3D-Printed Hydrogels with High-Strength and Anisotropy Mediated by Chain Rigidity.

Extrusion-based 3D printing is a facile technology to construct complex structures of hydrogels, especially for tough hydrogels that have shown demonstrated potential in load-bearing materials and tissue engineering. However, 3D-printed hydrogels often possess mechanical properties that do not guarantee their usage in tissue-mimicking, load-bearing components, and motion sensors. This study proposes a novel strategy to construct high-strength and anisotropic Fe3+ cross-linked poly(acrylamide-co-acrylic acid)/sodium alginate double network hydrogels. The semi-flexible sodium alginate chains act as a "conformation regulator" to promote the formation of strong intermolecular interactions between polymer chains and lock the more extended conformation exerted by the pre-stretch, enabling the construction of 3D-printed hydrogel structures with high orientation. The equilibrated anisotropic hydrogel filaments with a water content of 50-60 wt.% exhibit outstanding mechanical properties (tensile strength: 9-44 MPa; elongation at break: 120-668%; Young's modulus: 7-62 MPa; toughness: 26-52 MJ m- 3). 3D-printed anisotropic hydrogel structures with high mechanical performance show demonstrated potential as loading-bearing structures and electrodes of flexible triboelectric nanogenerators for versatile human motion sensing.

Soluble carbon source recovery using preconditioning coagulants for applicable short-term fermentation of waste activated sludge in WWTPs.

A huge production of waste activated sludge (WAS) has been a burden for wastewater treatment plants (WWTPs) with high disposal cost and little benefit back to wastewater purification. The short-chain fatty acids (SCFAs) produced by a short-term acidogenic fermentation of WAS before methane production have been proven to be a high-quality carbon source available for microbial denitrification process. The dual purpose of full recovery of fermentation liquid products and facilitating disposal of residual solid waste necessitate an efficient solid-liquid separation process of short-term fermentation liquid. The transformation and loss of various soluble carbon sources between solid and liquid are very important issues for carbon recovery efficiency when combining short-term fermentation and sludge dewatering in WWTPs. Here we testified the three conventional preconditioning coagulants, Polyferric Sulfate (PFS), Poly Aluminum Chloride (PAC) and Polyacrylamide (PAM), to improve the efficiency of subsequent solid-liquid separation. The results show that conversion yield of SCFAs in the liquid phase of sludge after short-term fermentation was 195 mg COD/g VSS, when using the coagulants PFS, PAC, and PAM for recovery, the recovery ratio was 79.5%, 82.0%, and 85.9%, respectively, while the dewaterability could be improved after preconditioning short-term fermentation sludge. The complexation of Al3+/Fe3+ in metal coagulants with carboxyl groups of SCFA demonstrated by Density Functional Theory calculation led to small part of soluble carbons co-migration to the solid phase, mainly a loss of high molecular weight organic compounds (carbohydrate, proteins, humic acids), while the application of PAM had little impact on carbon recovery. Economic calculations further showed PAM preconditioning short-term fermentation liquid of WAS could achieve higher recovery benefits.

Review of Sensor-Based Subgrade Distress Identifications.

The attributes of diversity and concealment pose formidable challenges in the accurate detection and efficacious management of distresses within subgrade structures. The onset of subgrade distresses may precipitate structural degradation, thereby amplifying the frequency of traffic incidents and instigating economic ramifications. Accurate and timely detection of subgrade distresses is essential for maintaining and repairing road sections with existing distresses. This helps to prolong the service life of road infrastructure and reduce financial burden. In recent years, the advent of numerous novel technologies and methodologies has propelled significant advancements in subgrade distress detection. Therefore, this review delineates a concentrated examination of subgrade distress detection, methodically consolidating and presenting various techniques while dissecting their respective merits and constraints. By furnishing comprehensive guidance on subgrade distress detection, this review facilitates the expedient identification and targeted treatment of subgrade distresses, thereby fortifying safety and enhancing durability. The pivotal role of this review in bolstering the construction and operational facets of transportation infrastructure is underscored.

Helical Cage Rotors Switched on by Brake Molecule with Variable Fluorescence and Circularly Polarized Luminescence.

