Truffle production in the Kingdom of Saudi Arabia – potential and limitation

In Saudi Arabia desert truffles are much appreciated for culinary despite high prices. This is attributed to high demand throughout the year and a limited offer. So far, only naturally occurring truffles have been traded on local markets. The aim of the present investigation was to find out whether it is possible to establish and propagate truffles under semi arid conditions in Saudi Arabia using olive plants as host. The field experiment was installed at Al-Khalidiah Farm-Tebrak situated in the vicinity of Riyadh and comprised an area of 150 ha. Previously raised olive cuttings were inoculated with Tirmania nivea and Tirmania pinoyi and kept under controlled greenhouse conditions prior to be transplanted into the field. Although olive plants developed well, yields of truffles was very weak after four years. The incorporation of a suitable soil on separated areas modified the situation and truffles started to develop well, and up to 14 kg/ha were yielded. Unusual heavy rainfalls, however, inhibited the development of the fruit bodies of truffles resulting in a sharp decrease of the yields. Based on the promising results obtained during a four-year period, it was decided to continue to produce desert truffles taking into account the experiences gained in the past years

Synthesis of Zeolite A from Iraqi Natural Kaolin Using a Conventional Hydrothermal Synthesis Technique

The synthesis of zeolite materials by hydrothermal transformation of kaolin using a conventional hydrothermal method was investigated. Different analytical techniques were used to characterize the starting kaolin and produced zeolite A samples, including scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), x-ray diffraction (XRD), x-ray fluorescence (XRF), thermogravimetric analysis (TGA), and Fourier transform infrared (FT-IR) spectroscopy. The synthetic zeolite type A was obtained after activation of kaolin and metakaolin followed by different thermal and chemical treatments. The metakaolinization phase was achieved by calcining the kaolin in air at 600°C for 3 hours, a much lower temperature than previously reported in the literature. Metakaolin was treated with 3 M sodium hydroxide solution at a ratio of 1:5 and, using stainless steel autoclaves with teflon liners, heated the mixture to 200°C in a microwave for 24 hours. The results from this synthesis route showed that zeolite A with a cubic crystal habit has been successfully synthesized

Mentally Demanding Work and Strain: Effects of Study Duration on Fatigue, Vigor, and Distress in Undergraduate Medical Students

Aims: The impact of the extent of mentally demanding work on the next-day’s strain is largely unknown, as existing studies generally investigate consequences of extended versus normal workdays. The present study sought to fill this gap by investigating how short work periods of mentally demanding academic work impact strain reactions in medical students preparing for an exam, using days of no work as reference category. Method: The observational design involved students repeatedly self-reporting fatigue, vigor, distress, and the preceding day’s study duration. Hours of nocturnal sleep, attending paid work and compulsory classes, gender, and proximity to the exam were controls in the linear model (generalized estimating equations). Forty-nine students provided 411 self-reports (M = 8.6, SD = 7.0 self-reports/student). Results: Engaging in mentally demanding work was associated with increased distress and work periods > 4 h with increased fatigue. Distress, vigor loss, and fatigue increased in proximity to the exam. Conclusion: Despite students’ high control of their schedule, even short periods of mentally highly demanding work may impair next-day’s well-being when task motivation is high. Freelancers and students might require health-promoting scheduling of work and leisure to avoid an accumulation of strain

Drip water Geochemistry of Niah Great Cave, NW Borneo, Malaysia: a base line study

A base line study was conducted to understand the geochemical variations of drip waters in Niah Great Cave, Sarawak, NW Borneo of Malaysia. Drip waters were collected at three different sites within the cave (D6: SW entrance enroute to painted Cave; D5: centre of the Great Cave, and D8: west mouth Great Cave entrance). The collected samples were analysed for temperature, pH, EC, major elements, non purgeable organic carbon, δ13C and δ18O. Mg/Ca and Sr/Ca ratios, ionic strength, partial pressure of CO2 and saturation indices of carbonate minerals have been used to dictate the geochemical signatures of drip water compositions. The data reveal a wide range of major ion chemistry at three different sites within the cave. The δ13C values in drip waters range from −10.58 to −10.09 ‰. The enriched and the depleted δ13C values are noted at the entrances of the cave due to degassing of water CO2 and warmer air results in lighter fractions of δ13C. The δ18O values range from −6.89 to –6.16 ‰. Minor δ18O deviation in the drip waters are due to the variation in drip rates as faster drip rates show depleted isotopic composition and vice versa. The spatial variability of drip water chemistry results due to water–rock interaction at various conditions of subsurface flow path. This study gives a basis for interpreting the varying controls on drip water chemistry in the cave