Litterfall decomposition of coffee shaded with Tectona grandis or in full sun

ABSTRACT Litterfall is an important source of soil nutrients, but its decomposition can be affected by the crop system used. The objective of this study was to evaluate litterfall decomposition and macronutrient stocks in coffee crop systems in shaded (SHCS) environments and those in full sun (FSCS). The experiment was conducted on a rural property in Cacoal, state of Rondônia, Brazil, in a 2 × 6 factorial scheme with two crop systems (SHCS and FSCS), and six litterfall decomposition evaluation times (0, 30, 60, 180, 300, and 360 days after the litterfall was returned to the soil (DAL)), with seven replicates. The constant of decomposition (k), half-life time (t1/2) at 360 DAL, and phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), and nitrogen (N) concentrations of the remaining litterfall were determined at each evaluation time. The litterfall in the SHCS had a greater weight loss and constant of decomposition and a lower half-life time at the last evaluation, and the weight loss increased as a function of decomposition time. The litterfall stocks of macronutrients N, P, K, Ca, and Mg showed a linear decrease throughout the decomposition time, and increases in sulfur stock were found at the last evaluation.

ANALISIS KEAUSAN SHAFT PADA FRONT IDLER EXCAVATOR (BACKHOE) HITACHI TIPE EX-100

Backhoe merupakan salah satu jenis excavator yang banyak digunakan pada aplikasi pertanian dan konstruksi sebagai peralatan penggali, pengangkat dan pemuat. Lokasi kerja backhoe yang berpasir dan berbatu akan mempercepat keausan pada komponen undercarriage utamanya pada komponen front idler, yaitu pada shaft. Data yang ada shaft selalu mengalami kerusakan dengan waktu penggunaan kurang dari setahun. Untuk itu penulis tertarik untuk melakukan analisis keausan shaft pada front idler backhoe Hitachi tipe Ex-100 yang sering terjadi di Dinas Bina Marga Kabupaten Kudus, sehingga ke depan kerusakan pada sistem track ini dapat diminimalkan. Beberapa tahapan yang dilakukan dalam penelitian ini antara lain: pengamatan cara kerja operator dan lokasi kerja backhoe, mengamati kerusakan yang terjadi pada komponen front idler, pengukuran dimensi awal dan dimensi setelah aus pada komponen front idler yaitu pada idler, shaft dan bushing, uji kekerasan material komponen front idler di POLINES, dan pengolahan data serta melakukan analisis penyebab kerusakan. Shaft front idler mengalami keausan abrasif yang dapat dilihat dari goresan-goresan yang nampak pada lokasi keausan pada shaft. Tegangan maksimum yang terjadi pada area kontak sebesar 2,05 kN/mm2. Seharusnya shaft mempunyai life time lebih dari 6 tahun tetapi terjadi keausan pada shaft sebesar 13 mm dalam waktu kurang dari 1 tahun. Hal ini dikarenakan adanya faktor eksternal yaitu pasir dan bebatuan yang mempercepat terjadinya abrasi pada shaft.

Management of Appendicitis

Appendicitis is one of the most common causes of acute abdomen with life time risk between 6 and 8% and it’s a most common non obstetric surgical emergency during pregnancy. Appendicitis is claimed to be unknown in the villages of India and China in paper by A. M. Spencer. The reason is simply due to the fact that diagnostic facilities do not exist and cases are not recognized. So diagnosing acute appendicitis accurately and efficiently can reduce morbidity and mortality from perforation and other complications. Surgical intervention is the first choice for appendicitis with medical management being reserved for special situations.

Heavy-Atom Tunneling in the Covalent/Dative Bond Complexation of Cyclo[18]carbon–piperidine

Recent quantum chemical computations demonstrated the electron-acceptance behavior of this highly reactive cyclo[18]carbon (C18) ring with piperidine (pip). The C18–pip complexation exhibited a double-well potential along the N–C reaction coordinate, forming a van der Waals (vdW) adduct and a more stable, strong covalent/dative bond (DB) complex by overcoming a low activation barrier. By means of direct dynamical computations using canonical variational transition state theory (CVT), including the small-curvature tunneling (SCT), we show the conspicuous role of heavy atom quantum mechanical tunneling (QMT) in the transformation of vdW to DB complex in the solvent phase near absolute zero. Below 50 K, the reaction is entirely driven by QMT, while at 30 K, the QMT rate is too rapid (kT ~ 0.02 s-1), corresponding to a half-life time of 38 s, indicating that the vdW adduct will have a fleeting existence. We also explored the QMT rates of other cyclo[n]carbon–pip systems. This study sheds light on the decisive role of QMT in the covalent/DB formation of the C18–pip complex at cryogenic temperatures.

