Solutions of Eshelby-Type Inclusion Problems and a Related Homogenization Method Based on a Simplified Strain Gradient Elasticity Theory

Eshelby-type inclusion problems of an infinite or a finite homogeneous isotropic elastic body containing an arbitrary-shape inclusion prescribed with an eigenstrain and an eigenstrain gradient are analytically solved. The solutions are based on a simplified strain gradient elasticity theory (SSGET) that includes one material length scale parameter in addition to two classical elastic constants. For the infinite-domain inclusion problem, the Eshelby tensor is derived in a general form by using the Green’s function in the SSGET. This Eshelby tensor captures the inclusion size effect and recovers the classical Eshelby tensor when the strain gradient effect is ignored. By applying the general form, the explicit expressions of the Eshelby tensor for the special cases of a spherical inclusion, a cylindrical inclusion of infinite length and an ellipsoidal inclusion are obtained. Also, the volume average of the new Eshelby tensor over the inclusion in each case is analytically derived. It is quantitatively shown that the new Eshelby tensor and its average can explain the inclusion size effect, unlike its counterpart based on classical elasticity. To solve the finite-domain inclusion problem, an extended Betti’s reciprocal theorem and an extended Somigliana’s identity based on the SSGET are proposed and utilized. The solution for the disturbed displacement field incorporates the boundary effect and recovers that for the infinite-domain inclusion problem. The problem of a spherical inclusion embedded concentrically in a finite spherical body is analytically solved by applying the general solution, with the Eshelby tensor and its volume average obtained in closed forms. It is demonstrated through numerical results that the newly obtained Eshelby tensor can capture the inclusion size and boundary effects, unlike existing ones. Finally, a homogenization method is developed to predict the effective elastic properties of a heterogeneous material using the SSGET. An effective elastic stiffness tensor is analytically derived for the heterogeneous material by applying the Mori-Tanaka and Eshelby’s equivalent inclusion methods. This tensor depends on the inhomogeneity size, unlike what is predicted by existing homogenization methods based on classical elasticity. Numerical results for a two-phase composite reveal that the composite becomes stiffer when the inhomogeneities get smaller

Earnings Management for Second-time IPOs: Evidence from China

In China’s IPO market, firms that fail in their first IPO application make considerable adjustments before making their second IPO application. Examining firms that applied for IPOs during 2004-2018, we find that failed IPO applicant firms “package” themselves to obtain approval of the China Securities Regulatory Commission (CSRC) by reducing accrual earnings management and increasing real earnings management. In addition, after a successful second IPO application, these firms relax their vigilance vis-à-vis the CSRC and increase both accrual and real earnings management. This pre-IPO “packaging” behavior deceives investors, leading to higher IPO prices and higher post-IPO returns

Decellularization procedures of the elements of the umbilical-placental complex

Introduction. Due to its antifibrotic, anti-inflammatory and immunomodulatory properties, DAM (Decellularized amniotic membrane) has been used in multiple medical applications for over 100 years. Multiple decellularization methods that include combinations of physical, hemical, and enzymatic treatments are studied to ensure maintaining the structural and chemical integrity of the ECM (extracellular matrix) corresponding to the original tissue. Aim of study. To evaluate the decellularization of the elements of the umbilical-placental complex, by various methods and to characterize the decellularization effect obtained. Methods and materials. Amniotic membranes were manually separated, under sterile conditions, from three human placentas. A total of four decellularization procedures were used: 1% Triton X-100 solution; Triton X-100 1% solution + Ultrasound; 0.5% Dodecyl Sodium Sulfate (SDS) solution; 0.5% SDS solution + Ultrasound,. Evaluation was done after 5 hours and 24 hours. DAM morphology was assessed by hematoxylin and eosin (H&E) staining. Results. Histological images confirm that decellularization of AM with 0.5% SDS solution for 24 hours had a more aggressive influence on the structure of AM. Decellularization of AM with Triton 1% solution after 24 hours shows incomplete decellularization of AM. In the batch in which decellularization was performed with SDS 0.5% and SDS 0.5% solution + Ultrasound, already after 5 hours, the cells were completely removed, without affecting the structure of the ECM of AM. Conclusion. The method of decellularization with 0.5% SDS solution is more suitable for AM decularization and can be performed in only 5 hours, the use of ultrasound did not have a significant effect on the obtained results

