Dynamic-Shift Single- and Double-Negative Refractive Index in a Novel Three-Dimensional Metamaterial

A novel three-dimensional terahertz metamaterial by integrating planar and standup resonators on a sapphire substrate is proposed. This structure shows the capability of dynamic-shifting single- and double-negative refractive index bands under temperature control. When the temperature rises from 160 K to 290 K, the single- and double-negative bands of the metamaterials exhibit blue-shift, which is attributed by the simultaneously tuning of the electromagnetic resonance frequencies of the resonators. If the temperature rises to 300 K, the bianisotropy of the metamaterials increases rapidly, while it performs stable between 160 K and 290 K.

     

Thymic stroma-derived T cell growth factor (TSTGF). IV. Capacity of TSTGF to promote the growth of L3T4- Lyt-2- thymocytes by synergy with phorbol myristate acetate or various IL

The present study investigates the role of thymic stroma-derived T cell growth factor (TSTGF) in promoting the growth of L3T4- Lyt2- (double-negative) thymocytes. Partially purified TSTGF samples were prepared from the culture supernatant of a newly established thymic stromal cell line, MRL104.8a. The TSTGF alone induced only marginal proliferation of double-negative thymocytes, whereas this factor exerted a potent growth-promoting effect on these cells in combination with PMA. Because such an enhanced proliferation was not inhibited by anti-IL-4 or anti-IL-2R antibody, this was not due to the stimulation of an autocrine mechanism involving the production and utilization of IL-4 or IL-2. In scrutinizing PMA-equivalent physiologic substance(s), IL-1 was revealed to be capable of replacing the role of PMA in the above co-stimulation cultures and including enhanced proliferation of double-negative thymocytes in combination with TSTGF. Although TSTGF plus IL-2 or IL-4 also exhibited an appreciable or moderate synergistic effect on the growth of double-negative thymocytes, its magnitude was weaker compared with that obtained by TSTGF plus IL-1. More important, the strikingly enhanced proliferation was induced in the combinations of TSTGF, IL-1, and IL-2 or IL-4 under conditions in which the proliferation induced by IL-1 plus IL-4 or IL-1 plus IL-2 was marginal or slight. Furthermore, such strongly enhanced proliferation was also observed in the double-negative thymocyte population which was additionally depleted of T3+ cells (namely, the L3T4- Lyt-2- T3- or dull population). These results indicate the crucial role of TSTGF in the proliferation of immature thymocytes by synergy with various cytokines.     

Expression of the J11d marker on peripheral T lymphocytes of MRL-lpr/lpr mice

MRL-lpr/lpr (lpr) mice spontaneously develop massive lymphadenopathy resulting from the expansion of a unique population of Thy-1+ cells which are CD4- and CD8- (double negative) and the nature of which is not clear. The antibody J11d has been shown to define a differentiation Ag found on immature thymocytes but not on mature and functional peripheral CD4+ or CD8+ T cells. To analyze the possible relationship between the lpr double-negative T cells and the thymocytes, we investigated the simultaneous expression of J11d and Thy 1 Ag on the double-negative lpr lymph node cells by using two-color immunofluorescent staining technique. We observed that lpr mice at 3 to 4 weeks of age, before the onset of lymphadenopathy, did not have significant numbers (less than 4%) of J11d+ T cells in the periphery, similar to the number found in the control MRL +/+ mice. However, with increasing age of approximately 8 to 10 weeks and coinciding with the appearance of lymphadenopathy, a significant number (approximately 35%) of J11d+ Thy-1+ cells started appearing in the periphery of lpr mice and was maintained until the mice died at 20 to 24 weeks of age. The J11d+ T cells belonged to the abnormal double-negative T cell pool, inasmuch as J11d+ CD4+ or J11d+ CD8+ cells were absent in the lymph nodes of 20-wk-old lpr mice. Furthermore, 20-wk-old lpr mice demonstrated increased numbers (approximately 41%) of double-negative T cells in the thymus, a significant proportion of which were J11d+. In contrast, the 20-wk-old +/+ mice or 4-wk-old lpr mice had only 4% double-negative T cells in the thymus. The present study suggests that a significant number of peripheral double-negative T cells of lpr mice bear the immature thymic differentiation Ag J11d. The possibility that the accumulation of double-negative T cells results from abnormal peripheralization of double-negative J11d+ thymocytes, before complete differentiation into CD4+ or CD8+ T cells, is discussed.     