While chiral molecular rotors have unique frames and cavities to possibly generate switchable chiroptical functions, it still remains a formidable challenge to precisely restrict their rotations to activate certain functions such as fluorescence as well as circularly polarized luminescence (CPL), which are strongly related to the local molecular rotations. Herein, we design a pair of enantiopure helical cage rotors, which emit light neither at the molecular state nor in the crystal or aggregation states, although they contain luminophore groups. However, upon mounting with fluoroaromatic borane (TFPB) as a molecular brake, the phenyl rotation of the helical cage can be effectively hindered and fluorescence and CPL activities of the molecular cage are switched on. Crystal structure analysis reveals that the rotation is restricted through synergistic B-O-H-N bonding and a fluoroaromatic-aromatic (ArF-Ar) dipole interaction. Moreover, the helical cages are switched on stepwise with color-variable fluorescence and CPL by the inner brake in the molecular state and the outer brake in the supramolecular assemblies, respectively. This work not only provides the design idea of chiroptical molecular rotors but also unveils how fluorescence and CPL could be generated in cage rotor systems.

Multiplex gene knockout raises Ala-Gln production by Escherichia coli expressing amino acid ester acyltransferase.

L-Alanyl-L-Glutamine (Ala-Gln) is a common parenteral nutritional supplement. In our previous study, the recombinant whole-cell catalyst Escherichia coli BL21(DE3) overexpressing α-amino acid ester acyltransferase (BPA) to produce Ala-Gln has high activity and has been applied to large-scale production experiments. However, the degradation of Ala-Gln is detected under prolonged incubation, and endogenous broad-spectrum dipeptidase may be the primary cause. In this study, a CRISPR-Cas9 method was used to target pepA, pepB, pepD, pepN, dpp, and dtp to knock out one or more target genes. The deletion combination was optimized, and a triple knockout strain BL21(DE3)-ΔpepADN was constructed. The degradation performance of the knockout chassis was measured, and the results showed that the degradation rate of Ala-Gln was alleviated by 48% compared with the control. On this basis, BpADNPA (BPA-ΔpepADN) was built, and the production of Ala-Gln was 129% of the BPA's accumulation, proving that the ΔpepADN knockout conducive to the accumulation of dipeptide. This study will push forward the industrialization process of Ala-Gln production by whole-cell catalyst Escherichia coli expressing α-amino acid ester acyltransferase. KEY POINTS: • Endogenous dipeptidase knockout alleviates the degradation of Ala-Gln by the chassis • The balanced gene knockout combination is pepA, pepD, and pepN • The accumulation of Ala-Gln with BpADNPA was 129% of the control.

Opportunities and challenges of patient-derived models in cancer research: patient-derived xenografts, patient-derived organoid and patient-derived cells.

BACKGROUND: As reported, preclinical animal models differ greatly from the human body. The evaluation model may be the colossal obstacle for scientific research and anticancer drug development. Therefore, it is essential to propose efficient evaluation systems similar to clinical practice for cancer research. MAIN BODY: While it has emerged for decades, the development of patient-derived xenografts, patient-derived organoid and patient-derived cell used to be limited. As the requirements for anticancer drug evaluation increases, patient-derived models developed rapidly recently, which is widely applied in basic research, drug development, and clinical application and achieved remarkable progress. However, there still lack systematic comparison and summarize reports for patient-derived models. In the current review, the development, applications, strengths, and challenges of patient-derived models in cancer research were characterized. CONCLUSION: Patient-derived models are an indispensable approach for cancer research and human health.

Development and validation predictive models of sperm retrieval for azoospermic men undergoing testicular sperm aspiration: a multicentre, retrospective, cohort study.

PURPOSE: Testicular sperm aspiration (TESA) is widely used to retrieve sperm from testis. Diagnostic testicular biopsy should not be routinely performed for azoospermia. Therefore, a good predictive model is needed before TESA. METHODS: A total of 1972 azoospermia patients constituted the modelling set, and 260 azoospermia patients from two other centres constituted the validation set. An integrated predictive model was built using logistic regression. Receiver operating characteristic (ROC), calibration and decision curve analyses were performed to evaluate the performance of follicle-stimulating hormone (FSH), semen volume, testicular volume and the integrated model. RESULTS: The FSH level was the best univariate predictor for successful sperm retrieval (SSR) and was better than semen volume and testicular volume alone (p<0.001, threshold 6.17 IU/L, modelling set area under receiver operating characteristic curve (AUC) 0.80, accuracy 0.79; validation set AUC 0.87, accuracy 0.78). The integrated predictive model had excellent accuracy for predicting SSR (modelling set: AUC 0.93, accuracy 0.89; validation set: AUC 0.96, accuracy: 0.89). Calibration curve analysis indicated that the integrated model calibration was good and better than that of FSH, semen volume and testicular volume alone. Decision curve analysis indicated with a threshold probability between 0.05 and 0.98, the integrated model added more benefit than treating either all or no patients. CONCLUSIONS: The integrated model has excellent discrimination and good calibration. It can help azoospermic men make better decisions before TESA. It should be noted that TESA is not the first-line treatment for non-obstructive azoospermia because of a low sperm retrieval rate.

