Noncentrosymmetric conductors are an interesting material platform, with rich spintronic functionalities and exotic superconducting properties typically produced in polar systems with Rashba-type ...spin-orbit interactions. Polar conductors should also exhibit inherent nonreciprocal transport, in which the rightward and leftward currents differ from each other. But such a rectification is difficult to achieve in bulk materials because, unlike the translationally asymmetric p-n junctions, bulk materials are translationally symmetric, making this phenomenon highly nontrivial. Here we report a bulk rectification effect in a three-dimensional Rashba-type polar semiconductor BiTeBr. Experimentally observed nonreciprocal electric signals are quantitatively explained by theoretical calculations based on the Boltzmann equation considering the giant Rashba spin-orbit coupling. The present result offers a microscopic understanding of the bulk rectification effect intrinsic to polar conductors as well as a simple electrical means to estimate the spin-orbit parameter in a variety of noncentrosymmetric systems.
Programmed cell death (PCD) is one of the important terminal paths for the cells of metazoans, and is involved in a variety of biological events that include morphogenesis, maintenance of tissue ...homeostasis, and elimination of harmful cells. Dysfunction of PCD leads to various diseases in humans, including cancer and several degenerative diseases. Apoptosis is not the only form of PCD. Recent studies have provided evidence that there is another mechanism of PCD, which is associated with the appearance of autophagosomes and depends on autophagy proteins. This form of cell death most likely corresponds to a process that has been morphologically defined as autophagic PCD. The present review summarizes recent experimental evidence about autophagic PCD and discusses some aspects of this form of cell death, including the mechanisms that may distinguish autophagic death from the process of autophagy involved in cell survival.
Conspectus This Account highlights the work from our laboratories on bis-urea macrocycles constructed from two C-shaped spacers and two urea groups. These simple molecular units assembled with high ...fidelity into columnar structures guided by the three-centered urea hydrogen bonding motif and aryl stacking interactions. Individual columns are aligned and closely packed together to afford functional and homogeneous microporous crystals. This approach allows for precise and rational control over the dimensions of the columnar structure simply by changing the small molecular unit. When the macrocyclic unit lacks a cavity, columnar assembly gives strong pillars. Strong pillars with external functional groups such as basic lone pairs can expand like clays to accept guests between the pillars. Macrocycles that contain sizable interior cavities assemble into porous molecular crystals with aligned, well-defined columnar pores that are accessible to gases and guests. Herein, we examine the optimal design of the macrocyclic unit that leads to columnar assembly in high fidelity and probe the feasibility of incorporating a second functional group within the macrocycles. The porous molecular crystals prepared through the self-assembly of bis-urea macrocycles display surface areas similar to zeolites but lower than MOFs. Their simple one-dimensional channels are well-suited for studying binding, investigating transport, diffusion and exchange, and monitoring the effects of encapsulation on reaction mechanism and product distribution. Guests that complement the size, shape, and polarity of the channels can be absorbed into these porous crystals with repeatable stoichiometry to form solid host–guest complexes. Heating or extraction with an organic solvent enables desorption or removal of the guest and subsequent recovery of the solid host. Further, these porous crystals can be used as containers for the selective 2 + 2 cycloadditions of small enones such as 2-cyclohexenone or 3-methyl-cyclopentenone, while larger hosts bind and facilitate the photodimerization of coumarin. When the host framework incorporates benzophenone, a triplet sensitizer, UV-irradiation in the presence of oxygen efficiently generates singlet oxygen. Complexes of this host were employed to influence the selectivity of photooxidations of 2-methyl-2-butene and cumene with singlet oxygen. Small systematic changes in the channel and bound reactants should enable systematic evaluation of the effects of channel dimensions, guest dimensions, and channel–guest interactions on the processes of absorption, diffusion, and reaction of guests within these nanochannels. Such studies could help in the development of new materials for separations, gas storage, and catalysis.
The threshold of intraoperative urine output below which the risk of acute kidney injury (AKI) increases is unclear. The aim of this retrospective cohort study was to investigate the relationship ...between intraoperative urine output during major abdominal surgery and the development of postoperative AKI and to identify an optimal threshold for predicting the differential risk of AKI.
Perioperative data were collected retrospectively on 3560 patients undergoing major abdominal surgery (liver, colorectal, gastric, pancreatic, or oesophageal resection) at Kyoto University Hospital. We evaluated the relationship between intraoperative urine output and the development of postoperative AKI as defined by recent guidelines. Logistic regression analysis was performed to adjust for patient and operative variables, and the minimum P-value approach was used to determine the threshold of intraoperative urine output that independently altered the risk of AKI.
The overall incidence of AKI in the study population was 6.3%. Using the minimum P-value approach, a threshold of 0.3 ml kg−1 h−1 was identified, below which there was an increased risk of AKI (adjusted odds ratio, 2.65; 95% confidence interval, 1.77–3.97; P<0.001). The addition of oliguria <0.3 ml kg−1 h−1 to a model with conventional risk factors significantly improved risk stratification for AKI (net reclassification improvement, 0.159; 95% confidence interval, 0.049–0.270; P=0.005).
Among patients undergoing major abdominal surgery, intraoperative oliguria <0.3 ml kg−1 h−1 was significantly associated with increased risk of postoperative AKI.
