The Single-Pitch Texel: A flexible and practical texture-rendering algorithm.

As the number of applications for tactile feedback technology rapidly increases, so too does the need for efficient, flexible, and extensible representations of virtual textures. The previously introduced Single-Pitch Texel rendering algorithm offers designers the ability to produce textures with perceptually wide-band spectral characteristics while requiring very few input parameters. This paper expands on the capabilities of the rendering algorithm. Diverse families of fine textures, with widely varied spectral characteristics, were shown to be rendered reliably using the Texel algorithm. Furthermore, by leveraging an assistive algorithm, subjects were shown to consistently navigate the Texel parameter space in a matching task. Finally, a psychophysical study was conducted to demonstrate the rendering algorithm's resilience to spectral quantization, further reducing the data required to represent a virtual texture.

Chemical Sulfide Tethering Improves Low-Temperature Li-S Battery Cycling.

Demands for energy storage and delivery continue to rise worldwide, making it imperative that reliable performance is achievable in diverse climates. Lithium-sulfur (Li-S) batteries offer a promising alternative to lithium-ion batteries owing to their substantially higher specific capacity and energy density. However, improvements to Li-S systems are still needed in low-temperature environments where polysulfide clustering and solubility limitations prohibit complete charge/discharge cycles. We address these issues by introducing thiophosphate-functionalized metal-organic frameworks (MOFs), capable of tethering polysulfides, into the cathode architecture. Compared to cells with the parent MOFs, cells containing the functionalized MOFs exhibit greater capacity delivery and decreased polarization for a range of temperatures down to -10 °C. We conduct thorough electrochemical analyses to ascertain the origins of performance differences and report an altered Li-S redox mechanism enabled by the thiophosphate moiety. This investigation is the first low-temperature Li-S study using MOF additives and represents a promising direction in enabling energy storage in extreme environments.

Graphene-Metal-Organic Framework Composite Sulfur Electrodes for Li-S Batteries with High Volumetric Capacity.

In an age of rapid acceleration toward next-generation energy storage technologies, lithium-sulfur (Li-S) batteries offer the desirable combination of low weight and high specific energy. Metal-organic frameworks (MOFs) have been recently studied as functionalizable platforms to improve Li-S battery performance. However, many MOF-enabled Li-S technologies are hindered by low capacity retention and poor long-term performance due to low electronic conductivity. In this work, we combine the advantages of a Zr-based MOF-808 loaded with sulfur as the active material with a graphene/ethyl cellulose additive, leading to a high-density nanocomposite electrode requiring minimal carbon. Our electrochemical results indicate that the nanocomposites deliver enhanced specific capacity over conventionally used carbon/binder mixtures, and postsynthetic modification of the MOF with lithium thiophosphate results in further improvement. Furthermore, the dense form factor of the sulfur-loaded MOF-graphene nanocomposite electrodes provides high volumetric capacity compared to other works with significantly more carbon additives. Overall, we have demonstrated a proof-of-concept paradigm where graphene nanosheets facilitate improved charge transport because of enhanced interfacial contact with the active material. This materials engineering approach can likely be extended to other MOF systems, contributing to an emerging class of two-dimensional nanomaterial-enabled Li-S batteries.

2D Oligosilyl Metal-Organic Frameworks as Multi-state Switchable Materials.

We report the synthesis of a set of 2D metal-organic frameworks (MOFs) constructed with organosilicon-based linkers. These oligosilyl MOFs feature linear Sin Me2n (C6 H4 CO2 H)2 ligands (lin-Sin , n=2, 4) connected by Cu paddlewheels. The stacking arrangement of the 2D sheets is dictated by van der Waals interactions and is tunable by solvent exchange, leading to reversible structural transformations between many crystalline and amorphous phases.

Lithiated Defect Sites in Zr Metal-Organic Framework for Enhanced Sulfur Utilization in Li-S Batteries.

Lithium sulfur (Li-S) battery technology is one of the most promising candidates for next-generation energy storage devices; however, it is still hindered by limited capacity yield and poor long-term stability. The complexity of these devices has hindered efforts to study electrochemical determinants of battery performance, impeding advancement of the field. Due to the ease of functionalization, metal-organic frameworks (MOFs) are unique platforms to explore such reactions, where integration of defects into the crystalline structure provides a convenient method for introducing synthetic handles. In Zr-based MOFs such as UiO-66, the engineered defect sites contain acidic protons that can be replaced with lithium ions, transforming defected MOFs into a range of materials with tunable lithium content. Our results demonstrate the capability of this facile lithiation procedure to create novel cathode additives and evaluate their influence on Li-S battery performance. By improving ionic conductivity and dispersion of sulfur species, lithiated MOFs enhance both sulfur utilization and capacity retention at a variety of cycling rates compared to the as-synthesized MOFs. Our general synthetic strategy has the potential to be applied to technologies beyond MOFs, including polymeric and inorganic materials. Ultimately, we illustrate that defected MOFs can be used to systematically control lithiation, currently unprecedented in conventional inorganic materials, and provide a window to examine heterogeneous reactions relevant to energy conversion and storage.