Formate Dehydrogenase Improves the Resistance to Formic Acid and Acetic Acid Simultaneously in Saccharomyces cerevisiae.

Bioethanol from lignocellulosic biomass is a promising and sustainable strategy to meet the energy demand and to be carbon neutral. Nevertheless, the damage of lignocellulose-derived inhibitors to microorganisms is still the main bottleneck. Developing robust strains is critical for lignocellulosic ethanol production. An evolved strain with a stronger tolerance to formate and acetate was obtained after adaptive laboratory evolution (ALE) in the formate. Transcriptional analysis was conducted to reveal the possible resistance mechanisms to weak acids, and fdh coding for formate dehydrogenase was selected as the target to verify whether it was related to resistance enhancement in Saccharomyces cerevisiae F3. Engineered S. cerevisiae FA with fdh overexpression exhibited boosted tolerance to both formate and acetate, but the resistance mechanism to formate and acetate was different. When formate exists, it breaks down by formate dehydrogenase into carbon dioxide (CO2) to relieve its inhibition. When there was acetate without formate, FDH1 converted CO2 from glucose fermentation to formate and ATP and enhanced cell viability. Together, fdh overexpression alone can improve the tolerance to both formate and acetate with a higher cell viability and ATP, which provides a novel strategy for robustness strain construction to produce lignocellulosic ethanol.

Stacked Reticular Frame Boosted Circularly Polarized Luminescence of Chiral Covalent Organic Frameworks.

Chiral covalent organic frameworks (COFs) with circularly polarized luminescence (CPL) are intriguing as advanced chiroptical materials but have not been reported to date. We constructed chiroptical COF materials with CPL activity through the convenient Knoevenagel condensation of formyl-functionalized axially chiral linkers and C3-symmetric 1,3,5-benzenetriacetonitrile. Remarkably, the as-prepared chiral COFs showed high absorption and luminescent dissymmetric factors up to 0.02 (gabs ) and 0.04 (glum ), respectively. In contrast, the branched chiral polymers from the same starting monomers were CPL silent. Structural and spectral characterization revealed that the reticular frame was indispensable for CPL generation via confined chirality transfer. Moreover, reticular stacking boosted the CPL performance significantly due to the interlayer restriction of frame. This work demonstrates the first example of a CPL-active COF and provides insight into CPL generation through covalent reticular chemistry, which will play a constructive role in the future design of high-performance CPL materials.

Excitation-Dependent Circularly Polarized Luminescence from Helical Assemblies Based on Tartaric Acid-Derived Acylhydrazones.

Here, we combined the merits of emergent excitation-dependent (ExD) emission and circularly polarized luminescence to develop an excitation-dependent circularly polarized luminescence (ExD CPL) material showing unique features. A series of acylhydrazones based on a chiral tartaric skeleton was designed and found to self-assemble into helical nanostructures through non-covalent bonds. The helical assemblies showed ExD CPL due to the cooperation of chirality transfer and excited state intramolecular proton transfer (ESIPT). Remarkably, not only the emission wavelength could be tuned by the excitation wavelength but the handedness of CPL could be modulated in an inverted or ON/OFF manner as well, thus leading to the first example of an ExD inverted or ON/OFF switchable CPL system. Time-dependent density functional theory (TD-DFT) calculations were carried out to explain the inversion of ExD CPL. This work provided a new insight into the unprecedented handedness controllable ExD CPL, which showcased a new paradigm of the advanced CPL materials.

Hindered Tetraphenylethylene Helicates: Chiral Fluorophores with Deep-Blue Emission, Multiple-Color CPL, and Chiral Recognition Ability.

