), lung wet/dry ratio, histopathological changes, and the morphological ultrastructure of lung tissue and arterial blood gas analysis. To further study the mechanism, we established a heat stress model of HUVEC and concentrated on the role of RAGE and its signal pathway in the endothelial barrier dysfunction induced by heat stress, measuring Transendothelial electrical resistance (TEER) and western blot.

Results

RAGE played a key role in acute lung injury induced by heatstroke in mice. The mechanism C-Jun is located in the promoter region of the RAGE gene. C-Jun increased the RAGE protein expression while HSF1 suppressed RAGE protein expression. The overexpressed RAGE protein then increased HUVEC monolayer permeability by activating ERK and P38 MAPK under heat stress.

Conclusion

This study indicates the critical role of RAGE in heat stress-induced endothelial hyperpermeability in acute lung injury and suggests that RAGE could be a potential therapeutic target in protecting patients against acute lung injury induced by heatstroke.

Molecular Profiling Reveals Common and Specific Development Processes in Different Types of Gynecologic Cancers

BACKGROUND

Gynecologic cancers have become a major threat to women's health. The molecular biology of gynecologic cancers is not as well understood as that of breast cancer, and precision targeting is still new. Although viewed collectively as a group of cancers within the female reproductive system, they are more often studied separately. A comprehensive within-group comparison on molecular profiles is lacking.

METHODS

We conducted a whole-exome sequencing study of cervical/endometrial/ovarian cancer samples from 209 Chinese patients. We combined our data with genomic and transcriptomic data from relevant TCGA cohorts to identify and verify common/exclusive molecular changes in cervical/endometrial/ovarian cancer.

RESULTS

We identified shared molecular features including a COSMIC signature of deficient mismatch repair (dMMR), four recurrent copy-number variation (CNV) events, and extensive alterations in PI3K-Akt-mTOR signaling and cilium component genes; we also identified transcription factors and pathways that are exclusively altered in cervical/endometrial/ovarian cancer. The functions of the commonly/exclusively altered genomic circuits suggest (1) a common reprogramming process during early tumor initiation, which involves PI3K activation, defects in mismatch repair and cilium organization, as well as disruption in interferon signaling and immune recognition; (2) a cell-type specific program at late-stage tumor development that eventually lead to tumor proliferation and migration.

CONCLUSION

This study describes, from a molecular point of view, how similar and how different gynecologic cancers are, and it provides a hypothesis about the causes of the observed similarities and differences.

Efficacy of intrauterine perfusion of peripheral blood mononuclear cells (PBMC) for infertile women before embryo transfer: meta-analysis

This meta-analysis was intended to evaluate the effects of intrauterine perfusion of peripheral blood mononuclear cells (PBMC) on the pregnancy outcomes including clinical pregnancy rates, embryo implantation rates, live birth rates and miscarriage rates of infertile women who were undergoing in vitro fertilisation (IVF) treatment. By searching Pubmed, Embase database, five articles meeting the inclusion criteria were included, and 1173 women were enrolled (intrauterine PBMC group: n = 514; NO-PBMC group: n = 659). For the entire IVF/ICSI population and one or two embryo transfer failure patients, there was no significant difference in endometrial thickness, embryo implantation rates, live birth rates, and miscarriage rates between the PBMC group and NO-PBMC group. Although the clinical pregnancy rates of the PBMC group were higher than that of the NO-PBMC group, the confidence interval was close to the line of unity. As for the patients with three or more implantation failures, the clinical pregnancy rates, embryo implantation rates and live birth rates were much higher in the PBMC group than that of the NO-PBMC group. In summary, current evidence suggests that intrauterine perfusion of PBMC can significantly improve pregnancy outcomes in patients who have three or more implantation failures.Impact statementWhat is already known on this subject? An increasing number of studies have shown that immune cells play an important role in embryo transfer. There is no reliable evidence to confirm the clinical efficacy of intrauterine perfusion of PBMC.What do the results of this study add? The current evidence suggests that intrauterine perfusion of PBMC can significantly improve pregnancy outcomes in patients who have three or more implantation failures.What are the implications of these findings for clinical practice and/or further research? To the best of our knowledge, this meta-analysis is the first to evaluate the effect of intrauterine perfusion of PBMC on pregnancy outcomes before embryo transfer. Our study indicated that intrauterine perfusion of PBMC significantly increased clinical pregnancy rates, embryo implantation rates, and live birth rates in patients who failed more than three implants.