Diversity of Clostridium difficile PCR ribotypes in Europe: results from the European, multicentre, prospective, biannual, point-prevalence study of Clostridium difficile infection in hospitalised patients with diarrhoea (EUCLID), 2012 and 2013.

Clostridium difficile infection (CDI) is the major cause of infective diarrhoea in healthcare environments. As part of the European, multicentre, prospective, biannual, point-prevalence study of Clostridium difficile infection in hospitalised patients with diarrhoea (EUCLID), the largest C. difficile epidemiological study of its type, PCR ribotype distribution of C. difficile isolates in Europe was investigated. PCR ribotyping was performed on 1,196 C. difficile isolates from diarrhoeal samples sent to the European coordinating laboratory in 2012-13 and 2013 (from two sampling days) by 482 participating hospitals from 19 European countries. A total of 125 ribotypes were identified, of which ribotypes 027 (19%, n =222), 001/072 (11%, n = 134) and 014/020 (10%, n = 119) were the most prevalent. Distinct regional patterns of ribotype distribution were noted. Of 596 isolates from patients with toxin-positive stools (CDI cases), ribotype 027 accounted for 22% (32/144) of infections in cases aged from 18 to less than 65 years, but the prevalence decreased in those aged ≥ 65 years (14% (59/412)) and further decreased in those aged ≥ 81 years (9% (18/195)). The prevalence of ribotype 027 and 176, but not other epidemic strains, was inversely proportional to overall ribotype diversity (R(2) = 0.717). This study highlights an increased diversity of C. difficile ribotypes across Europe compared with previous studies, with considerable intercountry variation in ribotype distribution. Continuous surveillance programmes are necessary to monitor the changing epidemiology of C. difficile.

State-Specific Collision Dynamics of Molecular Super Rotors with Oriented Angular Momentum.

An optical centrifuge pulse drives carbon dioxide molecules into ultrahigh rotational states with rotational frequencies of ω ≈ 32 THz based on the centrifuge frequency at the full width at half-maximum of the spectral chirp. High-resolution transient IR absorption spectroscopy is used to measure the time-evolution of translational and rotational energy for a number of states in the range of J = 0-100 at a sample pressure of 5-10 Torr. Transient Doppler profiles show that the products of super rotor collisions contain substantial amounts of translational energy, with J-dependent energies correlating to a range of ΔJ propensities. The transient population in J = 100 is short-lived, indicating rapid relaxation of high J states; populations in J = 36, 54, and 76 increase overall as the super rotor energy is redistributed. Transient line profiles for J = 0 and 36 are consistently narrower than the initial ambient sample temperature, showing that collision cross sections for super rotors increase with decreasing collision energy. Quantum scattering calculations on Ar-CO2(j) collisions are used to interpret the qualitative features of the experimental results. The results of this study provide the groundwork for developing a more complete understanding of super rotor dynamics.

Lung disease with anti-CCP antibodies but not rheumatoid arthritis or connective tissue disease.

OBJECTIVE: We sought to characterize a novel cohort of patients with lung disease, anti-cyclic citrullinated peptide (CCP) antibody positivity, without rheumatoid arthritis (RA) or other connective tissue disease (CTD). METHODS: The study sample included 74 subjects with respiratory symptoms, evaluated January 2008-January 2010 and found to have a positive anti-CCP antibody but no evidence for RA or other CTD. Each underwent serologic testing, pulmonary physiology testing, and thoracic high-resolution computed tomography (HRCT) scan as part of routine clinical evaluation. RESULTS: The majority of subjects were women, and most were former cigarette smokers. Four distinct radiographic phenotypes were identified: isolated airways disease (54%), isolated interstitial lung disease (ILD) (14%), mixed airways disease and ILD (26%), and combined pulmonary fibrosis with emphysema (7%). This cohort had a predominance of airways disease, either in isolation or along with a usual interstitial pneumonia-pattern of ILD. Among subjects with high-titer anti-CCP positivity (n=33), three developed the articular manifestations of RA during a median follow-up of 449 days. CONCLUSION: We have described a unique cohort of patients with anti-CCP antibody positivity and lung disease in the absence of existing RA or other CTD. The lung phenotypic characteristics of this cohort resemble those of established RA and a few of these patients have developed articular RA within a short period of follow-up. The implications of a positive anti-CCP antibody among patients with lung disease but not RA are not yet known, but we believe requires further investigation.

