On-Surface Fabrication toward Polar 2D Macromolecular Crystals

Polar 2D macromolecular structures have attracted significant attention because of their ferroelectricity and ferro-magnetism. However, it is challenging to synthesize them experimentally because dipoles or spins of these macromolecules tend to cancel each other. So far, there has been no successful strategy for assembling macromolecules in a unidirectional manner, achieving stereoregular polymerization on metal surfaces, and creating polar 2D polymer crystals. Recent progress in molecular assembly, on-surface polymer synthesis, and direct control of molecules using electric field applications provides an opportunity to develop such strategies. In this regard, we first review past studies on chiral and achiral molecular assembly, on-surface polymer synthesis, and orientation control of polar molecules. Then, we discuss our newly developed approach called "vectorial on-surface synthesis", which is based on "dynamic chirality" of compass precursors, stereoselective polymerization, and favorable interchain interactions originating from CH-π interactions. Finally, we conclude with a prospective outlook.

Deceptive orbital confinement at edges and pores of carbon-based 1D and 2D nanoarchitectures

The electronic structure defines the properties of graphene-based nanomaterials. Scanning tunneling microscopy/spectroscopy (STM/STS) experiments on graphene nanoribbons (GNRs), nanographenes, and nanoporous graphene (NPG) often determine an apparent electronic orbital confinement into the edges and nanopores, leading to dubious interpretations such as image potential states or super-atom molecular orbitals. We show that these measurements are subject to a wave function decay into the vacuum that masks the undisturbed electronic orbital shape. We use Au(111)-supported semiconducting gulf-type GNRs and NPGs as model systems fostering frontier orbitals that appear confined along the edges and nanopores in STS measurements. DFT calculations confirm that these states originate from valence and conduction bands. The deceptive electronic orbital confinement observed is caused by a loss of Fourier components, corresponding to states of high momentum. This effect can be generalized to other 1D and 2D carbon-based nanoarchitectures and is important for their use in catalysis and sensing applications.

Manifold dynamic non-covalent interactions for steering molecular assembly and cyclization

Deciphering rich non-covalent interactions that govern many chemical and biological processes is crucial for the design of drugs and controlling molecular assemblies and their chemical transformations. However, real-space characterization of these weak interactions in complex molecular architectures at the single bond level has been a longstanding challenge. Here, we employed bond-resolved scanning probe microscopy combined with an exhaustive structural search algorithm and quantum chemistry calculations to elucidate multiple non-covalent interactions that control the cohesive molecular clustering of well-designed precursor molecules and their chemical reactions. The presence of two flexible bromo-triphenyl moieties in the precursor leads to the assembly of distinct non-planar dimer and trimer clusters by manifold non-covalent interactions, including hydrogen bonding, halogen bonding, C-H⋯π and lone pair⋯π interactions. The dynamic nature of weak interactions allows for transforming dimers into energetically more favourable trimers as molecular density increases. The formation of trimers also facilitates thermally-triggered intermolecular Ullmann coupling reactions, while the disassembly of dimers favours intramolecular cyclization, as evidenced by bond-resolved imaging of metalorganic intermediates and final products. The richness of manifold non-covalent interactions offers unprecedented opportunities for controlling the assembly of complex molecular architectures and steering on-surface synthesis of quantum nanostructures.

Achievements and challenges of the Sakigake designation system in Japan

The Sakigake designation system (Sakigake) has been launched to encourage the pioneered development of innovative new medical products for the effective treatment of severe illness in Japan, which allows leveraging the several advantages in prioritized consultation, rapid review, premium drug pricing and extended data-protection period. We retrospectively analysed the Sakigake products including drugs and regenerative medical products to clarify the achievements and the future issues in this system. From April 2015 to August 2020 (the first 5-year trial period of Sakigake), 37 products were designated, and 10 of those were approved in Japan in which 7 new active substances achieved the first-in-world approvals. Oncology, neurology and cardiovascular disease were the major therapeutic areas, and those 3 accounted for 75.7% of all products. Sakigake achieved some first-in-world approvals by the Pharmaceuticals and Medical Devices Agency/the Ministry of Health, Labor and Welfare of innovative new medical products, although in some therapeutic areas, there remains room in stimulating drug development.

