Mechanistic Understanding and Rational Design of Quantum Dot/Mediator Interfaces for Efficient Photon Upconversion.

The semiconductor-nanocrystal-sensitized, three-component upconversion system has made great strides over the past 5 years. The three components (i.e., triplet photosensitizer, mediator, and emitter) each play critical roles in determining the input and output photon energy and overall quantum efficiency (QE). The nanocrystal photosensitizer converts the absorbed photon into singlet excitons and then triplet excitons via intersystem crossing. The mediator accepts the triplet exciton via either direct Dexter-type triplet energy transfer (TET) or sequential charge transfer (CT) while extending the exciton lifetime. Through a second triplet energy-transfer step from the mediator to the emitter, the latter is populated in its lowest excited triplet state. Triplet-triplet annihilation (TTA) between two triplet emitters generates the emitter in its bright singlet state, which then emits the upconverted photon. Quantum dots (QD) have a tunable band gap, large extinction coefficient, and small singlet-triplet energy losses compared to metal-ligand charge-transfer complexes. This high triplet exciton yield makes QDs good candidates for photosensitizers. In terms of driving triplet energy transfer, the triplet energy of the mediator should be slightly lower than the triplet exciton energy of the QD sensitizer for a downhill energy landscape with minimal energy loss. The same energy cascade is also required for the transfer from the mediator to the emitter. Finally, the triplet energy of the emitter must be slightly larger than one-half of its singlet energy to ensure that TTA is exothermic. Optimization of the sensitizer, mediator, and emitter will lead to an increase in the anti-Stokes shift and the total quantum efficiency. Evaluating each individual step's efficiency and kinetics is necessary for the understanding of the limiting factors in existing systems.This review summarizes chalcogenide QD-based photon upconversion systems with a focus on the mechanistic aspects of triplet energy transfer conducted by the Tang and Lian groups. Via time-resolved spectroscopy, the rates and major loss pathways associated with the two triplet energy-transfer steps were identified. The studies are focused on the near-infrared (NIR) to visible (VIS) PbS-tetracene-based systems as they allow systematic control of the QD, mediator, and emitter. Our results show that the mediator triplet state is mostly formed by direct TET from the QD and the transfer rate is influenced by the density of bound mediator molecules. Charge transfer, a loss pathway, does not produce triplet excitons and can be minimized by adding an inert shell to the QD. This transfer rate decreases exponentially with the distance between the QD and mediator molecule. The second TET rate was found to be much slower than the diffusion-limited collision rate, which results in the triplet lifetime of the mediator being the main factor limiting its efficiency. Finally, the total quantum efficiency can be calculated using these measured quantities including the TET1 and TET2 efficiencies. The agreement between calculated and measured quantum efficiencies suggests a firm understanding of QD-sensitized photon upconversion. We believe the above conclusions are general and should be widely applicable to similar systems, including singlet fission in hybrid organic-nanocrystal materials.

A Rapid Label-Free Disposable Electrochemical Salivary Point-of-Care Sensor for SARS-CoV-2 Detection and Quantification.

The coronavirus disease 2019 (COVID-19) pandemic has created an urgent need for accurate early diagnosis and monitoring. A label-free rapid electrochemical point-of-care (POC) biosensor for SARS-CoV-2 detection in human saliva is reported here to help address the shortcomings of traditional nucleic acid amplification methods and give a quantitative assessment of the viral load to track infection status anywhere, using disposable electrochemical sensor chips. A new chemical construct of gold nanoparticles (GNp) and thionine (Th) are immobilized on carboxylic acid functionalized carbon nanotubes (SWCNT-COOH) for high-performance biosensing. The sensor uses saliva with a one-step pretreatment and simple testing procedure as an analytical medium due to the user-friendly and non-invasive nature of its procurement from patients. The sensor has a response time of 5 min with a limit of detection (LOD) reaching 200 and 500 pM for the freely suspended spike (S) protein in phosphate buffer saline (PBS) and human saliva, respectively. The sensor's performance was also proven for detecting a COVID-19 pseudovirus in an electrolyte solution with a LOD of 106 copies/mL. The results demonstrate that the optimized POC sensor developed in this work is a promising device for the label-free electrochemical biosensing detection of SARS-CoV-2 and different species of viruses.

