Real-time observation of leukocyte-endothelium interactions in tissue-engineered blood vessel

Human cell-based 3D tissue constructs play an increasing role in disease modeling and drug screening. Inflammation, atherosclerosis, and many autoimmune disorders involve the interactions between immune cells and blood vessels. However, it has been difficult to image and model these interactions under realistic conditions. In this study, we fabricated a perfusion and imaging chamber to allow the real-time visualization of leukocyte perfusion, adhesion, and migration inside a tissue-engineered blood vessel (TEBV). We monitored the elevated monocyte adhesion to the TEBV wall and transendothelial migration (TEM) as the TEBV endothelium was activated by the inflammatory cytokine TNF-α. We demonstrated that treatment with anti-TNF-α or an NF-kB signaling pathway inhibitor would attenuate the endothelium activation and reduce the number of leukocyte adhesion (>74%) and TEM events (>87%) close to the control. As the first demonstration of real-time imaging of dynamic cellular events within a TEBV, this work paves the way for drug screening and disease modeling in TEBV-associated microphysiological systems.

Photostable and Biocompatible Fluorescent Silicon Nanoparticles-Based Theranostic Probes for Simultaneous Imaging and Treatment of Ocular Neovascularization

Ocular neovascularization can result in devastating diseases that lead to marked vision impairment and eventual visual loss. In clinical implementation, neovascular eye diseases are first diagnosed by fluorescein angiography and then treated by multiple intravitreal injections, which nevertheless involves vision-threatening complications, as well as lack of real-time monitoring disease progression and timely assessment of therapeutic outcomes. To address this critical issue, we herein present a kind of theranostic agents made of peptide-functionalized silicon nanoparticles (SiNPs), suitable for simultaneous ocular neovascularization imaging and therapy. Typically, in addition to negligible toxicity and high specific binding ability to human retinal microvascular endothelial cells tube formation, the cyclo-(Arg-Gly-Asp-d-Tyr-Cys) ( c-(RGDyC))-conjugated SiNPs (SiNPs-RGD) features efficacious antiangiogenic ability in wound healing migration, transwell migration, transwell invasion, and tube formation assays. Taking advantage of these unique merits, we further employ the SiNPs-RGD for labeling angiogenic blood vessels and neovascularization suppression, demonstrating obvious inhibition of new blood vessels formation in mouse corneas. These results suggest the SiNPs-RGD as a novel class of high-quality theranostic probes is suitable for simultaneous diagnosis and treatment in ocular neovascular diseases.

Wastewater management approach in an industrial park

Many industrial parks adopt a two-tier wastewater management framework whereby tenants and the park are required to build satellite and centralized wastewater treatment facilities, respectively. Due to the diversity of industrial wastewaters, the treatment process scheme in the public centralized wastewater treatment plant (WWTP) may not suit the characteristics of all effluents discharged from the tenants. In consideration of varying wastewater biodegradability, the treatment scheme in a centralized WWTP is advised to install two series of treatment processes. In detail, various effluents from the tenants shall be commingled according to their levels of biodegradability. For the non-biodegradable streams, advanced oxidation processes shall be applied in addition to biological treatments. To facilitate the grouping of effluents, each effluent will be evaluated for its biodegradability. An analytical protocol derived from OECD standard (TG302B) was developed and found effective for biodegradability assessment. A case study is described in this paper to showcase the methodology.

Pinewood nematode infection alters root mycoflora of Pinus tabulaeformis Carr

AIMS

This study investigates pinewood nematode's impacts on root mycoflora of Pinus tabulaeformis.

METHODS AND RESULTS

The biomass, colonization rate, community structure and diversity of root-associated fungi were investigated in pinewood nematode-infected and nematode-noninfected P. tabulaeformis. The results indicated that the roots of P. tabulaeformis were colonized highly by root-associated fungi, mainly ectomycorrhizal fungi (ECMF) and dark septate endophytes. Infection of pinewood nematode was associated with a significant (P < 0·05) decrease in root colonization rates by ECMF, dark septate endophytes and total hyphae, as well as in fungal biomass in the roots. Illumina MiSeq sequences of tagged amplicons of 18S rDNA region revealed Basidiomycota (65·70%) and Ascomycota (34·14%) as the dominant root-associated fungi in roots of P. tabulaeformis. Among the detected operational taxonomic units (OTUs), ECMF and dark septate endophytes exhibited a higher relative abundance in trees infected by pinewood nematode compared with noninfected ones.

