Room-temperature quantum emission from interface excitons in mixed-dimensional heterostructures

The development of van der Waals heterostructures has introduced unconventional phenomena that emerge at atomically precise interfaces. For example, interlayer excitons in two-dimensional transition metal dichalcogenides show intriguing optical properties at low temperatures. Here we report on room-temperature observation of interface excitons in mixed-dimensional heterostructures consisting of two-dimensional tungsten diselenide and one-dimensional carbon nanotubes. Bright emission peaks originating from the interface are identified, spanning a broad energy range within the telecommunication wavelengths. The effect of band alignment is investigated by systematically varying the nanotube bandgap, and we assign the new peaks to interface excitons as they only appear in type-II heterostructures. Room-temperature localization of low-energy interface excitons is indicated by extended lifetimes as well as small excitation saturation powers, and photon correlation measurements confirm antibunching. With mixed-dimensional van der Waals heterostructures where band alignment can be engineered, new opportunities for quantum photonics are envisioned.

Inhibition of P21-activated Kinase 1 Promotes Vascular Smooth Muscle Cells Apoptosis Through Reduction of Phosphorylation of Bad

BACKGROUND

P21-activated kinase 1 (Pak1) has an effect on cell apoptosis and has recently been reported to play an important role in various cardiovascular diseases, in which vascular smooth muscle cell (VSMC) apoptosis is a key process. Thus, we hypothesized that Pak1 may be a novel target to regulate VSMC behaviors.

METHODS AND RESULTS

In the present study, we found that the expression of Pak1 was dramatically upregulated in vascular smooth muscle cells (VSMCs) on H2O2 administration and was dependent on stimulation time. Through a loss-of-function approach, Pak1 knockdown increased apoptosis of VSMCs, as tested by TUNEL (TdT-mediated dUTP Nick-End Labeling) immunofluorescence staining, whereas it inhibited the proliferation of VSMCs examined by EdU staining. Moreover, we also noticed that Pak1 silencing promoted the mRNA and protein levels of pro-apoptosis genes but decreased anti-apoptosis marker expression. Importantly, we showed that Pak1 knockdown reduced the phosphorylation of Bad. Moreover, increased Pak1 expression was also noticed in carotid arteries on the wire jury.

CONCLUSIONS

Our study identified that Pak1 acted as a novel regulator of apoptosis of VSMCs partially through phosphorylation of Bad.

[Surface morphology and surface properties of Ti and TiZr implant materials]

Objective: To investigate the effects of hydrophilic treatment on the surface morphology and surface properties of pure titanium and titanium-zirconium alloy implants, and to provide reference for the studies of implant surface modification. Methods: The pure titanium group, the hydrophilic pure titanium group, the titanium zirconium alloy group and the hydrophilic titanium-zirconium alloy group were prepared by sandblasting and acid-etching or hydrophilic sandblasting and acid-etching, (11 specimens in each group). The surface morphology and surface properties of four types of titanium specimens were analyzed by surface contact angle meter, scanning electron microscope (SEM), optical profilometer, atomic force microscope (AFM) and Raman spectrometer. Results: The surface contact angles of hydrophilic pure titanium and hydrophilic titanium-zirconium alloy were 1.6°±0.3° and 1.5°±0.2°, and the surface contact angles of pure titanium and titanium-zirconium alloy were 101.4°±4.6° and 96.2°±3.0°, respectively. SEM showed that the nano-protrusions on the surface of pure titanium and titanium-zirconium alloys were less or even absent, while the nano-protrusions on the surface of hydrophilic pure titanium and hydrophilic titanium-zirconium alloys were relatively more; the nano-protrusions on the surface of hydrophilic pure titanium surface were small and dense relatively, but the nano-protrusions of the hydrophilic titanium-zirconium alloy had large diameters and were dispersed relatively. The optical profiler and AFM showed that the surface roughness of hydrophilic pure titanium and hydrophilic titanium-zirconium alloy was significantly higher than that of pure titanium and titanium-zirconium alloy (P<0.05). Raman spectroscopy showed that only the amorphous TiO(2) was present on the surface of the pure titanium group, while the rutile TiO(2) characteristic peak was observed in the other three groups, but the lateral inhomogeneity was observed. After Raman shift 610 cm(-1), the Raman spectra of four groups were similar. Conclusions: Hydrophilic sandblasting and acid-etching treatment can improve the surface hydrophilicity and surface roughness of pure titanium and titanium zirconium alloy, and improve the surface properties of pure titanium and titanium zirconium alloy implants.