Spores of Clostridium difficile clinical isolates display a diverse germination response to bile salts.

Clostridium difficile spores play a pivotal role in the transmission of infectious diarrhoea, but in order to cause disease spores must complete germination and return to vegetative cell growth. While the mechanisms of spore germination are well understood in Bacillus, knowledge of C. difficile germination remains limited. Previous studies have shown that bile salts and amino acids play an important role in regulating the germination response of C. difficile spores. Taurocholate, in combination with glycine, can stimulate germination, whereas chenodeoxycholate has been shown to inhibit spore germination in a C. difficile clinical isolate. Our recent studies of C. difficile sporulation characteristics have since pointed to substantial diversity among different clinical isolates. Consequently, in this study we investigated how the germination characteristics of different C. difficile isolates vary in response to bile salts. By analysing 29 isolates, including 16 belonging to the BI/NAP1/027 type, we show that considerable diversity exists in both the rate and extent of C. difficile germination in response to rich medium containing both taurocholate and glycine. Strikingly, we also show that although a potent inhibitor of germination for some isolates, chenodeoxycholate does not inhibit the germination, or outgrowth, of all C. difficile strains. Finally, we provide evidence that components of rich media may induce the germination of C. difficile spores, even in the absence of taurocholate. Taken together, these data suggest that the mechanisms of C. difficile spore germination in response to bile salts are complex and require further study. Furthermore, we stress the importance of studying multiple isolates in the future when analysing the nutrients or chemicals that either stimulate or inhibit C. difficile spore germination.

Reconsidering the sporulation characteristics of hypervirulent Clostridium difficile BI/NAP1/027.

Clostridium difficile is the leading cause of antibiotic-associated diarrhoea and a major burden to healthcare services worldwide. In recent years, C. difficile strains belonging to the BI/NAP1/027 type have become highly represented among clinical isolates. These so-called 'hypervirulent' strains are associated with outbreaks of increased disease severity, higher relapse rates and an expanded repertoire of antibiotic resistance. Spores, formed during sporulation, play a pivotal role in disease transmission and it has been suggested that BI/NAP1/027 strains are more prolific in terms of sporulation in vitro than 'non-epidemic' C. difficile types. Work in our laboratory has since provided credible evidence to the contrary suggesting that the strain-to-strain variation in C. difficile sporulation characteristics is not type-associated. However, the BI/NAP1/027 type is still widely stated to have an increased rate of sporulation. In this study, we analysed the sporulation rates of 53 C. difficile strains, the largest sample size used to-date in such a study, including 28 BI/NAP1/027 isolates. Our data confirm that significant variation exists in the rate at which different C. difficile strains form spores. However, we clearly show that the sporulation rate of the BI/NAP1/027 type was no higher than that of non-BI/NAP1/027 strains. In addition, we observed substantial variation in sporulation characteristics within the BI/NAP1/027 type. This work highlights the danger of assuming that all strains of one type behave similarly without studying adequate sample sizes. Furthermore, we stress the need for more rigorous experimental procedures in order to quantify C. difficile sporulation more accurately in the future.

Sporulation studies in Clostridium difficile.

Clostridium difficile is a leading cause of healthcare-associated diarrhoea. In recent years, certain C. difficile types have become highly represented among clinical isolates and are associated with outbreaks of increased disease severity, higher relapse rates and an expanded repertoire of antibiotic resistance. Endospores, produced during sporulation, play a pivotal role in infection and disease transmission and it has been suggested in the literature that these so-called 'hypervirulent' C. difficile types are more prolific in terms of sporulation in vitro. However, work in our laboratory has provided evidence to the contrary suggesting that although there is significant strain-to-strain variation in C. difficile sporulation characteristics this variation does not appear to be type-associated. On analysis of the literature, it is apparent that the methods used to quantify sporulation in previous studies have varied greatly and sample sizes have remained small. The conflicting data in the literature may, therefore, not necessarily be generally representative of C. difficile sporulation. Instead, these inconsistencies may reflect differences in the experimental design of each study. In this review, the need for further investigations of C. difficile sporulation rates is highlighted. Specifically, the advantages and disadvantages of the different experimental approaches previously used are discussed and a standard set of principles for measuring C. difficile sporulation in the future is proposed.

The diverse sporulation characteristics of Clostridium difficile clinical isolates are not associated with type.