Development of a prognostic model based on an immunogenomic landscape analysis of colorectal cancer.

Screening and therapeutic programs for colorectal cancer (CRC) are invasive or not effective and unable to meet patient needs. Major advances in immunogenomics may change this status but need more exploration. Differentially expressed genes and immune-related genes (IRGs) were identified by computational methods. A prognostic model was established and validated based on survival-related IRGs via stepwise multivariate Cox regression analysis. Nine IRGs were selected and identified as survival-related genes. A 7-gene prognostic model could offer a preliminary and valid determination of risk in CRC patients. The area under the curve of the receiver operating characteristic was 0.672. The 7-gene prognostic model might be used as a novel prognostic tool in CRC patients.

Apocynin ameliorates cognitive deficits in streptozotocin-induced diabetic rats.

AIMS: The aim was to investigate the improvement properties of apocynin and its potential mechanism on diabetes-associated cognitive decline. METHODS: In this study, the model of diabetic rat was established by STZ (50 mg/kg) and treated with apocynin (16 mg/kg/d for 12 weeks). The cognitive ability was evaluated by Morris water maze test. The indicators of oxidative stress (SOD and MDA) were analyzed by spectrophotometer. The inflammatory cytokines were measured by real time-PCR and ELISA. The protein expressions of Nrf-2, HO-1, Bcl-2 and Bax were determined by Western blot. RESULTS: Treatment with apocynin ameliorated diabetes-related learning and memory injury, as represented by decreasing escape latency and enhancement of the number of times of crossing platform, in the Morris water maze test. In hippocampus, apocynin markedly augmented SOD activity and inhibited MDA level to alleviate oxidative stress. Moreover, apocynin obviously relieved inflammatory reaction by suppressing TNF-α, IL-1ß and IL-6 concentrations. Concomitantly, apocynin also statistically enhanced Nrf-2 and HO-1 protein expression to improve DACD. Lastly, apocynin notably ameliorated Bax/Bcl-2 ratio by regulating Bax and Bcl-2 protein expression to mitigate apoptosis. CONCLUSION: Our results have shown that apocynin may be a valid therapeutic agent against DACD via modulation of antioxidant, anti-inflammatory, and anti-apoptosis (Tab. 1, Fig. 18, Ref. 35).

Low temperature radical initiated hydrosilylation of silicon quantum dots.

The photophysics of silicon quantum dots (QDs) is not well understood despite their potential for many optoelectronic applications. One of the barriers to the study and widespread adoption of Si QDs is the difficulty in functionalizing their surface, to make, for example, a solution-processable electronically-active colloid. While thermal hydrosilylation of Si QDs is widely used, the high temperature typically needed may trigger undesirable side-effects, like uncontrolled polymerization of the terminal alkene. In this contribution, we show that this high-temperature method for installing aromatic and aliphatic ligands on non-thermal plasma-synthesized Si QDs can be replaced with a low-temperature, radical-initiated hydrosilylation method. Materials prepared via this low-temperature route perform similarly to those created via high-temperature thermal hydrosilylation when used in triplet fusion photon upconversion systems, suggesting the utility of low-temperature, radical-initiated methods for creating Si QDs with a range of functional behavior.

Survival advantage of initiating dialysis in elderly and non-elderly incident end-stage kidney disease patients.