A molecular insight into the dissociable regulation of associative learning and motivation by the synaptic protein neuroligin-1

Background

In a changing environment, a challenge for the brain is to flexibly guide adaptive behavior towards survival. Complex behavior and the underlying neural computations emerge from the structural components of the brain across many levels: circuits, cells, and ultimately the signaling complex of proteins at synapses. In line with this logic, dynamic modification of synaptic strength or synaptic plasticity is widely considered the cellular level implementation for adaptive behavior such as learning and memory. Predominantly expressed at excitatory synapses, the postsynaptic cell-adhesion molecule neuroligin-1 (Nlgn1) forms trans-synaptic complexes with presynaptic neurexins. Extensive evidence supports that Nlgn1 is essential for NMDA receptor transmission and long-term potentiation (LTP), both of which are putative synaptic mechanisms underlying learning and memory. Here, employing a comprehensive battery of touchscreen-based cognitive assays, we asked whether impaired NMDA receptor transmission and LTP in mice lacking Nlgn1 does in fact disrupt decision-making. To this end, we addressed two key decision problems: (i) the ability to learn and exploit the associative structure of the environment and (ii) balancing the trade-off between potential rewards and costs, or positive and negative utilities of available actions.

Results

We found that the capacity to acquire complex associative structures and adjust learned associations was intact. However, loss of Nlgn1 alters motivation leading to a reduced willingness to overcome effort cost for reward and an increased willingness to exert effort to escape an aversive situation. We suggest Nlgn1 may be important for balancing the weighting on positive and negative utilities in reward-cost trade-off.

Conclusions

Our findings update canonical views of this key synaptic molecule in behavior and suggest Nlgn1 may be essential for regulating distinct cognitive processes underlying action selection. Our data demonstrate that learning and motivational computations can be dissociated within the same animal model, from a detailed behavioral dissection. Further, these results highlight the complexities in mapping synaptic mechanisms to their behavioral consequences, and the future challenge to elucidate how complex behavior emerges through different levels of neural hardware.

Assessing concordance among human, in silico predictions and functional assays on genetic variant classification

MOTIVATION

A variety of in silico tools have been developed and frequently used to aid high-throughput rapid variant classification, but their performances vary, and their ability to classify variants of uncertain significance were not systemically assessed previously due to lack of validation data. This has been changed recently by advances of functional assays, where functional impact of genetic changes can be measured in single-nucleotide resolution using saturation genome editing (SGE) assay.

RESULTS

We demonstrated the neural network model AIVAR (Artificial Intelligent VARiant classifier) was highly comparable to human experts on multiple verified datasets. Although highly accurate on known variants, AIVAR together with CADD and PhyloP showed non-significant concordance with SGE function scores. Moreover, our results indicated that neural network model trained from functional assay data may not produce accurate prediction on known variants.

AVAILABILITY AND IMPLEMENTATION

All source code of AIVAR is deposited and freely available at https://github.com/TopGene/AIvar.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Early-stage corrosion, ion release, and the antibacterial effect of copper and cuprous oxide in physiological buffers: Phosphate-buffered saline vs Na-4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid

