Planar Hexacoordinate Beryllium: Covalent Bonding Between s-block Metals

Achieving a planar hypercoordinate arrangement of s-block metals through covalent bonding with ligands is challenging due to the strong ionicity involved. Herein, we report the first case of a neutral binary global minimum containing a planar hexacoordinate beryllium atom. The central Be atom is coordinated by six active Be atoms, the latter in turn are enclosed by an equal number of more electronegative chlorine atoms in the periphery, forming a star-like phBe cluster (Be©Be6 Cl6 ). Importantly, the cluster exhibits dynamically stabilized stemming geometrically from the appropriate matching of metal-ligand size and electronically from adherence to the octet rule as well as possessing a 6σ/2π double aromaticity. Remarkably, energy decomposition analysis-natural orbitals for chemical valence (EDA-NOCV) analysis reveals a significant covalent interaction between the ligand and the central metal beryllium atoms, a fact further supported by a large Wiberg bond index. This cluster is a promising synthetic as its excellent electronic, dynamic and thermodynamic stability.

Bioinspired PROTAC-induced macrophage fate determination alleviates atherosclerosis

Atherosclerosis is a major cause of death and disability in cardiovascular disease. Atherosclerosis associated with lipid accumulation and chronic inflammation leads to plaques formation in arterial walls and luminal stenosis in carotid arteries. Current approaches such as surgery or treatment with statins encounter big challenges in curing atherosclerosis plaque. The infiltration of proinflammatory M1 macrophages plays an essential role in the occurrence and development of atherosclerosis plaque. A recent study shows that TRIM24, an E3 ubiquitin ligase of a Trim family protein, acts as a valve to inhibit the polarization of anti-inflammatory M2 macrophages, and elimination of TRIM24 opens an avenue to achieve the M2 polarization. Proteolysis-targeting chimera (PROTAC) technology has emerged as a novel tool for the selective degradation of targeting proteins. But the low bioavailability and cell specificity of PROTAC reagents hinder their applications in treating atherosclerosis plaque. In this study we constructed a type of bioinspired PROTAC by coating the PROTAC degrader (dTRIM24)-loaded PLGA nanoparticles with M2 macrophage membrane (MELT) for atherosclerosis treatment. MELT was characterized by morphology, size, and stability. MELT displayed enhanced specificity to M1 macrophages as well as acidic-responsive release of dTRIM24. After intravenous administration, MELT showed significantly improved accumulation in atherosclerotic plaque of high fat and high cholesterol diet-fed atherosclerotic (ApoE-/-) mice through binding to M1 macrophages and inducing effective and precise TRIM24 degradation, thus resulting in the polarization of M2 macrophages, which led to great reduction of plaque formation. These results suggest that MELT can be considered a potential therapeutic agent for targeting atherosclerotic plaque and alleviating atherosclerosis progression, providing an effective strategy for targeted atherosclerosis therapy.

3-D molecular stars with covalent axial bonding

In designing three-dimensional (3-D) molecular stars, it is very difficult to enhance the molecular rigidity through forming the covalent bonds between the axial and equatorial groups because corresponding axial groups will generally break the delocalized π bond over equatorial frameworks and thus break their star-like arrangement. In this work, exemplified by designing the 3-D stars Be₂ ©Be₅ E₅ ⁺ (E = Au, Cl, Br, I) with three delocalized σ bonds and delocalized π bond over the central Be₂ ©Be₅ moiety, we propose that the desired covalent bonding can be achieved by forming the delocalized σ bond(s) and delocalized π bond(s) simultaneously between the axial groups and equatorial framework. The covalency and rigidity of axial bonding can be demonstrated by the total Wiberg bond indices of 1.46-1.65 for axial Be atoms and ultrashort Be-Be distances of 1.834-1.841 Å, respectively. Beneficial also from the σ and π double aromaticity, these mono-cationic 3-D molecular stars are dynamically viable global energy minima with well-defined electronic structures, as reflected by wide HOMO-LUMO gaps (4.68-5.06 eV) and low electron affinities (4.70-4.82 eV), so they are the promising targets in the gas phase generation, mass-separation, and spectroscopic characterization.