AIM: Many patients, especially the elderly, who require renal replacement therapies (RRT) have delayed or rejected dialysis for various reasons. Current dialysis guidelines may not be relevant for the elderly or frail patients. We aim to determine survival advantage of initiating dialysis in patients deemed to require RRT. METHODS: This was an observational cohort on incident end-stage kidney disease (ESKD) patients from January 1, 2007 to December 31, 2008. The primary outcome was all-cause mortality. Patients contributed person-time from the date of ESKD diagnosis until death, transplant or end of study on December 31, 2014, whichever occurred first. An extended Cox regression model with time-varying exposure to dialysis was used to account for immortal time bias. RESULTS: Of 3990 incident ESKD patients included, 70.2% patients initiated dialysis; 78.8% with haemodialysis (HD) while the remaining 21.2% with peritoneal dialysis (PD). Dialysis reduced hazard of death in both elderly and non-elderly patients even after controlling for comorbidities (hazard ratio [HR] 0.58, 95% confidence interval [CI] 0.50, 0.68 and HR 0.76, 95% CI 0.69, 0.85, respectively). HD was protective in both the elderly and non-elderly (HR 0.53, 95% CI 0.45, 0.63 and HR 0.71, 95% CI 0.64, 0.80, respectively). PD significantly reduced risk of death compared to no dialysis in the elderly but not in the non-elderly. CONCLUSION: Dialysis improved survival in all incident ESKD patients. The findings suggested a larger protection offered by HD. Although improvement in survival from initiating dialysis was large, its true benefit should take overall quality of life into account. SUMMARY AT A GLANCE This observational study showed that initiation of dialysis improves the survival of end-stage kidney disease (ESKD) patients of all age groups, but the quality of life is an important aspect that has not been explored.

Enhanced Near-Infrared-to-Visible Upconversion by Synthetic Control of PbS Nanocrystal Triplet Photosensitizers.

Photon upconversion employing semiconductor nanocrystals (NCs) makes use of their large and tunable absorption to harvest light in the near-infrared (NIR) wavelengths as well as their small gap between singlet and triplet excited states to reduce energy losses. Here, we report the highest QY (11.8%) thus far for the conversion of NIR to yellow photons by improving the quality of the PbS NC. This high QY was achieved by using highly purified lead and thiourea precursors. This QY is 2.6 times higher than from NCs prepared with commercially available lead and sulfide precursors. Transient absorption spectroscopy reveals two reasons for the enhanced QY: longer intrinsic exciton lifetimes of PbS NCs and the ability to support a longer triplet lifetime for the surface-bound transmitter molecule. Overall, this results in a higher efficiency of triplet exciton transfer from the PbS NC light absorber to the emitter and thus a higher photon upconversion QY.

Primary amines enhance triplet energy transfer from both the band edge and trap state from CdSe nanocrystals.

In this study, the role that primary amines play during triplet energy transfer from photoexcited CdSe nanocrystals (NCs) was examined. Colloidally synthesized CdSe NCs were placed in varying concentrations of 1-propyl- or 1-octylamine, with and without 2-anthracenecarboxylic acid transmitter ligands attached. This primary amine increases upconversion quantum yield approximately 5-fold. Further addition of amine does not improve photon upconversion, as CdSe NC photoluminescence (PL) increases at the expense of triplet energy transfer. Transient absorption measurements show that the amine plays three key roles. Primary amines enhance NC PL by decreasing the nonradiative decay rate, increase the rate of triplet energy transfer, and enable the broad trap state in these CdSe NCs to participate in triplet photosensitization.

Implication of Major Adverse Postoperative Events and Myocardial Injury on Disability and Survival: A Planned Subanalysis of the ENIGMA-II Trial.

