Exposure to endocrine disruptor DEHP promotes the progression and radiotherapy resistance of pancreatic cancer cells by increasing BMI1 expression and properties of cancer stem cells.

Most patients diagnosed with pancreatic cancer are initially at an advanced stage, and radiotherapy resistance impact the effectiveness of treatment. This study aims to investigate the effects of endocrine disruptor Di-(2-ethylhexyl) phthalate (DEHP) on various biological behaviors and the radiotherapy sensitivity of pancreatic cancer cells, as well as its potential mechanisms. Our findings indicate that exposure to DEHP promotes the proliferation of various cancer cells, including those from the lung, breast, pancreas, and liver, in a time- and concentration-dependent manner. Furthermore, DEHP exposure could influence several biological behaviors of pancreatic cancer cells in vivo and vitro. These effects include reducing cell apoptosis, causing G0/G1 phase arrest, increasing migration capacity, enhancing tumorigenicity, elevating the proportion of cancer stem cells (CSCs), and upregulating expression levels of CSCs markers such as CD133 and BMI1. DEHP exposure can also increase radiation resistance, which can be reversed by downregulating BMI1 expression. In summary our research suggests that DEHP exposure can lead to pancreatic cancer progression and radiotherapy resistance, and the mechanism may be related to the upregulation of BMI1 expression, which leads to the increase of CSCs properties.

5 nm Nanogap Electrodes and Arrays by Super-resolution Laser Lithography.

The development of reliable, mass-produced, and cost-effective sub-10 nm nanofabrication technology leads to an unprecedented level of integration of photonic devices. In this work, we describe the development of a laser direct writing (LDW) lithography technique with ∼5 nm feature size, which is about 1/55 of the optical diffraction limit of the LDW system (405 nm laser and 0.9 NA objective), and the realization of 5 nm nanogap electrodes. This LDW lithography exhibits an attractive capability of well-site control and mass production of ∼5 × 105 nanogap electrodes per hour, breaking the trade-off between resolution and throughput in a nanofabrication technique. Nanosensing chips have been demonstrated with the as-obtained nanogap electrodes, where controllable surface enhancement Raman scattering of rhodamine 6G has been realized via adjusting the gap width and, especially, the applied bias voltages. Our results establish that such a low-cost and high-efficient lithography technology has great potential to fabricate compact integrated circuits and biochips.

Hybrid Fiber Optic Sensor, Based on the Fabry⁻Perot Interference, Assisted with Fluorescent Material for the Simultaneous Measurement of Temperature and Pressure.

Herein we design a fiber sensor able to simultaneously measure the temperature and the pressure under harsh conditions, such as strong electromagnetic interference and high pressure. It is built on the basis of the fiber-optic Fabry⁻Perot (F⁻P) interference and the temperature sensitive mechanism of fluorescent materials. Both halogen lamps and light-emitting diodes (LED) are employed as the excitation light source. The reflected light from the sensor contains the low coherent information of interference cavity and the fluorescent lifetime. This information is independent due to the separate optical path and the different demodulation device. It delivers the messages of pressure and temperature, respectively. It is demonstrated that the sensor achieved pressure measurement at the range of 120⁻400 KPa at room temperature with a sensitivity of 1.5 nm/KPa. Moreover, the linearity of pressure against the cavity length variation was over 99.9%. In the meantime, a temperature measurement in the range of 25⁻80 °C, with a sensitivity of 0.0048 ms/°C, was obtained. These experimental results evince that this kind of sensor has a simple configuration, low-cost, and easy fabrication. As such, it can be particularly applied to many fields.

Comparative transcriptome analysis of male and female gonads reveals sex-biased genes in spotted scat (Scatophagus argus).