Structure-activity relationship of flavonoids as influenza virus neuraminidase inhibitors and their in vitro anti-viral activities

Flavonoids are polyphenolic compounds that widely exist in plant kingdom, and the structure-activity relationship (SAR) of 25 flavonoids was studied on neuraminidase (NA) activity of influenza virus. Three typical influenza virus strains A/PR/8/34 (H1N1), A/Jinan/15/90 (H3N2), and B/Jiangshu/10/2003 were used as the source of NAs, the average of IC(50)s of these compounds on these NAs was used in the SAR analysis. The order of potency for NA inhibition was as follows: aurones>flavon(ol)es>isoflavones>flavanon(ol)es and flavan(ol)es. The SAR analysis of flavonoids on influenza virus NAs revealed that for good inhibitory effect, the 4'-OH, 7-OH, C4O, and C2C3 functionalities were essential, and the presence of a glycosylation group greatly reduced NA inhibition. The in vitro anti-viral activities of eight flavonoids were evaluated using a cytopathic effect (CPE) reduction method, the assay results confirmed the SAR as influenza virus neuraminidase inhibitors. The findings of this study provide important information for the exploitation and utilization of flavonoids as NA inhibitors for influenza treatment.     

模拟酸雨对鼎湖山季风常绿阔叶林土壤呼吸的初期影响

通过在鼎湖山季风常绿阔叶林(季风林)进行野外模拟酸雨试验,对不同酸雨强度处理下的林地土壤呼吸速率进行原位测定,探讨酸雨对南亚热带森林土壤呼吸的初期影响。结果表明:在两年的测定周期内,4个酸雨水平:CK(pH值4.5左右的天然湖水)、T1(pH值4.0)、T2(pH值3.5)和T3(pH值3.0)处理下的年平均土壤呼吸速率分别为(3.07±0.08)、(3.06±0.17)、(2.78±0.29)和(2.56±0.08)μmol·m~(-2)·s~(-1),其中T3处理显著低于CK和T1处理(P0.05),说明模拟酸雨抑制了季风林土壤呼吸。这种抑制作用大体上随处理时间的延长而逐渐显著,处理间的差异只在测定周期的第二年达到显著水平,且抑制作用的差异显著性只出现在湿季(P0.05)。模拟酸雨对土壤呼吸的抑制作用可能与其胁迫下土壤酸化而导致土壤微生物异养呼吸及凋落物CO_2释放量下降有关。表现为模拟酸雨导致土壤pH值降低,使得土壤酸化加剧;降低了土壤微生物量碳、氮含量,抑制了微生物活性;提高了凋落物质量残留率,抑制了凋落物分解。还与土壤呼吸结果相对应,上述指标对模拟酸雨的响应也大体上随处理时间的延长而逐渐显著。另外,土壤呼吸温度敏感系数Q_(10)值随处理pH值降低有下降的趋势,表明酸雨处理在一定程度上降低了土壤呼吸的温度敏感性。     

Systemic Acquired Resistance to Virus Infections and Ethylene Biosynthesis in Asparagus Bean

Systemic acquired resistance (SAR) was induced in asparagus bean following inoculation with tobacco necrosis virus (TNV) or tobacco rattle virus (TRV), viruses that produce a hypersensitive reaction in this plant. SAR was expressed against challenge by TNV as reduction in lesion size, but not as inhibition of viral antigen accumulation. Systemic stimulation of ethylene-forming enzyme (EFA) activity, in the absence of any ethylene increase or 1-aminocyclopropane-1-carboxylic acid (ACC) accumulation, was associated with SAR. Formation of local necrotic lesions was necessary for both induction of SAR and stimulation of EFA, because early removal of inducer leaves prevented both events. SAR was expressed at rather constant level between 7 and 12 days after inducing infection. EFA stimulation declined with time and was no longer detected 7 days after inducing infection. SAR was not expressed against cucumber mosaic virus, that infect asparagus bean systemically. Prior inoculation with TNV or TRV was ineffective to reduce CMV antigen content or to minimize the pathogenic effect of this virus in systemically infected leaves.     

