The hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) play key roles in the conversion of energy derived from renewable energy sources into chemical energy. Efficient, robust, ...and inexpensive electrocatalysts are necessary for driving these reactions at high rates at low overpotentials and minimize energetic losses. Recently, electrocatalysts derived from hybrid metal phosphonate compounds have shown high activity for the HER or OER. We review here the utilization of metal phosphonate coordination networks and metal-organic frameworks as precursors/templates for transition-metal phosphides, phosphates, or oxyhydroxides generated in situ in alkaline solutions, and their electrocatalytic performance in HER or OER.
In liver the mitochondrial sirtuin, SIRT5, controls ammonia detoxification by regulating CPS1, the first enzyme of the urea cycle. However, while SIRT5 is ubiquitously expressed, urea cycle and CPS1 ...are only present in the liver and, to a minor extent, in the kidney. To address the possibility that SIRT5 is involved in ammonia production also in nonliver cells, clones of human breast cancer cell lines MDA-MB-231 and mouse myoblast C2C12, overexpressing or silenced for SIRT5 were produced. Our results show that ammonia production increased in SIRT5-silenced and decreased in SIRT5-overexpressing cells. We also obtained the same ammonia increase when using a new specific inhibitor of SIRT5 called MC3482. SIRT5 regulates ammonia production by controlling glutamine metabolism. In fact, in the mitochondria, glutamine is transformed in glutamate by the enzyme glutaminase, a reaction producing ammonia. We found that SIRT5 and glutaminase coimmunoprecipitated and that SIRT5 inhibition resulted in an increased succinylation of glutaminase. We next determined that autophagy and mitophagy were increased by ammonia by measuring autophagic proteolysis of long-lived proteins, increase of autophagy markers MAP1LC3B, GABARAP, and GABARAPL2, mitophagy markers BNIP3 and the PINK1-PARK2 system as well as mitochondrial morphology and dynamics. We observed that autophagy and mitophagy increased in SIRT5-silenced cells and in WT cells treated with MC3482 and decreased in SIRT5-overexpressing cells. Moreover, glutaminase inhibition or glutamine withdrawal completely prevented autophagy. In conclusion we propose that the role of SIRT5 in nonliver cells is to regulate ammonia production and ammonia-induced autophagy by regulating glutamine metabolism.
Escherichia coli is probably the best-known bacterial species and one of the most frequently isolated organisms from clinical specimens. Despite this, underappreciation and misunderstandings exist ...among medical professionals and the lay public alike regarding
E. coli as an extraintestinal pathogen. Underappreciated features include (i) the wide variety of extraintestinal infections
E. coli can cause, (ii) the high incidence and associated morbidity, mortality, and costs of these diverse clinical syndromes, (iii) the pathogenic potential of different groups of
E. coli strains for causing intestinal versus extraintestinal disease, and (iv) increasing antimicrobial resistance. In this era in which health news often sensationalizes uncommon infection syndromes or pathogens, the strains of
E. coli that cause extraintestinal infection are an increasingly important endemic problem and underappreciated “killers”. Billions of health care dollars, millions of work days, and hundreds of thousands of lives are lost each year to extraintestinal infections due to
E. coli. New treatments and prevention measures will be needed for improved outcomes and a diminished disease burden.
Development of quantitative theory of adsorption-induced deformation is important, e.g., for enhanced coalbed methane recovery by CO2 injection. It is also promising for the interpretation of ...experimental measurements of elastic properties of porous solids. We study deformation of mesoporous silica by n-pentane adsorption. The shape of experimental strain isotherms for this system differs from the shape predicted by thermodynamic theory of adsorption-induced deformation. We show that this difference can be attributed to the difference of disjoining pressure isotherm, responsible for the solid–fluid interactions. We suggest the disjoining pressure isotherm suitable for n-pentane adsorption on silica and derive the parameters for this isotherm from experimental data of n-pentane adsorption on nonporous silica. We use this isotherm in the formalism of macroscopic theory of adsorption-induced deformation of mesoporous materials, thus extending this theory for the case of weak solid–fluid interactions. We employ the extended theory to calculate solvation pressure and strain isotherms for SBA-15 and MCM-41 silica and compare it with experimental data obtained from small-angle X-ray scattering. Theoretical predictions for MCM-41 are in good agreement with the experiment, but for SBA-15 they are only qualitative. This deviation suggests that the elastic modulus of SBA-15 may change during pore filling.
Hypervirulent Klebsiella pneumoniae(hvKp) is an increasingly important pathogen. Tracking its epidemiology and evolving antimicrobial resistance will facilitate care.
A retrospective study was ...conducted in two hospitals. We collected the clinical data. Antimicrobial and virulence-associated phenotype and genotype, sequence type, and whole genome sequencing of selected strains were performed. HvKp was defined by the presence of some combination of
p
rmpA,
p
rmpA2, iucA, iroB, and peg-344, genes shown to accurately identify hvKp.