CONCLUSIONS

The infection of pinewood nematode altered the composition and OTU abundance of root-associated fungi community in P. tabulaeformis roots with a decrease in the biomass, species richness and diversity of root-associated fungi, as well as in the colonization rates and abundance of ECMF and dark septate endophytes.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study is an important contribution for better understanding the interaction between pine wilt disease and root-associated fungi.

Comparative cytotoxicity and apoptotic pathways induced by nanosilver in human liver HepG2 and L02 cells

Silver nanoparticles are used in many commercial products in daily life. Exposure to nanosilver has hepatotoxic effects in animals. This study investigated the cytotoxicity associated with polyvinylpyrrolidone-coated nanosilver (23.44 ± 4.92 nm in diameter) exposure in the human hepatoma cell line (HepG2) and normal hepatic cell line (L02), and the molecular mechanisms induced by nanosilver in HepG2 cells. Nanosilver, in doses of 20-160 μg mL^-1 for 24 and 48 h, reduced cell viability in a dose- and time-dependent manner and induced cell membrane leakage and mitochondria injury in both cell lines; these effects were more pronounced in HepG2 cells than in L02 cells. Intracellular oxidative stress was documented by reactive oxygen species (ROS) being generated in HepG2 cells but not in L02 cells, an effect possibly due to differential uptake of nanosilver by cancer cells and normal cells. In HepG2 cells, apoptosis was documented by finding that ROS triggered a decrease in mitochondrial membrane potential, an increase in cytochrome c release, activation of caspase 3 and caspase 9, and a decrease in the ratio of Bcl-2/Bax. Furthermore, nanosilver activated the Fas death receptor pathway by downregulation of nuclear factor-κB and activation of caspase 8 and caspase 3. These results suggest that apoptosis induced by nanosilver in HepG2 cells is mediated via a mitochondria-dependent pathway and the Fas death receptor pathway. These findings provide toxicological and mechanistic information that can help in assessing the effects of nanosilver in biological systems, including the potential for anticancer activities.

Abstract GS1-05: Tandem duplicator phenotypes define 50% of triple negative breast cancers

Background. We recently discovered a unique chromotype, the Tandem Duplicator Phenotype (TDP), characterized by hundreds of somatic tandem duplications (TDs) scattered throughout the genome of a large percentage of triple negative breast cancers (TNBCs). Importantly, we observed that the TDP associates with a better response to cisplatin therapy in vitro and in vivo, suggesting that it is a tractable and quantitative biomarker of response to platinum-based therapy. Here, we expand on our initial findings by analyzing Whole-Genome (WG) sequences of over 2,700 tumors.

Methods. TD coordinates from WG sequences relative to 2717 tumors were assembled from over 30 independent studies representing several cancer types, including 254 TNBCs. WG sequencing of mouse breast tumors was carried out using standard Illumina protocols. The number, distribution and span-size of somatic TDs from a training set of 992 tumors were used to develop a TDP classifier that identifies highly recurrent but clearly distinct TDP profiles. The TDP classifier was then applied to the remaining tumor sequences. WG mutation and copy number datasets were investigated to identify the genetic drivers associated with each TDP profile, and the genomic consequences of different TDPs were evaluated through identification of genomic hotspots for gene duplication and transection.

Results. We describe six different TDPs featuring distinct TD span size distributions, with peaks at 10Kb (group 1), 300Kb (group 2) and 3Mb (group 3), or different combinations of these (mix12, mix13 and mix23). More than half of all TNBC display a TDP. Of these, 55% classify as group 1, 14% as group 2 and 15% as group mix12. Whereas all TDP groups show a higher TP53 mutation rate compared to non-TDP tumors, each TDP profile is characterized by specific additional gene perturbations, with loss of BRCA1 occurring in groups 1, mix12 and mix13; CCNE1 amplification in group 2; and CDK12 mutations in group mix23. We show that different TDPs are subject to the perturbation of specific oncogenic networks resulting from the duplication of oncogenes by larger TDs (&gt;300Kb) or the disruption of tumor suppressors via double transections by shorter TDs (10Kb). Indeed, tumor suppressor genes such as PTEN, RB1 and MLL3 are frequently disrupted by TDs in TNBC TDP group 1 tumors, whereas TNBC TDP group 2 tumors commonly feature duplication of oncogenes such as MYC and MALAT1. Finally, through WG analyses of 18 mouse models (GEMMs) of breast cancer, we provide the first mechanistic evidence of the driving role of conjoint loss of TP53 and BRCA1, but not of BRCA2, in inducing the TDP group 1 profile.