Randomized multicentre trial comparing external and internal pancreatic stenting during pancreaticoduodenectomy

BACKGROUND

There is no consensus on the best method of preventing postoperative pancreatic fistula (POPF) after pancreaticoduodenectomy (PD). This multicentre, parallel group, randomized equivalence trial investigated the effect of two ways of pancreatic stenting after PD on the rate of POPF.

METHODS

Patients undergoing elective PD or pylorus-preserving PD with duct-to-mucosa pancreaticojejunostomy were enrolled from four tertiary referral hospitals. Randomization was stratified according to surgeon with a 1 : 1 allocation ratio to avoid any related technical factors. The primary endpoint was clinically relevant POPF rate. Secondary endpoints were nutritional index, remnant pancreatic volume, long-term complications and quality of life 2 years after PD.

RESULTS

A total of 328 patients were randomized to the external (164 patients) or internal (164) stent group between August 2010 and January 2014. The rates of clinically relevant POPF were 24·4 per cent in the external and 18·9 per cent in the internal stent group (risk difference 5·5 per cent). As the 90 per cent confidence interval (-2·0 to 13·0 per cent) did not fall within the predefined equivalence limits (-10 to 10 per cent), the clinically relevant POPF rates in the two groups were not equivalent. Similar results were observed for patients with soft pancreatic texture and high fistula risk score. Other postoperative outcomes were comparable between the two groups. Five stent-related complications occurred in the external stent group. Multivariable analysis revealed that soft pancreatic texture, non-pancreatic disease and high body mass index (23·3 kg/m² or above) predicted clinically relevant POPF.

CONCLUSION

External stenting after PD was associated with a higher rate of clinically relevant POPF than internal stenting. Registration number: NCT01023594 (https://www.clinicaltrials.gov).

Portal vein patency after pancreatoduodenectomy for periampullary cancer

BACKGROUND

The fate of the portal vein (PV) after pancreatoduodenectomy, especially its long-term patency and associated complications, has received little attention. The aim of this study was to explore the long-term patency rate of the PV after pancreatoduodenectomy, focusing on risk factors for PV stenosis/occlusion and associated complications.

METHODS

Serial CT images of patients who underwent pancreatoduodenectomy for periampullary cancer between January 2000 and June 2012 in a single institution were evaluated for PV stenosis or occlusion.

RESULTS

A total of 826 patients were enrolled. The PV stenosis/occlusion rate after pancreatoduodenectomy was 19.6 per cent and the 5-year patency rate 69.9 per cent. The most frequent cause of PV stenosis/occlusion was local recurrence followed by postoperative change and PV thrombosis. Patients who underwent PV resection had a higher PV stenosis/occlusion rate than those who did not (51 versus 17.4 per cent; P < 0.001). The 3-year patency rate was highest in patients with cancer of the ampulla of Vater and lowest in patients with pancreatic cancer (91.9 versus 55.5 per cent respectively; P < 0.001). Multivariable analysis showed that risk factors for PV stenosis/occlusion included primary tumour location, chemoradiotherapy and PV resection. PV stenosis or occlusion without disease recurrence was observed in 17.3 per cent of the patients. PV resection and grade B or C pancreatic fistula were independent risk factors for PV stenosis/occlusion. Among 162 patients with PV stenosis or occlusion, five (3.1 per cent) had fatal recurrent gastrointestinal bleeding.

CONCLUSION

PV stenosis or occlusion is common after pancreatoduodenectomy, particularly if the PV has been resected and/or chemoradiotherapy was given after surgery. Although recurrence is the most frequent cause of PV stenosis/occlusion, this complication is found in a significant proportion of patients without disease recurrence.

Validation of international consensus guidelines for the resection of branch duct-type intraductal papillary mucinous neoplasms

Background

Classifications of intraductal papillary mucinous neoplasm (IPMN) remain ambiguous, especially for the mixed type. Factors predicting malignancy remain unclear. The aim of this study was to evaluate the usefulness of factors predicting malignancy in the new international consensus guidelines for resection of branch duct-type (BD)-IPMN and to compare them with those in the previous version.

Methods

A prospectively collected database of patients with biopsy-proven BD-IPMN was analysed to compare factors between the first and second consensus guidelines, particularly as predictors of malignancy.