Characterization of reciprocal Lmb1-4 interval MRL-Faslpr and C57BL/6-Faslpr congenic mice reveals significant effects from Lmb3

Susceptibility to severe lupus in MRL-Fas(lpr) mice requires not only the lpr mutation but also other predisposing genes. Using (MRL-Fas(lpr) x B6-Fas(lpr))F2 (where B6 represents C57BL/6) intercrosses that utilize the highly susceptible MRL and poorly susceptible B6 backgrounds, we previously mapped CFA-enhanced systemic lupus-like autoimmunity to four loci, named Lmb1-4, on chromosomes 4, 5, 7, and 10. In the current study, we generated and analyzed reciprocal interval congenic mice for susceptibility to CFA-enhanced autoimmunity at all four Lmb loci. Although all loci had at least a slight effect on lymphoproliferation, only Lmb3 demonstrated a major effect on lymphoproliferation and anti-chromatin Ab levels. Further characterization of Lmb3, primarily by comparing MRL-Fas(lpr) with MRL.B6-Lmb3 Fas(lpr) congenic mice, revealed that it also played a significant role in spontaneous lupus, modifying lymphoproliferation, IgG and autoantibody levels, kidney disease, and survival. The less susceptible B6 Lmb3 locus was associated with a marked reduction in numbers of CD4(+) and double-negative (CD4(-)CD8(-)) T cells, particularly in lymph nodes, as well as reduced T cell proliferation and enhanced T cell apoptosis, both in vivo and in vitro. IFN-gamma-producing CD4(+) T cells were also reduced in MRL.B6-Lmb3 Fas(lpr) mice. Further mapping using subinterval congenic mice placed Lmb3 in the telomeric portion of chromosome 7. Thus, Lmb3, primarily through its effects on CD4(+) and double-negative T cells, appears to be a highly penetrant lupus-modifying locus. Identification of the underlying genetic alteration responsible for this quantitative trait locus should provide new insights into lupus-modifying genes.     

Density functional theory studies on the generation of trimethylenemethanes from the ring opening of dialkoxymethylenecyclopropanes and methylenecyclopropanethioacetals and follow-up reactions

This work reports a detailed DFT study on the generation of trimethylenemethanes (TMMs) from the ring opening of dialkoxymethylenecyclopropane (DMCP), methylenecyclopropanethioacetal (MCPT), and substituted derivatives of DMCP and MCPT, as well as follow-up reactions of the TMMs. The singlet DMCP and MCPT were found to be 51.32 and 53.77 kcal mol^?1 more stable than the triplet DMCP and MCPT respectively, corresponding to triplet:singlet population ratios of 1:10³⁸ and 1:10⁴⁰, respectively, at 25 °C using Boltzmann distribution, implying that the proportion of the triplet species is negligible at 25 °C. The ring-opening reactions occur through singlet transition states with barriers of 40.68 and 42.27 kcal mol^?1 for DMCP and MCPT, respectively, and yield TMMs that are very unstable compared to the precursors, with the triplet TMM being far more stable than the singlet. Whereas the singlet TMMs readily undergo cycloaddition reactions with olefins to form five-membered carbocyclic rings, the triplet species do not. The selectivity of the reactions of the DMCP TMMs is very sensitive to temperature; at 25°C, cycloaddition with olefins and ring-closure to form ketenes have very comparable barriers while temperatures above 150 °C favor the exclusive formation of a ketene followed by dimerization. In MCPT, ring closure to form ketenes is the favored reaction at all temperatures studied.

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Graphical abstract

Pathways for the generation of trimethylenemethanes from their precursors and follow-up reactions

     

Adhesion of Candida albicans mutant strains to host tissue

Adhesion of Candida albicans to host cells is believed to represent a fungal virulence factor and a significant step in the development of candidiasis. As C. albicans strains may differ in their in vitro adhesion ability we initiated a study to investigate whether mutant strains differ in this respect from their parent wild-type. We assessed the in vitro adhesion of C. albicans CBS562 and two mutants obtained by mutagenesis with N′-nitrosoguanidine: a histidine auxotroph, SAG5, derived from CBS562, and a respiratory-deficient strain (a petite mutant), SAR1, derived from SAG5. The adhesion was tested in vitro using two target cell systems: (1) exfoliated human buccal epithelial cells (BEC); and (2) human keratinocyte tissue line cells (HaCaT cells). Adhesion to BEC was evaluated microscopically and that to HaCaT cells by a direct ELISA technique. The results indicated a 54% reduction in adhesion to BEC for SAG5 and 30% for SAR1 as compared to the wild-type, and a 25% reduction in adhesion to HaCaT cells for SAG5 and 20% for SAR1. To verify whether the prototrophy restores the adhesion ability, we complemented the his-negative auxotroph by transforming the strain with the HIS4 gene. Then we assayed the adhesion to BEC of the complemented his-negative mutant in comparison to that of the wild-type, the his-negative mutant (SAG5) and the plasmid-cured transformant. The adhesion values of the complemented his-negative strain were similar to those of the wild-type, whereas the values of the plasmid-cured strain were similar to those of SAG5.     

