Up to 300 K lasing with GeSn-On-Insulator microdisk resonators

GeSn alloys are the most promising direct band gap semiconductors to demonstrate full CMOS-compatible laser integration with a manufacturing from Group-IV materials. Here, we show that room temperature lasing, up to 300 K, can be obtained with GeSn. This is achieved in microdisk resonators fabricated on a GeSn-On-Insulator platform by combining strain engineering with a thick layer of high Sn content GeSn.

Assessment of self-efficacy for caregiving in oncology: Italian validation of the caregiver inventory (CGI-I)

Background

The Caregiver Inventory (CGI), a measure of self-efficacy for caregiving that takes into account aspects of caregiving that are neglected by current measures of caregiving, was translated into Italian and validated.

Methods

Ninety-one caregivers from a variety of locations in Italy completed the CGI-Italian (CGI-I) as well as the Hospital Anxiety and Depression Scale (HADS) and the Family Strain Questionnaire - Short Form (FSQ-SF).

Results

A confirmatory factor analysis based on the original CGI factor structure resulted in an adequate fit of the CGI-I using standard fit indices. Thus, the original factor structure was validated in the CGI-I: Managing Medical Information (α = 0.87), Caring for Care Recipient (α = 0.68), Caring for Oneself (α = 0.78), and Managing Difficult Interactions/Emotions (α = 0.55). The CGI-I total score was inversely related to anxiety (HADS, r = − 0.35, p = <.05), and depression (HADS, r = − 0.45, p = <.05). In addition, the CGI-I was inversely related to caregiver stress (FSQ-SF, r = − 0.39, p = <.05). Care of Oneself and Managing Difficult Interactions/Emotions emerged as the strongest and most robust negative relationships with anxiety, depression, and caregiver stress, which replicated, with similar constructs, findings from the original CGI.

Conclusions

The results of this study established the CGI-I as a reliable and valid measure of self-efficacy for caregiving. This study also confirms the importance of self-care and managing difficult communication in the process of successfully navigating the demands of caregiving and in constructing interventions for caregivers who need support.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12904-021-00849-5.

KRAS p.G12C mutation occurs in 1% of EGFR-mutated advanced non-small-cell lung cancer patients progressing on a first-line treatment with a tyrosine kinase inhibitor

Background

KRAS is mutated in ∼30% of non-small-cell lung cancer (NSCLC) but it has also been identified as one of the mechanisms underlying resistance to tyrosine kinase inhibitors (TKIs) in EGFR-positive NSCLC patients. Novel KRAS inhibitors targeting KRAS p.G12C mutation have been developed recently with promising results. The proportion of EGFR-positive NSCLC tumours harbouring the KRAS p.G12C mutation upon disease progression is completely unexplored.

Materials and methods

Plasma samples from 512 EGFR-positive advanced NSCLC patients progressing on a first first-line treatment with a TKI were collected. The presence of KRAS p.G12C mutation was assessed by digital PCR.

Results

Overall, KRAS p.G12C mutation was detected in 1.17% of the samples (n = 6). In two of these cases, we could confirm that the KRAS p.G12C mutation was not present in the pre-treatment plasma samples, supporting its role as an acquired resistance mutation. According to our data, KRAS^G12C patients showed similar clinicopathological characteristics to those of the rest of the study cohort and no statistically significant associations between any clinical features and the presence of the mutation were found. However, two out of six KRAS^G12C tumours harboured less common EGFR driver mutations (p.G719X/p.L861Q). All KRAS^G12C patients tested negative for the presence of p.T790M resistance mutation.

Conclusions

The KRAS p.G12C mutation is detected in 1% of EGFR-positive NSCLC patients who progress on a first line with a TKI. All KRAS^G12C patients were negative for the presence of the p.T790M mutation and they did not show any distinctive clinical feature.

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Novel KRAS G12C inhibitors provide a new therapeutic opportunity for NSCLC patients.