BACKGROUND: Globally, >300 million patients have surgery annually, and ≤20% experience adverse postoperative events. We studied the impact of both cardiac and noncardiac adverse events on 1-year disability-free survival after noncardiac surgery. METHODS: We used the study cohort from the Evaluation of Nitrous oxide in Gas Mixture of Anesthesia (ENIGMA-II) trial, an international randomized trial of 6992 noncardiac surgical patients. All were ≥45 years of age and had moderate to high cardiac risk. The primary outcome was mortality within 1 postoperative year. We defined 4 separate types of postoperative adverse events. Major adverse cardiac events (MACEs) included myocardial infarction (MI), cardiac arrest, and myocardial revascularization with or without troponin elevation. MI was defined using the third Universal Definition and was blindly adjudicated. A second cohort consisted of patients with isolated troponin increases who did not meet the definition for MI. We also considered a cohort of patients who experienced major adverse postoperative events (MAPEs), including unplanned admission to intensive care, prolonged mechanical ventilation, wound infection, pulmonary embolism, and stroke. From this cohort, we identified a group without troponin elevation and another with troponin elevation that was not judged to be an MI. Multivariable Cox proportional hazard models for death at 1 year and assessments of proportionality of hazard functions were performed and expressed as an adjusted hazard ratio (aHR) and 95% confidence intervals (CIs). RESULTS: MACEs were observed in 469 patients, and another 754 patients had isolated troponin increases. MAPEs were observed in 631 patients. Compared with control patients, patients with a MACE were at increased risk of mortality (aHR, 3.36 [95% CI, 2.55-4.46]), similar to patients who suffered a MAPE without troponin elevation (n = 501) (aHR, 2.98 [95% CI, 2.26-3.92]). Patients who suffered a MAPE with troponin elevation but without MI had the highest risk of death (n = 116) (aHR, 4.29 [95% CI, 2.89-6.36]). These 4 types of adverse events similarly affected 1-year disability-free survival. CONCLUSIONS: MACEs and MAPEs occur at similar frequencies and affect survival to a similar degree. All 3 types of postoperative troponin elevation in this analysis were associated, to varying degrees, with increased risk of death and disability.

Stability of dobutamine in continuous ambulatory delivery devices.

WHAT IS KNOWN AND OBJECTIVE: Continuous infusion of dobutamine plays an important role in the management of patients with end-stage heart failure. Home infusion of dobutamine using a continuous ambulatory delivery device (CADD) facilitates the management of patients in their home, avoiding complications associated with long-term hospitalization. However, the stability of dobutamine in CADD is currently unknown. Therefore, this study investigated the physicochemical stability of dobutamine in CADDs at three different temperatures over various time points. METHODS: Six CADDs (three containing dobutamine 10 mg/mL in 0.9% sodium chloride and three containing dobutamine 10 mg/mL in 5% glucose) were prepared and stored at 4°C for 7 days, followed by 12 hours at 35°C and then for another 12 hours at 25°C. An aliquot (n = 3) was withdrawn aseptically at 0, 24, 48, 72, 96, 120, 144 and 168 hours when stored at 4°C, and at 0, 6 and 12 hours when stored at the other two temperatures. Each sample was analysed for dobutamine concentration using a stability-indicating high-performance liquid chromatography. All the samples were also evaluated for change in pH, colour and for particle content. RESULTS AND DISCUSSION: No evidence of particle formation, colour or pH change was observed throughout the study period. Dobutamine, when admixed with 0.9% sodium chloride or 5% glucose, was found to be chemically stable for at least 168 hours at 4°C and for another 12 hours at 35°C and for another 12 hours at 25°C. WHAT IS NEW AND CONCLUSIONS: Our findings will allow health professionals to provide a weekly supply of dobutamine-containing CADDs to patients for home infusions. Continuous infusion over a 24-hour period using one CADD per day will also decrease the number of exchanges required and thus reduce the risk of catheter-related bloodstream infections.

[Study on the negative regulation of TIPE2 from peripheral blood mononuclear cells on tissue factor in patients with bronchial asthma].

Objective: To investigate the expression of tumor necrosis factor alpha-inducible protein 8 like-2 (TIPE2) and tissue factor (TF) in patients with bronchial asthma. And to explore the regulation of TIPE2 on TF. Methods: Sixty-five asthmatic patients and 40 healthy controls were selected from the First Affiliated Hospital of Zhengzhou University from July to November, 2017. The expression of TIPE2 and TF in peripheral blood mononuclear cells of asthmatic patients and healthy controls were detected by Western blot.The level of TF protein in plasma was detected by enzyme-linked immunosorbent assay. The changes of TIPE2 and TF mRNA expression in THP-1 cells stimulated by house dust mite extract were detected by real-time fluorescence quantitative PCR (RT-PCR). The recombinant adenovirus Adv-TIPE2 was constructed and transfected into THP-1 cells and the effect of over-expression TIPE2 on TF expression in THP-1 cells was detected by RT-PCR. Results: The relative level of TIPE2 protein in asthmatic patients and healthy controls was 0.025±0.010 and 0.087±0.070, while that of TF was 0.40±0.27 and 0.15±0.10, respectively. Compared with healthy controls, the levels of TIPE2 protein decreased and TF protein increased in asthmatic patients, the differences were statistically significant (t=-5.06, 9.04, P<0.05) . TIPE2 protein level was negatively correlated with TF protein level (r=-0.460 3, P<0.05). The house dust mite extract reduced the expression level of TIPE2 mRNA in THP-1 cells, but increased the level of TF mRNA expression. When the concentration was 1 µg/ml, the change of TIPE2 mRNA was the most obvious at 4 h (P<0.05). The recombinant adenovirus Adv-TIPE2 was successfully constructed. The level of TF mRNA expression in THP-1 cells over-expressing TIPE2 gene was reduced (P<0.05). Conclusion: TIPE2, a negative regulator of inflammation, has a negative control effect on TF, and may be involved in the hyper-coagulable state of bronchial asthma by regulating TF expression.