Scatophagus argus is a new emerging aquaculture fish in East and Southeast Asia. To date, research on reproductive development and regulation in S. argus is lacking. Additionally, genetic and genomic information about reproduction, such as gonadal transcriptome data, is also lacking. Herein, we report the first gonadal transcriptomes of S. argus and identify genes potentially involved in reproduction and gonadal development. A total of 136,561 unigenes were obtained by sequencing of testes (n = 3) and ovaries (n = 3) at stage III. Genes upregulated in males and females known to be involved in gonadal development and gametogenesis were identified, including male-biased dmrt1, amh, gsdf, wt1a, sox9b, and nanos2, and female-biased foxl2, gdf9, bmp15, sox3, zar1, and figla. Serum estradiol-17ß and 11-ketotestosterone levels were biased in female and male fish, respectively. Sexual dimorphism of serum steroid hormone levels were interpreted after expression analysis of 20 steroidogenesis-related genes, including cyp19a1a and cyp11b2. This gonadal transcript dataset will help investigate functional genes related to reproduction in S. argus.

Room-temperature quantum cascade superluminescent light emitters with wide bandwidth and high temperature stability.

The realization of room-temperature (RT) mid-infrared (MIR) broadband light sources is fundamentally interesting and highly desirable for a number of applications. Recently, superluminescent light emitters (SLEs) based on quantum cascade (QC) structures have emerged as excellent candidates among mid-infrared broadband light sources. However, it is challenging to achieve RT-QCSLEs due to the very low efficiency of the spontaneous emission in the intersubband transitions. Here, we demonstrate the realization of a set of ~5 µm RT-SLEs under continuous wave (CW) or quasi-CW (10% duty circle) operation by using a two-phonon resonant QC active region and monolithic integrated waveguide structures. In addition, with the design of an inclined tapered cavity, the SLEs exhibit high milliwatt power, large spectral width of more than 200 cm-1 and good temperature characteristic. These demonstrated results are believed to be a big step forward to the applications of broadband MIR semiconductor light sources.

Graphene-Ag Hybrids on Laser-Textured Si Surface for SERS Detection.

Surface-enhanced Raman scattering (SERS) has been extensively investigated as an effective approach for trace species detection. Silver nanostructures are high-sensitivity SERS substrates in common use, but their poor chemical stability impedes practical applications. Herein, a stable and sensitive SERS substrate based on the hybrid structures of graphene/silver film/laser-textured Si (G/Ag/LTSi) was developed, and a simple, rapid, and low-cost fabrication approach was explored. Abundant nanoparticles were directly created and deposited on the Si surface via laser ablation. These aggregated nanoparticles functioned as hotspots after a 30 nm Ag film coating. A monolayer graphene was transferred to the Ag film surface to prevent the Ag from oxidation. The SERS behavior was investigated by detecting R6G and 4-MBT molecules. The experimental results indicate that the maximum enhancement factor achieved by the G/Ag/LTSi substrate is over 107 and less than 23% SERS signals lost when the substrate was exposed to ambient conditions for 50 days. The covering graphene layer played crucial roles in both the Raman signals enhancement and the Ag nanostructure protection. The stable and sensitive SERS performance of G/Ag/LTSi substrate evince that the present strategy is a useful and convenient route to fabricate large-area graphene-silver plasmonic hybrids for SERS applications.

[Retracted] Radioprotective effects of pyrroloquinoline quinone on parotid glands in C57BL/6J mice.

[This retracts the article DOI: 10.3892/etm.2016.3843.].

X-Box binding protein 1 downregulates SIRT6 to promote injury in pancreatic ductal epithelial cells.

OBJECTIVE: Acute pancreatitis (AP) stands as a frequent cause for clinical emergency hospital admissions. The X-box binding protein 1 (XBP1) was found to be implicated in pancreatic acinar cell apoptosis. The objective is to unveil the potential mechanisms governed by XBP1 and SIRT6 in the context of AP. METHODS: Caerulein-treated human pancreatic duct epithelial (HPDE) cells to establish an in vitro research model. The levels and regulatory role of SIRT6 in the treated cells were evaluated, including its effects on inflammatory responses, oxidative stress, apoptosis, and endoplasmic reticulum stress. The relationship between XBP1 and SIRT6 was explored by luciferase and ChIP experiments. Furthermore, the effect of XBP1 overexpression on the regulatory function of SIRT6 on cells was evaluated. RESULTS: Caerulein promoted the decrease of SIRT6 and the increase of XBP1 in HPDE cells. Overexpression of SIRT6 slowed down the secretion of inflammatory factors, oxidative stress, apoptosis level, and endoplasmic reticulum stress in HPDE cells. However, XBP1 negatively regulated SIRT6, and XBP1 overexpression partially reversed the regulation of SIRT6 on the above aspects. CONCLUSION: Our study illuminates the role of XBP1 in downregulating SIRT6 in HPDE cells, thereby promoting cellular injury. Inhibiting XBP1 or augmenting SIRT6 levels holds promise in preserving cell function and represents a potential therapeutic avenue in the management of AP.