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One percent of EGFR-mutated NSCLC tumours progressing on a first-line TKI harbour the KRAS p.G12C mutation.

Uniform phosphorus doping of untapered germanium nanowires

One of the major challenges in the growth of vapor-liquid-solid (VLS) nanowires is the control of dopant incorporation in the structures. In this work, we study the n-type doping and morphology of nanowires grown by chemical vapor deposition when HCl is introduced. We obtain fully untapered nanowires with a growth temperature up to 410 °C and measure their resistivity using the 4-probe technique to be 2.0 mΩ cm. We perform energy dispersive x-ray measurements showing a concentration of dopants in the (5-7) × 10¹⁸ cm^-3 range, being radially and axially uniform. The combination of these two measurements shows that the mobility is the same as for bulk germanium, demonstrating that the VLS mechanism has no detrimental effect for the electron transport in these nanowires.

Effect of HCl on the doping and shape control of silicon nanowires

The introduction of hydrogen chloride during the in situ doping of silicon nanowires (SiNWs) grown using the vapor-liquid-solid (VLS) mechanism was investigated. Compared with non-chlorinated atmospheres, the use of HCl with dopant gases considerably improves the surface morphology of the SiNWs, leading to extremely smooth surfaces and a greatly reduced tapering. Variations in the wire diameter are massively reduced for boron doping, and cannot be measured at 600 °C for phosphorous over several tens of micrometers. This remarkable feature is accompanied by a frozen gold migration from the catalyst, with no noticeable levels of gold clusters observed using scanning electron microscopy. A detailed study of the apparent resistivity of the NWs reveals that the dopant incorporation is effective for both types of doping. A graph linking the apparent resistivity to the dopant to silane dilution ratio is built for both types of doping and discussed in the frame of the previous results.

Adverse events risk associated with bevacizumab addition to breast cancer chemotherapy: a meta-analysis

BACKGROUND

Bevacizumab is a monoclonal antibody against vascular endothelial growth factor with the ability to increase progression-free survival in metastatic breast cancer (MBC). A systematic review and meta-analysis was conducted to determine the risk of the most clinically relevant adverse outcomes associated with the use of bevacizumab in the treatment of breast cancer.

PATIENTS AND METHODS

We included phase III clinical trials that used bevacizumab alone or in combination with chemotherapy as for MBC or locally recurrent. Statistical analyses were conducted to calculate summary odds ratio (OR) of the eight most relevant adverse outcomes related with bevacizumab.

RESULTS

Five clinical trials were included in the meta-analysis. Summary odds ratios obtained showed a statistically significant bevacizumab-associated increased risk in four of the adverse outcomes studied: proteinuria (OR = 27.68), hypertension (OR = 12.76), left ventricular dysfunction (LVD) (OR = 2.25), and hemorrhagic events (OR = 4.07). No statistically significant differences were found for gastrointestinal (GI) perforation, vascular events, fatal events, or febrile neutropenia.

CONCLUSIONS

Bevacizumab did increase the risk of LVD and hemorrhagic events. The addition of bevacizumab to chemotherapy in patients with metastatic breast cancer was not associated with a significant increase in grade ≥ 3 arterial or venous thromboembolic events, GI perforation, or fatal events.

Oligodeoxynucleotide IMT504: lack of effect on immune parameters during islet regeneration in single dose streptozotocin-induced diabetes

BACKGROUND

We have shown that oligodeoxynucleotide IMT504 improved blood glucose and islet beta-cell content in streptozotocin (STZ)-induced diabetic rats, inducing early expression of progenitor markers. Here we determined the effect of IMT504 on islet infiltration and on immunomodulatory proteins indoleamine 2,3-dioxygenase (IDO) and TNF-α-stimulated gene/protein 6 (TSG-6) in islets of STZ-diabetic rats, at the time of progenitor markers expression.