Rationales of delay and difference in regulatory review by Japan, the USA and Europe among new drugs first approved in Japan

AIMS

To clarify the rationales of delay or difference in the review of new drug applications among regulatory authorities for new drugs, those first approved in the world being in Japan.

METHODS

Among 80 new drugs first approved in Japan from 2008 to 2019, we identified those subsequently approved in the USA or Europe. Significant delays in approval time (boxplot outliers) and the rationales for the delays were assessed among the Pharmaceuticals and Medical Devices Agency (PMDA), the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA).

RESULTS

Of the 80 Japan-first approvals, 25 and 24 were approved in the USA and Europe, respectively, and their median approval times in Japan, the USA and Europe were 285, 334 and 477 days, respectively. Significant delays were identified for pirfenidone (1806 days, FDA), alogliptin benzoate (1856 days, FDA), insulin degludec (1457 days, FDA) and romosozumab (750 days, PMDA; 994 days, FDA; 748 days, EMA). Due to concerns about cardiovascular risk, alogliptin benzoate and insulin degludec were requested for additional clinical trials by the FDA, and romosozumab required a much longer review period than the standard approval time in all three regions.

CONCLUSIONS

Among the new drugs significantly delayed in approval time in Japan, the USA or Europe, there were some differences in the requirements, the participating regions and the assessment of clinical trials. The regulatory views on the cardiovascular risk also differed among the three regions. These divergences may be associated with the differences in approval histories.

Evolving Landscape of New Drug Approval in Japan and Lags from International Birth Dates: Retrospective Regulatory Analysis

The Pharmaceuticals and Medical Devices Agency (PMDA) has approved hundreds of new drugs in recent years. We retrospectively analyzed the new drugs approved in Japan from 2008 to 2019, and identify the first-in-world approvals and clarify the current drug lag. The new drug and the drug lag were defined as a drug with a new active substance and a difference between the approval date in Japan and the international birth date, respectively. Among 400 new drugs approved in Japan during the last 12 years, 80 (20.0%) were first approved in Japan, and 320 were outside Japan (the United States: 202, 50.5%; Europe: 82, 20.5%; other regions: 36, 9.0%). Of these, 45 new drugs have not yet been approved outside Japan, and the remaining 355 have been globally approved in Japan and overseas. The number of new drug approvals were the largest in oncology followed by metabolic/endocrine and infectious diseases. The median drug lags (year) among all 400 new drugs and 355 new drugs with global approvals were 4.3 and 4.7 in the first tertile (2008-2011), 1.5 and 2.6 in the second tertile (2012-2015), and reduced to 1.3 and 2.2 in the third tertile (2016-2019), respectively. Substantial drug lag remains in neurology, psychiatry, and therapeutic areas where the number of new drug approvals was relatively small. Collectively, one-fifth of the new drugs approved in Japan are first-in-world approvals. Drug lag has been greatly decreased, although it still exists.

Manipulable Metal Catalyst for Nanographene Synthesis

Performing bottom-up synthesis by using molecules adsorbed on a surface is an effective method to yield functional polycyclic aromatic hydrocarbons (PAHs) and nanocarbon materials. The intramolecular cyclodehydrogenation of hydrocarbons is a critical process in this synthesis; however, thus far, its elementary steps have not been elucidated thoroughly. In this study, we utilize the metal tip of a low-temperature noncontact atomic force microscope as a manipulable metal surface to locally activate dehydrogenation for PAH-forming cyclodehydrogenation. This method leads to the dissociation of a H atom of an intermediate to yield the cyclodehydrogenated product in a target-selective and reproducible manner. We demonstrate the metal-tip-catalyzed dehydrogenation for both benzenoid and nonbenzonoid PAHs, suggesting its universal applicability as a catalyst for nanographene synthesis.

Transarterial- chemoembolization remains an effective therapy for intermediate-stage hepatocellular carcinoma with preserved liver function

AIM

To evaluate outcomes as well as prognostic factors of transarterial chemoembolization (TACE) in intermediate-stage hepatocellular carcinoma (HCC) with preserved liver function to determine positioning of TACE.

METHODS

Of 158 treatment-naïve patients with intermediate-stage HCC who received initial TACE from February 2007 to January 2016, 113 patients met the following inclusion criteria: no combined therapy within 4 weeks after initial TACE, and Child-Pugh score under 7. Response rate and overall survival were evaluated. The prognostic factors were investigated in univariate and multivariate analyses using Cox proportional hazards models. The deterioration of liver function after repeated TACE was also evaluated.