Conclusions. Our study shows a definitive genetic induction of one specific form of TDP (group 1) characterized by 10kb TD span. Different TDP profiles are characterized by alternative somatic genetic origins but always couple with disruptive TP53 mutations. The consequences of the massive TD formation in TDP TNBCs suggest a systems strategy to tumor induction involving heterogeneous combinations of oncogenes and tumor suppressors. That these TDP forms, accounting for ˜50% of TNBC, are associated with significant sensitivity to cisplatin suggest that this chromotype may identify TNBC patients who would benefit from upfront platinum-based chemotherapy.

Citation Format: Liu ET, Menghi F, Barthel F, Yadav V, Tang M, Ji B, Carter G, Jonkers J, Verhaak R. Tandem duplicator phenotypes define 50% of triple negative breast cancers [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr GS1-05.

Controllable mode transformation in perfect optical vortices

We report a novel method to freely transform the modes of a perfect optical vortex (POV). By adjusting the scaling factor of the Bessel-Gauss beam at the object plane, the POV mode transformation can be easily controlled from circle to ellipse with a high mode purity. Combined with the modulation of the cone angle of an axicon, the ellipse mode can be freely adjusted along the two orthogonal directions. The properties of the "perfect vortex" are experimentally verified. Moreover, fractional elliptic POVs with versatile modes are presented, where the number and position of the gaps are controllable. These findings are significant for applications that require the complex structured optical field of the POV.

Galaxy growth in a massive halo in the first billion years of cosmic history

According to the current understanding of cosmic structure formation, the precursors of the most massive structures in the Universe began to form shortly after the Big Bang, in regions corresponding to the largest fluctuations in the cosmic density field. Observing these structures during their period of active growth and assembly-the first few hundred million years of the Universe-is challenging because it requires surveys that are sensitive enough to detect the distant galaxies that act as signposts for these structures and wide enough to capture the rarest objects. As a result, very few such objects have been detected so far. Here we report observations of a far-infrared-luminous object at redshift 6.900 (less than 800 million years after the Big Bang) that was discovered in a wide-field survey. High-resolution imaging shows it to be a pair of extremely massive star-forming galaxies. The larger is forming stars at a rate of 2,900 solar masses per year, contains 270 billion solar masses of gas and 2.5 billion solar masses of dust, and is more massive than any other known object at a redshift of more than 6. Its rapid star formation is probably triggered by its companion galaxy at a projected separation of 8 kiloparsecs. This merging companion hosts 35 billion solar masses of stars and has a star-formation rate of 540 solar masses per year, but has an order of magnitude less gas and dust than its neighbour and physical conditions akin to those observed in lower-metallicity galaxies in the nearby Universe. These objects suggest the presence of a dark-matter halo with a mass of more than 100 billion solar masses, making it among the rarest dark-matter haloes that should exist in the Universe at this epoch.

[Analysis of 2 204 stillbirths in 11 hospitals of Guangdong province]