Study of the retina and optic nerve microvascular bed using optical coherence tomography-angiography in post-COVID-19 patients

Introduction. Signs of angioretinopathy are revealed in 7–27.7 % of post-COVID-19 patients. Optical coherence tomographyangiography (OCT-A) allows performing life-time evaluation of structural and microvascular retinal changes in patients after the new coronavirus infection. Aim. To investigate and to compare main microcirculatory parameters of capillary retinal and optic nerve plexuses using OCT-A in patients after COVID-19 of different severity degree. Materials and methods. The main group consisted of 54 people (108 eyes), who recovered from COVID-19 during 3 preceding months. According to the COVID-19 course severity degree, patients were divided into 3 sub-groups. 22 healthy volunteers (44 eyes) were included in the control group. All patients underwent OCT-A. In the angiography regimen, entire vascular density (VD) and that of every sector in the limits of superficial (SCP) and deep (DCP) capillary plexuses, radial peripapillary capillaries (RPC), and in the foveal avascular zone (FAZ). Results. All over parameters investigated no significant differences between control group patients and those of the sub-group with mild COVID-19 course. In patients with moderately severe infectious process course a significant decrease in VD SCP (P<0.01), as well as decrease in VD RPC (P<0.01). In patients with severe and critically severe disease course there was an decrease of VD DCP in the foveal area (P=0.016) and VD FAZ (P<0.01). VD indices correlations with thickness of retinal layers, in which these vascular plexuses are located. In any of the groups, there was no statistically significant enlargement of the FAZ area and no structural optic disc changes. Conclusion. In post-COVID-19 patients, there are signs of capillary blood flow reduction in retinal SCP and RPC, which is proportional to the prior infection severity degree. Associated to COVID-19 microangiopathy is a significant ophthalmologic sign of the new coronavirus infection. Microvascular changes of the retina could play a role of of a new biomarker reflecting the severity degree of the entire vascular system impairment in COVID-19.

LC-MS/MS Method for Determination of Hydroxychloroquine and Metabolites: Application in a Pharmacokinetic Study

Hydroxychloroquine (HCQ) was originally used as an antimalarial and immunomodulation drug. We developed and validated a simple and sensitive ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for simultaneous quantitation of HCQ and its three metabolites in rat blood, and reported their pharmacokinetic parameters. The chromatographic separation and detection of analytes were achieved within 4 min on ZORBAX SB-C8 (3.5 μm, 2.1 × 150 mm) column with gradient elution, and the flow rate was 0.25 mL/min. Simple protein precipitation was successfully applied for sample pretreatment. The HCQ displays a good linearity in the range of 2.0–5000.0 ng/mL, and the three metabolites also show good linearity ranging from 1.0 to 2500.0 ng/mL, with all correlation coefficients (R2) better than 0.98. In conclusion, this rapid, sensitive method was successfully developed, validated, and then applied to a pharmacokinetic study of HCQ in rat model in high dose. The results of the pharmacokinetic study presented an average half-life time 21.14 ± 10.31 h (mean ± SD) of HCQ, which is much shorter in human compared to that in mice. For the three metabolites, longer half-life times (approximately 100 h) were shown in rat.