RESULTS

The response rate was 92.7% (complete response, 63.3%; partial response, 29.4%). The median survival time was 45.2 months. Survival rates at 1, 2, and 3 years were 90.4%, 77.0%, and 60.8% respectively. Age ≥ 75 years (P = 0.022), serum α-fetoprotein level ≥ 200 ng/mL (P = .010), tumor number ≥ 11 (P = 0.008), and heterogeneous enhancement on dynamic computed tomography (P = 0.024) were poor prognostic factors. The deterioration rate of Child-Pugh score and albumin-bilirubin grade was 18.5% and 12.3%, respectively, after the first TACE, 15.6% and 5.1%, respectively, after the second TACE, and 14.5% and 11.1%, respectively, after the third TACE.

CONCLUSION

Superselective TACE can achieve high tumor response rates with prolonged overall survival for patients with intermediate-stage HCC with preserved liver function. Age, serum α-fetoprotein level, tumor number ≥ 11, and heterogeneous enhancement on dynamic computed tomography indicated significantly poor prognosis.

Role of Magnesium and the Effect of Surface Roughness on the Hydroxyapatite-Forming Ability of Zirconia Induced by Biomimetic Aqueous Solution Treatment

Zirconia is a well-known bioceramic for dental and orthopedic applications due to its mechanical and aesthetic properties. However, it lacks sufficient bioactivity to bond with the living bone. This study was aimed to induce bioactivity to tetragonal zirconia polycrystal (3Y-TZP) by simple biomimetic aqueous solution treatment. First, hydrofluoric acid (HF) etching was performed to enhance the surface roughness of the 3Y-TZP surface. Then, the samples were treated with two types of aqueous solutions containing calcium and phosphate ions (Ca-P solutions); one solution additionally contained magnesium (Mg) ions and the other without Mg ions. Finally, hydroxyapatite (HAp)-forming ability was evaluated by the conventional simulated body fluid (SBF) test, and the effect of Mg ions on the adhesive strength of the HAp layer to the roughened 3Y-TZP surface was also investigated. The results concluded that there were no noticeable differences in the effect of Mg ions on the HAp-forming ability, and both types of solution treatments resulted in dense HAp formation in 1 day SBF immersion. However, incorporation of Mg ions in one of the Ca-P solutions significantly improved the adhesive strength of the HAp layer to the HF-etched 3Y-TZP substrate compared to the Ca-P solution with no Mg ions.

Efficacy of combined bland embolization and chemoembolization for huge (≥10 cm) hepatocellular carcinoma

INTRODUCTION

To assess the efficacy of combined therapy involving bland transarterial embolization using gelatin sponge particles (bland GS-TAE) followed by transarterial chemoembolization using lipiodol mixed with anticancer agents and GS particles (Lip-TACE) to reduce the adverse events and increase the therapeutic effect of Lip-TACE in the treatment of huge (≥10 cm) hepatocellular carcinoma (HCC).

MATERIAL AND METHODS

Twenty-one consecutive patients with huge HCCs (≥10 cm in diameter) were enrolled in this study. First, bland GS-TAE was performed to reduce the tumor volume, and then Lip-TACE was performed to control the remaining tumor at intervals of around three weeks. Tumor response, survival, and adverse events of this combined therapy were assessed.

RESULTS

The tumor response was assessed three months after combined TACE, with complete response in 38.1% and partial response in 57.1% of cases. Severe adverse events were seen in two patients, acute cholecystitis and tumor rupture. The median survival time was 2.7 years, and the one-, two-, three-, and five-year overall survival rates were 76.2%, 66.7%, 42.9%, and 25.0%, respectively.

CONCLUSION

Combined therapy involving bland GS-TAE followed by Lip-TACE can be performed safety and may improve survival in patients with huge HCCs.