Tagus estuary salt marshes feedback to sea level rise over a 40-year period: Insights from the application of geochemical indices

Sea level rise (SLR) has been evaluated using data acquired from two Tagus estuary salt marshes. Sediment accumulation rates over a 40-year study period were determined using ¹³⁷Cs along with an evaluation of several geochemical indices and ratios as proxies of the mechisms underlying these SAR variations. Correlating SLR data from 1963 to 2001 with the sediment accretion rates (SARs) an inverse pattern of interaction was observed, with lower SAR associated to periods of higher mean sea level (MSL) heights. This pointed out to an erosion effect of the salt marsh during higher tidal flooding. Although SLR apparently slows down SAR, it still presents a positive balance with SLR, similar to that identified in most mesotidal estuaries. The geochemical analysis of sediments and chemical alteration index (CAI) also suggest that the major processes inherent to the SAR vary inversely, being mostly based by physical disturbances. Geochemical ratio-based indices showed that both salt marshes presented enhanced high-energy transport driven inputs of sediments, although in Pancas salt marsh there is a slight evidence of chemical weathering of the sediments. Anthropogenic contamination of the sediments by heavy metals was identified and has been decreasing from 1963 to 2001, mostly linked to a marked reduction of industrial activities in some areas surrounding the Tagus estuary, rather than the sedimentary history of the estuary.     

Metallic electrodes and leads in simultaneous EEG-MRI: specific absorption rate (SAR) simulation studies

The purpose of this study was to investigate the changes in specific absorption rate (SAR) in human-head tissues while using nonmagnetic metallic electroencephalography (EEG) electrodes and leads during magnetic resonance imaging (MRI). A realistic, high resolution (1 mm(3)) head model from individual MRI data was adopted to describe accurately thin tissues, such as bone marrow and skin. The RF power dissipated in the human head was evaluated using the FDTD algorithm. Both surface and bird cage coils were used. The following numbers of EEG electrodes/leads were considered: 16, 31, 62, and 124. Simulations were performed at 128 and 300 MHz. The difference in SAR between the electrodes/leads and no-electrodes conditions was greater with the bird cage coil than with the surface coil. The peak 1 g averaged SAR values were highest at 124 electrodes, increasing to as much as two orders of magnitude (x172.3) at 300 MHz compared to the original value. At 300 MHz, there was a fourfold (x3.6) increase of SAR averaged over the bone marrow, and a sevenfold (x7.4) increase in the skin. At 128 MHz, there was a fivefold (x5.6) increase of whole head SAR. Head models were obtained from two different subjects, with an inter-subject whole head SAR variability of 3%. .     

Diversity and abundance of “Pelagibacterales” (SAR11) in the Baltic Sea salinity gradient

The candidate order “Pelagibacterales” (SAR11) is one of the most abundant bacterial orders in ocean surface waters and, periodically, in freshwater lakes. The presence of several stable phylogenetic lineages comprising “Pelagibacterales” correlates with the physico-chemical parameters in aquatic environments. A previous amplicon sequencing study covering the bacterial community in the salinity gradient of the Baltic Sea suggested that pelagibacteral subclade SAR11-I was replaced by SAR11-IIIa in the mesohaline region of the Baltic Sea. In this current study, we investigated the cellular abundances of “Pelagibacterales” subclades along the Baltic Sea salinity gradient using catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH). The results obtained with a newly designed probe, which exclusively detected SAR11-IIIa, were compared to CARD-FISH abundances of the marine SAR11-I/II subclade and the freshwater lineage SAR11-IIIb (LD12). The results showed that SAR11-IIIa was abundant in oligohaline–mesohaline conditions (salinities 2.7–13.3), with maximal abundances at a salinity of 7 (up to 35% of total Bacteria, quantified with a universal bacterial probe EUB). As expected, SAR11-I/II was abundant (27% of EUB) in the marine parts of the Baltic Sea, whereas counts of the freshwater lineage SAR11-IIIb were below the detection limit at all stations. The shift from SAR11-IIIa to SAR11-I/II was confirmed in the vertical salinity gradient in the deeper basins of the Baltic Sea. These findings were consistent with an overlapping but defined distribution of SAR11-I/II and SAR11-IIIa in the salinity gradient of the Baltic Sea and suggested the adaptation of SAR11-IIIa for growth and survival in mesohaline conditions.     