TSG Targeting KDM5A Affects Osteogenic Differentiation of Bone Mesenchymal Stem Cells Induced by Bone Morphogenetic Protein 2.

OBJECTIVES: To investigate the effect of 2,3,5,4'-tetrahydroxystilbene-2-O-ß-D-glucoside (TSG) on the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and its molecular mechanism. METHODS: After TSG treatment of rBMSCs, alkaline phosphatase (ALP) activity was compared between the drug treatment group and the control group. The effects of TSG on alkaline phosphatase positive cloning and mineralized nodule formation were also detected. Total mRNA and protein were extracted, and the effects of TSG on the expression levels of osteopontin (OPN), osteocalcin (OCN), Runt-related transcription factor 2 (Runx2), Osterix, and Col1a1 were detected by real-time fluorescence quantitative PCR. Western blotting was used to detect the inhibitory effect of TSG on KDM5A. BMSCs were transfected with small interfering RNA (siRNA) targeting KDM5A (si-KMD5A) and pcDNA3.1 KMD5A. RESULTS: TSG significantly increased the activity of ALP, the number of alkaline phosphatase clones, and calcified nodule formation. The OPN, OCN, Runx2, and Osterix expression levels were significantly increased among the osteoblasts after TSG treatment. A mechanistic study showed that the effect of TSG is realized by inhibiting KDM5A. CONCLUSIONS: KDM5A signaling may be involved in the regulation of osteogenic differentiation of rBMSCs. TSG can promote osteogenic differentiation and maturation of rBMSCs at 0.1-50 µmol/L. The mechanism of action was realized by inhibiting the expression of KDM5A.

High Polymorphism in the Dmrt2a Gene Is Incompletely Sex-Linked in Spotted Scat, Scatophagus argus.

Unlike mammals and birds, many fishes have young sex chromosomes, providing excellent models to study sex chromosome differentiation at early stages. Previous studies showed that spotted scat possesses an XX-XY sex determination system. The X has a complete Dmrt3 copy (termed normal) and a truncated copy of Dmrt1 (called Dmrt1b), while the Y has the opposite (normal Dmrt1, which is male-specific, and a truncated Dmrt3 called Dmrt3△-Y). Dmrt1 is the candidate sex determination gene, while the differentiation of other sex-linked genes remains unknown. The spotted scat has proven to be a good model to study the evolution of sex chromosomes in vertebrates. Herein, we sequenced a neighbor gene of this family, Dmrt2, positioned farther from Dmrt1 and closer to Dmrt3 in the spotted scat, and analyzed its sequence variation and expression profiles. The physical locations of the three genes span across an estimated size of >40 kb. The open reading frames of Dmrt2a and its paralog Dmrt2b are 1578 bp and 1311 bp, encoding peptides of 525 and 436 amino acid residues, respectively. Dmrt2a is positioned close to Dmrt3 but farther from Dmrt1 on the same chromosome, while Dmrt2b is not. Sequence analysis revealed several mutations; insertions, and deletions (indels) on Dmrt2a non-coding regions and single-nucleotide polymorphisms (SNPs) on the Dmrt2a transcript. These indels and SNPs are sex-linked and showed high male heterogeneity but do not affect gene translation. The markers designed to span the mutation sites tested on four different populations showed varied concordance with the genetic sexes. Dmrt2a is transcribed solely in the gonads and gills, while Dmrt2b exists in the gonads, hypothalamus, gills, heart, and spleen. The Dmrt2a and Dmrt2b transcripts are profoundly expressed in the male gonads. Analyses of the transcriptome data from five other fish species (Hainan medaka (Oryzias curvinotus), silver sillago (Sillago sihama), Nile tilapia (Oreochromis niloticus), Hong Kong catfish (Clarias fuscus), and spot-fin porcupine fish (Diodon hystrix)) revealed testes-biased expression of Dmrt1 in all, similar to spotted scat. Additionally, the expression of Dmrt2a is higher in the testes than the ovaries in spotted scat and Hainan medaka. The Dmrt2a transcript was not altered in the coding regions as found in Dmrt1 and Dmrt3 in spotted scat. This could be due to the functional importance of Dmrt2a in development. Another possibility is that because Dmrt2a is positioned farther from Dmrt1 and the chromosome is still young, meaning it is only a matter of time before it differentiates. This study undeniably will aid in understanding the functional divergence of the sex-linked genes in fish.