Results

Of 350 patients with BD-IPMN, sensitivity (0·724) and balanced accuracy (0·751) of the second guidelines were superior to those (0·639 and 0·730) in the first version at the expense of slightly reduced specificity (0·779 versus 0·822 for the first version) by random forest models. Multiple logistic regression analysis showed that main pancreatic duct dilatation greater than 5 mm (hazard ratio (HR) 4·54, 95 per cent confidence interval 2·45 to 8·41; P &lt; 0·001), mural nodules (HR 6·27, 3·27 to 12·01; P &lt; 0·001) and carbohydrate antigen 19–9 level above 37 units/ml (HR 4·03, 1·83 to 8·90; P = 0·001) were independent predictors of BD-IPMN malignancy.

Conclusion

The new consensus guidelines provide better sensitivity, performance of factors predicting malignancy, and balanced accuracy in the diagnosis of BD-IPMN malignancy. Size alone was limited in predicting malignancy. Variability in clinical significance of the individual factors associated with a risk of malignancy indicates the need for a tailored approach in the management of patients with BD-IPMN.

Effects of pancreatectomy on nutritional state, pancreatic function and quality of life

Background

There are concerns about the extent of impaired endocrine and exocrine pancreatic function and poor quality of life (QoL) after pancreatectomy, but there is little information from large prospective follow-up studies.

Methods

Consecutive patients undergoing pancreaticoduodenectomy or distal pancreatectomy between 2007 and 2011 were included. Relative bodyweight (RBW), triceps skinfold thickness (TSFT), serum protein, albumin, transferrin, fasting blood glucose, postprandial 2-h glucose (PP2), glycosylated haemoglobin A1c and stool elastase measurements, and European Organization for Research and Treatment of Cancer QLQ-C30 questionnaires were collected serially for 1 year.

Results

Some 136 patients undergoing pancreatic resection completed the study. RBW and TSFT recovered to over 90 per cent of the preoperative value by 12 months, whereas transferrin, albumin and protein had returned to preoperative levels by 3 months. Diabetes mellitus, impaired fasting glucose or raised PP2 was present in 42 of 76 patients at 6 months and 36 of 76 at 12 months. Although steatorrhoea and diarrhoea had mainly resolved by 3 months, stool elastase level decreased after operation and showed no recovery. Nutritional status, pancreatic endocrine function and QoL returned to preoperative levels in 63 (46·3 per cent), 72 (52·9 per cent) and 77 (56·6 per cent) of 136 patients within 6 months of pancreatectomy. Multivariable analysis revealed that age 60 years or more, operation type, chronic pancreatitis and malignant disease had a significant impact on nutritional index, pancreatic function and QoL.

Conclusion

About half of all patients can expect recovery from pancreatectomy after 6 months, but those with risk factors need more careful follow-up and supportive management.

Three minimum wet thickness regions of slot die coating

An experimental study was carried out to determine the minimum wet thickness of slot die coating for low-viscosity solutions. There exist three distinct coating regions (I, II, and III), depending on the physical properties of the coating fluid, die geometry, and flow conditions. A critical Reynolds number was found, below which viscous and surface tension effects are important. In Region I, the minimum wet thickness increases with increasing capillary number and becomes independent of capillary number in Region II. Region III exists above the critical Reynolds number where fluid inertia is dominant. In this region, the minimum wet thickness decreases as Reynolds number increases. Flow visualization on the coating bead reveals that the position of the downstream meniscus of the coating bead determines the types of coating region, whereas the shape and position of the upstream meniscus determine the type of coating defects. It was also observed that the downstream meniscus was not located at the die lip corner and both the static and dynamic contact angles varied under different conditions. These findings are critical for realistic theoretical study of slot die coating.

Functional analysis of C-terminal deletion mutants of Epstein-Barr virus thymidine kinase

Thymidine kinase (TK) activity was detected following expression of the TK gene of Epstein-Barr virus (EBV) using the pET expression plasmid and E. coli BL21 (DE3)pLysS. To study the amino acid residues required at the C terminus of the EBV TK protein for enzymatic activity, a series of C-terminal deletion mutants was generated by direct truncation, linker insertion or PCR mutagenesis to create stop codons at particular sites. Deletion of nine residues from the C terminus caused a 35% reduction in TK activity, while a ten-residue deletion completely abolished the activity. A single point mutation at residue Cys570, corresponding to Cys336 of herpes simplex virus TK, did not alter the TK activity. Single amino acid changes within the last seven to ten residues also did not affect activity. The results indicate that maintenance of the conformation of the C terminus is important for enzyme activity.