Clostridium difficile causes diarrhoeal diseases ranging from asymptomatic carriage to a fulminant, relapsing, and potentially fatal colitis. Endospore production plays a vital role in transmission of infection, and in order to cause disease these spores must then germinate and return to vegetative cell growth. Type BI/NAP1/027 strains of C. difficile have recently become highly represented among clinical isolates and are associated with increased disease severity. It has also been suggested that these 'epidemic' types generally sporulate more prolifically than 'non-epidemic' strains, although the few existing reports are inconclusive and encompass only a small number of isolates. In order to better understand any differences in sporulation rates between epidemic and non-epidemic C. difficile types, we analysed these characteristics using 14 C. difficile clinical isolates of a variety of types. Sporulation rates varied greatly between individual BI/NAP1/027 isolates, but this variation did not appear to be type-associated. Furthermore, a number of BI/NAP1/027 spores appeared to form colonies with a lower frequency than specific non-BI/NAP1/027 strains. The data suggest that (i) careful experimental design is required in order to accurately quantify sporulation; and (ii) current evidence cannot link differences in sporulation rates with the disease severity of the BI/NAP1/027 type.

Clostridium difficile spore germination: an update.

Endospore production is vital for the spread of Clostridium difficile infection. However, in order to cause disease, these spores must germinate and return to vegetative cell growth. Knowledge of germination is therefore important, with potential practical implications for routine cleaning, outbreak management and potentially in the design of new therapeutics. Germination has been well studied in Bacillus, but until recently there had been few studies reported in C. difficile. The role of bile salts as germinants for C. difficile spores has now been described in some detail, which improves our understanding of how C. difficile spores interact with their environment following ingestion by susceptible individuals. Furthermore, with the aid of novel genetic tools, it has now become possible to study the germination of C. difficile spores using both a forward and reverse genetics approach. Significant progress is beginning to be made in the study of this important aspect of C. difficile disease.

SleC is essential for germination of Clostridium difficile spores in nutrient-rich medium supplemented with the bile salt taurocholate.

Clostridium difficile is the major cause of infectious diarrhea and a major burden to health care services. The ability of this organism to form endospores plays a pivotal role in infection and disease transmission. Spores are highly resistant to many forms of disinfection and thus are able to persist on hospital surfaces and disseminate infection. In order to cause disease, the spores must germinate and the organism must grow vegetatively. Spore germination in Bacillus is well understood, and genes important for this process have recently been identified in Clostridium perfringens; however, little is known about C. difficile. Apparent homologues of the spore cortex lytic enzyme genes cwlJ and sleB (Bacillus subtilis) and sleC (C. perfringens) are present in the C. difficile genome, and we describe inactivation of these homologues in C. difficile 630Delta erm and a B1/NAP1/027 clinical isolate. Spores of a sleC mutant were unable to form colonies when germination was induced with taurocholate, although decoated sleC spores formed the same number of heat-resistant colonies as the parental control, even in the absence of germinants. This suggests that sleC is absolutely required for conversion of spores to vegetative cells, in contrast to CD3563 (a cwlJ/sleB homologue), inactivation of which had no effect on germination and outgrowth of C. difficile spores under the same conditions. The B1/NAP1/027 strain R20291 was found to sporulate more slowly and produce fewer spores than 630Delta erm. Furthermore, fewer R20291 spores germinated, indicating that there are differences in both sporulation and germination between these epidemic and nonepidemic C. difficile isolates.

Intercostally placed paravertebral catheterization: an alternative approach to continuous paravertebral blockade.

BACKGROUND: Continuous paravertebral nerve blocks can provide effective postoperative analgesia after abdominal and thoracic surgery. While offering a number of advantages compared with thoracic epidural analgesia, access to the paravertebral space using a classic approach is not always easily accomplished and/or possible. In this regard, continuous paravertebral blockade via a percutaneous intercostal approach may theoretically serve as an alternative approach to the paravertebral space. METHODS: One hundred ten patients undergoing major abdominal, thoracic, or retroperitoneal procedures had preoperative placement of unilateral or bilateral paravertebral catheter(s) via an intercostal approach. At a point 8 cm lateral to the midline a 5 cm, 18 G Tuohy needle was advanced with the needle tip angled 45 degrees cephalad and 60 degrees medial to the sagittal plane to come in contact with the lower third of the rib. The needle was "walked-off" the inferior border of the rib while maintaining its orientation and advanced a further 5 to 6 mm under the rib to lie in the subcostal groove. After injection of 5 mL ropivacaine 0.5%, a catheter was advanced medially the estimated distance to the paravertebral space. Postoperatively 0.2% ropivacaine was continuously infused at 10 mL/h in each catheter with hourly boluses of 5 mL available for breakthrough pain. RESULTS: Median pain scores averaged 2 on a scale of 0-10 and patient-controlled analgesia hydromorphone consumption averaged only 1.69 mg for the first 24 h postoperatively. There were no clinically significant complications of the technique. CONCLUSION: The intercostally placed paravertebral catheter provides postoperative analgesia after major surgery of the chest, abdomen, or retroperitoneum.