Objective: To analyze the incidence and causes of stillbirth in 11 hospitals of Guangdong province, and to explore the appropriate interventions. Methods: Clinical data of stillbirth in 11 hospitals of Guangdong province were collected from January 2014 to December 2016. The gestational weeks, causes, maternal conditions and other factors were analyzed. Results: (1) From 2014 to 2016, 103 472 newborns were delivered in the 11 hospitals, and the number of stillbirth was 2 204, with the incidence of 2.13%. Among them, 0.71%(738/103 472) was therapeutic induction, 1.42%(1 066/103 472) was natural stillbirth. At different gestational age (<28 weeks, 28-<37 weeks and ≥37 weeks), the incidence of stillbirth was 55.63% (1 226/2 204), 28.45% (627/2 204) and 15.92% (351/2 204), respectively, with statistically significant difference (P<0.01). (2) For stillbirth<28 weeks, the first reason was therapeutic induction, accounting for 53.34% (654/1 226). For stillbirth during 28-37 weeks, pre-eclampsia was the major cause, accounting for 40.67% (255/627). And for full-term stillbirth, the causes were umbilical cord factors (19.37%, 68/351), abnormal labor (17.09%, 60/351). (3) In all the stillbirth cases, the incidence of fetal growth restriction (FGR) <28 weeks was significantly higher than that during 28-37 weeks [23.49% (288/1 226) vs 18.02% (113/627) , P<0.01]. (4) The stillbirth rate during labor was significantly higher in women ≥35 years old than in younger women [63.88% (191/299) vs 36.12% (108/299) ; χ(2)=9.346, P=0.000]. For the causes of stillbirth during labor, the incidence of severe maternal obstetrical complications [61.11% (33/54) vs 38.89% (21/54) ; χ(2)=3.323, P=0.002], abnormal labor [65.82% (52/79) vs 34.18% (27/79) ; χ(2)=4.067, P=0.001] and abnormal fetal position [66.63% (26/39) vs 33.37% (13/39) ; χ(2)=3.002, P=0.013] were higher in women ≥35 years old than in younger women. (5) Cesarean section during labor accounted for 33.77% (101/299) of stillbirth, including 76 cases of emergency cesarean section or converted to cesarean section during labor. Conclusions: (1) The incidence of stillbirth in the 11 hospitals is high, and the causes are different at different gestational ages, therefore, different interventions are needed to reduce the incidence in different gestational weeks. Supervision of therapeutic induction should be strengthened <28 gestational weeks; standard management of pregnancy might decrease the occurrence of natural death ≥28 weeks. (2) Attention should be paid to fetal body weight during pregnancy, especially FGR. (3) The stillbirth rate is high in elderly pregnant women, so it is important to strengthen the management of the elderly pregnant women.

Genetic variation in the MITF promoter affects skin colour and transcriptional activity in black-boned chickens

1. Microphthalmia-associated transcription factor (MITF) plays a pivotal role in melanocyte development by regulating the transcription of major pigmentation enzymes (e.g. TYR, TYRP1 and DCT). A single-nucleotide polymorphism (SNP), c.-638T>C, was identified in the MITF promoter, and genotyping of a population (n = 426) revealed that SNP c.-638T>C was associated with skin colour in black-boned chickens. 2. Individuals with genotypes CC and TC exhibited greater MTIF expression than those with genotype TT. Luciferase assays also revealed that genotype CC and TC promoters had higher activity levels than genotype TT. Expression of melanogenesis-related gene (TYR) was higher in the skin of chickens with the CC and CT genotype compared to TT chickens (P < 0.05). 3. Transcription factor-binding site analyses showed that the c.-638C allele contains a putative binding site for transcription factor sterol regulatory element-binding transcription factor 2, aryl hydrocarbon receptor nuclear translocator, transcription factor binding to IGHM enhancer 3 and upstream transcription factor 2. In contrast, the c.-638T allele contains binding sites for Sp3 transcription factor and Krüppel-like factor 1. 4. It was concluded that MITF promoter polymorphisms affected chicken skin colour. SNP c.-638T>C could be used for the marker-assisted selection of skin colour in black-boned chicken breeding.

The differentiation of beige adipocyte in pericardial and epicardial adipose tissues induces atrial fibrillation development

OBJECTIVE

Growing evidence has identified that excessive accumulation of pericardial adipose tissues (PAT) and epicardial adipose tissues (EAT) is associated with atrial fibrillation (AF) development. Moreover, beige adipocytes, present in PAT and EAT, have been proved beneficial in consumption of fatty acid and promotion of weight lose by nonshivering thermogenesis. The objective of this prospective, observational study was to reveal the potential association between beige adipocytes and AF development.

PATIENTS AND METHODS

Fat tissues from subcutaneous adipose tissue (SAT), PAT and EAT were obtained from 70 AF and 30 sinus rhythm patients. Hematoxylin and eosin (H&E) staining were performed to analyze morphological changes in fat tissues. Real-time PCR was performed to identify mRNA expression of unique uncoupling protein-1 (UCP-1). Western blotting and immunohistochemistry (IHC) were performed to determine protein expression of UCP-1.