Designing Transmitter Ligands That Mediate Energy Transfer between Semiconductor Nanocrystals and Molecules.

Molecular control of energy transfer is an attractive proposition because it allows chemists to synthetically tweak various kinetic and thermodynamic factors. In this Perspective, we examine energy transfer between semiconductor nanocrystals (NCs) and π-conjugated molecules, focusing on the transmitter ligand at the organic-inorganic interface. Efficient transfer of triplet excitons across this interface allows photons to be directed for effective use of the entire solar spectrum. For example, a photon upconversion system composed of semiconductor NCs as sensitizers, bound organic ligands as transmitters, and molecular annihilators has the advantage of large, tunable absorption cross sections across the visible and near-infrared wavelengths. This may allow the near-infrared photons to be harnessed for photovoltaics and photocatalysis. Here we summarize the progress in this recently reported hybrid upconversion platform and point out the challenges. Since triplet energy transfer (TET) from NC donors to molecular transmitters is one of the bottlenecks, emphasis is on the design of transmitters in terms of molecular energetics, photophysics, binding affinity, stability, and energy offsets with respect to the NC donor. Increasing the efficiency of TET in this hybrid platform will increase both the up- and down-conversion quantum yields, potentially exceeding the Shockley-Queisser limit for photovoltaics and photocatalysis.

Genetic diversity and phylogeographic structure of Bactrian camels shown by mitochondrial sequence variations.

The Bactrian camel includes various domestic (Camelus bactrianus) and wild (Camelus ferus) breeds that are important for transportation and for their nutritional value. However, there is a lack of extensive information on their genetic diversity and phylogeographic structure. Here, we studied these parameters by examining an 809-bp mtDNA fragment from 113 individuals, representing 11 domestic breeds, one wild breed and two hybrid individuals. We found 15 different haplotypes, and the phylogenetic analysis suggests that domestic and wild Bactrian camels have two distinct lineages. The analysis of molecular variance placed most of the genetic variance (90.14%, P < 0.01) between wild and domestic camel lineages, suggesting that domestic and wild Bactrian camel do not have the same maternal origin. The analysis of domestic Bactrian camels from different geographical locations found there was no significant genetic divergence in China, Russia and Mongolia. This suggests a strong gene flow due to wide movement of domestic Bactrian camels.

Androgen deprivation in LNCaP prostate tumour xenografts induces vascular changes and hypoxic stress, resulting in promotion of epithelial-to-mesenchymal transition.

