The essential oil extracted by hydrodistillation from the flowering twigs of Stevia rebaudiana Bertoni (Asteraceae) was fractioned by chromatography. Forty-three constituents were characterized with the help of GC, GC-MS and other spectroscopic techniques. The essential oil was found to be a complex mixture of mono- and sesqui-terpenes. The cytotoxicity of the essential oil and its fractions was evaluated by sulforhodamine B (SRB) based assay against two cancer cell types viz. C-6 (rat glioma cells) and CHOK1 (Chinese hamster ovary cells). The essential oil and its fractions showed promising cytotoxicity against both cell lines. The highest activity (95.6+/-0.6%) was show by the essential oil on the C-6 cell line at a concentration of 400 microg/mL, which was comparable with that of the standard drug vinblastin. #Stevia#kombucha#ikombucha_ro#ikombucha https://pubmed.ncbi.nlm.nih.gov/25026731/
Stevia, a zero-calorie sugar substitute, is recognized as safe by the Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA). In vitro and in vivo studies showed that stevia has antiglycemic action and antioxidant effects in adipose tissue and the vascular wall, reduces blood pressure levels and hepatic steatosis, stabilizes the atherosclerotic plaque, and ameliorates liver and kidney damage. The metabolism of steviol glycosides is dependent upon gut microbiota, which breaks down glycosides into steviol that can be absorbed by the host. In this review, we elucidated the effects of stevia's consumption on the host's gut microbiota. Due to the lack of randomized clinical trials in humans, we included in vitro using certain microbial strains and in vivo in laboratory animal studies. Results indicated that stevia consumption has a potential benefit on the microbiome's alpha diversity. Alterations in the colonic microenvironment may depend on the amount and frequency of stevia intake, as well as on the simultaneous consumption of other dietary components. The anti-inflammatory properties of stevioside were confirmed in vitro by decreasing TNF-α, IL-1β, IL-6 synthesis and inhibiting of NF-κB transcription factor, and in vivo by inhibiting NF-κB and MAPK in laboratory animals. #Stevia#kombucha#ikombucha_ro#ikombucha https://pubmed.ncbi.nlm.nih.gov/35456796/
Steviol glycosides (SGs) in Stevia (Stevia rebaudiana Bertoni) leaves are important due to their high sweetness and low calorific value. The yield of SGs is dependent on fertilization regimes, but the relationship between nitrogen (N) administration and SGs synthesis is still unclear. In this study, we investigate the effects of N rates on SGs production through hydroponic and plot experiments. The SGs yield was not significantly changed by N fertilization, but leaf SGs concentrations were significantly reduced due to the "dilution effect". Additionally, N addition decreased leaf carbon (C)/N ratio and soluble sugar concentration, accompanied with the inhibited phosphoenolpyruvate carboxylase and L-phenylalanine ammonia_lyase activities. A significant positive correlation between leaf SGs concentrations, C/N ratio and soluble sugar concentration was observed. Overall, we suggest that N-driven Stevia growth negatively affects SGs concentrations. The leaf C/N ratio and soluble sugar changes indicated the occurrence of metabolic reprogramming. #Stevia#kombucha#ikombucha_ro#ikombucha https://pubmed.ncbi.nlm.nih.gov/31195254/
Plant growth and secondary metabolism are commonly regulated by external cues such as light, temperature and water availability. In this study, the influences of low and high temperatures, dehydration, photoperiods, and different growing stages on the changes of steviol glycosides (SGs) contents and transcription levels of fifteen genes involved in SGs biosynthesis of Stevia rebaudiana Bertoni were examined using HPLC and RT-PCR. The observations showed that the transcript levels of all the fifteen genes were maximum under 25 °C treatment, and the transcription of SrDXS, SrDXR, SrMCT, SrCMK, SrMDS, SrHDS, SrHDR, SrIDI, SrGGDPS, SrCPPS1, SrUGT85C2 and SrUGT76G1 were restrained both in low temperature (15 °C) and high temperature (35 °C). Most genes in SGs biosynthesis pathway exhibited down-regulation in dehydration. To elucidate the effect of photoperiods, the plants were treated by different simulated photoperiods (8 L/16 D, 1 0L/14 D, 14 L/10 D and 16 L/8 D), but no significant transcription changes were observed. In the study of growing stages, there were evident changes of SGs contents, and the transcript levels of all the fifteen genes were minimal in fast growing period, and exhibited evident increase both in flower-bud appearing stage and flowering stage. The obtained results strongly suggest that the effect of environmental cues on steviol glycosides contents and transcription of corresponding biosynthetic genes in S. rebaudiana is significant. It is worth to study deeply. #Stevia#kombucha#ikombucha_ro#ikombucha https://pubmed.ncbi.nlm.nih.gov/25500454/
