Tailoring the reducibility and catalytic activity of CuO nanoparticles for low temperature CO oxidation

Copper oxide (CuO) nanoparticles have received considerable interest as active and inexpensive catalysts for various gas–solid reactions. The CuO reducibility and surface reactivity are of crucial importance for the high catalytic activity. Herein, we demonstrate that the reducibility and stability of CuO nanoparticles can be controlled and tailored for the high catalytic activity of CO oxidation. The synthesized CuO nanoparticles possessed enhanced reducibility in CO atmosphere at lower reduction temperature of 126 °C compared to 284 °C for that of reference CuO particles. Moreover, the CuO catalysts with tailored reducibility demonstrated a reaction rate of 35 μmol s⁻¹ g⁻¹ and an apparent activation energy of 75 kJ mol⁻¹. Furthermore, the tailored catalysts exhibited excellent long-term stability for CO oxidation for up to 48 h on stream. These readily-reducible CuO nanoparticles could serve as efficient, inexpensive and durable catalysts for CO oxidation at low temperatures.

Copper oxide (CuO) nanoparticles of tailored reducibility could be used as inexpensive, efficient and durable catalysts for CO oxidation at low temperature.     

Correction to: Prenatal attachment: Using measurement invariance to test the validity of comparisons across eight culturally diverse countries

Archives of Women's Mental Health - A Correction to this paper has been published: https://doi.org/10.1007/s00737-021-01122-7     

Influence of parity on bone mineral density and peripheral fracture risk in Moroccan postmenopausal women

The aims of the study were to determine: (1) the relationship between parity and bone mineral density (BMD); (2) the relationship between parity and osteoporotic peripheral fractures.

Material and methods

The group studied included 730 postmenopausal women. Patients were separated into four groups according to the number of fullterm pregnancies, group 1: nulliparae, group 2: one to three pregnancies, group 3: four to five pregnancies, and group 4: six and more pregnancies. Additionally, patients were separated into three groups according to their ages, as <50 years, 50–59 years and ≥60 years.

Results

The median parity was 4 [0–20]. All the patients with parity greater than six had spine and hip BMD values significantly lower than values in the other groups (p < 0.001). After adjustment for age and body mass index (BMI), decreased lumbar and total hip BMD were still associated to increased parity (analysis of covariance (ANCOVA), p = 0.04 and 0.023, respectively). The relation between parity and lumbar BMD was highly significant among women aged <50 years (age-adjusted p = 0.022), while there was no parity-spine BMD association in the other age groups. The relation between parity and hip BMD was seen only in the group 50–59 years (age-adjusted p = 0.042). A positive history for peripheral fractures was present in 170 (23%) patients. There was relationship between parity and peripheral fractures neither in the whole population nor in the sub-groups according to age.

Discussion

The present study suggests that the BMD of the spine and hip decreases with an increasing number of pregnancies, and this situation shows variations in different age groups. However, there was no correlation between parity level and peripheral fractures.     

Platelet formation is the consequence of caspase activation within megakaryocytes

Platelets are formed from mature megakaryocytes (MKs) and arise from the development of long and thin cytoplasmic extensions called proplatelets. After platelet release, the senescent MKs (nucleus surrounded by some cytoplasm) undergo cell death by apoptosis. To explore the precise role of apoptosis in proplatelet formation, we grew human MKs from CD34(+) cells and assessed the possible role of caspases. Proteolytic maturation of procaspase-3 and procaspase-9 was detected by immunoblots in maturing MKs as well as in proplatelet-bearing MKs and senescent MKs. Cleavage of caspase substrates such as gelsolin or poly adenosine diphosphate (ADP)-ribose polymerase (PARP) was also detected. Interestingly, activated forms of caspase-3 were detected in maturing MKs, before proplatelet formation, with a punctuate cytoplasmic distribution, whereas a diffuse staining pattern was seen in senescent and apoptotic MKs. This localized activation of caspase-3 was associated with a mitochondrial membrane permeabilization as assessed by the release of cytochrome c, suggesting an activation of the intrinsic pathway. Moreover, these MKs with localized activated caspase-3 had no detectable DNA fragmentation. In contrast, when apoptosis was induced by staurosporine, diffuse caspase activation was seen; these MKs had signs of DNA fragmentation, and no proplatelet formation occurred. The pan-caspase inhibitor z-VAD.fmk as well as more specific inhibitors of caspase-3 and caspase-9 blocked proplatelet formation, whereas an inhibitor of calpeptin had no effect. Overexpression of Bcl-2 also inhibited proplatelet formation in maturing MKs. Thus, localized caspase activation is causal to proplatelet formation. We conclude that proplatelet formation is regulated by a caspase activation limited to only some cellular compartments.     

Medical research during the COVID-19 pandemic

The current pandemic of coronavirus disease 2019 (COVID-19) which was first detected in Wuhan, China in December 2019 is caused by the novel coronavirus named severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). The virus has quickly spread to a large number of countries leading to a great number of deaths. Unfortunately, till today there is no specific treatment or vaccination for SARS-CoV-2. Most of the suggested treatment medications are based on in vitro laboratory investigations, experimental animal models, or previous clinical experience in treating similar viruses such as SARS-CoV-1 or other retroviral infections. The running of any clinical trial during a pandemic is affected at multiple levels. Reasons for this include patient hesitancy or inability to continue investigative treatments due to self-isolation/quarantine, or limited access to public places (including hospitals). Additional barriers relate to health care professionals being committed to other critical tasks or quarantining themselves due to contact with COVID-19 positive patients. The best research approaches are those that adapt to such external unplanned obstacles. Ongoing clinical trials before COVID-19 pandemic have the potential for identifying important therapies in the long-term if they can be completed as planned. However, these clinical trials may require modifications due a pandemic such as this one to ensure the rights, safety, and wellbeing of participants as well as medical staff involved in the conduction of clinical trials. Clinical trials initiated during the pandemic must be time-efficient and flexible due to high contagiousness of severe acute respiratory syndrome coronavirus 2, the significant number of reported deaths, and time constraints needed to perform high quality clinical trials, enrolling adequate sample sizes. Collaboration between different countries as well as implementation of innovative clinical trial designs are essential to successfully complete such initiatives during the current pandemic. Studies looking at the long term sequalae of COVID-19 are also of importance as recent publications describe multi-organ involvement. Long term follow-up of COVID-19 survivors is thus also important to identify possible physical and mental health sequellae.     

Imaging of perianal granular cell tumor with lung metastasis: A case report and literature review

The granular cell tumor or Abrikossoff''s tumor is a rare tumor, most often benign in evolution. Malignant forms are exceptional. We report, here, a very rare case of granular cell tumor, localized in the perianal region, in a 54-year-old woman with lung metastases. CT and MRI with contrast showed a locally advanced tumor process in the right para-anal region associated with multiple "balloon release" lung lesions. The diagnosis was confirmed by immunostaining after surgical biopsy. Very few cases of malignant granular cell tumors with lung metastasis have been reported in the literature.