(Poly)terephthalates with Efficient Blue Emission in the Solid State

We prepared dimethyl and diaryl 2,5-dialkoxytere-phthalates from dimethyl 2,5-dihydroxyterephthalate in good-to-high yields via alkylation or a sequence of alkylation, hydrolysis, chlorination, and condensation. The absorption spectra of the dialkoxyterephthalates contain a small band at 332-355 nm, which could be assigned to intramolecular charge-transfer transition from the alkoxy to alkoxycarbonyl groups on the basis of theoretical calculations using density functional theory. The dialkoxyterephthalates exhibited blue fluorescence with moderate-to-excellent quantum yields not only in solution but also in the solid state, such as a poly(methyl methacrylate) (PMMA) film and a powder. The solid-state quantum yields of the diisopropoxy-substituted terephthalates were similar or considerably higher than those of the dimethoxy-substituted counterparts. Copolymerization of 2,5-diisopropoxyterephthaloyl chloride and 1,4-butanediol with or without terephthaloyl chloride gave brilliantly blue fluorescent polymers, whose quantum yields were 0.72 and 0.71 in toluene and 0.46 and 0.40 in the neat film, respectively. Furthermore, white emission was achieved when a fluorescent yellow 2,5-diaminoterephthalate was doped into the thin film of the blue fluorescent polymer at 0.4 wt %.

Dominance of Tensor Correlations in High-Momentum Nucleon Pairs Studied by (p,pd) Reaction

The isospin character of p-n pairs at large relative momentum has been observed for the first time in the ^{16}O ground state. A strong population of the J,T=1,0 state and a very weak population of the J,T=0,1 state were observed in the neutron pickup domain of ^{16}O(p,pd) at 392 MeV. This strong isospin dependence at large momentum transfer is not reproduced by the distorted-wave impulse approximation calculations with known spectroscopic amplitudes. The results indicate the presence of high-momentum protons and neutrons induced by the tensor interactions in the ground state of ^{16}O.

Development of Repeatable Microcatheter Access Port for Intra-arterial Therapy of Liver Cancer

PURPOSE

To develop an implantable port in which a microcatheter can be inserted for a combination therapy of repeated transarterial chemoembolization (TACE) and hepatic arterial infusion chemotherapy (HAIC) for advanced liver cancer.

MATERIALS AND METHODS

The design of a currently used implantable port was modified. A funnel part was constructed in the port. The septum was punctured by a 20-gauge indwelling needle, and 2.0-Fr non-tapered microcatheter was inserted into the port. In the in vitro studies, the advance of a microcatheter out of the funnel part was evaluated via seven different septum puncture sites. A 5-Fr indwelling catheter connected to the port was placed in a vascular model, and a microcatheter catheterization was evaluated. In an in vivo study, the port-catheter system was implanted in the hepatic artery in a pig. A microcatheter was percutaneously inserted through the port into the hepatic arterial branches, and embolization was performed.

RESULTS

In the in vitro studies, the microcatheter was smoothly advanced out of the port and catheterizations into the hepatic arteries were successful via all septum puncture sites. In the in vivo study, repeated selective embolization through the port was successfully conducted on 7, 14 and 21 days after the implantation.

CONCLUSION

The developed implantable port can be used for repeated catheter insertion into the hepatic artery. The combination of repeated TACE and HAIC could be possible using this device.

Electrostatic Repulsion-Induced Desorption of Dendritic Viologen-Arranged Molecules Anchored on a Gold Surface through a Gold-Thiolate Bond Leading to a Tunable Molecular Template

We investigated the adsorption and desorption behavior of self-assembled monolayers (SAMs) on gold derived from dendritic viologen-arranged molecules with an ω-mercaptodecyl group (A n, n (dendritic generation) = 0-3) at the apex of the dendritic structure in polar solvents. The adsorption of the dendritic molecules occurred quickly and saturated within a few minutes in an acetonitrile/ethanol (1/1, v/v) mixture at a concentration of 2 mM. Atomic force microscopy images of the SAMs showed flat surfaces regardless of the dendritic generation because the peripheral viologen units were closely packed at the surface of the molecular layer. Individual A3 molecules immobilized on the substrate were observed by scanning tunneling microscopy measurements of a mixed SAM with decanethiol. The desorption behaviors of dendritic molecules from the A n-SAMs in several solvents such as water were also investigated. The spontaneous desorption of the A n-SAM occurred more rapidly than that of a conventional n-alkanethiol SAM. However, the desorption was inhibited by adding electrolytes such as NaNO₃ due to the shielding effect on the electrostatic repulsion between the dendritic molecules. These results indicate that the surface density of the dendritic molecules can be controlled through the desorption.