Tendințele evoluției varicelei la copii în contextul pandemiei COVID-19 în Republica Moldova

Introducere. În ultimele două decenii, vaccinarea universală împotriva varicelei cu una sau două doze a fost implementată în peste 50 de țări, iar programele de vaccinare au redus incidența varicelei cu 81 și 92% pentru regimurile cu o singură și două doze, respectiv. Multiple studii, publicate recent, au demonstrat că pandemia COVID-19 a perturbat substanțial morbiditatea prin varicelă la copii, nivelul sporit al căreia a fost remarcat, în special, la populația pediatrică din țările fără acoperire vaccinală universală contra acestei afecțiuni. În Programul Național de Imunizări din Republica Moldova nu regăsim și vaccinarea împotriva varicelei. Scopul. Analiza particularităților clinico-evolutive ale varicelei la copiii spitalizați în timpul pandemiei COVID-19. Material și metode. Studiul observațional descriptiv a inclus 2 loturi de pacienți, tratați în cadrul IMSP Spitalul Clinic Municipal de Boli Contagioase de Copii din Chișinău, Republica Moldova, în perioadele ascensiunii epidemice ale varicelei (lunile octombrie-mai), anii 2016-2017 (lotul I – 53 copii) – perioada prepandemică Covid-19 și, respectiv, 2021-2022 ( lotul II – 97 copii) – perioada Covid-19, precum și datele rapoartelor statistice privind morbiditatea prin unele maladii infecțioase și parazitare. Pentru studierea datelor colectate au fost utilizate metode tradiționale de analiză epidemiologică. Rezultate. Analiza datelor statistice la nivel de țară a relevat un număr mai mare de cazuri de varicelă în lunile octombrie – mai 2016-2017 (n=9593), comparativ cu aceeași perioadă în 2021-2022 (n=7318), cu o pondere de 56,12% și, respectiv, 58,01% la copiii de 3-6 ani. Comparativ cu perioada octombrie – mai 2016-2017, numărul pacienților cu varicelă, care au necesitat spitalizare, a crescut dublu în perioada 2021-2022 (p<0,001). Numărul sporit de spitalizări a fost determinat de evoluția mai severă, cu complicații specifice și nespecifice ale bolii. Varicela, în ambele loturi de pacienți, a evoluat tipic, cu erupție veziculoasă difuză și cu sindrom toxic moderat, dar cu complicații mai frecvent înregistrate în lotul II, comparativ cu lotul I (64,9% vs 30,2%, p<0,001). În perioada de studiu 2021-2022, comparativ cu perioada pre-Covid-19, a fost înregistrat un număr mai mare de complicații specifice (encefalite, meningoencefalite, cerebelite, pneumonii virale, laringite – 3,77% vs 13,40%, p>0,05), în special la copiii mai mari de 3 ani. Complicațiile nespecifice (infecțiile pielii și ale țesuturilor moi, pneumonii, artrite – 26,41% vs 51,54%, p>0,05) au agravat evoluția varicelei la copiii mici (până la 3 ani). În lotul II au fost înregistrate și 5 cazuri de varicelă neonatală. Evoluția bolii, administrându-se tratamentul cu aciclovir, în unele cazuri apelându-se la corticoterapie, antibioticoterapie, a fost una favorabilă, nefiind înregistrate decese. Concluzii. Infecția Covid-19 a influențat evoluția și severitatea varicelei la copii. A fost înregistrată o evoluție mai severă, cu necesitate mai înaltă de spitalizare, complicații specifice și nespecifice în diferite grupuri de vârstă. Implementarea acoperirii vaccinale universale împotriva varicelei ar putea soluționa problemele legate atât de micșorarea morbidității prin varicelă, cât și ar putea preveni dezvoltarea unui număr mare de forme severe. cu complicații. în diferite perioade pandemice