Helicobacter Pylori Infection in Patients with Gastric Adenocarcinoma

We examined the biologic tumor behavior in Helicobacter pylori-seropositive patients with gastric adenocarcinoma. A total of 214 consecutive patients with pathologically confirmed adenocarcinoma of the stomach who underwent gastric resection were studied. The stored serum samples were tested for serum antibody to H. pylori by using a highly sensitive and specific IgG enzyme-linked immunosorbent assay. The difference in H. pylori-seropositive and seronegative patients with gastric adenocarcinoma was evaluated in terms of various clinicopathologic parameters. A multivariate logistic regression analysis was used to adjust for potential confounding variables. Antibodies to H. pylori were detected in 65.9% of patients with gastric adenocarcinoma. H. pylori-seropositive patients were younger than seronegative patients and had infiltrative tumor according to Ming's criteria. When adjusted for age, infiltrative tumor come out stronger. These findings suggest that H. pylori infection may be related to infiltrative type gastric adenocarcinoma; further study is necessary.

Evaluation of a once-a-day theophylline preparation in asthmatic children

We conducted a study to evaluate the serum theophylline concentrations and dose interval of Theolan preparation in asthmatic children. A series of serum theophylline levels were measured both in 10 asthmatic children taking Theolan once a day and 9 children twice a day. In the once-a-day group, the peak serum theophylline level was greater than 20 micrograms/ml; whereas, in the twice-a-day group, it was mostly between 10 and 20 micrograms/ml. The difference of the peak-to-trough was more fluctuant in the once-a-day group than in the twice-a-day group. These results suggest that Theolan given once a day in the evening can be useful in the management of nocturnal asthma; however, it was difficult for once-a-day administration of Theolan to sustain rigid therapeutic serum theophylline levels. Because of rapid metabolism in children, they may require a more frequent interval than once-a-day dosing to suppress the symptoms of chronic asthma.

A rapid cold agglutinin test in Mycoplasma pneumoniae infection

A definite diagnosis of Mycoplasma pneumoniae infection is currently based on cultural method or complement fixation test which is usually retrospective. A rapid cold agglutinin test was developed to determine its value on the early diagnosis of M. Pneumoniae infection. One hundred and thirty patients with pneumonia aged between 5 and 14 years were studied. Blood specimens from all the patients were collected for rapid cold agglutinin test, cold hemagglutination test, and complement fixation test. Thirty patients showed positive, rapid cold agglutinin test. All the patients with positive rapid cold agglutinin test had higher (greater than or equal to 1:32) cold agglutinin titers which were simultaneously performed. The rapid cold agglutinin test had 100% sensitivity and 97% specificity when a cut-off criterion was set at cold agglutinin titer greater than or equal to 1:64. Twenty-five of the 130 cases were serologically proven to have M. pneumoniae infection using complement fixation test or/and cold agglutinin titer. M. pneumoniae was a major cause (21/28) in cold agglutinin-positive pneumonic patients. The positive predictive value of the rapid cold agglutinin test is 70% (21/30). Only 28% (7/25) of the patients with M. pneumoniae infection were diagnosed at acute stage with serological method. We conclude that the rapid cold agglutinin test is of much value in the early detection of M. pneumoniae infection in office or hospital practice in children with pneumonia.

The relation between Campylobacter pylori and inflammatory cell infiltration of antral mucosa in patients with dyspepsia

In order to understand the relation between the prevalence of Campylobacter pylori and the severity of gastritis, we conducted a survey of 166 randomly selected dyspeptic patients. The presence of C. pylori on the antral mucosa was aseptically determined by both urease and bacterial culture tests. Specimens of antral mucosa were obtained for pathologic gradings of inflammation: active gastritis, mononuclear cell infiltration C0 (nil) to C3 (lymphoid follicle); presence or absence of intestinal metaplasia. Pathologically, chronic gastritis was invariably present in almost all patients with dyspepsia: three-fourths of them showed evidence of active gastritis, one-third showed intestinal metaplasia. Half of the dyspeptic individuals had C. pylori colonization. The results suggest that the prevalence of C. pylori was closely related to the different grades of active gastritis; neither the different grades of chronic gastritis nor intestinal metaplasia affected the prevalence of C. pylori on gastric mucosa. We conclude from this study that C. pylori is closely related to active chronic gastritis because of the common presence of chronic gastritis in patients with dyspepsia.