Copper surfaces are well known for their antibacterial effects due to the release of copper ions. This benefit has been shown in many antibacterial efficiency tests, however, without considering the corrosion behaviors of copper in the physiological solutions, which could play an indispensable role in ion release from the metallic surface. This study compared the ground copper surface and sputtered cuprous oxide (Cu₂O) coating in two common physiological buffers: phosphate-buffered saline (PBS) and Na-4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (Na-HEPES). The growth of the cuprous oxide (Cu₂O) layer was found on copper in pure PBS, inhibiting further copper ion release. In contrast, a continuous release of copper ions was recorded in Na-HEPES for 3 h, where no oxide formation was observed. The antibacterial efficiency of copper (against E. coli) was measured and discussed with the ion release kinetics in the presence of E. coli. Similar results were obtained from Cu₂O coating, ruling out its assisting role in showing the antibacterial property from copper surfaces, but they did indicate the importance of taking environmental parameters into consideration in interpreting the antibacterial efficiency of copper surfaces.

The effect of salpingectomy on the ovarian reserve and ovarian response in ectopic pregnancy: A systematic review and meta-analysis

BACKGROUND

Salpingectomy is routinely performed in ectopic pregnancy (EP). However, the effect of the surgery on the ovarian reserve and ovarian response in EP patients is still uncertain and has not been systematically evaluated. Therefore, we conducted this meta-analysis to provide a comparison of the ovarian reserve and ovarian response between the pre-salpingectomy and post-salpingectomy in EP patients.

METHODS

Pubmed, Embase, and Cochrane Library were searched for all relevant articles published up to December 2018. We retrieved the basic information and data of the included studies. The data was analyzed by Review Manager 5.3 software (Cochrane Collaboration, Oxford, UK).

RESULTS

A total of 243 articles were extracted from the databases, and 7 studies were included in the meta-analysis. The ovarian reserve including anti-Mullerian hormone (inverse variance [IV] -0.7 [95% confidence interval [CI] -0.63, 0.49]), antral follicle count (IV 1.7 [95% CI -2.02, 5.42]) and basal follicle stimulating hormone (IV 0.02 [95% CI -0.63, 0.68]) was comparable between the pre-salpingectomy group and the post-salpingectomy group. The amount of gonadotropin was significantly higher in the post-salpingectomy group when compared with that in the pre-salpingectomy group (IV -212.65 [95% CI -383.59, -41.71]). There was no significant difference in the left parameters of the ovarian response including the duration of gonadotropin stimulation (IV -0.32 [95% CI -0.76, 0.12]), the estrogen level on the human chorionic gonadotropin triggering day (IV -4.12 [95% CI -236.27, -228.04]) and the number of retrieved oocytes (IV 0.35 [95% CI -0.76, 1.46]) between 2 groups.

CONCLUSIONS

The current results suggest that salpingectomy has no negative effect on the ovarian reserve and ovarian response.

Bacteria accumulate copper ions and inhibit oxide formation on copper surface during antibacterial efficiency test

Copper surface after antibacterial test against E. coli was examined in the aspect of corrosion. Results from scanning electron microscope (SEM), grazing incidence X-ray diffractometer (GIXRD) and Raman spectroscopy together confirmed less oxidation on copper surface with the presence of E. coli. The inhibition of the cuprous oxide (Cu₂O) layer instead ensured the continuous exposure of copper surface, letting localised corrosion attacks observable and causing a stronger release of copper ions. These phenomena are attributed to the fact that E. coli act as ions reservoirs since high amount of copper accumulation were found by energy dispersive X-ray spectroscopy (EDS).

[Detection and analysis of FAM19A4 promoter methylation in cervical exfoliated cells]