Epidemiological particulars of family focuses with COVID-19

Nicolae Testemitanu State University of Medicine and Pharmacy, Republic of Moldova, PMSI Municipal Clinical Hospital of Contagious Diseases for Children, Chisinau, Republic of MoldovaIntroduction. An outbreak of the coronavirus disease 2019 (COVID‐19) is spreading rapidly around the world, which is caused by severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) infection. The population of all ages is susceptible to SARS-CoV-2 virus. The Johns Hopkins Bloomberg School of Public Health study group showed that children are at similar risk to infection as adults, but that they have fewer symptoms. The role of children in the transmission of SARS-CoV-2 and their susceptibility to mild or asymptomatic infections has been the subject of intense debate. However, it is important to determine the role of the child in maintaining and intensifying of COVID-19 cases. Data from China had showed that most children with COVID-19 were associated with family clusters, where strict social distancing measures have been implemented and 77% of pediatric cases had household exposure. While another data from other studies, such as the Netherlands, suggest that SARS-CoV-2 is spread mainly among adults and from adult family members to children. But emerging evidence suggests children are at greater risk of COVID-19 infection than initially predicted. Material and methods. The determination of the epidemiological peculiarities of the family outbreaks with COVID-19, depending on the children age, the onset of the disease, the living environment, belonging to communities was performed based on a descriptive study. The research group of 160 family outbreaks, which required hospitalization in Municipal Clinical Hospital of Contagious Diseases for Children, during January - February 2021, were included. Results. The number of family outbreaks has increased in January (n=72) vs. February (n= 88). The rate of outbreaks involving school-age children increased from 37.5% in January to 53.4% in February. The onset of the disease in family outbreaks varies depending on the age group of the children. In outbreaks with children aged 0-6 years initially make parents ill in 40.7%, or concomitant onset in 32.55% of cases and 32.55% of outbreaks the onset of the disease occurs in children. In school-age children’s outbreaks, the child is the first who manifest the disease 51.35%, outbreaks with the onset of the disease in parents 41.9%, or concomitant onset 6.75% of cases. It follows a trend of increasing the share of outbreaks in which children are the primary sources of infection, increasing outbreaks from rural areas (from 18.1% to 22.73%), and outbreaks involving organized children (from 43% to 62.5%) which indicates a much higher risk transmission of Covid-19 infection in children's communities. Conclusions. Therefore, children are sources of infection in COVID-19, being responsible for family outbreaks, in about a third of the cases they were the first to show the disease, especially school-age children. Determining the epidemiological features in family outbreaks represent one of the important conditions in developing strategies for action and response to COVID-19 infection in the community

Particularități epidemiologice ale focarelor familiale COVID-19 cu implicarea copiilor

Introduction. The population of all ages is susceptible to SARS-CoV-2 virus. It is important to determine the role of the child in COVID-19 cases maintenance and spreading. Some research showed that most COVID-19 cases in children were associated with their families. Material and methods. The descriptive study is carried out on the basis of family outbreaks epidemiological peculiarities evaluation, concerning the age of the children, the onset of the disease, communities living environment. The research group included 160 family outbreaks, which required hospitalization at MCHCDC PMSI, between January and February 2021. Results. The number of family outbreaks increased (n=88 versus n=72) in February versus January 2021. The rate of outbreaks in schoolchildren increased from 37.5% in January to 53.4% in February. The onset of the disease in the outbreaks varies depending on the age category of the involved children: in 0-6 years - the parents become initially ill (40.7%) or the disease begins simultaneously (32.55%). In school-age children outbreaks in about half of the cases (51.35%) the children manifest the disease the first. There is a tendency of outbreaks percentage increase in the cases where the children, the organized ones as well (from 43% to 62.5%) constitute the primary source of infection. Conclusions. SARS-CoV-2 viral infection epidemiological particularities evaluation in family outbreaks is one of the most important conditions in developing action and response strategies to COVID-19 infection in the community.Introducere. Populația de toate vârstele este susceptibilă la SARS-CoV-2. Este important însă să se determine rolul copilului în menținerea și răspândirea cazurilor de COVID-19. Unele cercetări au arătat că majoritatea cazurilor de COVID-19 la copii au fost asociate familiei. Material și metode. Determinarea particularităților epidemiologice ale focarelor familiale, în funcție de vârsta copiilor, debutul bolii, mediul de trai, apartenența la colectivități a fost realizată în baza unui studiu descriptiv. Lotul de cercetare a inclus 160 de focare familiale, care au necesitat spitalizare în IMSP SCMBCC, în perioada ianuarie-februarie 2021. Rezultate. În luna februarie vs luna ianuarie 2021 a crescut numărul de focare familiale (n=88 vs n=72). Rata focarelor cu implicarea elevilor s-a majorat de la 37,5% în ianuarie până la 53,4% în luna februarie. Debutul bolii în focarele familiale variază în funcție de categoria de vârstă a copiilor implicați: vârsta 0-6 ani - inițial se îmbolnăvesc părinții (40,7%) sau se înregistrează un debut concomitent al bolii (32,55%); vârstă școlară - în circa o jumătate dintre cazuri (51,35%) copilul primul manifestă boala. Se atestă o tendință de creștere a ponderii focarelor în care copii reprezintă surse primare de infecție, precum și a focarelor cu implicarea copiilor organizați (de la 43% la 62,5%). Concluzii. Determinarea particularităților epidemiologice ale infecției cu virusul SARSCoV-2 în cadrul focarelor familiale reprezintă una dintre condițiile importante în elaborarea strategiilor de acțiune și de răspuns la infecția COVID-19 în comunitate