Metabolic strategies of free-living and aggregate-associated bacterial communities inferred from biologic and chemical profiles in the Black Sea suboxic zone

The Black Sea is a permanently anoxic basin with a well-defined redox gradient. We combine environmental 16S rRNA gene data from clone libraries, terminal restriction fragment length polymorphisms, and V6 hypervariable region pyrosequences to provide the most detailed bacterial survey to date. Furthermore, this data set is informed by comprehensive geochemical data; using this combination of information, we put forward testable hypotheses regarding possible metabolisms of uncultured bacteria from the Black Sea's suboxic zone (microaerophily, nitrate reduction, manganese cycling, and oxidation of methane, ammonium, and sulfide). Dominant bacteria in the upper suboxic zone included members of the SAR11, SAR324, and Microthrix groups and in the deep suboxic zone included members of BS-GSO-2, Marine Group A, and SUP05. A particulate fraction (30?μm filter) was used to distinguish between free-living and aggregate-attached communities in the suboxic zone. The particulate fraction contained greater diversity of V6 tag sequences than the bulk water samples. Lentisphaera, Epsilonproteobacteria, WS3, Planctomycetes, and Deltaproteobacteria were enriched in the particulate fraction, whereas SAR11 relatives dominated the free-living fraction. On the basis of the bacterial assemblages and simple modeling, we find that in suboxic waters, the interior of sinking aggregates potentially support manganese reduction, sulfate reduction, and sulfur oxidation.     

Distribution of cellular isoform of prion protein in T lymphocytes and bone marrow, analyzed by wild-type and prion protein gene-deficient mice

In this study, the authors investigated normal cellular prion protein (PrP(C)) expression on murine immune systems using prion protein gene-deficient mouse as negative control. Immunocytes expressing PrP(C) in adult and fetal mice were detected by flow cytometry with the monoclonal antibody against PrP(C), 6H4. Cells from thymus and bone marrow reacted positively with 6H4, while spleen cells, peritoneal cells, peripheral blood leukocytes, and intestinal intraepithelial lymphocytes were nonreactive. In thymus, PrP(C) was observed in CD4(-)CD8(-) double-negative thymocytes. PrP(C+) cells of double-negative thymocytes belonged to the CD3(-) subset, but not to the CD3(+) subset. Triple-negative PrP(C+) thymocytes expressed CD44 or CD25 antigens. Furthermore, PrP(C) was observed in c-kit(+) bone marrow cells. In fetuses, PrP(C+) cells were observed in the liver and thymus at day 16.0 and 15.0 of gestation, respectively. These results demonstrated that PrP(C) is expressed on immature immunocytes.     

Induction of an adaptive response in human blood lymphocytes exposed to radiofrequency fields: influence of the universal mobile telecommunication system (UMTS) signal and the specific absorption rate

The induction of an adaptive response (AR) was examined in human peripheral blood lymphocytes exposed to non-ionizing radiofrequency fields (RF). Cells from nine healthy human volunteers were stimulated for 24h with phytohaemagglutinin and then exposed for 20h to an adaptive dose (AD) of a 1950MHz RF UMTS (universal mobile telecommunication system) signal used for mobile communications, at different specific absorption rates (SAR) of 1.25, 0.6, 0.3, and 0.15W/kg. This was followed by treatment of the cells at 48h with a challenge dose (CD) of 100ng/ml mitomycin C (MMC). Lymphocytes were collected at the end of the 72h total culture period. The cytokinesis-block method was used to record the frequency of micronuclei (MN) as genotoxicity end-point. When lymphocytes from six donors were pre-exposed to RF at 0.3W/kg SAR and then treated with MMC, these cells showed a significant reduction in the frequency of MN, compared with the cells treated with MMC alone; this result is indicative of induction of AR. The results from our earlier study indicated that lymphocytes that were stimulated for 24h, exposed for 20h to a 900MHz RF GSM (global system for mobile communication) signal at 1.25W/kg SAR and then treated with 100ng/ml MMC, also exhibited AR. These overall data suggest that the induction of AR depends on RF frequency, type of the signal and SAR. Further characterization of RF-induced AR is in progress.     