Homozygous Mutation of gsdf Causes Infertility in Female Nile Tilapia (Oreochromis niloticus).

Gonadal somatic cell-derived factor (Gsdf) is a member of the TGF-ß superfamily, which exists mainly in fishes. Homozygous gsdf mutations in Japanese medaka and zebrafish resulted in infertile females, and the reasons for their infertility remain unknown. This study presents functional studies of Gsdf in ovary development using CRISPR/Cas9 in Nile tilapia (Oreochromis niloticus). The XX wild type (WT) female fish regularly reproduced from 12 months after hatching (mah), while the XX gsdf-/- female fish never reproduced and were infertile. Histological observation showed that at 24 mah, number of phase IV oocyte in the XX gsdf-/- female fish was significantly lower than that of the WT fish, although their gonadosomatic index (GSI) was similar. However, the GSI of the XX gsdf-/- female at 6 mah was higher than that of the WT. The mutated ovaries were hyperplastic with more phase I oocytes. Transcriptome analysis identified 344 and 51 up- and down-regulated genes in mutants compared with the WT ovaries at 6 mah. Some TGF-ß signaling genes that are critical for ovary development in fish were differentially expressed. Genes such as amh and amhr2 were up-regulated, while inhbb and acvr2a were down-regulated in mutant ovaries. The cyp19a1a, the key gene for estrogen synthesis, was not differentially expressed. Moreover, the serum 17ß-estradiol (E2) concentrations between XX gsdf-/- and WT were similar at 6 and 24 mah. Results from real-time PCR and immunofluorescence experiments were similar and validated the transcriptome data. Furthermore, Yeast-two-hybrid assays showed that Gsdf interacts with TGF-ß type II receptors (Amhr2 and Bmpr2a). Altogether, these results suggest that Gsdf functions together with TGF-ß signaling pathway to control ovary development and fertility. This study contributes to knowledge on the function of Gsdf in fish oogenesis.

Process tracing of PCDD/Fs from economizer to APCDs during solid waste incineration: Re-formation and transformation mechanisms.

The emission of PCDD/Fs is a crucial factor for the aggravation of the Not-In-My-Back-Yard (NIMBY) syndrome, especially for the incineration plants that fail to meet the emission standard. It is well known that physicochemical processes in the boiler can notably affect the discharge of dioxins, especially under transient, non-steady conditions. However, few studies paid attention to the important operational parameters that influence PCDD/Fs formation and transformation in the boiler when an incinerator is in its daily steady operation. In this study, 36 samples were analyzed to achieve process tracing of PCDD/Fs. The concentration, congener profile and vapor/solid partitions of PCDD/Fs from the economizer to air pollution control devices (APCDs) under two typical steady conditions were investigated. Results indicated that increasing air supply aggravated the formation of PCDD/Fs, disturbed the vapor/solid partitions, and triggered a substandard emission. Quantitative structure-activity relationship (QSAR) modeling was firstly performed for the formation mechanism and orbital energy factors were identified as dominating factors. Besides, the removal rates of PCDD/Fs significantly correlated with the saturated vapor pressure and proportions of different isomers. This study is beneficial for operators to optimize relevant operational parameters of the incineration plants so as to get rid of substandard problems.