BACKGROUND: When single-agent androgen deprivation therapy (ADT) is administered for locally advanced prostate cancer, men usually relapse within 1-2 years with more malignant castrate-resistant disease. The reason for this is currently unknown. We now hypothesise that an initial treatment response that increases tumour hypoxia drives selection of more malignant tumours. METHODS: The LNCaP prostate tumour xenografts were analysed for physiological (oxygen and vasculature) and genetic (PCR array) changes during longitudinal treatment with ADT (bicalutamide, 6 or 2 mg kg⁻¹ daily for 28 days). RESULTS: Bicalutamide caused an immediate (within 24 h) dose-dependent fall in oxygenation in LNCaP-luc prostate tumours with a nadir of ≤ 0.1% oxygen within 3-7 days; this was attributed to a significant loss of tumour microvessels (window chamber study). The hypoxic nadir persisted for 10-14 days. During the next 7 days, tumours regrew, oxygenation improved and the vasculature recovered; this was inhibited by the VEGF inhibitor B20.4.1.1. Gene expression over 28 days showed marked fluctuations consistent with the physiological changes. Accompanying the angiogenic burst (day 21) was a particularly striking increase in expression of genes associated with epithelial-to-mesenchymal transition (EMT). In particular, insulin-like growth factor 1 (IGF-1) showed increases in mRNA and protein expression. CONCLUSIONS: Hypoxic stress caused by ADT promotes EMT, providing a mechanism for the cause of malignant progression in prostate cancer.

Nitrite-driven anaerobic methane oxidation by oxygenic bacteria.

Only three biological pathways are known to produce oxygen: photosynthesis, chlorate respiration and the detoxification of reactive oxygen species. Here we present evidence for a fourth pathway, possibly of considerable geochemical and evolutionary importance. The pathway was discovered after metagenomic sequencing of an enrichment culture that couples anaerobic oxidation of methane with the reduction of nitrite to dinitrogen. The complete genome of the dominant bacterium, named 'Candidatus Methylomirabilis oxyfera', was assembled. This apparently anaerobic, denitrifying bacterium encoded, transcribed and expressed the well-established aerobic pathway for methane oxidation, whereas it lacked known genes for dinitrogen production. Subsequent isotopic labelling indicated that 'M. oxyfera' bypassed the denitrification intermediate nitrous oxide by the conversion of two nitric oxide molecules to dinitrogen and oxygen, which was used to oxidize methane. These results extend our understanding of hydrocarbon degradation under anoxic conditions and explain the biochemical mechanism of a poorly understood freshwater methane sink. Because nitrogen oxides were already present on early Earth, our finding opens up the possibility that oxygen was available to microbial metabolism before the evolution of oxygenic photosynthesis.

Molecular phylogeny of the Bactrian camel based on mitochondrial Cytochrome b gene sequences.

The Bactrian camel is an important domesticated animal providing milk, meat, and other products in desert countries. In this study, 111 individuals representing 11 domestic Bactrian camel breeds from China, Mongolia, Russia, and one wild Bactrian camel group from Mongolia were selected for the preparation of mitochondrial DNA. The 1140-bp fragments of the cytochrome b gene (Cytb) were amplified by polymerase chain reaction and sequenced directly. Sequences of the 92 domestic and 19 wild Bactrian camel samples were analyzed with DNASTAR, and a phylogenic tree was constructed using MEGA. The analysis revealed sixteen haplotypes among the samples that were divided into two haplogroups: a domestic haplogroup (H1-H13, H15, and H16) and a wild haplogroup (H14). Haplotype diversity values were from 0.356 in the HosZogdort, to 0.889 in the Sunit Bactrian camel breed. The Sunit breed displayed the highest nucleotide diversity value (0.00115), and the HosZogdort breed had the lowest value (0.00031). All domestic Bactrian camels formed a single monophyletic lineage that is the sister group to wild Bactrian camels, a finding consistent with a single domestication event and independent maternal inheritance since domestication. In addition, the most common mitochondrial haplotypes (H1, H3, and H4) were shared between Chinese, Mongolian, and Russian domestic Bactrian camels, which indicated that there was no distinguishing geographic structure among the domestic breeds from these three regions. These findings provide important insights into patterns of relatedness among Bactrian camels from the Chinese, Mongolian, and Russian regions.

Genetic diversity analysis of Croton antisyphiliticus Mart. using AFLP molecular markers.