[Identification of Chinese herbs in the Qing Royals--Fu Shen and Fu Shen Mu]

The use of Fu Shen and Fu Shen Mu as medicines has had a long history. Today Fu Shen is still taken as bulk medicinal materials, whereas Fu Shen Mu had disappeared in the medical market. Fu Shen, Yun Fu Shen, Bai Fu Shen, and Bao Mu Fu Shen were used in clinical application in the Qing Royals. Bai Fu Shen and Fu Shen Mu are still kept as speciment in the Palace Museum today. It was found that Bai Fu Shen in the Qing Royals was the same as Fu Shen after peeling and pine roots recorded in the herbal literatures of the Ming and Qing dynasties, with their character tests and historical analysis. It can be inferred that Fu Shen, Yun Fu Shen and Bai Fu Shen recorded in the Qing Royals were actually Fu Shen, with pine roots in sclerotia and after peeling and pine roots removed in processing. Bao Mu Fu Shen and Bao Fu Shen should refer to Fu Shen with pine roots. Fu Shen Mu should mean Fu Shen without white sclerotia and peel during processing. Fu Shen, currently used clinically, is Bao Mu Fu Shen in the Qing Dynasty. Fu Shen distinguishes greatly from Fu Shen Mu in their effects. Such identification and analysis of herbs provides a way of thinking for further hurb studies of the Qing Dynasty.

[The necessity of post-maneuver postural restriction in treating posterior canal benign paroxysmal positional vertigo: a Meta-analytic study]

Objective: We conducted a Meta-analysis to investigate the necessity of postural restrictions after manual reduction in the treatment of posterior canal benign paroxysmal positional vertigo (PC-BPPV). Methods: We searched PubMed, EBSCO, Proquest, Web of Science databases, Ovid, and screened eligible studies that investigated the effect of post-maneuver postural restriction in treating patients with PC-BPPV. Outcomes included the efficacy of treatment and recurrence. Meta-analysis was performed using Stata 15.0 software. Results: Studies of the single visit efficiency included 11 references, with a sample size of 1 733 cases. The Meta-analysis results showed that the difference in the efficacy between the postural restricted group and the non-postural restricted group in PC-BPPV patients was statistically significant(RR=1.12, 95%CI=1.07-1.18, P<0.001). There were 12 references included in the study on the total efficiency, with a cumulative sample size of 1763 cases. There was no statistically significant difference between the effect of postural restriction after manipulative reduction and that of simple manipulative reduction (RR=1.03, 95%CI=0.99-1.08, P=0.118). There were 5 references included in the study of recurrence rate, and the cumulative sample size was 659 cases. There was no statistically significant difference in the recurrence rate between the postural restricted group and the non-postural restricted group(RR=0.98, 95%CI=0.62-1.54, P=0.937). Conclusions: In comparison with non-postural restriction group, post-maneuver postural restriction after a single visit can improve the treatment effective rate of PC-BPPV and contribute to the improvement in the symptoms of patients in a short term. However, postural restrictions has no significant effect on the final prognosis of PC-BPPV, and it also has no significant effect on the recurrence.

Transition metal chemistry in synthetically viable alkaline earth complexes M(Cp)3- (M = Ca, Sr, Ba)

We predicted the stable alkaline earth complexes M(Cp)3- (M = Ca, Sr, Ba; Cp = cyclopentadienyl), where the M centers were in their stable +2 oxidation state and mimicked the bonding behaviour of transition metals by participating in bonding with the π orbitals of Cp ligands using their d orbitals.

Influence of stepwise oxidation on the structure, stability, and properties of planar pentacoordinate carbon species CAl5. Phys Chem Chem Phys 2020;22:17062-17067. [PMID: 32568316 DOI: 10.1039/d0cp01106a]