A Chromosome-Level Genome Assembly of the Spotted Scat (Scatophagus argus).

The spotted scat, Scatophagus argus is a member of the family Scatophagidae found in Indo-Pacific coastal waters. It is an emerging commercial aquaculture species, particularly in East and Southeast Asia. In this study, the first chromosome-level genome of S. argus was constructed using PacBio and Hi-C sequencing technologies. The genome is 572.42 Mb, with a scaffold N50 of 24.67 Mb. Using Hi-C data, 563.28 Mb (98.67% of the genome) sequences were anchored and oriented in 24 chromosomes, ranging from 12.57 Mb to 30.38 Mb. The assembly is of high integrity, containing 94.26% conserved single-copy orthologues, based on BUSCO analysis. A total of 24,256 protein-coding genes were predicted in the genome, and 96.30% of the predicted genes were functionally annotated. Evolutionary analysis showed that S. argus diverged from the common ancestor of Japanese puffer (Takifugu rubripes) approximately 114.8 Ma. The chromosomes of S. argus showed significant correlation to T. rubripes chromosomes. A comparative genomic analysis identified 49 unique and 90 expanded gene families. These genomic resources provide a solid foundation for functional genomics studies to decipher the economic traits of this species.

Effect of Er:YAG Laser Etching on the Shear Bond Strength and Microleakage of Self-Glazed Zirconia Ceramics.

Objective: To investigate the effect of Er:YAG laser irradiation on the shear bond strength (SBS) and microleakage of self-glazed zirconia (SZ) ceramics. Background: SZ is a novel type ceramic; laser irradiation has started to be used in the surface treatment of different ceramics, while SZ has been rarely studied to improve the bond quality. Methods: One hundred twenty blocks (5 mm × 5 mm × 5 mm) of SZ ceramics were produced and split into eight groups following different surface treatments (n = 15): Group A: no treatment; Group B: standard grid processing; and Group C-H: different Er:YAG laser power settings (100, 200, 300, 400, 500, and 600 mJ). Ten blocks of each group received the measurement of SBS and fracture mode analysis, three blocks underwent the evaluation of the microleakage depths, and the other two blocks were observed under the scanning electronic microscopy (SEM). Results: Group F obtained the highest SBS and the lowest microleakage depth without damaging the ceramic surface structure, which was statistically significant compared with the control group and gridding group (p < 0.05), whereas the difference was not statistically significant (p > 0.05) between group E and group F. The results of bonding performance were consistent with failure types and observation of surface characterizations in SEM images. Conclusions: According to the results here, Er:YAG irradiation had effect on surface treatment. In addition, 400 mJ Er:YAG could increase the SBS and decrease the microleakage depth on SZ ceramics without damaging the surface structure.

From NIMBY to BIMBY: An evaluation of aesthetic appearance and social sustainability of MSW incineration plants in China.

The Not-In-My-BackYard (NIMBY) claims caused by the rapid expansion of waste incineration in China make stakeholders pay more attention to the environmental and social impact. Nowadays, the environmental impact is under control of the whole society while the social sustainability is often neglected. As the social sustainability is vital to the public acceptance and conducive to convert NIMBY claims to Beauty-In-My-BackYard (BIMBY) synergy, all stakeholders desire to know the gap but lack evaluation method. This paper proposes a quantitative evaluation system for the aesthetic appearance of MSW incineration plants for the first time. It uses aesthetic appearance to measure the social sustainability of MSW incineration plants. Real-world photos of 177 incineration plants in China were collected to support the evaluation using weighted sum method. The weights of factors contributing to the aesthetic appearance were obtained by AHP. The process of pairwise comparison in AHP was conducted by an online questionnaire survey involving more than 100 interviewees in various professions. It is evaluated that the aesthetic appearance is not correlated with the pollution control ability. The spatial distribution of different levels of aesthetic appearance shows that eastern provinces should pay more attention to the improvement of old incineration plants. As case studies, the designs of four typical plants are analyzed. The analysis results reveal the gap between NIMBY plants and BIBMY plants. More importantly, they can contribute to push forward the improvements of aesthetic appearance, social sustainability, and public acceptance for MSW incineration plants in China.