Croton antisyphiliticus Mart. is a medicinal plant native to Cerrado vegetation in Brazil, and it is popularly used to treat urogenital tract infections. The objective of the present study was to assess the genetic variability of natural C. antisyphiliticus populations using AFLP molecular markers. Accessions were collected in the states of Minas Gerais, São Paulo, and Goiás. The genotyping of individuals was performed using a LI-COR® DNA Analyzer 4300. The variability within populations was found to be greater than the variability between them. The F(ST) value was 0.3830, which indicated that the populations were highly structured. A higher percentage of polymorphic loci (92.16%) and greater genetic diversity were found in the population accessions from Pratinha-MG. Gene flow was considered restricted (N(m) = 1.18), and there was no correlation between genetic and geographic distances. The populations of C. antisyphiliticus exhibited an island-model structure, which demonstrates the vulnerability of the species.

Predictive Soft Tissue Airway Volume Analysis in Mandibular Distraction: Pushing The Envelope in Surgical Planning for Obstructive Sleep Apnea.

Three-dimensional computed tomography has been used in both preoperative planning of mandibular distraction osteogenesis and in the evaluation of postoperative resolution of tongue-based airway obstruction. The authors present a case report using software to predict postdistraction airway volume during virtual surgical planning (VSP) of mandibular distraction osteogenesis in a 7 year old. The predicted increase in airway volume derived from VSP was 33.57% (1716 mm(3) preoperatively to 2292 mm(3) postvirtual distraction). Based on the three-dimensional computed tomography, the actual airway volume increased to 2211 mm(3) postoperatively, a 28.85% increase.The implications of this advancing technology are far-reaching. An illustrative case is presented herein to demonstrate the efficacy of the airway prediction and its limitations. The authors believe that, with continued investigation, this novel approach may be a standard feature of all VSP sessions for the treatment of tongue-based airway obstruction.

Hybrid Molecule-Nanocrystal Photon Upconversion Across the Visible and Near-Infrared.

The ability to upconvert two low energy photons into one high energy photon has potential applications in solar energy, biological imaging, and data storage. In this Letter, CdSe and PbSe semiconductor nanocrystals are combined with molecular emitters (diphenylanthracene and rubrene) to upconvert photons in both the visible and the near-infrared spectral regions. Absorption of low energy photons by the nanocrystals is followed by energy transfer to the molecular triplet states, which then undergo triplet-triplet annihilation to create high energy singlet states that emit upconverted light. By using conjugated organic ligands on the CdSe nanocrystals to form an energy cascade, the upconversion process could be enhanced by up to 3 orders of magnitude. The use of different combinations of nanocrystals and emitters shows that this platform has great flexibility in the choice of both excitation and emission wavelengths.

XoxF-type methanol dehydrogenase from the anaerobic methanotroph "Candidatus Methylomirabilis oxyfera".

"Candidatus Methylomirabilis oxyfera" is a newly discovered anaerobic methanotroph that, surprisingly, oxidizes methane through an aerobic methane oxidation pathway. The second step in this aerobic pathway is the oxidation of methanol. In Gramnegative bacteria, the reaction is catalyzed by pyrroloquinoline quinone (PQQ)-dependent methanol dehydrogenase (MDH). The genome of "Ca. Methylomirabilis oxyfera" putatively encodes three different MDHs that are localized in one large gene cluster: one so-called MxaFI-type MDH and two XoxF-type MDHs (XoxF1 and XoxF2). MxaFI MDHs represent the canonical enzymes, which are composed of two PQQ-containing large (α) subunits (MxaF) and two small (ß) subunits (MxaI). XoxF MDHs are novel, ecologically widespread, but poorly investigated types of MDHs that can be phylogenetically divided into at least five different clades. The XoxF MDHs described thus far are homodimeric proteins containing a large subunit only. Here, we purified a heterotetrameric MDH from "Ca. Methylomirabilis oxyfera" that consisted of two XoxF and two MxaI subunits. The enzyme was localized in the periplasm of "Ca. Methylomirabilis oxyfera" cells and catalyzed methanol oxidation with appreciable specific activity and affinity (Vmax of 10 micromole min(-1) mg(-1) protein, Km of 17 microM). PQQ was present as the prosthetic group,which has to be taken up from the environment since the known gene inventory required for the synthesis of this cofactor is lacking. The MDH from "Ca. Methylomirabilis oxyfera" is the first representative of type 1 XoxF proteins to be described.