Computational design has played an important role in planar hyper-coordinate carbon (phC) chemistry. However, none of numerous computationally predicted phC species were subsequently successfully synthesized in the condensed phase, perhaps due to the frustrating issue of oxidation. In the present work, we studied the influence of stepwise oxidation on the structure, stability, and properties of phC species using the milestone planar pentacoordinate carbon (ppC) species CAl₅⁺ as an example. Our results indicated that the ppC structure of CAl₅⁺ would be directly destroyed with one, two, or six O atom(s) per molecule present and indirectly with three or four O atoms, but maintained with five O atoms due to the ppC isomer of CAl₅O₅⁺ being a kinetically stable global energy minimum displaying σ and π double aromaticity. Moreover, the magnitudes of the first to fifth vertical oxygen affinities (VOAs) for CAl₅⁺ were determined to be very high (-85.5 to -116.3 kcal mol^-1), probably due to the existence of peripheral diffuse Al-Al bond(s). However, the sixth VOA was reduced significantly to -50.2 kcal mol^-1, consistent with the absence of any diffuse Al-Al bond in the corresponding CAl₅O₅⁺ species. So CAl₅O₅⁺ may be insensitive to oxidation. Therefore, the ppC species D_5h CAl₅O₅⁺ might be resistant to being degraded under a delicate control of oxidation level (producing five O atoms per CAl₅⁺ molecule).

Radio frequency measurement and tuning of a 13 MeV Alvarez-type drift tube linac for a compact pulsed hadron source

This paper describes the radio frequency (RF) measurement and tuning result of a 13 MeV Alvarez-type drift tube linac (DTL) for a compact pulsed hadron source (CPHS) at Tsinghua University. The design, machining, assembly, and alignment of the DTL are presented for integrity. The CPHS project consists of a high-current proton linac (13 MeV, 16 kW, peak current of 50 mA, 0.5 ms pulse width at 50 Hz), a neutron target station, a small-angle neutron scattering instrument, and a neutron imaging/radiology station. The linac contains an electron cyclotron resonance ion source, a low energy beam transport line, a four-vane radio frequency quadrupole (RFQ) accelerator, an Alvarez-type DTL, a high energy beam transport line, and a RF power supply and distributor. Construction on the CPHS started in June 2009, and the CPHS has provided 2000 h since 2013 to users with the neutrons produced by the 3 MeV proton beam from the radio frequency quadrupole bombarding on the beryllium target as an achievement of its mid-term objective. Presently, the tuning of the assembled DTL cavity has been completed successfully. The 4.3-m-long DTL consists of 40 accelerating cells, among which 39 full-length drift tubes (DTs) are suspended inside the cavity, and two half-length DTs are mounted inside the two end flanges of the cavity. Each DT contains a permanent magnet quadrupole. Thirteen post couplers and nine tuners are available for the tuning of the field. The relative error of the field after tuning is within ±1.6%, with a tilt sensitivity within ±33%/MHz in all cells. The beam energy will reach its designed value of 13 MeV after the DTL is installed in the beam line downstream the 3 MeV RFQ accelerator.

[A 2-year cohort study on the caries risk assessment of 3-year-old caries-free children using Cariostat caries activity test]

Objective: To evaluate the caries status of a cohort of 3-year-old caries-free children from 2 kindergartens in Beijing in a period of 2 years by using Cariostat caries activity test and to assess the sensitivity and specificity of Cariostat score as a caries risk indicator for caries-free children. Methods: Totally 426 3-year-old caries-free children from 2 kindergartens in Beijing were recruited in the present study. Informed consents were obtained from the children's parents. Dental plaque samples of the children were collected and the Cariostat caries activity tests were conducted at baseline and once a year for 2 years. After two years, the caries status of the cohort children were re-evaluated and the caries incidences amongst children with high (2.0, 2.5, 3.0), medium (1.5) and low (1.0, 0.5, 0.0) levels of Cariostat scores were compared and analyzed. Results: Totally 864 3-year-old children from 2 kindergartens were screened before the study startedand 426 (49.3%) children were caries free. After 2-year follow-up, 312 out of 426 (73.2%) remained in the study. The overall caries incident rate was 46.5% (145/312). The caries incident rate of children with high level of Cariostat scores was 88.9% (88/99), while the caries incident rates of children with medium and low levels of Cariostat scores was 38.7% (36/93) and 17.5% (21/120), respectively. The sensitivity and specificity of the Cariostat test in assessing the caries risk of 3-year-old caries-free children in a period of 2 years were 60.7% and 93.4%, respectively. Conclusions: Cariostat caries activity test can be used as an indicator to predict the caries risk of 3-year-old caries-free children. Comprehensive caries management could be conducted for children in kindergartens based on the caries risk assessment results of caries experience and the Cariostat score.