Evidence for prevalent Z = 6 magic number in neutron-rich carbon isotopes

The nuclear shell structure, which originates in the nearly independent motion of nucleons in an average potential, provides an important guide for our understanding of nuclear structure and the underlying nuclear forces. Its most remarkable fingerprint is the existence of the so-called magic numbers of protons and neutrons associated with extra stability. Although the introduction of a phenomenological spin-orbit (SO) coupling force in 1949 helped in explaining the magic numbers, its origins are still open questions. Here, we present experimental evidence for the smallest SO-originated magic number (subshell closure) at the proton number six in 13-20C obtained from systematic analysis of point-proton distribution radii, electromagnetic transition rates and atomic masses of light nuclei. Performing ab initio calculations on 14,15C, we show that the observed proton distribution radii and subshell closure can be explained by the state-of-the-art nuclear theory with chiral nucleon-nucleon and three-nucleon forces, which are rooted in the quantum chromodynamics.

Wide graphene nanoribbons produced by interchain fusion of poly(p-phenylene) via two-zone chemical vapor deposition

Wide graphene nanoribbons (GNRs) were fabricated via two-zone chemical vapor deposition using 4,4''-dibromo-p-terphenyl as the precursor. Densely packed arrays of poly(p-phenylene) produced on Au(111) using this method could be converted into wide GNRs via interchain fusion by thermal annealing. The field-effect transistor prepared from these GNRs exhibited an excellent on/off current ratio of 1.6 ± 0.6 × 10³.

Effects of the ether oxygen atom in alkyl side chains on the physical properties of piperidinium ionic liquids

Various types of piperidinium ionic liquids equipped with an oxygen atom-containing alkyl side chain on the positively charged nitrogen atom were systematically synthesized and their physical properties investigated.

Orientation and Electronic Structures of Multilayered Graphene Nanoribbons Produced by Two-Zone Chemical Vapor Deposition

The orientation and electronic structure of multilayered graphene nanoribbons with an armchair-edge (AGNRs) were determined by low-temperature scanning tunneling microscopy in this study. The orientation of AGNRs was found to be an edge-on structure when positioned as a top layer, while previous reports showed a face-on structure for monolayered AGNRs on Au(111). According to density functional theory calculations, AGNRs in a top layer preferentially form as edge-on structures rather than face-on structures due to the balance of CH-π and π-π interactions between AGNRs. Scanning tunneling spectroscopy and density functional theory calculations revealed that the electronic structures of multilayered AGNRs are similar to those in a gas-phase due to the lack of interaction between AGNRs and the Au(111) substrate. The observation of AGNRs in mutilayers might suggest the conformation-assisted mechanism of dehydrogenation when there is no contact with the Au(111) substrate.

Efficacy of protocol-based pharmacotherapy management on anticoagulation with warfarin for patients with cardiovascular surgery

WHAT IS KNOWN AND OBJECTIVE

Anticoagulation therapy with warfarin requires periodic monitoring of prothrombin time-international normalized ratio (PT-INR) and adequate dose adjustments based on the data to minimize the risk of bleeding and thromboembolic events. In our hospital, we have developed protocol-based pharmaceutical care, which we called protocol-based pharmacotherapy management (PBPM), for warfarin therapy. The protocol requires pharmacists to manage timing of blood sampling for measuring PT-INR and warfarin dosage determination based on an algorithm. This study evaluated the efficacy of PBPM in warfarin therapy by comparing to conventional pharmaceutical care.

METHODS

From October 2013 to June 2015, a total of 134 hospitalized patients who underwent cardiovascular surgeries received post-operative warfarin therapy. The early series of patients received warfarin therapy as the conventional care (control group, n=77), whereas the latter received warfarin therapy based on the PBPM (PBPM group, n=68). These patients formed the cohort of the present study and were retrospectively analysed.

RESULTS

The indications for warfarin included aortic valve replacement (n=56), mitral valve replacement (n=4), mitral valve plasty (n=22) and atrial fibrillation (n=29). There were no differences in patients' characteristics between both groups. The percentage time in therapeutic range in the first 10 days was significantly higher in the PBPM group (47.1%) than that in the control group (34.4%, P<.005). The average time to reach the steady state was significantly (P<.005) shorter in the PBPM group compared to the control group (7.3 vs 8.6 days).