Objective: To investigate the cinical value of FAM19A4promoter methylation in cervicalexfoliated cells for triage of cervical cancer. Methods: A total of 162 high-risk HPV-infected patients who were pathologically confirmed as different cervical lesions from August 2017 to December 2017 were collected in Guangdong Women and Children Hospital. Taqman probe-based quantitative PCR (qPCR) was used to detect the methylation of FAM19A4 promoterin different grades of cervical lesions, and the value of FAM19A4 methylation in predicting cervical HSIL and the above lesions was calculated by diagnostic test. Results: (1)The positive rates of FAM19A4 methylation in cervical exfoliated cells increased with the severity of cervical lesions, which were 7.69% (4/52) , 34.62% (9/26) , 55.56% (20/36) , 95.83% (46/48) in normal cervix/cervicitis, cervical LSIL, HSIL, and cervical cancer, respectively(P<0.05).(2)There was no significant difference in the detection rates of FAM19A4 methylation between different age groups, pathological types, clinical stage, tumor size and lymph node metastasis status (P>0.05). (3) The specificity and positive predictive value of FAM19A4 methylation in detecting cervical HSIL alone and ≥HSIL lesions were the optimal, with the AUC of 0.69 and 0.84, respectively. When combined with HPV16/18 genotyping, the sensitivity was significantly improved. Conclusions: The detection of FAM19A4 promoter methylation in cervical exfoliated cells has a high clinical value of discriminating ≥HSIL lesions; and the cotest of methylated FAM19A4 and HPV16/18 genotyping can identify ≥HSIL lesions more sensitively.

Construction and preliminary identification of a prokaryotic expression single-chain antibody fragments library against Streptococcus pneumoniae from antibody-producing cells in human tonsil

Tonsillitis is the inflammation of the tonsils due to infection, many patients ultimately have to undergo tonsillectomy. In order to improve the accuracy of diagnosis and even create a new treatment for tonsillitis, we constructed a prokaryotic expression single-chain antibody fragment library against Streptococcus pneumoniae with immunoglobulin heavy chain variable region (VH), κ light chain (Vκ), and λ light chain (Vλ) genes by using human tonsil tissue. Plasmid DNA sequencing showed that single-chain antibodies were complete and constructed correctly. The binding activity of recombinant clones was detected by enzyme-linked immunosorbent assay (ELISA), results showed that the binding activity and specificity of anti-S. pneumoniae single-chain fragment variable (scfv) is proved to be successful. The single-chain antibody may be an attractive strategy for tonsillitis etiologic diagnosis and therapy.

Germline TP53 and MSH6 mutations implicated in sporadic triple-negative breast cancer (TNBC): a preliminary study

Background

Germline BRCA1/2 prevalence is relatively low in sporadic triple-negative breast cancer (TNBC). We hypothesized that non-BRCA genes may also have significant germline contribution to Chinese sporadic TNBC, and the somatic mutational landscape of TNBC may vary between ethnic groups. We therefore conducted this study to investigate germline and somatic mutations in 43 cancer susceptibility genes in Chinese sporadic TNBC.

Patients and methods

Sixty-six Chinese sporadic TNBC patients were enrolled in this study. Germline and tumor DNA of each patient were subjected to capture-based next-generation sequencing using a 43-gene panel. Standard bioinformatic analysis and variant classification were performed to identify deleterious/likely deleterious germline mutations and somatic mutations. Mutational analysis was conducted to identify significantly mutated genes.

Results

Deleterious/likely deleterious germline mutations were identified in 27 (27/66, 40.9%) patients. Among the 27 patients, 9 (9/66, 13.6%) were TP53 carriers, 5 (5/66, 7.6%) were MSH6 carriers, and 5 (5/66, 7.6%) were BRCA1 carriers. Somatic mutations were identified in 64 (64/66, 97.0%) patients. TP53 somatic mutations occurred in most of the patients (45/66, 68.2%) and with highest mean allele frequency (28.1%), while NF1 and POLE were detected to have the highest mutation counts.

Conclusions

Our results supported our hypotheses and suggested great potentials of TP53 and MSH6 as novel candidates for TNBC predisposition genes. The high frequency of somatic NF1 and POLE mutations in this study showed possibilities for clinical benefits from androgen-blockade therapies and immunotherapies in Chinese TNBC patients. Our study indicated necessity of multi-gene testing for TNBC prevention and treatment.

Electronic supplementary material

The online version of this article (10.1186/s40246-018-0186-y) contains supplementary material, which is available to authorized users.