Facile synthesis of Cu and Cu@Cu-Ni nanocubes and nanowires in hydrophobic solution in the presence of nickel and chloride ions

In this work, we report an example of the facile synthesis of methyl methacrylate/tert-butyl acrylate (MMA/tBA) gradient copolymers (poly(MMA-grad-tBA) using the Cu(0) and conventional ATRP ligands as catalysts in DMF solvent at 25 degrees C. Semi-batch copper(0)-mediated living radical copolymerization technique (Cu(0)-mediated LRP) was used for achieving the chain gradient microstructure of the resulting copolymers. We also compared copolymerizations with two different ATRP ligands at ambient temperature allowing control over the molecular weight and polydispersity with a quarter of catalyst concentration versus a conventional ATRP in dipolar protic solvent (i.e. DMF), while the reaction temperature up to 80 degrees C in a non-polar medium (i.e. toluene) in order to reach the above polymerization efficiency. The addition of a small amount of reducing agent (i.e. hydrazine hydrate) into the reaction system allows the reaction proceeding in the oxygen tolerant system without losing control and decreasing total conversion such as using the reagents without deoxygenating

Cardiac tamponade, a rare complication of gastric cardia cancer resection after neoadjuvant chemotherapy combined with immunotherapy: a case report and literature review

Transthoracic cardia resection is a technically well-established surgical procedure. However, acute cardiac tamponade in the early postoperative period is extremely rare. The occurrence is life-threatening to the patient. It also poses a great clinical challenge for perioperative management. To date, few cases of pericardial tamponade have been reported in gastric cancer resection performed after neoadjuvant chemotherapy combined with immunotherapy. We present the case of a 62-year-old woman who received neoadjuvant chemotherapy combined with immunotherapy before surgery, followed by transthoracic surgery. A life-threatening complication, pericardial tamponade, occurred in the early postoperative period. The successful outcome was achieved in through multidisciplinary collaboration

Preparation of Bimetallic Core-shell Nanoparticles with Magnetically Recyclable and High Catalytic Abilities

Conference Name:IUMRS International Conference in Asia (ICA). Conference Address: Taipei, TAIWAN. Time:SEP 19-22, 2011.In this work, we report the preparation of bimetallic core-shell nanoparticles (NPs) using a simple solution synthetic route. A typical example is the Ag@Ni NPs that are synthesized using oleylamine as solvent and reducing agent. The as-obtained Ag@Ni NPs exhibit a spherical morphology and a highly narrow size distribution. Excellent catalytic properties for the H-2 generation from dehydrogenation of sodium borohydride in aqueous solutions are observed. Similar synthetic strategies have also been developed for the preparation of other bimetallic core-shell NPs, such as Ag@Co and Cu@Ni NPs. These bimetallic core-shell NPs are promising candidates for novel optical and magnetic materials as well as high-performance catalysts. (C) 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of MRS-Taiwa