METHODS

Male rats were i.p. injected with STZ [60 mg/kg body weight (BW)] or citrate buffer (control) (day 1). Starting on day 4, STZ animals were daily treated with saline (STZ-saline) or IMT504 (20 mg/kg BW/day s.c., STZ-IMT504) and killed after two consecutive decreases in blood glucose. Islet area and insulin expression, CD3 (T lymphocytes), CD68 (macrophages), IDO and TSG-6 immunostainings were determined. Islet infiltration was also evaluated by haematoxylin staining.

RESULTS

STZ-induced diabetes in rats, with an important decrease in islet area was reversed by IMT504. Diabetes development did not involve islet infiltration, determined by haematoxylin and by the absence of significant T lymphocyte and macrophage presence. IMT504 did not induce changes in these parameters. IDO was not expressed in controls; the percentages of IDO-positive islets were very low and similar in STZ-saline and STZ-IMT504. Scarce TSG-6 was expressed in all groups, without significant differences.

CONCLUSIONS

IMT504 improved insulin content but did not alter IDO or TSG-6 staining in islets of STZ-diabetic rats, suggesting that they do not participate in the IMT504-induced repair process. IMT504 did not per se modify leukocyte presence in islets of diabetic rats.

InGaAs quantum dots grown by molecular beam epitaxy for light emission on Si substrates

The aim of this study is to achieve homogeneous, high density and dislocation free InGaAs quantum dots grown by molecular beam epitaxy for light emission on silicon substrates. This work is part of a project which aims at overcoming the severe limitation suffered by silicon regarding its optoelectronic applications, especially efficient light emission device. For this study, one of the key points is to overcome the expected type II InGaAs/Si interface by inserting the InGaAs quantum dots inside a thin silicon quantum well in SiO2 fabricated on a SOI substrate. Confinement effects of the Si/SiO2 quantum well are expected to heighten the indirect silicon bandgap and then give rise to a type I interface with the InGaAs quantum dots. Band structure and optical properties are modeled within the tight binding approximation: direct energy bandgap is demonstrated in SiO2/Si/InAs/Si/SiO2 heterostructures for very thin Si layers and absorption coefficient is calculated. Thinned SOI substrates are successfully prepared using successive etching process resulting in a 2 nm-thick Si layer on top of silica. Another key point to get light emission from InGaAs quantum dots is to avoid any dislocations or defects in the quantum dots. We investigate the quantum dot size distribution, density and structural quality at different V/III beam equivalent pressure ratios, different growth temperatures and as a function of the amount of deposited material. This study was performed for InGaAs quantum dots grown on Si(001) substrates. The capping of InGaAs quantum dots by a silicon epilayer is performed in order to get efficient photoluminescence emission from quantum dots. Scanning transmission electronic microscopy images are used to study the structural quality of the quantum dots. Dislocation free In50Ga50As QDs are successfully obtained on a (001) silicon substrate. The analysis of QDs capped with silicon by Rutherford Backscattering Spectrometry in a channeling geometry is also presented.

Surface recombination velocity measurements of efficiently passivated gold-catalyzed silicon nanowires by a new optical method

The past decade has seen the explosion of experimental results on nanowires grown by catalyzed mechanisms. However, few are known on their electronic properties especially the influence of surfaces and catalysts. We demonstrate by an optical method how a curious electron-hole thermodynamic phase can help to characterize volume and surface recombination rates of silicon nanowires (SiNWs). By studying the electron-hole liquid dynamics as a function of the spatial confinement, we directly measured these two key parameters. We measured a surface recombination velocity of passivated SiNWs of 20 cm s(-1), 100 times lower than previous values reported. Furthermore, the volume recombination rate of gold-catalyzed SiNWs is found to be similar to that of a high-quality three-dimensional silicon crystal; the influence of the catalyst is negligible. These results advance the knowledge of SiNW surface passivation and provide essential guidance to the development of efficient nanowire-based devices.