Adsorption of Cu2+ and mechanism by natural biofilm

The biofilm culturing device fixed on the slides was vertically placed in the commonly called small Li Lake of Jiangnan University. The adsorption experiment of Cu²⁺ was carried out by mature biofilm. Besides, scanning electron microscope (SEM), polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy-energy spectrum (SEM-EDX) were used to analysis the effect of Cu²⁺ on the morphological structure of biofilm. The result indicated that when the initial concentration of Cu²⁺ was 5 mg·L^-1, the absorption capacity of Cu²⁺ by unit mass biofilm is the maximum. More extracellular polymeric substances (EPS) were released by biofilm due to the stimulation of Cu²⁺. EPS was beneficial to the adsorption of Cu²⁺ by biofilm. After the adsorption of Cu²⁺, the bacterial diversity index decreased, while there were no significant differences in microbial communities on biofilm. Moreover, the main groups combining Cu²⁺ were the hydroxyl groups and amide groups in S-EPS and B-EPS. Ion exchange is a mechanism of the adsorption of Cu²⁺ by EPS.

Design of a spaceflight biofilm experiment

Biofilm growth has been observed in Soviet/Russian (Salyuts and Mir), American (Skylab), and International (ISS) Space Stations, sometimes jeopardizing key equipment like spacesuits, water recycling units, radiators, and navigation windows. Biofilm formation also increases the risk of human illnesses and therefore needs to be well understood to enable safe, long-duration, human space missions. Here, the design of a NASA-supported biofilm in space project is reported. This new project aims to characterize biofilm inside the International Space Station in a controlled fashion, assessing changes in mass, thickness, and morphology. The space-based experiment also aims at elucidating the biomechanical and transcriptomic mechanisms involved in the formation of a "column-and-canopy" biofilm architecture that has previously been observed in space. To search for potential solutions, different materials and surface topologies will be used as the substrata for microbial growth. The adhesion of bacteria to surfaces and therefore the initial biofilm formation is strongly governed by topographical surface features of about the bacterial scale. Thus, using Direct Laser-Interference Patterning, some material coupons will have surface patterns with periodicities equal, above or below the size of bacteria. Additionally, a novel lubricant-impregnated surface will be assessed for potential Earth and spaceflight anti-biofilm applications. This paper describes the current experiment design including microbial strains and substrata materials and nanotopographies being considered, constraints and limitations that arise from performing experiments in space, and the next steps needed to mature the design to be spaceflight-ready.

Flexible single-mode delivery of a high-power 2 μm pulsed laser using an antiresonant hollow-core fiber

We demonstrate flexible single-mode transmission of a high average power 2 µm nanosecond pulse using antiresonant hollow-core fibers (AR-HCFs). 39.1 W average power is delivered using a coiled 1.7 m AR-HCF, which is designed for single-mode guidance and good higher-order mode suppression. The effect of bending on the fiber output power and beam profile is also investigated. The Gaussian-like output beam profile is maintained up to a 7.5 cm bending radius. This is the highest average power delivered by a flexible long HCF in this wavelength without the need for an enclosed controlled environment, to the best of our knowledge.

High-efficiency ultrafast Tm-doped fiber amplifier based on resonant pumping

We demonstrated a high-efficiency ultrafast Tm-doped fiber amplifier based on a resonant pumping technique. A continuous-wave fiber laser at 1940 nm was employed as the pump laser. The slope efficiency of the resonantly pumped pulsed Tm-doped fiber amplifier reached 87% with respect to the launched pump power. The maximum average output power reached 40 W when the launched pump power was 53 W. The repetition rate and the pulse duration of the output pulses from a fiber amplifier were 248 MHz and 129 ps, respectively. The corresponding peak power was 1.25 kW, and the pulse energy was 161.3 nJ. To the best of our knowledge, this is the first demonstration of a resonant pumping enabled high-power high-efficiency ultrafast fiber laser operating at a 2 μm band.