New hindered tetraphenylethylene (TPE) helicates with substitution at 2,6-position of phenyl rings were designed and synthesized. Due to the increased hindrance, the TPE helicates emit strong deep-blue to violet fluorescence both in the solid state and in solution, and could be resolved into enantiomers that emit strong and multicolor circularly polarized luminescence (CPL), and exhibit a high enantioselective recognition of chiral tartaric acid and its derivatives. Surprisingly, the derived helicate tetramines possess amino groups with an unpredented planar structure and sp2 -hybridized nitrogen, arousing the change between AIE effect and ACQ phenomenon through photoinduced electron transfer (PET). With advantages of short synthetic route, many modification positions, deep-blue to violet emission, wide CPL tuning, and high chiral recognition ability, the hindered TPE helicates show broad prospects as chiral materials.

Targeting Nestin+ hepatic stellate cells ameliorates liver fibrosis by facilitating TßRI degradation.

BACKGROUND & AIMS: Liver fibrosis is a wound healing response that arises from various aetiologies. The intermediate filament protein Nestin has been reported to participate in maintaining tissue homeostasis during wound healing responses. However, little is known about the role Nestin plays in liver fibrosis. This study investigated the function and precise regulatory network of Nestin during liver fibrosis. METHODS: Nestin expression was assessed via immunostaining and quantitative real-time PCR (qPCR) in fibrotic/cirrhotic samples. The induction of Nestin expression by transforming growth factor beta (TGFß)-Smad2/3 signalling was investigated through luciferase reporter assays. The functional role of Nestin in hepatic stellate cells (HSCs) was investigated by examining the pathway activity of profibrogenic TGFß-Smad2/3 signalling and degradation of TGFß receptor I (TßRI) after interfering with Nestin. The in vivo effects of knocking down Nestin were examined with an adeno-associated virus vector (serotype 6, AAV6) carrying short-hairpin RNA targeting Nestin in fibrotic mouse models. RESULTS: Nestin was mainly expressed in activated HSCs and increased with the progression of liver fibrosis. The profibrogenic pathway TGFß-Smad2/3 induced Nestin expression directly. Knocking down Nestin promoted caveolin 1-mediated TßRI degradation, resulting in TGFß-Smad2/3 pathway impairment and reduced fibrosis marker expression in HSCs. In AAV6-treated murine fibrotic models, knocking down Nestin resulted in decreased levels of inflammatory infiltration, hepatocellular damage, and a reduced degree of fibrosis. CONCLUSION: The expression of Nestin in HSCs was induced by TGFß and positively correlated with the degree of liver fibrosis. Knockdown of Nestin decreased activation of the TGFß pathway and alleviated liver fibrosis both in vitro and in vivo. Our data demonstrate a novel role of Nestin in controlling HSC activation in liver fibrosis. LAY SUMMARY: Liver fibrosis has various aetiologies but represents a common process in chronic liver diseases that is associated with high morbidity and mortality. Herein, we demonstrate that the intermediate filament protein Nestin plays an essential profibrogenic role in liver fibrosis by forming a positive feedback loop with the TGFß-Smad2/3 pathway, providing a potential therapeutic target for the treatment of liver fibrosis.

Repeated subarachnoid administrations of allogeneic human umbilical cord mesenchymal stem cells for spinal cord injury: a phase 1/2 pilot study.