Koettu työkyky ja hyvinvointitekijät Lapin 40–59-vuotiaassa väestössä

Heikentyneeseen työkykyyn yhteydessä olevien tekijöiden selvittäminen on tärkeää pyrittäessä ehkäisemään työelämästä syrjäytymistä ja parantamaan kuntoutuksen suuntaamista. Työkyvyn muutokset ovat 40 vuotta täyttäneillä yleisempiä kuin nuoremmissa ikäryhmissä. Tutkimuksen tavoitteena oli selvittää sosiaalisten resurssien ja psyykkiseen hyvinvointiin liittyvien tekijöiden yhteyttä työkyvyn heikentymiseen Lapissa asuvilla 40–59-vuotiailla henkilöillä. Tiedonkeruu toteutettiin Lapin sairaanhoitopiirissä syksyllä 2012. Postikyselyn otos oli 8200 henkilöä ja vastausprosentti 33. Ikäryhmään 40–59 vuotta kuului vastanneista 959 (vastausprosentti 32). Heikentynyt työkyky määriteltiin työkykypistemäärän avulla (arvo 0–7 asteikolla 0–10). Analyysimenetelmänä oli logistinen regressioanalyysi. Terveys ja työkyky olivat työssä olevilla paremmat ja eläkeläisillä heikommat kuin työttömillä. Psyykkisen hyvinvoinnin ongelmia oli työttömillä ja eläkeläisillä yhtä paljon. Pääasiallinen toiminta, sosiaalinen tuki, psyykkinen roolitoiminta, depressio ja terveydentila olivat tilastollisesti merkitsevästi yhteydessä heikentyneeseen työkykyyn kokonaismallissa, joka sisälsi myös sosiodemografiset taustamuuttujat. Tietoja työkykyä selittävistä tekijöistä voidaan käyttää hyväksi pohdittaessa työkykyä ylläpitävän toiminnan ja kuntoutuksen mahdollisuuksia. Abstract Perceived work ability and related factors with middle-aged people living in Lapland Perceived work ability predicts continuing at work or withdrawal to disability pension. The aim of the study was to investigate the associations of social, psychological and health factors with work ability in persons aged 40-59 years, living in Lapland. The total sample of the study was 8200 persons and the response rate 33. The number of persons aged 40–59 was 959 (response rate 32). A single-item work ability measure (work ability compared with the life time best) was used. With the unemployed, health and work ability were weaker than with those at work and better than with those at pension. Logistic regression analysis was used in determining the associations of social, psychological and health factors with work ability. In the total model, life situation, social support, psychological role functioning, depression and state of health were statistically significant predictors among all respondents, whereas health was the most important predictor among those at work. Information of factors associated with work ability is needed when developing strategies for rehabilitation and maintaining work ability.

Sperm Storage Costs Determine Survival and Immunocompetence in Newly Mated Queens of the Leaf-Cutting Ant Atta colombica

In the leaf-cutting ant Atta colombica, queens receive ejaculates from multiple males during one single mating event early in their lives. A queen’s fertility and fitness therefore depend on maximizing the number of sperm cells she can store and maintain inside her spermatheca. Previous studies implied significant physiological mating costs, either originating from energetic investments maximizing sperm survival, or from resolving sexual conflicts to terminate male-driven incapacitation of rival sperm via serine proteases found in seminal fluid. Here we conducted an artificial insemination experiment, which allowed us to distinguish between the effects of sperm and seminal fluid within the queen’s sexual tract on her survival and immunocompetence. We found significantly higher mortality in queens that we had inseminated with sperm, independently of whether seminal fluid was present or not. Additionally, after receiving sperm, heavier queens had a higher probability of survival compared to lightweight queens, and immunocompetence decreased disproportionally for queens that had lost weight during the experiment. These findings indicate that queens pay significant physiological costs for maintaining and storing sperm shortly after mating. On the other hand, the presence of seminal fluid within the queens’ sexual tract neither affected their survival nor their immunocompetence. This suggests that the energetic costs that queens incur shortly after mating are primarily due to investments in sperm maintenance and not costs of terminating conflicts between competing ejaculates. This outcome is consistent with the idea that sexually selected traits in social insects with permanent castes can evolve only when they do not affect survival or life-time fitness of queens in any significant way.

Phase reconfiguration of multivalent nickel sulfides in hydrogen evolution

We report a universal phase reconfiguration phenomenon and a doping strategy to enhance the activity of multivalent nickel sulfides in hydrogen evolution. Based on these, a life-time dynamic structure-activity correlation has been established.