Metamaterial-Embedded Low SAR PIFA for Cellular Phone

A metamaterial-embedded planar inverted-F antenna (PIFA) is proposed in this study for cellular phone applications. A dual-band PIFA is designed to operate both GSM 900 MHz and DCS 1800 MHz. The ground plane of a conventional PIFA is modified using a planar one-dimensional metamaterial array. The investigation is performed using the Finite Integration Technique (FIT) of CST Microwave Studio. The performance of the developed antenna was measured in an anechoic chamber. The specific absorption rate (SAR) values are calculated considering two different holding positions: cheek and tilt. The SAR values are measured using COMOSAR measurement system. Good agreement is observed between the simulated and measured data. The results indicate that the proposed metamaterial-embedded antenna produces significantly lower SAR in the human head compared to the conventional PIFA. Moreover, the modified antenna substrate leads to slight improvement of the antenna performances.     

Spike activity in pulmonary slow-adapting receptors during forced breathing

Spike activity pattern of 34 slow-adapting pulmonary receptors (SAR) was investigated in anesthetized cats during relaxed respiration and forced inhalation of CO₂. It was found that approximately one half of the SAR investigated did not differ substantially from relaxed breathing and showed regular intensification in relation to lung stretch. The frequency-volume plot underwent a shift to the right (or else a steeper rise in frequency during inspiration) under these conditions in most of the other receptors. All test SAR showed a reduction in firing rate during exhalation. The pattern of frequency-volume relationship at lung volumes not exceeding respiratory volume was not disrupted. A reduction in firing rate occurred with respiration in all the SAR investigated. The summated spike train from SAR, characterized by averaged frequency of the latter's spike activity, showed a linear dependence on lung volume during both forced and relaxed respiration alike but frequency rose more sharply in the former. Reasons for the changed activity of test SAR during forced breathing are discussed together with possible consequences of these changes for reflex regulation of time phases during the respiratory cycle.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 21, No. 5, pp. 629–636, September–October, 1989.     

The effects of RF absorbers on exposure levels at 100 MHz

The study presented in this article was designed to complete a dosimetry protocol required to establish the RF exposure levels at 100 MHz for measurement of the effect on cognition in human volunteers near the resonant frequency in seated positions. The results are compared with those reported previously using the same experimental procedures, except with the vertically radiating dipole antenna and corner reflector raised by .30 m to the vertical center of the anechoic chamber. The average whole body SAR for the high and low SAR conditions used in the previous study was achieved with a 12% increase in transmitter forward power. However, the incident power density averaged over the body was increased by 42%, from 40 and 80 W/m(2) in the previous study to 57 and 113 W/m(2) in the current study to achieve the same whole body average SAR used in the previous study. The differences in field patterns and field intensities between the previous and current studies were introduced by interactions between the E-field and RF absorbers in the floor and ceiling, which represent resonant structures at 100 MHz.     

Manipulating Magnetoinductive Coupling with Graphene-Based Plasmonic Metamaterials in THz Region

Coupling between physical modes can trigger some new physical phenomena such as frequency shift, new mode, and Rabi splitting. Resonant modes in graphene-based metamaterials provide a new platform for the research of coupling. In this work, we demonstrate that the plasmonic coupling of split ring resonator (SRR) dimer in graphene-based metamaterials can be easily manipulated. This magnetoinductive coupling can switch on/off the dark modes easily, which is usually done by symmetry-breaking structure previously. Furthermore, the dark mode can also be activated by Fermi energy as well as carrier concentration changing with either physical or chemical methods conveniently. In addition, different graphene-based SRR dimer configurations present different coupling strengths, which benefits the designing and optimizing of graphene-based metamaterials. The demonstration could enhance the versatility of both coupling studies in terahertz (THz) region and graphene-based metamaterials for THz devices.