BACKGROUND AIMS: Stem cell transplantation is a potential treatment for intractable spinal cord injury (SCI), and allogeneic human umbilical cord mesenchymal stem cells (hUC-MSCs) are a promising candidate because of the advantages of immune privilege, paracrine effect, immunomodulatory function, convenient collection procedure and little ethical concern, and there is an urgent need to develop a safe and effective protocol regarding their clinical application. METHODS: A prospective, single-center, single-arm study in which subjects received four subarachnoid transplantations of hUC-MSCs (1 × 106 cells/kg) monthly and were seen in follow-up four times (1, 3, 6 and 12 months after final administration) was conducted. At each scheduled time point, safety and efficacy indicators were collected and analyzed accordingly. Adverse events (AEs) were used as a safety indicator. American Spinal Injury Association (ASIA) and SCI Functional Rating Scale of the International Association of Neurorestoratology (IANR-SCIFRS) total scores at the fourth follow-up were determined as primary efficacy outcomes, whereas these two indicators at the remaining time points as well as scores of pinprick, light touch, motor and sphincter, muscle spasticity and spasm, autonomic system, bladder and bowel functions, residual urine volume (RUV) and magnetic resonance imaging (MRI) were secondary efficacy outcomes. Subgroup analysis of primary efficacy indicators was also performed. RESULTS: Safety and efficacy assessments were performed on 102 and 41 subjects, respectively. Mild AEs involving fever (14.1%), headache (4.2%), transient increase in muscle tension (1.6%) and dizziness (1.3%) were observed following hUC-MSC transplantation and resolved thoroughly after conservative treatments. There was no serious AE. ASIA and IANR-SCIFRS total scores revealed statistical increases when compared with the baselines at different time points during the study, mainly reflected in the improvement of pinprick, light touch, motor and sphincter scores. Moreover, subjects showed a continuous and remarkable decrease in muscle spasticity. Regarding muscle spasm, autonomic system, bladder and bowel functions, RUV and MRI, data/imaging at final follow-up showed significant improvements compared with those at first collection. Subgroup analysis found that hUC-MSC transplantation improved neurological functions regardless of injury characteristics, including level, severity and chronicity. CONCLUSIONS: The authors' present protocol demonstrates that intrathecal administration of' allogeneic hUC-MSCs at a dose of 106 cells/kg once a month for 4 months is safe and effective and leads to significant improvement in neurological dysfunction and recovery of quality of life.

Photonic generation of a dual-chirp waveform with an optoelectronic oscillator based on stimulated Brillouin scattering.

A photonic method to generate a dual-chirp microwave waveform (DCMW) is proposed and demonstrated by utilizing a stimulated Brillouin scattering based optoelectronic oscillator and a frequency scanning laser source (FSLS). There are no radio frequency sources or Mach-Zehnder modulators in the proposed structure, which makes the system simple and stable. In the experiment, an alternative scheme is utilized to replace the FSLS, and the DCMW signal with a central frequency of 4.69 GHz is generated; the bandwidth of the generated DCMW signal is up to 7 GHz and the chirp rate up to ±5.3GHz/µs. The autocorrelation and ambiguity function of the generated signal are also investigated and show good performance of pulse compression and reduction of range-Doppler coupling.

mRNA modification orchestrates cancer stem cell fate decisions.

Despite their small numbers, cancer stem cells play a central role in driving cancer cell growth, chemotherapeutic resistance, and distal metastasis. Previous studies mainly focused on how DNA or histone modification determines cell fate in cancer. However, it is still largely unknown how RNA modifications orchestrate cancer cell fate decisions. More than 170 distinct RNA modifications have been identified in the RNA world, while only a few RNA base modifications have been found in mRNA. Growing evidence indicates that three mRNA modifications, inosine, 5-methylcytosine, and N6-methyladenosine, are essential for the regulation of spatiotemporal gene expression during cancer stem cell fate transition. Furthermore, transcriptome-wide mapping has found that the aberrant deposition of mRNA modification, which can disrupt the gene regulatory network and lead to uncontrollable cancer cell growth, is widespread across different cancers. In this review, we try to summarize the recent advances of these three mRNA modifications in maintaining the stemness of cancer stem cells and discuss the underlying molecular mechanisms, which will shed light on the development of novel therapeutic approaches for eradicating cancer stem cells.

Generation of hepatocyte-like cells from human urinary epithelial cells and the role of autophagy during direct reprogramming.

Somatic cells can be directly reprogrammed into other cell lineages, which holds great promise for regenerative medicine. However, low efficiency and obscure mechanism hinder the application of direct reprogramming. Here, we show that overexpressing the hepatic-specific transcription factors (TFs) HNF1α, FOXA3, and GATA4 was sufficient to convert human urinary epithelial cells (hUCs) into induced hepatocyte-like cells (iHeps). The obtained iHeps were confirmed to express various hepatocyte-specific genes with multiple mature hepatocyte functions. Moreover, autophagy-related genes P62, ULK1, BECN1, VPS34, and LC3B were upregulated in the early stage of reprogramming and knockout of P62 and BECN1 in hUCs with CRISPR/Cas9 technology increased the efficiency of direct reprogramming. Collectively, we established a non-invasive approach to convert hUCs into iHeps and provided a glimpse into the role of autophagy in this process.

Proof-of-principle demonstration of measurement-device-independent quantum key distribution based on intrinsically stable polarization-modulated units.