Summary
Helicobacter cinaedi is an emerging Gram‐negative spiral bacillus that was first reported in 1984. It has been implicated as a cause of gastroenteritis and bacteraemia in immunocompromised ...individuals. Helicobacter cinaedi‐associated bacteraemia is sometimes accompanied by skin lesions; however, the cutaneous manifestations of this pathogen are not widely known. To our knowledge, a comprehensive review with detailed analysis of skin lesions associated with H. cinaedi has not been conducted. This article summarizes the clinical appearance of H. cinaedi cellulitis and its management. In addition, we conducted a retrospective review of 73 patients with H. cinaedi bacteraemia at a single institution, to further clarify the characteristic cutaneous features. It was found that 30% (22/73) of the cases of H. cinaedi bacteraemia had sudden‐onset erythema accompanied by high fever. The most common cutaneous symptom of H. cinaedi bacteraemia was found to be mild cellulitis, appearing as multiple painful infiltrated erythemas on the extremities. As H. cinaedi is not always detectable in routine blood culture techniques, evaluation of these characteristic cutaneous manifestations seems important in diagnosis. Helicobacter cinaedi infection should be added to the diagnostic list of unspecified fever with painful infiltrated erythemas.
What's already known about this topic?
Helicobacter cinaedi causes bacteraemia and cellulitis in immunodeficient individuals; however, details of the cutaneous manifestations and their management are not fully described.
What does this study add?
The cutaneous manifestations, epidemiology and management of H. cinaedi infection are described in detail. Helicobacter cinaedi cellulitis, which appears as multiple painful infiltrated erythemas on the extremities, is the most common cutaneous symptom of H. cinaedi bacteraemia.
Linked Comment: Laftah and Hay. Br J Dermatol 2016; 175:13–14
Soil is likely the most complex ecosystem on earth. Despite the global importance and extraordinary diversity of soils, they have been notoriously challenging to study. We show how pioneering ...microfluidic techniques provide new ways of studying soil microbial ecology by allowing simulation and manipulation of chemical conditions and physical structures at the microscale in soil model habitats.
The microstructures of Al alloy 6061 subjected to very-high-power ultrasonic additive manufacturing were systematically examined to understand the underlying ultrasonic welding mechanism. The ...microstructure of the weld interface between the metal tapes consisted of fine, equiaxed grains resulting from recrystallization, which is driven by simple shear deformation along the ultrasonically vibrating direction of the tape surface. Void formation at the weld interface is attributed to surface asperities resulting from pressure induced by the sonotrode at the initial tape deposition. Transmission electron microscopy revealed that Al–Al metallic bonding without surface oxide layers was mainly achieved, although some oxide clusters were locally observed at the original interface. The results suggest that the oxide layers were broken up and then locally clustered on the interface by ultrasonic vibration.
In their natural environment, cells need to extract useful information from complex temporal signals that vary over a wide range of intensities and time scales. Here, we study how such signals are ...processed by Escherichia coli during chemotaxis by developing a general theoretical model based on receptor adaptation and receptor-receptor cooperativity. Measured responses to various monotonic, oscillatory, and impulsive stimuli are all explained consistently by the underlying adaptation kinetics within this model. For exponential ramp signals, an analytical solution is discovered that reveals a remarkable connection between the dependence of kinase activity on the exponential ramp rate and the receptor methylation rate function. For exponentiated sine-wave signals, spectral analysis shows that the chemotaxis pathway acts as a lowpass filter for the derivative of the signal with the cutoff frequency determined by an intrinsic adaptation time scale. For large step stimuli, we find that the recovery time is determined by the constant maximum methylation rate, which provides a natural explanation for the observed recovery time additivity. Our model provides a quantitative system-level description of the chemotaxis signaling pathway and can be used to predict E. coli chemotaxis responses to arbitrary temporal signals. This model of the receptor system reveals the molecular origin of Weber's law in bacterial chemotaxis. We further identify additional constraints required to account for the related observation that the output of this pathway is constant under exponential ramp stimuli, a feature that we call "logarithmic tracking."
The formation of the Ontong Java Nui super oceanic plateau (OJN), which is based on the model that the submarine Ontong Java Plateau (OJP), Manihiki Plateau (MP), and Hikurangi Plateau (HP) were once ...its contiguous fragments, could have been the largest globally consequential volcanic event in Earth's history. This OJN hypothesis has been debated given the paucity of evidence, for example, the differences in crustal thickness, the compositional gap between MP and OJP basalts and the apparent older age of both plateaus relative to HP remain unresolved. Here we investigate the geochemical and
Ar-
Ar ages of dredged rocks recovered from the OJP's eastern margin. Volcanic rocks having compositions that match the low-Ti MP basalts are reported for the first time on the OJP and new ~ 96-116 Ma and 67-68 Ma
Ar-
Ar age data bridge the temporal gap between OJP and HP. These results provide new evidence for the Ontong Java Nui hypothesis and a framework for an integrated tectonomagmatic evolution of the OJP, MP, and HP. The isotopic data imply four mantle components in the source of OJN that are also expressed in present-day Pacific hotspots sources, indicating origin from (and longevity of) the Pacific Large Low Shear-wave Velocity Province.
Diffusion-based microfluidic devices can generate steady, arbitrarily shaped chemical gradients without requiring fluid flow and are ideal for studying chemotaxis of free-swimming cells such as ...bacteria. However, if microfluidic gradient generators are to be used to systematically study bacterial chemotaxis, it is critical to evaluate their performance with actual quantitative chemotaxis tests. We characterize and compare three diffusion-based gradient generators by confocal microscopy and numerical simulations, select an optimal design and apply it to chemotaxis experiments with Escherichia coli in both linear and nonlinear gradients. Comparison of the observed cell distribution along the gradients with predictions from an established mathematical model shows very good agreement, providing the first quantification of chemotaxis of free-swimming cells in steady nonlinear microfluidic gradients and opening the door to bacterial chemotaxis studies in gradients of arbitrary shape.
PDF