Genome Survey of Male and Female Spotted Scat (Scatophagus argus).

The spotted scat, Scatophagus argus, is a species of fish that is widely propagated within the Chinese aquaculture industry and therefore has significant economic value. Despite this, studies of its genome are severely lacking. In the present study, a genomic survey of S. argus was conducted using next-generation sequencing (NGS). In total, 55.699 GB (female) and 51.047 GB (male) of high-quality sequence data were obtained. Genome sizes were estimated to be 598.73 (female) and 597.60 (male) Mbp. The sequence repeat ratios were calculated to be 27.06% (female) and 26.99% (male). Heterozygosity ratios were 0.37% for females and 0.38% for males. Reads were assembled into 444,961 (female) and 453,459 (male) contigs with N50 lengths of 5,747 and 5,745 bp for females and males, respectively. The average guanine-cytosine (GC) content of the female genome was 41.78%, and 41.82% for the male. A total of 42,869 (female) and 43,283 (male) genes were annotated to the non-redundant (NR) and SwissProt databases. The female and male genomes contained 66.6% and 67.8% BUSCO core genes, respectively. Dinucleotide repeats were the dominant form of simple sequence repeats (SSR) observed in females (68.69%) and males (68.56%). Additionally, gene fragments of Dmrt1 were only observed in the male genome. This is the first report of a genome-wide characterization of S. argus.

Expression and transcriptional regulation of gsdf in spotted scat (Scatophagus argus).

Gonadal soma-derived factor (Gsdf) is critical for testicular differentiation and early germ cell development in teleosts. The spotted scat (Scatophagus argus), with a stable XX-XY sex-determination system and the candidate sex determination gene dmrt1, provides a good model for understanding the mechanism of sex determination and differentiation in teleosts. In this study, we analyzed spotted scat gsdf tissue distribution and gene expression patterns in gonads, as well as further analysis of transcriptional regulation. Tissue distribution analysis showed that gsdf was only expressed in testis and ovary. Real-time PCR showed that both gsdf and dmrt1 were expressed significantly higher in testes at different phases (phase III, IV and V) compared to ovaries at phase II, III and IV, while gsdf was expressed significantly higher in phase II ovaries than those of phase III and IV. Western blot analysis also showed that Gsdf was more highly expressed in the testis than ovary. Immunohistochemistry analysis showed that Gsdf was expressed in Sertoli cells surrounding spermatogonia in the testis, while it was expressed in the somatic cells surrounding the oogonia of the ovary. Approximately 2.7 kb of the 5' upstream region of gsdf was cloned from the spotted scat genomic DNA and in silico promoter analysis revealed the putative transcription factor binding sites of Dmrt1 and Sf1. The luciferase reporter assay, using the human embryonic kidney cells, demonstrated that Dmrt1 activated gsdf expression in a dose-dependent manner in the presence of Sf1 in spotted scat. These results suggest that Gsdf could play a role in regulating the development of spermatogonia and oogonia, and also participate in male sex differentiation by acting as a downstream gene of Dmrt1 in spotted scat.

Pyrroloquinoline quinone plays an important role in rescuing Bmi-1-/- mice induced developmental disorders of teeth and mandible--anti-oxidant effect of pyrroloquinoline quinone.