Inhibition effect of silver nanoparticles on herpes simplex virus 2

The herpes simplex virus 2 (HSV-2) is one of the most important sexually transmitted pathogens, and can facilitate the spread of human immunodeficiency virus. The currently available antiviral drugs have certain limitations. Nanosilver has received increasing attention recently with respect to its antibacterial and antiviral properties. The purpose of this study was to determine the inhibiting effect and mechanism of silver nanoparticles (Ag-NPs) on HSV-2. The cytotoxicity of Vero cells induced by different Ag-NP concentrations was investigated by using the methyl thiazolyl tetrazolium (MTT) assay. The inhibiting effect of Ag-NPs on HSV-2 at various times was also evaluated by using a plaque assay. The toxicity of 100 μg/mL Ag-NPs on Vero cells was very low. The mixture of Ag-NP suspension and HSV-2 prior to infecting cells could significantly inhibit the production of progeny viruses. Ag-NPs also inhibited the replication of HSV-2 for 24 h before infecting cells with HSV-2. Therefore, 100 μg/mL Ag-NPs could completely inhibit HSV-2 replication. Ag-NPs at nontoxic concentrations were capable of inhibiting HSV-2 replication when administered prior to viral infection or soon after initial virus exposure. This suggests that the mode of action of Ag-Nps occurs during the early phases of viral replication.

Toxicokinetics of naringin and its metabolite naringenin after 180-day repeated oral administration in beagle dogs assayed by a rapid resolution liquid chromatography/tandem mass spectrometric method

Toxicokinetic characteristics of naringin and its metabolite naringenin were investigated in beagle dogs after oral administration of naringin at the doses of 20, 100, or 500 mg/kg/day in a repeated-dose study for 1, 30, 90, and 180 days. Plasma concentrations of naringin and naringenin were determined by a rapid resolution liquid chromatography/electrospray ionization/tandem mass spectrometric method. The results showed that no differences in systemic exposure were observed between male and female beagle dogs. Systematic exposure exhibited dose-dependent increase for both naringin and naringenin. No significant accumulations were observed. Results would be taken into consideration for the interpretation of toxicology findings and provide a reference for clinical safety assessment.

Compensatory caspase activation in MPP+-induced cell death in dopaminergic neurons

Many have hypothesized that cell death in Parkinson's disease is via apoptosis and, specifically, by the mitochondrial-mediated apoptotic pathway. We tested this hypothesis using a mouse dopaminergic cell line of mesencephalic origin, MN9D, challenged with the Parkinsonism-causing neurotoxin MPP+ (1-methyl-4-phenylpyridinium ion). Apoptosis was the main mode of cell death when the cells were subjected to MPP+ treatment under serum-free conditions for 24 h. Caspase-3 and caspase-9, however, were not activated, thus indicating the existence of alternate or compensatory cell death pathway(s) in dopaminergic neuronal cells. Using caspase inhibitors, we demonstrated that these pathways involve caspase-2, -8, -6 and -7. A time-course study indicated that activation of caspase-2 and -8 occurred upstream of caspase-6 and caspase-7. Upon MPP+ challenge, the apoptosis-inducing factor was translocated from the mitochondria into the MN9D cytosol and nucleus. These results suggest the existence of alternative apoptotic pathways in dopaminergic neurons.

Soft tissue chondroma of the parapharyngeal space: a case report

Benign chondroma affecting the soft tissues is uncommon. This tumour is particularly rare in the neck. We present the first case of soft tissue chondroma arising in the parapharyngeal space of a 20-year-old man with a two-year history of a gradual sensation of a swelling in the pharynx with increasing snoring. The CT and pathological features of this lesion will be discussed. We suggest that a peroral approach should be considered for benign parapharyngeal tumour which has been demonstrated on imaging to be in the anterior parapharyngeal space, especially for tumours that are medial to the pterygoid muscles even though the tumour is a large one.