Of 158 Kp clinical isolates, 79 (50%) were hvKp. Interestingly, 53/79 (67.1%) of hvKp strains were isolated from patients with nosocomial infection and 19/79 (24.1%) from patients with healthcare-associated infection, but only 7/79 (8.8%) from patients with community-acquired infections. Importantly, 27/53 (50.9%) and 4/19 (21.1%) of hvKp nosocomial and healthcare-associated isolates, respectively, were multi-drug-resistant (MDR); 25/53 (47.2%) and 5/19 (26.3%) expressed ESBLs and 14/53 (26.4%) and 2/19 (10.5%) were carbapenem-resistant. Of the hvKp isolates from community-acquired infection, 0/7 (0%) were MDR and 0/7 (0%) were carbapenem-resistant. Additionally, unique characteristics of nosocomial, healthcare-associated, and community-acquired hvKp infection were identified. In summary, 50% of K. pneumoniae infections were caused by hvKp. A concerning, novel finding from this report is a major shift in hvKp epidemiology. Ninety-one percent of hvKp infections were nosocomial or healthcare-associated, and 43.1% of these isolates were MDR.
These data suggest that hvKp may be replacing classical K. pneumoniae as the dominant nosocomial and healthcare-associated pathotype. Ongoing surveillance is needed to determine if this trend is occurring elsewhere.
Titanium dioxide is a promising anode for efficient lithium‐ion storage in terms of low cost, good structural stability, and inherent safety. However, its performance in Li‐ion storage is hindered by ...poor electronic conductivity. In this work, a solvothermal approach was applied for the synthesis of Nb‐doped TiO2 nanocrystals with Nb content up to 33 at. %. The enhanced electronic conductivity and favorable electrochemical kinetics led to superior specific capacity, rate capability, and cycling stability compared to pristine TiO2. For the optimum dopant content of 21 at. %, a specific capacity of 58 mAh g−1 was reached at 10 A g−1 compared to just 28 mAh g−1 for pure TiO2, in addition to almost 20 % higher capacity retention after prolonged cycling. The strategy in the current work can be easily extended to the design of other high‐performance electrode materials for energy storage.
Crystal clear: Benefitting from the enhanced electronic conductivity and favorable electrochemical kinetics, Nb‐doped TiO2 nanocrystals, which are synthesized via a simple solvothermal method, display outstanding electrochemical performance compared to pure TiO2.
Dentin collagen is a major component of the hybrid layer, and its stability may have
a great impact on the properties of adhesive interfaces. We tested the hypothesis
that the use of tannic acid ...(TA), a collagen cross-linking agent, may affect the
mechanical properties and stability of the dentin matrix. The present study evaluated
the effects of different concentrations of TA on the modulus of elasticity and
enzymatic degradation of dentin matrix. Hence, the effect of TA pre-treatment on
resin-dentin bond strength was assessed with the use of two bonding systems. Sound
human molars were used and prepared according to each experimental design. The use of
TA affected the properties of demineralized dentin by increasing its stiffness. TA
treatment inhibited the effect of collagenase digestion on dentin matrix,
particularly for 10%TA and 20%TA. The TA-dentin matrix complex resulted in improved
bond strength for both adhesive systems.
PURPOSE OF REVIEWTwo pathotypes of Klebsiella pneumoniae cause human infections, classical (cKp) and hypervirulent (hvKp) K. pneumoniae. The present understanding of genetic elements, the need for an ...accurate test to identify hvKp, the clinical implications of infection, the knowledge gap on how and why hvKp colonization transitions to infection, and potential infection prevention and control issues for hvKp are discussed.
RECENT FINDINGSInfections because of hvKp are increasingly recognized worldwide. Its ability to cause organ and life-threatening disease in healthy individuals from the community merits concern, which has been magnified by increasing descriptions of multiply drug-resistant (MDR) and extensively drug-resistant (XDR) strains. Increased capsule and siderophore production by hvKp relative to cKp are critical virulence traits. Asians are most commonly infected, but whether this is mediated by a genetic susceptibility, or increased exposure and colonization is unknown. Specific studies about the epidemiology and transmission of hvKp are lacking, but precautions are appropriate for MDR/XDR strains and perhaps all infected/colonized individuals.
SUMMARYhvKp is evolving into an increasingly concerning pathogen, in part because of the development of XDR strains. An accurate test to identify hvKp is needed for optimal clinical care, epidemiological, and research studies. An improved understanding of how infection develops, if a genetic susceptibility exists, and appropriate infection prevention and control measures also are needed.
Cyanobacteria are photosynthetic prokaryotes of high ecological and biotechnological relevance that have been cultivated in laboratories around the world for more than 70 years. Prolonged laboratory ...culturing has led to multiple microevolutionary events and the appearance of a large number of 'domesticated' substrains among model cyanobacteria. Despite its widespread occurrence, strain domestication is still largely ignored. In this work we describe Synechococcus elongatus PCC 7942-KU, a novel domesticated substrain of the model cyanobacterium S. elongatus PCC 7942, which presents a fast-sedimenting phenotype. Under higher ionic strengths the sedimentation rate increased leading to complete sedimentation in just 12 h. Through whole genome sequencing and gene deletion, we demonstrated that the Group 3 alternative sigma factor F plays a key role in cell sedimentation. Further analysis showed that significant changes in cell surface structures and a three-fold increase in released polysaccharides lead to the appearance of a fast-sedimenting phenotype. This work sheds light on the determinants of the planktonic to benthic transitions and provides genetic targets to generate fast-sedimenting strains that could unlock cost-effective cyanobacterial harvesting at scale.
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