WHAT IS NEW AND CONCLUSION

Warfarin therapy based on our novel PBPM was clinically safe and resulted in significantly better anticoagulation control compared to conventional care.

Secretory Ig a in Saliva and Academic Stress

Several reports have proposed that the concentration of secretory immunoglobulin A (S-IgA) in saliva is an indicator of psychological stress. With this in mind, we decided to examine it in 10 second year medical student volunteers at Kawasaki Medical School course between May 4 and July 13, 2000 and discussed the relationship between S-IgA and the stress from academic examinations. Saliva was collected three times (on rising, at forenoon, and at bedtime) every Thursday. During this period, sporadic academic examinations were held twice and term-end examinations occurred during the last two weeks. Results showed the concentration of S-IgA significantly higher at the on rising time-point than at the other two time-points. There was also a tendency for the S-IgA level in saliva to be higher on the day before academic examinations and during them and lower on the days between these examinations. In addition, daily variations in the S-IgA concentration sometimes seemed to be disturbed by other academic stress. Therefore, it may be possible to use this measurement to monitor psychological stress in students and workers.

Qualitative diagnosis of hepatocellular carcinoma by contrast enhanced ultrasonography using Coded Harmonic Angio with Levovist

We attempted to evaluate diagnosis and characterization and to access therapeutic effects in cases of hepatocellular carcinoma (HCC) by contrast enhanced ultrasound (CEUS) using Coded Harmonic Angio (CHA) with Levovist, an intravenous ultrasound contrast agent. Fifty-seven HCC foci in 39 patients, including 37 HCC foci in 28 patients before and after transcatheter arterial chemoembolization or radio frequency ablation, were examined by CEUS using the CHA mode, which is under development. This mode uses digitally encoded pulse sequences that identify and suppress nonmoving tissue signals and enhance contrast signals from Levovist in a gray-scale format. In all cases, abundant tortuous intratumoral blood flow was visualized in the early vascular phase by continuous transmission, while tumor stain was recognized by consecutive 1-to-2 second intermittent transmission. Residual tumor area after treatment was also clearly depicted by intratumoral blood flow and partial enhancement. CEUS using CHA with Levovist is likely to become important in the qualitative diagnosis of hepatic tumor and to improve the efficacy of treatment for HCC.

Adjuvant Hepatic Arterial Infusion Chemotherapy After Resection for Pancreatic Cancer Using Coaxial Catheter-Port System Compared with Conventional System

PURPOSE

Previous reports have shown the effectiveness of adjuvant hepatic arterial infusion chemotherapy (HAIC) in pancreatic cancer. However, percutaneous catheter placement is technically difficult after pancreatic surgery. The purpose of this study was to evaluate the feasibility and outcome of HAIC using a coaxial technique compared with conventional technique for postoperative pancreatic cancer.

MATERIALS AND METHODS

93 consecutive patients who received percutaneous catheter-port system placement after pancreatectomy were enrolled. In 58 patients from March 2006 to August 2010 (Group A), a conventional technique with a 5-Fr indwelling catheter was used and in 35 patients from September 2010 to September 2012 (Group B), a coaxial technique with a 2.7-Fr coaxial catheter was used.

RESULTS

The overall technical success rates were 97.1 % in Group B and 86.2 % in Group A. In cases with arterial tortuousness and stenosis, the success rate was significantly higher in Group B (91.7 vs. 53.8 %; P = 0.046). Fluoroscopic and total procedure times were significantly shorter in Group B: 14.7 versus 26.7 min (P = 0.001) and 64.8 versus 80.7 min (P = 0.0051), respectively. No differences were seen in the complication rate. The 1 year liver metastasis rates were 9.9 % using the conventional system and 9.1 % using the coaxial system (P = 0.678). The overall median survival time was 44 months. There was no difference in the survival period between two systems (P = 0.312).

CONCLUSIONS

The coaxial technique is useful for catheter placement after pancreatectomy, achieving a high success rate and reducing fluoroscopic and procedure times, while maintaining the safety and efficacy for adjuvant HAIC in pancreatic cancer.

Switch of the magnetic field effect on photon upconversion based on sensitized triplet–triplet annihilation

Positive magnetic field effects on photon upconversion based on sensitized triplet–triplet annihilation are observed for the first time.