More than 60 naturally occurring steviol glycosides in the Stevia rebaudiana Bertoni plant share a similar molecular structure with an aglycone steviol backbone conjugated with β- and α-glycosidic bonds to different sugar moieties. These glycosides are naturally produced in different quantities within the stevia leaf. Certain minor glycosides with superior sensory attributes, such as Reb D and Reb M, are found less than 0.1% in traditional stevia leaves. New technologies can now produce better tasting steviol glycosides by using enzymatic conversion of stevioside and Reb A, which are abundant in stevia leaf. Several regulatory authorities recently evaluated steviol glycosides produced by enzymatic conversion of stevia leaf extract and approved them safe for human consumption. Steviol glycosides undergo microbial hydrolysis in the colon to generate steviol, which is absorbed and metabolized into steviol glucuronide, and excreted primarily via human's urine. Previous studies have shown the hydrolysis of highly purified individual steviol glycosides extracted from stevia leaf are converted to steviol in the presence of colonic microbiota of adults. Since colonic microbiota of children may be different from adults, this study investigates the metabolic fate in the colonic microbiota of adults and children of the minor steviol glycosides produced by extraction and enzymatic conversion of major steviol glycosides from stevia leaf. Several in vitro incubation tests were conducted in human fecal homogenates collected from adult and pediatric populations with steviol glycoside test samples comprised of a complex stevia leaf extract, a blend of minor glycosides isolated from stevia extract and two mixtures of steviol glycosides produced by enzymatic conversion of Reb A to larger molecules by attaching glucose units via β- or α-glycosidic bonds. Results from these studies clearly demonstrate steviol glycosides produced by extraction from stevia leaf, or enzymatic conversion of stevia leaf extract, share the same metabolic fate in the human gut microbiota from adults and children. Considering a common metabolite structure and a shared metabolic fate in all ages, safety data for individual steviol glycosides can be used to support safety of all steviol glycosides produced by extraction and enzymatic conversion of stevia leaf extract. #Stevia#kombucha#ikombucha_ro#ikombucha https://pubmed.ncbi.nlm.nih.gov/32745585/
Stevia rebaudiana Bertoni is a valuable plant whose products are increasingly used in medicine, pharmacy and the food industry. This necessitates the use of biotechnological approaches for its mass propagation. Establishing optimal conditions for in vitro cultivation is essential for obtaining high biomass and secondary metabolites production. A large number of articles considering the role of plant growth regulators and other additives in the culture medium in the growth and development of Stevia are available in the literature. However, there are no summarized data about the use of nanoparticles in Stevia tissue cultures. Therefore, this review also includes the research conducted so far on the effect of nanoparticles on Stevia micropropagation. Furthermore, the influence of different elicitors on secondary metabolite production and antioxidant activity of in vitro-cultivated Stevia plants have been discussed. By referring to the collected literature, we concluded that biotechnological approaches applied to S. rebaudiana cultivation might improve the agronomic traits of plants and steviol glycosides production. #Stevia#kombucha#ikombucha_ro#ikombucha https://pubmed.ncbi.nlm.nih.gov/36616282/
Recent research dives deep into the impact of autism on marital bonds. Over a 30-year span, parents of children with autism showcased a 36% divorce rate, with specific peak periods. Surprisingly, families of verbally adept autistic teenagers faced unique stressors, leading to higher divorce rates. The strength and resilience of these families remind us of the unique challenges they face.
Hi, I'm not quite sure if this vhdl code and testbench is correct for the given task. Can you take a look?
Design a one-hour kitchen timer. The device should have buttons/switches to start and stop the timer, as well as to set the desired time interval for the alarm. Realize the task using the software package Quartus or in GHDL, confirm the correctness of the project task by simulation.