RESULTS

Our results indicated that pericardial and epicardial adipocytes in AF patients demonstrated white-like change tendency and had lower expression of UCP-1 when compared to sinus rhythm patients. Additionally, the decrease of UCP-1 mRNA expression in PAT and EAT, together with LA enlargement, were independent risk factors of AF. Further, UCP-1 mRNA expression in EAT, but not in PAT, have a significant correlation with LA diameter. The function of nonshivering thermogenesis in PAT and EAT was impaired in AF patients, and this dysfunction in EAT had a great correlation with LA dilation.

CONCLUSIONS

Our data provide a new therapeutic target for LA remodeling and AF treatment.

α2-adrenoceptor-mediated inhibition in the central amygdala blocks fear-conditioning

The central amygdala is critical for the acquisition and expression of fear memories. This region receives a dense innervation from brainstem noradrenergic cell groups and has a high level of α₂-adrenoceptor expression. Using whole-cell electrophysiological recordings from rat brain slices, we characterise the role of pre-synaptic α₂-adrenoceptor in modulating discrete inhibitory and excitatory connections within both the lateral and medial division of the central amygdala. The selective α₂-adrenoceptor agonist clonidine blocked the excitatory input from the pontine parabrachial neurons onto neurons of the lateral central amygdala. In addition, clonidine blocked inhibitory connections from the medial paracapsular intercalated cell mass onto both lateral and medial central amygdala neurons. To examine the behavioural consequence of α₂-adrenoceptor-mediated inhibition of these inputs, we infused clonidine into the central amygdala prior to contextual fear-conditioning. In contrast to vehicle-infused rats, clonidine-infused animals displayed reduced levels of freezing 24 hours after training, despite showing no difference in freezing during the training session. These results reveal a role for α₂-adrenoceptors within the central amygdala in the modulation of synaptic transmission and the formation of fear-memories. In addition, they provide further evidence for a role of the central amygdala in fear-memory formation.

[Acute toxicity and bio-distribution of silver nitrate and nano-silver with different particle diameters in rats]