The evolution of the fraction of Er ions sensitized by Si nanostructures in silicon-rich silicon oxide thin films

Photoluminescence (PL) and time-resolved PL experiments as a function of the elaboration process are performed on Er-doped silicon-rich silicon oxide (SRO:Er) thin films grown under NH(3) atmosphere. These PL measurements of the Er(3+) emission at 1.54 microm under non-resonant pumping with the Er f-f transitions are obtained for different Er(3+) concentrations, ranging from 0.05 to 1.4 at.%, and various post-growth annealing temperatures of the layers. High resolution transmission electron microscopy (HRTEM) and energy-filtered TEM (EFTEM) analysis show a high density of Si nanostructures composed of amorphous and crystalline nanoclusters varying from 2.7 x 10(18) to 10(18) cm(-3) as a function of the post-growth annealing temperature. Measurements of PL lifetime and effective Er excitation cross section for all the samples under non-resonant optical excitation with the Er(3+) atomic energy levels show that the number of Er(3+) ions sensitized by the silicon-rich matrix decreases as the annealing temperature is increased from 500 to 1050 degrees C. The origin of this effect is attributed to the reduction of the density of sensitizers for Er ions in the SRO matrix when the annealing temperature increases. Finally, extended x-ray absorption fine-structure spectroscopy (EXAFS) shows a strong correlation between the number of emitters and the mean local order around the erbium ions.

Recombination dynamics of spatially confined electron-hole system in luminescent gold catalyzed silicon nanowires

We study by time-resolved low temperature photoluminescence (PL) experiments of the electronic states of silicon nanowires (SiNWs) grown by gold catalyzed chemical vapor deposition and passivated by thermal SiO(2). The typical recombination line of free carriers in gold-catalyzed SiNWs (Au-SiNWs) is identified and studied by time-resolved experiments. We demonstrate that intrinsic Auger recombination governs the recombination dynamic of the dense e-h plasma generated inside the NW. In a few tens of nanoseconds after the pulsed excitation, the density of the initial electronic system rapidly decreases down to reach that of a stable electron-hole liquid phase. The comparison of the PL intensity decay time of Au-SiNWs with high crystalline quality and purity silicon layer allows us to conclude that the Au-SiNW electronic properties are highly comparable to those of bulk silicon crystal.

The histone deacetylase inhibitor trichostatin A induces GADD45 gamma expression via Oct and NF-Y binding sites

The GADD45gamma protein is a potential tumor suppressor whose expression is reduced in several tumors. However, very little is known about the regulation of its expression. We have determined that the most relevant region of its promoter lies between nucleotides -112 and -54, relative to the transcription start site. Putative Oct and NF-Y elements were found in this region and factors belonging to these families interacted with these elements in vitro and with the promoter in vivo. Mutation of these elements reduced the basal activity of the promoter, suggesting that both sites are essential for basal expression. These factors interact with chromatin modifying proteins and we found that histone deacetylase 1 or silencing mediator for retinoid and thyroid hormone receptor overexpression reduced the basal activity of the promoter. In contrast, forced expression of the histone acetylase protein PCAF or cell treatment with the HDAC inhibitor trichostatin A increased GADD45gamma mRNA levels and induced GADD45gamma promoter activity through its Oct and NF-Y elements. Moreover, ectopic expression of a dominant-negative version of NF-YA strongly inhibited trichostatin A-induced activation of the promoter. Our data strongly suggest that inhibition of deacetylase activity could potentially be used for treatment of tumors where GADD45gamma expression is reduced.

[Use of blood products in patients treated surgically for stage I non-small cell lung cancer]

OBJECTIVE

Retrospective study on the relation between the use of blood products and survival rates in patients treated surgically for stage I non-small cell lung cancer (NSCLC).

PATIENTS AND METHODS

The study included 856 patients who underwent surgical resection from 1969 to 2000 for stage I NSCLC, classified histologically according to the current guidelines of the Spanish Society of Pulmonary and Thoracic Surgery (SEPAR). Patients who died in the postoperative period were excluded from the study. A series of clinicopathological variables were recorded, including the perioperative use or not of blood products. Descriptive, univariate, and multivariate statistical analyses were performed. Follow up concluded in December of 2003.