The experimental demonstration of measurement-device-independent quantum key distribution (MDI-QKD) has been widely demonstrated. Thus far, several experimental groups have implemented polarization encoding MDI-QKD but with manual polarization controllers, or polarization modulators that make circular polarization states unstable. Here, we apply an intrinsically stable polarization-modulated unit (PMU) to MDI-QKD so that Alice and Bob can modulate four BB84 polarization states, all of which can be kept stable from even the harsh environment. Moreover, our PMU can provide two operational polarization encoding modes suitable to different application scenarios. A proof-of-principle demonstration of MDI-QKD based on our PMU is implemented with an interference visibility of 46.6%, an average quantum bit error rate of 1.49% for the Z basis and the secure key rate of 4.25 × 10-6 bits per pulse. The proposed study is helpful for building polarization encoding MDI-QKD systems with better stability.

Insights into the key components of bacterial assemblages in typical process units of oily wastewater treatment plants.

To compare the structure of microbial community in the oily wastewater treatment plants (OWWTPs) located in China, and to discern the impacts of environment variables on the variance of microbial community, activated sludge samples from six typical OWWTPs were taken and the structure of microbial community of these six samples were analyzed via Illumina high-throughput sequencing. 18 core genera including Comamonas, Bacillus, Pseudomonas, Thauera, Paenibacillus, etc. were shared by all OWWTPs. Canonical correspondence analysis (CCA) suggested that temperature, oil concentration, DO and pH exhibited significant impacts in shaping the structure of microbial community. Variance partitioning analyses (VPA) illuminated that the most variation in microbial community was contributed to geographic location, explaining 36.4% of the total variations obtained, followed by wastewater characteristics (18.7%) and operational parameters (8.6%). This work offered insights into the structure of microbial community in OWWTPs at different geographic locations and illustrated the correlations between environment variables and microbial community in OWWTPs.

Production of L-alanyl-L-glutamine by immobilized Escherichia coli expressing amino acid ester acyltransferase.

Production of Ala-Gln by the E. coli expressing α-amino acid ester acyltransferase was a promising technical route due to its high enzyme activity, but the continuous production ability still needs to improve. Therefore, the immobilized E. coli expressing α-amino acid ester acyltransferase was applied for the continuous production of Ala-Gln. Four materials were selected as embedding medium for the whole cell entrapment of recombinant bacteria. Calcium alginate beads were found to be the most proper entrapment carrier for production of Ala-Gln. The temperature, pH, and repeatability of the immobilized cell were compared with free cells. Results showed that immobilization cell could maintain a wider range of temperature/pH and better stability than free cell (20-35 °C/pH 8.0-9.0, and 25 °C/pH 8.5, respectively). On this basis, continuous production strategy was put forward by filling the immobilized cell in the tubular reactor with multiple control conditions. The Ala-Gln by immobilization cell achieved the productivity of 2.79 mg/(min*mL-CV) without intermittent time. Consequently, these findings suggest that the immobilization technique has potential applications in the production of Ala-Gln by biotechnological method. KEY POINTS: • Immobilization helps to achieve high efficiency production of Ala-Gln. • Immobilized cells have better stability than free cells. • Sodium alginate is the most suitable immobilized material.

UWB quadruplet signal generation based on a DP-QPSK modulator and a delay-line filter.

A photonic ultra-wideband (UWB) quadruplet signal generation based on a dual-polarization quadrature phase shift keying (DP-QPSK) modulator is presented. A Gaussian sequence is split into four parts and input to the four driving ports of the DP-QPSK. Through polarization rotation and polarization combination, a pair of polarization-orthogonal, polarity-reversed doublet signals are generated from the output of the DP-QPSK modulator. Subsequently, they are injected into a balanced photodetector (BPD) for further differentiation. After the heterodyne detection, a UWB quadruplet signal can be obtained. In this system, four electrical amplifiers are incorporated into the four electrical driving paths to adjust the modulation indices of the DP-QPSK. To attain the optimal spectral power efficiency (SPE), a relationship among the SPE, pulse width, delay time, and the two main modulation indices is created. Consequently, the optimal point is found with an SPE of 53.46%. Then, several impairments brought by the nonideal devices are considered in the simulation system. The distortion caused by impairments is compensated by properly adjusting the devices. The generated spectrum has a SPE of 53.38% and efficiently complies with the Federal Communications Commission (FCC) mask without any low-frequency components exceeding the FCC mask. In addition, on-off keying and pulse position modulation are realized in the system.