This is VHDL code:
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
entity Kitchen_Timer is
port (
clk : in std_logic; -- Clock input
reset : in std_logic; -- Reset input
start : in std_logic; -- Start button input
stop : in std_logic; -- Stop button input
alarm : out std_logic -- Alarm output
);
end entity Kitchen_Timer;
-- Declare the architecture for the kitchen timer
architecture Behavioral of Kitchen_Timer is
signal count : integer range 0 to 3600 := 0; -- Counter for timer
signal alarming : std_logic := '0'; -- Signal to indicate alarming interval
signal alarm_en : std_logic := '0'; -- Signal to enable alarming interval
signal alarm_cnt : integer range 0 to 600 := 0; -- Counter for alarming interval
begin
-- Process to control the kitchen timer and alarming interval
process (clk, reset)
begin
if (reset = '1') then
count <= 0;
alarming <= '0';
alarm_en <= '0';
alarm_cnt <= 0;
elsif (rising_edge(clk)) then
if (stop = '1') then
count <= 0;
alarming <= '0';
alarm_en <= '0';
alarm_cnt <= 0;
elsif (start = '1' and count < 3600) then
count <= count + 1;
if (count = 3600) then
count <= 0;
alarming <= '0';
alarm_en <= '0';
alarm_cnt <= 0;
elsif (count > 0) then
alarm_en <= '1';
end if;
end if;
if (alarm_en = '1') then
if (alarm_cnt < 600) then
alarm_cnt <= alarm_cnt + 1;
else
alarm_cnt <= 0;
alarming <= '1';
end if;
end if;
end if;
end process;
-- Assign the alarm output
alarm <= alarming;
end architecture Behavioral; ```
This is Testbench:
```library ieee;
use ieee.std_logic_1164.all;
entity tb_Kitchen_Timer is
end tb_Kitchen_Timer;
architecture tb of tb_Kitchen_Timer is
component Kitchen_Timer
port (clk : in std_logic;
reset : in std_logic;
start : in std_logic;
stop : in std_logic;
alarm : out std_logic);
end component;
signal clk : std_logic;
signal reset : std_logic;
signal start : std_logic;
signal stop : std_logic;
signal alarm : std_logic;
constant TbPeriod : time := 1000 ns; -- EDIT Put right period here
signal TbClock : std_logic := '0';
signal TbSimEnded : std_logic := '0';
begin
dut : Kitchen_Timer
port map (clk => clk,
reset => reset,
start => start,
stop => stop,
alarm => alarm);
-- Clock generation
TbClock <= not TbClock after TbPeriod/2 when TbSimEnded /= '1' else '0';
-- EDIT: Check that clk is really your main clock signal
clk <= TbClock;
stimuli : process
begin
-- EDIT Adapt initialization as needed
start <= '0';
stop <= '0';
-- Reset generation
-- EDIT: Check that reset is really your reset signal
reset <= '1';
wait for 100 ns;
reset <= '0';
wait for 100 ns;
-- EDIT Add stimuli here
wait for 100 * TbPeriod;
-- Stop the clock and hence terminate the simulation
TbSimEnded <= '1';
wait;
end process;
end tb;
-- Configuration block below is required by some simulators. Usually no need to edit.
configuration cfg_tb_Kitchen_Timer of tb_Kitchen_Timer is
for tb
end for;
end cfg_tb_Kitchen_Timer;```
#science
can you send me the code with the modifications so that I know what exactly you mean?
I would rather not, as it isn't a good learning experience for you, and would require some time for me to write the code.
Though if you have any questions about my previous answer, feel free to ask me about it.
As a freebie for you, pay attention to the alarming signal, and the condition that has been set: "The device should have buttons/switches to start and stop the timer, as well as to set the desired time interval for the alarm.". If I wanted the alarm to ring after 50 minutes, how would I do that? And what happens when the timer starts?
From the code I see here, the alarm is going to ring 10 minutes after being started, and it won't stop until an hour passes. And it has no way to set a time for it to ring, it always rings after 10 minutes.
And, not only that, the start signal is never set in the testbench, so the timer is never going to begin.
What do you think about the specifications that the project requires, should I stick to your code or should I add something from my own code?
I would stick to my code, your alarm isn't going to work properly due to its comparisons as I mentioned in my previous comments. But if you want to improve the code I modified, you can change the adjust_interval_up and adjust_interval_down buttons to be synchronized to their own states rather than the clock (make their own process with their signals added to the signal sensitivity list and add an extra asynchronous condition to zero the counter on the original process). If you don't make a change like this your alarm is going to take up to an hour to adjust its timer range.
Does your simulation correspond to a time of 1 hour and should there be alarming on the simulation?
Yes, if you have a 1/60 Hertz clock signal. And you must have alarming on the simulation as it is crucial to show that it works.