To investigate whether pyrroloquinoline quinine (PQQ) plays an important role in rescuing Bmi-1-/- mice induced developmental disorders of teeth and mandible by regulating oxidative stress. We fed Bmi-1-/- mice a diet supplemented with PQQ (BKO+PQQ), BKO mice with normal diet (BKO) and wild type mice with normal diet (WT) as controls. We compared the differences of dental, mandibular phenotype by means of X-ray photography, micro CT scanning and three-dimensional reconstruction, HE staining, histochemistry, immunoistohemistry, TUNEL staining, Western blot and Flow cytometry in three groups of animals. Results showed that BKO+PQQ mice increased morphology of teeth and mandible, decreased X-ray transmittance, and increased bone density compared with BKO mice. Results also showed that the teeth volume and the dentin sialoprotein (DSP) immunopositive areas, the cortical thickness, alveolar bone volume, osteoblast number and activity, and alkaline phosphatase (ALP), Osteocalcin (OCN) and type I collagen (Col 1) were all reduced significantly in BKO mice compared with their wild-type littermates, whereas these parameters were increased significantly in BKO+PQQ mice compared with BKO mice. Our study indicated that, compared BKO mice, PCNA positive cells percentage of mandibular first molar epithelial root sheath area significantly increased in BKO+PQQ mice, and TUNEL positive cells percentage was significantly decreased. Further studies showed that supplemental PQQ played a role in anti-osteoporosis of teeth and mandible by up-regulating anti-oxidant capacity, inhibiting oxidative stress and reducing DNA damage, down-regulating CDKI proteins levels, and decreasing cell apoptosis. This study demonstrated that PQQ played an important role in rescuing mandible osteoporosis and disorder of teeth development in BKO mice by promoting osteoblastic bone formation of mandibular alveolar bone, inhibiting osteoclastic bone resorption, promoting odontoblast cell proliferation of epithelial root sheath area, inhibiting cell apoptosis, scavenging ROS.

Near-infrared and mid-infrared semiconductor broadband light emitters.

Semiconductor broadband light emitters have emerged as ideal and vital light sources for a range of biomedical sensing/imaging applications, especially for optical coherence tomography systems. Although near-infrared broadband light emitters have found increasingly wide utilization in these imaging applications, the requirement to simultaneously achieve both a high spectral bandwidth and output power is still challenging for such devices. Owing to the relatively weak amplified spontaneous emission, as a consequence of the very short non-radiative carrier lifetime of the inter-subband transitions in quantum cascade structures, it is even more challenging to obtain desirable mid-infrared broadband light emitters. There have been great efforts in the past 20 years to pursue high-efficiency broadband optical gain and very low reflectivity in waveguide structures, which are two key factors determining the performance of broadband light emitters. Here we describe the realization of a high continuous wave light power of >20 mW and broadband width of >130 nm with near-infrared broadband light emitters and the first mid-infrared broadband light emitters operating under continuous wave mode at room temperature by employing a modulation p-doped InGaAs/GaAs quantum dot active region with a 'J'-shape ridge waveguide structure and a quantum cascade active region with a dual-end analogous monolithic integrated tapered waveguide structure, respectively. This work is of great importance to improve the performance of existing near-infrared optical coherence tomography systems and describes a major advance toward reliable and cost-effective mid-infrared imaging and sensing systems, which do not presently exist due to the lack of appropriate low-coherence mid-infrared semiconductor broadband light sources.

InAs/GaAs Quantum Dot Dual-Mode Distributed Feedback Laser Towards Large Tuning Range Continuous-Wave Terahertz Application.

In this paper, a laterally coupled distributed feedback (LC-DFB) laser based on modulation p-doped multiple InAs/GaAs quantum dot (QD) structures has been fabricated. The device exhibits a high side-mode suppression ratio (SMSR) of > 47 dB and a high thermal stability of dλ/dT = 0.092 nm/K under continuous-wave (CW) operation, which is mainly attributed to the high material gain prepared by modulation p-doping and rapid thermal annealing (RTA) process, and the significantly reduced waveguide losses by shallow-etched gratings and its close proximity to the laser ridge feature in the LC-DFB laser. With this superior performance of the DFB laser, the wide tunable dual-wavelength lasing operation has been obtained by delicately defining different periods for the grating structures on the two sides of the laser ridge or combining the reduced laser cavity length. The wavelength spacing between the two lasing modes can be flexibly tuned in a very wide range from 0.5 to 73.4 nm, corresponding to the frequency difference from 0.10 to 14 THz, which is the largest tuning range by the utilization of single device and hence providing a new opportunity towards the generation of CW THz radiation.