RESULTS

One hundred twenty-five patients (14.6%) underwent a perioperative transfusion. A significant association was found between the use of blood products and tumor size (P<.001), pneumectomy (P<.001), and cell type (P<.05). The respective 2, 5, and 10-year survival rates were 78%, 63%, and 54% for the nontransfusion group, and 73%, 59%, and 46% for the transfusion group. Both survival curves were compared and no significant differences were found (P=.23). Multivariate regression analysis included tumor size, patient age, and histologic cell type (squamous cell carcinoma or not); no relation between transfusion and survival was found.

CONCLUSIONS

In our series, we found no difference in survival rates for patients with stage I NSCLC after perioperative blood transfusion.

Urgent Lung Transplantation in Spain

BACKGROUND

Lung donors are scarce and lung transplantation resources are limited. Because urgent lung transplantation (ULT) is assumed to yield poor results, its use is controversial. We assessed the outcome of patients who received ULT seeking to determine effectiveness and risk factors.

PATIENTS AND METHOD

We collected data from every ULT performed in Spain during 5 years (1998-2002). The survival of patients was studied using Kaplan-Meier, Cox regression, and chi-square statistical analyses. We compared outcomes and perioperative mortality (over 30 days) for ULT procedures, analyzing the influence of certain variables (age, type of transplant, diagnosis, indication, and time on waiting list).

RESULTS

Among 109 patients proposed for the procedure, 73 ULT were performed during the period. The most frequent indications were pulmonary fibrosis (19 cases) and cystic fibrosis (19 cases), showing the worst and the better survival rates, respectively. The bad prognosis, determined mainly by per operative mortality rate (35.62%), was significantly affected by age (worse for patients older than 40 years) and type of LT (single worse than double; P < .05). A longer time waiting for ULT also showed a worse prognosis (P < .005).

CONCLUSIONS

Long-term survival after ULT shows that the procedure is effective and efficient for a select group of patients, despite the high per operative risk. ULT should be reserved for younger patients. It also requires performance in a short period (just a few days), initially rejecting a single lung transplant, provided that the patient is adequately monitored.

[Lung transplantation in cystic fibrosis: perioperative mortality]

OBJECTIVE

To determine the incidence and causes of perioperative mortality following lung transplant for cystic fibrosis.

PATIENTS AND METHODS

We analyzed the cases of 57 patients. Fifty-five patients received double lung transplants, 1 received a heart-double lung transplant, and 1 received a combined double lung and liver transplant. Information related to the organ donor, recipient, lung graft, and early postoperative period was gathered. Perioperative mortality was defined as death resulting from anesthesia or surgery regardless of how many days had passed. The Kaplan-Meier method was used to analyze survival. A Cox logistic regression model was used to determine variables affecting mortality.

RESULTS

Survival was 83.7% at 1 year after transplantation, 77.3% at 2 years, and 66.9% at 5 years. Five (8.7%) patients died as a result of anesthesia or surgery. A ratio of PaO2 to inspired oxygen fraction (FiO2) less than 200 mm Hg in the early postoperative period was observed in 8 (14%) patients. Primary graft failure occurred in 4 patients, due to pneumonia in 2 and to biventricular dysfunction in 2. Three of those patients died. Two patients with PaO2/FiO2 greater than 200 mm Hg died after surgery, one from septic shock due to Pseudomonas cepacia and the other from massive cerebral infarction. PaO2/FiO2 upon admission to the recovery care unit was the only variable significantly associated with perioperative mortality in the logistic regression model (P=.0034).

CONCLUSIONS

The only factor significantly related to perioperative mortality in patients receiving transplants for cystic fibrosis was PaO2/FiO2 upon admission to the recovery unit.