Objective: To explore the acute toxic effect and the cumulative target organ of silver nitrate and nano-silver with two different particle diameters in rats. Methods: Thirty-six adult SD rats were divided into small particle size nano-silver group (SNS), large particle size nano-silver group (LNS), silver nitrate group (SN), and control group (C) according to the random number table, with 9 rats in each group. The rats of the four groups were respectively injected with 10 mg/mL nano-silver solution (particle diameter of 20 nm, prepared by saline) in silver dose of 30 mg/kg by tail vein for once, 10 mg/mL nano-silver solution (particle diameter of 100 nm, prepared by saline) in silver dose of 30 mg/kg, 1.67 mg/mL silver nitrate solution (prepared by glucose solution) in silver dose of 3 mg/kg, and 30 mg/mL polyvinylpyrrolidone solution (prepared by saline) in dose of 90 mg/kg. (1) Toxicity test. The general observation was performed within 14 days after injection, and the deviation between value of body mass before injection and each of that on post injection day (PID) 1, 7, and 14 were respectively recorded. On PID 1, 7, and 14, 3 rats of each group were harvested for determination of serum content of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total protein, and albumin by fully automatic biochemical analyzer. Then the rats were sacrificed immediately, and heart tissue, liver tissue, spleen tissue, lung tissue, kidney tissue, and brain tissue were collected to calculate the organ coefficient. Organ samples with obvious changes in organ coefficient were collected for histopathological observation by HE staining, with 3 samples in each group at each time point. (2) Bio-distribution. The specimens of heart, liver, spleen, lung, and kidney of rats from groups SNS, LNS, and SN were collected for detection of silver content by inductively coupled plasma mass spectrometry, with 3 samples in each group at each time point. Data were processed with analysis of variance of factorial design, LSD test, and Dunnett's T3 test. Results: (1) The general condition of rats in groups C and SN after injection were normal. The state of rats of groups SNS and LNS was poor with black secretion in the eye and other phenomena on PID 1, which recovered from PID 3 on. (2) The deviations between values of body mass before injection and that on PID 14 in rats of groups LNS and SN were significantly decreased as compared with deviation of group C (with P values below 0.01), but deviation of group SNS was not significantly changed (P>0.05). The deviations between values of body mass before injection and each of that on PID 1 and 7 in rats in the other three groups were similar to those in group C (with P values above 0.05). (3) Compared with those in group C, the serum content of total protein of rats in group SN on PID 1 was significantly decreased, and liver coefficient was significantly increased (with P values below 0.05). On PID 1, the serum content of ALT of rats in group LNS was (61.0±8.7) U/L, which was significantly higher than that in group C [(40.0±4.6) U/L, P<0.01]. Compared with those in group C [(126.0±3.5) U/L and 4.05±0.23], the serum content of AST of rats in groups SNS and LNS on PID 1[(249.7±107.2) and (237.0±38.3) U/L] was significantly increased, and liver coefficients (3.50±0.38 and 3.31±0.07) were significantly decreased, with P values below 0.05. Compared with those in group C [(69.2±4.8) U/L and 4.32±0.39], the serum content of AST of rats in groups SNS and LNS on PID 7 [(181.0±51.5) and (167.7±16.5) U/L] was also significantly increased, and liver coefficients (3.55±0.18 and 3.62±0.21) were also significantly decreased, P<0.05 or P<0.01. On PID 14, the four liver biochemical indexes in serum and all organ coefficients of rats in the other three groups were similar to those in group C (with P values above 0.05). (4) The liver of rats in group SN had slight degeneration on PID 1, the liver cells around the central vein of liver of rats in group SNS had slight degeneration on PID 7, and the liver cells got severely eosinophilic degeneration in liver of rats in group LNS on PID 7. There was no significant pathological change in the liver of rats in each group at the rest time points. (5) The silver content of lung and kidney in rats of group SNS on PID 1, that of spleen and kidney in rats of group LNS on PID 1, and that of heart and kidney in rats of groups LNS and SNS on PID 7 was significantly less than that of group SN (with P values below 0.05). The silver content of liver and spleen in rats of group SNS on PID 14 was significantly more than that of group SN (with P values below 0.05). Compared with that of group SN, the silver content of lung on PID 1 and liver on PID 7 in rats of group LNS was significantly increased (with P values below 0.05). On PID 14, there was no significant change in the silver content of all organs of rats between group SN and group LNS (with P values above 0.05). The silver content of heart, lung, and kidney on PID 1 and heart on PID 7 in rats of group LNS was significantly more than that of group SNS (with P values below 0.05). On PID 14, the silver content of each organ of rats in group SNS was close to that in group LNS (with P values above 0.05). Conclusions: Silver nitrate and nano-silver with two different particle diameters have a short acute toxic effect on the liver of rats, and the liver has certain ability of self-healing. Nano-silver is mainly accumulated in the liver. The distribution of nano-silver with large particle diameter in organs is more widely than that of nano-silver with small particle diameter.

Polarization-dependent effects of an Airy beam due to the spin-orbit coupling

We investigate the polarization-dependent effects when a circularly polarized Airy beam propagates in an inhomogeneous medium. It shows that there are some interesting polarization-dependent phenomena induced by the spin-orbit coupling: the circularly polarized Airy beam will follow a polarization-dependent trajectory in an inhomogeneous medium, and there are the polarization-dependent self-acceleration of the Airy beam in the linear-index inhomogeneous medium and the polarization-dependent rotation of the Airy beam in the quadratic-index inhomogeneous medium. These polarization-dependent phenomena are different from the manifestation of the "traditional" spin Hall effect of a light beam, which just displays the polarization-dependent transverse deflection of the beam.

Enhanced THz Smith-Purcell radiation based on the grating grooves with holes array

Smith-Purcell radiation is emitted when an electron passes above the surface of a metallic grating. Its mechanism can be explained with Huygens' principle by the radiation of a moving oscillating dipole, which is formed by the moving charge and its image in the metallic grating. Here, an alternative way is presented to enhance the THz Smith-Purcell radiation. By drilling a hole in the fins of a grating as an effective electron channel, the oscillation dipole happens in two dimensions here, instead of one dimension. As a result, the Smith-Purcell radiation power is ten times more than the case in which the electron passes very close to the grating surface. This method is expected to improve the efficiency of the devices which are based on the Smith-Purcell radiation.