Despite a comprehensive study on the biosynthesis and function of nitric oxide, biological metabolism of nitric oxide, especially when its concentration exceeds the cytotoxic level, remains elusive. Oxidation of nitric oxide by O2 in aqueous solution has been known to yield NO2 –. On the other hand, a biomimetic study on the metal-mediated conversion of NO to NO2 –/NO3 – via O2 reactivity disclosed a conceivable pathway for aerobic metabolism of NO. During the NO-to-NO3 – conversion, transient formation of metal-bound peroxynitrite and subsequent release of •NO2 via O–O bond cleavage were evidenced by nitration of tyrosine residue or 2,4-di-tert-butylphenol (DTBP). However, the synthetic/catalytic/enzymatic cycle for conversion of nitric oxide into a nitrite pool is not reported. In this study, sequential reaction of the ferrous complex [(PMDTA)­Fe­(κ2-O,O′-NO2)­(κ1-O-NO2)] (3; PMDTA = pentamethyldiethylenetriamine) with NO(g), KC8, and O2 established a synthetic cycle, complex 3 → {Fe­(NO)2}9 DNIC [(PMDTA)­Fe­(NO)2]­[NO2] (4) → {Fe­(NO)2}10 DNIC [(PMDTA)­Fe­(NO)2] (1) → [(PMDTA)­(NO)­Fe­(κ2-O,N-ONOO)] (2) → complex 3, for the transformation of nitric oxide into nitrite. In contrast to the reported reactivity of metal-bound peroxynitrite toward nitration of DTBP, peroxynitrite-bound MNIC 2 lacks phenol nitration reactivity toward DTBP. Presumably, the [(PMDTA)­Fe] core in {Fe­(NO)}8 MNIC 2 provides a mononuclear template for intramolecular interaction between Fe-bound peroxynitrite and Fe-bound NO–, yielding Fe-bound nitrite stabilized in the form of complex 3. This [(PMDTA)­Fe]-core-mediated concerted peroxynitrite homolytic O–O bond cleavage and combination of the O atom with Fe-bound NO– reveals a novel and effective pathway for NO-to-NO2 – transformation. Regarding the reported assembly of the dinitrosyliron unit (DNIU) [Fe­(NO)2] in the biological system, this synthetic cycle highlights DNIU as a potential intermediate for nitric oxide monooxygenation activity in a nonheme iron system.

The Fermi bubbles are two large structures above and below the Galactic Plane. They are first discovered by Fermi-LAT and thought to be related to the jet or the wind from the Galactic center. The DArk Matter Particle Explorer (DAMPE) is a space-borne high energy particle telescope aiming at measuring cosmic rays and photons in a broad energy range. In this work, we use 4.8 years of DAMPE photon data to search for the emission from the Fermi Bubbles. We calculate the TS values of the lobes and the significance of its curved spectrum. The obtained spectral parameters are then compared with those from the Fermi-LAT. We also search for the emission from the cocoon in the southeast part of lobes. Since the Galactic diffuse emission (GDE) model is a major source of systematic uncertainty, we also switch to the GDE models calculated with Galprop and evaluate the influence.

Since its launch, in December 2015, the satellite-based DAMPE (DArk Matter Particle Explorer) particle detector is taking data smoothly. The Silicon-Tungsten tracKer-converter (STK) of DAMPE consists of six tracking planes (6x, 6y) of single-sided silicon micro-strip detectors mounted on seven support trays. The STK is able to measure the charge and precisely reconstruct the track of traversing charged particles. Tungsten plates (1 mm thick) are integrated in the second, third and fourth tray from the top to serve as γ → e + e − converters. Commissioned rapidly after the launch, the STK is running extremely well since then. The STK in-orbit calibration and performance during its first more than 5 years of operation, including the noise behaviour and the thermal and mechanical stability, will be presented in this contribution.

The DArk Matter Particle Explorer (DAMPE) is a satellite-borne experiment, in operation since 2015, aimed at studying high-energy gamma rays and cosmic nuclei fluxes. Of the various subdetectors in the DAMPE payload, the Silicon-Tungsten tracKer-converter (STK) plays a significant role in the charge measurement of incoming ions. Depending on the angle of inclination of the impinging particle and its position of impact on these strips, the collected charge can spread between the strips which results in some fractional signal loss. The η variable is used to identify this spread of charge across the strips and correct for the associated charge loss. This brings us closer to accurate determination of particle charge which is crucial for ensuring a good discrimination between particles. The η-correction is, therefore, expected to play an important role in the determination of heavy ions by the DAMPE detector. It has helped reduce the proton background for the helium identification in STK by a factor of 1.5 for MIP tracks. It has been sucessfully applied to carbon nuclei and its application to heavier nuclei is currently being studied.

Dark Matter Particle Explorer (DAMPE) is a calorimetric-type, satellite-borne detector. One important scientific object of DAMPE is to measure the flux of cosmic ray nuclei, which is fundamental for understanding the cosmic ray origin and propagation mechanism. Heavy nuclei beyond Iron in Cosmic Rays play an important role for studying the outstanding issues in the grand cycle of matter in the Galaxy. Thanks to the good charge resolution of the DAMPE PSD detector (∼0.06e for protons, ∼0.3e for iron), the primary charges in a wide range from proton (Z=1) to Zirconium (Z=40) can be identified. In seven years of data-taking from 2016 to 2022, DAMPE has collected data with more than 3 × 10 6 nuclei with Z≥26. In order to reduce the contamination of Iron in the flux of heavier nuclei in cosmic rays, new charge identification methods have been studied, and the relativistic rise effect has been corrected. Here, such tools and the methods of charge identification aiming to the spectrum measurement will be introduced.